Hello, I am considering rebuilding an old Marlboro PA head with a bad output section. Schematic is unavailable and there is a problem in the output/drive section that I can not track down. In order to save some frustration, I am considering rebuilding the output section with IC outputs. The PA has a pretty hefty transformer yielding +/-35v rails(approx) and the preamp/control board functions just fine. I'm very competent with tube amplifiers but I'm a bit of a noob when it comes to solid-state. Would it be feasible to replace the output/drive section with IC's and how difficult of a conversion do you think it would be?
The amp was originally 100w/channel with 2 discrete output channels. I would like at least this much power available, and since it is a PA system I need an output with some headroom that can handle some pretty big transients without distorting badly or going up in smoke. What would you guys recommend for a decent output chip for this application? PA will be used for vocals primarily with maybe an acoustic guitar from time to time, so I don't need an ultra-low hz response. Just need something that can keep up with drums and guitars in a live rehearsal setting.
I would like to keep costs pretty low, so I'm also looking for a good value in selecting output chips. Simplicity is also a plus, as I have at least 15 projects in various stages of completion at any given time.
Any information or guidance would be much appreciated. Thanx!
The amp was originally 100w/channel with 2 discrete output channels. I would like at least this much power available, and since it is a PA system I need an output with some headroom that can handle some pretty big transients without distorting badly or going up in smoke. What would you guys recommend for a decent output chip for this application? PA will be used for vocals primarily with maybe an acoustic guitar from time to time, so I don't need an ultra-low hz response. Just need something that can keep up with drums and guitars in a live rehearsal setting.
I would like to keep costs pretty low, so I'm also looking for a good value in selecting output chips. Simplicity is also a plus, as I have at least 15 projects in various stages of completion at any given time.
Any information or guidance would be much appreciated. Thanx!
Doesn't get any simpler than that I suppose. I'm located in the USA-- can you think of any similar/equivalent parts that would be stocked by major US distributors?
I was thinking more along the lines of parallel LM3875. There is much information on this site re: LM3875 DIY amps. Could you maybe point me in the direction of a good thread on paralleled LM3875 output sections? The PSU is already built though I may upgrade the main filter caps(I have a pair of Sprague powerlytic 50kuf 50vdc cans that will fit inside the cavernous enclosure.) Remember, I'm a noob when it comes to solid-state but if I have a good schematic I can build it. I'm leaning towards the LM3875 for the sake of simplicity and ready availability of parts.
Have you checked out the chip-amp forum here yet? There are several threads there that discuss similar ideas to your own with various bridge/parallel combinations of many suitable chip amps. Chip Amps - diyAudio
Yes, I've read a few of the threads. It's slow going, as much of the terminology is rather foreign to me. I guess I was hopeful that all of the information I need would be neatly compiled in one place. I'll keep reading.
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