Psycoacoustics and amps??

[Guest SteveG]

A second question directed to Ken Kantor.

Like many who have come to this site, I am an avid listener but NOT an electrical engineer. I can solder fine but I do not pretend to understand all the technical stuff. Listening is the deal.

However you and others have mentioned some of the relative merits of the 9 versus the LST. And more recently there has been discussion of the Magic speaker which I get the impression does (or was intended to)have the best of both worlds. (I downloaded your article on these but unfortunately much of the text is too faded to read.) Could you elaborate a bit on these differences in lay terms? I realize that ultimately listener preference rules on these issues, but the attraction of a speaker that has it all is undeniable.

I have owned a pair of LSTs since about 1976 and have always loved hearing music on them. Only a year ago did I get enough amp to take them comfortably to what I consider reasonable volume effortlessly. This was when I took the LSTs to the basement and got a used adcom 555. (This was accomplished by replacing the LSTs with a pair of 11B's i the now TV-only room.) The basement room is larger than prior location and has acoustic tile ceiling, rug, and masonry/wood walls. The sound is just wouderful now. The bass response is far beyond what I had experienced before. I didn't reaslize that they had this potential but lacked the amp to bring it out. I have 2 questions on this setup.

1) the impression I get is that the tradeoff of the LST is that precise imaging is sacrificed for the wide dispersion afforded by the multiple drivers. On orchestral music and many jazz recordings I have no trouble placing the separate instruments across the "stage" with eyes closed. Although I must admit this is not of great importance to me. I don't usually get a good enough seat at live concerts to be able to isolate the sound of different instruments by location so I would take this to be almost a distraction if overdone in a recoprding, as was the case in a lot of early stereo recordings. Am I missing the boat here? I auditioned 9s in the showroom in 1978 and again lately and really did not find a substantial difference other than fuller bass in the 9s. Other differences seemed more subtle.

2) there has been a lot of buzz about the adcom 555 and amps of the "bi-polar" design being harsh at mid and high frequencies. I have not done a direct AB comparison, but I am not at all unhappy with what the 555 does to the LSTs. How much real audible difference is there between an adcom 555 and a mosfet design like the newer adcom 5802, 5800, or 5500? All this techno sounds great, but i am not looking to replace a $300 amp with one that will cost $700 or more used unless there is serious aubible improvement.

Your thoughts on these issues would be greatly appreciated.

Thanks

Steve

[Guest]

Steve, I hope you don't mind an uneducated comment or two.

Just so you'll know, I've had a lot of hours spent in front of my dad's 3as and an uncle's LSTs in the same room, then, later, my 9s in the same room (my dad's living-room).

I too enjoyed listening to the LSTs, but the room was just wrong for them. In that room, with the 3a and LST on the same shelves the LST's sounded thin and the dispersion was distracting because of a nearby, interfering reflective surface. I preferred the 3a.

Those same LSTs on a long table against a wall in a really live room at my uncle's house (with no more amplifier) really sang. They sounded like a different pair of speakers. The image in that room was impressive.

My dad's living room has been the only place I've ever had my 9s where they really showed-off and the speaker cabinet simply vanished. In that room the 9s were the clear "winners" and that wasn't exclusively my opinion.

I've concluded for myself that it is going to be a combination of things that are going to let any of these speakers show their potenial.

Bret

[Guest SteveG]

Bret, Thanks for sharing your experience. Sounds right that room environment makes a big difference. Probably also listerer preference and preferred type of music. I know that the AR9's I heard recently, while in perfect shape were running through an multiband equalizer and may well have been set up to owners preference but not mine!! I wonder also how much our preferences might be influenced by our own hearing (or lack of it if too long at rock concerts)??

Steve

[Guest Nigel]

Steve;

I do not think that you would be able to here the difference between a 555 and 5500. You might to the 5800 or 5802 just due to the power increase.

If I were in your position, I would be on the look out for a deal on a second 555 to bi-amp your LSTs.

Nigel

[Guest SteveG]

Nigel, Thanks. So you do not buy this idea that there is a real audible diff between the 555 and the lated mosfet designs?

