Finally...
I have finally completed assembly of a pair of DACZ layout boards. These were made from the files in post 1354 and turned out very nice from board manufacturer FirstPCB. Thank you to AKSA, Ranchu32 and many others for this design and the sharing of your expertise. Thank you to DACZ for a nice, compact layout and the files to have them manufactured.
These boards were built mostly to the schematic posted by DACZ, with a few substitutions. Q1 is KSA992 with the C and B leads switched. Output transistors are IRFP240 and NJW3281G. Resistors are mostly what I had on-hand and some are larger size than needed. Diodes were used rather than the LED options. The power supply for testing is +- 35V, regulated with LM338 ICs.
The amps sound really good. I know this design has a small amount of even order distortion but I really can't tell, it sounds clear to me. When the music is paused, it is dead silent, even with no enclosure and a gaggle of wires. I'm enjoying these very much.
I have finally completed assembly of a pair of DACZ layout boards. These were made from the files in post 1354 and turned out very nice from board manufacturer FirstPCB. Thank you to AKSA, Ranchu32 and many others for this design and the sharing of your expertise. Thank you to DACZ for a nice, compact layout and the files to have them manufactured.
These boards were built mostly to the schematic posted by DACZ, with a few substitutions. Q1 is KSA992 with the C and B leads switched. Output transistors are IRFP240 and NJW3281G. Resistors are mostly what I had on-hand and some are larger size than needed. Diodes were used rather than the LED options. The power supply for testing is +- 35V, regulated with LM338 ICs.
The amps sound really good. I know this design has a small amount of even order distortion but I really can't tell, it sounds clear to me. When the music is paused, it is dead silent, even with no enclosure and a gaggle of wires. I'm enjoying these very much.
Very nice work, DT73, and a lovely pcb layout from DACZ.
What do you think of the sound quality? Is it warm, and easy to listen?
Does it make your toes tap, and bring a smile?
Hugh
What do you think of the sound quality? Is it warm, and easy to listen?
Does it make your toes tap, and bring a smile?
Hugh
These amps sound great. Imaging is excellent, good bass and pleasantly dynamic for a relatively low power amp. I'm impressed with the low noise level and think I had a preconceived thought that it would not be this clean.
I'm still undecided on the final usage of these amps. It will either be a small stereo integrated amp in a vertical enclosure, like a small computer tower, or "active" type single amps with power supply installed inside speaker enclosures.
I'm still undecided on the final usage of these amps. It will either be a small stereo integrated amp in a vertical enclosure, like a small computer tower, or "active" type single amps with power supply installed inside speaker enclosures.
Me too Christian, nicely done DT73...
A question to you and Hugh..
will a CRC supply work here better than a normal C only supply?
Regards
Prasi
A question to you and Hugh..
will a CRC supply work here better than a normal C only supply?
Regards
Prasi
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In my belief, Prasi, YES.
All my commercial amps use an independent rectifier and CRC for each rail.
It seems to reduce noise, because there is no common tap (CT) in the two (independent) secondary windings.
When you connect a CT to the power earth, and then to the signal earth, you introduce more mains noise to the output of the amp. If you have independent rectifiers, you eliminate connection to the CT, and you can connect the two windings via the power ground at DC. This makes the amp quieter.
Hugh
All my commercial amps use an independent rectifier and CRC for each rail.
It seems to reduce noise, because there is no common tap (CT) in the two (independent) secondary windings.
When you connect a CT to the power earth, and then to the signal earth, you introduce more mains noise to the output of the amp. If you have independent rectifiers, you eliminate connection to the CT, and you can connect the two windings via the power ground at DC. This makes the amp quieter.
Hugh
Same experience here. Two separate windings + two rectifier bridges = potentially less noise / hum from the mains 
Thanks guys, guess i will get my CT toroid re-wound (the good fellow[manufacturer] has agreed), to have separate secondaries and use Project16's nice CRC PSU. Its time to upgrade my main amp to quasi from P3A.
just one more question,
can this amp be driven through a volume pot (50k stepped-pot) with CD player as a source and no preamp/buffer in between?
regards
Prasi
just one more question,
can this amp be driven through a volume pot (50k stepped-pot) with CD player as a source and no preamp/buffer in between?
regards
Prasi
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Hi Prasi, please can you point me to the Project16 psu? I'd like to take a look.
Thanks
Richard
Hi Richard, links here http://www.diyaudio.com/forums/group-buys/301682-crc-power-supply-class-amplifier.html#post4937661
and I am doing the GB with kind permission of Project16, a very nice, humble French gentleman..
Reg
Prasi
A 50k will work fine the way you described however a CD should have no problems driving a 10k pot, which will generate less noise.
Prasi,
Nice project - looks like a very flexible layout. is the GB already full?
Nice project - looks like a very flexible layout. is the GB already full?
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Because its flexible, there is no bom. Users have to customize it.
However better to take it that thread as we don't want to digress from the topic of this thread.
Hi Christian,
Thanks a lot. I will get a 10k step pot. Well, I was worried about some amps / headamps needing a buffer after volume pot. Thanks again for clarifying.
regards
Prasi
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