I have an old 100W PA amp with spring reverb in it. I want to tap it so I can directly record the output. The amp doesn't have line out or headphone out. I could do the voltage divider mod using resistors, in my case I guess about 33k and 1k on ground. But I'm not sure if using something like non-polar 10Uf cap behind the resistors wouldn't be safer way to go. In my opinion it would stop any power peaks (switches pops etc) or what ever the old amp might produce and protect my mixer. But I think the cap could cut some high end which wouldn't be too good. What do you guys think would be the best way make it safe?
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A cap passes high frequencies and stops DC.
I assume that with 'a cap behind ...' you mean in series with the output to the mixer. That cap does not attenuate highs.
That cap would be transparent to any switching transients so that would not help.
It would help with DC on the output but there is none in an amp with output transformer, and only on a solid state amp when it fails cathastrophically but then you got worse problems.
So, forget the cap, just use the resistive divider and Bob's your uncle.
You may want to use a volume pot instead of the fixed resistors so you can control the level without changing the amp level.
Jan
I assume that with 'a cap behind ...' you mean in series with the output to the mixer. That cap does not attenuate highs.
That cap would be transparent to any switching transients so that would not help.
It would help with DC on the output but there is none in an amp with output transformer, and only on a solid state amp when it fails cathastrophically but then you got worse problems.
So, forget the cap, just use the resistive divider and Bob's your uncle.
You may want to use a volume pot instead of the fixed resistors so you can control the level without changing the amp level.
Jan
A good answer, but since the OP mentions a mixer a balanced output would be beneficial reducing hum.
Speaker/red-----15k--+---XLR2
..............................................1k
..............................................+---XLR1
..............................................1k
Speaker/blk-----15k--+---XLR3
actually would be better to connect to a stereo Jack for the line input, since there might be 48V Phantom voltage on the XLR. wouldn't damage anything thou.
Speaker/red-----15k--+---XLR2
..............................................1k
..............................................+---XLR1
..............................................1k
Speaker/blk-----15k--+---XLR3
actually would be better to connect to a stereo Jack for the line input, since there might be 48V Phantom voltage on the XLR. wouldn't damage anything thou.
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I made the basic divider (without cap) but after some listening, the signal the power transistors just wasn't the same. So I dived in a little deeper and managed to tap the preamp and that works really good. While I was at it I also tapped the reverb tank so now I have two outputs, pre and rev only. So it worked out well. But thanks for help.