Blind Testing Amps

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
Looks like ASR did test a 2ch ATI NC52x series
Absolutely nothing to suggest a non transparent amp.
Another likely N rays scenario.
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
I think that is really the point behind amps... they should be transparent... or neutral... not adding or taking away from the sound.
 

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
Correct. Only if overdriven, malfunctioning/broken, etc., otherwise undetectable..blind :)
 

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
We know, but its published for peer review results of blind test, preferably double, using methods
That sort of bias/belief preconditioning explains your sighted A/B test results perfectly. You got the results you wanted. Hence an AVA box would throw a wrench into that. Thanks for explaining.

cheers

That is weird because I learned about the Pioneer SC-7 issue driving 4 Ohms 2 years after it was sold. In your world, observation backed by measurements discovered 2 years later are clear evidence of time-travel related bias. :)

I understand the usefulness of ABX and the blind tests performed by Harman.
They did not prove their speakers are better, they ran enough tests to provide a statistical significant design goals for flat response and dispersion that correlated with preferred sound. This was single speaker testing which was also tested and again found to correlation to stereo listening and held true for their "typical" in home room settings.

Harman presents their finding not as a proof that they have the best speakers but that they have design goals for what they have evidence is preferred.
Manufactures have very different views on what makes a good speaker. Some choose greater directivity for better HT and to combat room modes.

A balanced view, would be that nothing was proved by me, nothing was proved my @Sonnie.
@Sonnie's feels he has sufficient evidence to make good decisions for him, his room, his speakers.
His listening sessions were done with a great deal of effort and it should be applauded.

Amps should be level matched using 0 dBFS signals and an accurate sine-wave meter or equivalent. Volume attenuation must be linear and accurate for all volumes. DSPs are the best choice, especially when the source is digital. Switching should be straight wire make-and-break, straight wire. No additional components should be inserted between the amp and speakers.
If there are rational objections to these parameters I have not heard them.

I understand that my session could be improved to remove bias. No argument.
However, the connection method employed was is technically superior and components measured.

People should innovate and find ways to compare products and it is fine report what was done and their listening impressions. This should not be confused with AES white-papers.

The height of hypocrisy is proclaiming ABX tool that that provides at best .1 dB attenuation steps is wonderful. Then, acting as if the concept of .1 dB level matching is some unproven myth. If you believe that throw your AVA ABX device in trash.
If .1 dB incorrect ask Frank, why he chose it.

- Rich
 

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
That is weird because I learned about the Pioneer SC-7 issue driving 4 Ohms 2 years after it was sold. In your world, observation backed by measurements discovered 2 years later are clear evidence of time-travel related bias. :)
In my world anything before your sighted AB test in 2020-21, like Genes 2008 SC07 review, is a source of bias.
Priori knowledge.

I understand the usefulness of ABX and the blind tests performed by Harman.
Actually you don't, because they use single or multiple comparisons, ABX and ABC (anchor).
They are in no way trying to establish whether there are difference or not between loudspeakers (there is!!), but correlating measurements to preferences.
An ABX of your 2 amps, should be a difference, or really no difference test.

A balanced view, would be that nothing was proved by me, nothing was proved my @Sonnie.
@Sonnie'
Actually a technically literate view would be that your test was sighted non-randomized/highly problematic AB switching, unmatched with some kind of non-constant voltage issue, possibly caused by a lack of isolation between DUTs, etc, etc, etc. vs Sonnies designed by a knowledgeable, technically literate EE AVA ABX box, made very specifically for these exact kind of tests so that all the confounders included in yours weren't missed. The completely false equivalence is noted.

I understand that my session could be improved to remove bias. No argument.
However, the connection method employed was is technically superior and components measured.
I sometimes forget you're the veteran EE/perceptual tester and not a software guy. Forgiveness please. ;)

The height of hypocrisy is proclaiming ABX tool that that provides at best .1 dB attenuation steps is wonderful. Then, acting as if the concept of .1 dB level matching is some unproven myth. If you believe that throw your AVA ABX device in trash.
If .1 dB incorrect ask Frank, why he chose it.
0.1db is below your or any other human to detect an amp driving speakers, so well chosen. Btw, Frank didn't design these.
And I think by now we all know why you can't cite the 0.1db reference/paper/etc you claim. :)
Reality is its higher, especially for music w amp>speakers/room.
41730


https://www.sciencedirect.com/topics/engineering/just-noticeable-difference
 
Last edited:

