Pass ACA Class A Power Amplifier Review

[amirm]

The attacks go beyond the borders of this amp though. On DIYAudio I was accused of being a typical blogger just wanting a hit in traffic. I was accused of not understanding why this amp was created. These do require a defense so that people are better informed.

 

[Thomas savage]

The attacks go beyond the borders of this amp though. On DIYAudio I was accused of being a typical blogger just wanting a hit in traffic. I was accused of not understanding why this amp was created. These do require a defense so that people are better informed.

So nothing about riding about in a jazzed up work van and being too lazy to weed the garden..

I think you got off lightly there .

 

[pma]

Amir - same rules apply as for sects and cults. No way to explain.

 

[readerA]

First, you should avoid getting upset. It is just about audio and inanimate objects. You lose your objectivity when you speak from point of emotion.

As to your point, you cut out the context of what I said there. Someone mentioned the ACA sounds good. I asked if they had compared it to another amp and found that to be the case. If so, I lectured them , on doing such tests in controlled manner. Finding sonic differences below amplifier limits is very hard to impossible. So we operate from the position of disbelief until supported otherwise.

In my case, I ran into said limits the moment I powered on this amp. It severely lacked power to drive the speaker I used. This kind of observation is not controversial since it is backed by objective measurements that show this amp is equiv. of trying to read by candle lights. Hence the reason the members here didn't demand me running a blind test to prove that.

As an analog I have used before, if you tell your doctor that rubbing garlic on your toes cured your cold, he would ask for controlled testing of that before prescribing it to his patients. But if you said that your nose was running when you had a cold, he would believe you. And not ask for a double blind test.

The notion that this is not understood by you, shows that you need to calm down, control your angst, and allow us to explain the failings in audio and how people become victim to it. We have all been there while you have not been where we are.

I guess it doesn't make sense to try to talk to you, so I'll talk a little bit at you.

It seems you really don't see the point. you're missing the gap between what you say—stuff like being 100% behind whatnot objectivity, and how THEY should compare some gear—and how you seem to conduct your, sorry to mention it again, "listening test".

And even though I still admit that I LIKE this amp, and, believe it or not, don't care that you DON'T LIKE it, I still consider it to be a ridiculous attempt of a evaluation or conclusion. It may pass as opinion.

 

[readerA]

The attacks go beyond the borders of this amp though. On DIYAudio I was accused of being a typical blogger just wanting a hit in traffic. I was accused of not understanding why this amp was created. These do require a defense so that people are better informed.

It's just because you're so ridiculously righteous. The greater part of diyaudio got upset not because you made measurements, or because you did not like it, but because, without proving it, you say that it's crap and you're right and they're wrong.

 

[amirm]

I guess it doesn't make sense to try to talk to you, so I'll talk a little bit at you.

It seems you really don't see the point. you're missing the gap between what you say—stuff like being 100% behind whatnot objectivity, and how THEY should compare some gear—and how you seem to conduct your, sorry to mention it again, "listening test".

And even though I still admit that I LIKE this amp, and, believe it or not, don't care that you DON'T LIKE it, I still consider it to be a ridiculous attempt of a evaluation or conclusion. It may pass as opinion.

It is the nature of the Internet that folks speak like you. I hope you forgive me for not losing sleep over it.

What we do here is of huge value to the audiophile world. Through incredible help of the membership, and access to state-of-the-art measurement gear, and my free time, we are shedding light on gear where sun don't normally shine. That some people are threatened by this online, is to be expected. As long as you are in deep minority -- which you are -- and speaking from position of anger and frustration, I am OK with it.

 

[amirm]

It's just because you're so ridiculously righteous. The greater part of diyaudio got upset not because you made measurements, or because you did not like it, but because you say that it's crap and you're right and they're wrong.

Your doctor is not righteous for lecturing you on how medicine works as opposed to what crappot cures you have read online. Same with me. I used to do this work professionally where my livelihood and reputation of a major tech company depended on our impressions of audio technology being right. You on the other hand, can be wrong and nothing will happen. Heck you are not even using your own name so you can say whatever and there is no impact.

As to the rest, the damning part of my assessment are the objective measurements. These measurements actually show better performance than Nelson Pass himself made. No one has disputed them, nor provided anything better. So you can get upset, complain, etc. but won't change the fact that this amp produced by far the worst performance of any amplifier I have tested:

There is no opinion here. There is no person involved. For those, we can talk about your contributions. Mine are to provide repeatable, defensible data. Based on the entire weight of the audio research and engineering, this amplifier is "crap" to use your wording.

 

[readerA]

As long as you are in deep minority -- which you are -- and speaking from position of anger and frustration, I am OK with it.

Here is the root of it all.

