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Sound quality of amplifiers
Agitator
post Mar 24 2013, 17:43
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Hi.

Is the following statement true or false:

Any transistor-based amplifier with enough power to drive a specific pair of loudspeakers will sound exactly the same as any other transistor-based amplifier with enough power to drive the same pair of loudspeakers. (Sorry about the long sentence).

If the statement is true: does anyone have any links to ABX-tests of amplifiers?


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Soap
post Mar 24 2013, 18:00
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It's clearly false. All sorts of bad decisions can be made in amplifier design and construction.

But it's also clearly false simply because it's a silly question. For if I tell you "Yes, that statement is true." (because it should be true given reasonable assumptions) someone could quickly find some PoS transistor amp which is the exception. The world's a large place - there's plenty of crap in it.


A more useful question would be: "Is any competently designed and implemented amplifier using long-known best practices and relying only on commodity parts of rather pedestrian and non-exotic sourcing with enough power..."

This post has been edited by Soap: Mar 24 2013, 18:02


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Agitator
post Mar 24 2013, 18:19
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You're right. So, what would the answer to your question be? Are most "decent" amplifiers transparent?

Or am I wrong in assuming that $3,000 amplifiers are snake oil?


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julf
post Mar 24 2013, 20:56
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QUOTE (Agitator @ Mar 24 2013, 18:19) *
You're right. So, what would the answer to your question be? Are most "decent" amplifiers transparent?


Yes. Or at least much more transparent than your speakers, room and ears. smile.gif

QUOTE
Or am I wrong in assuming that $3,000 amplifiers are snake oil?


Yes and no. Are diamond-studded wheels on a Bentley snake oil?
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db1989
post Mar 24 2013, 20:57
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Yes, in that they’re based upon an appeal to emotion and/or bragging rights, rather than any actual benefit to functionality.
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Agitator
post Mar 24 2013, 23:30
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Thanks.

Now to something related: amplifiers for electrostatic speakers differ from amplifiers for dynamic speakers. Something to do with the impedance etc.

I guess there's a lot of snake oil among that sort of amplifiers as well, but is the starting price of transparent amplifiers for electrostatic speakers the same or higher?

A guy I know went into a hifi shop and tested a pair of MartinLogan speakers. The salesman talked about a $17,000 amplifier (Mark Levinson) that he would not recommend, because he would rather sell a $3,500 amp that was just as good as the Mark Levinson for the MartinLogans.

In my opinion, that was just a trick to get his trust (as most customers would not afford a $17,000 amp).

It should be possible to find a transparent amp for less than $1,700, and preferably less than that, shouldn't it?

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saratoga
post Mar 24 2013, 23:40
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QUOTE (Agitator @ Mar 24 2013, 17:30) *
Now to something related: amplifiers for electrostatic speakers differ from amplifiers for dynamic speakers. Something to do with the impedance etc.


Yes, they run at very high voltage, so you either need a transformer to step up the voltage of a more conventional amp, or an exotic type of amplifier that can operate at very high voltages directly.

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Ferongr
post Mar 25 2013, 00:59
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The statement is probably incorrect (assuming "amplifier means an integrated amplifier or multichannel receiver) because an "amplifier" has many sections that cost-cutting may affect. I have a Marantz SR4300 near me that has audible flaws like audible hiss on both channels and mains buzz on the right channel (I don't think I break TOS8 for such audible flaws, right?). The hiss comes from the A/D converters fed from the analog RCA inputs (SP/DIF inputs have no hiss) and is constant for 2/3rds of the volume control range, over which point it gets amplified exponentially. The buzz is constant regardless of volume setting and is present even before the speaker relays close, the few seconds after turning the amplifier.

Purchasing something blindly without either an audition or a review backed by measurements is inadvisable anyway.

This post has been edited by Ferongr: Mar 25 2013, 01:00
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mzil
post Mar 25 2013, 05:25
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QUOTE (Agitator @ Mar 24 2013, 17:30) *
Now to something related: amplifiers for electrostatic speakers differ from amplifiers for dynamic speakers. Something to do with the impedance etc....
A guy I know went into a hifi shop and tested a pair of MartinLogan speakers. The salesman talked about a $17,000 amplifier (Mark Levinson) that he would not recommend, because he would rather sell a $3,500 amp that was just as good as the Mark Levinson for the MartinLogans.

In my opinion, that was just a trick to get his trust (as most customers would not afford a $17,000 amp)...

