Sonic's System

Hi Sonic

I don't believe there is one setup per room. It would be nice if all recordings had cues that were similar but that is not the case. There are 2 schools here. One finding a happy place for everything, two going all the way with a particular piece of music on a particular recording. I personally like both but enjoy the chase more.

When I heard you describing the sound as an off echo it makes me want to say "think pressure zones". It doesn't matter so much if another pressure zone is ringing if your listen zone is stable. Picture a some what invisible wall between the zones that leek into each other or trying to equalize themselves. In rooms with hard walls it is harder to make the whole room sing in perfect tune as opposed to rooms that vibrate more of a full range response throughout. Adding wood (carefully) to harder rooms is always a good thing.

Hi Michael and Zonees

After Sonic put the small Shutters up and it settled in benefically, I revisited the use of the Musical Fidelity V-DAC in my system. This pocket rocket DAC was tried by Sonic and removed and Zonees will have read my attempts to tune it. But since then I have learnt that I went about it the wrong way, got mixed up and blamed the V-DAC. What did Sonic do wrong?

First, it was placed on a shelf of undefined wood – some sort of chipboard -- supported by 4 MTD lookalikes. These MTD lookalikes don't sound like MTDs. I also removed the PCB of the DAC out of its case to top tune it. The support I used was MW, resitone rods and Harmonic Springs and it was unstable. I could tell because it kept moving about and falling out of tune every couple of days, bolts would slack off, down rods move from where they used to touch, sound varied wildly. An unstable set up is a source of headaches and a moving target. It can defocus a soundstage easily and give odd front to back perspectives.

Then with the PCB out of its case, I could have effectively removed a designed in RFI shield. If so, this means that digital grunge went all over the place and the device became susceptible to RFI from other sources. If that’s not an amateurish piece of Tune, there is also The Cable Torque.

Back then, I also had yet to learn the art of ensuring the most even torque of the interconnects when linking up lightweight gear especially horizontally from shelf to shelf. Sonic has found the best sound when the cable plugs are turned in their sockets gently to give neutral torque so any lightweight gear being connected not tensioned, tipped up or down. The effect is audible and whether it is a case of simple balance and weight distribution or Michael’s tuning trilogy I cannot say but there is an effect.

So this time, Sonic put the V-DAC temporarily on the top of my MGA clamprack. It sits directly on the shelf, no springs or MW yet, and connected to the CD player with MGA T1 cable. The output goes via Bare Essence to the pre-amp.

Initial sound is good. More detailed than the Sony’s onboard DAC, smoother and the music feels more “all of a piece”. Big soundstage and good ambience recovery. It is just Day 1 so Sonic is going to be patient, let it play lots of music and take the next steps one by one. If it works it will probably wind up on Michael’s tuning boards. Just played Rameau’s harpsichord pieces (Sophie Yates/Channel) and Bach’s Violin Sonatas and Partitas (Monica Huggett/Virgin Classics), very promising.

Sonic

"Then with the PCB out of its case, I could have effectively removed a designed in RFI shield. If so, this means that digital grunge went all over the place and the device became susceptible to RFI from other sources."

Could you touch on your findings on this issue a little more?

thanks

Hi Michael

How did the V-DAC fare vs the Sony DVP K380?

When first swapped from the Sony to the V-DAC, the impression is the Musical Fidelity is smoother and sweeter, there being more emphasis on the wood and inner resonances/richness of an instrument. Massed orchestral strings are less strident. The bass is slightly deeper or maybe just in the 50hz to 100 hz range though I think the lowest octave 20hz to 40hz is about the same.

The V-DAC gives images that are slightly better dimensioned particularly in the centre of the soundstage. The V-DAC gives a stronger sense of the acoustic power of instruments like the bass viol and electric bass.

The Sony is upfront, brighter, faster sounding and subjectively more lively. It could also sound angular and rough.

The V-DAC was less compressed and ambience sounded lower in level while the Sony gave more distinct ambient cues. This could be an exaggeration on the part of the Sony. I think it is an accretion because I have rarely heard music in such reverberant surroundings.

The V-DAC could startle more by going louder suddenly with more dynamic punch as some would put it. The V-DAC also let the music flow better while the Sony gave pointed details though when it came to low level details the two were equal.

In the virtual soundstage zone – that is the space between the loudspeakers -- the V-DAC was subjectively ahead of the Sony in solidity.

What happened when I took the V-DAC out of its metal case - in principle exposing it to RFI and allowing all the digital hash the chips generated to get into the rest of my system?

The sound gets thinner and jagged with a subjective feel of increased activity and busyness. Harpsichords became trebly, loud and clattery. After a while, the sound began to be jagged and fatiguing after a short while and the urge to tweak something came in. To Sonic this urge is a bad sign, it means something is out of balance. The best is when I feel “this is good music, I can sit back and listen to the tunes and forget there is any equipment”.

With the Sony, the soundstage wrapped behind the loudspeakers and images were bigger in the middle but smaller at the sides, with the speaker panels becoming more opaque to images.

Sonic tried to tune the V-DAC PCB with resitone rods and a canopy. I guess I didn’t know what I was doing and the whole system became unstable. It was good one day, then bad and when I checked, the top tune rods to be loose. Then I set it right, the music improved only to fall apart after a few days. I also found the spot where the top tune down rod touched the PCB was moving by the day. Also there were MTD look-alikes under the shelf supporting the assembly which could have contributed to the proble and the whole experience was so convoluted that Sonic is hesitant to ever try top tuning the V-DAC board in that sort of canopy/down-rod set up ever again.

In the last two weeks, Sonic has returned to using the V-DAC but is advancing cautiously. No removal of the PCB from the case this time, no top tuning, just letting it settle in sitting on the top of the MGA ClampRack top shelf. So far, the results have been musical and pleasing.

The differences between the Sony and the V-DAC are more noticeable on Day 1 of a switch but with continued listening, the differences narrows by Day 2 or 3. This is not so much a statement of the similarity of sound and quality of the two pieces of equipment but simply that aural memory is short.

Conclusion: the V-DAC is better than the Sony and worth every cent of the price. Noticeably better and certainly far ahead compared to the 7 year old CD player although what it can do in comparison to the V-DAC is impressive.

Sonic

Hi Sonic

Have you thought of making a smaller shield just for the chips? The sound of chassis drive me crazy but fields are no fun either.

Hi Michael

The chips are scattered around the PCB so how do you individually shield them effectively?

As I understand it, the principle of shielding is a Faraday cage approach -- box the interference emitting device or the part to be isolated in a metal casing and electrically ground it so the RFI goes to earth.

Show a pix if you please how to screen just the chips in the way you suggest. Sonic is very curious how something like this can work.

Sonic

This is not the end all be all but sometimes it is all you need. Beyond this you jump the shield to ground then if even that does not work then we build a low mass shield.

Fascinating!

