3e audio A7/A7 Mono Amplifier Review

[Bleib]

I was intrigued by one graph. Could it be that this difference is audible? After all, the sound of metal cymbals extends up to 15-20 kHz.

Notice that those high frequency measurements at very high volume, you are not going to play anything with that much energy through any speakers. So the number is more like "worst case scenario", a more difficult load than any normal music

From Amir's TP RA3 review:
"But if you insist on pumping ear deafening high frequency tones into it in the form of 19 and 20 kHz tones, you naturally get more distortion:"

 

[HighFutility]

I am a bit confused with this one. The power output for 2ch stereo and mono is the same at 4 ohm? Or was this review merely stating that the a7 mono has the same power outputspecs ?

 

[Argentum 05]

I am a bit confused with this one. The power output for 2ch stereo and mono is the same at 4 ohm? Or was this review merely stating that the a7 mono has the same power outputspecs ?

 

[Roland68]

I am a bit confused with this one. The power output for 2ch stereo and mono is the same at 4 ohm? Or was this review merely stating that the a7 mono has the same power outputspecs ?

The A7 and A7 Mono are identical devices.
The A7 has two channels, the A7 Mono only one.
Each channel has the same power output, and each channel uses a TPA3255 in a PBTL configuration.
Simply put, the A7 Mono is half an A7 Stereo.

 

[HighFutility]

The A7 and A7 Mono are identical devices.
The A7 has two channels, the A7 Mono only one.
Each channel has the same power output, and each channel uses a TPA3255 in a PBTL configuration.
Simply put, the A7 Mono is half an A7 Stereo.

Got it thanks.

 

[antcollinet]

I was intrigued by one graph. Could it be that this difference is audible?

Its possible - but exceptionally unlikely as pointed out by @RandomEar

if you want to know for certain - the only way is to invest the time and effort and research to perform a well controlled blind comparison.

 

[Argentum 05]

if you want to know for certain - the only way is to invest the time and effort and research to perform a well controlled blind comparison.

Honestly, no. I'd be interested to find out what I actually heard, but right now, it wouldn't be of practical use to me—I still need two pairs of amps for my bi-amping.
I liked the A7 for the low frequencies. I like the Yamaha for the high frequencies. The result from their combination is better than what I got from the Yamaha alone, across the entire range. This is especially noticeable when I listen to music at 85-92 dB (I sometimes listen at that volume when my wife and kids are out). With the Yamaha alone, distortion was already audible. Now, with the bi-amping, everything is perfect at that volume.
I'd rather spend this time listening to music. I'm a music lover, not an audiophile.

I think the next step in my system's development will be multi-amping, with active crossovers before the amplifier and removing the passive crossovers from the speakers.
But that's someday, later

 

[JW001]

The WIIM PP volume level was set, if I remember correctly, to 43%. I didn't change it.
The A7 had RCA Low, bypass enabled.
The Yamaha AX 892 had CD Direct enabled (bypassing the selector and tone control). But I could adjust the volume.

I played a test track on the A7 and measured the volume using the Spectroid app installed on my smartphone. Then I played the same track on the AX 892 and adjusted the volume control to the same level, with an accuracy of 0.5 dB. The smartphone was placed in front of the speakers and didn't move.
I understand that this method isn't very accurate.

When I heard the difference in high-frequency reproduction, I even gave the A7 the edge during one of the repeats by slightly lowering the volume on the AX 892.
The high-frequency signature is the same—the A7's cymbal sound is shorter. It doesn't have the same richness as the Yamaha. At the same time, the sound is quite detailed. Subjectively, the highs are duller.
This is clearly audible when the sound of metal cymbals is emphasized in silence.
In the music I listen to (punk rock, trash, southern rock, alternative), I could no longer hear the difference.

"Frequency signature" is not a thing. The term is: frequency response, magnitude and phase. Mathematically - a complex function of frequency. If you look at amp's FR, what you see is what you get. Amplifiers are designed by engineers, not by artists .

 

[Argentum 05]

If you look at amp's FR, what you see is what you get.

And, perhaps, even and odd harmonics also influence the sound...
I'd like to know what exactly I should look for in an amplifier's specs to hear those cymbal overtones that I liked in the Yamaha and missed in the A7.

Amplifiers are designed by engineers, not by artists .

Yes, yes. The main thing is that amplifiers aren't designed by marketers


P.S. A good engineer must be a bit of an artist

 

[antcollinet]

I'd like to know what exactly I should look for in an amplifier's specs to hear those cymbal overtones that I liked in the Yamaha and missed in the A7.

There is no point even thinking about that until you've proven that you have actually heard them. Or demonstrated by measurements that one of the amps is performing incorrectly. Otherwise you are just chasing your tail.

If (as is by far most likely) the perceptions are the result of bias then you are going to be looking for something that doesn't exist.

It'll take a long time and a lot of effort to find it.

P.S. A good engineer must be a bit of an artist

As a electronic engineer then project manager with a 35 year career behind me in a blue chip global engineering company - I can tell you that none of the best engineers are also artists (at least not as part of their engineering). They work with knowledge, facts, measurements and skill. Not artistry. Some of the best can look to lesser mortals as if they are dealing in wizardry - they are not - they are just really really good at engineering.

 

[JW001]

P.S. A good engineer must be a bit of an artist

I knew personally people who were a bit of artists and I thought they would be useless as engineers But of course, there are exceptions, although rare. One of them would be Paolo Fazioli, a mechanical engineer, pianist and the maker of famous Fazioli pianos.

 

[Argentum 05]

As a electronic engineer then project manager with a 35 year career behind me in a blue chip global engineering company - I can tell you that none of the best engineers are also artists (at least not as part of their engineering).

