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post #91 of 2598 Old 06-14-2011, 12:08 PM
 
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Originally Posted by Gizmologist View Post

For some reason pro grade amps seem to be getting a "cheap" label by some here. If you think about it, the pro guys will want a reasonable expenditure for acoustically accurate, high power, long life, low maintenance, performance as when (if) we have an amp fail, the cost can be enormous. Not just from a financial cost to repair factor but the PR damage done from failure on show site. Therefore, we buy the biggest and baddest device we need and STILL pay no more than about 2 grand per amp. These amps can also function to spec with less than ideal power and endure extreme long term handling.

I have yet to see any "audiophile grade" (mega buck) amp come close to that ability.

The Mark Levinson 532H series is in that camp from reliability point of view. That is not by accident and is due to the factors you mention. The Mark Levinson group was combined with the same group that builds the Pro products such as Crown amp. The result was that they took a lot of techniques that lead to high reliability in pro products and incorporated it there. They have sold thousands of channels of 532H and reliability data that Harman has is exceptional.

The exception is pricing. The 532H simply has a lot more in it, and is sold in much lower quantities so the MSRP reflects that. Passive cooling for example is a requirement in many home equipment but not at all in pro where noisy fans are just fine.

On pro products being called "cheap," I don't think anyone calls them that. It is just that cost competitiveness is everything in that space so you are not going to see esoteric efforts to get improved fidelity.

Note: my company sells both types. We move 10X more pro products than audiophile if not higher.
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post #92 of 2598 Old 06-14-2011, 12:30 PM
 
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Originally Posted by arnyk View Post

Sound quality also means somethng in the pro sound marketplace.

Up to a point. The key metric is not audible fidelity but specifications. Get the THD number low enough and you are golden from marketing point of view.

Quote:
Most if not all pro sound power amps would pass a straight wire bypass test when included in a very diagnostic audio chain.

That's a claim. It is not data.

Quote:
Just to drop a name, the engineering department of say, Crown.

No one in Crown division of Harman would say Mark Levinson amp designs of the same company are "lame."

Quote:
That is predictable if you have a basic understanding of the laws of economics and statistics. In general the cheap stuff sells in higher volume than the boutique brands. The relevant parameter for this discussion is percentage of failure, which you probably don't know.

If that is the relevant point, then Ethan did not know it either and hence his comment was very wrong.

For my part, I have lots more data than you or Ethan. I repaired hundreds of amps while going to college. Mass market products would often have the same part fail in the same series to the point where we would fix them in two minutes without even trying to troubleshoot them. We would put improved parts in there and they would be good to go from then on.

You are right that I don't have the stats anymore than you or Ethan do. But I have tons of hands on experience with failing cheap designs to know that the statement he made simply doesn't hold water.

Quote:
There's no evidence that inexpensive products are run closer to their limits. In fact high volume products generally receive much more intensive engineering and development per model because the costs are spread over a large number of items, and there is a larger liability when the large number are sold.

Says who? I have looked at the schematics and repaired tons of products. I know when cost cutting is in play. I have also had business relationship with ALL the major consumer electronics companies. I know that vast majority of equipment is sold at cost or below. You want to tell me they don't look for every opportunity to reduce costs, and I will tell you that you are living in dreamland. There is no more brutal market than mass market products. The successful ones are the ones that master the art of reducing the cost the most without impact "marketing numbers."

Quote:
If you someone doesn't have those statistics right there on their desk, they have no right to chastize someone else for doing exactly what they are doing - arguing without the relevant facts before them.

I have enough data to prove his generalization to be wrong. You are situated like him with no data so not sure why you are intervening.
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post #93 of 2598 Old 06-14-2011, 12:38 PM
 
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Originally Posted by amirm View Post


...so you are not going to see esoteric efforts to get improved fidelity.

I don't know about that. One sees quite a bit of esoteric efforts to get improved fidelity and ease of use in pro amps that one rarely if ever sees in audiophile amps.

