Hello all!
I've finished building my P3A amp and it sounds good, but a little harsh. I know it's a popular amp, so I'm fishing for any mods or upgrades people have done on theirs. Please list any and the results of the mods. Really interested in knowing whether or not I can get a warmer sound out of it.
My P3A:
Power Supply using dual rectification and 12000uF cap banks for the 42V +/- rails.
Solen coupling capacitor.
Mica miller caps.
Metal film resistors.
MJE15034/MJE15035 driver trans
MJL4302/MJL4281 output trans
Thanks!
I've finished building my P3A amp and it sounds good, but a little harsh. I know it's a popular amp, so I'm fishing for any mods or upgrades people have done on theirs. Please list any and the results of the mods. Really interested in knowing whether or not I can get a warmer sound out of it.
My P3A:
Power Supply using dual rectification and 12000uF cap banks for the 42V +/- rails.
Solen coupling capacitor.
Mica miller caps.
Metal film resistors.
MJE15034/MJE15035 driver trans
MJL4302/MJL4281 output trans
Thanks!
blap0220 said:
How much capacitance do you have in the PS? Not just 1200/rail?
A while ago I simulated this amp and the results were less than impressive. But hey, it's only a sim, not real life.
Which did you use for Q4 - MJE15035 or BD140? For what it's worth, the BD140 simmed with lower distortion.
This is what I did to the P3A
Been playing with the P3A for about 4 years on and off and this is the best sounding version I've found which is quite a leap on the others I've tried. The amp is actually quite involving to listen to.
Changed to the 2SC5200 2SA1943 combo, C4, C6 to silver mica, C5 to Nichicon FG, C3 to Hitano EXR. The input cap C1 was where I got a large surprise. Started with 2.2uF Auricap (sounded confused, rolled off each end and lost top end sparkle), then Vishay 1uF MKT (better focus, good top end but bass lacking) and then 10uF Nichicon ES (22uF also worked well) and it all snapped into place. Additional bass and punch, better separation and depth.
100uF caps added on the PCB where the by-pass caps are and those are placed under the PCB..... makes a good difference with the amp more punchy, lively, good transient control and speed, allowing nuances through and throwing the vocals etc out of the mix. There is now depth appearing and the soundstage sounds better.
Power supply was a DX supply by Carlos (aka destroyer x) using 4 x 4700uF Nichicon KG (Gold Tune). This power supply gave it a nice lift and better than the supply just with 4 caps. Uses a single 300VA 25-0-25 for 35V rails.
All the values are standard and I've heard there could be benefits removing or reducing R1, R3.... increasing R2... reducing C4, C6 as the 100pF could be killing the sonics. None of these have been tried and are not my suggestions as they are only what I've read and heard.
Been playing with the P3A for about 4 years on and off and this is the best sounding version I've found which is quite a leap on the others I've tried. The amp is actually quite involving to listen to.
Changed to the 2SC5200 2SA1943 combo, C4, C6 to silver mica, C5 to Nichicon FG, C3 to Hitano EXR. The input cap C1 was where I got a large surprise. Started with 2.2uF Auricap (sounded confused, rolled off each end and lost top end sparkle), then Vishay 1uF MKT (better focus, good top end but bass lacking) and then 10uF Nichicon ES (22uF also worked well) and it all snapped into place. Additional bass and punch, better separation and depth.
100uF caps added on the PCB where the by-pass caps are and those are placed under the PCB..... makes a good difference with the amp more punchy, lively, good transient control and speed, allowing nuances through and throwing the vocals etc out of the mix. There is now depth appearing and the soundstage sounds better.
Power supply was a DX supply by Carlos (aka destroyer x) using 4 x 4700uF Nichicon KG (Gold Tune). This power supply gave it a nice lift and better than the supply just with 4 caps. Uses a single 300VA 25-0-25 for 35V rails.
All the values are standard and I've heard there could be benefits removing or reducing R1, R3.... increasing R2... reducing C4, C6 as the 100pF could be killing the sonics. None of these have been tried and are not my suggestions as they are only what I've read and heard.
Attachments
P3A
Rabbitz, where did you obtain those transistors? I recently acquired P3a boards and will be building this amp. The Elliot website recommends avoiding Toshiba devices because of the high percentage of counterfeits flooding the market. Being new to the DIY electronics side of the audio hobby, I could easily be fooled.
