I need a rather simple (but not dead simple) around 30W amp. Class AB, I've got a 225VA transformer with dual 21vac secondaries and heatsinks. Load range from 4 to 8 ohms.
Among possible choices there are the ESP project 3A and 101, the death of gainclone new thread or simply a chop amp. I'd prefer something on the punchy side, it's to wake up a pair of wharfedale diamond 8.1 on a small room.
Among possible choices there are the ESP project 3A and 101, the death of gainclone new thread or simply a chop amp. I'd prefer something on the punchy side, it's to wake up a pair of wharfedale diamond 8.1 on a small room.
Hi 00940,
I can speak of the P3A. It is a reasonably simple amplifier to build. Many in the DIY Audio community have built it and have been very happy. I enjoy mine immensely. I am not sure it will wake up a pair of Wharfdale Diamond 8.1 (86db aren't they?) but the amp is 60W into 8 ohms. I am using Floorstanders in a 20Ft+ room and it fills it with sound with no stress at all. Quite cheap to build too. I am currently building the P101 (on and off efforts I'm afraid), this I think is more expensive.
Hope this is helpful.
Cheers.
Brownlow
I can speak of the P3A. It is a reasonably simple amplifier to build. Many in the DIY Audio community have built it and have been very happy. I enjoy mine immensely. I am not sure it will wake up a pair of Wharfdale Diamond 8.1 (86db aren't they?) but the amp is 60W into 8 ohms. I am using Floorstanders in a 20Ft+ room and it fills it with sound with no stress at all. Quite cheap to build too. I am currently building the P101 (on and off efforts I'm afraid), this I think is more expensive.
Hope this is helpful.
Cheers.
Brownlow
Don't disregard the chip amps like the LM3875 and LM3886 as they can surprise.... they did for me anyway and made me throw my P3A out. That power supply is ideal for those.
http://www.chipamp.com/
http://www.specializedkits.com/
http://www.chipamp.com/
http://www.specializedkits.com/
rabbitz said:
Interesting, I found the opposite but there wasn't much in it either way. Out of curosity, what output transistors did you use? I have a feeling that there might be a reasonably wide range of performance with P3As depending on component choices.
Anyway, either would be good choices IMHO. The chipamp kits rabbitz pointed out would definitely be easier.
regards
Yes, the Symasym 5 would be a good, a very good solution.
I had a chance to build the 3875, 3886 and finally the 4780 and
none of them satisfied me. For this latest one I even bought
the board set from Brian and, frankly, I didn't even try to complete
it as disapointed I was with the sound.
However, in my quest for a good amplifier I found the Symasym,
and yes, this is an amplifier anybody can be proud of.
A winner!
I had a chance to build the 3875, 3886 and finally the 4780 and
none of them satisfied me. For this latest one I even bought
the board set from Brian and, frankly, I didn't even try to complete
it as disapointed I was with the sound.
However, in my quest for a good amplifier I found the Symasym,
and yes, this is an amplifier anybody can be proud of.
A winner!
Greg Erskine said:
Hi Greg
One P3A on the newer PCBs using MJL21193/4 as well as better quality components through out, using a Harbuch 300VA 25+25, 4 x 4000uF caps and was beaten easily by the other P3A on older PCBs using TIP3055/2955 with very average components, using a Altronics 80VA 18+18, 2 x 5600uF caps. Figure that out.
I preferred the P101 over the P3A, but of course personal tastes come into it, but my AKSA 55N+ is still the favourite.
From my experience, the chipamps I've built (LM3875, LM4780) are very system dependant, but partnered with the right speakers, they shine.... wrong speakers (load????) and very ordinary.
Cheers
This one 25 Watt / 8 Ohm amplifier I want to build.
Maybe I'll come around to it, some time.
Easy to find components:
- BC560C, BD139, BD140 and IRF530/IRF9530
- Trafo ( 1 channel I think ) 2x25V 120 VA
- Output bias recommended: 100mA
It is nothing spectacular, but as far as I can judge, basically a good amplifier
with very nice and low distortion figures.
RED Free Circuit Designs
I'm very pleased with my P3A. We compared it to an LM3875 amp and both felt it was better (although that might have been power supply). Upgraded output transistors make a big difference.
I've now built three of them and they all sound very good. I've built a number of chip amps as well and none sound as good.
