ben. Posted November 24, 2004 Share Posted November 24, 2004 Who has suggestions for this tube type? I just bought a Music Man HD 130 bass/guitar amp, and am looking into good replacements. Seller has some modern stuff in there, IIRC. KT77 is a premium sub, right? Also, can anyone tell me what's going on when this amp is switched to 65W rather than 130W? Triode operation? The schematic is a mess to me. That's what I get for messing with sand, I suppose... Link to schem... http://www.ernieball.com/mmonline/techinfo/old_amps/2100-130.zip or http://www.ernieball.com/mmonline/techinfo/old_amps/2100-130.pdf Quote Link to comment Share on other sites More sharing options...
Guy Landau Posted November 24, 2004 Share Posted November 24, 2004 EL34 suggestions: (for audio) 1. Amperex DD getter 2. Mullard XF1 code, "big base" 3. KT77 4. RCA/GE 6CA7 considered excellent for guitar amps. Not as nice as the above 3 - has powerful presention but not as sweet. Quote Link to comment Share on other sites More sharing options...
Painful Reality Posted November 24, 2004 Share Posted November 24, 2004 ---------------- On 11/24/2004 1:39:10 AM bclarke421 wrote: Also, can anyone tell me what's going on when this amp is switched to 65W rather than 130W? Triode operation? The schematic is a mess to me. That's what I get for messing with sand, I suppose... Link to schem... http://www.ernieball.com/mmonline/techinfo/old_amps/2100-130.zip or http://www.ernieball.com/mmonline/techinfo/old_amps/2100-130.pdf ---------------- I don't see any switch that influence the operation mode (i.e. triode or pentode). OTOH, in the last schematic of the pdf file, there is a switch that will drop the HT voltage. Take a look at the hi-low switch on the HT secondary of the power transformer. My guess is that this will reduce the power by lowering the operation point of the power tube. Quote Link to comment Share on other sites More sharing options...
ben. Posted November 25, 2004 Author Share Posted November 25, 2004 Thanks Guy & Jeff. I'll keep an eye out for those tubes, Guy. Jeff, that's kind of what I was thinking based on what little info I had seen. I had come across some comments about tube life being improved at the lower power settings, so that makes sense. This move couldn't have been timed better. The B-15 was acting strangely last night at a gig. I push it right to its volume limits, as I have not had a chance to acquire the Bill Fitzmaurice DR horn rig (250a/Tuba24) that I've been looking into. Well, the OP tubes were giving a bright blue glow that would alternate between the two tubes. I don't know if they were doing this consistently, as I was watching a mixer and monitor system at the same time. It made it through the night OK, and didn't seem to be running hot or anything. I'm guessing the tubes are just getting there with the abuse I'm putting it through. Thankfully, I've put the EH that it came with back in due to cage fit issues. I don't want to be burning through the 350B I had in there, if that's even what's up. Guy-got your mail, thanks. Did it bounce yet? Quote Link to comment Share on other sites More sharing options...
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