A couple of questions:

a. Why the use of finished Magic Wood -- what happens if unfinished MW is used, and what is the reason for the difference in effect?

b. What is the principle underlying this idea -- normally RFI is shunted to ground thru an electrical or technical earth. In this case, nothing is grounded but there seems to be some sort of absorption, the "copper sponge" idea, no connecting anything to earth. Again what does the copper shielding tape do and where does the wood come in?

c. If two chips say 0.5" x 0.5" square are mounted side by side say 0.25" apart on the PCB, I assume a single MW/copper tape sponge can be used to shield both?

d. If I am using an outboard DAC, should I still shield the processor chips in my CD player? IMO they are still generating RFI into the rest of my system as they are powered. Is this correct?

e. Is this idea just for chips operating at digital signal frequency ranges or do they work for chips used in say the X-30 crossover which are handling audio frequency ranges?

Zonees, if you think these questions to Michael from Sonic are sceptical, they aren't.

The Tune has good scientific underpinnings but involves looking at proven theory from a sightly different angle, which makes all the difference.

Oh yes Michael, one more question:

I have the older Magic Wood with the cherry finish and a few extra end-pieces of from the Cable Grounds that have a grey gun metal finish.

I can use either for the "copper sponge" RFI absorbers -- which work better in this application?

Hi Sonic

a) I find that sometimes the raw Magic wood can make it sound a little dampened. Try it both ways if you want and tell me what you think.

b) RFI is over active electrons that need to settle or look for a place to discharge. Ultimately fields dissipate as they become engaged with other materials. If it's a bigger field than running it to ground is a cool thing, but sometimes you don't need that much shielding to get the job done. In fact too much shielding causes sonic problems of their own. It's all about tuning to the right amount and knowing what RFI is.

c) This should be true unless the one is interfering with the other. Waves and fields can be touchy.

d) Fields, energy and waves are all vibrations. Vibrations are always on the look out to dissipate. All of your parts are giving off fields but the key is to make these fields work together in tune and not against each other. Here's where people get in trouble. They over do it. Any energy's natural form is to transfer till the energy becomes something else. If we force the transfer we dampen and that sound concerns me much more than a little field.

e) As I said above all parts give and take on energy (that's how they move). Shielding is fun to play with but for myself I like to use as few parts as possible and try to spread them apart enough to let them exchange energy while still maintaining their own signature job.

I think it's good to look at all the angles. That's how we learn. For myself the learning never stops.

Yes, use those and tell me which you like better or if we need to run a ground wire.

Hi Michael

That looks like fun. I am looking for the tape now -- a 3M product as I understand it.

If I started this shielding, the V-DAC board must be out of its metal slip case. With no miniplatform, mini clamp rack, or any support for the PCB, can i still get good if the board just sat on the top of my MGA big clamprack with no support? Maybe at most some small MW pieces supporting it at the corners?

Mechanical grounding of a device is so important. There is a big difference in sound.

Sonic

Setting it on the Clamp Rack board is a good place to start listen to it with and without the wood in the corners underneath so you can report on the differences.

Hi Zonees

Sonic has started tuning the system with the V-DAC in the signal chain.

The first step was to take the V-DAC out of its metal case and seat it on the top shelf of my Michael Green Clamprack (no MW wood as spacers). It sounded awful.

What is the nearest analogy to describe what I heard? A lousy old TV tuned wrong with lots of snow in the picture. The music went dead, was bright and felt "whited out". Definition gone, bass extension gone and so on.

Then Sonic cut some cherry finished Magic Wood into squares -- 1.5", 1.25". 1", 0.75". 0.5" and the wood frays or I cut my fingers....I'll get round to it.

Then Sonic went to my nearest Farnell electronics outlet (they call themselves element14 now so they say). Excellent service and knowledge of their product range. They knew exactly what I was asking for and if you wonder what copper tape RFI shileding Michael was recommending, it is 3M 1181 copper foil tape, 19mm. From my phone call to having the copper tape in my car and Sonic on the way was under an hour. Well done Farnell and co!

Sonic stuck the copper tape onto the pieces of MW I cut.

To test the system right, I mounted the V-DAC PCB back in the metal case. Listened and after a few hours the music was back to normal.

I placed the "copper/MW RFI sponges" I made on various parts of the Sony CD player. First -- the CD player's switching power supply, a source of RFI and EMI nasties. Then on the chipsets. Though I am using the the Digital output into a DAC but remember the CD player chips are still powered and active. And therefore a source of RFI -- maybe the interaction between the RFI from the CD player and the V-DAC were making the bleached music.

Very much better. The sound is more detailed and there is no more haze in the background.

Then out came the V-DAC from its casing and the copper/MW pieces on the main processor chip and as many chips as I sit the pieces on.

No more white out. The music is very full, and realistic. A long way from the bleached sound I got with the untreated V-DAC PCB.

Michael knows what he is talking about and the copper tape with the finished MW works great just as he said.

Sonic found that cherry finished MW sounds better than gunmetal gray finished MW in my system. Cherry is lively and musical and believable -- there are people playing music. The gray finished MW sounds closed down, heavy-sounding-coloured and sour.

Another step forward it appears to me.

Sonic

Hi Michael and Zonees

I am amazed how effective the copper tape/MW pieces are. Sonic was looking for spots (i/c chips) to shield and here was one where as my finger came within 1/10 inch of the top of the chip I heard a "buzzzmmmm" through my speakers. No sound when I was away then as I got close to touching it...."buzzzmmmm". How long has this been going on? This must have been messing up my sound.

So powered down the device and placed a 1" x 0.25" x 0.25" finished MW with copper on top. Powered up and reached towards the i/c slowly....and this time silence!

Touched the shield... silence

Where was the chip? In the X-30 volume control section.

The sound of the whole system has gone cleaner with the shields in place. So quiet and new musical details unmasked. Slightly less volume for a given control setting but it really opens up and fills the room and beyond when turned up a step more.

The system with the shielded V-DAC has improved to the point that it is un arguably better than digital-analog conversion using the onboard DAC of the CD player.

Sonic thinks Michael has a product here -- finished MW squares of various sizes with copper tape plus some form of earth drain.

Here is a pix of my V-DAC. See the where the chips are shielded. I am trying out a couple of more spots but doing it carefully because the copper could short something out if I am not careful.









This brings me to an observation: removing top covers, taking circuit boards out of cases may be good for vibrations to bring out the musick but could cause a lot of RFI an EMI problems which why some get mixed results from doing this. RFI and EMI are orrible things and vary with the equipment's environment and proximity to anything and everything near it. The affected gear could be a generator or RFI or affected by RFI or both in different parts of the circuit. So this alone means there is no single solution for the tune application.

Michael, do you agree and want to add something?

Sonic also found that finished MW is better sounding than unfinished MW. The unfinished wood is a bit dead (damped) by comparison and I found cherry to be the nicest sounding finish in my system. The gunmetal grey wood sounds odd...a bit sour and slow.