Re bi amp, do you mean bridging both amps and using one on each speaker? The inputs in back of the speakers have only 2 posts so I cannot power the woffers separately I assume. I assume that the design is for the only a single amp driving each speaker.

If I get another 555 and briged both, what does that do the characteristics of these amps? Are they still as stable at low impedance?? Is distortion or anything else materially affected? With the 555 rated at 325 watts per chanel at 4 ohms in dual mode, I seem to recall it is rated at about 600 per at 4 ohms when bridged. Is there any way i which this can be too much power and potentially harmful? Or is it the general opinion that the more power the better so as to avoid distortion at clipping, the real enemy of drivers??

Thanks

SteveG

[ar_pro]

The vertical bi-amp setup is a nice way to go, and you don't need to bridge the Adcom amplifiers. First, disconnect the jumpers between the woofer section and HF section on your speakers. Then connect one channel of amplifier #1 to the woofer section of one 9, and the 2nd channel to the HF section of the same speaker. Repeat for the 2nd speaker and amplifier - this means two (2) sets of cables from each amplifier, to each speaker. Your preamp will need to send a LEFT signal to both channels of one amplifier, and a RIGHT signal to both channels of the other...if your preamp doesn't have the extra L&R output jacks, just use a "Y" connector on each single preamp out, to provide the extra jacks. I used this set-up with a pair of Adcom 555II amplifiers, and it was very, very impressive. I was also able to use a low-frequency equalizer to adjust the 9's low end without effecting the mids and highs, by sending its signal to the woofer channel of each amplifier.

[Guest Nigel]

HI Steve;

As ar_pro says; vertically bi-amp. I have not seen the connections on the LST, but am assuming that they are like most other AR speakers before and recently after that era, with three terminal, two off them connected together: 2 & T.

To verticall bi-amp, disconnect the connection between 2 & T, connect one to each + output of the amp, connect the common terminal (1) to both - outputs.

This also works on the AR3, AR91 and others.

See:

http://www.arsenal.net/speakers/ar/ar-3a/AR3aXorig.gif

Nigel

[Guest SteveG]

Nigel and AR_PRO,

Thanks for advice but alas, the input terminals on the LST (or at least my LSTs) are not a 1,2,T like on 3a, 5, 6 and even 4x models. They are just 1 and 2 with red and black twist caps, but I just connect with banana plugs thru the center of the caps. So the kind of biamp you suggest will not appear to work. That is why I asked about thoughts on bridging. What do you all think??

Steve

[fedeleluigi]

Hi Steve

You are right, it's not possible to bi-amp LST becouse of their auto-transformer that is common for woofer, mids and tweeters.

Luigi

[fedeleluigi]

Hi Steve

you could try to listen to one speaker only driven by only one channel of your adcom operating in stereo mode first and then by your amp operating in bridge mode.In order to use only one channel when your amp is operating in stereo mode, disconnect one of the two connection between your cd player (or turnetable) and your preamplifier so that no musical signal will arrive at one channel of the preamplifier and amplifier.

I think that if you do not use too much power when tha amp is operating in bridge mode everything will be ok. In this way, listenig to only one speaker, you can see if there is any improvement when your amp operates in bridge mode.

[Guest]

>Sounds right that room environment makes a big difference. Probably also listerer preference and preferred type of music. <

Sure, I mean, that goes without saying and so I wasn't really trying to be Captain Obvious even though, when I re-read what I wrote I sure came across that way, sorry.

I think what I must have had in mind when I was replying was to make the point that it would be impossible to know what each amp was going to sound like unless they were in your room with your speakers. Am I doing Captain Obvious again?! Sounds like it.

Tell you what - I'm going to go quiet on the issue and spare myself lot of embarrassment.

Just one last loosely connected thought. One of the things I really, really, appreciate about AR speakers is that E Power Biggs playing Bach on a pipeorgan, Vivald's Alla Rustica (sp?), Bing singing "White Christmas," Devo doing "Whip It," Michael Hedges playing a "harp guitar", CS&N getting folksy, and Judas Priest doing whatever, all sound terrific.

