Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on September 24, 2015, 04:56:49 am
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Parts came in yesterday (thanks Doug) So I knocked this one out for a friend. Pretty cool amp...
(http://p2pamps.com/tp/1.jpg)
(http://p2pamps.com/tp/2.jpg)
(http://p2pamps.com/tp/3.jpg)
(http://p2pamps.com/tp/4.jpg)
(http://p2pamps.com/tp/5.jpg)
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Looks good Mike!
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Looks good Mike!
Hey thanks Doug...
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With a nice 10" alnico speaker that is a really fun amp to play.
What transformers did you use?
What voltage on plate of 6V6?
I ask because I had to work to get voltages down to 5F2 levels. It was worth the effort since I wanted that warm tweedy sound and feel. So was an extra filter cap and choke before the power tube plate node.
Cheers,
Chip
P.S. A small thing but a log taper volume pot instead of linear taper would be a big improvement.
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With a nice 10" alnico speaker that is a really fun amp to play.
What transformers did you use?
What voltage on plate of 6V6?
I ask because I had to work to get voltages down to 5F2 levels. It was worth the effort since I wanted that warm tweedy sound and feel. So was an extra filter cap and choke before the power tube plate node.
Cheers,
Chip
Hi Chip,
Right now I am looking at 370 on the plates... The trannies are Heyboers.
P.S. A small thing but a log taper volume pot instead of linear taper would be a big improvement.
Thanks for the tip
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So does anyone think a 12" would totally suck in one of these amps?
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Almost like the Flintstones compared to your neat little Princeton Reverbs.
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So does anyone think a 12" would totally suck in one of these amps?
No, it wouldn't suck. Just need a bigger cab. However, there isn't enough wattage to really push any 12" speaker I can think of.
IIRC for a brief period on the '50s, Fender put the 5F2A circuit in a cab with a 10" speaker and called it a "Harvard". I can tell you that a Weber 10A100 is a great match for this circuit. "Warm, crunchy, early breakup. Compressed /fattened at high volume." Sounds about right. Ted recommended light dope If I remember right (sorry he's gone).
Cheers,
Chip
P.S. Should've started with "Another really nice, clean build."
One lead dress question - it looks like the junction of the two 68K resistors with the shielded wire going to the first triode grid is unsupported. Is there a turret under there not shown in the photo?
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No, it wouldn't suck. Just need a bigger cab. However, there isn't enough wattage to really push any 12" speaker I can think of.
Celestion Vox blue, 12"/15w. :icon_biggrin:
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Although it does not matter one iota, by custom, the red OT wire should go to the B+ and the blue should go to the plate of the output tube.
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Although it does not matter one iota, by custom, the red OT wire should go to the B+ and the blue should go to the plate of the output tube.
Except when it squeals.
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Although it does not matter one iota, by custom, the red OT wire should go to the B+ and the blue should go to the plate of the output tube.
Except when it squeals.
And boy did it squeal!
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One lead dress question - it looks like the junction of the two 68K resistors with the shielded wire going to the first triode grid is unsupported. Is there a turret under there not shown in the photo?
I use shielded cab for the input tied to the 2 68K resistors. Yes there are not turrets for that but I have honestly never had a problem. I know Marshalls and some other tie the 68Ks to the board but never have seen it on any Fender yet. So far it works for me. Good eye...
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That should not be a problem.
Those 68k carbons in that config are pretty stout