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In Reply to: OTL rewiring... posted by boll001@pol-it.org on February 1, 2005 at 05:48:28:
There are no "correct" answers to your questions. While I do hear very subtle differences between silver and copper chassis wires, either one can give you superb results. If you had me at gunpoint, I might say that silver wire tends to emphasize slightly the upper mids and treble, but not in a bad or irritating way. There's just a little more "shimmer". (Sorry for the arcane English word; I don't know the equivalent word in Italian.) Copper might be a little richer in the mid-bass and bass vs silver. But notice how my desciptions are suggested by the color and texture of silver vs copper. I think we are highly influenced by color in our thinking about sonic qualities. In other words, I may be imagining these differences, but many others have similar opinions of silver vs copper.As for "diameter", it should be determined by function. For wires carrying high amperage, e.g., wires to and from the power supply, you want the wire to be substantial enough so that it does not heat up noticeably, i.e., you want the resistance per foot to be as low as possible. In addition, I prefer solid core vs stranded wire, but it's not so important for power supply purposes. For wires carrying the audio signal, I firmly believe in using the narrowest gauge wire possible, and solid core is my preference at all times. For wires carrying high voltage, insulation is necessary and teflon is the current best choice. Vintage amplifier guys like to use organic cloth-insulated wire, too, and I am sure that is good also. Where you can get away with it, no insulation is better than any insulation, but otherwise choose teflon.
None of us buys wire directly from a "manufacturer". In the US, I think most of us use vendors who sponsor the Audio Asylum, like Welbourne Labs or Michael Percy or Handmade. These guys buy wire from suppliers like Cardas, Vampire, Kimber, XLO, etc, who in turn buy wire made by real but unknown manufacturers. Polyurethane-coated, solid core copper magnet wire, available in many diameters (or "gauges") down to at least 26-ga is said to be a great-sounding bargain and is widely available. The 26-ga is probably a great cost-effective choice for signal wire. The polyurethane insulation is much thinner than what can be done with teflon and probably sounds as good or better.
Follow Ups:
Thank a lot Lew for your kind and complete reply.
Let me put some questions, consider me a newbie in this field, I love music and hihi I own eras to hear but I'm not able to solder anything....
1) do you think that buying solid core silver (I have found good prices in GERMANY http://www.jacmusic.com TAKE A LOOK) I have to buy different sizie of wire or can I buy only one type to br used for all the connections of the OTLs?
2) in this second case my choise could be Solid-Silver-15 (diameter=1.5mm / surface= 1,76 mm©˜ / AWG15) do you agree?
3) the retailer offer also:
Solid-Silver-04 (diameter=0.4mm / surface= 0,13mm©˜ / AWG26)
Solid-Silver-08 (diameter=0.8m / surface= 0,5mm©˜ / AWG20)
Solid-Silver-12 (diameter=1.2mm / surface= 1,13mm©˜ / AWG17)
is iy necessary for me ti buy some of there different cables?
4) I can easily find in Italy teflon isolation cable is this the solution?
let me know
best from the early night of Genoa, Italy
Francesco
Simple answer: AWG15 is fine for the power supply. I would use AWG26 for the signal wire. If the wire is sold without insulation, just buy some teflon tubing of the appropriate internal diameter(s), and you are in business. But you are not yet in business, if you don't know how to solder. If that is the case, find a professional or advanced amateur who can teach you proper techniques and safety rules. You will also want a good volt-ohm-amp meter, and you will need a solder gun and solder. I recommend a "solder station", which is a set up where you can set the temperature of the solder gun and it is electronically stabilized.
dera Lew IT IS EXACTLY what I'll do:
a professional
a solder station
a good amp meter
At the moment I'm trying to arrange with an italian manifacturer for an more good price of the solid core.
Do you think taht if I buy only one type of silver wire ( the "15") I can use it everywhere also if some thiner wire could be better?
hi from the mediterranean sea
I forgot to add: I personally do NOT like the sound of silver-plated copper wires. I suggest you choose either pure silver or pure copper. But that's just my opinion based on my own listening. Also, Tom has a point. Silver oxide is as good a conductor as is silver, whereas copper oxide is not a good conductor. If you are going to run uninsulated wire, silver is a better choice. On magnet wire, the polyurethane prevents oxidation of the copper.
I agree with Lew's general observations & particularly wrt silver plated copper - it sounds far worse than either type alone.Actually, polyurethane has comparable or worse AC properties than PVC does, fwiw. It's advantage with magnet wire is that it's physically tough and available in high temperature versions. Teflon insulated magnet wire is made - might be a good way to cover your sonic bets.
The advantage of magnet wire is the tiny mass of dielectric. Worse than PVC doesn't matter nearly so much when you have such a small fraction of the amount. Polyurethane and enamels and magnet coatings come in various forms, the problem with teflon is that it is so soft it's prone to cold flow, meaning that pressure can push it out of the way and give you some shorts. Not a good thing by any account. Urethane and polyurethane are much tougher.
Makes me wonder about the use of Zero autotransformers -lots and lots of coated magnet wire, especially in comparison with the minimal lengths inside the amps. If a Zero is used, does it matter what's in the amp?
Hi -The lower stepdown ratio, plus the autoformer configuration does help minimize some of the capacitive effect, but, IMO, it still reintroduces several of the traditional weaknesses of a conventional transformer coupled output to a reduced degree. The question is then whether the reduction in distortion, increase in damping factor and increase in power is worth it for the application at hand.
I've always run my DC coupled OTL direct into the load, but when I was pushing it hard into the nominal 4-5 ohm load of the Basement Blasters a while back, I realized eventually that its distortion was audibly somewhat higher than into an easier load, but in this case, I was able to compensate here by biasing the OTL somewhat farther into Class A operation and accepted the slight loss of power. Of course, unlike some OTLs, mine has a high damping factor, so that frequency response dependencies on the load were not an issue here.
You may be right about polyurethane, but I may be wrong in saying that polyurethane is the coating on magnet wire. It's something made from petroleum, however. By all accounts, the magnet wire sounds excellent, but I have no experience with it.
You don't need to depend merely on my word - look up the electrical properties of polyurethane for yourself - they're mediocre on an audio quality scale and polyurethane is one of the more popular resins used for magnet wire.
I guess I did not make myself clear. I don't disagree with you at all. In fact, when I first heard that the wire is coated with a petroleum derivative, I was skeptical re its use. I am only saying that several DIYers have reported that magnet wire sounds excellent when used as chassis wire and so constitutes a very inexpensive and good choice. I speculate that the reason it may sound good IN SPITE of the polyurethane is that the coating is very thin.
My impression is also that the deleterious effect of mediocre insulation materials is minimized when buffered by a relatively large air gap. Probably the reason that round magnet wire air core inductors don't sound worse than they do are the unavoidable air gaps between turns.
Several years ago, I built a small 2-way speaker system using, in the xover, Solo foil wound inductors having polyester insulating tape (which is a better dielectric than polyurethane or nylon, but not nearly as good as, say polypropylene) and I was disappointed in the relatively strong negative effect the insulating tape had on the SQ (lacking air gaps - it hardly sounded better in this regard than round wire air core inductors). So, as soon as I could, I replaced them all with Goertz foil wound inductors which used polypropylene insulating tape, which sounded substantially smoother and more neutral than the Solos.
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