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX

henryeng

Member
Joined
Apr 26, 2021
Messages
41
More  
Main Amp
McIntosh MA8900
Universal / Blu-ray / CD Player
McIntosh MCD550
Front Speakers
Goldenear Triton One.R
Let me know if you want to borrow the ABX box... it really is enlightening. Joe, Leonard, Wayne and Dennis all have superb ears, exceedingly better than mine, and none of us could consistently identify any differences in the following amps over several days of testing back in 2015. When we listened and knew what we were listening to, we made notes on what differences we thought we heard, but when we used the box and didn't know the two amps we were switching between, no one could match up their same comments with any consistency... bottom line, we could not prove anyone could really hear any differences.
  • Behringer EP2500
  • Denon X5200 AVR
  • Emotiva XPA-2
  • Exposure 2010S
  • Krell Duo 175
  • Mark Levinson 532H
  • Parasound HALO A31 (Sonnie's Main Amp)
  • Pass Labs X250.5
  • Sunfire TGA-7401
  • Van Alstine Fet Valve 400R
  • Wyred 4 Sound ST-500 MK II
 

henryeng

Member
Joined
Apr 26, 2021
Messages
41
More  
Main Amp
McIntosh MA8900
Universal / Blu-ray / CD Player
McIntosh MCD550
Front Speakers
Goldenear Triton One.R
Hi Sonnie,

I'd like to toss in my 2-cents-worth regarding the very insightful comments you made about evaluating amps and other gear by doing "blind A/B" testing. In a nutshell, you reported that in many cases, you and others really couldn't tell the difference between A and B if you didn't already know which you were listening to.

I'm sending you a write-up about a similar experience that I (and about 50 other audio professionals) had several years ago. It corroborates your experience. Please see the pdf attached, and feel free to post it if you think others would appreciate the story!

(OOPS! I'm a new member. The site wouldn't allow me to attach the pdf. If you'd like to see it, send me an email and I'll send it direct to your email address.)
 

henryeng

Member
Joined
Apr 26, 2021
Messages
41
More  
Main Amp
McIntosh MA8900
Universal / Blu-ray / CD Player
McIntosh MCD550
Front Speakers
Goldenear Triton One.R
Hi Sonnie,

I'd like to toss in my 2-cents-worth regarding the very insightful comments you made about evaluating amps and other gear by doing "blind A/B" testing. In a nutshell, you reported that in many cases, you and others really couldn't tell the difference between A and B if you didn't already know which you were listening to.

I'm sending you a write-up about a similar experience that I (and about 50 other audio professionals) had several years ago. It corroborates your experience. Please see the pdf attached, and feel free to post it if you think others would appreciate the story!

(OOPS! I'm a new member. The site wouldn't allow me to attach the pdf. If you'd like to see it, send me an email and I'll send it direct to your email address.)
 

Attachments

  • SAPPHIRE MEETING STORY 2021.pdf
    133.2 KB · Views: 43

henryeng

Member
Joined
Apr 26, 2021
Messages
41
More  
Main Amp
McIntosh MA8900
Universal / Blu-ray / CD Player
McIntosh MCD550
Front Speakers
Goldenear Triton One.R
OK....I think the pdf DID post this time. ? OK ?
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
That's very interesting... and I did that same thing to someone else (won't call any names, but some might remember it). He thought I made a change, described it, but there was no change. No doubt our mind plays a lot of tricks on us, and it's one of the hardest things to admit and/or get past the realization of what's really happening. Some will never ever admit it or realize it.

Here it is for those that don't want to open the file (some are very protective against such):

The Hollywood Sapphire Group Program by Ron Streicher, c. 1995.
By Hank Landsberg
July, 2019

The Hollywood Sapphire Group is an organization of professional audio engineers in the Los Angeles area. HSG was founded in 1946. (See http://www.hollywoodsapphiregroup.com/images/documents/aes.pdf) HSG has about 70 active members who meet monthly for dinner and an informative program about audio recording, music production, professional audio equipment, and other pro-audio related topics. The membership consists of highly experienced recording engineers, equipment designers, equipment manufacturers, and more recently, other professionals working in the video and television industries. Membership is by invitation only: you must be a bona fide audio professional with experience and references to be considered for membership. Sales people are not allowed to join. I have been a member of the Sapphire Group since 1978, invited by colleague Steve Guy, co-owner of Location Recording Services in Burbank, CA.

In short, the Hollywood Sapphire Group has some of the most experienced and objective pairs of “golden ears” in the audio business. Some years ago, we had our monthly dinner at Genio’s Restaurant in Burbank. The meeting was well attended, lead by our “De facto Chairman” Olly Berliner (grandson of Emile Berliner, inventor of the “flat” phonograph record).

Our program for this meeting was presented by long-time Sapphire member Ron Streicher. Ron is a respected recording engineer with decades of experience recording live performances of classical and orchestral music. He has custom-built much of his recording gear to meet the stringent demands of his clients.

Ron’s Sapphire program this evening was an “A-B” comparison of two audio circuits that would be auditioned, compared and critiqued by the HSG membership.

No other information about the circuits was provided. We didn’t really know what we were about to hear. Ron had a simple “A-B” switching device that could quickly switch between circuit A and B. Switching from A to B (or B to A) introduced a ½ second of silence during the changeover, with red and blue LEDs indicating which circuit we were hearing. The A-B switcher let us easily hear and compare the two circuits.

