Acoustic Education:

Live-end/dead-end control rooms
"The control room or listening area has a different acoustic purpose than the recording studio, resulting in a slightly different set of acoustic parameters to control. Generally, the listenr only wants to hear the direct sound coming form the monitor speakers, with no influence or coloration by the room's acoustics.
To prevent stray reflections, the wall areas behind and directly adjacent to the speakers are normally treated with sound absorbing materials such as acoustical foam or wall panels to provide a "dead" end to the room. The opposite or back wall is left live and can be treated with diffusers to break up any possibility of standing waves within the room. This will create a small early time gap between the arrival of the direct sound from the live end. This technique is known as "live end/dead end" acoustics" and has been the standard in professional listening environments for many years.
This design will create a very clean recording environment with better sound clarity,improved stereo imaging and smoother frequency response."
Acoustical Solutions-www.acousticalsolutions.com
Thus my method stated above has no name but has worked for my dipoles for may years.

gregadd November 23, 2004 20:40

Gregadd: "Live end, dead end" or "LEDE" design, as it applies to a listening space for a playback system (as opposed to a concert hall), conventionally means absorptive treatment at the speaker end, and diffusive (as opposed to reflective) treatment (or no special treatment at all) at the listener end.

zaikesman November 23, 2004 18:32

There was never any intent to suggest it was a mistake. Being someone who tried to put relatively large speakers in medium to small size rooms, room placement was always critical. I never found that to be as critical in large rooms. At your level we are talking about extracting the last bit of performance out of every component.
I generally tuned my speakers off the back wall. Starting with the rule of thirds and moving them back to the wall until the image collapsed. Them moving them out to a point where they maintaned thier slam but imaged properly. In short , too close to the back wall- no imaging. Too far out-no slam. Then I would adjust the horizontal separation and seating position until a solo voice voice appeared to come directly fromm a source directly in the middle and and 1'-2' behind the speakers. Obviously I was a fan of small scale jazz. Orchestral music and big band jazz imaged quite well.

As Raul would put it, I am "inexpert" on this subject. Trust your ears.

gregadd November 22, 2004 13:21

Yes the Dali is a dipole, at least the ribbon is. The woofers are ported and the design and driver size reminds me of the Dynaudio Evidence Temptation, a speaker I very much respect.

My Soundlab was a single driver dipole and responded very positively to the acoustical treatment. Nothing about that treatment has changed since my acquisition of the Dali's,

With Soundlabs my soundstage and depth extended out of my living room into my neighbors back yard, The sense of time decay was flawless and tonal balance was perfect.

Hard for me to believe the treatment was in any way a mistake.

albertporter November 22, 2004 04:49

Is the dali a dipole?I think you know where I'm going. I try to follow the rule of thirds. Speakers one third of the way into the room. We'll kick this around some more when the dalis are dialed in.

gregadd November 22, 2004 02:52

So it was an intentional decision to go symmetrical. It's been a while. I was taught the ideal room shape would be a trapezoid ( no sides parralell)

More like an intentional decision to retain the existing symmetrical dimensions due to cost. It would be nice to begin with a clean slate but not possible in my case.

Already mentioned in this thread, the ceiling has a cavity (not visible in the photos except where a worker is) and this space along with the walls are all treated with multiple layer of wood, sheetrock and acoustical treatment. The cloth is also acoustical but primarily it is there to HIDE the treatment.

The space behind the Dali's is 4.5 feet to the rear wall and 5.6 feet from the corner. Consider too, the "wall" is solid RPG diffusion panels over twin layers of 5/8 solid core plywood and the cavity is filled with acoustic batting.

I suspect the speakers "see" more space than physically exists. At least that is my understanding of the concept. Perhaps Rives or another expert can comment?

For what it's worth, the formula on George Cardas web site about placement of speakers based on room dimensions as well as experiments over a 15 year period with Soundlabs arrived at placement of the Dali's of within two inches of the same spot. I am open to experiment but doubt there is much point until all is settled in.

albertporter November 22, 2004 01:14

So it was an intentional decision to go symetrical. It's been a while. I was taught the ideal room shape would be a trapezoid ( no sides parralell). The ceiling would start at one height at the speaker end and get taller at the other end. Idealy the ceiling would have what looked like steps leading to the non speaker end of the room. The floor would be concrete covered some absorbent material.
Thus you would have an ambience but no canellation effect or standing waves.
I also remember the discussion of the live end dead end room. Reflective surface behind the speaker and dead end behind the listener. Of course damping would be put at the first point of reflection at the side walls.
With the advent of tube traps I have seen a room within a room created( especially at hi fi shows). The sheer size of your room would free you up from some of these problems. I notice your speakers appear to be close to the real wall and the corners.
PS. thanks for advice on speakers. Maybe I'll get down to Texas to hear them.

gregadd November 22, 2004 00:47

According to the acoustics designer, reflections can be controlled by either asymmetrical dimensions and / or damping.

