| Author | Message | ||
     Langley |
I have a transitional 210-65 with Solid State driver. It's in showroom condition, and sounds wonderful. My tech has recommended conversion of the output amp to cathode bias. Has anyone done this? If so what experience has this generated? (Sounds good, sounds bad, caused problems, etc.) What components were changed/removed/added? Thanks. | ||
| TERRY |
IF THIS AMP SOUNDS BEAUTIFUL AS I'M SURE IT DOES, I WOULD LEAVE THE BIAS ALONE. EVIDENTLY YOUR REPAIR TECH. DOES NOT UNDERSTAND HOW THE BIAS CIRCUIT WORKS IN THIS AMP. GO TO THE TOP POSTING AND BIAS THE AMP THE WAY MUSICMAN DESIGNED IT. IT WILL LAST ANOTHER 20 YEARS. IF YOU WANT A MARSHALL, THEN THIS MUSICMAN IS NOT WHAT YOU ARE LOOKING FOR. | ||
| Langley |
My tech is Dennis Kaeger. | ||
| John D. |
What exactly is coverting the output amp to cathod bias do/mean? Going back to a tube preamp like the early models? I'm not a techie, so I don't understand your question. | ||
| Steve Kennedy |
An amp wired in the "grid bias" configuration requires the bias to be set by adjustment. The later Music Man amps are wired this way. An output stage wired in a "cathode bias" arrangement has a sort of "self-bias" effect and no manual bias adjustment is required. Some early Music Man models were wired in this fashion. These two methods result in two slightly different sounding output stages. Steve (Message edited by admin on February 06, 2003) | ||
| William Michel (bill) Username: bill Registered: 12-2006 |
Nice thread. I posted earlier this week about a sudden desire to hear more 'treble' chime, or whatever it was I felt I'd been missing. Always I am thinking of the Fuchs phenomenon, and how I don't wish to go there. Terry's capped message is another thing I'd been reflecting on, even before I'd seen it. I have some 12AX7 PI mm amps. They are such a treat, to look at and to fire up. At the moment I have done no mods, not even a jeweled lens replacement. I guess this goes out to the specialists out there...class B is neat, because it saves tube wear and is very efficient esp when compared to class A amps.... It is said that the crossover distortion lends an aggressive sound. Is my amp in need of a go through?, though there's no spits nor sparks...it seems to lack high end chime. I have no trouble dialing in a little distortion. Just turn the master all the way as Leo suggested, and approach final volume with the line volume. That the amp makes no fuss at peak power convinces me it's all right. Yet, I want some extra element in the sound. Therefore....Terry? Could I have blown a transistor or some filter cap, or anything, somewhere and not be aware of it? This amp sounds pretty much like any other 65 watter reverb combo/head, though I've not done a recent side by side. Once a good pair of tubes are in place, I view the chassis as a tube holder. A place where they are comfortable, not to be disturbed. It's just that I am hearing less than I am wanting way up high. Perhaps the tone cap in the old guitars are drifted from where they are supposed to be at, and therefore let in too much low frequencies? Would the tone cap in the guitar trorw away high freqs if drifted? I'm pretty sure my ears are being a fair judge, not affected by hearing loss or white *lies*. Little help is great. Just a tone search. I am inclined to leave my amps alone unless to recondition stock, or do a minor tone mod. These amps make tube screening a breeze. You can change one tube and get such a different sound at crunch, where the shtf. (I've heard tell that you are only hearing the OT in these amps. I don't think so). Most amps have so many tubes that you never can really tell what contribution a switched tube made. Thanks... | ||
| William Michel (bill) Username: bill Registered: 12-2006 |
These amps do extend life, if only because you have got to stay alive 4-5 years to read a new entry! Misspelled 'throw' in above message, sorry. |