Looking at Yamaha audio equipment and motorcycles, can you really believe they weren't designed by artists?
Yes, they are engineers with the highest technical knowledge, but they are also artists, IMHO.

 

[Argentum 05]

I knew personally people who were a bit of artists and I thought they would be useless as engineers But of course, there are exceptions, although rare. One of them would be Paolo Fazioli, a mechanical engineer, pianist and the maker of famous Fazioli pianos.

Also, Leonardo Da Vinci, for example.

If you think about it, engineers and artists share a common ability to create. They are two facets of the mind.

 

[Argentum 05]

There is no point even thinking about that until you've proven that you have actually heard them. Or demonstrated by measurements that one of the amps is performing incorrectly. Otherwise you are just chasing your tail.

If (as is by far most likely) the perceptions are the result of bias then you are going to be looking for something that doesn't exist

Its possible - but exceptionally unlikely

You still admit that the probability isn't 100%, and you also admit that there's a slight chance of hearing a difference in sound, possibly reflected in the graphs I provided of the measurements of the AS701 and A7 (other measurements are also not at all identical). Plus, there's the difference in design and the 25+ year gap.
Why such skepticism about the possibility of a slight difference in sound in the high-frequency range?

 

[RandomEar]

You still admit that the probability isn't 100%, and you also admit that there's a slight chance of hearing a difference in sound, possibly reflected in the graphs I provided of the measurements of the AS701 and A7 (other measurements are also not at all identical). Plus, there's the difference in design and the 25+ year gap.
Why such skepticism about the possibility of a slight difference in sound in the high-frequency range?

Because people regularly failed blind, level-matched listening tests between better and worse amps than yours 40 years ago. People overestimate the reliability of their senses all the time - just like they overestimate their ability to land a plane in an emergency.

Also, as discussed, that theoretical difference in high frequency distortion - which may not even exist, because we lack the data for your specific Yamaha (!) - will never be audible. That level of distortion would not be problematic, even if it happened in our ears most sensitive region around 2 kHz. That's not where it is though. It has been suggested to you to take that Klippel test and see it for yourself - did you try it?

 

[antcollinet]

Looking at Yamaha audio equipment and motorcycles, can you really believe they weren't designed by artists?
Yes, they are engineers with the highest technical knowledge, but they are also artists, IMHO.

You are talking about industrial / aesthetic design - not the engineering (making something work - and work well) design. A different skill set.

 

[antcollinet]

Why such skepticism about the possibility of a slight difference in sound in the high-frequency range?

first - what @RandomEar said.

Second - just because something is technically possible doesn't make it likely enough to consider as real, without better evidence than "I heard it".

Third - what you describe hearing "Longer/shorter sounds" There is no mechanism for amp differenes (very low level noise/distortion) to cause that difference if level matched.


Let me turn the question around

Yes, I understand psychoacoustics and realize I may be biased when listening.

- if that is the case, and given all the explanations you have been provided, why do you refuse to accept that perceptive bias is the likely cause of your perceptions. Don't claim that you do - because all your questions and statements here are based on rejection of that hypothesis.

 

[Argentum 05]

Let me turn the question around

- if that is the case, and given all the explanations you have been provided, why do you refuse to accept that perceptive bias is the likely cause of your perceptions. Don't claim that you do - because all your questions and statements here are based on rejection of that hypothesis.

Because I immediately understood, accepted, and set aside this line of probability, with its perceptual bias, because if there's no evidence to support what I've heard, there's nothing to clarify or discuss.

The second line of probability remains, where there's a difference in high-frequency reproduction.

Both lines equally lead to the biamping setup I currently have (Yamaha for highs, midrange, and A7 for lows).

I'm still purely theoretically interested in the second line of probability. Therefore, I'm using arguments in its favor.
Why do I consider this line of probability plausible enough to be worth discussing?

Previously, there were a couple of situations where, during listening sessions, several people claimed to hear an improvement from replacing the RCA cable with a much more expensive one. But no matter how hard I listened, no matter how hard I tried to isolate individual sounds, I heard no changes, leaving me in the absolute minority.
The same thing happened another time, when listening to two DACs. I again didn't hear a difference, unlike the other two people who claimed there was a significant difference.
This allowed me to have greater confidence in my critical listening skills.

In this case, I did hear a difference (or so I thought) in the high frequencies.

Besides, I was simply interested in this discussion

P.S. I don't know if our conversation is off-topic. If so, I apologize to everyone involved.

 

[somebodyelse]

"Frequency signature" is not a thing. The term is: frequency response, magnitude and phase. Mathematically - a complex function of frequency. If you look at amp's FR, what you see is what you get. Amplifiers are designed by engineers, not by artists .

Expanding on this, load dependency is a thing. Ideally an amp's frequency response wouldn't change with load, but with some amps it does. Depending on the combination of amp and load this may or may not reach audible levels. We see this most often recently with class D amps that don't have post-filter feedback, but it wasn't unusual in valve power amps, and some transistor amps are built that way too (high output impedance). In the class D amps it typically shows up as a difference in high frequency peaking with 4R and 8R resistive loads, with a fairly small difference at the top of the audible range. Most speakers aren't resistive loads though, and when tested with a dummy speaker load the differences usually appear around the crossover frequency. Engineers design to targets, and the target isn't always what you might expect.

 

[Argentum 05]

It has been suggested to you to take that Klippel test and see it for yourself - did you try it?

Not yet. Now that you mentioned it, I looked through your previous posts and found the link. Thank you. I'll need some time to figure it out. Unfortunately, I'm busy right now.