Things like:

Stacked switchmode power supplies

Built in remote-programmable DSPs.

Remote monitoring

Operate on just about any legal power line voltage anyplace in the world without adjustments

Thing is, these are features whose effectiveness is actually reliably observable, as compared to the unsubstantiated claims of improved sound quality that abound in audio's high end!
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post #94 of 2598 Old 06-14-2011, 12:53 PM
 
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Originally Posted by amirm View Post

Quote:

Quote:
Originally Posted by rnyk View Post

Sound quality also means somethng in the pro sound marketplace.

Up to a point.

That point is called audibility with a good safety margin. This compares to the pointless claims typically made by the purveryers of high end boutique products.

Quote:
Originally Posted by Amir View Post

The key metric is not audible fidelity but specifications.

That's an unfounded assertion and perhaps even a bit libellous.

To make a credible claim here Amir, you would have to have done as many DBTs of pro amps as I did before I said what I said, and then have signficiantly different outcomes. I guarantee you that I've tested 5 different pro audio amps. Then there are at least 5 other consumer power amps that I've done DBTs of.

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Get the THD number low enough and you are golden from marketing point of view.

And your proof or supporting data for that demeaning claim is exactly where?

Quote:
Originally Posted by amir View Post

Quote:
Originally Posted by arny View Post

Most if not all pro sound power amps would pass a straight wire bypass test when included in a very diagnostic audio chain.

That's a claim. It is not data.

Amir, you seem to think you know all about my DBTs of pro audio amps.

OK Amir, if you know all about the DBTs involving pro amps that I have done, list at least 5 of the makes and models that I tested.
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post #95 of 2598 Old 06-14-2011, 12:57 PM
 
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Originally Posted by arnyk View Post

I don't know about that. One sees quite a bit of esoteric efforts to get improved fidelity and ease of use in pro amps that one rarely if ever sees in audiophile amps.

I was talking about audio fidelity and you broaden that to include "ease of use?" Isn't there a debating term for that?

Quote:
Things like:

Stacked switchmode power supplies

Who says switchmode power supply is in there for improved fidelity? It is there to reduce weight and size both of which reduce cost. I have yet to see an article where analog designer brags about how going from linear to switchmode power supply improved fidelity.

Quote:
Built in remote-programmable DSPs.

DSPs are convenient for the designer and installer of the system. And can be used to improve subjective fidelity. We for example use them with our in-ceiling speakers to shape their response and get the most performance out of them. So if you want to argue that modifications of signal is fair game and that the feature must be built-in, then fine.

Quote:
Remote monitoring

Mark Levinson amps have the same feature. There is an Ethernet port on the back and you can peer into the machine and see environmental and fault conditions just the same. Again, not a fidelity feature.

Quote:
Operate on just about any legal power line voltage anyplace in the world without adjustments

Home users don't relocated to foreign countries often enough for this to be a useful function. But some audiophile products are designed that way with a switch selectable power setting. Again, not a fidelity issue unless you want to argue that the equipment runs better at higher voltage as some do.

Quote:
Thing is, these are features whose effectiveness is actually reliably observable, as compared to the unsubstantiated claims of improved sound quality that abound in audio's high end!

Well, there is hardly anything you listed to back the point of superiority of pro amps from fidelity issues. If the above features were desirable in home equipment, they would exist there even easier due to lack of price pressure in high-end gear.

As to unsubstantiated claims, that is a claim by you just the same . The Mark Levinson 53 has demonstrable power advantage over many other amps. You don't need to imagine it is there. You can feel it in your behind as it powers your speakers .
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post #96 of 2598 Old 06-14-2011, 01:06 PM
 
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Originally Posted by amirm View Post


For my part, I have lots more data than you or Ethan. I repaired hundreds of amps while going to college. Mass market products would often have the same part fail in the same series to the point where we would fix them in two minutes without even trying to troubleshoot them.

