Ken: WHY must the heater be this way?

[Geezer]

  Hoffman Amplifiers
    > Tube Amp Building - Tweaks - Repairs
        > Ken: WHY must the heater be this way?      
 
<< Prev Topic | Next Topic >>  
Author  Comment  
gammelnalle
Junior tube assistant
Posts: 18
(2/23/04 5:10 am)
 Ken: WHY must the heater be this way?
--------------------------------------------------------------------------------
 In an answe resently you stated :
Ken:
EDIT: also make sure the heater wires are not cris-crossed on the power tubes. Make sure the same wire go to the same pin on each tube--say 4 to 4 and 5 to 5--Not 4 to 5 and 5 to 4.

I take your word for it , but I'm a curios dumb swede who always wanna know..... so WHY!!! ???
 

cheers from sweden
 

 
bluesbear
Hey get your own solder
Posts: 340
(2/23/04 8:00 am)
 Re: Ken: WHY must the heater be this way?
--------------------------------------------------------------------------------
 Maybe I shouldn't answer for Ken.. but here's what I understand of this:
Wiring the power tubes this way reduces the hum induced by the filament circuit. As I understand it, wiring the other way doesn't induce hum, the hum is already there. Wiring it correctly just reduces it. This is why a single ended amp like a Champ is harder (but not impossible) to make hum-free. There is only one power tube so there is no way to wire it the way you describe. If you ever read anywhere about the heaters being wired "humbucking", this is what they're talking about. I'm not sure why this works. I only know it does. I've tried it both ways just to prove to myself that it does.
How'd I do, Ken?
Dave

Edited by: bluesbear at: 2/23/04 8:05 am
 
coap01
Junior tube assistant
Posts: 105
(2/23/04 9:16 am)
 heaters
--------------------------------------------------------------------------------
 This is the way i see it. The green wires even tho they supply same voltage/current, are 180 degrees out of phase. That means that when one wire is on the positive part of the sine wave, the other wire is on the negative.

You want the same wire going to the same pin because you want the tubes with be heates in phase...so to say.

umm so thats what makes sence to me, but i'm sure Ken will have a simple answer

--Lev
 
GroundhogKen
Forum Moderator
Posts: 2291
(2/23/04 11:25 am)
 Re: heaters
--------------------------------------------------------------------------------
 If each power tube generates a certain amount of hum and each half of the push pull circuit has the same filament polarity, then the hum is cancelled at the output transformer.

It's that same old differential amplifier concept.

Which is pretty much what everyone stated above.


Ken
 
gammelnalle
Junior tube assistant
Posts: 19
(2/23/04 4:47 pm)
 Re: heaters
--------------------------------------------------------------------------------
 Aaarg !!!
Its so very easy.... once you see it !!!!

Tanx a lot guys!!!
  
 
R8burst
Junior tube assistant
Posts: 23
(2/25/04 2:38 pm)
 heater wiring
--------------------------------------------------------------------------------
 Could someone reference the original post that contained Ken's answer on this heater wiring question? I did a search but couldn't find it.

Thanks
Tony
 
GroundhogKen
Forum Moderator
Posts: 2300
(2/25/04 7:33 pm)
 Re: heater wiring
--------------------------------------------------------------------------------
 Someone had a thread about an amp with excessive hum. I suggested check the heater polarity on the power tubes.

I can't really take any credit for it--I was just spitting out what I had already read on Doug's Heater page.

www.hoffmanamps.com/fenderservice4.htm

Ken
 
 
 << Prev Topic | Next Topic >>

 

 Topic Commands
 Click to receive email notification of replies
  
jump to:  Tube Amp Building - Tweaks - Repairs (New)New Product Suggestions (New)Praises - Complaints - Suggestions (New)Buy - Sell- Trade (New)Archives (New)    
 

- Hoffman Amplifiers - Tube Amp Building - Tweaks - Repairs - Hoffman Amplifiers -



Powered By ezboard® Ver. 7.32
Copyright ©1999-2005 ezboard, Inc.