Amp3 capacitance

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Posted - 08 Aug 2005 : 12:41:42 Show Profile Email Poster Edit Topic Reply with Quote Delete Topic
I have just finshed my Amp3, will post picture later. First just to say that it sounds excellent, certainly better than my heavily modded Sonic Impact. The Si sounded great but the sound stage while very wide wasnt very deep, also i found that the large polypropelene input caps seemd to picke up some knind of noise fromt eh amps itself. Even with stock panny FC input the Amp3 sounds better IMHO.

My question is this, I use a 5 amp SMPS for the power, and currently use an array of 18 * 1000 uf caps in the amp3 between the power switch and the power input on the board. I did this since i had an large number of these cheap BC 037 series caps. I now think that the amps 3 deserve some better power supply caps and was wondering if there was any advantgae to what i have done or wether it might be an idea to just buy some larger value caps. Or indeed a range of caps to power the amp, i was think somthing like either 18* 1200uf 16v panasonic FC and then maybe some 470uf starget on the amp board or 3* 4700uf panasonic fc then 6* 1200 panasonic fc. And maybe the same staget on the amp board, or maybe a 470uf fc again.

Any idea?

Would a stagerring or caps size be better than my current array of 1000uf caps that the question i guess.

The other thing i was thinking is should i also move to 25v caps since i maybe try and tweak teh SMPS upto 14v in the future i would imagine this would be too tighter for the 16v value caps/

I expect that a bank of FCs will give significantly better (lower) ESR than the BCs. On the pcb I'd much rather use FCs or Rubycon ZL/ZA than Stargets.

Regarding the noise, I had experienced that too, but that was before installation into a case, when the gnd for the power section was floating (temporary battery supply). The moment the linear power supply was connected and the pcb solidly grounded, I have no further induced noise.

Yes, the Amp3 sounds great, doesn't it??
I finished my AMP3 last week. I didn't test it with "high quality gear" yet but I must say I was suprised by the quality of the sound with my Mission 760i (89 dB/w, 6 ohm) speakers. The sound is very clear and bass impact is impressive.

I used 4 x 8300 uF 16 V Panasonic FC caps. I've played it with a 12 V 6 ah battery and 12 V transformer (with rectification naturally). PS voltage is too high with 12V transformer but the amp didn't seem to care.

I placed the amp in an aluminum box (3,5*8*12 cm, ~2 mm thick). The amp runs totally cool.

Atleast for travel use this is definitely a great amp. Low power consumption, small size and good sound.
Interesting stuff all around. Yes the amp does sound excellent with realitively normal caps and i hope with some FC's it will be better. I would be very careful about using a 12v transformer since you would be running the amp at close to 16v, that quite a bit over the maximum rating. I doubt it will last long. Maybe use a stage of regulation to drop it down?

Nuuk said he had uses a 'snubberised' cap after a smps, anyone else tried a snubber setup?

I forgot to say that I had extra diodes in power supply to prevent reverse polarity in case that I misconnect the amplifier to a battery. Those diodes drop the voltage a little bit. Maybe just enough

Secondly, I used the transformer only for testing. You are definitely right, the voltage is too high. Even 10 V transformer is a bit risky. A 9 V transformer would be my choise.

I intend to use the amp only with 12 V battery.
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