Bret

[Guest]

>So you do not buy this idea that there is a real audible diff between the 555 and the lated mosfet designs<

I wanted to revisit this a little bit so had to dig around for this message.

I've recently become the new owner of an old Luxman CL35 MkIII preamplifier. Tubes, although I'm not sure where they are in the circuit. (I've been busy since I got it and haven't looked yet.)

I'm thinking that those are probably "output" tubes. I know that everyone does it the other way around, but with a tubish preamp and a "harsh" amp, I still ought to get an acceptible sound.

I don't think I can spring for a 5800 series Adcom amp.

Think a 555 and this tube preamp ought to sound okay together?

My thought was "one 555 now and another later."

AR9 speakers.

Bret

[kkantor]

1- If two solid state amps of comparible power sound different, then one or both of the amps is broken. Properly functioning amps do not sound appreciably different from one another, at least different enough to change the sound quality in a system to any real degree.

I am beyond the point where I will even respond to flames on this subject. It is just plain nonsense.

2- I will re-scan and post the previous article. It's too big a subject to cover without background.

Ken Kantor

www.intelligentaudiosystems.com

[kkantor]

Hi,

Unfortunately, the copy of the MGC-1 article I have around is also unreadable on the first page. Somewhere I have the real original, and will post it here when it turns up. Meanwhile:

1- I already answered the amp part of your question, I hope.

2- Concerning the LST vs. the 9... two of my alltime favorites, in totally different ways.

I saved up for used LST's as my first "serious" audiophile speaker. (Before that, University, Dynaco A25, 2ax, homemade, etc.) My original plan was to get used AR10pi's and put a Microacoustics tweeter array on them. This was a fad for a short while. But the dealer got a set of used LST's first, and I jumped.

Later, my first pro contact with AR was working part time (as a student) for the Advanced Development Division a few months before the 9 was buttoned up. I subsequently worked on the 9D, a fully active version designed for the futuristic concept of "digital audio." The 9D group basically turned into NAD, but that's a whole different story.

Anyway, that was my first exposure to real audio R&D excellence, and it has remained my benchmark since. Marketing wasn't shabby either. Julian Hirsch tested the speaker, found a slight rise in the tweeter, and trusted AR so much that he literally blamed his microphone in the text of the review. We didn't mention that we found the same slight rise....

Anyway, long intro, short, simplified answer:

1- Splash sound all around the room, shoot for constant power response. Really good, smooth tonal balance. Lush and involving envelopment. Fantastic on good orchestral recordings and sparse chamber music and jass quartets. Poor transparency and imaging, some vocal coloration, due to all the reflections you create. Low efficiency, due to the need to push air in all directions. LST is an extreme example.

2- Keep the on-axis first arrival clean and flat. Really detailed and powerful sound, great imaging. Less envelopment and immersion. AR-9 set the standard for its day, plus had just about the best bass ever to be heard before, during or since.

3- MGC-1... later, after I can find either the original AUDIO article, or my AES paper on it. Maybe I can get the AES paper in PDF directly.

Ken Kantor

www.intelligentaudiosystems.com

[Guest Sean]

>1- If two solid state amps of comparible power sound

>different, then one or both of the amps is broken. Properly

>functioning amps do not sound appreciably different from one

>another, at least different enough to change the sound

>quality in a system to any real degree.

>Ken Kantor

>www.intelligentaudiosystems.com

It is sad to hear that someone with as much experience and the reputation that you have could make such a short-sighted and irresponsible claim. I would think that it would be quite easy to understand something of this nature with your technical background. The differences in amplifier design with the resultant variances in circuit stability under reactive and dynamic conditions are primarily what account for the differences in sonic characteristics from amp to amp. This is quite apparent if you've ever taken electrical measurements and studied the results.

Even Frank Van Alstine, who is widely known for being a "wire is wire" type of guy, has publicly admitted that speaker reactance and amplifier stability can go so far as to "modulate" the power supply of an amplifier. He has also stated that high levels of reactance and the resultant load that the amp sees at the speaker terminals can actually be transferred back and measured at the input terminals of the amplifier. As such, if you CAN'T hear the difference in sonics with various amplifiers connected to the same load, the amps are either 100% unconditionally load stable ( ha ha ha ), not functioning properly or the rest of the system is not revealing enough to disclose such differences. The only other alternative is that one can hear but lacks listening skills.