 

[readerA]

Your doctor is not righteous for lecturing you on how medicine works as opposed to what crappot cures you have read online. Same with me. I used to do this work professionally where my livelihood and reputation of a major tech company depended on our impressions of audio technology being right. You on the other hand, can be wrong and nothing will happen. Heck you are not even using your own name so you can say whatever and there is no impact.

As to the rest, the damning part of my assessment are the objective measurements. These measurements actually show better performance than Nelson Pass himself made. No one has disputed them, nor provided anything better. So you can get upset, complain, etc. but won't change the fact that this amp produced by far the worst performance of any amplifier I have tested:

There is no opinion here. There is no person involved. For those, we can talk about your contributions. Mine are to provide repeatable, defensible data. Based on the entire weight of the audio research and engineering, this amplifier is "crap" to use your wording.

has anyone disputed this? hello?

 

[amirm]

And even though I still admit that I LIKE this amp, and, believe it or not, don't care that you DON'T LIKE it, I still consider it to be a ridiculous attempt of a evaluation or conclusion. It may pass as opinion.

I 100% believe you. Pair this amp with a high efficiency speaker, listen at low volume and feed it excellently recorded content and I am sure it will sound satisfying. The issue is that there are amps at a fraction of its price that don't force you to bend over backward to accommodate the poor power capabilities of this amp. Watts are cheap these days. Don't live in the past when 20 watts was a lot. Today we can get very powerful amplifiers and with it, be able to use wide range of speakers, and have incredible performance to boot without it being a room heater.

While you may be satisfied in listening to a little amp you built, my job here is different. It is to find great amplification that is transparent, has ample power to drive vast majority of speakers people may have, and be a good design. We don't share these goals. Instead of understanding this, you get angry that based on my metrics this amp is crap. I have now explained them. Hopefully you don't keep stomping your feet in protest that my assessment is wrong. The fault is yours in not attempting to understand who and what we are about here.

 

[tmtomh]

I guess it doesn't make sense to try to talk to you, so I'll talk a little bit at you.

It seems you really don't see the point. you're missing the gap between what you say—stuff like being 100% behind whatnot objectivity, and how THEY should compare some gear—and how you seem to conduct your, sorry to mention it again, "listening test".

And even though I still admit that I LIKE this amp, and, believe it or not, don't care that you DON'T LIKE it, I still consider it to be a ridiculous attempt of a evaluation or conclusion. It may pass as opinion.

I've just caught up on this portion of the thread, and it seems to me you've been talking-at (as opposed to talking-to) ever since you started posting in the thread.

As for @amirm , it appears you are accusing him of hypocrisy or a double standard. I get why you might see it that way. But it seems you are missing an important point he is trying to make: a listening report that confirms or is consistent with a measurement and a well-known causal relationship, is different from a listening report that contradicts a measurement or would seem to confound a well-known causal relationship (or posit an unknown or unproven causal relationship).

So if an amp is measured as lacking power, for example, it is not only reasonable but also totally unexceptional that a listening report would indicate that the amp could not drive speakers to a given volume level without audibly distorting or otherwise running into audible difficulty.

On the other hand, if that same amp were reported to sound better than other amps, that would (a) contradict the measurements, and (b) appear to confound a well-established causal relationship between sufficient power reserves on the one hand, and distortion-free sound reproduction across the frequency spectrum at decent volume on the other hand.

It doesn't mean that amp does not in fact sound better to you (or whomever). But it does mean that if you want anyone else to think that if they heard or bought the amp they would feel the same way you do, you will have to (a) be very specific about how exactly it sounds better to you, and (b) posit some kind of reasonable explanation for how or why it might sound better.

If you do not do that, then the de facto position of Amir (and many others here including me) is going to be that your listening report is not false or wrong, but rather meaningless to us. If you posit a testable hypothesis for why the amp might sound better, then you will get a more positive or open-minded set of replies.

If you don't like that, that is of course your prerogative. You're free to leave this forum, or stay here and complain, or whatever you like. But if you decide to opt for trying to prosecute an accusation of hypocrisy against the site's owner, you should not be surprised when your prosecution gets little traction or little sympathy from many members here.

And if, following that, you decide it might be appropriate to trash Amir and the general culture here as close-minded and just looking for clicks/hits, you are of course free to do that too - just keep in mind that if you do that trashing here on this forum, eventually you might get removed. (I have zero knowledge of what Amir might or might not do in such a scenario - just speaking in terms of what's possible.)

 

[amirm]

has anyone disputed this? hello?

hello? did you read your own post or did someone else write it for you?

 

[readerA]

hello? did you read your own post or did someone else write it for you?

Nobody ever put the measurements in question. That’s not the point.

