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Pass ACA Class A Power Amplifier Review

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amirm

amirm

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So, then the distortion didn't matter, as long as the amp was loud enough for someone they would be fine.
Who says? You are saying THD+N this bad (2.4% at just 5 watts) is inaudible? Based on what?
 

m8o

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On a "count the likes" basis alone, if I was readerA I'd STFU and leave in disgrace.

A wise CEO once joked with the Founder infront of me about someone who had dug themselves in a hole. One asked the other, "what's the first rule when you've dug yourself into a hole?". The other replied "Stop Digging!".
 

readerA

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On a "count the likes" basis alone, if I was readerA I'd STFU and leave in disgrace.

Haha.
Just as Amir isn't click-baiting over at diyaudio, I didn't get here for collecting thumbs.

While I'm here, I'll warm up this boring cup of old tea again (a thumb for this, anyone?):

Before doing this review, I searched for online remarks about it.

in his original post is one of Amir's better explanations, where he highlights the arguments which fit his view. Those 'impressions' are totally ok, even if not in favor of the amp.
The (unmarked) second-last bullet goes like this: «These can power my 87dB/2.83v/m sensitivity speakers to decent levels. (…)»
which is what I experienced, too. Not so Amir, who concluded he couldn't barely hear anything. Of course it was a rant, an sarcastic exxageration made to sort of entertain his audience. I, having had the very same impression of a decent level, felt insulted—just as he felt insulted when I pounded his "expertness" (not expertise!)
That's all to it.
 

BDWoody

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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:

index.php


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?

Nope...looks good.
 
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amirm

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The (unmarked) second-last bullet goes like this: «These can power my 87dB/2.83v/m sensitivity speakers to decent levels. (…)»
which is what I experienced, too. Not so Amir, who concluded he couldn't barely hear anything. Of course it was a rant, an sarcastic exxageration made to sort of entertain his audience. I, having had the very same impression of a decent level, felt insulted—just as he felt insulted when I pounded his "expertness" (not expertise!)
That's all to it.
Once again, sensitivity numbers are marketing specs. Don't run with them this way. You only fall in the ditch. I genuinely was shocked how little volume I could get out of this speaker. If you think my subjective remarks are not valid, think of why we should take yours seriously.

Regardless, what he calls "decent level" is likely not what I call decent level. My job is to represent performance of an amplifier to wide range of readers and hence speaker choices. I don't want to say something is loud enough, only to have people buy it and say it is not. The reddit poster won't be called on this the way I will be challenged.

Remember, the objective data backs what I said in how little power this amp has. So your continued challenges on this front are just an empty argument especially when you ignored the rest of what the poster said about this amp which directly dispute yours.
 
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amirm

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Call it "Coca-Cola" and you have a problem.
You really, really need to brush up on your communication skills. Deciphering your posts is next to impossible.
 

Thomas savage

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You really, really need to brush up on your communication skills. Deciphering your posts is next to impossible.
He managed to communicate enough to earn his freedom.

Incoherent and dull , say hello to my boot .
 

maltux

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I want to thank Amirm for the review. I have read through all 22 pages before posting. I was considering building the ACA or a class D amp of some kind. I was skeptical of all the hype given to proponents of each type of amplifier.

Some really good marketing slogans; the first watt is the most important. :rolleyes:

I love the Toronto Maple Leafs. If they do not score as many goals as the other team they lose. I do not like the fact that they lose but it does not change the fact. If the ACA measures poorly it is not a good amp; period. :confused:

I almost clicked the BUY button this summer on the ACA and glad I held off. I have decided on building a IcePower / Ghent amp; (cost: $360).

My favorite forums are this one and the Harbeth User Group. I realize I am new here so my opinion does not count for much. Its okay I have three cats that ignore me.