Rabbitz, where did you obtain those transistors? I recently acquired P3a boards and will be building this amp. The Elliot website recommends avoiding Toshiba devices because of the high percentage of counterfeits flooding the market. Being new to the DIY electronics side of the audio hobby, I could easily be fooled.
Re: P3A
Not speaking for rabbitz, but here's where you can get them:
http://www.ampslab.com/trans_2sc5200.htm
LFM said:
Not speaking for rabbitz, but here's where you can get them:
http://www.ampslab.com/trans_2sc5200.htm
LMF
I get my Toshibas from WES Components in Australia. If you buy from a reputable source, there should be no problems.
Here's some info on fakes.
http://www.diyaudio.com/forums/showthread.php?postid=1225392#post1225392
blap0220
I never used the recommended Toshibas and went straight to the 2SC5200 & 2SA1943 as they are used in great amps such as the AKSA55N+, Lifeforce, both of which I have... good enough for me.
I tried the MJL21193 / MJL21194 as well as TIP3055 / TIP2955. I preferred the sound of the TIP devices over the MJL but could only run a low power version. The 5200 / 1943 combo was the best sounding easily.
The use of MJL devices is what started my playing with this amp as the sound was never right and was bettered using the TIP devices, so it became a thorn in my side. It took 4 years only because it was worked on very occasionally.
I get my Toshibas from WES Components in Australia. If you buy from a reputable source, there should be no problems.
Here's some info on fakes.
http://www.diyaudio.com/forums/showthread.php?postid=1225392#post1225392
blap0220
I never used the recommended Toshibas and went straight to the 2SC5200 & 2SA1943 as they are used in great amps such as the AKSA55N+, Lifeforce, both of which I have... good enough for me.
I tried the MJL21193 / MJL21194 as well as TIP3055 / TIP2955. I preferred the sound of the TIP devices over the MJL but could only run a low power version. The 5200 / 1943 combo was the best sounding easily.
The use of MJL devices is what started my playing with this amp as the sound was never right and was bettered using the TIP devices, so it became a thorn in my side. It took 4 years only because it was worked on very occasionally.
my Transformer
This is a topic about transformers, but i'll use my own thread.
I have a 42V 250VA transformer and a 35V 320VA transformer. Rod recommends at least 300VA, but I've been running the 42V 250VA transformer without it even getting warm.
What's the point of having a high VA rating if you barely ever reach that power limit? I should be fine with my 42V 250VA transformer right?
Does the 42V have a significantly higher clipping threshold than the 35V?
Thanks
This is a topic about transformers, but i'll use my own thread.
I have a 42V 250VA transformer and a 35V 320VA transformer. Rod recommends at least 300VA, but I've been running the 42V 250VA transformer without it even getting warm.
What's the point of having a high VA rating if you barely ever reach that power limit? I should be fine with my 42V 250VA transformer right?
Does the 42V have a significantly higher clipping threshold than the 35V?
Thanks
my P3....
was made with my own pcb ..... rods pcb might be good or may be the best but doesnt look symmetric ....
i like this very much in my construction .....
there i will add that once i constructed a special made P3 size
22 cm long and wide 3cm to fit inside a surround speaker .... double sided of course ....
well i constructed everything the same like the normal version of P3 i made but amplifier didnt sound the same ....
so pcb and ground routing is very importand i thing ........
mine is not constructed with the same exotic material you use but is made with original 2SA1302-3281 since i have them original .....
as about tips ....
the only thing i have to add is the 100mf capacitors ....are crirtical and its also critical to be next to the transistors
here is a photo
was made with my own pcb ..... rods pcb might be good or may be the best but doesnt look symmetric ....
i like this very much in my construction .....
there i will add that once i constructed a special made P3 size
22 cm long and wide 3cm to fit inside a surround speaker .... double sided of course ....
well i constructed everything the same like the normal version of P3 i made but amplifier didnt sound the same ....
so pcb and ground routing is very importand i thing ........
mine is not constructed with the same exotic material you use but is made with original 2SA1302-3281 since i have them original .....
as about tips ....
the only thing i have to add is the 100mf capacitors ....are crirtical and its also critical to be next to the transistors
here is a photo
An externally hosted image should be here but it was not working when we last tested it.
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