Part of this whole situation was resolved many years ago. Nelson Pass even went so far as to document the differences that speaker cables make on the sonics / performance by measuring the signal transfer characteristics of various cable / speaker combos. He did this because people were experiencing various levels of electrical performance / sonic variances with different amplifiers and various speaker cables / speaker combo's. He wanted to know what was going on electrically and therefore studied the situation in a scientific manner. The results can be viewed by going to the website listed below and clicking on the "Speaker Wire: Science or Snake Oil" article to download it. There are plenty of pictures there that visibly demonstrate the variances in loading that amplifiers run into and are forced to deal with on a system by system basis. As mentioned, the load that the amp sees changes on a note by note basis since frequency, amplitude and reactance change due to the dynamic nature of music. As such, do you think that ALL circuits measure and sound the same into any given load at any given time ?

Nelson's bottom line: System synergy is what is most important. The best results may not come about via the components / cables that you think might serve you best. Sean

>

http://www.passlabs.com/articles.htm

PS... I hope that you don't take this as a flame, but as a contrasting point of view.

[kkantor]

"...short-sighted and irresponsible claim..." is not a flame? You could use some introspection.

No, my statement was carefully worded, carefully considered, and based on decades of direct experience and professional study. I stand by it 100%.

To the extent that any "fact" exists in science, my position stands as a very widely accepted (in professional circles) fact. Assertions by fringe "audiophile" designers remain marginal, speculative theories that never prove themselves in any kind of unbiased situation, year after year after year. Like the Raelians do, they ignore the vast body of evidence from disparate sources, and remain convinced of very far-fetched concepts.

Sure, you can build an amp that sounds "different," and many companies do. So? It isn't about "synergy." It's about engineering and knowledge. I have been open-minded and interested enough to research this subject for YEARS. You, on the other hand, make casual, unwavering assertions and seem firmly convinced by dubious hype. Your loss.

Incidentally, I published that stuff about reactive load behavior in 1986, and I wasn't the first. However, my work was subsequently reprinted and distributed by Monster Cable, with permission and under my byline. If you don't understand how the phenomenon that Van Alstine refers to is totally compatible with my statement here, perhaps you should ask some questions.

Buy whatever amp you want. You will either get an amp that is audibly indistinguishable from hundreds of others, or you will get an amp that is more grossly damaging the signal. Up to you.

[Guest SteveG]

Ken,

Thanks for the response. Your purchase of used LST's is very similar to my story.

Looking forward to hearing more about the MGC-1.

SteveG

[kkantor]

Sean,

I wanted to make a few clarifying points. I think you should re-read Pass' paper again. The paper does not specifically address amplifiers in any meaningful way, so it's citation is a bit of a stretch in any event. Further, it is an ENGINEERING document, and does not follow any kind of scientific method or control. Surely, there must be peer-reviewed, published documentation on amplifier audibility? It is a subject which has been widely studied, and for which a positive outcome would have significant economic benefits to many manufacturers.

Most important: Pass' paper never deals with audibility. In fact, he ends the paper on a very cynical note, basically saying, "Sure, buy expensive cables, whatever. Not a real issue." I can't begin to tell you how many manufacturers have conducted fruitless internal efforts to prove that their amps sound better. Audiophiles are very defensive on the matter, but people just cannot hear the differences they believe they can. On any system. Any way. Unless the amp and speaker combo is pathological. Which is very rare with decent transistor amps. To quote Gordon Holt, "Don't like the sound of your CD player? Move your speakers a few inches."

