Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Shack on February 23, 2016, 08:21:57 pm
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does it make a difference if the heaters are wired where all the pins 9 are same wire and 4,5 the same wire, and same with power tube pins? I ask cause if you use green twisted wires, you dont know if they are wired that way unless you check each tube....and dont know if it matters being AC voltage. would like to know before I wire my new allen PT in . could use two different wire colors for them if it does make a difference :)
This princeton reverb will be sweet, with a custom oak cab and im trying to make it as neat as a mscaggs PR......if thats even possible
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Hey guy!
Yeah it does make difference if you keep one wire on pin 4-5 and the other on pin 9, a wires jumping pins can cause hum, use different colors to avoid that !
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> all the pins 9 are same wire and 4,5 the same wire
I vote "no".
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From Doug's site
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Heater hookup
(http://el34world.com/charts/images/heater.gif)
The 6.3 volt heater wires come out of the power transformer and they go right to a light bulb fixture to power the pilot lamp. This is a common arrangement on Fenders. The lamp is a convenient terminal on the way to the power tubes. From the lamp you can then run a twisted pair of 18 Gauge wires over to the first power tube. Pins 4 and 5 are jumpered together on 12A*7 type pre amp tubes. 20 Gauge wire is fine for the pre amp tubes.
If you do not have a heater center tap on your power transformer, you must run two 100 ohm 1/2 watt resistors to ground to create an artificial center tap. If you do not have a center tap, you will get 120 cycle hum. Each 100 ohm resistor is soldered to one of the heater wires. The other ends of the 100 ohm resistors are twisted together and then soldered to ground.
If your power transformer has a center tap wire, solder that to ground. Most power transformer heater center tap wires are green with a yellow stripe.
The heater wires are usually run up in the air, above the tube sockets in a twisted pair. Twisting the heater wires cancels hum. This is why phone line wires are run in twisted pairs. The twisted pair wires drop down and get soldered to the tube socket pins. The twisted pair continues down the line to every tube in the chain.
Keeping the wires in phase helps with hum sometimes. In other words, pin 7 on one power tube goes to pin 7 on the next power tube. Pin 9 on a pre amp tube goes to pin 9 on the next pre amp tube. EL84 power tubes heater connections are pins 4 and 5. Most other 8 pin power tubes use pins 2 and 7.
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Lol,,,,,thank you mscaggs....I know how to do heater wires.....just wondered about the phase I suppose. I know that my twisted wiring in last years 5E3 isnt in phase (unless I got real lucky) and it still sounds great, just thought id ask before I wired up this Princeton.
Seems it would be hard to keep them in phase if the wires are the same color.
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Lol,,,,,thank you mscaggs....I know how to do heater wires.....just wondered about the phase I suppose. I know that my twisted wiring in last years 5E3 isnt in phase (unless I got real lucky) and it still sounds great, just thought id ask before I wired up this Princeton.
Seems it would be hard to keep them in phase if the wires are the same color.
I figured you knew how to wire heaters :) The picture and the verbiage suggest to keep heaters in phase. I always do and have found a few humming amps where the heaters were outta phase and making it in phase solved the issue.
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You can do like many others, and go green/black, red/black, or what ever two colors you like - wouldn't it be cool if someone made a wire that was green with black dashes on it -- or something like you see in auto's. Then you could use green/green-blk for Fender vintage stuff. Some of the wire I pulled out of that 56 Baldwin organ had really nice dual color schemes to it, and it was cloth covered.
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Seems it would be hard to keep them in phase if the wires are the same color.
Not if you use an ohmmeter.
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Now I'm wondering, does it matter which orientation the tubes are in. For instance, I notice in Hoffmans link Mscaggs posted that the small bottle pins 4/5 connect to the power tube pins 7. Is this intended ---- would it be ok for small bottle pins 4/5 to connect to power tube pins 2? And vice versa?
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And is there a North and a South for windings of transformers? Is there an electro-magnetic orientation to the windings?, we see it on guitar pickups. There might be something to this in transformers and tubes too.
On output transformers there is definitely an out of phase condition, that is unpleasant to the ears. So I'm wondering about power transformers. Could it be possible that there is an in-phase and out of phase condition for the windings? maybe relates to hum issues? ( I hope I haven't traveresed into gonzo territory here)
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I always do and have found a few humming amps where the heaters were outta phase and making it in phase solved the issue.
Now that is very interesting. :icon_biggrin:
HBP and others here have tried it both ways and reported they heard no difference hum and I believe them.
