Anyone know what the prime culprit of lowered clean headroom might be. I am running JJ KT66's and various preamp tubes (mullard, amperex, and a JJ I think). The JJ's have some hours on them but I would not think enough to effect output. Could I be wrong there?
I played out with another guitar player who was using a Fulltone OCD and a Deluxe Reverb and he was killing me. I also compared it with a THD Bivalve (30) that I have running el 34's and in the hi V setting the THD was clearly much louder. I also feel like the amp used to stay cleaner higher up on the volume knob.
decreasing headroom?
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DRJUSTIN
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SteadyEddie
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Re: decreasing headroom?
I heard those new KT66s have a bias drift. Check your bias.
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Mars Hall
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Re: decreasing headroom?
In my experience JJ's have a reputation for a short life span.
"You just slide a bottle up and down til what you want out of it comes out. You just slide away at it til you've got it down." Duane Allman
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DRJUSTIN
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Re: decreasing headroom?
I will check the bias. While I'm at it I do have an old set of Tung Sol 5881's I can pop in and see what happens.
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PCollen
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Re: decreasing headroom?
Power tubes, perhaps, but the ECC83's have lasted years for me....Mars Hall wrote:In my experience JJ's have a reputation for a short life span.
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PCollen
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Re: decreasing headroom?
Forget the other guitarits and their amps, they may have been LOUDER than your amp all along. How much lower in VOLUME is YOUR amp today than it was a month ago (or whatever your base timeline is) ? Note: LOUDNESS/VOLUME is not the same as headroom.DRJUSTIN wrote:Anyone know what the prime culprit of lowered clean headroom might be. I am running JJ KT66's and various preamp tubes (mullard, amperex, and a JJ I think). The JJ's have some hours on them but I would not think enough to effect output. Could I be wrong there?
I played out with another guitar player who was using a Fulltone OCD and a Deluxe Reverb and he was killing me. I also compared it with a THD Bivalve (30) that I have running el 34's and in the hi V setting the THD was clearly much louder. I also feel like the amp used to stay cleaner higher up on the volume knob.
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DRJUSTIN
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Re: decreasing headroom?
Nah I was playing with the same guy in my band the whole time. It was definitely losing something. I also compared it to another of my own amps that in the past did not have the same output and it failed that test too.
I ended up following a previous suggestion(thanks!) and checking the bias on the J tubes and indeed they had drifted in the cold direction about 6 clicks. I also think one of the old Mullards I was using was giving up the ghost sadly. Rebiased and replaced the Mullard and it was back to being too loud again!
That's how I really knew something was wrong - I could use it in rehearsal and turn it up without an attenuator.
I ended up following a previous suggestion(thanks!) and checking the bias on the J tubes and indeed they had drifted in the cold direction about 6 clicks. I also think one of the old Mullards I was using was giving up the ghost sadly. Rebiased and replaced the Mullard and it was back to being too loud again!
That's how I really knew something was wrong - I could use it in rehearsal and turn it up without an attenuator.
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SteadyEddie
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Re: decreasing headroom?
Glad it helped. There's no way no how a Deluxe Reverb (and I love those amps) should drown out a Marshall.
I remember reading something about the new production KT66's. I'm sure JJ's are in that run of Chinese tubes. I've got a set that I've run in my plexi but I've been too scared to actually take it out playing after what I read. Damn shame because it's got this big, tight bottom end I can't get from EL34's.
I remember reading something about the new production KT66's. I'm sure JJ's are in that run of Chinese tubes. I've got a set that I've run in my plexi but I've been too scared to actually take it out playing after what I read. Damn shame because it's got this big, tight bottom end I can't get from EL34's.
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DRJUSTIN
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Re: decreasing headroom?
Yes Thanks!
I would not hesitate to play out with them though. I have used these tubes flat out for quite a while before this happened. They are good to go now.
I also should add these tubes took care of the standby switch squeal that the original valve arts tubes caused without any other circuit mods.
I would not hesitate to play out with them though. I have used these tubes flat out for quite a while before this happened. They are good to go now.
I also should add these tubes took care of the standby switch squeal that the original valve arts tubes caused without any other circuit mods.