[Guest SteveG]

Ken and Sean,

Interesting discussion. I feel a little bad having possibly kicked it off. But I have to reiterate that I could hear absolutely no real difference between Adcom 555 and Adcom 5802 on the LSTs even at very high volume. I was fully prepared to hear a difference and EXPECTING one. Had read many reviews extolling the virtues of the 5802. So I was surprised to hear no difference. And I tried a lot of different types of music going back and forth between the amps. Perhaps this means the the 325 watts per chanel at 4 ohms from the 555 is enough, and the additional reserve of the 5802 was untapped in my listening. But in any case, the SOUND of the music was really indistinguishable. I would add that the SOUND really was different between these amps and a Pioneer receiver supposedly rated at 100 watts per ch at 8 ohms and 0.09% THD. The pioneer just couldn't seem to satisfy the speakers and create the full sound the bigger amps get. This is most noticable in the bass, but also at higher frequencies.

SteveG

[kkantor]

Don't feel bad... this is a germane and important subject and we are all volitional creatures here. I assume. I never jump into a subject I don't want to.

Your impressions seem correct to me. The Pioneer would have trouble supplying enough current to the LST's demanding load, and might not deal well with the autotransformer. It probably delivers 30 or 40 Watts in practice. Neither Adcom would have such a problem. If you get a chance to try another decent amp, do report back....

[Guest Nigel]

>5802 on the LSTs even at very high volume.

SteveG;

My experience, is that I can tell a bigger difference at LOW volumes than at high volumes between moderately powerful amplifiers, and high powered ones. At higher volume levels it all seems to blend together.

Nigel

[Guest SteveG]

Nigel,

I Really could hear no discernable diff on LST's between 555 and 5802 at any volume level. I agree, however, that the diff between the Pioneer and the Adcom(s) was apparent at low and high volumes. It seemed greated to me at high volumes, perhaps because I instinctively held back from very loud volume with the Pioneer. Regarding the sould all blending together at higher volumes, I have found this really not to be the case with the LST's, while it is so with other speakers I have listened to. The exception on the LST's in my experience is a recprding where higher frequencies are not recorded very well, and higher volumes become hard to tolerate. I assume these are recordings where the microphome was overwhelmed or something that distorted the highs. But on really well recorded material, I have found that the LST's retain clarity up to VERY high volume. I do of course stay below the ear-pain level of course.

steveG

[Guest Sean]

Pass' went so far as to say that using a set of speaker cables with the specific speakers being used would cause the amplifier to shut down. Swapping cables with the same loudspeaker load then resulted in normal operation. He ran into various situations between these two extremes with the multiple cables that he tried and measured. Unless one suffered from hearing loss, the amp going into break-up, oscillation and shut down should be readily audible. Obviously, this is an extreme example but it just goes to show that amplifiers can and will alter their performance when various loads are thrown at them. There are very few amps that i would call "unconditionally stable".

As far as Monster Cable goes, they are the "inventors" of snake oil and high profit margin when it comes to wire. I would not be too proud of any affiliation with them or the fact that they may have used your opinion to further the sales & marketing of their products.

As far as the audible differences between amplifiers go, David Spiegel, who was the "inventor" of controlled listening tests using high grade A/B switchboxes and designed what was surely the most advanced preamp of that era, held such tests and invited every "golden eared" reviewer that he could think of. He did this because he wanted to prove that the differences in well engineered preamps was NOT audible. Very few reviewers came to this "listening challenge", probably for fear of failing under the spotlight. Enid Lumley did show up though. In case you don't remember, Enid was HIGHLY ridiculed for claiming to be able to hear ant's pissing, spiders coughing, etc... The bottom line was that Enid was able to discern what products were being used during the A/B tests. As such, she was able to prove David wrong using his own tests and equipment as points of reference. This is NOT hear-say, as it came to me right out of David's mouth.

On a different occasion, J. Peter Moncrieff was able to discern whether or not there was a switchbox in series with the system or if it had been removed. He did this 10 times out of 10 with 100% accuracy in front of a group of witnesses. He did not even have to compare components. Just putting the silver plated contacts of the relay into the circuit was discernable to him. He obviously knows how to "listen" and not just "hear" the obvious things.

