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Topic: Valco heater wires change? |
Steve Waltz
From:
USA
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Posted 6 Mar 2019 10:47 am |
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I have an old valco 12Ax7, 6v6, 5Y3 amp. I like it for recording but it would be nice to get it a bit more quiet.
The heater wiring looks odd. Wires come off the transformer and don't go to the pilot light but one leg grounds to the 5Y3 base, the other uses an unused pin of the 5Y3 then goes to one side of the filament of the 6v6 then one side of filament of the 12ax7, out the tied together pin 4 and 5 of 12ax7, then back to the 6v6 and back the the 5y3 base. So no twisted wires and the ones there don't seem to be trying to avoid other wires and they are very close if not sitting on top of others.
I was thinking of removing everything from the 5y3 base, use a twisted pair above and dropping down to hte 6v6 and then on in the same way to the 12ax7. Not ground to the chassis. I cold do an artificial center tap but I thought I would start and see how it goes.
Am I on the right track? Later I will add shielded wires to the volume pot as it is a bit far from the preamp tube. I have read that the on off switch on the volume pot can be an issue but I don't want to drill the chassis to add a new toggle.
Thanks,
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 6 Mar 2019 10:56 am
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Yep, I'd go back and do it like Fender... twisted pair, ungrounded, up away from the other wires. Hopefully you've done the three-wire cord death-cap mod too.
_________________
Too much junk to list... always getting more. |
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Steve Waltz
From:
USA
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Posted 6 Mar 2019 11:16 am
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| I did convert to a three wire power chord. Thanks for the confirmation on the method for wiring the heaters. |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 6 Mar 2019 12:59 pm
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Actually. early Fender heater wiring was just like that!
I have a 60's Airline that I've had since then, and it always was noisy. I dug it out quite a few years ago, and got it running again, moved wiring around, and made it quieter! |
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Jim Newberry
From:
Seattle, Upper Left America
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Posted 6 Mar 2019 1:23 pm
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I just restored a 1940 Oahu suitcase amp and to my surprise, it ran full dual heater wires and had a center-tapped PT for the heaters.
I'm about to repopulate a Fender 5F2A chassis and cab as a Valco 510-11 (Spectator) for fun. I love my little Oahu Sunshine amp, but wonder how the circuit will sound in a bigger box with a 10" speaker (although I have an 8" baffle for the cab, too).
This. Stuff. Is. Fun.
Jim
_________________
"The Masher of Touch and Tone"
-1950 Fender Dual Pro 8
-1950's Fender Dual Pro 6
-Clinesmith D8
-Clinesmith 8-string Frypan
-Clinesmith Joaquin
-~1940 National New Yorker
-~1936 Rickenbacher B6
-Homebuilt Amps |
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Steve Waltz
From:
USA
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Posted 6 Mar 2019 1:24 pm
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Bill, I hope my wire changes work as yours sounds like it did. This amp sounds good other than the noise and maybe some coupling capacitors that seem like they were installed for the 6 or 8" original speaker. I'm using and external 10" and I might play with other values to see if I can get a bit more full range. It seems a bit on the frequency filtered side.
Jim, the change to 10" speaker was a good one. I've even used a JBL 12" and that was good too. I think those original boxes were too small. Even my vintage47 amp I think would sound better in a bigger box. |
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Steve Waltz
From:
USA
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Posted 8 Mar 2019 9:46 am
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So I made the heater change and it had a serious buzz until I did the artificial center tap. One 100 ohm resister off each heater wire, then twisted together and grounded......just in case anyone ends up doing this type of thing.
When I have time I need to do more work to get the noise floor down. Waiting on some new shielded wire and considering changing the 10uf caps to 16uf and the 20 to 33. That seems to be Ok for a 5y3.
Is having the on switch being part of the volume enough of an issue that I should try mounting a new separate on-off? BTW this is an airline 62-9032. |
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