| Author | Message | ||
     David Good (daveg62) Username: daveg62 Registered: 07-2006 |
Does anyone know where to buy these at? I did a complete cap replacement and new tubes in my HD130 head and it still sounds bad. I'd like to try replacing these next but can't seem to find them anywhere. Is there a replacement that will work? | ||
| Reed Ohrbom (reedmoh) Username: reedmoh Registered: 06-2006 |
Dave; A few questions to help me understand my HD130 a little better. 1) Does your amp have the 12AX7 Phase Inverter, or SS? 2) I assume a LM307H is a chip. What function does it have, i.e. what part of the circuit is it in? How did you devise that this chip might be suspect? Thanks for an explanation; I'm just learning about schematics and electronic components. | ||
| David Good (daveg62) Username: daveg62 Registered: 07-2006 |
Reed, I am by no means an electronic tech. I am actually an electrician by trade. I have learned everything about this amp by reading through the posts on this board. I did manage to do a cap replacement and I think I did a good job on that thanks to all the tips from this web-site. I wouldn't doubt that there could be something else wrong with this amp, but before I take it to someone I thought I could try replacing the LM307's since they are very easy to remove and install. From what I understand they are a part of the pre-amp circuit and they would affect your sound much like a pre-amp tube would do in a tube amp. I'm sure somone on this board could explain it better than I could. Yes my amp has the 12ax7 Phase inverter. My serial number is 500 so I think I have one of the early models. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Check the listing under new opamps for bass amp or something like that. Somebody had a few they were willing to sell. I think his name is billups. | ||
| David Good (daveg62) Username: daveg62 Registered: 07-2006 |
Just an update on my amp. I did manage to find replacement lm307's from a member here on the forums and replacing them has definately helped bring back the sound. So far I have replaced all the electrolytic caps, the 600v .047 caps with orange drops, a new set of JJ tubes and now the lm307's. The amp is very quiet and the preamp section is very useable again. Thanks to everyone for all the help here on this forum. I would have never known how to do any of this without the experts sharing their knowledge on this great forum.  | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
I hope you re-biased the amp after the changes. Replacement of caps and tubes is going to alter ALL of the critical viltages downstream. JJ's DO work good in the MM's as well as in my Fender amps. I didn't defect but I AM playing through a 1971 bassman head right now that's had a lot done to it. I got it right(it needed THINGS) and I can lift it and right now, lifting is a little difficult. As Arnold used to say, "I'll be back". | ||
| David Good (daveg62) Username: daveg62 Registered: 07-2006 |
Mike, I did re-bias after changing tubes and also again after changing the caps out. The only thing I didn't do was re-bias this last time after replacing the LM307's. I guess it wouldn't hurt to do so but do you think it is necessary? | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Not after doing the lm307's-they're just in the gain stage. |