Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: MakerDP on July 05, 2014, 02:11:05 pm
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Hi everyone,
Someone at AX84 suggested I come over here and ask if there was anyone who could point me to pics of their layouts using zip-cord for heater wiring. All of my Google-foo is coming up empty. :dontknow:
Thanks!
DP
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:w2:
OK.... That's certainly an interesting response... Not sure how you could even think it was a "dis" of this forum??? It was simply someone trying to help saying that someone here actually taught him how to use zip cord (or lamp cord if you prefer) for their heater runs. Here, look for yourself... http://ax84.com/bbs/dm.php?thread=485465 (http://ax84.com/bbs/dm.php?thread=485465)
Sluckey's name came up as the possible source, but I looked at his website and all of his builds use the twist method.
Anybody have any helpful pointers?
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Our host Doug sells zip cord in his on line store.
I think I remember something about Doug and Physconoodler talking about using it once before. Physco said he did try it once and he thought it worked just fine as far as low noise.
You can find it here, just scroll down;
http://hoffmanamps.com/MyStore/catalog/parts18.htm (http://hoffmanamps.com/MyStore/catalog/parts18.htm)
Brad :icon_biggrin:
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I have never used zip cord for filaments and don't recall ever suggesting using zip cord for filament wiring. And I can't recall any recent threads about using it either, although I do think maybe Physconoodler mentioned it a few years back. Send him a PM. I did use shielded twisted pair (STP) to build an umbilical cord between the preamp chassis and power amp chassis in my "Stuffed Vox (http://home.comcast.net/~seluckey/amps/vox/vox.htm)" project. But once inside the chassis, I twist filament wires.
I think Moonbird may be mistaken about learning that trick from me. Now I have used plenty of zip cord for lower power speakers.
That's certainly an interesting response
Yes it is. Gonzo speaks for himself and no one else on this forum. I certainly didn't take that post to be disrespectful in any way.
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I used zip cord on my last little build. (lamp cord wire, actually) 2 gain stages and power tube is all it was. Basically, just treated the zip cord as a pre-twisted pair of wires, and shoved it in the corner of the chassis. The amp is not dead quiet at full volume, but then none of mine ever are. :laugh: But with volume down, there's no hum, hiss or other strange cat-like noises.
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Awesome. Thanks for the helpful responses folks. I will agree with Gonzo that your builds are very nicely done, Sluckey! :icon_biggrin:
I used zip cord on my last little build. (lamp cord wire, actually) 2 gain stages and power tube is all it was. Basically, just treated the zip cord as a pre-twisted pair of wires, and shoved it in the corner of the chassis. The amp is not dead quiet at full volume, but then none of mine ever are. :laugh: But with volume down, there's no hum, hiss or other strange cat-like noises.
OK so you just routed it like you normally would then. Did you try and keep it as flat as possible? What gauge did you use? I built a simple stand-alone two-tube push-pull reverb unit that is in a pretty tight chassis and it has a little hum problem. I was going to try to rewire it with zip cord to see if it helps any. My heater twisting... well, I need a little more practice put it kindly. :l2:
Now I need to go look at Doug's switching stuff on the site. My next project will be a channel-switching preamp.
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Wire is wire.
I've used Zip for the darnest things, even microphones.
I suppose I would use it for heaters, but I do not see ANY advantage hum-wise. By conventional experience, you would want to *twist* the Zip so any given audio point is equally exposed to *both* sides of the 6VAC, and maybe cancels. And if you are twisting, it would really be easier to just get two wires and twist, instead of fighting Zip's natural flatness.
Hum can have MANY causes. In preamp work, one technique is to get a big 6V lantern-battery to power the heaters for a test. Then you know it is/isn't heater hum. You can move on to study your enclosure, B+ filtering, and proximity to wall-power wiring.
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> My heater twisting... well, I need a little more practice
It's like music. Practice may not make perfect, but less flubs.
Don't twist in-chassis (IMHO). Get a long wire, double it. Put one end over a nail in your bench. Chuck the other end in a hand-drill (or super-slow power drill). Twist. Now cut into the runs you need. Leave extra for where you must un-twist and route to the socket. But keep the untwisted lengths as short and direct as possible (6V on 12A_7 is the worst for this) and well away from the audio pins and related parts/wires.
There should be a couple of twists in a "critical length", the size of the average Sensitive Area. For most tube electronics this is about an inch. So 2 full twists per inch might be a goal. However that is awful tight for some wire, and lesser twists seem to work fine in many cases.
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Thanks for the pointers PRR. My issues aren't so much with getting the wires twisted as they are in making sure the twisting stays exact right up to the socket and keeping my runs neat and staying-put, but the latter is probably easily solved with solid-core wire.
The theory as I've read it is that twisting is actually done because the cancelling-effect occurs when the two wires are consistently equidistant apart - which is exactly what the twisting accomplishes - and is also exactly what zip cord accomplishes - the two wires are always held the same distance apart by the insulation.
My thinking is, if the zip cord does exactly what twisting is supposed to accomplish, why go through all that trouble? I know there are quite a few builders who are doing this with great success but I just couldn't find any pics of how they actually implemented it.
Of course, like you said, there are several other things that can cause hum and I am still new at learning all of those tricks too. I may just end up abandoning my push-pull reverb quest and build the ReVibe unit as seen here on this site. I have my PP reverb unit sounding pretty good, just needs a little tweaking to get it "right" and one of the tweaks is getting rid of the hum, which I know can be an issue with stand-alone reverb units.
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> two wires are consistently equidistant apart
That has little effect.
