About 15 years ago, I bought a nearly mint condition early 70's DC-300A amplifier at a garage sale. I even got the original instruction manual with it. I've used it for a number of applications over the years, including DJ use and home audio use; it's been a dependable and great sounding amp. It was strong enough to easily burn out a pair of 15" Kicker car woofers (I was on a tight budget at the time, and I had to use non-pro speakers). Those poor speakers were smoking! It even had enough power to damage the 4" voice coil on a used 15" Peavey Black Widow speaker I bought later. And I've yet to hear the DC-300A distort! I've never abused the amp, but the original owner was in a local rock band, so who knows how rough he was on the amp.
About 5 years ago, while using it in my home audio system, it began making a raspy "popcorn" sound through the speakers (Allison CD-9 speakers). It only lasted for a few seconds, and I couldn't tell which side it was coming from. A few months later it did it again, and I unhooked the amp and put it away, until now.
I'm interested in using this amp again, and I'm wondering if the noise is due to a bad output transistor? Is this a potentially expensive repair? When I bought it, it had the mono single channel modification done to it already, but it was in stereo mode when the popping sound occurred.
I'd like to know what everyone thinks, and if the amp is repairable. This is one of my favorite pieces of audio equipment, so I'd like to get it running back up to factory specs. The amp still sounds great, but the popping can be unnerving!
For the curious, the rest of my home equipment (I don't do the DJ stuff anymore): Denon 1650 CD player, Electro-Voice MS-820 Monitors, Golden Tube SE-40 Amp, Allison CD-9 speakers, Rotel turntable with Grado cartridge, Yamaha Natural Sound Preamp, Tara Labs cables.