| Author | Message | ||
     Andy Simons (billster) Username: billster Registered: 12-2010 |
Hi Folks I wonder if some of you out there might be able to help me? A little while back I acquired the above amp and, seeing as it was over 30 years old, I took it to a local amp tech for re-tubing and a general overhaul. However, after 2 visits to the repair guy and having various failing components replaced (capacitors, resistors etc.) the amp still exhibits an unpleasant and unmusical distortion when playing notes on the bass strings. I have every faith in the repairman but just wondered if anyone out there with specific Music Man experience might be able to shed some light on a possible causes or causes (failing speakers perhaps?). Also, the amp seems to start breaking up too easy for my liking; gain at 4 or higher and the Hi/Lo switch results in almost no change in output volume or tone and the master volume causes no significant increase in volume in the range 5 to 10 to speak of. Is this normal for these amps? Any comments or suggestions would be greatly appreciated. Thanks | ||
| Bill Traylor (bozzy369) Username: bozzy369 Registered: 02-2008 |
yeah the gain to volume ratio takes a bit of playing with.best way to remember is gain below volume clean ,gain above volume dirty ,I find mine to be pretty clean at equal settings as well.now speakers play a huge part on breakup,if they are too low a wattage,not engineered for certain applications,wrong impedance....ect.hope this might help. | ||
| Andy Simons (billster) Username: billster Registered: 12-2010 |
Thanks Bill, I'll play around with that. Any more more info on this and some of the other points anyone please? | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Check for cross-over distortion. A very common problem in the MM amps with solid state drivers. The output tubes are biased very 'cold' (i.e. low idle current) and if one tube is going into cut-off (so no current is flowing) the result is an annoying ver un-musical distortion. This sort of distortion is very easy to spot on the oscilloscope. Cheers, Lars Verholt |