Ron began the program, playing well recorded music through professional studio monitor speakers. As various music tracks played, Ron switched between A and B, and us golden-eared listeners made mental notes of the differences we heard between the two circuits. After about 15 minutes of listening, there was much discussion among the membership, describing the audible differences between A and B. Some heard a difference in frequency response; some heard differences in distortion or clarity. Many liked one circuit over the other. Only a few Sapphire members admitted they couldn’t really hear much or any difference at all.

Now it was time for “the big reveal”: what were the circuits or equipment we were comparing?

Ron now explained that there really was only one “circuit”: the audio source was looped through the switcher only so it could insert the ½ second of silence during the changeover. There was no “A” and “B”. There was absolutely no change in the audio circuitry or equipment during the entire listening session.

We were dumbfounded. We had been listening to the same gear during the entire comparison. There was, obviously, absolutely no audible difference between A and B because A and B were the same. The only thing that changed when Ron switched between A and B was the color of the LEDs.

We’d been fooled! The industry’s most experienced, objective, and trusted ears had been conned. We heard “differences” because we expected to. We “heard” things that simply didn’t exist.

And this note from Ron, today: FYI: In addition to the HSG I've given this presentation to several AES Section meetings both in the US and abroad. Always with similar results.

Hearing is a highly subjective process, and is easily influenced by expectations, biases, FBLB*, peer pressure, and other intangibles. (*FBLB = Fear of Being Left Behind)

Perhaps the most prevalent reason we audiophiles “hear differences” between different gear, cables, etc. is because we want to hear them. We expect to hear differences… so we do, whether they exist or not!

We’re very good at fooling ourselves for several reasons:
1. We don’t want to admit that we can’t really hear any improvement after spending $1,000 on new speaker cables (or other interconnects for which science and physics do not support suppliers’ claims of improvement).
2. We don’t want to admit to our friends that we don’t hear things that they claim to hear.
3. We don’t want to admit that we’ve been conned by snake-oil salesmen.
4. We want to inflate our ego and impress our friends with our audio system.
5. We are conditioned to associate cost with performance. Anything expensive must be better. And anything insanely expensive must be insanely better.
6. (Add your own reasons here!)

Keep this in mind the next time you’re tempted to replace your power cables or AC outlets with “audiophile grade” stuff that’s stupidly expensive.

http://www.hollywoodsapphiregroup.com/
 

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
In my world anything before your sighted AB test in 2020-21, like Genes 2008 SC07 review, is a source of bias.
Priori knowledge.


Actually you don't, because they use single or multiple comparisons, ABX and ABC (anchor).
They are in no way trying to establish whether there are difference or not between loudspeakers (there is!!), but correlating measurements to preferences.
An ABX of your 2 amps, should be a difference, or really no difference test.


Actually a technically literate view would be that your test was sighted non-randomized/highly problematic AB switching, unmatched with some kind of non-constant voltage issue, possibly caused by a lack of isolation between DUTs, etc, etc, etc. vs Sonnies designed by a knowledgeable, technically literate EE AVA ABX box, made very specifically for these exact kind of tests so that all the confounders included in yours weren't missed. The completely false equivalence is noted.


I sometimes forget you're the veteran EE/perceptual tester and not a software guy. Forgiveness please. ;)


0.1db is below your or any other human to detect an amp driving speakers, so well chosen. Btw, Frank didn't design these.
And I think by now we all know why you can't cite the 0.1db reference/paper/etc you claim. :)
Reality is its higher, especially for music w amp>speakers/room.
View attachment 41730

https://www.sciencedirect.com/topics/engineering/just-noticeable-difference

Actually, I had read great reviews and suggested the SC-07. Long after we had swapped out the SC-07 was it discovered that there were issues driving 4 Ohm loads. Of course, had I known you then, you would have assured me that this was sighted bias on our part, when actually, there was a measurable deficiency.

OK I accept that larger volume deviations are required in room, ignoring distortion and other potentially identifiable traits for amplifiers.

There are tube amps that are have 1 dB deviation or more driving difficult loads. I posted such a link.
It would be nice when performing a blind test to evaluate the ability to detect a differences.
A positive case.

Harman evaluates participants for normal hearing and then trains them to identify differences.

Do you think that @Sonnie's test prove that all amps in all rooms with all participants has proved that all amplifiers sound the same? If you do, then that is another kind of confirmation bias.

- Rich
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
Do you think that @Sonnie's test prove that all amps in all rooms with all participants has proved that all amplifiers sound the same? If you do, then that is another kind of confirmation bias.

- Rich
I'm not sure what AJ will say, but since you "atted" me... lol... I do believe our evaluation lends credibility to at least most amps sounding the same if operated within their boundary limits, being we tested a good sampling of low, mid and high-end amps. It goes along with several other evaluations that have shown the same results. And we still have none with music that have proven otherwise. Certainly it does not provide the definitive answer because we haven't tested all amps.

I've always wondered why not one single person was willing to take the 10 grand... not even one.

