Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: archaos on June 17, 2020, 03:13:28 pm
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...Top Boost this time
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Hammond irons
PT : 290PX
OT : 1750T
Choke : 193C
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Preamp : 12AX7 x 3
Power amp : EL84 x 2
Rectifier : 5Y3
The first tube preamp has its triodes connected in parallel (110k on the anodes ; 25µF/1k5 on the cathodes), as well as 2 x 68k in parallel on the grids.
The second tube preamp is wired exactly as was the original AC30 TB cathode follower.
The PI tube is wired as well as was the original AC30 TB as a LTP with .15µF coupling caps.
125µF/100R on the EL84 cathodes giving about 12.5W (plate-to-cathode voltage = 281.22 ; voltage across cathode resistor = 8.78).
No hum, no parasitic noise or something else, just bliss. :icon_biggrin:
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Looks tight! Thanks for sharing.
What kind of speaker are you running?
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Thanks ! It's a pair of blue Celestions from the early 90's having some mileage.
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Did you build the cab too?
This is an incredibly sano build, very impressive.
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No I didn't. It's an original AC30 TBX combo cabinet converted in a spkr cab. My AC15 will be housed in a head cabinet which is far easier to carry.
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Looks great! Did you make the faceplate yourself?
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Looks great! Did you make the faceplate yourself?
Thanks ! No I didn't make it myself, I've just designed it with Inkscape then sent it to a custom shop to be laser engraved.
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Aha, another fan of RG316!
What pots are those?
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Aha, another fan of RG316!
What pots are those?
Yes, I am ! :icon_biggrin:
Those are Bourns PDA241.