Also Michael, can you show:

a. How to tune wall warts

b. What more advanced ideas to you have to deal with RFI/EMI

c. With my V-DAC sitting on my clamprack top, how do you suggest I suspend it so as to minimize contact with the clamprack? This is to reduce any interference with the flow of vibrations from the top tuned device below flowing across the shelf.

Sonic

Hi Sonic

These look wonderful! There is so much in tuning to learn and as we get to the point where we realize how much chassis shut down the sound we also need to explore the fields of energy that this hobby entails. Electronic parts radiate. Putting them in a box is the worse thing that we can do to them at the same time learning the art of controlling (tuning) waves is a big frontier that I have been wanting to reveal. Because my designs in this area are patentable I will keep my secrets to a minimum on the forum.

I have designed a Resitone MTD that allows you to put the board directly on the cone surface without worrying about shorting out units. It is made as a solid or as a bell depending on the persons choice.

Wall wart tuning and power supply tuning coming soon. Just have to finish melting a few more. I can understand why they built them the way they did for packaging but they are so over dampened it is nuts.

Hi Michael and Zonees

This week didn’t see that much tuning due Sonic being feeling that the musick from my system was pleasing enough that I didn’t get that urge to go tuning but found some things worth thinking about:

a. The “copper RFI sponges” like all tune devices, there gets to a point where their best work is done and more is not better. I covered every IC of the V-DAC but found the sound was getting a little analytical and dry, so I cut back and the best combo was the number of “sponges” in the last pix I posted, except the IC on the output end of the board which is partially covered in the pix is now fully shielded (see mid LH-end of the board in the pix).

Also the X-30 is down to the one shield that cuts that induced hum. I tried more but the effect was negligible. Less is more. Shields on ICs in the power amps made no effect.

b. Wall warts are over damped. Making wire extensions from the wall wart terminal pins to the mains so they can be set on MW boards are good and Sonic found different supports for the wall warts caused differences in sound. I tried small cones, point up or down, MW bars, small 3/8 x ½” MW pieces with a countersunk brass screw drilled through so a point of 1/8” protrudes with wall wart resting on these point up or having them point down – the most didn’t work only the MW bars (2 per wall wart) were the least coloured.

If nothing else, this shows that wall warts are tuneable. And they better be as more manufacturers are using these little devices to provide the low voltage DC sources to their components. Just like real warts are contagious, wall warts proliferate through audio.

What’s inside a wall wart? Not much. A transformer to turn the 240V AC down to the target voltage – 12v or 18v or 24v – and then a diode bridge to convert AC to DC then a capacitor to smooth the DC out. A transformer and a small PC board inside, that’s all. Simple devices but lopsided in weight, over damped and heat-generating devices.

The polarity of how wall warts are plugged into the AC mains is irrelevant. A diode bridge will always give you the same DC polarity regardless of the AC polarity because reverse DC into a circuit could result in component failure.

c. The introduction of Space Cones is a neat thing. Sonic would like to know more about how to apply them. For instance, I can see how they can rest on things like furniture but how can they be best attached to walls, windows and doors and what is a starting placement?

Space Cones will resonate (heh heh) with people familiar with the Combak and Marigo products and it will be good if we are told more about how they could be used. How big are they?

d. Michael, tell me more about the resitone cones for PCBs. How big are they and how should they be placed under PCBs when there are all sorts of uneven spots and bits of solder and wire sticking out? The V-DAC has lots of solder points and wire stubs protruding under the PCB. I suppose this where the “bell” resitone cones come in. Can post a pix of what the resitone cones look like?

Sonic

Hi Sonic

Sanding Magic Wood today. Will look for that camera. I posted a little more on products.

https://tuneland.forumotion.com/t65-mga-cones-spikes

Hi Michael and Zonees

A new development with Sonic’s system. It has to do with room reverberation time and it started when I was listening to choral music from Palestrina (Naxos), Perotin (ECM) and Vivaldi’s Sonatas a Pisendel Harmonis Mundi). The first two of these recordings are pure vocal pieces and the Vivaldi has pieces with a solo baroque violin accompanied by a harpsichord and a viola da gamba.

While listening to these three recordings, I noticed that the ambience sounded the same – they all sounded like they were recorded in the same reverberant space. But not to be when I checked the sleeve notes – different spaces and the recording of a baroque trio would not usually be done in the same large reverberant space for polyphonal Church music.

Sonic started thinking and reading and came to this conclusion which might be a bit controversial to Tunees. Summary of Idea: My room has a reverb time that is too long and this is giving me a generic ambience and coloring the music I am getting.

Sonic read up my favourite book on acoustics – The Master Handbook of Acoustics (3rd Edition) by F Alton Everest – and learnt a few things that Zonees could find useful:

a. A completely untreated room, 23.3 ft x 16 ft x 10 ft (close to Sonic’s listening room of 21 ft x 14 ft x 10.5 ft) with concrete floor, floors and gypsum board 0.5” on frame construction and ceiling the same has reverb times of:

125 Hz 0.6 sec
500 Hz 2.8 sec
1 KHz 3.4 sec
2 KHz 2 sec
4 KHz 1.8 sec (page 134)

Given a typical room in the Far East where the walls and the ceiling will be made of concrete, the reverb times might be a little longer than even this. Using an online calculator for reverb time, I found a room similar to my listening space will be giving a reverb time in the mid 3 sec and up in the midrange if it were constructed of concrete, brick and tile.

b. The average “Optimum” reverberation times:

Pg 124

Churches (liturgical cathedrals/churches):

10,000 cu ft 1.25 – 2 sec
100,000 cu ft 1.4 – 2.3 sec
1,000,000 cu ft 1.75 – 3.5 sec

Pg 125

Concert Halls (Symphonic music)

10,000 cu ft 1.0 sec – 1.7 sec
100,000 cu ft 1.2 sec – 2 sec
1,000,000 cu ft 1.3 sec – 2.5 sec

Concert Halls (Opera and Chamber music)

10,000 cu ft 0.7 sec – 1 sec
100,000 cu ft 0.8 sec – 1.25 sec
1,000,000 cu ft 1.8 sec – 1.3 sec

This shows that a larger space allows a longer reverb time and for smaller spaces, shorter times apply.

A tiny room with a long reverb gives the effect of a bathroom although the times will decrease in the bass because of the room being unable to support the long bass wavelengths .

But what about the “Optimum” reverb times for a listening room of about 3,000 cu ft which is the size range where Sonic’s room is? From the charts on Pg 125, such a room should have a reverb time of 0.6 sec to 1 sec for opera and chamber music.

Sonic tried the “BOO!” test and in the midrange the reverb time in my room is surely longer than the 0.6 range and ringy too.

This could be where the sameness in ambience is coming from – a long reverb tail. And the reverb tail could mask detail too.