Sounds like you worked in a warranty repair station. Been there, done that.

One problem with that sort of experience is that you get a distorted view of equipment reliability. You only see the dead ones and have no idea of how many lived.

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We would put improved parts in there and they would be good to go from then on.

In the days when I did that sort of thing we had to engineer the improved parts ourselves.

Amir, you seem to believe that you know my CV very well - so well that you can make arrogant claims like this about what people don't know.

I'll give you a hint - I probably know a lot more about your CV than you know about mine!

How did you know that I didn't fix audio gear professionally at some point in my somewhat longer life? You were wrong!

How do you know that I don't have access to similar information from friends who did the same?

You don't. :-(
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post #97 of 2598 Old 06-14-2011, 01:10 PM
 
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Originally Posted by arnyk View Post

That point is called audibility with a good safety margin.

Again, more claims. Show me data. You claimed they pass wire test. Where is that test data?

Quote:


That's an unfounded assertion and perhaps even a bit libellous.

It is unfounded to you, not to those of us in the industry who routinely talk to our suppliers about the equipment they offer for sale to us. You want to make up a world where pro companies do blind tests and do designs based on that for every new model, and strive for lowest level distortion, be my guest.

Quote:


To make a credible claim here Amir, you would have to have done as many DBTs of pro amps as I did before I said what I said, and then have signficiantly different outcomes. I guarantee you that I've tested 5 different pro audio amps. Then there are at least 5 other consumer power amps that I've done DBTs of.

I don't know your hearing ability or testing fixture/methodology. In absence of that, what you just said is just a a claim as I mentioned. I have conducted dozens of DBTs and none of that counts for anything in your book. In that sense, your expectation that I have to take your word for it is not logical.

This is especially so since i have independent blind testing data of amps points to most majority of them failing the so called "wire test." I have shown that to you before. That you consider your own data more valid is fine but not something I am going to rely on.

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And your proof or supporting data for that demeaning claim is exactly where?

You want me to prove this to you but I am supposed to take your word above regarding DBT? I am in the industry Arny. My company evaluates and sells both types of products. And we hear private conversations regarding positioning and design goals of products. I am not going to disclose everything I hear but have given enough data points for you to understand them. If not, fine. It is not my goal to convince you of something.

Quote:


Amir, you seem to think you know all about my DBTs of pro audio amps.

I would only know that if you disclose them. Until then, it is a claim, not data.
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post #98 of 2598 Old 06-14-2011, 05:50 PM
 
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Originally Posted by amirm View Post

Again, more claims. Show me data. You claimed they pass wire test. Where is that test data?

Take me at my word or prove that I'm lying.

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It is unfounded to you, not to those of us in the industry who routinely talk to our suppliers about the equipment they offer for sale to us.

That's not a sentence and has no discernable meaning.

Quote:


You want to make up a world where pro companies do blind tests and do designs based on that for every new model, and strive for lowest level distortion, be my guest.

What powers of mind reading do you claim when you make such statements, Amir?

Quote:


I don't know your hearing ability or testing fixture/methodology.

In case you haven't figured this out yet Amir, you are not the proctor of the world. Not only are you not free to claim that you can read my mind, but you are not free to demand anything of me.

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In absence of that, what you just said is just a a claim as I mentioned.

No Amir you are not the master of this universe and I don't have to grovel before you to make statements whose value is up to whoever reads it.

Quote:


I have conducted dozens of DBTs and none of that counts for anything in your book.

I have no knowlege of any review that I have done of those alleged events.

In fact Amir, you don't know what I think about your DBTs, since you have reported zilch about them.

Quote:


In that sense, your expectation that I have to take your word for it is not logical.

Since you made up all of he evidence that supports the above statement...

Quote:


This is especially so since i have independent blind testing data of amps points to most majority of them failing the so called "wire test."

Intersting. All this comes to light now, why?


