Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ginger on December 14, 2018, 11:00:54 am
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I added the Princeton trem circuit to a 5E3....didn't do much , barely audible.... how about this circuit ?....
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sure
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Tried it... in order to get enough intensity... the pumping of the the trem makes it unusable... tried everything , tapping off of different power nodes , etc . This is a 5E3 , built into a Guild cab / chassis
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Haven't read any success stories about adding trem to a 5E3 , which is odd
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I'll just convert to fixed bias i guess... Harvard
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You replaced a 1M with a jumper. Pull that jumper out and replace with a 220K. Any better?
If any pumping, put a diode across the outer lugs of the intensity pot, cathode to ground. Any better?
Don't convert to fixed bias just yet. I have one more trick that should get you enough trem if the above is not sufficient. If you do decide to convert to fixed bias copy the 6G3.
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Yes , thanks.. did ALL that... I've built many amps with trem... the 5E3 does not want to cooperate
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To be specific. I rebuilt this amp for someone... the Guild was really lackluster . He wanted a 5E3 with tremolo , so , i transplanted the simple trem from a Princeton... to not much effect , ( and i tried the usual... different taps... diode across the intensity pot , etc. ). So , I actually used the trem from the layout above , before , in a cathode biased Princeton... worked great.... but not in this one . The trem doesn't come alive until maybe 8 on the 1 meg pot.... then , the thumping ... I know trems thump , but this is interfering with the signal , and distracting from the enjoyment of the amp... the layout of my build is nice, and logical .
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Also... one more thing... the amp sounds wonderful... like a 5E3 should... just the TREMOLO is giving me fits
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Replace the 3.3K and 25µF cathode cap with a red LED, cathode connected to ground.
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Yes... I can do that quickly... just the damn thumping... if the intensity picks up... I imagine the thumping will too... yes ?
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Anyway... thanks... i do have room on the board to convert it to fixed.... no one can hear the difference anyway
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I have a very similar cathode biased 6V6 amp with tremolo. No pumping or thumping.
http://sluckeyamps.com/RCA/Ampeg_J12B.pdf
I don't think converting to fixed bias will eliminate your issue.
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Okay... i'll take a look ... thanks
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Just curious.... why do you think changing to fixed bias won't eliminate my issue ? I can make the trem very strong with the existing circuit , but as you know ... the thump. The only difference with this layout is.... the trem pots are a mile away from the circuit... the last two pots on the right .
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Why do you think it will?
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Good question.... I guess I've seen a lot of posts lately about problems with trem in cathode biased amps .
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There are probably more cathode biased 6V6 amps than fixed bias 6V6 amps that use this type tremolo. Your layout could be a factor. Looks like the trem circuit is right next to the preamp circuit and then those long leads to the pots probably pass by some other sensitive stuff. Try this... Get the trem to thumping. Then pull V1. Thumping stop? Pull V2. Thumping stop? If thumping continues, then it's probably not being picked up by V1 or V2.
Don't you have a spare triode in that third tube? If so, build the 6G16 trem circuit. Any better?
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The thumping stops when I pull V2
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Just one more thing , then I'll drop it...I'm probably beating this subject to death ... the intensity doesn't come on until about 7-8 on the brand new Alpha 1M audio pot... can you see any reason for that ? Do you use audio or linear taper for the intensity ?
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The PR and the 6G16 both use a 250K linear pot. That's what I'd use in your amp.
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ok.... back in it goes
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Okay... as it stands now... the trem is tapped off the B+... LED in place of 3.3K resistor / cap......straight wire , no 1M resistor , as seen in the above layout ... and diode across a 250K linear pot . Not much thumping , and not much intensity either until the intensity pot is maxed . The plate voltage in this amp is extremely low... 355V... I wonder if that is the intensity problem . Anyway , thanks
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Okay... as it stands now... the trem is tapped off the B+... LED in place of 3.3K resistor / cap......straight wire , no 1M resistor , as seen in the above layout ... and diode across a 250K linear pot . Not much thumping , and not much intensity either until the intensity pot is maxed . The plate voltage in this amp is extremely low... 355V... I wonder if that is the intensity problem . Anyway , thanks
OK, put the 1M back in. Put the .02µF cap back in. Remove the diode from the pot. Leave the LED in. Let's call this the new baseline circuit and work forward from this. How does it behave with this baseline? I don't think the B+ is an issue.
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Yeah... hello again... I never removed a .02 cap . i'm set up with jumpers , every change is quick . I've had.. 2 X .02 and one .01 cap in the trem section all along , like one might use to slow the trem on a Princeton
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Well, you removed a .02 from the doctored PR layout you posted. I'm not talking about the three caps in the osc. feedback path.
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It behaves like a very shy trem that doesn't want to be heard... even at max intensity . See , I know Princetons , and you would think this trem circuit would behave the same way in a 5E3 , with a couple of voltage changes . Ok... square one... back to above layout .
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No... the .02 is two caps over to the right , from the .01 , .02, .02 caps
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OK, I'm lost again. Did you put the .02 cap back in. Did you leave the LED in? I need to be on the same page with you so help me out.
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.02 was always there... I only changed one cap... to slow the trem . I only went from the usual PR trem circuit , to the one I've posted . Now it IS the one I've posted , but with an LED
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See the blue .02 cap? You removed it from your original pic. PUT IT BACK. While you're at it move that red 1M resistor back to where it is supposed to be.
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Was always there... underboard connection to .1 cap
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OK, I think I'm about to catch up. I've been working from the first pic you posted all this time. I can't look at the photo and tell what is connected to what, especially under the board. Can you post a layout of your actual amp?
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Yeah... i understand...mine is just a 5E3 , with a Princeton trem tacked on , where it should be . It is acceptable once you hit 8 on the intensity ... My trem layout is what I've posted , exactly where it would be , on a PR . Like a cathode biased PR , with trem.
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glad you got it figured out
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Ginger, I found the 5E9's trem circuit to be more useful. PI instead of Cathode. (http://ampwares.com/schematics/tremolux_5e9a.pdf)
sound byte: https://www.youtube.com/watch?v=acFs3iYGt0c (https://www.youtube.com/watch?v=acFs3iYGt0c)
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No , i haven't figured it out , but i appreciate your willingness to try... i'll get it
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And when i DO.... I'll dominate the world , with the best trem
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thank you Vampwizard