Howdy folks, I am trying to massage a wetter reverb sound out of a Peavey Delta Blues. The reverb is driven and recovered by a 4558 opamp. I have decreased nfb in both the driving and recovery stages to increase gain and gotten a small yet noticeable improvement. I don't want to increase the recovery-stage gain any more for risk of adding increased noise and increased sensitivity to mechanical feedback.
I calculate that the issue is drive-related and that the 4558 is not capable of supplying enough current to saturate the input coil of the reverb tank. Is there a drop in(pin-compatible) replacement for the TI RC4558 that would supply more current to drive the tank? I don't really want to perform major surgery on the amp(it's one of those folded-pcb models designed by satan himself) but I am curious if there is a better chip for this application that would drop in the socket and go. I have a schematic available if anybody wants to help me tackle this problem. Thanx!
I calculate that the issue is drive-related and that the 4558 is not capable of supplying enough current to saturate the input coil of the reverb tank. Is there a drop in(pin-compatible) replacement for the TI RC4558 that would supply more current to drive the tank? I don't really want to perform major surgery on the amp(it's one of those folded-pcb models designed by satan himself) but I am curious if there is a better chip for this application that would drop in the socket and go. I have a schematic available if anybody wants to help me tackle this problem. Thanx!
You could try something like an NE5532 or LM4562 which has better drive ability than a 4558. They should be a drop in replacement.
Thanks. Newark has LM4562 in the dip8 package for $1.65 each. I'll order up a couple here in the next few days.
I see that the 4558 doesn't like to drive a load under 10k and the tank has a nominal 1khz impedance of 600 ohms. No wonder it was thin and weak sounding. The LM4562 has a rated 2k load impedance, should be MUCH better suited to this application.
I appreciate the tip.
MJB
I see that the 4558 doesn't like to drive a load under 10k and the tank has a nominal 1khz impedance of 600 ohms. No wonder it was thin and weak sounding. The LM4562 has a rated 2k load impedance, should be MUCH better suited to this application.
I appreciate the tip.
MJB
Well the 4562 will fully drive loads down to 600 ohm... and actually there is another great high drive opamp, the NJM4560 which used to be really common,
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Thanks again. I'm relatively new to the world of IC circuitry, though I am fairly competent when it comes to tube amps. I posted another thread with an IC question, this time regarding output chips. Would you mind taking a look? Here's the link:
http://www.diyaudio.com/forums/soli...-pa-chip-conversion-question.html#post3871834
http://www.diyaudio.com/forums/soli...-pa-chip-conversion-question.html#post3871834
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OK 🙂 Just had a quick look. Now chip power amps aren't really my thing but I know many swear by them and they are undoubtedly very competent performers.
How about something like a TDA7293 design. These chips can be paralled too for even higher output but , with a -/+35 volt rail you shouldn't have any worries because that's a good voltage to work with and chips like a single TDA7293 or an LM3886 should reach their full performance potential.
I know there are lots of PCB's and kits available from the usual suspects 😀 but I haven't used any. Try a search for the parallel TDA7293 design. The circuit is in the data sheet, I'm sure boards must be available.
How about something like a TDA7293 design. These chips can be paralled too for even higher output but , with a -/+35 volt rail you shouldn't have any worries because that's a good voltage to work with and chips like a single TDA7293 or an LM3886 should reach their full performance potential.
I know there are lots of PCB's and kits available from the usual suspects 😀 but I haven't used any. Try a search for the parallel TDA7293 design. The circuit is in the data sheet, I'm sure boards must be available.
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