Quote:


I have shown that to you before.

Please provide a link to where this happened in the past.

Quote:


That you consider your own data more valid is fine but not something I am going to rely on.

I don't know what you are talking about.
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post #99 of 2598 Old 06-14-2011, 06:38 PM
 
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Originally Posted by amirm View Post

I have conducted dozens of DBTs
I have independent blind testing data of amps points to most majority of them failing the so called "wire test."
I...

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post #100 of 2598 Old 06-14-2011, 07:11 PM
 
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Intersting. All this comes to light now, why?

Please provide a link to where this happened in the past.

http://www.avsforum.com/avs-vb/showt...9#post20280499

You acknowledged the above a few posts later. So I know you read it.

Just because you don't recall the conversation, it doesn't mean that it has 'come to light now.' I have referred to the above tests many times in this forum going back 2 years now. And per above, between the two of us a couple of months ago.

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I don't know what you are talking about.

That you claim to have done tests that contradicts above.
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post #101 of 2598 Old 06-14-2011, 07:11 PM
 
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People will go extra mile when money making opportunity is involved.
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post #102 of 2598 Old 06-14-2011, 07:22 PM
 
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Originally Posted by arnyk View Post

Sounds like you worked in a warranty repair station. Been there, done that.

No, I did not work in a warranty center.

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I'll give you a hint - I probably know a lot more about your CV than you know about mine!

Since you know my "CV" then this story is already known to you. But I will go ahead and tell it for the benefit of others.

When I was managing R&D at Sony, we were designing a new laptop. Needing a battery for it, we called the company that had #1 share worldwide in rechargeable batteries. Being Sony, when you call, the whole factory shows up . So there I was, with the SVP of worldwide sales and his sales engineering staff, getting ready to pitch us their batteries.

To my surprise, before he stated he asked me, "how long of a warranty will you be offering your customers?" I couldn't figure out what that had to do with us understanding what they had to offer. So I asked why he was starting with that question. His answer was that it would determine what battery we would want to use!

He said that they had three tiers of batteries:

1. One for devices like cordless home phones that had 3 months warranty and super cost driven. They used their cheapest chemistry battery for that market which would last at least 4 months to 6 months but that was it. If you ever wondered why the battery in these devices doesn't hardly last, now you know why!

2. Next step up in material and chemistry that was for products that had a year of warranty. For them, they have a batter that lasts 18 months or so. But there was a good jump in cost.

3. Finally, for devices that had longer warranty but he was definitely recommending that we don't go there due to much increased cost.

So I asked how much of this had to do with the so called "memory effect" and whether it was the poor consumer use that led to early demise. To my surprise, he said memory effect was a myth! He said they had done studies and even if you deeply charged and discharged of a NiCad battery (Lithium Ion/Polymer was not yet available then), they would last only slightly longer. He said the phenomena was directly the result of so many cheap batteries in category #1. They died because of poor and cheap construction, not because of charging behavior. Of course, who was going to try to correct the people and tell them the truth? Memory effect was a convenient excuse and they let it be.
Quote:


How do you know that I don't have access to similar information from friends who did the same?

You don't. :-(

Well, I am going to assume from now on that you also know stories like above. And that cost of a product has a direct impact in quality of parts and components used within as I explained. Now if you don't know stories like that since you have never tried to manufacture large scale hardware.....
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post #103 of 2598 Old 06-14-2011, 07:24 PM
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As someone who repaired amps for many, many moons (40+years) along with all other types of AV gear, (mix desks, distro-amps, wireless mics, video gear, thousands of miles of cabling, etc) I had a policy of bench burning every amp or active device after repair no matter what the repair was. The system had an RMS AC meter on the input, another on the output, a calibrated load (then a full range speaker) a 2 channel scope (on input and output), a THD meter, and a calibrated linear swept freq generator. I also had a variable U/D ramp generator driving a digital pot so the input level would be randomly ramped up and down for a more dynamic test. The burn-in after repair was usually about 5 hours running an average of 50-85% of the rated output level. After the swept tone sequencing, the test system automatically switched to dynamic sources. Originally, industry test cassettes and then CDs.

