Warming up, burning in, diffusing, firming up

[garyrc]

Two separate questions, that might have different answers:

I. Have you noticed a subjective improvement in your sound after doing any of the things listed below?

II. Can you refer me to any articles that describe testing of these notions under controlled and blind conditions?

1) Warming up solid state equipment

2) Burning in speakers, electronics, or players for many hours

• With a burn-in disk?
• With music

3) Placing a few diffusors (an affordable, therefore small, number -- like 4, 5, or 6) strategically on the walls or ceiling.

4) Firming up audio racks, or buying more massive or "better" ones (I'm excluding racks that hold turntables or tube equipment, since I already believe that those components are sensitive to vibration).

Thanks

[djk]

Years ago I serviced a big Mark Levinson amplifier.

It sounded great after it warmed up (30 minutes or so).

While it was warming up it had no stereo image.

There were different brands of resistors in each channel.

A similar story could be told about a Conrad Johnson piece that took 45 minutes to warm up and sound good, but it was tubes (so that really is to be expected).

Some people can hear the differences in short pieces of wire, others don't .

The people that don't hear seem hell bent on proving the people that do are delusional.

Which camp are you in?

[russ69]

I. Have you noticed a subjective improvement in your sound after doing any of the things listed below?

II. Can you refer me to any articles that describe testing of these notions under controlled and blind conditions?

I keep subjectively improving my system under uncontrolled conditions. My systems get better and better, I use my ears and listen. So far it's worked pretty good. I don't need to hide an amp behind a curtain to find out if the amp sucks.

Thanx, Russ

[artarama]

Can't help with any articals or controlled testing but I do believe! 100%

Some of it may be your ear "tuning in"

I don't like to waste any more energy than the next guy but I will turn my equipment on and let it warm up for a while before I go down to listen. System stabilization? Who knows. All those electrons get pretty excited about going to work.

It may have something to do with each filter/cap. etc. reaching some sort of thermal equilibrium. Not sure but I believe it.

"I think therefore I am."- Rene Descartes

[artto]

Warming up is different for different types of components. Can you tell the difference on, say a common $20 table clock radio after its been on for an hour vs. just turned on? I can tell you as a matter of fact, that on my Luxman MB3045 it takes approx 63 minutes to properly warm up. I've timed it ~ blind ~ and its the same every time, 63 min. But here I can also see it/measure it. When biasing these amps (tedious at best) you can actually watch the bias voltage swing up & down when the DC balance is adjusted & vice versa. It keeps swinging back & forth for sevreal minutes until it settles in. It does this even more on a cold startup. After 63 minutes everything stablizes, locks in, and its like a camera lens coming into focus or removing the glass and screen from a window opening. The bias and DC balance also stop fluctuating and "lock-in".

Same thing goes for burn-in. Many electronic components, especially high-end stuff, gets a burn-in at the manufacturer. They do this primarily to weed out bad components as most component failures for defective electronic parts will usually occur in the first few hundred hours of operation. As for breaking in or burning in things like cables, IMHO its nonsense. In fact, there's a school of thought that says the more you use your system, the more everything (including cables) become magnetized by hysteresis and therefore need to be demagnetized (which might imply that burning-in cables is actually bad because all you are doing is magnetizing the cables which will then need to be demagnetized). It's a vicious circle.

Take phono pickup cartridges for instance. The Decca I have is very low compliance (stiff). It also has a rather unorthodox mechanical assembly with no cantilever in the conventioanl sense and includes a tie-back string (no kidding). This device needs some break-in. Other pickups that are very high compliance may sound their best right out of the box because the cantilever suspension tends to fatigue and harden over time (even without use).

On musical instruements, strings for instance. Some players might like the sound of fresh strings and change them for every performance. Others perfer their strings "broken-in" a while (maybe 20 hours) so that some of the "clang" is gone providing a more mellow tone. Some prefer to never change the strings if they can avoid it.

Me, I try not to waste time worrying about it anymore and just get down to listening to the music ~ except for a warm up on tube equipment ~ and that also depends on the device (Luxman MB3045 = 63+ min. / Wright 3.5 mono = 30min. or less etc)

[artto]

and the diffusor thing.......less is less. If you are experiencing a particular problem at a particular location, your spot treatment approach may solve the problem provided its confined to middle/treble frequencies. However, most acoustical problems also involve the bass range which is aprox half of the audible musical spectrum. Devices which are large enough to affect the bass frequencies will also affect the higher frequencies (this is called "broadband") and is really the way to approach an acoustical problem, not by attempting spot treament of specific frequency ranges in very small surface areas.

