Hi, Just a quick question, I have noticed that in some pics of an TWExpress, The 6.3 wiring from one output tude to the other are out of phase, is there any reason for this or is it ok to go either way.
Peter
6.3 volt wiring
Moderators: pompeiisneaks, Colossal
Re: 6.3 volt wiring
If it's the output tube section it's not a big deal but I always wire mine consistently from tube to tube.
If your talking about the original TW pictures that show out of phase wiring your correct there are some pictures noting that.
If you have seen clones wired that way, the builder probably followed the original TW pictures for correctness to Ken's build.
If your talking about the original TW pictures that show out of phase wiring your correct there are some pictures noting that.
If you have seen clones wired that way, the builder probably followed the original TW pictures for correctness to Ken's build.
Re: 6.3 volt wiring
Yeah, I'm pretty sure they are out of phase in or to reduce the heater hum, you know out of phase = zero, I think. Every little bit helps.
Re: 6.3 volt wiring
On the output tubes, if the heater wiring is out of phase it will actually increase hum, not decrease it.
Each tube is connected to opposite sides of the transformer, so has its signal inverted in the OT.
Therefore if you have your OT heaters in phase at the tubes you will get the common-mode noise cancelled in the OT.
Each tube is connected to opposite sides of the transformer, so has its signal inverted in the OT.
Therefore if you have your OT heaters in phase at the tubes you will get the common-mode noise cancelled in the OT.
Re: 6.3 volt wiring
You won't see much difference on the preamp tubes because each has two triodes anyway, both of which are out of phase with each other anyway, and with increasing gain, so the noise introduced at V1a will always dwarf the noise induced further along the chain.
I'd say that most of the improvements people have seen will be down to lead dress more than anything else.
The power tube phasing is an absolute though, and you should keep both power tubes with the heaters wired in phase. If you've got 4 power tubes then you can do them - + + - or + - - + to maximise common-mode rejection between adjacent pairs even before relying on the balance of the OT secondaries, but it's almost moot as the gain is so comparatively low at this point anyway.
I'd say that most of the improvements people have seen will be down to lead dress more than anything else.
The power tube phasing is an absolute though, and you should keep both power tubes with the heaters wired in phase. If you've got 4 power tubes then you can do them - + + - or + - - + to maximise common-mode rejection between adjacent pairs even before relying on the balance of the OT secondaries, but it's almost moot as the gain is so comparatively low at this point anyway.
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Gibsonman63
- Posts: 1033
- Joined: Wed May 27, 2009 1:59 pm
- Location: Texas
Re: 6.3 volt wiring
Fender put the heater wiring in haphazardly on the blackface and silverface era amps. Correcting the power tube heater wiring polarity has reduced buzz in the ones I have worked on and moving the pre-amp heater wiring around with a chopstick has much more of an effect than I would have thought, so I can imagine what it does for a high gain amp like a Wreck.