We used Crown, QSC, BGW, Ashley, TOA, a couple very old Phase Linears, Crest, Peavey, and a few others. The biggest difference was in the noise floor.

In all those we never had a particular brand unit fail more than another. Some were favorites for other reasons but high failure rates were not encountered by price points. Performance of all was generally quite tight to the listed and desired specs. IMO. if any amp can survive the rigors of pro use and maintain the specs which are rather exacting, i would say it would more than fill the bill for any audiophile's system using testable and repeatable real world physics and speaking in REALISTIC terms.
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post #104 of 2598 Old 06-14-2011, 07:37 PM
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Originally Posted by amirm View Post

Up to a point. The key metric is not audible fidelity but specifications. Get the THD number low enough and you are golden from marketing point of view.

From the Macro-Tech i Series page:

The Crown® Macro-Tech® i Series continues the Macro-Tech legacy of unparalleled sonic accuracy and detail, putting sound quality above all else

Still kicking myself for missing a Macro-Tech 1200 on CList for $200...

An audiophile likes to talk about how much they spent and how good it sounds.

A DIY'er likes to talk about how little they spent and how good it sounds.

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post #105 of 2598 Old 06-14-2011, 10:30 PM
 
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And that cost of a product has a direct impact in quality of parts and components used within as I explained.

Not when it comes to cables and amps for audible quality.
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post #106 of 2598 Old 06-14-2011, 10:42 PM
 
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Originally Posted by diomania View Post

Not when it comes to cables and amps for audible quality.

More claims absent of data.
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post #107 of 2598 Old 06-15-2011, 04:35 AM
 
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Originally Posted by amirm View Post

I have conducted dozens of DBTs
I have independent blind testing data of amps points to most majority of them failing the so called "wire test."
I...

. . . . . . . . . . .
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More claims absent of data.




cheers,

AJ

p.s. I wonder how long Dunny is going to take this??
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post #108 of 2598 Old 06-15-2011, 05:52 AM
 
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Originally Posted by amirm View Post

http://www.avsforum.com/avs-vb/showt...9#post20280499

You acknowledged the above a few posts later. So I know you read it.

Sorry Amir. You know that I can't read that thread, and you know why and are probably responsible for it. I'm not accepting a pig in a poke.
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post #109 of 2598 Old 06-15-2011, 05:53 AM
 
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Originally Posted by diomania View Post

Not when it comes to cables and amps for audible quality.

Not in gereral when it comes to high end audio.
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post #110 of 2598 Old 06-15-2011, 08:02 AM
 
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More claims absent of data.

This just proves that you've never looked at the interior of Levinson amp carefully. How can you be a seller of Levinson amp and not know what's in it?

A lot of money went into the cosmetics, not audible quality to those who trust their ears only.
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post #111 of 2598 Old 06-15-2011, 09:59 AM
 
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Originally Posted by arnyk View Post

Sorry Amir. You know that I can't read that thread, and you know why and are probably responsible for it. I'm not accepting a pig in a poke.

I am not responsible for anything. I don't have any moderator powers on this forum and have never complained about you or another poster arguing with me. If you can't read that thread, it is your doing and forum management decision. So if anyone is "probably responsible" is yourself and your actions.

Anyway, here is the thread again:

-----------------------------------------------------------------
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Originally Posted by arnyk View Post

The parallel truism is that all good amplifiers sound the same, and the definition of a good amplifier is that a good amplifier sounds the same as all the other good amplifiers.

And you have an exhaustive blind study to show that? 'cause I do have a good one for the opposite .

I suspect you don't know Ing. Öhman although you should. OK, so most people here probably never heard of the man if they don't live in Europe. Ing runs the Audio Engineering Society type of group in Sweden and is a speaker designer and magazine review amongst other things.