Now a short reverb time should not be confused with an acoustically dead room. It has more to do with enough “burn” in a controlled form that gives an even decay across the audible frequency band.

The mistake audiophiles make is to damp their room with acoustic foam, curtains and carpets which absorb the treble well but these devices are unable to deal with the long wavelengths in the bass. So we get a dull, thick sound that seems to have a perpetual bass overhang going on and the need to turn the volume up to cut through the dullness.

Sonic got TuneStrips and fixed them in the front corners mounted equidistant between the floor and ceiling. Instantly the room went quieter and the “Boo!” gave a distinct sense that the reverb was shortened.

Music played sounded good and the ambience between recordings made in different spaces started to differentiate. I’ll need to experiment further. More coming up.

Michael, your thoughts?

Sonic

A tricky balance. This is one of the reasons I prefer smaller listening rooms with mechanically resonant walls. Although the hand book is incorrect about when we are able to hear bass waves (I've sat in cars doing 20hz) and things of this nature it helps to get us thinking about timing when it comes to bigger rooms. If I had my dream room it would be small and sitting on tall floor joist that ran much bigger than the room.

There are 3 parts to hearing

one, the sound wave length

two, the mechanical vibration of sound

three, the other types of waves in the room

I believe all three of these dictate movement.

To get a true accurate reading of a room you would need to take it one room at a time and one piece of test equipment at a time. For example: lets say we take a room the size of yours and measure it empty, then we take the exact same room and change the direction of the floor joist. The second room would measure completely different from the first. The same is true if we went with and without a dehumidifier, or (with sophisticated equipment) an ionizer. What we hear is in no way what we see on paper after a test. Fun? Maybe, but real? no way.

At TuneVilla Ohio I was able to change sound wave performance at will by going under the room and adjusting the joist. It was an effect that I could only describe as lengthening and shortening the waves. This is when I first turned away from the length theory and went to the length plus mechanics (pressure zone) one. In Nashville the floating tunable rooms taught me much about the mechanics of what was going on in totally different ways. So I guess for me throwing out the handbooks (which seem incomplete) and going off of experience is where I lean toward.

Here's a question for you. Where did you do the boo test? When I came to Singapore the first time. I was interviewed by one of your mags. It was in a gymnasium. He was asking me about waves and such so I gave him a demo (don't know if you can find it or not). He asked me a question about acoustics and how it works in the gym and then the same question at the same place only this time we were surrounded by RoomTune. He was (as well as the other guys there) pretty shocked. When we were inside our little RoomTuned area all the other sound was pretty much gone. Out side of the area it sounded like a gym again. This is a common demo that I have done all over the world with the same results. Basically what I am saying is by you tuning your tunes you are creating your own set of rules and you can find a place where the music all sounds the same or one where each recording has it's own space. Which one you choose will be in your hands but I don't if your long term experience will coincide with the book.

Hi Michael

The view that a small room cannot support long wavelengths and therefore would be unable to allow the reproduction of low bass did not come from F Alton Everest's Handbook. It is a common assertion among audiophiles and I cited it in relation to a smaller room requiring relatively shorter reverb times.

It has been repeatedly shown that small spaces can reproduce low/infra bass frequencies if you pressurise the room and modulate the pressure -- several theories and products have been developed on this understanding such as the well-known infra bass speaker by Graham Holliman from the late 70s and early 80s and the fan subwoofer by Eminent Tech.

To test the reverb decay in my room, Sonic has marked out a number of "test points" round the room and I stand in each spot and clap my hands and shout "BOO!" and listen to the decay. The test points are related to the corners, the 1/4 points, half points, speaker positions, listening seat and rear corners.

Sonic can also employ the assistance of another person to do the clapping etc while I sit in the listening chair.

For sure the sound of my room is a little ringy. But I need to remember that echoes can slide around so a lot of care must be taken when deciding where to site items like DRTs, tunestrips and PZCs.

So far the Tunestrips from Michael are excellent products that reduce the ring and shorten the reverb time without dampening the room.

One other thing that Sonic found is that if a room is too dead or too live, and the tunee uses Michael's products the improvement is strong and clear across all music and speech being listened to as the optimal point is approached. However when we reach the optimal ballpark, we start to find that tuning is required for the best reprtoduction. One CD/LP/broadcast could do with more liveness (tighthen PZC bolts) and the next programme might need more burn (move DRTs/DTs around?loosen PZCs). It is all about increased acoustic sensitivity being increased and using the tune to get to the best setting.

Through the last couple of listening session Sonic has encountered this where I felt a tune on the PZCs or an addition or removal of some MGA device could improve things. I resisted and decided to sit tight. I am after all Sonic Beaver, not Tuning Beaver and I fear the day when I find that every CD and LP I play needs tuning of some form to bloom out. The benefit may be audible and I know this is the way some Tunees get the best sound but Sonic may go crazy.

Oh yes -- the reverb times I listed in my post for churches and concert halls was from me reading the charts/graphs in F A Everest's Handbook. They are accurate IMO to 0.1 of a sec as far as I can accurately read the graphs (they weren't presented as tables in the Hnadbook).

Sonic

Sorry about the handbook mis-quote. I think when I look things up I start reading what people are saying and it is so far away from reality that I just start to roll my eyes and put the writers all in the same box. I do respect math, but it can and is a study that is based on too many absolutes without the practicality of conditions. Listening has taught me that the only absolute is a variable one. On this moving planet at least.

Hi Zonees

As Sonic is letting the system/room with the TuneStrips settle in and me getting accustomed to a listening environment with a shorter decay time, here is an article I found on the development of approaches to studio control room acoustics.

The ideas are conventional and therefore are counter in many places to the Tune but this may be something that helps Tunees broaden their thinking along with their soundstages.

Here is the full article:


50 Years of Control Room Design
by Jan Voetmann

Introduction

Sound control room design is an interesting part of small room acoustics and represents most of the problems from small room acoustics in general: Frequency-balanced reverberation time, proper distribution of room modes, low-frequency reproduction, sound source and receiver positioning, etc.

It should be recalled that the function of the control room is twofold, which is often
overlooked:

On one hand the control room is the “tool” that – together with the monitor loud-speakers or vice versa – should illustrate or auralize the sound engineer’s (and producer’s) efforts in the creative process of the new recording or music production.

This process encompasses putting tracks together, adding sound effects, balancing the mix, creating “space” around the instruments and the vocal, etc.

On the other hand, the control room should also mimic the acoustics of an average living room when checking of the final result of the recording, simply because most musical productions, whether on CD or in broadcasting, are aimed at the listening environment of a living room. For the same reason a number of investigations has been dealing with the acoustics of the living room.