To completely restructure the framing of my home (built in 1956) would require tearing down the wall between living space and the kitchen or living space and my photo studio. Both of these are load bearing walls.

This remodeling was partially paid for by my insurance company when a water leak destroyed most of my foundation. The process to remove all the defective timbers also required removal of my air conditioning duct work, stringer beams, some of the wall support studs and in some areas, all of the sheetrock. The biggest expense was tearing out solid Oak hardwood floors and about 650 square feet of Terrazzo stone.

I took the opportunity to put in my own funds and upgrade this repair to the status displayed here. As mentioned before, Russ Berger Design Group helped with acoustics for free because we have been friends for years, otherwise I could not have afforded him.

Russ's last detailed drawing for a similar high end room (being built here in Dallas) was $36,000.00. The plans were sufficiently detailed that bids are coming in at about $340.00 a square foot.

Applying these figures to my space, this project would have cost about $221,000.00. That is WAY beyond my means, so I am grateful to have achieved what I did with less budget.

I will say the Soundlab speakers were sounding as perfect as any system I have ever heard. No doubt the new cores helped but if this room was not great, the sound would not be great.

For now, I must continue to break in my Dali speakers. They are showing promise sonically and I am completely satisfied with their construction and the support I have received from the importer and the designer in Denmark.

albertporter November 21, 2004 23:57

I keep looking at your room renovations. My thinking is that room reflections are minimized by asymetrical room dimensions. You seemed to have squared yuor room off.
Waht's the thinking there?

gregadd November 21, 2004 21:08

Albert, assuming everything is correct with both the player and the disk, try this: individually program in each track you want to have included in the repeated playlist, then play that program with the repeat function engaged. Some players seem to have this procedure as a prerequisite for endless repeat, no matter whether the disk is prerecorded or a CD-R.

zaikesman November 18, 2004 05:08

Nrchy, thanks for the offer but too much risk for you. I appreciate your thoughtfulness.

Alex, could be, I don't know. This same disk played with my previous Sony DVD, CD player, including the repeat function.

albertporter November 17, 2004 22:02

It almost sounds as if whoever made the CD-R copy did not 'finalize' the disk after recording it. Such a disk will not play in many machines, but even if it will, you probably won't have any control over track selection or cueing and programmability functions, including repeat play (although it could work normally if played back via a CD-R recorder/player or maybe a computer drive). Yes, it could also just be the machines and the disk is fine, but the chances that two different players would have trouble with it makes me wonder...

zaikesman November 17, 2004 18:47

Albert, I'll send my Sony SCD 777es down for a week. It does everything you need. Let me know if you're interested.

nrchy November 16, 2004 16:04

Digital...it's so problematic!

zaikesman November 16, 2004 05:33

Nrchy. I have the Purist disc and yes, it works better than music at speeding up the break in process.

Problem is, my Sony 9000es will not play it because it's a CDR. I borrowed a Toshiba from a member of my group and it plays CDR's but won't repeat play, even when it's programed properly.

So, If I leave for any reason, I have the choice of constant music or one hour of Purist disc, followed by silence until I return.

When are you coming again? I am ready for you to dine and listen to music with us.

albertporter November 15, 2004 23:58

AP have you tried the Purist burn-in CD? I have found that it really cuts down on the time needed for break-in. I wouldn't be without my brother-in-laws disc anymore! ; )

nrchy November 15, 2004 16:23

Thanks for the positive review of my images Alex.

Nrchy, I still don't have enough hours to have this beast smoothed out. The high frequencies are a bit too forward and deep bass has not shown up yet. As I keep mentioning, the word is 500 hours for break in and I just passed 200 hours.

The best I can do is about eight or ten hours a day of solid music. At some point my wife and son need to get into that part of the house to dine and watch a bit of TV.

Assuming 40 or 50 hours a week, I need 2.5 months to get to the magic 500 hour mark. Wish I could have been playing music that five weeks I was away covering the European and Denver audio shows.

I must say, this new combo of dual VTL 750's mono blocks and dual ATM-3 mono blocks is unbelievably powerful. Volume and dynamics are no longer an issue but finesse and delicacy are.