LINK: Science and Subjectivism in Audio

Any amplifier, regardless of topology, can be treated as a “black box” for the purpose of listening comparisons. If amplifiers A and B both have flat frequency response, low noise floor, reasonably low distortion, high input impedance, low output impedance, and are not clipped, they will be indistinguishable in sound at matched levels no matter what’s inside them. Of course, some of the new “alphabet soup” topologies do not necessarily satisfy those conditions.

I really believe that all this soul-searching, wondering, questioning, agonizing about amplifiers is basically unproductive and would be much more rewarding if applied to loudspeakers instead. For various reasons that I have discussed in the past, people are more willing to change amplifiers than loudspeakers. That’s most unfortunate because a new and better loudspeaker will change your audio life but a new amplifier will not.

—Peter Aczel, Editor & Publisher, The Audio Critic
There has been a lot of hot chatter on the E-mail circuit over the past couple of months about the Steve Maki and Steve Zipser challenge in Miami. I thought you would appreciate a complete recount of the events. Zipser, a high-end salon owner, had issued a challenge that he would pay the airplane fare of any interested party who wanted to see him prove he could hear the differences between amplifiers.

On Sunday afternoon, August 25th, Maki and I arrived at Zipser's house, which is also Sunshine Stereo. Maki brought his own control unit, a Yamaha AX-700 100-watt integrated amplifier for the challenge. In a straight 10-trial hard-wired comparison, Zipser was only able to identify correctly 3 times out of 10 whether the Yamaha unit or his pair of Pass Laboratories Aleph 1.2 monoblock 200-watt amplifiers was powering his Duntech Marquis speakers. A Pass Labs preamplifier, Zip's personal wiring, and a full Audio Alchemy CD playback system completed the playback chain. No device except the Yamaha integrated amplifier was ever placed in the system. Maki inserted one or the other amplifier into the system and covered them with a thin black cloth to hide identities. Zipser used his own playback material and had as long as he wanted to decide which unit was driving the speakers.

I had matched the playback levels of the amplifiers to within 0.1 dB at 1 kHz, using the Yamaha balance and volume controls. Playback levels were adjusted with the system preamplifier by Zipser. I also determined that the two devices had frequency response differences of 0.4 dB at 16 kHz, but both were perfectly flat from 20 Hz to 8 kHz. In addition to me, Zipser, and Maki, one of Zip's friends, his wife, and another person unknown to me were sometimes in the room during the test, but no one was disruptive and conditions were perfectly quiet.

As far as I was concerned, the test was over. However, Zipser complained that he had stayed out late the night before and this reduced his sensitivity. At dinner, purchased by Zipser, we offered to give him another chance on Monday morning before our flight back North. On Monday at 9 a.m., I installed an ABX comparator in the system, complete with baling-wire lead to the Yamaha. Zipser improved his score to 5 out of 10. However, my switchpad did develop a hang-up problem, meaning that occasionally one had to verify the amplifier in the circuit with a visual confirmation of an LED. Zipser has claimed he scored better prior to the problem, but in fact he only scored 4 out of 6 before any difficulties occurred.

His wife also conducted a 16-trial ABX comparison, using a 30-second phrase of a particular CD for all the trials. In this sequence I sat next to her at the main listening position and performed all the amplifier switching functions according to her verbal commands. She scored 9 out of 16 correct. Later another of Zip's friends scored 4 out of 10 correct. All listening was done with single listeners.

In sum, no matter what you may have heard elsewhere, audio store owner Steve Zipser was unable to tell reliably, based on sound alone, when his $14,000 pair of class A monoblock amplifiers was replaced by a ten-year old Japanese integrated amplifier in his personal reference system, in his own listening room, using program material selected personally by him as being especially revealing of differences. He failed the test under hardwired no-switching conditions, as well as with a high-resolution fast-comparison switching mode. As I have said before, when the answers aren't shared in advance, "Amps Is Amps" even for the Goldenest of Ears.

Tom Nousaine
Cary, IL
Richard Clark $10,000 Amplifier Challenge FAQ

by Tom Morrow
Written 6/2006
The Richard Clark Amp Challenge is a listening test intended to show that as long as a modern audio amplifier is operated within its linear range (below clipping), the differences between amps are inaudible to the human ear. Because thousands of people have taken the test, the test is significant to the audiophile debate over audibility of amplifier differences. This document was written to summarize what the test is, and answer common questions about the test. Richard Clark was not involved in writing this document.

The challenge


Richard Clark is an audio professional. Like many audiophiles, he originally believed the magazines and marketing materials that different amplifier topologies and components colored the sound in unique, clearly audible ways. He later did experiments to quantify and qualify these effects, and was surprised to find them inaudible when volume and other factors were matched.

His challenge is an offer of $10,000 of his own money to anyone who could identify which of two amplifiers was which, by listening only, under a set of rules that he conceived to make sure they both measure “good enough” and are set up the same. Reports are that thousands of people have taken the test, and none has passed the test. Nobody has been able to show an audible difference between two amps under the test rules.
This article will attempt to summarize the important rules and ramifications of the test, but for clarity and brevity some uncontroversial, obvious, or inconsequential rules are left out of this article. The full rules, from which much of this article was derived, are available here and a collection of Richard's comments are available here.