There's no need for an exotic amp. Depending on the situation, one could even use just a good quality receiver alone (without any additional outboard amp) with, say, 100 to 200 watts/ch., which is what most MartinLogan owners actually use. Ideally the receiver should be able to comfortably power a 4 ohm load, which most of them can, even if they aren't officially rated as such. [Independent magazine reviews, such as Home Theater, do 4 ohm tests on receivers, one can check out for this info.]

I agree your suspicion regarding his tactic of "just to gain his trust" was a trick.

P.S. Electrostatic speakers of the past and/or other brands may be a different animal. Also most if not all current MartinLogans aren't even full range electrostatic panels, they are "hybrids". The power hungry bass is handled by a built-in amp which drives conventional cone woofer(s) in a sealed cabinet, underneath the electrostatic panel part which handles only the mid and upper frequencies.

This post has been edited by mzil: Mar 25 2013, 05:43
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dhromed
post Mar 25 2013, 11:10
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QUOTE (Agitator @ Mar 24 2013, 18:19) *
Or am I wrong in assuming that $3,000 amplifiers are snake oil?


Amplifiers needn't go beyond $500, as far as I'm concerned.
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Arnold B. Kruege...
post Mar 25 2013, 13:07
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QUOTE (Agitator @ Mar 24 2013, 13:19) *
You're right. So, what would the answer to your question be? Are most "decent" amplifiers transparent?

Or am I wrong in assuming that $3,000 amplifiers are snake oil?



There are several ways to build a $3000 amp that are not snake oil, such as one with exceptionally high power (killowatts), or many channels, or perhaps suiting some very special purpose.

However, > 20 wpc amps that are sonically transparent can and are be built and sold for $1 a watt or less. The low water mark for power comes from the fact that there is some cost overhead involved with building a case and a power supply.

The most common unusual audible property of very expensive power amplifiers is that they provide a relatively high source impedance. This can be effectively simulated in many cases by placing a 0.5-3 ohm power resistor in series with each positive speaker lead attached to the amp.

In general an effective methodology for obtaining a number of reasonably powered full featured power amplifiers is to obtain an AVR or receiver for use in an audio/video system.

This post has been edited by Arnold B. Krueger: Mar 25 2013, 13:09
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Arnold B. Kruege...
post Mar 25 2013, 13:09
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QUOTE (dhromed @ Mar 25 2013, 06:10) *
QUOTE (Agitator @ Mar 24 2013, 18:19) *
Or am I wrong in assuming that $3,000 amplifiers are snake oil?


Amplifiers needn't go beyond $500, as far as I'm concerned.


IME that's about $300 or more too high int his day and age.
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Arnold B. Kruege...
post Mar 25 2013, 13:22
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QUOTE (Ferongr @ Mar 24 2013, 19:59) *
The statement is probably incorrect (assuming "amplifier means an integrated amplifier or multichannel receiver) because an "amplifier" has many sections that cost-cutting may affect. I have a Marantz SR4300 near me that has audible flaws like audible hiss on both channels and mains buzz on the right channel (I don't think I break TOS8 for such audible flaws, right?). The hiss comes from the A/D converters fed from the analog RCA inputs (SP/DIF inputs have no hiss) and is constant for 2/3rds of the volume control range, over which point it gets amplified exponentially. The buzz is constant regardless of volume setting and is present even before the speaker relays close, the few seconds after turning the amplifier.


If the noise is still present and audible with typical speakers in a typical room at a typical listening distance, with all sources disconnected from the inputs and the input jacks properly terminated then this is IME an unusual circumstance.

I have a far less expensive AVR namely a Yamaha RXV-371 (actually cost me < $120 as an "open box" <actually no box> but new item with full warranty) that is lacking in such flaws. Methinks you may have paid too much! ;-)

QUOTE
Purchasing something blindly without either an audition or a review backed by measurements is inadvisable anyway.


A flaw such as you have described should be noticeable in a thorough in-store audition, which begs the question of why you bought this particular receiver if you were following your own advice?

I am unaware of any published measurements that would demonstrate the flaw that you are regrettabily suffering from. It is true that the ADCs in AVRs are often lower spec than the DACs. The usual architecture of a modern AVR involves the use of an analog electronic volume control chip with high enough quality that the output of the AVR is subjectively noise free at low volumes.

You may have a product sample that is defective, which of course can always happen even to the best products.

This post has been edited by Arnold B. Krueger: Mar 25 2013, 13:23
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knutinh
post Mar 25 2013, 14:11
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So what is the rich Audiophile to do? The naysayers at hydrogenaudio claims that a $100 CD-player is transparent, that cables does not matter, that a $200 amplifier is sufficient. Is he going to push all of his cash into loudspeakers? Room rebuild? CDs? Concert tickets??

