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wdecho

A DIY Single Ended Class A Kit

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In the tube section there has been some discussion of diy tube amplifiers. Here is a tried and true SS amplifier with a lot of builds and great results for a Class A amplifier. Most Class A amplifiers get expensive but not this little kit. Most anyone with some skill with your hands can build these little mono blocks. I have not built them, I was brave to begin with and with a lot of luck built an Aleph 30 to start. The cost is a lot greater with larger Class A amplifier and requires bigger more expensive heat sinks and a more expensive PS section. This SS amp will work great with most owners of Klipsch speakers and give you a taste of what SE Class A is all about. If you ever wondered what all the fuss was about with SE Class A this would be a good cheap way to find out and it may suprise you and you might just be satisfied with these mono blocks. There is a long thread about this build at diyaudio from a lot of builds The kit contains everything you need. All is needed is the soldering skills. There is no need to be scared of soldering. It is a task to be learned much as driving a car. I read all the time about people being scared of overheating the parts and it is true too much heat will destroy anything but remember these parts are made to be heated and soldered together. There are plenty of youtube video's on how to solder for a beginner. I hope at least one member tries these little amps.  I thought I would share this with our forum.

 

http://www.diyaudio.com/store/amplifier-kits/amp-camp-kit-23/amp-camp-amp-complete-kit-ver-1-3.html

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That looks like a great project.  $300 for two class A monoblocks seems like a pretty good deal.  They're 5 watts each correct?

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That is very interesting... I am intrigued to try my hand at this.

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This is very interesting...

 

I read the article and like how they supply the power supply pre-done so I dont have to worry about killing myself unless I put a hand in my back pocket... :unsure:

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That looks like a great project.  $300 for two class A monoblocks seems like a pretty good deal.  They're 5 watts each correct?

 

Yes, that is correct. My measurements with my LaScala's are less than 1 watt at peaks. I use a 2 watt SE SET tube amp lately with plenty of power. This is about the simplest SE Class A you can build. It will suprise you with the power it will produce with efficient speakers. They are not for those other wattage hungry speakers we discuss on this forum from time to time. The amps should be good for any speaker with a 95db efficiency for most everyone. The diyaudio store is notoriously slow to restock and these kits just came in after months of waiting. 

 

I just thought to add the guys at diyaudio are great to help if a problem happens with plenty of good advice. It is a international forum with approximately 1,000 people online most anytime day or night. You will find plenty of good advice. This is a link to the build guide.

 

 http://www.diyaudio.com/forums/pass-labs/247361-aca-illustrated-build-guide.html

 

And hear is a discussion thread that is 240 pages long. 

 

http://www.diyaudio.com/forums/pass-labs/215392-amp-camp-amp-aca.html

 

You will not be by yourself with this build just go to the site and ask any question, someone will be glad to try and answer. 

Edited by wdecho

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You will not be by yourself with this build just go to the site and ask any question, someone will be glad to try and answer.

I R Stil Sacre

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I'd like to try it but disposable funds are currently going into a room remodel.  Maybe after the first of the year.

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"I ain't skeered of no amp!"

Handymen should not be afraid of 3 legged critters. A celebrated designer of amplifiers once said he has seen magic smoke many times. Try again when it happens and if you build enough you will most likely see this magic smoke. :)  Just fix the problem and try again, it is a learning process. I think it was Edison who said when building the first light bulb, he did not have failures just hundreds of ways that did not work. 

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The first thing one should build if you do not own or buy a variac is this,

 

 

100 watt bulb for SS and 300 watt bulb for tube builds.

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^tyvm

??? Enlighten me.

 

Never mind I googled it. Your welcome. 

The device will prevent smoke most of the time.  :)

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Buy a surface mount lamp socket and a cheap extension cord.

 

Cut the hot wire and attach both cut ends to the socket.

 

Use a 75W bulb for most home amplifiers.

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I got a little something extra for Christmas at work so I just ordered a kit.

Hopefully we see a build thread along with your impressions.  What do you plan to use them for, I wouldn't mind trying a pair on my Heresies.

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I got a little something extra for Christmas at work so I just ordered a kit.

Hopefully we see a build thread along with your impressions.  What do you plan to use them for, I wouldn't mind trying a pair on my Heresies.

 

 

No immediate plans, I just wanted to try my hand at it.  I have a 15w tube amp on my Cornscalas and may swap it out just to see how it sounds.

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I look forward to hearing your impressions. There is a big following for these little mono Class A amps and I am sure you will have fun putting them together. There is even talk about them having Shade feedback making them behave like a triode tube on the forum. Lots of information on improving them also. 

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it will be next year sometime.  I have a bathroom to finish before I'll have some free play time.

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I got a little something extra for Christmas at work so I just ordered a kit.

Hopefully we see a build thread along with your impressions.  What do you plan to use them for, I wouldn't mind trying a pair on my Heresies.

 

 

No immediate plans, I just wanted to try my hand at it.  I have a 15w tube amp on my Cornscalas and may swap it out just to see how it sounds.

 

 

 

 

Congratulations on taking the plunge and buying an ACA amp kit.  I picked mine up sometime late August of 2013 and I had posted the pictures below to your amp porn thread during November of 2013. 

 

Here are a few specifications for the ACA power amplifier; 

 

14 dB of voltage gain and ~ 6 watts of output with the bias modification that should be a standard part of the version 1.3 kit.  

Input impedance is 10K ohm, and the damping factor is ~ 3.  

Output noise with the switching power supply comes in ~ 100 uV. 

~ 9 dB of feedback. 

At low power levels the distortion is second harmonic, with third harmonic appearing above 2 watts.

 

Actually, I believe that the harmonic distortion structure that Nelson Pass seems to “tweak” into his circuit designs may be what gives this amplifier the “smooth, sweet, yet detailed” sound quality.  I believe Nelson has said a surprising number of people find 3rd harmonics "more detailed" and that low order harmonics such as second or third, are not necessarily the problem; with the problem being more related to the higher order harmonics.

 

With every First Watt amplifier that I’ve listened to, I’ve been somewhat surprised in how the detail of the music seems to be there, along with the general listening smoothness, but the detail just doesn't comes across as strident, etched, or analytic.

 

Of my DIY First Watt builds, I'm currently thinking that the Aleph J may be my favorite, along with the F3 coming in very close.  The F5 is probably my least favorite; however, to me, the F5 detail has bordered on that analytic sound compared to the others.  Actually, I personally tend to like the ACA better than the F5 with the Klipsch speakers I use.  I realize this opinion is against the grain of many F5 listeners; however, I suspect that most are matching much different speakers with them vs what I use.

 

In a cost comparison, the ACA complete kit was ~ $269 when I bought mine in 2013, the F5 ~ $700 cost of parts, and the Aleph J ~ $800 cost of parts.  For the builds I would buy new and decent quality parts from mouser and digi-key; sourcing the PCB, chassis, and back panel parts from diyAudio store; and buying the matched transistor kits from "h_a" and Toshiba JFETs from "Spencer," both participants on the diyAudio forum.  I believe that this method I’ve been using to collecting parts is probably the closest process to buying a complete kit where it comes down to stuffing PCBs, solder wires, turn screws and take voltage measurements.  As far as "instructions," I don't think it gets any better than the "6L6" build guides on the diyAudio forum and the support that 6L6 and others provide when posting a question.

 

 

 

Pass ACA amps.jpg

 

 

 

Pass ACA amps inside.jpg

 

 

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ACA amp.jpg

 

 

 

 

 

 

 

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Edited by Fjd
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