New tubes purchased from Germany yesterday should help. 16 NOS Mullard Xf2 Blackburn for the Air Tights.

albertporter November 15, 2004 04:51

Hey, all I can say is, the other night we were passing around photos of our Nova Scotia road trip with some friends who dropped by, and if our pictures of seaside cliffs and wooded waterfalls looked half as good in person as Albert's system photos do over my computer monitor, then maybe there wouldn't have been quite as many instances of someone squinting at a picture upside-down and asking, "Now what's this one again?"... :-)

zaikesman November 15, 2004 03:23

So it's up and running! What do you think? This is a very different system than you had, even if the speakers are biggest change. How do they compare to the Soundlabs? Can you hear the boxes? How does dynamic compare to mylar?

nrchy November 15, 2004 03:03

System edited: Air Tight ATM3 added to component list. Image of VTL 750 and Air Tight ATM3 together with Dali Megalines.

albertporter November 15, 2004 01:33

sorry! I may have confused the vtl750 with 1250.

gregadd November 08, 2004 10:37

We might end up with hybrid tube/digital amps...

psychicanimal November 08, 2004 03:35

Well, I did kind of hide behind hp in suggesting that ss had surpassed tubes. It is clear that they both come short of real music. Harry picked vtl 750 as one of the best(nicknamed broomhilda).
The line between solid state has been blurred. I use cj amp and preamp myself. I am sure all of you read audio magazines. You have seen many a square wave. A little research would reveal a square wave for the vtl 750 which I am sure looks quite good. I doubt if it looks as good as the best solid state. Square wave with slew rate can give a good indication of transient reponse. That is how quickly the amp responds to a sudden impulse and whether it rings. I can't draw a picture but the edge is rounded follwoed by spikes that slowly decay. This can idicate audible softening of transients following by a slight ringing.
That being said I prefer tubes. But I admit to compromise. Mr. Porter seems to be going all out. That creates a special dilemma for him.

gregadd November 08, 2004 02:01

Let's face it, tubes don't just sound good, they're a lot of fun in an aesthetic sense (no pun intended re. Albert's [tubed] preamps of choice). One advantage the Megalines should enjoy with tubed power amplification is that they employ many smaller woofers, instead of fewer larger ones. As far as the squarewave response question goes, sqarewaves don't look like music signals.

I happen to use SS preamplification mixed with tubed power amplification myself, so I'm not dogmatic on this topic, but the final arbiter must be the ear and owner preference. Either design approach can have its advantages, and either can sound good, though maybe in somewhat different ways.

In my own system, if anything is ever likely to dislodge the tubed power amps, it may well be one of the new wave of 'digital' power amplifiers, in the interest of maximum efficiency. Recently I made two major purchases: a new Toyota Prius hybrid car, and an ExactPower AC correction unit for the system. The car gives me a real-time calculation of gas mileage; the EP gives me a real-time display of wattage consumed while the system is playing music, idling, or turned off/in standby.

The Prius has made about a 50% reduction in the amount of energy I consume getting from here to there, and that combined with the EP's display has made me much more aware of how energy-consuming running a high-powered audio system can be (in this case, about 800w when playing music loud). The best conventional SS amps I've heard have all operated in class-A, even more energy-consuming (and waste-heat generating) than class-A/B tubes. If I could get sound to make me happy without the size, weight, and heat of regular amps (or the need to change tubes), and consume much less energy at the same time, that could be the catalyst which prompts me to switch. But this still seems like an emerging technology, and I admit I haven't done any auditioning in this direction yet.

zaikesman November 08, 2004 01:15

Reviews? Now were believing reviews?

OK, here's a quote from Art Pfeffer's review of the VTL MB-750 Reference Amps. For those that don't know, he is also with Absolute Sound.

Twenty-first Century state-of-the-art in
performance...   superb image density, the ability to create an almost infinite number of images...

And this one from Wayne Donnelly of Ultimate Audio, also the VTL MB-750 Reference Tube Amplifier.

... Even at moderate volumes these amplifiers
have an authority that in my experience cannot be equaled. The authority is heard not only in the precise and tuneful bass, but all the way up to the very airy top end...

 

And HP's review on the Atma-Sphere tube OTL amplifier. (Golden Ear Award)

Given the right material and the right speaker system (say the PipeDreams), the MA-2 can create an illusion of real sounds that, at moments, are quite uncanny. Its ability to encompass quite wide dynamics
while resolving , during forte and stronger passages, the quieter and more nuanced small dynamics from other instruments, is unsurpassed in my experience.

Combine the dynamics and the clarity and accuracy of its reproduction of fast (and slow) transients, and you reach what I believe to be a new level of realism in home playback.

I could hardly believe my ears.

So reviews say everyone is abandoning tubes for transistor? That’s silly, neither position nor audio review proves anything.

albertporter November 07, 2004 23:56