[Don Richard]

The only type of solid state amp that may need a warmup period are Class A amps. They run hot and may need to thermally stablize to realize optimal performance. Any other solid state amplifier that is not defective should be ready to go seconds after turning it on.

[garyrc]

Thanks, everyone.

I'm still interested in more replies, esp concerning any controlled tests that have been published.

As to which camp I'm in, I vacillate ,,, which is part of the reason for my questions. ...

and, of course, it depends on the type of component we are talking about. I tend to doubt that there is a difference between audiophile wires (unless extraordinarily long), but I have heard about changes similar to the ones Artto mentioned after wire is used for a very long time. What I heard was that wires become more directional with use, so if you take down your system and set it up again, you should mark each cable and speaker wire, so you can put them back with the electricity flowing in the same direction. The dealer & technition who told me that was not in favor of the famous interconnects that have an arrow on them, showing direction of flow, if they were made a certain way --- i think they had one of the leads (the shield ?) connected at only one end of the cable -- because he thought they caused ringing.

I would like to trust my ears, and often do .. it's my default position ... yet a dealer and I and a couple of spectators fooled ourselves repeatedly as to which amplifier was playing in a paired comparison with the volume well equalized with pink noise and a meter .... and the noise also sounded equal to our ears ... but when the music was playing, we thought we could tell the difference between amps, but we made many errors.

The reason I'm interested in controlled double blind tests, is that, while it is very difficult to establish that something doesn't ever happen (and perhaps philosophically impossible to demonstrate), good, well designed, replicated, studies that do show a difference between procedure A & B, or component A & B, that are significant at, say, the .05 level or beyond, would pretty convincingly show that the difference can happen without the uncontrolled presence of extraneous or confounding variables (but not that it would happen under different circumstances).

I am quite aware of the arguments that A-B double blind testing may not be generalizable to usual listening because our brains might not be functioning in the same way when making judgements (direct comparisons between A & B, "different or the same?" "better or worse?" "more realistic or less realistic?" "more or less like the reference?") as when just listing to music in the long term without direct comparison judging ,,, just leting the music wash over you in your favorite way. I suspect that well designed A/B test would have high internal validity, but somewhat lower external validity.

It might be interesting to build a variable of "listening mode," with levels of "judging direct comparisons" and "just listening" into a multivariate design and analyze them.

Then there is the problem of adaptation .....

So I'm interested in both the subjective experiences and the controlled tests that are out there.

On diffusors for a ceiling that may end up sloping from 7' 8" to about 8.5 or 9 feet: I like a "live" sound, but dislike spectral reflections ... if I buy a few expensive ones for the first reflection points, can anyone recommend inexpensive ones to scatter around the rest of the ceiling?

Gary

[russ69]

I've been in this hobby a long time. I have found no usefulness with short term listening demonstrations especially in systems other than my own. I have only found satisfaction by long term review of components in my own system. Blind testing therefore is not useful for me, it's too limited. If you find satisfaction by using the opinion of others in a blind test environment, that's fine but logistically limiting. Furthermore I do not need the agreement of test sampling to know whether I like what I'm hearing in my system as I am designing my system to suit me not satisfy the group mentality.

Thanx, Russ

[seti]

Music sounds better when my state of mind is warmed up and burned in [H]

[artto]

I'm old school. The only thorough double blind test I thoroughly recall is the infamous Stereo Review test back in the 80's. They compared a wide range of amplifiers, everything from a lowly common Pioneer reciever all the way up to a $12.000 ($198?) Futterman OTL power amps.

http://webpages.charter.net/fryguy/Amp_Sound.pdf

The conclusion, not much difference, except for maybe the $12,000 Futterman.

A few years ago Klipsch was conducting A/B/X blind tests on speaker cables.They had a control unit that kept track of the listener's scores. Forum Administrater Trey Cannon can probably fill you in more. As I recall, something happened to the result data. I actually did very well on the test, until, as with all of us, we become so focused on trying to tell the differences that our ear-brain processing becomes fatigued, and then of course the tide turns and ther results resort back the mean (average).

The dealer/technician that told you about the directionality of cables after long time of use sort of confirms the hysteresis thing. How much it affects the sound is another matter. Sheffield Labs ( a reputable source IMO) had a CD out which supposedly demagnetizes the cables and other equipment. This CD is also available from XLO I believe.

IMHO, if you want a real "test" of how good a playback system is, it should be compared with the original sound. This is often not an accessaible alternative for most people. Fortunately for me, it has been, and I can honestly say that myself, and friends have been fooled by the playback from my system, thinking it was "Bill" speaking or playing his banjo when he wasn't speaking or playing at all (while we were recording in same room).

