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Amp Camp Amp Pre-Orders

Sal1950

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#1
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#3
I have the original monoblocks with the 19v power supplies and they are great little amps. Dead quiet at idle, don't clip, and I've never heard any type of distortion. They have to be paired with the right speaker however.
 

DonH56

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#4
Interesting, but my speakers are less efficient and a difficult load, so I'll Pass... :)
 
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#5
I have 4 of the original ACA's modded up to the latest variant. Great for high efficiency passive speakers or used in biamp or triamp setups running mids and highs. I use a pair to drive compression drivers on waveguides - perfect match as the low voltage gain does not require one to pad down the tweets. Completely silent and if you want to get a taste of the FirstWatt sound, especially the mu follower, this is a great way to experience it without breaking the bank.
 

amirm

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#7
From looking at the schematic:



The output is capacitor coupled due to use of single supply voltage. So bass performance is not going to be great. It says it has flat response (0.5 db) down to 10 hz but I am not sure I believe that.
 
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#8
Folks, these are flea watt "designer" amps from Nelson Pass. Since they won't be powering subwoofers, I don't think performance to 10 Hz really matters. The parts and circuit topology's used are "designed" to give a certain distortion spectra to color the sound. In this case, the ACA's sonic signature is similar to the commercial product Aleph J. Using subjective terms, the amp is warm or "tube like" sounding, with a low damping factor.

Nelson offers amps with lower distortion and a higher damping factor like the F5. So if one is looking for vanishing low distortion figures, the ACA is not the amp for you. But if you like the sound of low watt tube amps, but don't want the hassle of tubes, this may be a fun amp to try.

Look, I am not trying to defend Nelson's designs, but there is a reason for his madness and why most folks like the SQ of these amps. It's all about having fun, right :)
 

Sal1950

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#9
Look, I am not trying to defend Nelson's designs, but there is a reason for his madness and why most folks like the SQ of these amps. It's all about having fun, right :)
Yep, Nelson freely admits these boutique designs are toys he plays with to roll a certain desired sound into the amp. Want that Triode, SET or OTL sound in a SS design and he's got something that will come close. ;)
 
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#11
@stunta its the distortion spectra that is both frequency and power output dependant. So, it is not tone controls... However, the "sound" could be replicated in DSP much like how the massive Studer A800 tape recorders sound can be replicated in DSP: https://www.uaudio.com/uad-plugins/special-processing/studer-a800-tape-recorder.html But that's not the point...

The point of the ACA was for folks to get into DIY'ing their own amplifiers. It is simple enough without the complexity of building a serious power supply with lethal voltages. or machining chassis, etc. If all of that is passe to you, great, choose something else...
 

watchnerd

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#12
Why not achieve the same effect in the digital domain? Wouldn’t it be easier and cheaper to apply tone controls in software versus swapping physical electronics?

If this was the 1970s, I’d say yeah, Pass is cool. Now it all just seems passé.
Exactly.

I admit to liking to a bit of euphonic distortion...at times.

But I don't want that to be hard-wired into my amp, because I don't always want it.

I'd rather handle this at the source / DSP layer.
 

stunta

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#14
Yeah, I guess some folks are in it for the fun of building stuff and the satisfaction they get from it, which is cool. I am not a big fan of putting together amplifiers and have gotten frustrated doing this with even simple kits.
 

Sal1950

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#15
Yeah, I guess some folks are in it for the fun of building stuff and the satisfaction they get from it, which is cool. I am not a big fan of putting together amplifiers and have gotten frustrated doing this with even simple kits.
Personally I miss the days of my youth, building my own gear from Knightkits, Heathkits, etc. Even much of the High End stuff was available in kit form. Starting with Dyna & Eico kits, then if you were a real high roller, kits from HarmanKardon, Fisher, and H. H. Scott were out there. Man how badly I wanted to have the cash to build a HK Citation II power amp but at $159.95 from Allied in 1963 it was just WAY beyond my means.
Then you could easily also assemble your own speakers buying beautiful assembled and finished cabinetry from a number of name manufacturers like Electro-Voice and Jensen, etc, pick your drivers and roll em up.
Those were truly the glory days of High Fidelity. Rigs may not have sounded as good as today, but a hell of a lot more fun to be involved in. ;)
 
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#16
Exactly.

I admit to liking to a bit of euphonic distortion...at times.

But I don't want that to be hard-wired into my amp, because I don't always want it.

I'd rather handle this at the source / DSP layer.
If you read the link that Mitchco provided there is this:

In thinking about the design, I considered whether a “chip amp” might be suitable. This would be an amplifier based around a commercially available integrated circuit in which most of the complexity is hidden inside a single component. This approach looks easier, but is a little less “fundamental” than a design using discrete transistors to form the circuit. If you think of this project positioned on a range of DIY complexity, at one extreme you take a pail of sand and start fabricating your own transistors from scratch. At the other end of the scale you go to the store and buy a Bose system. This project leans toward the former.
 
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restorer-john

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#17
There's absolutely nothing wrong with building amplifiers. I built literally hundreds of various designs over the years. My issue is, it doesn't push the envelope of high fidelity performance, in fact, it goes totally the other way and, as such, it is just a waste of time and money.

It's more about the person who 'designed' it and less about the amplifier itself. Devout followers would go to 'camp' and bang up this little thing and feel all warm and fuzzy inside because they got to meet the man.

8w/ch and 3% THD in 2018 should be laughed at, not lapped up in droves by the paint-by-numbers crowd.

Anyway, I just realised this is a dealer's forum, so I'll say no more. :)
 
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Wombat

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#18
Sometimes I wonder whether Audio is much of a hobby any more but rather mostly an 'interest'.

The DIY activity now seems to be mainly about purchasing and connecting ready-made items. Little knowledge or skill required in construction.
 

Sal1950

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#19
Anyway, I just realised this is a dealer's forum, so I'll say no more.
No issue, I'm the original poster and not a dealer. I just thought it might me of interest to some readers here.

Sometimes I wonder whether Audio is much of a hobby any more but rather mostly an 'interest'.
Today's largest section of "audiophiles" is composed mainly of luxury good collectors trying to impress their friends with the cost of their audio shrine. Promoted by the supporting media who hear the differences in five digit cable$ and six digit amps, all are making a ton of money on markups and advertising revenue.
I do sometimes wonder if the death of this hobby was helped along by the high end media. What low/middle income person could become excited and interested in today's high fidelity by reading Stereophile, TAS, WBF and the like? Your made to feel that if you can't afford to spend a small fortune on it, you might as well not bother. Where would be the pride of ownership in that?
Truth is that todays market you could put together a fabulous sounding complete system for under $1k. At no time in history can so little money buy so much SQ but you'd be hard pressed to find that out. Reading the media you'd think it would sound like a 6 transistor radio.
 
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#20
Dear experts:

Could somebody please share any objective performance data available for the ver. 1.6? Would be interesting to see if its frequency response is indeed 10 - 20 kHz +/- 0.1 dB (I am very much in agreement with Amir here)... Most curious also about its distortion spectrum: 0.7% at 1 Watt, even if it is primarily second order harmonic, seems a bit on the high side...

Would you consider 91 dB sensitivity speakers suitable enough to be driven with such low-wattage amp?

Last, but not least: any listening impressions would be very much in order. Am also wondering about stereo vs. mono blocks sound: any discernible differences?

Please chime in!
 
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