This paper attempts to give an overview of sound control room design over the last 50 years, from the control rooms in broadcast and recording industry in the 1950’s up to today’s standard listening rooms aimed at detecting differences in modern bit reduction systems. Different and sometimes quite controversial “schools” popped up during the period and will be described. Basic acoustical design considerations of these schools will be discussed and examples of characteristic designs shown.

The paper will concentrate on the room acoustical aspects of the control room. Neither sound insulation, nor HVAC, nor control room equipment (except a little about loudspeakers) will be discussed.

A note on the reverberation time should be mentioned here. Some acousticians claim that the term reverberation time should be or already is earmarked to the situation where a stationary, diffused sound field is built up and after seconds interrupted. The decay time of the first 60 dB after the interruption is by definition the reverberation time. A stationary, diffused sound field is not being built up in a control room because of the heavy sound absorption, so it is not possible to talk about reverberation time in this situation.

Listening to a bass drum kick in two different control rooms with and without adequate
absorption of low frequencies gives you two very different perceptions. So what are you listening to, reverberation time or decay time?

From the author’s point of view the best measure of the perception of the impulse response of the room is the reverberation time (or maybe: the early decay time). But it is also crucial to look at the normal modes of the room, and realize that the decay of the sound is the decay of the eigentones of the room (or the room modes). All other tones not being eigentones will disappear immediately when the sound source is interrupted. So having this in mind, the term reverberation time will be used here as one of the important metrics to characterize the room.

Control room design in the 1950’s

It is characteristic that most of the development of control room acoustics took place in the USA, and that the interest in building better control rooms began in recording studios for pop music at the time of the introduction of stereo recordings in the mid-fifties. From pictures of that time the control room was a small acoustically untreated or randomly treated room, typically placed in the corner of the studio or as an excrescence on the studio box.

The author did not find anything about the acoustical conditions of these early control rooms, only vague descriptions of the acoustics of the studio, and without measurements. But it should be remembered that in those times acoustical measuring equipment was rare, heavy, not portable, expensive and mainly belonged to acoustic laboratories. So, for many reasons this kind of equipment was common to the studios, and therefore very little documentation exists.

A small number of great, dedicated designers showed up at the time, and around the recording sessions they were doing nearly everything by themselves. They spent all their time and efforts in order to get the recordings sound as fine as possible, inventing new gear, building their own mixing consoles as well as reverberation chambers and microphone preamplifiers, creating new sounds effects, etc.

They based their judgment mainly on what their ears told them. Documentation in the shape of acoustical measurements was not backing their judgments, or at least it has not been possible to find such documentation.

Sound absorbent materials had been documented through laboratory measurements for many years, and those measurements were used as basis for the design of at least the studios. Most of the absorbers of the time were either perforated plates of wood with mineral wool behind, or fiberboards with holes drilled into the board (“Cellotex”). These absorbers were typically mid-frequency and high-frequency absorbers, and the documentation rarely went below 125 Hz. So, the room behavior regarding low-frequency reverberation time was more or less disregarded and beyond control.

At that time stereo was becoming the new recording technique, and it started a genuine interest in design of a new type of control room. Symmetry along the median plane through the room became an important issue in order to keep the stereo picture stable, and many of the old control rooms could not be redesigned because of this. It was time for interesting experiments such as the horn-coupled control room designed by Bill Putnam, and also Mike Rettinger was active as a designer and also an author of a number papers and books about studio and control room acoustics.

A New Generation of Control Rooms

At this time a new generation of control rooms popped up, mainly because of the attention on stereo reproduction. One of the important designers was Tom Hidley, engaged in building new studios early in the 1960’s for major American recording companies and with a keen eye to the acoustics of the control room. He has published very little about his design ideas, but in a rare interview he relates to the time, when he was working as a sound engineer in Hollywood. The company staff often went to the flat roof of the building to spend the leisure time between recording sessions. They installed a set of well-known professional monitor loudspeakers on the roof, so they could relax and listen to music. In the interview Hidley explains that these loudspeakers, playing in an open hemisphere, to him was the best sounding loudspeakers he had heard, and he wanted this impression to be found in the control
room.

In this statement we have a description of an interesting acoustic situation. The loudspeakers are emitting sound in an almost perfect 2π-space with the roof floor as the only reflecting surface. And with no reverberation at all. When this situation is trans-formed to a real room, we are looking at a semi-anechoic room which is not desirable for several reasons. One reason is, that it is practically impossible to realize within the size normally reserved for a control room. Another reason is the earlier mentioned second purpose of the control room, namely to act as a kind of living room enabling you to evaluate how the final production will sound in a “real” room. The sound perception of the semi-anechoic room is simply too far from our daily experience.

Hidley’s interpretation of the sound perception on the roof was realized in a series of control rooms, with the following common features:

• Absolute symmetry along a median plane in the room to create a stable stereo
image

• No reflections coming from the back wall

• No reflections coming from the ceiling

• Monitor loudspeakers built into and flush mount with the front wall of the room

• A short reverberation time of the control room down to and including low frequencies (the 63 Hz-octave band)

The latter was already mentioned by designers such as Bill Putnam and Mike Rettinger, and this might be the most important single acoustic parameter of the control room.

For unclear reasons early reflections along with the direct sound from the monitor
loudspeakers in the front of the room were accepted and recommended by Tom Hidley.

One very practical reason is of course the window to the studio, as it is widely preferred to have visual contact between the artists in the studio and the sound engineer and producer in the control room. No specific explanation of this substantial deviation from “the acoustics on the roof” situation has been found. Some descriptions are discussing the importance of diffuse early reflections from the front end of the control room, but not why. Exactly this point was later heavily discussed by a group of other control room designers.

In his early designs Hidley introduced a reflecting canopy above the mixing console. The reason for this never became clear either, and the canopy was removed in later designs. In order to obtain as much sound absorption in as broad a frequency range as possible Hidley created his famous “bass traps” consisting of elements of mineral wool hanging vertically side by side at a height of maybe 2-3 meters. The effect can be compared with the effect of the mineral wool wedges of an anechoic chamber. The wedges create an impedance matching between the air and the rigid boundaries of the room, so there will be no (or very little) reflection from the boundaries back to the room. Because the length of the bass trap (or of the wedge) along the direction of the sound the effect can be extended to rather low frequencies, e.g. 50 Hz.

A peculiar detail is the name “bass trap” as the absorber is not especially effective at low frequencies; it is in fact a broadband absorber, just like the sound wedge. The bass traps were never documented by laboratory measurements, maybe because of the difficulties of doing laboratory measurements at such low frequencies. An attempt to measure the bass traps was done in Denmark in the late 1970’ies by means of a large plane wave tube of concrete in the basement under the Danish Broadcasting Corporation in Copenhagen.

In 1982 Hidley was commissioned by the same Danish Broadcasting Corporation to design a new control room for the concert hall, called Studio 1. The concert hall was inaugurated in 1946, and the original control room was very small and unsymmetrical, typical of that time.