Ing is an extreme advocate of blind testing and does all of his magazine reviews that way. His web site is full of articles on the necessity of removing listener bias. His writing is in Swedish which is very worthwhile to search and read using a translation engine. Fortunately there is one article that is translated by Bryston into English for reasons which will become clear in a moment.

What he has done is that he has built a simulated load for a speaker including its cross-over and such. Others have done the same. But he goes one step further: he has built a divider in there, letting him back out all of the amplifier gain. In other words, he brings the level back down as if the amp was never there. But of course, it is still there, doing its thing as it always has. He just throws out most of its output and preserves a small sampling for taste.

Ing then takes that much reduced output, and feeds it to a selector switch together with the original source. He then amplifies that normally as if they were two normal sources. They then perform both blind and non-blind listening tests to see what coloration the amp may be adding. If an amp is like a piece of wire, then it would sound identical to its input. Otherwise, you will hear a difference. He calls this the Bypass Test. As you see below, they find such coloration in every amp they have tested, sans this one Byrston: http://bryston.com/pdfs/07/Swedish14BSSTReview.pdf

Here are some key quotes:

"The outcome of the second Bypass Test became different from ever before. To explain how, I have to start with explaining the normal procedure, and results: A normal Bypass-listening test typically involves 3 to 6 listeners, listening to the two alternative signals, B (Before = bypassed) and A (After = the test object is inserted into the signal path).

This is first done openly, i.e. all listeners knows which is B (before object) and A (after object), and that open listening is often done for a longer period of time. During this listening, people are allowed to talk to each other about what they hear or think they hear. Thus, it's possible to learn from each other, and vague characteristics that take a long time to identify for one listener, typically get identified very fast, due to the cross communication of experiences.

When the blind verifying listening thereafter takes place, it is still an option to talk to the other listeners, but of course it is difficult to draw any conclusions since it is no longer known which one is B or A. To sum it up, normally there are lots of views, ideas and opinions regarding the character of the tested amplifier after the open listening. That was not the case this time.

We were sitting in open listening for well over one hour, and no one mentioned a single word about any differences they either imagined or heard. Actually, that's the first time ever something like that has happened. ...This is the first time that none of the listeners even believed that there was any audible difference what so ever between input and output of the amplifier."

Your turn.
-------------------------------------------------------

And your response to it after quoting part of above:

Quote:
Originally Posted by arnyk View Post

I see no innovation here. I've been building amplifier loads, both resisitve and reactive, with voltage dividers in them for the purpose of creating a net gain of 1.0 for for at least 15 years. When I built my first one I has zero sense of being an innovator. It was an obvious outgrowth of prior art.

If memory serves David Hafler published a schematic for a device for doing straight wire bypass testing in the mid-80s, I seem to recall Reginald Williamson doing something similar back in the 60s.

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post #112 of 2598 Old 06-15-2011, 10:09 AM
 
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Originally Posted by diomania View Post

This just proves that you've never looked at the interior of Levinson amp carefully. How can you be a seller of Levinson amp and not know what's in it?

A lot of money went into the cosmetics, not audible quality to those who trust their ears only.

Posting pictures is not "data." You keep making claims with no foundation to prove any of them.

Let me show you "data." This is the response of NAD M2 switching amplifier frequency response:



This is the Mark Levinson No 53 switching amplifier response:



This is *data*. A random guy on the Internet whose alias ends in "mania" claiming he knows all the improvements in Mark Levinson are cosmetic with no fidelity differences, has negative value to forum readers in the way it wastes their time and adds nothing to the conversation.

