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I've got to replace the output tubes on my integrated amp (cr development romulus V3) but I'm still waiting for the bias instructions as the dealer/manufacturer are unable/slow to provide that info. So my question is: Can I run the new tubes (which are Svetlana 6l6gc's - old tubes were Chelmer/Sovtek 6l6wgc/5881) without rebiasing the amp for some time (until I get the bias instructions) or would that be harmfull to the amp or the tubes?Thanks!
Follow Ups:
The 6L6 and 5881 are made differently and have sonic differences:Tesla Mfg JJ
6l6GC 35-45 ma,tends to be warm, great attack; very low microphonics;
low noise; but some detail loss at higher bias(48-50ma).Shuguang
5881 35-50 ma, better at 50 ma, little microphonic; more noise; thin
sounding at low bias(35-40ma)should be biased on the high side.Tubes vary greatly in fidelity due to the materials used and directly in respsect to the bias level.
For best over all sound, try the 6L6GC by Philips...
To be safe, I'd have to say no. If the amp is autobias via cathode bias, you could. If it has a negative voltage applied to the grids then absolutely not. If you got a schematic w/the amp, check if it shows a negative bias supply (single diode, low voltage electrolytic cap, resistor connected to control grid) This is "fixed" adjustable control grid bias and MUST be adusted for new tubes. What brand and model amplifier is it?
Thanks for your reply. The amp is of the "fixed bias" variety. It is a CR Development Romulus V3 (PP with four 6l6gc output tubes). It provides DIN sockets on the bottom to measure the bias current for each pair of output tubes but I don't now which pins to use for the measurement.
G,The 6L6WGB/5881 probably idles at a different setting than those Svetlana 6L6GC's.
Running the Svet's without biasing, the idle is probably set a bit too low (over-biased). Should lead to a cold, sterile tone in a tube which already is kinda cold & sterile.
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