Pass Amp Camp Amp (ACA) Build and Initial Performance. Class A Kit from diyAudioStore. 

Thank you.

Thank you.

Thank you for kind comment. The ACA is a good design. I would like to make a variant that uses a ducted tunnel for the heatsink and a very low RPM fan to manage the heat. Thanks.

Thanks for the kind comments.

Thank you :)

Thanks for the kind comment. It is an interesting amplifier.

Thanks.

Thanks for the kind comments. It is not too bad of a build but probably not for a novice :) As you mentioned, if you can get someone to check your work, you should probably be ok. IMO, use plenty of water soluble flux and make sure to get promptly washed with hot water and it will help the soldering.

Your welcome :)

The manufacturer has very good online assembly instructions. I really only needed to reference the online info a couple of times primarily for the rear panel wiring.

Hello. I first measured the DC input voltage to the amplifier to just make sure that my ground probe was in a good spot. The purpose of this quick test was to make sure that there were no major errors in the assembly process. The input and output are capacitive coupled, so there should be no DC voltage present. No worries. I am always impressed with people that are proficient in more than one language :)

Thanks Dan, you are very kind, your answers have been a great help to me. Keep making videos and teaching us all this. Hello Orlando from Rome.@@DanPattenAudioG33k

That does seem rather expensive.

Stick to English designs and buy locally. Far less expensive and they would not be embarrassed by anything from here in the US.

Yes, you should be able to switch to 24Vdc. However, you will need to re-adjust the bias and note that your amp will run hotter because of increased power.

@@DanPattenAudioG33k thank you very much, I did what was suggested, everything is ok.

Good to hear. Careful of the increased heat dissipation.

The meter should be set to VDC. The positive (red) lead is connected to the middle leg of the transistor and negative (black) lead is connected to ground. Possibly easiest place for ground is where the AC/DC wall adapter power supply comes into the unit.

@@DanPattenAudioG33k ok......many thanks.....🙏😄😄😄

For small rooms and normal listening levels, I would think you would be fine.

A more powerful amp would be nice. The mechanical design gets very expensive with more power as that is a lot of heat to get rid of. It would be interesting to do a tunnel heatsink with a ducted quiet fan.

The Pass Labs X150.8 power amplifier consumes 370 watts just sitting there doing nothing. Only to be used in winter. The X250.8 consumes 500 watts. And those are AB designs. Fuggetaboudit.

The supplied power supply is 24V @ 5A or 120W. You would want a transformer that could supply this amount of power (or more). A 18Vac output transformer when rectified would be close to 24V. (18Vac)(1.414)=25V, subtract diode drops and add large filter caps will get you about 24Vdc. So maybe a 18VAC @ 5A.

@@DanPattenAudioG33k thanks you so much from Viet Nam❤❤❤

The output capacitor is a good quality Cornell-Dubilier unit and the other caps are name brand units. This amplifier uses quality Silpad type thermal pads that are equivalent to paste which also provides electrical isolation without being a mess to use. Resistors are nice metal film types. Nice thing about this design is that all of the components are through-hole so substituting your favorite type of caps would be easy.

I agree that the Class A design is not energy efficient. IMO, they do sound different. It is a matter of opinion if they sound better or not. Some people like them others do not :)

yeah I really didn't see difference in both sounds. would say that nobody could hear difference in a blind test. but I am actually talking about waves they make in an oscilloscope, the distortion etc

​@@pedromiranda7701 I very politely disagree -- I really like the low power Class A designs (25WPC or less) and find they provide more than enough power for my listening and with my speakers (i build higher efficiency 90db+ speakers only). I find they have a grip on the speakers and deal with big transients like higher power Class D and with a pleasing 3-dimensional sound close to the flea power SET tube amps. I've never heard anything like that from a Class AB -- though admittedly I don't think I've ever heard a truly great (or expensive) class AB. I agree though that I would never get a high powered Class A -- the electricity bill would be a killer and it's such a waste, at least for my listening. For bigger rooms and louder listening I agree Class A doesn't make sense. I never use Class A in summer, and even in winter I have them wired up with relays and triggers to go into standby when not in use. Personally I do hear a difference -- and I've only ever listened to the low power Pass Class A designs, and can even hear slight differences between his various designs (and that's with 50 year-old ears). I struggle however to hear differences between most decent DACs though!

@@ssmith954 well, my "use" of sound is based on flatness and high pressure. so I start by setting up tweeters with integrated circuit amps, that are AB. at that point, in max volume and lower possible distortion, I get a certain dB for treble, say 100db in a very flat response in high frequencies. Then I go to configure mid and lower frequencies with the same dB response, to keep everything as flat as possible only by using speaker "engineering", not equalizer. So now I have to get a subwoofer that goes down low about 20hz with air duct. The driver must have a flat response from 20 to, say, 500hz. To do so the speaker usually can achieve only 85db per watt. To make that speaker achieve that same 100db that tweeters, I need a lot of power, that's "impossible" with class A. In this example it'd take about 5 times more power RMS to pump subwoofer linearly with tweeters. If they are with 30w, subs will necessarily use 150w. I do the same calcs for midrange speakers, always measuring distortion and flatness. Most times for a speaker to have that fidelity it may has very low sensibility, around 89db or less. In the end, when everything is set, I get a HiFi system that also is very powerful the way I appreciate. Having just one system for all my needs, from study with Joshua Radin to party with Foo Fighters 😳 today my system is not perfect because I did measured but didn't select the right power for each band. Nevertheless, everything is good and doing well. The pressure is to make my heart beat out of compass. I'm using integrated circuits from Sanyo, achieving a max 310w with 0.5% of THD. My amp has only 1 button and 1 potentiometer, power it on and off and set volume pressure. no equalizer. I'm doing some tests and probably will soon power my subwoofers with a class D amp due to its low distortion in low frequencies. They are powerful and efficient.

@@ssmith954 I'd like if you forgive my bad English grammar and repetitive vocabulary, I'm actually Brazilian and currently studying English, that's hard! 😅

It is a simple design but does sound good. Thanks for watching :)