-k
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benski
post Mar 25 2013, 14:34
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Your Yamaha is rated 80W at an incredibly high 0.9% THD for stereo output. I would not consider this a quality amplifier.
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DonP
post Mar 25 2013, 14:46
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QUOTE (Ferongr @ Mar 24 2013, 18:59) *
I have a Marantz SR4300 near me that has audible flaws like audible hiss on both channels and mains buzz on the right channel (I don't think I break TOS8 for such audible flaws, right?). The hiss comes from the A/D converters fed from the analog RCA inputs (SP/DIF inputs have no hiss) and is constant for 2/3rds of the volume control range, over which point it gets amplified exponentially. The buzz is constant regardless of volume setting and is present even before the speaker relays close, the few seconds after turning the amplifier.


Sounds like a good candidate for a warranty claim. BTW, I've had a similar vintage, cheaper model, Marantz with no such problem.

Another brand preamp that had a hissy headphone output was repaired under warranty with no question. In this case the company sent the needed parts to the local dealer so I was only without it for a day or so.

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Arnold B. Kruege...
post Mar 25 2013, 15:06
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QUOTE (benski @ Mar 25 2013, 09:34) *
Your Yamaha is rated 80W at an incredibly high 0.9% THD for stereo output. I would not consider this a quality amplifier.


The myth that you appear responding to is that specs actually mean something about actual use.

A quick primer on modern amps and specs:

(1) A modern SS amp that is credibly designed usually has something under 0.02% THD under typical operating conditions.

(2) Advertised amplifier specs usually involve pushing the amp into clipping in order to have more impressive numbers for power.

I know of at least one case where an amp is rated for X output at 10% THD, but in fact has less than 0.001% THD in typical use which is actually about just about any power level and audio frequency below clipping.

There are actually far more extensive specs for the RXV-371 amps if you read here:

http://usa.yamaha.com/products/audio-visua...__u/?mode=model

"RX-V371 Owner's Manual [English]"

page 69

A more reliable guide of this amp's performance might be discerned from the spec sheet for the power amp chips that it uses:

STK433-330F-E

http://www.sanyosemi.com/en/ds_e/ENA2107.pdf

Please see "THD-PO" on page labelled "Characteristic of Evaluation Board"

Those numbers are still more like worst case specs, and less representative of typical performance.

The graph labelled "Po-F" on the same page shows how the same amp can be rated at 155 wpc or 120 wpc by simply picking a different target amount of THD.



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Arnold B. Kruege...
post Mar 25 2013, 15:11
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QUOTE (knutinh @ Mar 25 2013, 09:11) *
So what is the rich Audiophile to do? The naysayers at hydrogenaudio claims that a $100 CD-player is transparent, that cables does not matter, that a $200 amplifier is sufficient. Is he going to push all of his cash into loudspeakers? Room rebuild? CDs? Concert tickets??


Spending a high proportion of the system's budget on loudspeakers and paying lots of attention to speaker placement and room acoustics is well known in many circles to be the most cost-effective (IOW sensible) route to good sound.

What's the alternative - spending megabucks on electronics and playing it through bad speakers in a wretched room? Is that smart? ;-)

Spending money on concert tickets (or slumming at free concerts) is a good idea. These days I run into a lot of people who seem to have no idea what live music of the kind they prefer to listen to recordings of sounds like.
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Agitator
post Mar 25 2013, 15:27
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What is the bullshit factor of this article? http://www.gcaudio.com/resources/howtos/spkramp.html


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Arnold B. Kruege...
post Mar 25 2013, 15:56
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QUOTE (Agitator @ Mar 25 2013, 10:27) *
What is the bullshit factor of this article? http://www.gcaudio.com/resources/howtos/spkramp.html



IMO, Pretty high:

"Let’s say that you had chosen a loudspeaker that has a tendency toward brightness. You found that, once you got it home, your very live room exacerbated this bright character. The choice you make in mating an amplifier to your speakers will have a significant impact on whether you further aggravate or help to downplay the tonal imbalance you perceive. To best determine a match, it's important to work with a dealer that can give you a detailed description of the tonal character of the various components that fit your budget and preferably one that will let you audition the amp with your system . Ultimately, the only way to be absolutely certain of the ability of an amplifier to mate with a given speaker, is to try it."

A good amp is supposed to and generally does work well with any reasonable loudspeaker.