Testing procedure


The testing uses an ABX test device where the listener can switch between hearing amplifier A, amplifier B, and a randomly generated amplifier X which is either A or B. The listener's job is to decide whether source X sounds like A or B. The listener inputs their guess into a computerized scoring system, and they go on to the next identification. The listener can control the volume, within the linear (non-clipped) range of the amps. The listener has full control over the CD player as well. The listener can take as long as they want to switch back and forth between A, B, and X at will.

Passing the test requires two sets of 12 correct identifications, for a total of 24 correct identifications. To speed things up, a preliminary round of 8 identifications, sometimes done without levels or other parameters perfectly matched, is a prerequisite.

Richard Clark normally has CD source, amplifiers, high quality home audio speakers, and listening environment set up in advance. But if the listener requests, they can substitute whatever source, source material, amplifiers, speakers (even headphones), and listening environment they prefer, within stipulated practical limits. The source material must be commercially available music, not test signals. Richard Clark stipulates that the amplifiers must be brand name, standard production, linear voltage amplifiers, and they must not fail (e.g. thermal shutdown) during the test.

Amplifier requirements


The amplifiers in the test must be operated within their linear power capacity. Power capacity is defined as clipping or 2% THD 20Hz to 10kHz, whichever is less. This means that if one amplifier has more power (Watts) than the other, the amplifiers will be judged within the power range of the least powerful amplifier.

The levels of both left and right channels will be adjusted to match to within .05 dB. Polarity of connections must be maintained so that the signal is not inverted. Left and Right cannot be reversed. Neither amplifier can exhibit excessive noise. Channel separation of the amps must be at least 30 dB from 20Hz to 20kHz.

All signal processing circuitry (e.g. bass boost, filters) must be turned off, and if the amplifier still exhibits nonlinear frequency response, an equalizer will be set by Richard Clark and inserted inline with one of the amps so that they both exhibit identical frequency response. The listener can choose which amplifier gets the equalizer.


FAQs:

How many people have taken the challenge?


Richard Clark says over a couple thousand people have taken the test, and nobody has passed. He used to do the test for large groups of people at various audio seminars, and didn't charge individuals to do the test, which accounted for the vast majority of the people who did the test. Around 1996 was the last of the big tests, and since then he has done the test for small numbers of people on request, for a charge ($200 for unaffiliated individuals, $500 for people representing companies).

When did the challenge start?


Sometime around the year 1990. Richard Clark says in a post on 7/2004 that the test with the $10,000 prize started about 15 years ago.

What were the results of the test?


Nobody has ever successfully passed the test. Richard Clark says that generally the number of correct responses was about the same as the number of incorrect responses, which would be consistent with random guessing. He says in large groups he never observed variation more than 51/49%, but for smaller groups it might vary as much as 60/40%. He doesn't keep detailed logs of the responses because he said they always show random responses.

Is two sets of 12 correct responses a stringent requirement?


Yes. Richard Clark intentionally made the requirements strict because with thousands of people taking the test, even random guessing would eventually cause someone to pass the test if the bar was set low. Since he is offering his own $10,000 to anyone who will pass the test, he wants to protect against the possibility of losing it to random guessing.

However, if the listener is willing to put up their own money for the test as a bet, he will lower the requirements from 12 correct down to as low as 6 correct.

Richard Clark has said “22 out of 24 would be statistically significant. In fact it would prove that the results were audible. Any AVERAGE score more than 65% would do so. But no one has even done that”.”

Do most commercially available amplifiers qualify for this test, even tube amplifiers and class D amplifiers?


Yes. Nearly all currently available amplifiers have specs better than what are required for the test. Tube amplifiers generally qualify, as do full range class D amplifiers. It is not clear whether Richard Clark would allow sub amplifiers with a limited frequency response.

Besides taking Richard Clark's word, how can the results of the test be verified?


Many car audio professionals have taken the test and/or witnessed the test being taken in audio seminars, so there isn't much doubt that the test actually existed and was taken by many people. One respected professional who has taken and witnessed the test is Mark Eldridge. Because the test has been discussed widely on audio internet forums, if there were people who passed the test it seems likely that we would have heard about it. Sometimes there are reports of people who believe they passed the test, but upon further examination it turns out that they only passed the preliminary round of 8 tests, where levels were not matched as closely as for the final test.

How can audio consumers use the results of this test?


When purchasing an amplifier, they can ignore the subjective sound quality claims of marketers. Many amplifier marketers will claim or imply that their amplifiers have some special topology, materials, or magic that makes the sound clearly superior to other amps at all volume levels. Many consumers pay several times more than they otherwise would for that intangible sound quality they think they are getting. This test indicates that the main determinant of sound quality is the amount of power the amplifier can deliver. When played at 150W, an expensive 100W measured amplifier will clip and sound worse than a cheap 200W measured amp.