Cheers!
 

tomchr

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I love the Toronto Maple Leafs. If they do not score as many goals as the other team they lose. I do not like the fact that they lose but it does not change the fact. If the ACA measures poorly it is not a good amp; period. :confused:
Funny you should choose that analogy. I'm a Leafs fan. In fact my old goalie mask (that you can see in my profile picture) features two Maple Leafs logos (1960s and 1987-2015 versions). Sadly, the Leafs' participation in the Stanley Cup finals will depend on their objective performance. Not by how much their fans love them (or they'd have won in my lifetime already!).

Such is life... :)

Tom
 

maltux

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... Sadly, the Leafs' participation in the Stanley Cup finals will depend on their objective performance. Not by how much their fans love them (or they'd have won in my lifetime already!).

Such is life... :)

Tom

HI Tom;

I grew up in Southern Ontario and married an American. My Leafs last won, the Stanley Cup, while I was 3 so I do not remember the glory days either. My cousins moved out to Calgary in the 70's. I guess I am way-off topic. I really love the reviews on this forum. I was shocked at the test results of the ACA. I was seriously considering buying this as a viable option. I hope I have better luck with my Ghent / IcePower (200ASC +200AC) amp. My brother-in-law, named Thom, introduced me to the work of Nelson Pass. He is a tube guy and I am not sold on the virtues yet; maybe some day in the future.

Love the goalie mask - I met Johny Bower at a Buffalo Sabres game and he signed my Wendal Clark jersey.
Cheers!
 
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kannan

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I own the very first version of the AmpCampAmp (ACA) which was DIYed in a group buy at around 150USD.
I have been using it for close to 2 years now with my 89db Infinity speakers which I have modded completely.

Apart from the poor measurement aspects reported by the OP, it is one of the finest sounding low power amps that I have heard and used. I have a fetish for sound stage and details and it produces oodles of it. Its Class A midrange fluidity oozes through and the vocals have a realism to it. Bass is articulate and highs are just about right.
It is driven by the pre of my Teac DAC with Allo Digione Signature as transport.
It is simply said the best 150USD that I have spent.

My other more superior measuring amps including an Adcom, NAD, Sansui and a Mcintosh are now idling. This little ACA on a 19 volt laptop adapter is singing merrily.
 

m8o

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My other more superior measuring amps including an Adcom, NAD, Sansui and a Mcintosh are now idling. This little ACA on a 19 volt laptop adapter is singing merrily.
Please provide me your PayPal.me identity. I'll send you $150 and my shipping address. You can send me the McIntosh amp that sits by idle. ;)
 

SIY

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I own the very first version of the AmpCampAmp (ACA) which was DIYed in a group buy at around 150USD.
I have been using it for close to 2 years now with my 89db Infinity speakers which I have modded completely.

Apart from the poor measurement aspects reported by the OP, it is one of the finest sounding low power amps that I have heard and used. I have a fetish for sound stage and details and it produces oodles of it. Its Class A midrange fluidity oozes through and the vocals have a realism to it. Bass is articulate and highs are just about right.
It is driven by the pre of my Teac DAC with Allo Digione Signature as transport.
It is simply said the best 150USD that I have spent.

My other more superior measuring amps including an Adcom, NAD, Sansui and a Mcintosh are now idling. This little ACA on a 19 volt laptop adapter is singing merrily.

I’m glad you had fun building it, and from Nelson’s goal of entertainment, it’s certainly successful.

The “sonic” evaluation is, of course, useless.
 

kannan

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I’m glad you had fun building it, and from Nelson’s goal of entertainment, it’s certainly successful.
The “sonic” evaluation is, of course, useless.

I have no arguments over any of your opinions. To each his own.
I have shared what I hear out of ACA in my system.
Sonic wise, I like the sound of ACA the most with respect to the speaker I use it with.
I have tried ACA on some power hungry speakers including the Totems and Dynaudio, where it falters with dynamics.
But with proper matching it is a superb sounding amp.
Last month it performed superbly on an Altec Lansing 604B.
 

kannan

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Please provide me your PayPal.me identity. I'll send you $150 and my shipping address. You can send me the McIntosh amp that sits by idle. ;)
An absolute no, though I can understand the jest behind the offer.
 
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