....which is typically nullified if not reversed in a cathode bias amp.Originally posted by dzeitlin
GT's ratings are an indicater of how quickly the tubes distort (1 being the quickest).
...which still holds true with cathode biased amps.Originally posted by dzeitlin
GT's ratings are an indicater of how quickly the tubes distort (1 being the quickest).
Not necessarilly. The GT numbers assume that the tubes are going to be biased correctly. In cathode biased amps you never know whether they'll be biased correctly or not.Originally posted by theelectic
...which still holds true with cathode biased amps.
Originally posted by Blue Strat
....A GT 5 rating is usually a safe bet.
I'm not sure you'll ever get the amp totally clean but a lower rated pair of power tubes could help. Have you tried a 5751 in the first gain stage?Originally posted by mbruffey
OK, Thanks all, especially Mike, for your replies!
Now why am I asking the question? I have a cathode biased amp--its a Carr Rambler--that seems overwhelmed, even at LOW volumes (like 9'oclock on the amp vol), when I have amp settings low on the middle knob and the guitar rolled back just where treble kicks in. It's really noticeable with the rhythm pickup. Sounds like I have a (light) fuzz box anytime I play more than a single note.
I play Chet style, nice and clean and lo volume--no thrash or anything like that. Primary guitar is a Gibson CG, but I have others with P-90s, etc. All behave similarly.
After trying all kinds of different pre-amp tube substitutions and a different speaker, I can't seem to get rid of the problem. Maybe all Carr Ramblers just sound this way in these circumstances.
I'm left, perhaps, with output tube options. The originals, in the amp when I recvd it used, were Ruby Svets. Just a couple weeks ago I bought new TAD6L6WGC's--everybody is raving about them, you know. Because I had not played the amp a lot before installing the TADs, it was then that I first noticed this distortion issue. Since then, I've A/B'd both sets of output tubes, noting that both produce the undesired distortion under the conditions I've described above.
Since these tubes are rated for PC, I noted that one set has PC:39 (Svets) and the other PC:43 (TADs). [TC was dramaticallly different between the two sets, but I'm not concerned about that, yet . . . .]
Anyway, I'm wondering if I should try a set of tubes with a PC of about 25 or something, just to see if that would make a difference.
Yes? No? Maybe?
Thanks, Mark
Yes, I did try a JG-5751-WA in V1 with little noticeable difference. The Carr has a fancy new technology solid state rectifier. You could read about it at carramps.com or in one of the reviews linked at his site. Thanks, MarkOriginally posted by Blue Strat
I'm not sure you'll ever get the amp totally clean but a lower rated pair of power tubes could help. Have you tried a 5751 in the first gain stage?
Does that amp use a tube rectifier? If so, which one? Switching to a higher rated rectifier could help as well.
Did you try it in V2 as well? I forget how the preamp is laid out in that amp, but it may make more of a difference there. I had some noise in my Slant6V that drove me nuts, until I discovered that it was the power at my place that was the culprit. I plugged it in at my folks house and it was quiet. Have you tried plugging it in somewhere else?Originally posted by mbruffey
Yes, I did try a JG-5751-WA in V1 with little noticeable difference. The Carr has a fancy new technology solid state rectifier. You could read about it at carramps.com or in one of the reviews linked at his site. Thanks, Mark
Well, V2 is all reverb stuff, and I think I ran the circuit with that tube out completely, making no difference in the problem.Originally posted by Brion
Did you try it in V2 as well? I forget how the preamp is laid out in that amp, but it may make more of a difference there. I had some noise in my Slant6V that drove me nuts, until I discovered that it was the power at my place that was the culprit. I plugged it in at my folks house and it was quiet. Have you tried plugging it in somewhere else?
One day my mains were low, about 108 volts, but on the next day, they were at 118-120 and I still had the problem. Taking the amp to another location is about the only thing I haven't actually tried, mostly because the mains tested normal when I was still having the problem. But that does not preclude other line issues, I suppose.Originally posted by Brion
I had some noise in my Slant6V that drove me nuts, until I discovered that it was the power at my place that was the culprit. I plugged it in at my folks house and it was quiet. Have you tried plugging it in somewhere else?