My company sells Crown amplifiers and we make excellent money doing that too. So if you all are convinced that the Crown pro amps are the way to go, nothing would please me more. So it is not like I don't like the direction you are going. I just like to tell it like it is. The Crown amps very well designed and are actually powering one of our theater systems. I just wouldn't elevate it to the level of Mark Levinson 53 above for pure music listening. They share class I technology but there are lots of improvements there as evidenced in the above graphs. Getting the effective switching frequency up in Mhz region is not cheap or free or every other class D amp would be doing it.
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post #113 of 2598 Old 06-15-2011, 10:20 AM
 
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Oops. The review site for the Mark Levinson just went down. What are the chances for that? . Can't get Google cached version to get accepted here either. Let's see if it comes back up or I find another way to get a copy of the graph.
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post #114 of 2598 Old 06-15-2011, 10:35 AM
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Quote:
Originally Posted by amirm View Post

This is first done openly, i.e. all listeners knows which is B (before object) and A (after object), and that open listening is often done for a longer period of time. During this listening, people are allowed to talk to each other about what they hear or think they hear. Thus, it's possible to learn from each other, and vague characteristics that take a long time to identify for one listener, typically get identified very fast, due to the cross communication of experiences.

.[/b]"

Your turn.
-------------------------------------------------------

And your response to it after quoting part of above:

Doesn't this also open up for a bias to be "passed on" so to speak. Generally, I find people want to be part of group and to say you don't hear something others do would seem to me to be a pressure in of itself.
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post #115 of 2598 Old 06-15-2011, 10:42 AM
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^^^

yes, amoungst a bunch of other issues with that...

- chris

 

my build thread - updated 8-20-12 - new seating installed and projector isolation solution

 

http://www.avsforum.com/t/1332917/ccotenj-finally-gets-a-projector

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post #116 of 2598 Old 06-15-2011, 10:45 AM
 
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Quote:
Originally Posted by AJinFLA View Post

. . . . . . . . . . .


If I didn't think posting animated GIFs in this forum would not be a sign of low class, I would have used the very ones you used to respond to you . You were very active in the thread I linked to above so whatever excuse you have for thinking no link was provided was just that, an excuse.

Realizing that you don't believe in blind testing of your speakers and hence this may fall on deaf ears, here are more links for you: http://173.203.156.112/Uploads/Files...3_Brochure.pdf

"New Mark Levinson products are not introduced with the seasons, or according to arbitrary marketing schedules. They're introduced as new technologies, which have shown promise on paper, are perfected and proven through rigorous in-house development and evaluation procedures. In the case of the No53, a highly experienced evaluation team was assembled to conduct blind and sighted listening tests of a novel switching amplifier prototype, measuring it against past and present Mark Levinson linear power amplifiers as well as a range of competitive products.

As the development process wore on, power amplifiers deemed sonically inferior were removed from further testing. Several judges were surprised to learn that the new switching amplifier was never among them. In fact, the early No53 prototype emerged as a winner, with several panelists awarding it top honors for speed, dynamics and clarity. It was, to say the least, an
unexpected result. For a mere prototype switching amplifier to hold its own against linear amplifiers that were deemed to be the very best the marketplace had to offer - time-honored Mark Levinson models included - meant we knew we were dealing with a paradigm-shifting design.

With the technical hurdles of switching power amplifiers behind us and with the internal layout finalized, the No53 development team headed back to the listening room. We listened with different types of music. We listened with different speakers, electronics and cables. We listened in different rooms. We compared the No53 to other Mark Levinson power amplifiers. We compared it to the power amplifiers of our competitors. We listened blind, we listened sighted and we flew in customers from around the world to listen with us. Only then, when we were convinced that we had coaxed the last ounce of performance from this revolutionary design, did the No53 go into production."

http://173.203.156.112/Uploads/Files...10_5.17.10.pdf

"Listen Testing & Evaluation
At each stage of the №53's development, extensive listen testing and thorough measurements ensured that our goal of Mark Levinson Reference Class performance was attained. In addition to multiple rounds of in-depth critical listen-testing over a period spanning many, many months, a differential amplifier comparison methodology was also employed. A low power, mostly passive reference amplifier design was programmed with the №53's transfer function, and differentially (subtractively) compared against the №53 itself. By subtracting the signal output from the №53, and comparing against the reference transfer function design, our engineers were able listen to any differential components between the two, and evolve the №53's design to improve sound quality even further."