Does this mean all amps sound the same in a normal install?


No. Richard Clark is very careful to say that amps usually do not sound the same in the real world. The gain setting of an amplifier can make huge differences in how an amplifier sounds, as can details like how crossovers or other filters are set. When played very loud (into clipping), the amplifier with more power will generally sound better than a lower powered amp.

Most people perceive slight differences in amplitude as quality differences rather than loudness. The louder component sounds “faster, more detailed, more full”, not just louder. This perceptual phenomenon is responsible for many people thinking they liked the sound of a component when really they just liked the way it was set up.

I changed amps in my system to another one with the same measured power and I hear a sound quality difference. Does this show that the test results are invalid?


No. Installing a new amplifier involves setting the gains and crossovers, and any slight change you make to those settings is going to affect how things sound.

Is adding an equalizer just a way of “dumbing down” the better amplifier ?


Richard Clark allows the equalizer to be added to whichever amplifier the listener wants. It can be added to the amplifier that the listener perceives as the weaker amplifier . The EQ is most likely to be used when comparing a tube amplifier (which exhibits slight high frequency rolloff) to a solid state amplifier . In that case Richard Clark says he can usually fashion an equalizer out of just a resistor and/or capacitor which for just a few dollars makes the solid state amplifier exhibit the same rolloff as the tube amplifier, and therefore sound the same. If the tube amplifier really sounded better, then modifying the solid state amplifier to sound indistinguishable from it for a few bucks should be a great improvement.

How might allowing clipping in the test affect the results?


It's impossible to know for sure because that would be a different test that has not been done. But Richard Clark seems to think that in clipping, conventional amplifiers would sound about the same, and tube amplifiers would sound different from solid state amplifiers.

Richard Clark reported that he did some preliminary experiments to determine how clipping sounds on different amplifiers . He recorded the amplifier output using special equipment at clipping, 12db over clipping, 18db over clipping, and 24db over clipping. Then he normalized the levels and listened. His perception was that with the same amount of overdrive, the conventional amplifiers sounded the same. With the same amount of overdrive the tube amplifiers sounded worse than the conventional amplifiers . On the basis of that experiment, he said “I believe I am willing to modify my amplifier challenge to allow any amount of clipping as long as the amplifiers have power ratings (actual not advertised) within 10% of each other. This would have to exclude tube amplifiers as they seem to sound much worse and it is obvious”.

If a manufacturer reports false power ratings, will that interfere with the test?


No. The test is based on measured power, not rated power .

Does this mean that there is no audible difference between sources, or between speakers?


No. There are listening tests that show small but significant differences among some sources (for instance early CD players versus modern CD players). And speakers typically have 25% or more harmonic distortion. Most everyone agrees that differences among speakers are audible.

Does the phrase "a watt is a watt" convey what this test is about?


Not quite but close. Richard Clark has stated that some amplifiers (such as tubes) have nonlinear frequency response, so a watt from them would not be the same as a watt from an amplifier with flat frequency response.

Do the results indicate I should buy the cheapest amp?


No. You should buy the best amplifier for your purpose. Some of the factors to consider are: reliability, build quality, cooling performance, flexibility, quality of mechanical connections, reputation of manufacturer, special features, size, weight, aesthetics, and cost. Buying the cheapest amplifier will likely get you an unreliable amplifier that is difficult to use and might not have the needed features. The only factor that this test indicates you can ignore is sound quality below clipping.

If you have a choice between a well built reliable low cost amp, and an expensive amplifier that isn't reliable but has a better reputation for sound quality, it can be inferred from this test that you would get more sound for your money by choosing the former.

Do home audio amps qualify for the test?


Yes. In the 2005 version of the test rules, Richard explicitly allows 120V amplifiers in a note at the end.

How can people take the test?


They should contact Richard Clark for the details. As of 2006 Richard Clark is reported to not have a public email account, and David Navone handles technical inquiries for him. Most likely they will need to pay a testing fee and get themselves to his east coast facility.

Is this test still ongoing?


As of early 2006 , there have not been any recent reports of people taking the test, but it appears to still be open to people who take the initiative to get tested.

Do the results prove inaudibility of amplifier differences below clipping?


It's impossible to scientifically prove the lack of something. You cannot prove that there is no Bigfoot monster, because no matter how hard you look, it is always possible that Bigfoot is in the place you didn't look. Similarly, there could always be a amplifier combination or listener for which the test would show an audible difference. So from a scientific point of view, the word “prove” should not be used in reference to the results of this test.

What the test does do is give a degree of certainty that such an audible difference does not exist.

What do people who disagree with the test say?


