Hey all! Was excited to recently find one of these old MM HD 130 heads locally at a good price. I have wanted one for a while to compare to my V4B reissue for practice/small gig duty. I play in an indie rock band that can get quite loud with two Twin Reverbs and a very forceful drummer, and the V4 just baaarely runs out of headroom/muscle in most of the scenarios that I try to use it in. I have heard the 130s are all about being loud and clean which sounds like the ticket.
Anyway, the one I found is an "HD-130 Reverb" model that was originally aimed at guitarists but has an identical power stage to the non-Reverb model as I understand. It has EL-34s installed. I tried to use it at practice the other night and followed the trick that I've heard repeated for these amps of diming the master volume and using the gain knob to control the overall volume via the preamp, in order to avoid the nasty preamp distortion (which I can confirm sounds quite trash.) With the master at 10 and the gain knob right around 2-3 I had more than enough volume, but I was getting a fart-y, strangely compressed sounding distortion when I dug into notes a little bit. I tested it afterward with my passive MIJ Mustang bass, no pedals, and was still able to get this strange distortion just from playing heavily at a quite low gain. It does *not* sound like the bad preamp distortion, it's more like a "running out of headroom with your cab/speakers" sort of sound even though I know I'm not anywhere near the limit of the amp or the cab.
I am going to have it benched by my tech as soon as I can but in the interest of trying to better phrase my observations to him, I was wondering if anyone here has experienced this on the 130. I am fairly new to tube amps and I feel like it could be something as simple as needing a re-bias, or as complex as a full cap job or similar since it is a half-century old amp at this point.