Another larger space for the new control room was found, but without direct vision to the concert hall. Hidley’s ideas were modified by the house architects in order to make the room fit into the overall interior design of the (protected) building.

All the characteristics of a Hidley control room can be found here. The front wall with room for built-in monitor loudspeakers (they were later replaced by free-standing monitors, and the remaining holes in the front wall were filled with sound-absorbing material). The front part of the side walls includes both glass elements (daylight) and a stone wall giving diffuse reflections (!), and a cupboard on the opposite side wall was covered with a glass door in order to obtain symmetry. Bass traps have been installed above the ceiling to a height of approx. 2.5 meters, thus obtaining effective absorption down to low frequencies. This is also the case in the rear part of the room, where curtains are hiding bass traps as well.

The control room has a very flat reverberation time as a function of frequency, and the room was very favourably reviewed by the sound engineer’s right from the beginning. Most of the productions are classical music.

Later Hidley got another contract from Danish Broadcasting to design a new studio with variable acoustics for “modern” multitrack pop music productions. In this case two of the original old studios were reconstructed and combined into one, and a new control room of thelatest design was included. The studio complex was inaugurated in 1984.

In this control room we find again some Hidley characteristics: The built-in loudspeakers in the front wall, the (hidden) bass traps in the ceiling and in the rear part of the room. But some modifications have been introduced. The original reflective front wall and front part of the side walls are now to some extent absorptive. And part of the rear of the side walls are now made reflective, rendering sound reflections back to the sound engineer in a diagonally fashion, meaning that reflections from the left monitor will hit back from the right, rear part of the room.

Why was that?

To try to understand this we must go back a number of years to around 1978.
At that time Hidley and his company Westlake Audio had built a series of highly successful studio complexes for major clients, both independent studios and large recording companies. But triggered by a new and revolutionary measuring technique called Time Delay Spectrometry, a completely new control room design appeared, and everything was changed once more.

TDS, Time Delay Spectrometry

In order to quantify the “sound quality” of the control room the so-called “house curve” is often used. By this a pink noise signal is fed to the monitor loudspeakers (one at a time) and picked up by an omni directional microphone at the listener’s position. The microphone signal is processed through a 1/3-octave spectrum analyzer, and the resulting curve showing the sound level as a function of frequency is the “house curve”.

Ideally this curve should be flat up to 1-2 kHz with a slight roll-off towards higher frequencies. The actual “house curve” is influenced not only by the loudspeakers, but also by the position of the loudspeakers and the microphone because of the modes (the eigentones) of the room. This is the background for introducing (sometimes substantial) equalizing of the signal fed to the loudspeakers. This procedure is sometimes misleading called “room equalizing”. To minimize the need for equalizing loudspeakers flush mounted with the front wall are often preferred, although with obvious practical disadvantages.

The use of the house curve introduces a serious problem because the use of a steady-state signal, which means that time-varying details cannot be detected, and the direct sound from the loudspeakers cannot be separated from the early reflections.

In contrast to this Time Delay Spectrometry is based on a time-varying signal, a sinusoidal sweep, fed to the loudspeakers. The signal is picked up by the microphone and analyzed by means of a narrow-band filter, which tracks the sinusoidal sweep in such a way that the filter is “open” exactly when the instantaneous tone in the sweep arrives at the microphone.

Depending of the time delay between the instantaneous frequency of the sweep and the centre frequency of the narrow-band filter, different parts of the combined signal of direct sound plus reflections can now be separated and shown graphically.

This new measuring technique was invented by Richard Heyser in the late 1960’s for other purposes, but now it was used by Don Davis and Chips Davis among others to analyze the house curve in different control rooms. And in control rooms with hard, sound-reflecting front walls as in Hidley’s design, they could show that early reflections created “bumps” in the house curve leading to a less-than-optimum situation for the mixing engineer. In other words acoustical comb filtering was the result.

The Live-End-Dead-End Control Room

Around 1979 Chips and Don Davis introduced a completely new design concept and named it LEDE, Live End Dead End. The idea was, contrary to common practice at that time, to make the front end of the control room as non-reflective as possible, thus enabling the mixing engineer to hear only the sound from the loudspeakers. Because an anechoic control room is not desirable, reflections had to be reintroduced in some way. These reflections should not be specular, they argued; otherwise one would end up with the same disadvantages (comb filtering) as with reflecting front walls. Necessary reflections should come from the rear part of the room and be diffuse.

There are several ways of obtaining diffuse reflections, but an idea introduced by M.R.
Schroeder in 1975 and originally intended for concert halls appeared to be very useful for the new control rooms.

Another aspect of the LEDE principle was the request for a minimum size of the room,
especially a minimum depth of the control room. This caused sufficient delay of the arrival time of the early reflections at the mixing engineer’s position was the explanation given.

Also in this design the overall request for room symmetry along a median plane as well as a controlled reverberation time down to low frequencies was emphasized. The live-end-dead end principle quickly became successful among designers and engineers, and a lot of control rooms were made based on the principle.

The psychoacoustic theories behind the live-end-dead-end design have been much debated, especially the interpretation of the Haas effect into how you in the control room can hear the sound being recorded in the studio. The Haas effect was originally a result of research of the audibility of a single echo, with two loudspeakers in front of the listener, one loudspeaker radiating a speech signal and a second loudspeaker radiating a delayed version of the same sound. The experiment was a mono signal experiment, and the relevance to the live-end-dead end design was not clear.

In some papers it was recommended to let reflections come back diagonally from the rear of the room, and maybe Hidley (see above) got his ideas for Control Room 3 of Danish Broadcasting from there. Anyhow, from the pictures it is obvious that some-thing has changed drastically compared to his original design.

The “Reflection Free Zone” Principle

In continuation of the live-end-dead-end principle – or maybe as an extension – the
“reflection free zone” concept was introduced by another group of designers (and
manufacturers of diffusors) around 1984 as a logical step further. Based on a purely
geometrical basis, the idea was to form the front part of the walls and the ceiling, in a way that all reflections were passing round the mixing area, thus letting the direct sound of the loudspeakers radiate unaffected. The approach is only valid for rather high frequencies, but as the goal was to maintain a stable stereo image, which is related to a frequency range from approximately 500 to 5000 Hz, the idea seems to be justified.

Interesting enough, thinking back, a large number of international top hits of that time were produced in studios and control rooms designed by Hidley, and suddenly a new control room design based on more or less complete opposite ideas was the only appropriate way. Thesituation was more or less triggered by the new TDS measuring technique, though interesting enough this was not connected to human sound perception. To the author’s knowledge no listening tests were made, except of the type where the designer and his client walk into the new control room making their judgment regarding the sound quality.

Documentation was typically made by means of a measuring technique able to reveal
variations in the spectrum, which may or may not be perceived by the listener. As one critic puts it, the actual measuring situation corresponded to “a listener with one ear without thepinna, deaf on the other ear, and lying on one side!”