I'm not saying that i have ears like either of these people, but it cracks me up when engineers / manufacturers / salesmen make statements about "absolutes". The only absolute in audio is that there are NO absolutes !!! Sean

>

[kkantor]

Sean,

You're a funny guy! I like you. I also deal with 10 robotically militant "audiophiles" every week of my life. People who cite Lumley and Moncrieff don't ever change their minds. They are like survivalists, who see this as a cause or crusade, rather than a learning experience. The more the rest of the world moves on, the more tenaciously, self-assuredly and loudly they proclaim their knowledge. They vilify those who have moved on (Gordon Holt, Corey Greenberg, Peter Aczel, Polk, me, etc), while deifying the most ridiculously extreme caricatures the industry has produced (EL, PM, etc.) These are people who hear bugs. Who think "digital" causes stress. Who hear the generators in the power plant superimposed on the house current. So I'll give this one honest and sincere try, then leave you to your religion. Hear me now, and disbelieve me forever:

The notion that anything in the world is a continuous function is a human conceit. Fundamental energy quanta exist ONLY at multiples of the Action. Particles have names, combinations and boundaries. Atoms and molecules are stable and characteristically identifiable. The digital sampling theorems of Nyquist and Shannon are truths, not speculations. Etc. What this leads to is that the human perceptual system does not respond to a continuum. It is based on thresholds and stochastic responses. Just because you can measure something doesn't mean anyone can hear it. Just because some amps break down one way, and others break down another way, it simply does not mean that all amps lie audibily in between. That is a logical fallacy, on the face of it.

Also,

Actually, I am particularly proud of the Monster deal. The research I did was good, solid. And I figure if one can get paid well by a cable company, saying the things I have been saying, one is doing pretty well. Plus, it is clear to most in the industry that vast regions of the "high end" (press, dealers, manufacturers), owe their existence to MC.

Have fun with your obsession. That is one thing obsessions are good for.

[Guest]

>You're a funny guy! I like you. <

Uh, Ken, I, uh. . . well, I'd better keep my day job and not try to go into a comic routine, here.

I want you to know, for sure, that I'm a "wire is wire" kind of guy. I'm a "you can't possibly hear that!" kinda guy. I'm skeptical.

But Ken, amplifiers do sound different. How can I tell which is broken?

The friend of mine, Don? I took my Adcom 555MKII to his home. I also took 4, 15' lengths of 12 gauge wire, banana plugs, an old SAE 2900 preamp and an Adcom GTP-740 preamp. He already had a Threshold A400 amplifier.

This may definitely be a case of "I don't know much about art, but I know what I like." Or it may be my fault for too broadly interpreting your earlier remarks.

When we were A/Bing amplifiers we weren't really A/Bing them because it wasn't strictly possible. There was *at least* 5 minutes between amps.

I do not recognize any of the names that you or Sean are talking about. I was never an avid reader of Stereophile, have never claimed "golden ears," and don't pretend to be able to explain why or even quite what is different about using 10 gauge wire or 18 gauge over short runs. I doubt I'd understand it if you explained it.

But...same input, same wire, same speakers - The Threshold amplifier is heads and shoulders better sounding (to my ear, Don's, his wife's) than my Adcom with either the SAE or Adcom preamplifiers. The "soundstage" moves a foot beyond the back wall with the Threshold, a "ringing" string rings more true, and most startlingly, there is a whole "tone-shift-thing" going on making the speakers sound brighter with the Threshold.

Something is different.

The Adcom is "punchier" but the soundfield is close-in to the speakers - less transparent.

Soooo, which amplifier is "mangling" the signal? Am I temporarily fooled into believing the Threshold is better-sounding by some weirdo phase thing going on in the Class-A design or is the Adcom broken or. . . what? The difference is astonishingly easy to hear even after 5 minutes of silence. But either amplifier towers over a less powerful receiver at any given volume with either preamp.

We switched back and forth several times because it was both of our expectations that we would hear no difference between the amps. When we did, instantly, we had to go back and forth just to be sure we weren't talking ourselves into hearing something that wasn't there. What we heard differently we both heard. What I described as differences so did he.

Can you help me reconcile the truth in "an amplifier amplifies" and the truth I heard with my own ears?

Bret