Besides, the two replies above were getting to the point, and were actually meaningful to me (even to me)

guess it‘s time for me to leave that place.
Amir, please do yourself a favor and don‘t try to tell others what’s audibly „better“. There‘s no such thing as you should know. Tell them what you think is better, or tell them what your fancy highend gear tells you.
Best wishes and no badmouthing from me anymore.
David

 

[amirm]

Amir, please do yourself a favor and don‘t try to tell others what’s audibly „better“. There‘s no such thing as you should know. Tell them what you think is better, or tell them what your fancy highend gear tells you.

Of course there is. Are you this inexperienced in audio? You don't think an underpowered amplifier can sound bad? Where have you been?

 

[readerA]

Of course there is. Are you this inexperienced in audio? You don't think an underpowered amplifier can sound bad? Where have you been?

I wouldn‘t say so.
nobody would run a QLS with a sun audio, of course. Doesn‘t mean either ain‘t good.
And a 120 W somethingamp ain‘t better than a sun audio.

 

[ta240]

You do have to admit that there is certain gear that when you do a review you know what the end result will be and that result will be a lot of traffic.

This amp never claimed to be anything but what you found it to be.

I still see it absurd to test an amp that is clearly not powerful enough for anyone on this site and doesn't follow the audio profile that people on this site like.

Denying that people can have different tastes in what they listen to doesn't make any sense to me.

Folks are selling dirty water as tasting good. What else can I say?

There are a lot of things that people mix with water and drink that other people would go 'yuck' at. Does that make a mixed drink that you don't like 'dirty water'? Unless I sell it to you as purified water I wouldn't think so. They aren't selling the amp as purified sound.

There are types of music that I can't even begin to understand how people can stand to listen to so I would also imagine that there are audio systems that I also would not enjoy as much as others.

It would not get loud enough for me to tell. See the listening test section. I would be shocked if detail was not lost/sound did not get bright though...

So, then the distortion didn't matter, as long as the amp was loud enough for someone they would be fine.

And then we launch into the speculation:

With so much of it: definitely.

Don't get me wrong, I no longer have my ACA because I didn't enjoy it. But I also no longer have my LM3886DR either for the same reason. But I don't question anyone's desire to listen to either of those. At the same time, in a world where people walk around with 'music' blaring out of their cell phone, wedged into their back pocked, either of those is a huge upgrade.

 

[ta240]

Of course there is. Are you this inexperienced in audio? You don't think an underpowered amplifier can sound bad? Where have you been?

Isn't underpowered a relative term? With variables involving speakers, music choice, room size, desired listening volume, and purpose of the amp? At my desk at work anything that can be heard 15 feet away is considered overpowered. There are no peaks to any music that would need to have more than a couple watts for that situation.

 

[amirm]

I wouldn‘t say so.
nobody would run a QLS with a sun audio, of course. Doesn‘t mean either ain‘t good.
And a 120 W somethingamp ain‘t better than a sun audio.

Before doing this review, I searched for online remarks about it. This is one of the first I landed on:

As you see, his subjective impressions quite well track my objective and subjective conclusions. Other amplifiers are clearly different/better in these regards.

You will see me scoff at underpowered tube amps just as well. So you using those other brands are being immune, is not correct. We don't grade on a curve here. An amplifier needs to not be the limit in your system.

 

[amirm]

Isn't underpowered a relative term?

If given a scenario as I did, no. I listened right in front of the speaker. Used a commercial speaker. And showed how a $75 amplifier could drive the same speaker, in the identical situation to far more satisfying level.

And really in general. If 8 watts was enough or close to enough, vast majority of amplifiers in the market to that level. But as you know, amplifiers come with far, far more power as a rule.

So by just about any convention, this is an underpowered amplifier.

 

[amirm]

You do have to admit that there is certain gear that when you do a review you know what the end result will be and that result will be a lot of traffic.

I actually don't. The highest peak we had in traffic was yesterday with the announcement of JDS Labs new DAC and headphone amps. I didn't predict this. Nor did I predict that the review of the TotalDAC would be popular at all.

What I test is 99% a function of what people send me anyway. As such, there is no game to only test what generates traffic. My interest in this amp came from knowing Nelson Pass and being lectured by his writings as gospel elsewhere. So I thought it would be good to test when the offer was made to me. I didn't expect it to be a popular review as it is a DIY kit which the membership usually does not purchase.

As a rule, I accept 95% of gear that is offered to me for testing. The last 5% refusal is usually due to cost of the gear to send back and forth.

I don't want to paint a picture of sainthood here. I of course love to see our efforts here expand so that I can fund expensive expansion of what we do (e.g. speaker testing). It is just that there is no such motivation behind how the review is written. Or devices that are accepted.

Your assertion therefore hits below the belt, and is uncalled for. Find another way to argue your point than mischaracterizing what I am doing here. This site runs without advertising, and sponsorship out of extreme concern for independence. That you still spit on my efforts as having nefarious intentions, is very disappointing.