Do you have data like this from the company that built the amp you bought AJ? How about any other pro amp company?
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post #117 of 2598 Old 06-15-2011, 10:48 AM
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Amirm, ing's test methodology is flawed. Sorry. No one rational is claiming all amp MEASURE the same. Nor do we claim they measure the same as a piece of wire. All his 'bypass' test proves is the above.


We have a threshold for audibility of distortion. He is comparing two signals of varying levels of distortion, one above our threshold and the other below. Or if using a poor amp for his test, bad and worse audible distortion.

Is it any wonder that at a minimum doubling the distortion in one signal might raise it above our threshold and thus become audibly distinguishable fro another signal? What is a wonder is that you believe this methodology is in any way revealing of the audible differences in amplifiers used under normal circumstances. ie, with signal passing through only once.

It's like saying cables DO sound different because they CAN sound different. Similarly, proving that amps CAN sound different (what he has done) has zero relevance on the question of whether good ones DO.

Next reference.

Better yet, where are the results of these rigorous dbt's you have conducted? I'd love to see those results and methodology.

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Quote:
Originally Posted by amirm View Post

but there are lots of improvements there as evidenced in the above graphs.

What kind of improvement, audible one? Posting those two graphs is not a proof of audible comparison, not to mention the different conditions those two graphs represent. How about actual listening test of those two amps where the listeners used their ears only?

You still don't know what's inside of Levinson amps you sell, do you?
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post #119 of 2598 Old 06-15-2011, 11:00 AM
 
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Quote:
Originally Posted by Randy Bessinger View Post

Doesn't this also open up for a bias to be "passed on" so to speak. Generally, I find people want to be part of group and to say you don't hear something others do would seem to me to be a pressure in of itself.

Correct. Group testing is not a good idea. It creates a herd mentality. Your observation is excellent in this respect .

That said, all tests are imperfect. Question is, can we still glean some useful information from them. If our standard for blind testing is perfection, then I say we have zero data to go on.

Just think of the nature of inserting a switch in the output of anything. An audiophile who believes in fancy cables and such would immediately call foul. Folks would of course tell them he is an idiot and the switch doesn't do anything to the test. So using the same logic, I would say that we don't know that the herd mentality caused all but one test to go the other way especially when the author worships unbiased and blind testing and has a web site dedicated to the cause.

And given an experiment we can evaluate vs a secret one by Arny and the statement "trust me" I will put my money 100% on the former every day of the week and twice on Sunday. If we had Arny's protocol, who is to say we would not find more flaws with it?

So sure, this is another piece of imperfect data as we try to sort out way through this complex area. Ultimately, I am not here to tell you amps or interconnects color sound. You need to run your own tests to know for sure. I have done that and the stance I have on speaker cables is that I have never tested them so don't know one way or the other. On Interconnects, I have measured them as I post earlier showing there is no difference objectively. I have blind tested myself though and found small difference.

I have not blind tested amplifiers. I have however found them in bass performance to be differentiated in amount of power they convey. This is not an audiophile observation. I am not talking about vague things you can't decisively feel. I find that all the switching amps I have tested including the pro unit from Crown, sans the Mark Levinson 53 to have less clean highs. This is a subjective experience and am happy to be told is wrong . But it is my observation and I use it to make my equipment choices. You are welcome to do otherwise.
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post #120 of 2598 Old 06-15-2011, 11:02 AM
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Quote:
Originally Posted by amirm View Post

Do you have data like this

That's just marketing material from the manufacturer, and in no way constitutes any sort of data for any audible difference for that amp over any other competently designed unit.
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