Some objections that have been raised about the test:

  • Richard Clark has a strong opinion on this issue and therefore might bias his reports.
  • In the real world people use amps in the clipping zone, and the test does not cover that situation.
  • Some audible artifacts are undetectable individually, but when combined with other artifacts they may become audible as a whole. For instance cutting a single graphic EQ level by one db may not be audible, but cutting lots of different EQ levels by the same amount may be audible. Maybe the amps have defects that are only audible when combined with the defects from a particular source, speaker, or system.
  • Some listeners feel that they can't relax enough to notice subtle differences when they have to make a large number of choices such as in this test.
  • There is a lack of organized results. Richard Clark only reports his general impressions of the results, but did not keep track of all the scores. He does not know exactly how many people have taken the test, or how many of the people scored “better than average”.
  • If someone scored significantly better than average, which might mean that they heard audible differences, it is not clear whether Richard Clark followed up and repeated the test enough times with them to verify that the score was not statistically significant.
Is there one sentence that can describe what the test is designed to show?

When compared evenly, the sonic differences between amplifiers operated below clipping are below the audible threshold of human hearing.

Links

Note from the author

I wrote this Summary/FAQ because I found that many of the people who disagreed with Richard Clark about the challenge simply didn't have the whole story on the challenge. I originally thought the challenge was flawed even after I read the rules a few times, but after reading lots of comments from Richard Clark, my objections were answered and now I believe that understanding the challenge is a very useful tool for learning what is audible and what isn't. I have no relationship with Richard Clark and have never communicated with him except that I've read his public postings about the challenge. If anyone finds typos or factual errors in this document please contact me.
 

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
I'm not sure what AJ will say, but since you "atted" me... lol... I do believe our evaluation lends credibility to at least most amps sounding the same if operated within their boundary limits, being we tested a good sampling of low, mid and high-end amps. It goes along with several other evaluations that have shown the same results. And we still have none with music that have proven otherwise. Certainly it does not provide the definitive answer because we haven't tested all amps.

I've always wondered why not one single person was willing to take the 10 grand... not even one.

LINK: Science and Subjectivism in Audio

They cannot win that challenge because they have done a fairly good job of described the characteristics that make an amplifier indistiquishable. There some tube amps that would be a bad bet and there are some others that would be worth a shot. However, they would not get through the entry conditions. Such as Gene's chip amp.at 1 watt.

I'll bet they would not let him in the door.
A pro amp driving 100 dB efficient horns might be distinguishable without anything playing. :)

- Rich
 

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
Actually, I had read great reviews and suggested the SC-07. Long after we had swapped out the SC-07 was it discovered that there were issues driving 4 Ohm loads. Of course, had I known you then, you would have assured me that this was sighted bias on our part, when actually, there was a measurable deficiency.
Right, issues possibly heard with "Class D" Pioneer, "confirmed" by measurements 2008.
2020/21: Issues now "heard" with Class D Hypex in a sighted test. I assure you. ;)

OK I accept that larger volume deviations are required in room, ignoring distortion and other potentially identifiable traits for amplifiers.
Great, so non juvenile. Not "required" unless you mean for detection, but making 0.1db increments/accuracy perfectly acceptable. As the EE designed AVA does.

There are tube amps that are have 1 dB deviation or more driving difficult loads. I posted such a link.
It would be nice when performing a blind test to evaluate the ability to detect a differences.
A positive case.
You keep repeating this Strawman as if you believe the myth that differences are never detected in blind tests and only nulls result.
One wouldn't need a blind test whatsoever to "hear" this, umm, "amp". On the same token, a blind test would certainly reveal it.
396JADFIG1.jpg

This has zero relevance to your 2 amps.

Do you think that @Sonnie's test prove that all amps in all rooms with all participants has proved that all amplifiers sound the same?
No, but your strawman does...and keeps repeating.:rolleyes:
 
Last edited:

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
Right, issues possibly heard with "Class D" Pioneer, "confirmed" by measurements 2008.
2020/21: Issues now "heard" with Class D Hypex in a sighted test. I assure you. ;)

OK, AJ and in 2006 you'd have been up my butt and completely wrong !
I have show measurements of amps that fall outside your audibility criteria and still impossible to accept the possibility.

From this reaction, I think that I gored your ox.

Consider adding this to your signature:
A true believer, impervious to measurements ever at the ready and available to scold and correct the unenlightened, guiding them to the one true faith.

- Rich
 

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
OK, AJ and in 2006 you'd have been up my butt and completely wrong !
You have some strange imaginations Rich.

I have show measurements of amps that fall outside your audibility criteria and still impossible to accept the possibility.
And even stranger strawmen/arguments with self lol

Take Sonnie up on the AVA box offer or just stay away from the whole amp testing thing
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
Okay guys... let's play nice. It's apparent neither will budge, regardless of anything.

Bottom line right now is there is a massive number of objective tests that don't show any differences, and no documented objective tests that do, although some subjective. People can derive from that what they wish... it's each individuals own money. If they believe they hear a difference, let them believe it with or without proof. I bias buy all the time... and I suspect we all do to an extent.
 

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
Some updates:

1) Apparently, the nobosound switch is also sharing a ground. I discovered this when I disconnected the negative on one amp and the channel continues to play. This is worrisome.

