I made a quick test. I found my old Type 2425 Brüel & Kjær Voltmeter which can measure RMS, AVG, Peak, Peak hold etc.
Normal listening level RMS < 1V
Very high level.....higher than I normally listen 2V RMS.
I tried to really push to higher level than I ever will play then I reached a peak level at 10V.
I can still feel it in my ears.
So if the ACA can ouput 10V at peaks it will be all I ever need. Seems the 300B amp is good at deliver peak voltages.
Normal listening level RMS < 1V
Very high level.....higher than I normally listen 2V RMS.
I tried to really push to higher level than I ever will play then I reached a peak level at 10V.
I can still feel it in my ears.
So if the ACA can ouput 10V at peaks it will be all I ever need. Seems the 300B amp is good at deliver peak voltages.
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89db speakers should be plenty for the near field with the ACA. I had my Nola clones hooked up and it was actually loud enough in my 11' x 14' listening area. Also had my JBL S38II's hooked up initially, which IIRC, are 89db speakers. The Nolas are a 4ohm load too. Granted, I am using subwoofers/separate amp with the Nolas and the Tempests.
Desktop? Unless you listen really, really, really, really loud you’ll be completely fine.
I would say good decision. While I have loved all my DIY Pass amps, F5 and F6 are the least favorite. Don't misunderstand, they are all good amps. M2 and Aleph J are flat magic in comparison to me. The BA3 complimentary is an excellent amp as well.
The F6 andF5 are great amps, but the BA3 Complimentary is everything they are, and much more in my opinion. Neither F5 nor F6 have the magic of the M2 or Aleph J. Again, my opinion and yours may vary,
Russellc
Yes, I decided to just play and bought just the boards and stuffed them. It is the culmination of years of playing with Zen amplifiers for Nelson. Really nice sounding considering the price. I did use a linear supply for testing and listening to it.
As far as power wise, you are mainly listening to 1/2 watt on peaks. Are you surprised?
So it is "only" nice sounding relative to its price? .....not nice sounding in absolute terms?
A few post above I measured the voltage output from my 300B amp. Normal listen level I was below 1V output (I have 6 ohm speakers). Playing louder than normal I had about 2V RMS output. Then I turned really up for the volumen to level I will never play and a level that is really bad for the ears. Here I reached a peak output at 10V.
I was not surprised that I only need a few Watts as I knew that a 2 x 3.5 W 2A3 amp probably would be sufficient but I was a bit surprised that I was below 1V RMS at normal listening leve.
As you can see from the attached picture I have started the "ACA journey". I will also build a linear supply and I have some other plans also regarding output capacitor etc. So it will take a while before I am at the end. It will be two mono blocks. In the moment I am just make som experiments how to place components.
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The only reason I'm reluctant to build the M2 is due to me building (in the process) the Aleph J. From all reports the sound is kinda similar. I want all the different flavors so figure ill build a F6, Vfet and a BA-3 and have a good mix of flavors.
If you start building another one before you finish the last one, you will
end up like me.
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Yes...maybe.....I was just a bit disappointed to hear the ACA is "only" nice compared to its price. Is that good or bad or what does it tell about the sound?
I am quite confident it will sound good on my speakers as they need little power and it seems even "hard core" FirstWatt builders build the ACA.
It seems to have something in common with my 300B in simplicity which
now is simpler than the schematic as the 100R humpot has been removed and 7805 is now a Rod Coleman current generator. Know this is not a tube forum......but the ACA could look a bit like a "Solid State tube amp" and the reason I want to build it ....I would never build a bipolar class A/B PP amp.....I have had plenty of those
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Yes, and I already made the first modification as the NFB resistors are 33.2k and 121k HOLCO 0.1 % types to get a little higher input impednace. I will start with passive preamp and develop from there. Therefor I needed a bit higher input impedance. I am a bit unsure if it wil cause more noise as there must be a reason why a relative low input impednace was choosen from the start. But it can be changed if it does not work. Then a preamp could be the next project.....after the ACA. My DAC also have a preamp mode.....it is just not so good as it is done in digital domaine in the DSP.
A lot of it I have read. There are many posts......
I have not found info why 10k of input impedance was choosen......but ZM wrote that it was possible to double up the NFB resistors and I have 3 times the values.....so hope it is ok.
Yes...maybe.....I was just a bit disappointed to hear the ACA is "only" nice compared to its price. Is that good or bad or what does it tell about the sound?
I am quite confident it will sound good on my speakers as they need little power and it seems even "hard core" FirstWatt builders build the ACA.
It seems to have something in common with my 300B in simplicity which
now is simpler than the schematic as the 100R humpot has been removed and 7805 is now a Rod Coleman current generator. Know this is not a tube forum......but the ACA could look a bit like a "Solid State tube amp" and the reason I want to build it ....I would never build a bipolar class A/B PP amp.....I have had plenty of those
The ACA sounds very nice. I could live with these amps from here on out. It's been on an average of 7hrs every night. Over the weekend I really cranked them for some music marathon listening. They are playing as I type this.
Some people that build a lot of electronics may take some of these simpler circuits for granted but, as a critical listener, these amps can be considered as good as it needs to be.
To the contrary, simple amps that sound as good as these do should make one question instead, what it is we pay thousands of dollars for otherwise.
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