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hi. my question is ,whats the right bias for the kt88 tubes? my amp came with 6550 tube and the bias for them is 100Mamp,the manual says i can use the kt 88 to but nothing about the bias....is it same for all amps...?thanks
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so,what should i do ? i cant keep biasing and trying.it will drive me crazy...my amp is cary cad50 mono blocks.......
I currently use KT-88's in my SLAM 100's. The bias setting for new SLAM's is 82.5 Mamps. The settings are obviously different for varying monoblocks and even production runs as at times specs may change. Call the manufacturer.
The easiest thing, by far, is to call Cary and ask what they recommend.
Dear friends: I have been using the Valve Art KT88's in my 80 watt monoblocs under the following conditions: plate VDC 525; Screen VDC set at 325 VDC; and 50 ma idle per tube, which is 26.25 plate dissipation per tube at idle (max for the KT88 is 42 watts, some are up to 50+ watts) These conditions are also suitable for any 6550 as well. My primary load impedence on the OPT is about 5500-6000 plate to plate. I hope this helps.. Joe..aka the "Beam Tube"
Gus,In general (and take this with a big grain a salt), KT-88's can take more plate voltage, at the same bias, compared to the 6550.
Depends. If the 6550 are classic TungSols and the KT-88 are Chinese or Sovteks the difference in settings may not be that great.
Both KT-88 and 6550 put out a nominal 25 watts of plate dissipation per tube. So, roughly (plate disspation, watts) divided by (plate volts)x (1000mA per Amp) = (bias, mA). If you keep the same plate volts, plug in the KT-88 and up the bias, until you get the tone you want.
It may sound a bit more compressed at lower volumes, than the 6550, since, I believe the KT-88 likes more plate voltage and not neccessarily higher idle bias. That's how MOV got more power out of those bottles.
PS: you'll need to fiddle about a bit to get to the tone you want. Oh, BTW, if those are TungSol 6550 and you want to toss them---I'd be happy to take them off your shelf.
steve
Plate dissipation for kt88 (gec manual) is 35 watts design max. and 40 absolute max."Both KT-88 and 6550 put out a nominal 25 watts of plate dissipation per tube. So, roughly (plate disspation, watts) divided by (plate volts)x (1000mA per Amp) = (bias, mA). If you keep the same plate volts, plug in the KT-88 and up the bias, until you get the tone you want."
This is misleading, Steve, you'd better look over what you just said.
Story,You're correct. Just delete that whole portion. Brain went into tetany.
Thanks, for catching the error.
steve
no problem, Steve, have a good restful weekend.
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