The real situation is, of course, a little bit different, nameley: a listener with two ears wit pinnae on either side of the head, and with a head and a body. A dummy head measuring system would come much closer to the real listening situation, but proper analysis methods and more psycho-acoustic understanding is needed.

The Control Image Design

Up to about 1990 most of the development of acoustic design of studios and control rooms took place in the USA. It was driven by and large by the big recording companies, in Hollywood and New York. In Europe the development took place mainly at the national broadcast corporations, which at that time had fine research laboratories and expertise.

Yet, there seems to be no original contribution to control room design within Europe until Bob Walker from the BBC came up with a new control room design around 1992-1993. His idea was to get a zone around the sound engineer without disturbing early reflections, more orless like the Reflection Free Zone design mentioned above, but without introducing huge amounts of sound absorbent material and the consequently very short reverberation time. Bob Walker’s design goal was a reverberation time closer to the living room standard, 0.3 to 0.4 seconds, and early reflections entering the listening zone should be down 15-20 dB within a time window of 20 msec.

The approach was purely geometrical, introducing a circle around the mixing position,
placing the two monitor loudspeakers in front of that position and preventing any reflected sound rays from entering this circle. What shape of the adjacent surfaces could then be expected?

By means of a CAD computer program it became possible to draw up these surfaces, and some interesting new shapes appeared. They were modified into realistically shaped side walls, front wall and ceiling, and a test room was built at the BBC based on these principles.

Free-standing loudspeakers are standard in BBC control rooms, so the design was meant to work in this case, where most of the design principles described above required or recommended loudspeakers to be built into the front wall.

To prevent this new design concept from being mixed up with the Reflection Free Zone
principle it was named Controlled Image Design, CID. A number of control rooms based on this design were built by the BBC, and measurements done with a MLSSA-system. MLSSA (pronounced “Melissa”) is a measuring system with more or less same attributes as Time Delay Spectrometry, but using controlled impulse trains in order to enhance the signal/noise ratio of the measuring situation. MLSSA documented the concept of CID and showed that the design goals were essentially met.

To the author’s knowledge this design has not been implemented outside the BBC, although it contained some interesting viewpoints, especially by not requiring huge amounts of absorption material, which takes up a lot of space (and rent!). Maybe more important:

Controlled Image Design room renders an acoustical perception closer to a real living room as opposite to control rooms with their very uneven absorption distribution and extremely low reverberation time.

The Non-Environment Control Room

During all the years where design of control rooms has been discussed, it has always been raised as a problem, no matter what design philosophy you preferred, that the sound of the recording/production changed more or less, when you moved from one control room toanother (also within the same design concept). This, of course, leads to speculations of a design of a neutral space, letting you listen to the pure sound from the monitor loudspeakers without sonic influence from the room itself.

A recording situation being more and more international, meaning that the tape, the hard disc or the bit stream of the recording being passed from one studio to the next, adding tracks, effects etc. renders an increasing demand for preserving the sound of the recording during this process.

In order to make a final solution to the problem, Tom Hidley together with Philip Newell came up with a quite controversial proposal around 1991, where anything left of real room acoustics was set aside for the goal of having an absolutely neutral acoustical environment, the non-environment.

Despite earlier research pointing out that sound engineers preferred a “real” room (yet with a short reverberation time) contrary to an anechoic room, the non-environment proposed semianechoic conditions, where the only room surfaces left were the front wall and the floor, acoustically speaking. The remaining walls and the ceiling were made (nearly) totally sound absorbent. Hidley re-introduced the “bass traps” (still “broadband absorbers”), and they will work down to around 40 Hz with enough space available. It has been claimed that they can be effective down to 20 Hz, but documentation of this has never been published. The bass traps
are installed in the ceiling, in the side walls and in the back wall.

Not much documentation of the rooms has been presented so far, but the reverberation time must be non-existing. A number of the rooms have been built in England and Portugal by the original designers, and the sound of the rooms is being enthusiastically described, but the fact is that very few have been built; maybe because of the complicated and very costly design.

The author is in line with the non-environment designers that the “absence” of acoustics in this type of room will probably preserve the sonic characteristics of the recordings much better, when taking them from one non-environment to the other.

Standard Listening RoomsIt seems that no real improvement or new design ideas in control room design have been introduced since the beginning of the nineties. Most of the development of small room acoustics has been focused on “well-behaved” listening rooms for studying loudspeaker configurations in multi-channel environments such as “home theatre” or 5.1 loudspeaker setups.

Another important application of controlled listening environments has been in the
development of bit-reduction algorithms. In this case very small sonic differences – called transparency – between the bit-reduced signal and the original signal have been studied.From intense collaboration between industry and broadcasting a new standard for listening rooms was introduced, partly based on earlier work and standards for listening rooms in broadcast corporations and cooperating research institutions.

The final result is the EBU Tech. 3276, “Listening conditions for the assessment of sound programme material: monophonic and two-channel stereophonic” from 1997. This standard includes detailed requirements for a listening space for this type of research. All parameters discussed above are quantified in this standard: room dimensions and ratios, tolerance limits for reverberation time as well as room response, time window and level of early reflections, and background noise limits.

The basic shape of this listening room is the box shape.

The EBU Tech. 3276 standard is the basis also for rooms for controlled listening tests with test panels for quality assessment of reproduced sound (e.g. loudspeakers) or for product sound quality (e.g. household machines). Experience in using this standard as design criterion for new control rooms is sparse.

Summing Up

Looking at control room design during all these years it seems to have been quite easy to introduce controversial ideas in the field, and also to get these ideas accepted as long as some overall principles are maintained. One overall principle is to keep strong symmetry, which is related to the balance of multi-channel recordings, another principle is to have a controlled, short reverberation time down to low frequencies. The importance of early side wall reflections has yet to be discussed.

Over the years a small number of “schools” with quite different backgrounds seem to have dominated the main road of control room design. Besides these trends a large number of “individual” designs have been carried out.

There seems to be only limited documentation of the acoustic properties of the rooms, and most of the design has been based on assumptions or theories from quite distant and different fields, where the positive effect for the actual application has not been verified. Many of the designers were autodidact with limited theoretical knowledge within fields as e.g. room acoustics or psychoacoustics, and intuition has been a driving force. This need not be a limitation for designing good rooms, and many examples show that.

Documentation of the listening experience in different control rooms by means of a test panel could be very elucidating in order to select facts from myth. One way could be to record appropriate program material with a dummy head in a number of control rooms of interest and subjectively rank them according to preference by a listening panel. Recent experiments on transforming a listening experience to a remote listening panel by means of a dummy head have shown very encouraging. This has been the case e.g. in HiFi car audio design.

Also the developing of measuring systems based on dummy head recordings together with a proper two-channel analyses based on recent research results within subjective listening experience and room acoustical attributes might be the future for documenting the sound quality control rooms (and other acoustic rooms).

