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Post by sonicboom on Oct 31, 2016 17:27:52 GMT -7
Hey guys I'm currently biasing my Amp and I have a confusion I need to decipher. My Euro tubes reader says the following: If you ask me, I managed to work around it to get the tone I wanted in the first place I would have never imagined that would be the reading. So my question is if I lower that to let's say 41mA-DC, or even 33 as the doctor recommends, will the amp get much cleaner. At the volume spot where I currently use it. This Amp is very loud so I really need it to start breaking as early as possible since it does have a loot of clean headroom. Can someone explain to me in detail how will the amp volume knob and tone response change once I lower those numbers. Thanks
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Post by sonicboom on Oct 31, 2016 17:37:37 GMT -7
Update! I'm still curious about the info I'm asking. But when I placed the reader on the other tube one was reading 41 and the other 29. So I'm changing them for a matched pair to see how it flows. Still I am curious as to whether bias it to 33mA or around 41mA which is the 70%.
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Post by Paul (TRANE) on Oct 31, 2016 17:58:55 GMT -7
From experience bias at 70% will give more cross over distortion and will sound harsher in the high end. Dropping down will give you a sweeter less harsh high end. The amp will still grind like a pro but tube life will also be lengthened at the lower mA setting. I usually go with Doc for bias. But of course you can try 50% 60% and 70% for idle. I like 60% a lot but 50 is great too. It is a matter of taste tone wise....not right or wrong. Do not go too high though or your tubes will not last long at all and die an early death.
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Post by sonicboom on Oct 31, 2016 18:18:23 GMT -7
So I inserted new tubes. One was reading 27 the other around 32. I got the hotter one up a bit until 36 which should balance both at about docs recommendation of around 33. Tomorrow I have band practice and will let you know my findings.
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Post by sonicboom on Oct 31, 2016 18:21:19 GMT -7
From experience bias at 70% will give more cross over distortion and will sound harsher in the high end. What do you mean by cross over distortion? Let me tell you Ive always thought the amp to be extremely bright. I have the bass knob at around 3:30.
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Post by Paul (TRANE) on Oct 31, 2016 18:31:39 GMT -7
Crossover distortion generally occurs when a power tube is ending a cycle and the other is starting up its cycle. You will find more of this when power tubes are mismatched. Get good matching tubes and bias them up and you should be good. That is my understanding at least. I am sure someone will correct me if I am wrong.
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Post by Paul (TRANE) on Oct 31, 2016 18:40:38 GMT -7
So I inserted new tubes. One was reading 27 the other around 32. I got the hotter one up a bit until 36 which should balance both at about docs recommendation of around 33. Tomorrow I have band practice and will let you know my findings. Cool. Let us know how it goes!
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Post by sonicboom on Nov 2, 2016 19:49:10 GMT -7
Didn't like it at all! I'm getting those Power Tubes hotter. Trying 40.
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Post by Paul (TRANE) on Nov 3, 2016 7:29:32 GMT -7
That happens, there is not exactly right setting for every player and situation. Let us know how how it goes.
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Post by sonicboom on Nov 3, 2016 13:01:17 GMT -7
Can someone confirm me that effectively hotter bias of the power tubes means earlier tube breakup?
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Post by DRZ on Nov 3, 2016 13:15:51 GMT -7
Yes it does. And 40mA per tube is fine for the HUGE KT 88's.
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Post by Jaguarguy (Mike) on Nov 3, 2016 15:56:58 GMT -7
KT88s??
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Post by DRZ on Nov 3, 2016 16:34:38 GMT -7
Oh did I say KT 88, meant KT 66 , sorry for any confusion. Worked today on a new Surgical Steel amp set, which I'll send to Dave Baker in Nashville for a combined Guitar/Pedal Steel video. Had the new Golden Lion KT 88's on my mind. Z
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Post by Jaguarguy (Mike) on Nov 3, 2016 16:48:44 GMT -7
Thought you might have been holding out on us with a new mod
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Post by riff1006 on Nov 10, 2016 13:26:28 GMT -7
I tend to gravitate toward 55-60%, give or take, season to taste.
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Post by perryr on Nov 28, 2016 0:06:08 GMT -7
Dug into my stash of Route 66 spares and pulled out a nice pair of GEC KT66's. I spent a good while playing at lower current like 33-34 and there was a certain cool quality, kinda added a Fendery edge. Ended up 38ish was where I seemed to like it best. Doesn't make much difference where it breaks up, amp is still creating the same watts right.. Just a little different character to the tone. Such a killer amp!
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