You want them consistently equidistant from the sensitive audio nodes.
Imagine a dog who is spooked by solid white or black, but mellow about gray. You have to run white and black hoses past his dog-house. If you lay them side-by-side, he will see the black (or the white) and be upset. If you twist them, the white and black seem to merge. Further if he does not see sharply, then a twist-length smaller than his blur circle will "be" gray for practical purpose.
Is this a super high gain amp? a recording amp? Everyday amps have been built with quite "poor" heater detailing and paid the rent. Super high gain in live venues often gets by--- stay loud!! Recording amps just might profit from DC heat, despite the cost and complication.
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As Always...multiple theories.
I never thought there was anything magical about twisting (although that is what I do).
Flat "zip cord" should work just as well.
Look at a Soldano...heaters straight as an arrow and 1/4" apart.
Heaters seem to be like grounding schemes. There are many different ways to do it, and they are all used to success with one builder or another. :dontknow:
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Look at a Soldano...heaters straight as an arrow and 1/4" apart.
which is consistent with the theory of the twisting and zip cord... the lines of opposite polarity are kept equidistant from one another, whether that's 1/64" or 1/4" doesn't matter.
But yeah, as they say there's more than one way to skin a cat. In my research on this in the end most people admit that they twist because that's the way they were told to do it and it looks cool if you choose your two favorite colors of wire.
In this specific instance, it's a stand-alone push-pull reverb unit so very low gain actually. This probably isn't even the problem, more likely a ground-loop issue. But I saw it somewhere else and thought it would be easier going forward to use zip instead of all the headaches involved with twisting.
Disclaimer: I'm not a physicist... just regurgitating the science I've read elsewhere that makes sense to me, so of course, I wouldn't hold to any of this if it came down to life-or-death. :laugh:
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In hi-fi where the gain is lower, some have used non-twisted wires for the filaments, such as the one shown below, but not sure if it's a good idea for geetar amps though...
(https://lh6.googleusercontent.com/-4wPKlwwVDKg/UmP7DLVu3qI/AAAAAAAARO4/A-ta9r31lns/s800/IMG_8129.jpg)
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Look at a Soldano...heaters straight as an arrow and 1/4" apart.
There's more to that issue. We beat the Soldano heater thing to death in this thread (http://el34world.com/Forum/index.php?topic=17096.msg170440#msg170440).
But yeah, as they say there's more than one way to skin a cat. In my research on this in the end most people admit that they twist because that's the way they were told to do it and it looks cool if you choose your two favorite colors of wire.
As long as you're not too precious about your wiring, do whatever you want. If it hums, power the heaters temporarily from a 6v lantern battery. If the hum goes away, you know you probably have an issue with the heater wiring (or a leaky tube, but save that can o' worms for later).
A lot of things done with regard to audio wiring are more about precautions to head off a possible problem, and could be more excessive than needed. Without a lot of experience, many don't know how their wiring creates problems in their amp. Without the repeatability of p.c. board construction, what worked fine once may not work fine a different time.
Use whatever you want however you want. If it works, you'll have learned something. And if it doesn't work, you'll have learned something.
In hi-fi where the gain is lower, some have used non-twisted wires for the filaments, such as the one shown below ...
See the linked thread above. Those heater runs are well away from anything they could radiate hum to, and those "vulnerable" things are positioned in a way to minimize hum pickup from the heaters.
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Use whatever you want however you want. If it works, you'll have learned something. And if it doesn't work, you'll have learned something.
Good advice there. It's often far less painful to learn from other people's mistakes than your own though. :icon_biggrin:
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Ah, but the painful memories stick with you much longer.
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Per usual.....good info/advice from PBR, Hot BP, et al.
Even a simple question (do you need to twist wires) can involve many variables. I do not think Twisting has ever CAUSED a noise problem...so I just set that as my default. The amps I build/repair are predominately of the hand-wired, eyelet board, turret board variety. I frequently have to route heater wires "here and there".....so twisting always seems the best choice.
I remember the first time I saw an Express with the "lazy loop" method. I thought it was nuts. But, as has been mentioned, it depends on a few other things...surrounding topology for one.
So I twist, but I am interested in other methods that my betters use with success. :worthy1:
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Recently I have been using Teflon coated wire. Due to the thin insulation. This helps get the twisted wires as close together as possible without having to really crank on it to get the tight twist. The closer the two twisted wires are together without touching the better right? Not to mention the heat resistance of the Teflon makes things easier to solder them to the sockets without melting insulation (always a bummer).
I've never tried zip cord though.
Peace, :icon_biggrin:
-Aaron
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The one builder that I know uses/has used zip cord would be Zaphod Phil over on the 18 watt site.
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In hi-fi where the gain is lower, some have used non-twisted wires for the filaments, such as the one shown below, but not sure if it's a good idea for geetar amps though...
(https://lh6.googleusercontent.com/-4wPKlwwVDKg/UmP7DLVu3qI/AAAAAAAARO4/A-ta9r31lns/s800/IMG_8129.jpg)
That is so pretty that I have to say - learn cable lacing. Those zip ties are just awful.
I would care about them if everything else weren't so nice, but if you are going to the trouble of getting all the swag just right....
http://makezine.com/2009/07/28/lost-knowledge-cable-lacing/ (http://makezine.com/2009/07/28/lost-knowledge-cable-lacing/)
http://en.wikipedia.org/wiki/Cable_lacing (http://en.wikipedia.org/wiki/Cable_lacing)
http://www.hnsa.org/doc/cabling/part5.htm (http://www.hnsa.org/doc/cabling/part5.htm)
Gabriel