Longer term listening has its own benefits. IMO primarily because one doesn't focus so much on such small time intervals and become fatigued quickly. Over time, on various recordings, different moods you're in, whatever, other things slowly become apparent.

Regarding acoustics, if you've got a sloped ceiling you'rve already got a good start. Curved surfaces are better for diffusion that flat sloped/angled ones are. Convex is better than concave which can actually make acoustics worse. The only good diffusors that are small that I know of are called diffraction grate or space couplers. RPG Acoustics has some and I think Auralex has some similar stuff now. BUT they're not necessarily "inexpensive" ~ it's all relative.

http://www.rpginc.com/residential/index.htm

http://www.rpginc.com/residential/cinemusic-products.htm

[artto]

Music sounds better when my state of mind is warmed up and burned in

That ALWAYS helps!!! And we all know what that means [:#]

[]

[garyrc]

"Furthermore I do not need the agreement of test sampling to know whether I like what I'm hearing in my system as I am designing my system to suit me not satisfy the group mentality.

Thanx, Russ"

As I'm sure you know, (well designed) double blind testing can be used to protect a given individual's judgements from the influence of certain extraneous or counfounding factors, like knowledge of which component is actually playing, the appearence or reputation of the component, etc. True, I'm much more interested in what I think a component or system sounds like than what a group thinks ....but I'm more interested in what my ears tell me in a controlled environment than in a contaminated one. Since I don't have access a wide range of equipment and don't have a staff to manipulate the independant variables while I listen, I'd be interested in results of controlled studies, whether they use group or single subject designs.

I suspect that some of the results of "open" v.s. "blind" comparisons that occur with groups also occur with individuals, perhaps even me and thee. One old study (which I can't find right now) with groups found that when the participants knew which speaker wire was playing ("open" condition) they "heard" significant differences between the wires, and had preferences. In the blind condition, the only differences they heard was between the Radio Shack "speaker wire" -- thin stuff meant to go through walls (not today's version) and any an all of the audiophile wires. The most interesting results were that when blind: 1) They could not reliably distinguish between the audiophile wires, and therefore had no favorites among them 2) Even though they could reliably hear the difference between the Radio Shack wire and the audiophile wires, some liked the Radio Shack wire better!.

[russ69]

I'd be interested in results of controlled studies, whether they use group or single subject designs.

Read the Dr. Bose thesis, he's well documented on blind testing using large samples, the only problem is you get a pair of Bose 901s if you follow that philosophy, no thanks, been there.

Thanx, Russ

P.S. I'm not interested in a cable discussion, if you can't hear a difference, why do you need a documented study? Just use what you have and be happy.

[garyrc]

Thanks, Artto. Very interesting. THanks for the links.

The RPG Hemifusors (like Auralex Space array) are pushing $700 a pair for wood, which means I would only buy a pair, which probably wouldn't do much. Their "molded" ones are less, so I'll request a good color photo to see if they look too much like plastic.

Read the Dr. Bose thesis, he's well documented on blind testing using large samples, the only problem is you get a pair of Bose 901s if you follow that philosophy, no thanks, been there.

Thanx, Russ

P.S. I'm not interested in a cable discussion, if you can't hear a difference, why do you need a documented study? Just use what you have and be happy.

To my ears (under conditions that were not controlled), the BOSE 901 may obscure some details, compared to Klipsch horn loaded speakers. I will try to look up Bose's work, though.. I predict I'll find that he didn't compare his speakers to good horn designs like Klipsch, JBL, etc. The only BOSE 901s that i've thought sounded good are the ones that run non-stop in Alfonso's Mercantile in Mendocino Village, CA -- they have a good sense of body, but Alphonso has always used very powerful amplifiers, > 1,000 wt McIntosh last time I was there. BOSE speakers like big amps, IMO.

I only mentioned the cable study to show what can happen in Open v.s. Blind conditions. If it happens with cables, then I'll bet it happens with less perfect components, especially transducers.

[dBspl]

I would recommend searching Tom Nousaine, Dave Clark and Stanley Lipschitz. I believe they have all published reports/papers on blind A/B (A/B/X) tests they have performed.

I don't think it's correct to say that non-believers are out to prove that people that claim they hear differences are being delusional. On the contrary, I believe the most professional test administrators would welcome a blind test that statistically proved an audible difference. Under these circumstances it gives the technicians and engineers something to go back and analyze and assess. That's really the only way I see to make some headway and maybe lead us out of this stalemate. Unfortunately, whenever these tests are given, the results almost always seem to come out negative, or at least inconclusive. This could be why people that believe they can hear these differences appear to be the target of the people administering the tests.