Conclusive (sic?) Remarks

It has been the purpose of this paper to present different acoustical design ideas for control rooms during 50 years, in which period almost all major development in recording techniques has taken place. The author has been through a number of papers in order to make this overview as complete as possible and must be excused for any omissions or overlook.

It is hoped that this presentation would inspire fellow colleagues to dive into the field and come up with better explanations or ideas in order to quantify the overall sound quality factors in these small, but demanding spaces.

It has been interesting to collect and select the information presented here. Any correction, elucidation, or new information will be received with gratitude by the author.

References

Jim Cogan and William Clark
Temples of Sound, Inside the Great Recording Studios
Chronicle Books, San Francisco, 2003

Milton T. Putnam
A Thirty-Five Year History and Evolution of the Recording Studio
Pre-print no. 1661, AES 66th Convention, 1980

Milton T. Putnam
The Loudspeaker and Control Room as a Wholly Integrated System
JAES vol. 31, no. 4, April 1983

Michael Rettinger
On the Acoustics of Control Rooms
Pre-print no. 1261, AES 57th Convention, 1977

Michael Rettinger
Acoustic Considerations in the Design of Recording Studios
Pre-print no. 1261, AES 12th Annual Meeting, 1960

Don Davis, Chips Davis
The LEDE™ Concept for the Control of Acoustic and Psychoacoustic Parameters in
Recording Control Rooms
JAES vol.28, no. 9, September 1980

Neal Muncy
Applying the Reflection Free Zone RFZ™ Concept in Control Room Design
db, July-August 1986

Jack Wrightson
Psychoacoustic Considerations in the Design of Studio Control Rooms
JAES vol. 34, no. 10, October 1986

Jack Wrightson and Russ Berger
Influence of Rear-Wall Reflection Patterns in Live-End-Dead-End-Type Recording Studio
and Control Rooms
JAES vol. 34, no. 10, October 1986

Peter D’Antonio and John H. Konnert
The RFZ/RPG Approach to Control Room Monitoring
Pre-print no. 2157, AES 76th Convention, 1984
D. Popescu
A Studio with Variable Acoustics for Multitrack Recordings
Pre-print no. 2075, AES 75th Convention, 1984

R. Walker
A New Approach to the Design of Control Room Acoustics for Stereophony
Pre-print no. 3543, AES 94th Convention, 1993

Philip R. Newell and Keith R. Holland
A Proposal for a More Perceptually Uniform Control Room for Stereophonic Music
Recording Studio
Pre-print no. 4580, AES 103rd Convention, 1997
EBU Tech. 3276
Listening conditions for the assessment of sound programme material: monophonic and twochannel stereophonic
European Broadcasting Union, Geneva, Switzerland, 2nd edition, May 1998

Hi Sonic

Reminds me of Studio B in the RoomTune Factory. Studio B was my time field studio where I tested time, space and material reaction. It was set up as a 12" on center grid and went from full anechoic to full live. The grid could be setup to have only a narrow direct path from the speakers to the ears and all the way to open to the wall. Pretty interesting!

Hi Michael

Sonic cannot tell from your description what Studio B was about but from the paper I posted it appears there is a lot of mental theory but not much listening behind those control room designs.

By listening, I don't mean studio engineers recording things and mixing down stuff. From my exposure to studio sound, you may be surprised that there is a lot of work but little critical musical listening going on. I have had the time to sit in a studio and listen to familar CDs and hearing the music is a different experience compared to recording a voice reading a text, hearing distortion or noises and so on. Recording work and music listening are very different.

Also our ears are adaptable, actually very adaptable. The decay time in my room has shortened a lot and over time I find Sonic is getting accustomed to the shorter decay times even though when on first listen, things could be strange.

The other thing I get from the paper is that "professional" control rooms can have wildly differing decay times in the room (between the front, sides, and rear walls). Sonic feels there is something wrong in this -- the real world musical spaces do not present us with seriously differing decay/time effects from wall to wall, point to point. Things transit smoothly, the sudden changes in studios may be the work of theoreticians who plan, build but may not listen to music and speech with one eye (ear?) on what the real thing sounds like.

And among audiophiles, there is this attachment to the word "professional", and the belief it confers something more wonderful to the music.

"Professional" is merely a set of parameters, not a guarantee of musicality. "Professional" could mean -- the speaker/amp can be thrown into the outboard studio van and still work...the balanced outputs can connect two pieces of gear 100 feet apart with no hum and intereference from mobile phone and meet certain frequency response specs never mind that a single ended, unbalanced system may sound better thru lower parts count up to 20 feet cable runs, beyond which RF noise and hum and other losses become a problem.

Domestic and Professional and Studio just mean different design objectives and trade offs. The question is "how does the music and the sense of the recording space sound?"

Sonic

Hi Michael and Zonees

Sonic’s attempt to shorten the reverberation time of my room and getting it more even seems to have concluded successfully.

What I used to get things working – balancing between a controlled “BOO!” and “Handclap!” and acoustic dryness -- were two Tunestrips at mid-height of the front corners, EchoTunes in the four lower tri-corners of the room and the two presently used Echotunes on the mid-top of the front wall and the mid-top of the side wall remounted.

By remounting the ETs, I mean Sonic placed them across the corner like a Tunestrip rather than mounting them flat on the vertical wall as before (and recommended in early RoomTune literature). I noticed Michael did this for Bill333’s wonder-room and in my room it made a big difference to solidify the soundstage and give inner depth to the sound of instruments.

Transients are sharper and had more snap. Michael do you recommend that this becomes the standard way of mounting EchoTunes? Mounted flat on the wall, their effect is positive but subtle. 45 degrees across the wall/ceiling joint, they make a more audible difference.

With the shortened decay time, the music has become tighter and more in-the-room. The “Boo!” test shows a decay that is controlled with an absence if ring. The amount of ambience being noticed is lower, possibly showing this was not in the recordings but a room-induced effect from the acoustic being over-live/reverb time too long. But what ambience there is audible is varies from disc to disc and is in the right context of the recording with the venue it the performance should be in.

This seems to be a comfortable point. From what I read, some “professional” applications have a reverb time of as low as 0.15 secs (a comfortable range is supposed to be 0.3 to 0.4 secs) also Zonees who have read the long article I posted on control rooms will have seen that some “professional” set ups have very uneven acoustic characteristics. While I am in no way qualified to criticize Hidley et al, it appears to Sonic that the BBC approach to control room reverb plus what their target sounds appear to be from my listening to music through the various generations of BBC studio monitors seems to point to a better balanced and sane path.

About my V-DAC

Michael, you recommended me using your resitone bell cones (that is a cone hollowed out) to support my V-DAC PCB. The PCB is 6 inches long and 3.5 inches wide. How many resitone bell cones do you think I should use given the small size – 3 or 4?

Sonic