p2p or PCB

soundNERD · 19th January 2005, 01:58 AM

I have always wondered what you guys thought about the differences between p2p and PCB built chipamps.

I usually use PCBs, but for my latest 3875 amp (actually first 3875 amp, and turned out to be my best ever), I really didn't feel like making boards, so I thought I would try p2p wiring. Yes it doesn't look as nice, but I almost think it sounds better due to less resistance because all parts are soldered directly to the pins.

I have also put electrical tape along most connections that have any possibility of touching.

Are there any disadvantages besides looks and chance of parts touching when using p2p?

And, what are your opinions on each method?

thomas997 · 19th January 2005, 04:17 AM

Add perf board in there, my favorite

tmblack · 19th January 2005, 05:51 PM

P2P need no boards to buy but time consuming and pins can be bent or damaged with accident!

PCB design is fixed so changes are more difficult.

Should show no difference is sound if thick traces are used where needed.

Tom

demogorgon · 22nd January 2005, 12:53 AM

I prefer a slight mix of the two, as with most things, to combine the positive's of both.
I buildt the lm4700 on a pice of veroboard with the feedback resistor and caps (470uf) on the pins, and the rest on board. it makes for short paths, a very compact design, half way good look and easy\logical layout. to bad one if the ic's blew up, i was looking forwar to hearing it. mono kind of suck, and dont make for comparasing against a stereo setup, but it did show promising resoults. i actually think the lm4700 can be better sounding than the lm3886.

soundNERD · 23rd January 2005, 01:49 AM

OK, what I've decided to do was to build the identical circuit on a PCB. Its the same, except I changed a couple of resistor values and brands because I had no more of the others. The feedback resistor (a 51K NTE 1% Metal Film) stayed the same, but Ri (on the datsheet, don't know what its called, but it goes from negative input to ground changed. I had I think a 2k cheap metal film resistor, and I used a 1.8k Allen Bradley carbon resistor, and I used that same 1.8K resistor for the input resistor.

I made a PCB with one chip on the left side and one on the right. This means I have 2 heatsinks on it instead of one. They are the same heatsinks though.

The first thing I noticed was that it ran much cooler. Even when cranked, it barely got warm, neither the chips or the heatsinks. The P2P amp got unbelieveably hot with anything going through it. It used one heatsink for both chips, though.

I'm going to have to comment on the sound difference later, because right now I'm using a 20 dollar cd/mp3 cd player. Again, comparing to my kenwood 100x2 amp, this can push an undistorted signal enough to cause the speakers themselves to distort, while the kenwood is distorting far before this point. And it's half the power!

pics coming too...

EDIT: Almost forgot to mention - The power supply was the same one. In fact, I just hooked them both up to the same supply, but only ran a signal and had speakers connected to the new one.

soundNERD · 25th January 2005, 01:34 AM

OK heres the P2P amp. It doens't look too nice, and I'm worried that using it to drive expensive speakers is too much of a risk.

Sorry about the picture quality, my digital camera doesnt like close pics.

soundNERD · 25th January 2005, 01:39 AM

And here is the amp built onto a PCB.The top connector is power, and the bottom center one is input and the other 2 are speaker connections

soundNERD · 25th January 2005, 01:45 AM

Finally, the entire thing built into the box.

Now, the sound. I'm much more impressed with it than the P2P amp, though they both sound great. I also like how it runs cooler (possibly the messy wires of the p2p amp was causing slight oscillation????). The only thing is somehow a transformer from a logitech z680 (500W) system isn't enough! When the bass hits, and it distorts, the LED dims, either meaning the voltage is just going down, or its running out of current. Either way, tons of bass is not important at all. All that matters is quality. I could always increase the capacitance and get a little more out of it, but doing that would reduce the clarity. I currently have 2 2200uf 35VDC caps on each rail, and, as i've said, I'm pretty impressed.

homer09 · 25th January 2005, 01:45 AM

It will be interesting to see your results soundnerd, you definitely be the first to make a direct comparison between the two. But i think by using different resistors, you are spoiling the comparison.

If you really cant match enough parts, try listening a bit, then trading different parts.

homer09 · 25th January 2005, 01:51 AM

Whats the VA rating on that transfo? Seems pretty big from the pic...

19th January 2005, 01:58 AM	#1
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	p2p or PCB I have always wondered what you guys thought about the differences between p2p and PCB built chipamps. I usually use PCBs, but for my latest 3875 amp (actually first 3875 amp, and turned out to be my best ever), I really didn't feel like making boards, so I thought I would try p2p wiring. Yes it doesn't look as nice, but I almost think it sounds better due to less resistance because all parts are soldered directly to the pins. I have also put electrical tape along most connections that have any possibility of touching. Are there any disadvantages besides looks and chance of parts touching when using p2p? And, what are your opinions on each method?

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19th January 2005, 04:17 AM	#2
thomas997 diyAudio Member Join Date: Feb 2004 Location: Vancouver	Add perf board in there, my favorite

19th January 2005, 05:51 PM	#3
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	P2P need no boards to buy but time consuming and pins can be bent or damaged with accident! PCB design is fixed so changes are more difficult. Should show no difference is sound if thick traces are used where needed. Tom

22nd January 2005, 12:53 AM	#4
demogorgon diyAudio Member Join Date: Jul 2004 Location: Behind you.	I prefer a slight mix of the two, as with most things, to combine the positive's of both. I buildt the lm4700 on a pice of veroboard with the feedback resistor and caps (470uf) on the pins, and the rest on board. it makes for short paths, a very compact design, half way good look and easy\logical layout. to bad one if the ic's blew up, i was looking forwar to hearing it. mono kind of suck, and dont make for comparasing against a stereo setup, but it did show promising resoults. i actually think the lm4700 can be better sounding than the lm3886.

23rd January 2005, 01:49 AM	#5
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	OK, what I've decided to do was to build the identical circuit on a PCB. Its the same, except I changed a couple of resistor values and brands because I had no more of the others. The feedback resistor (a 51K NTE 1% Metal Film) stayed the same, but Ri (on the datsheet, don't know what its called, but it goes from negative input to ground changed. I had I think a 2k cheap metal film resistor, and I used a 1.8k Allen Bradley carbon resistor, and I used that same 1.8K resistor for the input resistor. I made a PCB with one chip on the left side and one on the right. This means I have 2 heatsinks on it instead of one. They are the same heatsinks though. The first thing I noticed was that it ran much cooler. Even when cranked, it barely got warm, neither the chips or the heatsinks. The P2P amp got unbelieveably hot with anything going through it. It used one heatsink for both chips, though. I'm going to have to comment on the sound difference later, because right now I'm using a 20 dollar cd/mp3 cd player. Again, comparing to my kenwood 100x2 amp, this can push an undistorted signal enough to cause the speakers themselves to distort, while the kenwood is distorting far before this point. And it's half the power! pics coming too... EDIT: Almost forgot to mention - The power supply was the same one. In fact, I just hooked them both up to the same supply, but only ran a signal and had speakers connected to the new one.

25th January 2005, 01:45 AM	#9
homer09 diyAudio Member Join Date: Jan 2004 Location: Montreal	It will be interesting to see your results soundnerd, you definitely be the first to make a direct comparison between the two. But i think by using different resistors, you are spoiling the comparison. If you really cant match enough parts, try listening a bit, then trading different parts.

25th January 2005, 01:51 AM	#10
homer09 diyAudio Member Join Date: Jan 2004 Location: Montreal	Whats the VA rating on that transfo? Seems pretty big from the pic...

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