Chip amps are definitely easier, however, so it depends how ambitious you feel.
I've now built three of them and they all sound very good. I've built a number of chip amps as well and none sound as good.
Chip amps are definitely easier, however, so it depends how ambitious you feel.
Hi,
IRF output devices and resistor bias control are not good friends.
The vertical FETs need a temperature compensated output bias controller.
You risk thermal runaway and blown output stage if run the way you show. The only thing that might save this design is a very oversized heatsink, but you give no guidance on this.
Newcomers,
do not copy this design without getting further advice.
IRF output devices and resistor bias control are not good friends.
The vertical FETs need a temperature compensated output bias controller.
You risk thermal runaway and blown output stage if run the way you show. The only thing that might save this design is a very oversized heatsink, but you give no guidance on this.
Newcomers,
do not copy this design without getting further advice.
AndrewT said:
This was also a thought I had, when studying this circuit.
Thermal runaway.
Amplifier has been tested and distortion figures are given.
Size and type of heatsink is not mentioned in the short building description.
What is strange, is this circuit is widely spread around at other websites,
and has been around for many years now.
If any problems, this should have been corrected at this source website.
I cant figure it out .....
Projects from this Site?
Hello
I build the ClassA 5W Amp from this Site 3 times now, third time using the BD911 instead of the small types mentioned. It is really working greatly from the first moment, great design sofar! Despite the Output is getting really HOT (well class A)
I thougt this amp would be interesting too-so what schould one add or redesign to stabilize the concept and get it to work?
What about the bigger desing (amp60) is it reliable or does it have the same Probs concernig thermal runaway?
http://www.redcircuits.com/Page100.htm
Greetings
Black
Hello
I build the ClassA 5W Amp from this Site 3 times now, third time using the BD911 instead of the small types mentioned. It is really working greatly from the first moment, great design sofar! Despite the Output is getting really HOT (well class A)
I thougt this amp would be interesting too-so what schould one add or redesign to stabilize the concept and get it to work?
What about the bigger desing (amp60) is it reliable or does it have the same Probs concernig thermal runaway?
http://www.redcircuits.com/Page100.htm
Greetings
Black
new amp quest
good morning gents;
I am looking for ideas. I may build just one more amp, what's it to be? I have built mostly kit amps; 2a3 monoblocks, chip amps lm3875-3886-4780, the mauro penasa 3886 and my own p2p.
I have an aksa 55 pcb and build guide I got a few years back; I could build this one or is there some better candidates? Which amp should I consider? I believe 50 w/side would minimum .
cheers
doggy:
good morning gents;
I am looking for ideas. I may build just one more amp, what's it to be? I have built mostly kit amps; 2a3 monoblocks, chip amps lm3875-3886-4780, the mauro penasa 3886 and my own p2p.
I have an aksa 55 pcb and build guide I got a few years back; I could build this one or is there some better candidates? Which amp should I consider? I believe 50 w/side would minimum .
cheers
doggy:
rabbitz said:
Thanks rabbitz,
I built my P3A with Toshiba 2SC5200/2SA1943 and 2 x Harbuch 160VA 25+25, 4 x 4,700uF caps (PSU identical to my AKSA).
Yeah, my old AKSA 55 is still my favourite, and it's been played 4 or 5 hours a day for 4 years. I reckon this could be the most burnt-in AKSA in the world.
My chipamps all sounded very good and very similar to me on all my speakers. It didn't seem to matter much what I did. I haven't tried the more complex chipamp circuits though and that may make the difference.
regards
Re: new amp quest
Hi doggy,
Is your AKSA the old version 1.6 like mine? Even the "original" is a very good amp and has bettered everything I have built since.
I'd be curious about a comparision between your AKSA and Mauro Penasa's 3886. As I said in my previous post, MY chipamps, (and P3A, DIGI 125, SC480, DoZ) aren't in the same class as my AKSA, IMHO.
regards
doggy said:
Hi doggy,
Is your AKSA the old version 1.6 like mine? Even the "original" is a very good amp and has bettered everything I have built since.
I'd be curious about a comparision between your AKSA and Mauro Penasa's 3886. As I said in my previous post, MY chipamps, (and P3A, DIGI 125, SC480, DoZ) aren't in the same class as my AKSA, IMHO.
regards
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