wiring heaters...ugh

[amplifiednation]

I'm on my first amp build and was having a hard time getting both 18 guage wires in the noval socket lugs. i was having to take some strands off, which looks sh*tty. so i'm gonna go home in a few (don't tell work) and try some solid core 20 guage. i think i have some. then lets see if i can make this look a little better.

[martin manning]

...I have used 22, 20, and 18 under different circumstances and without a second thought. Remember, the last bit of wire in the string only has to carry enough current for the last tube, for a 12AX7 that's 0.3A, which isn't very much. For the first tube, the wire has to carry the whole load of all the filaments, depending on the amp, probably 2-4A. This probably requires something larger than #22.

Depending on the layout, the only wire carrying the entire filament string current might be the leads from the PT. With four EL34's in the amp, the rest of the heater wiring would then need to handle 3*1.6 = 4.8 for the power tubes, leaving enough capacity for a half dozen 12A_7's using 22 ga. wire.

[amplifiednation]

Working on my first rocket build. I read this thread this morning and I think my heaters came out ok (which I did this evening). Do they look alright? There's a bit of a mess by the terminal strip. I probably should have allowed more room there.

[surfsup]

Taylor, is that a rocket you're building?

I'm no expert but I have read 1000 heater wire posts and redone my heaters seemingly an endless amount of times. I think you have the same wire twisted quite a bit going to the tubes. This is of little or no benefit as I understand it. Also the last preamp tube has a hum-inducing looparound. I found it better to come in straight toward the socket (diametrically) and not run right around it. But wait for a more experienced forum guru to tell you what's up.

You can see some of my heater wiring:

[img1000]http://chicagocadcam.com/ChrisHahn/PRE.jpg[/img]

[amplifiednation]

Nice well that makes sense about the last preamp tube. I can fix that. Did I wrap the wires too tight? What about the rest of the work?

[amplifiednation]

Yup it's a rocket!!

Taylor, is that a rocket you're building?

I'm no expert but I have read 1000 heater wire posts and redone my heaters seemingly an endless amount of times. I think you have the same wire twisted quite a bit going to the tubes. This is of little or no benefit as I understand it. Also the last preamp tube has a hum-inducing looparound. I found it better to come in straight toward the socket (diametrically) and not run right around it. But wait for a more experienced forum guru to tell you what's up.

You can see some of my heater wiring:

[img1000]http://chicagocadcam.com/ChrisHahn/PRE.jpg[/img]

[surfsup]

What other work are you referring to?

In terms of tightness, many here do "vintage" clones and wrap them "loosely" to mimic the same build style on the TWs as I understand it. So that is purposely done. EDIT: In my heater research, I learned if you're going to do the twisting, 3 full twists per inch is the goal. I worried about the 20awg solid core snapping but finally just twisted the heck out of them with a drill.

You seem to be using stranded. Again, though, wait for someone else to respond as I'm not an expert at all.

BTW< nice restorative work at your site.

[amplifiednation]

I guess just overall. Once I fix that last tube am I good? I used solid core. Tried stranded. It wouldn't fit in the lugs. I gave up on that.

Thanks glad you liked the work!

What other work are you referring to?

In terms of tightness, many here do "vintage" clones and wrap them "loosely" to mimic the same build style on the TWs as I understand it. So that is purposely done. In my heater research, I learned 3 twists per inch is the goal (so you should see 6 color twists, 1/2 for each). I worried about the 20awg solid core snapping but finally just twisted the heck out of them.

You seem to be using stranded. Again, though, wait for someone else to respond as I'm not the expert at all.

BTW< nice restorative work at your site.

[amplifiednation]

I redid the heaters on the power tubes to try to allow for more room to negotiate the other parts in. I also simplified the wiring from the terminal strip and fixed V1 heater so there is no loop around the left side of the tube.

I hope I got it right this time...this was the third fix. Also, i made sure to maintain "polarity" on the power tube lugs.

[surfsup]

Yours looks like a Rocket. I am planning to do one too, and looking at yours I would probably run my heaters for the PTubes to the bottom of the pic since the pins are at the bottom, you wouldn't have to have the hum loops around the right sides of each socket. JMHO - but again, someone more experienced should tell you what's up. Surprised no one else has opined yet.

[mcrracer]

Maybe I missed it but what preamp tubes are you using?
There's nothing wrong with the power tube heater wiring.

[amplifiednation]

Yours looks like a Rocket. I am planning to do one too, and looking at yours I would probably run my heaters for the PTubes to the bottom of the pic since the pins are at the bottom, you wouldn't have to have the hum loops around the right sides of each socket. JMHO - but again, someone more experienced should tell you what's up. Surprised no one else has opined yet.

I was thinking the same thing, and it would have been easier to do the wiring, but the layout I'm using has signal wires to the OT going from the bottom of the EL84's, around the terminal strip and to the OT. They won't cross over the heaters this way.

[amplifiednation]

Maybe I missed it but what preamp tubes are you using?
There's nothing wrong with the power tube heater wiring.

12ax7's and EL84's.

I think the concern wasn't the actual wiring, I'm just trying to figure out the best place to put all these wires!! I had them twisted up a ton last night and they were taking up a lot of space (see posts above). So this is my revision, trying to clean it up and simplify to make room for other parts.

[mcrracer]

My vision isn't the best as I am blind in one eye, but to me it looks like you miswired the heaters on all of your preamp tubes. Pins 4 and 5 should be wired together and the other heater wire going to pin 9 as you have them.

[NickC]

My vision isn't the best as I am blind in one eye, but to me it looks like you miswired the heaters on all of your preamp tubes. Pins 4 and 5 should be wired together and the other heater wire going to pin 9 as you have them.

You are right. Pin 4 and 5 should be wired together. Heater supply then goes one side to pins 4/5 and the other to pin 9.

I just wired up heater supply for a Deluxe Reverb build the other night and have a picture of it:
[img1728]http://homepage.mac.com/swamptone/Delux ... assis2.jpg[/img]