PCB for simple OP-preamp

kmj · 1st August 2005, 01:05 AM

to keep it short, will this do for a pcb-layout? I have never made a pcb before but i had some time over and parts that were of no use at the moment

the ground from the pot is at the same place as the inputground.

tobias_svensk · 1st August 2005, 04:04 AM

Hello kmj

Looks good I think, you could move your 0.1uF on the V+ rail I guess. Put it between the Output L/R resistors and move your Output ground hole a little bit.

Roushon · 1st August 2005, 07:15 AM

it might be a good idea to make and connect the input ground to the power ground by a thin track, otherwise distortion may get into the input signal.

kmj · 1st August 2005, 07:31 PM

Roushon
So just make the rail between the 0,1uF MKP cap and the inputground thinner then.

tobias_svensk
Just move the cap to the other side of the electrolyte then.
(those yellow things next to the out R and out L text are two VERY big capacitors )

I'll have to test your advice, i put it together this afternoon and it works. However, i get a loud background buzz, like a bad radioreception.

Roushon · 2nd August 2005, 09:39 AM

make the whole vertical track on the left hand side of the pcb thin.

kmj · 2nd August 2005, 06:30 PM

Will do.
The buzzing is still there and i stumbled on a strange problem.

It still works with the NE5532 op, buzz and all, but not with opa2604.
If i shut the pre down and change op the fuses melt. strange since the opa2604 only need about 5-6mA and the fuse is rated at 125mA-slow and the supply is a regulated 12V.

one shouldn't have any prblem with something as simple as this....

veteran · 8th August 2005, 09:07 PM

Several months ago I also designed pcb for single op-amp preamplifier

I enclose several pictures. There is also dedicated symmetrical power supply based on LT317/337 regulators.

veteran · 8th August 2005, 09:08 PM

Power supply pcb...

veteran · 8th August 2005, 09:10 PM

Bottom side of preamplifier pcb.

1st August 2005, 07:15 AM	#3
Roushon diyAudio Member Join Date: Sep 2004 Location: Mumbai (Bombay)	it might be a good idea to make and connect the input ground to the power ground by a thin track, otherwise distortion may get into the input signal. __________________ S. Roushon

2nd August 2005, 09:39 AM	#5
Roushon diyAudio Member Join Date: Sep 2004 Location: Mumbai (Bombay)	make the whole vertical track on the left hand side of the pcb thin. __________________ S. Roushon

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1st August 2005, 04:04 AM	#2
tobias_svensk diyAudio Member Join Date: Jan 2004 Location: Hudiksvall	Hello kmj Looks good I think, you could move your 0.1uF on the V+ rail I guess. Put it between the Output L/R resistors and move your Output ground hole a little bit.

1st August 2005, 07:31 PM	#4
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	Roushon So just make the rail between the 0,1uF MKP cap and the inputground thinner then. tobias_svensk Just move the cap to the other side of the electrolyte then. (those yellow things next to the out R and out L text are two VERY big capacitors ) I'll have to test your advice, i put it together this afternoon and it works. However, i get a loud background buzz, like a bad radioreception.

2nd August 2005, 06:30 PM	#6
kmj diyAudio Member Join Date: Feb 2004 Location: Falkenberg	Will do. The buzzing is still there and i stumbled on a strange problem. It still works with the NE5532 op, buzz and all, but not with opa2604. If i shut the pre down and change op the fuses melt. strange since the opa2604 only need about 5-6mA and the fuse is rated at 125mA-slow and the supply is a regulated 12V. one shouldn't have any prblem with something as simple as this....