I might also add that I really don't think the burden of whether something is audble or not should be placed on the non-believers. I mean, why should they have to prove something is audible when they don't claim to be able to hear it. That really doesn't make any sense. Isn't the burden more appropriately placed on the person making the claim?

I've taken a lot of these tests, and while I don't claim to be a particularly well trained listener, I have had a lot of listening experience. I can't tell you how many times I taken an A/B/X test, and when switching between A & B, I thought I could hear a subtle difference. But as soon as I selected X, any difference I thought I heard simply evaporated.

dbspl

[WMcD]

http://www.amazon.com/Sound-Reproduction-Acoustics-Psychoacoustics-Loudspeakers/dp/0240520092/ref=sr_1_1?ie=UTF8&s=books&qid=1267065783&sr=1-1

That is Dr. Floyd Toole's book which is as scientific as it gets on rooms and speakers. It is well worth having in your library. Dr. Toole's work is not so technical that you need much math. OTOH, he is presenting a very long thesis with in a thorough way..

It is worth noting that Toole divides up the effect of rooms and treatments to below and above 200 Hz. Below we have bass modes and standing waves. Above we have dispursion. Not to argue with Art.

- - - -

As far as ABX testing of speaker wire. I've told this story before. It was IIRC during the first Pilgrimage to Indy. At that time Klipsch was hawking Monster Wire. There was supposed to be an ABX shoot out with MW and anything (something) else. But by the time the system was ready on Saturday morning, the MW had been withdrawn.

Often ABX is run with music. My thought was that music is too hard a subject in that you're switching between succesive segments. You're not hearing the same phrase. I happened to have a CD with a pink noise so I used that. The wires IIRC were zip cord versus woven CAT-5.

There was no reason to continue very far. Both sounded the same. It makes me wonder about the source of sound issue in any ABX. Maybe they should repeat just 5 seconds of music.

- - - - -

My suspicion is that proponents of controversial tweeks or amp improvements have sometimes tried ABX tests in private and found no difference. Then they withdraw.

- - - -

To some extent some of these subjects are like the Loch Ness Monster, Big Foot, Flying Saucers, or Alien Abductions. Plenty of reputable scientists would love to find hard evidence necessary for the logic of the thesis. That evidence includes family units, dead bodies, hardware, or a chip in someone's head. . None can be found.

- - - -

Wm McD

[Arkytype]

Toole's writings should be required reading for those who want to know the correct way to set up and conduct controlled listening tests.

Subjective and objective measurement of loudspeaker performance: A collection of papers, now out of print, dispels many myths of what constitutes the "perfect" loudspeaker. It should come as no surprise to Klipsch loudspeaker owners that (to poorly sumarize this "Bible") a loudspeaker with the flatest, widest bandwidth is preferrred over loudspeakers that suffer in these performance areas.

Lee

[russ69]

a loudspeaker with the flatest, widest bandwidth is preferrred over loudspeakers that suffer in these performance areas.

That sounds like the right idea but it doesn't work in the real world. A speaker that works very well but has limited bandwidth sounds better than a lesser speaker that is trying to run the drivers/systems outside of their best performance area. In other words, errors of omission sound better than a speaker that doesn't get a certain frequency right. Mini-monitors are the best example of this. There are many many hi-end mini monitors that sound perfectly wonderful but have limited frequency response. I agree with you about Klipsch knowing this because most Klipsch systems fall short in low frequency and high frequency extension but still sound perfectly acceptable.

Thanx, Russ

[artto]

That is Dr. Floyd Toole's book which is as scientific as it gets on rooms and speakers. It is well worth having in your library. Dr. Toole's work is not so technical that you need much math. OTOH, he is presenting a very long thesis with in a thorough way..

It is worth noting that Toole divides up the effect of rooms and treatments to below and above 200 Hz. Below we have bass modes and standing waves. Above we have dispursion. Not to argue with Art.

To some extent some of these subjects are like the Loch Ness Monster,

- - - -

Wm McD

"Not to argue with Art"?

What's to argue? The large open cell bass traps in corners handle 200Hz and below, and the polycylindrical diffusors above (actually the larger diffusors are large enough and deep enough that that they will affect down to about 100Hz).

It should be interesting when I get around to back filling the poly's with rigid Roxul. My "theory" is that it should help absorb more mid/treble at very loud levels by capturing more reflected sound as it gets behind them while still retaining the live ambience heard at lower levels, and improve performance as a bass trap overall.

The Loch Ness monster has been admitted to be fraud. I wonder how long it will take the snake oil audio companies to do the same? My favorite snake oil right now are these POS

http://www.mayaudio.com/cat.asp?CatID=54

I really don't understand how people who think of and sell these things can sleep at night. I guess it must be because they come in three different colors. LMAO