ranjam
New member
I just brought home a used dbx 386 from my local music store. I'm thinking clean the pots and tube sockets, tighten up any hardware, and it'll be good to go. Then I get a brilliant idea to put a signal generator through it, and scope it out, checking the waveform and frequency response. Well, channel 1 won't go into the red as easily as channel two . So, I swap tubes between channel 1 and channel 2. Same difference. I don't see any trim pots around the input section. The waveforms looks great, but just quite a bit lower on channel 1 (for exactly the same settings as on channel 2). With a real microphone it appears to be a bit lower as well, but that may be the power of suggestion . Is this tolerance or difference in gain between two channels in the same preamplifier acceptable? I can always return the preamp, but I don't want to look like a worry wart. I can't find any schematic online, so I have no idea what to check other than tubes. Whaddaya think?