P3A Power Supply

saurus · 13th August 2002, 12:47 PM

Hello all,

This is my first post, although I have been lurking for some time. I am preparing to build my first amp (a P3A) and I have this question:

I think I want to use separate rectifier/smoothing cap circuits for each of the two channels, but I notice that the power rails for the two individual amps on the P3A board are connected together. Doesn't this defeat the purpose of separate power circuits? Does anyone recommend cutting the board in half, or is this not a significant issue?

JBL · 13th August 2002, 01:09 PM

I really don't think that this will be a problem.

This will not affect chanel separation at all.

tiroth · 13th August 2002, 01:22 PM

I cut my boards in half. This also makes spacing the channels on a heatsink easier.

JoeBob · 13th August 2002, 03:56 PM

If the + and - rails of the two channels are conected together on the PCB then it would be a waste to use two power suplies, afterall they'll be connected together as one after. You could cut the board or break the traces if you really wanted a dual-mono configuration. Or just make one psu for the board to run off of. From what people say the p3a seems like a top notch (I'm planning on building one for my sub) AB amp, so you would probably notice an improvement with the dual-mono setup (especially if you use bigger toroids).

paulb · 13th August 2002, 06:24 PM

Cut the traces. You don't need to cut the board (although you could if it makes your internal layout easier).

saurus · 14th August 2002, 12:35 PM

Thanks, everybody!

annex666 · 27th August 2002, 09:01 PM

I'm currently making an amp based on two P3A boards - one is used for each channel.

Each P3A is split so that they are driven from the same pre-amp signal but the output is connected in a passive bi-wire arrangement to the high and low frequency connectors of my speakers.

My question is how would I earth this amp? The power is by means of two toroids (one for each channel) each having a bridge rectifier and two 4,700uF caps.

Would I lose any of the benefits of dual supplies if I tie the earths together? Also I'm employing a zero-volt-line (see ESP) does this effect how the earth is connected?

Any help would be greatly appreciated.

13th August 2002, 12:47 PM	#1
saurus diyAudio Member Join Date: Aug 2002 Location: West of Boston	P3A Power Supply Hello all, This is my first post, although I have been lurking for some time. I am preparing to build my first amp (a P3A) and I have this question: I think I want to use separate rectifier/smoothing cap circuits for each of the two channels, but I notice that the power rails for the two individual amps on the P3A board are connected together. Doesn't this defeat the purpose of separate power circuits? Does anyone recommend cutting the board in half, or is this not a significant issue?

13th August 2002, 01:09 PM	#2
JBL diyAudio Member Join Date: Aug 2001 Location: Canada, N.-B.	I really don't think that this will be a problem. This will not affect chanel separation at all. __________________ Jonathan Blanchard (J.Bl.) ---Nothing is impossible---

14th August 2002, 12:35 PM	#6
saurus diyAudio Member Join Date: Aug 2002 Location: West of Boston	I'll cut the traces. Thanks, everybody!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Split Voltage Switching Power Supply for Power Amp	vectorplane	Swap Meet	2	23rd April 2011 11:48 PM
LTspice tool for power amp power supply component evaluation	andy_c	Software Tools	2	23rd August 2009 05:10 PM
Can i use a computer power supply to power audio amplifiers?	destroyer X	Solid State	91	25th September 2006 04:36 AM
selling high current power supply for power amps.	ericpeters	Swap Meet	0	14th January 2005 02:21 PM
heater supply (xformer specs are 6.3V 2.5A) as supply for a power LED?	jarthel	Tubes / Valves	10	21st July 2003 01:30 PM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

13th August 2002, 01:22 PM	#3
tiroth diyAudio Member Join Date: Dec 2001 Location: Pittsburgh, PA, USA	I cut my boards in half. This also makes spacing the channels on a heatsink easier.

13th August 2002, 03:56 PM	#4
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	If the + and - rails of the two channels are conected together on the PCB then it would be a waste to use two power suplies, afterall they'll be connected together as one after. You could cut the board or break the traces if you really wanted a dual-mono configuration. Or just make one psu for the board to run off of. From what people say the p3a seems like a top notch (I'm planning on building one for my sub) AB amp, so you would probably notice an improvement with the dual-mono setup (especially if you use bigger toroids).

13th August 2002, 06:24 PM	#5
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	Cut the traces. You don't need to cut the board (although you could if it makes your internal layout easier).

27th August 2002, 09:01 PM	#7
annex666 diyAudio Member Join Date: Jul 2002 Location: England	I'm currently making an amp based on two P3A boards - one is used for each channel. Each P3A is split so that they are driven from the same pre-amp signal but the output is connected in a passive bi-wire arrangement to the high and low frequency connectors of my speakers. My question is how would I earth this amp? The power is by means of two toroids (one for each channel) each having a bridge rectifier and two 4,700uF caps. Would I lose any of the benefits of dual supplies if I tie the earths together? Also I'm employing a zero-volt-line (see ESP) does this effect how the earth is connected? Any help would be greatly appreciated.

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read