Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: scstill on August 26, 2022, 09:39:55 am
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Starting this all octal project housed in a 40's small weekend/train/makeup case.
https://stillampd.com/weekender
Current schematic below. Couple of questions....
1) Where would be the best place to locate the tone stack?
before V1b with the Volume? or after V1b with the Master?
Thinking before so that V1b gain would help any loss from from the stack
2) Similar designs used a 6SN7 (.6a heater) for the PI
But The PT in its previous life fed 2.4a for the heaters (not sure its spec) and with the 6SN7 this tube complement needs 3.0a. So Thinking of using 6SL7 (.3a heater) as PI instead. Would the additional PI gain from 6SL7 cause any issues?
Would there be a risk to keeping 6SN7 and running this PT at 3a?
3) any other suggestions on design?
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The (your) 0.33uf usually goes to ground, not mid-tail.
What is "6BL7 340A per plate"? Sounds like welding.
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The (your) 0.33uf usually goes to ground, not mid-tail.
What is "6BL7 340A per plate"? Sounds like welding.
Can we weld with 6BL7? :icon_biggrin:
LTPI - Rk is 470k on top of 22k tail. This is certainly typo...
--Pete
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Yes several typos, Thanks will add corrected schematic
470k sb 470ohm
340ma sb 34ma
and 33k sb to ground
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Any thoughts on location of tone?
running PT with 3a to heaters?
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how many knobs does your guitar have?
if it's more than 1 i'd be inclined to use the guitar for tone n the amp for, well amp'n :icon_biggrin:
as for another PT, maybe a backer board like you have for speaker that holds the PS stuff, scabbed to side of your chassis, AWAY from the input stages n jacks
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i have had good results with a simple pentode preamp->phase inverter->output tubes amp using a vox-style cut control for tone (also either a rotary switch for coupling capacitor or for cathode bypass capacitor for bass control. few hundred nf-1uf-25uf works nicely)
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another tight fit
for less interference would it be better to keep the OT on the top or inside?
any thoughts for better layout? Chassis top is 5x7 and max'd out
PT on the left; OT in the middle/right
Tubes from left to right 6x5 (rect), 6bl7 (power), 6sl7 (PI), 6sl7 (pre)
Maybe 1/4" between PT and 6x5
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Surprised that nobody had any FB on the layout.
Hopefully silence is a good thing.
Anyway too late for change as chassis is fabricated and parts installed.
Will wire up in the next couple of days.
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In the "weekender" case