2) There is an update to the AVA ABX switch that no longer uses the common ground.

3) The ATI AT525NC is deployed in Maine and doing well. This amp had the best feature set for that site. It runs cool, is backed by ATI that has good reliability and repair services, has plenty of power, and has a trigger. The Sunfire has not trigger and turns off when the center channel only is active, so it had to left on 24/7.

The 1999 Sunfire Cinema Grand is home, and in a preliminary listening session is hard to distinguish from the AHB2. Pretty good for a 22 year old amplifier. Even the front light is working.

- Rich
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
I had a Cinema Grand back in the day... probably mid 90's I'm guessing... loved the front analog look of it too.
 

AJ Soundfield

Active Member
Joined
May 21, 2017
Messages
394
Location
Tampa
More  
Preamp, Processor or Receiver
Yamaha RXA800, Denon AVR-X4500, Lexicon MC10
Main Amp
Hypex Ncores
Additional Amp
Abacus Ampino, Triode Corp TRV-35SE
Computer Audio
AudioEngine D2
DAC
NAD M51
Universal / Blu-ray / CD Player
Yamaha BDA1010
Front Speakers
Soundfields
Center Channel Speaker
Soundfields, KEF Q150
Surround Speakers
Soundfields
Surround Back Speakers
Revel M16
Subwoofers
Soundfield Cardioid Rythmik Servo
Other Speakers or Equipment
AVA ABX
All seems reasonable to me. Yes, Sunfire made good stuff back in the day, Bob Carver is a legend. Had the pleasure of meeting him couple years ago at an audio show, he sat and listened in my room for quite a while which was cool. Not sure about the company that exists as Sunfire today.
Enjoy some tunes Rich.
 

Sonnie

Senior Admin
Staff member
Thread Starter
Joined
Apr 2, 2017
Messages
5,055
Location
Alabama
More  
Preamp, Processor or Receiver
StormAudio ISP Elite 24 MK3 Processor
Main Amp
McIntosh MC1.25KW Monoblock Amps
Additional Amp
StormAudio PA 16 MK3
Computer Audio
Intel NUC w/ Roon ROCK
Universal / Blu-ray / CD Player
Panasonic UB9000 4K UHD Player (for media discs)
Front Speakers
RTJ 410
Center Channel Speaker
MartinLogan Focus C-18
Front Wide Speakers
JTR Neosis 110HT
Surround Speakers
JTR Neosis 210RT
Surround Back Speakers
JTR Neosis 210RT
Front Height Speakers
JTR Neosis 110HT-SL
Rear Height Speakers
JTR Neosis 110HT-SL
Subwoofers
JTR Captivator 2400 x6
Other Speakers or Equipment
VTI Amp Stands for the Monoblocks
Video Display Device
Sony 98X90L
Remote Control
Universal MX-890
Streaming Equipment
FireCube for movies and Lenova Carbon X1 for Roon
Streaming Subscriptions
Lifetime Roon Subscription
Tidal
qobuz
Netflix
Amazon Prime
Satellite System
Dish Joey 4K
Other Equipment
Zero Surge 8R15W-1 | Salamander Synergy Equipment Stand
Reading his white papers on his Crimson 350 monoblocks after hearing them at Axpona made me want to buy a pair, but I never did... chickened out. Those Line Source speakers he had connected to the monoblocks sounded pretty nice too. Not sure they'd fit in my room... might be too tall.
 

RichB

Member
Joined
Jan 1, 2021
Messages
90
More  
Preamp, Processor or Receiver
RMC-1
Main Amp
AHB2
Additional Amp
AHB2
Other Amp
AHB2
Computer Audio
Roon
DAC
UPD-205
Universal / Blu-ray / CD Player
UPD-205
Front Speakers
Revel Salon2
Center Channel Speaker
Revel Voice2
Surround Speakers
Revel Salon2
Subwoofers
Rythmik E22
Screen
LG C9
Remote Control
Pronto
Streaming Equipment
RPI
Streaming Subscriptions
Roon
All seems reasonable to me. Yes, Sunfire made good stuff back in the day, Bob Carver is a legend. Had the pleasure of meeting him couple years ago at an audio show, he sat and listened in my room for quite a while which was cool. Not sure about the company that exists as Sunfire today.
Enjoy some tunes Rich.

My brother and a friend went to a local Hifi store for a meet and greet with Bob.
They both bought amps which he signed for them. I wonder what they are worth.

I have no use for this amp so I will be selling it if I can figure out how to pack it.

- Rich
 

Kal Rubinson

Active Member
Joined
Nov 6, 2017
Messages
256
Location
NYC
1) Apparently, the nobosound switch is also sharing a ground. I discovered this when I disconnected the negative on one amp and the channel continues to play. This is worrisome.
Indeed and it should be used as a speaker switch or, with care, as an amp switch for amps with ground referenced output. Bridged amps don't qualify. As a speaker switch, it's fine.
 
Top Bottom