This post has been edited by Arnold B. Krueger: Mar 25 2013, 15:57
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Arnold B. Kruege...
post Mar 25 2013, 16:39
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QUOTE (Agitator @ Mar 24 2013, 12:43) *
Hi.

Is the following statement true or false:

Any transistor-based amplifier with enough power to drive a specific pair of loudspeakers will sound exactly the same as any other transistor-based amplifier with enough power to drive the same pair of loudspeakers. (Sorry about the long sentence).

If the statement is true: does anyone have any links to ABX-tests of amplifiers?



The classic set of ABX tests of a very wide range of amplifiers.

http://home.provide.net/~djcarlst/abx_pwr.htm

A list of many ABX tests and other DBts including amplifiers

http://www.head-fi.org/t/486598/testing-au...laims-and-myths

The classic stereo review amplifier abx article

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

This post has been edited by Arnold B. Krueger: Mar 25 2013, 17:08
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pdq
post Mar 25 2013, 16:58
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QUOTE (Ferongr @ Mar 24 2013, 19:59) *
The buzz is constant regardless of volume setting and is present even before the speaker relays close, the few seconds after turning the amplifier.

So the buzz is present even before the amplifier connects to it. What does this tell you?
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Arnold B. Kruege...
post Mar 25 2013, 17:01
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QUOTE (pdq @ Mar 25 2013, 11:58) *
QUOTE (Ferongr @ Mar 24 2013, 19:59) *
The buzz is constant regardless of volume setting and is present even before the speaker relays close, the few seconds after turning the amplifier.

So the buzz is present even before the amplifier connects to it. What does this tell you?


Acoustical noise from the amplifier itself. Something is mechanically loose!
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Ferongr
post Mar 26 2013, 08:30
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QUOTE (Arnold B. Krueger @ Mar 25 2013, 14:22) *
If the noise is still present and audible with typical speakers in a typical room at a typical listening distance, with all sources disconnected from the inputs and the input jacks properly terminated then this is IME an unusual circumstance.

I have a far less expensive AVR namely a Yamaha RXV-371 (actually cost me < $120 as an "open box" <actually no box> but new item with full warranty) that is lacking in such flaws. Methinks you may have paid too much! ;-)

A flaw such as you have described should be noticeable in a thorough in-store audition, which begs the question of why you bought this particular receiver if you were following your own advice?

I am unaware of any published measurements that would demonstrate the flaw that you are regrettabily suffering from. It is true that the ADCs in AVRs are often lower spec than the DACs. The usual architecture of a modern AVR involves the use of an analog electronic volume control chip with high enough quality that the output of the AVR is subjectively noise free at low volumes.

You may have a product sample that is defective, which of course can always happen even to the best products.


I was given this old baby for free, I never paid for it. And yes, the problem appears with inputs disconnected, driving 2 relatively insensitive 87dB/W/m speakers 1.5m away from me. I did audition a different sample of the same amplifier and it exhibited the same flaws so it's not a defective unit. The volume control on the SR4300 opearates on the digital stage of the signal path.

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Arnold B. Kruege...
post Mar 26 2013, 12:37
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QUOTE (Ferongr @ Mar 26 2013, 03:30) *
The volume control on the SR4300 opearates on the digital stage of the signal path.


Just FYI, regrettably that is not the case. I obtained the service manual for a Marantz SR4300 and examined its block diagram and schematic. As is common for modern AVRs the volume control operates in the analog domain, and is implemented (in this case) via a M61516FP analog signal switch and electronic volume control chip. I suspect that the SR 4300 has a feature for bypassing the digital domain, which justified this approach.

The payback to the AVR vendors for providing this analog bypass feature is that it facilitates the sales of very expensive digital players with exotic converters and built-in decoders and bass management facilities that duplicate eminently functional features already present in the AVR. Ironically, the analog paths in these AVRs are frequently only about 16 bit CD quality so the only quality advantage existing is in the purchaser's mind. I consider it a tax on people who are prejudiced against digital and lack the intellectual resources to understand what's going on. ;-)

You can find the data sheet for this chip at http://documentation.renesas.com/doc/produ..._m61516fpds.pdf along with an explanation of who the producer, namely Renesas Technology Corporation actually is. This chip's performance in is the 100 dB dynamic range and 0.005% THD range so it should not be the cause of the audible artifacts that you have unfortunately encountered.

If you wish to check out my conclusions, I obtained theMarantz-SR4300 receiver service manual for free from http://www.eserviceinfo.com/

This post has been edited by Arnold B. Krueger: Mar 26 2013, 12:39
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