But, I wonder if it is because of an occasional bad tubes (alignment/leakage?) or something to do with certain PT's that keeping the heater wires in phase correct it?
I have been using 2 different colored heater wires and will keep doing so now as I was thinking of not bothering any more.
I'm going to think of it as 'just in case' insurance, just like a dcv standoff on the heaters. :undecided:
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A long time ago all wire was white and filament phasing was not an issue. Then someone discovered the rainbow and thought those colors would look pretty in a guitar amp. And phasing became a BIG issue. :wink:
Guitar guys get used to seeing 12AX7s and 6L6s and EL34s and kinda lock in on the idea that pins 4, 5, 9 or 2, 7 are filament pins. And the phasing controversy becomes more complex when you mix those tubes together, especially with different colors and wire sizes. But there are plenty of other tubes that have been used in guitar amps that use different pins for heaters. For example, 6EU7 uses pins 1, 2. 6SN7 uses pins 7,8. There are others that use different pins for filaments also. How the hell are you gonna string all those different tubes together? As far as I know, there has never been a standard convention for proper phasing of all these different filament pin assignments. And if I say it doesn't matter, is that really true?
Don't fret too much about it. New technology promises tubes that will be solar heated and finally proper phasing will become a non-issue. :icon_biggrin:
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Don't fret too much about it. New technology promises tubes that will be solar heated and finally proper phasing will become a non-issue. :icon_biggrin:
Oo, Oo, I want me some of those tubes! :laugh:
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Don't fret too much about it. New technology promises tubes that will be solar heated and finally proper phasing will become a non-issue. :icon_biggrin:
Where shall we install the solar cells?
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Where shall we install the solar cells?
No no. Not solar powered. Solar heated. There you go fretting about it. It's all tied to the sun becoming a red giant. The entire earth will become solar heated. I just assumed that meant tube filaments too. It's still a ways off.
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Seems it would be hard to keep them in phase if the wires are the same color.
Not if you use an ohmmeter.
This was the very first thing that came to mind- a simple continuity check should keep the phasing correct. This is especially useful, as mentioned above, in Fender and Valco style builds where both sides of the filament tap is green 16 or 18 gauge wire- twisted. Out of phase filaments means noisy output- almost always. Almost. ;)
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> all the pins 9 are same wire and 4,5 the same wire
I vote "no".
I think an argument could be made for alternating the wires from preamp tube to preamp tube. In order to cancel hum the alternating wires must be twisted tightly. If you have the positive wires going to 9 and the negative wires going to 4,5 then there will be a longer point of untwisted alternating wires, at the worst place, right at the tube socket where interaction with the grids would be possible. If you alternate wires you can twist almost all the way to the socket pins. At least this seems logical to me. I have read that keeping the wires in phase where the power tubes are concerned is important. Don't know if that is true or not.
Not too worried about solar heating causing my demise. Makes more sense to me to worry about being hit by an asteroid. More evidence that we have been hit by significant asteroids then a history of the sun melting away.
I choose to not be concerned about either. Spent more than five weeks in a comma after a AAA rupture. Have learned not to worry about most things. Some things you can't control, so you just have to roll with the punches.
Thanks
Mike
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All I know is Global Warming seems to be our biggest threat (Sarcasm)
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does it make a difference if the heaters are wired where all the pins 9 are same wire and 4,5 the same wire, and same with power tube pins? ...
I vote "no". At least, I've never found an amp where it mattered one way or the other.
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I know for fact that hum in one stage can't "cancel" hum in another stage, except by critical coincidence.
("My" Ampeg V-40 had one hum at zero Volume, this reduced to about "3" on the knob, then increased from "3" to "10". The first two stages had similar hum, but generally different signal levels, and out of phase. If VOL was cut-down just-right to negate the first stage gain, the two hums cancelled. But you don't run a VT-40 at "3". And the setting was very critical.) (This VT-40 had a design problem: heaters on PCB. No twist, little separation from critical audio points.) (It also had a hum-dinger but again the "best" setting depended on gain and tone settings, the hum never really went away.) (The salvation was the open-back box. Hum was pretty pure 60Hz. If you put your ear near the front or back it was loud. If you moved back more than one cabinet width, all the hum cancelled front-back.)
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All I know is Global Warming seems to be our biggest threat (Sarcasm)
Nuclear war is our biggest threat, but it is not for sure. Global warming is an extremely serious threat and it IS for sure (dead serious). It doesn't matter how you hook the heater wires up.
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Thank you all for the input I needed, ill phase them cause I can even tho it may not matter :)
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... ill phase them cause I can even tho it may not matter :)
That's an honest and valid choice!