copper foil speaker cables?

[buddam]

Anyone with experience of making these? I recall a discussion in the past but assume it was on the old WAD BB since I can't find it here.

I have 2 alpha-core foil inductors that I've removed from a x-o in order to replace it inside the box & wondered whether to keep the inductors or cut them up for cable. I'd be running them from a KEL84

Cheers

Adrian

[Scottmoose]

You can do it, certainly. But the (slightly tongue in cheek) question is why would you want to?

OK, more practically, Goertz, Townshend and some cable cookbooks swear by flat foil used for cable as it allows hyper-low inductance geometries to be used. Nice in theory -great in fact. A speaker cable in an ideal world would have zero inductance, or at least as close as can be attained. Problem is, as always in this life, we never get something for nothing, and the trade-off is that in most of these cases they need to have a zobel slapped across them, or the high capacitance will cause considerable gain peaking in the frequency domain, while step response in the time domain will also suffer from ringing due to the higher overshoot. I imagine the WD amps will be much more stable than most, considering they've been designed by some of the top people in the audio game, but even they would likely exhibit some undesirable behaviour if attached to a speaker via a very high-capacitance wire.

Two of my favourite cable articles. The first is an objective review of a variety of commercial wire (including a Goertz of the type under discussion), which also quotes sections from the second.
http://www.audioholics.com/reviews/c...iews-faceoff-2
http://sound.westhost.com/cable-z.htm

[buddam]

In answer to your Q Scott, I don't want to any longer. Thanks for saving me from another detour. Cue the music

[Iain123]

Hi Buddam, I have tried copper foil speaker leads and found them very good sounding. I however made them with the foils laid flat with about an inch gap between the two foils. This gives low capacitance. If you build the two foils one on top of the other with a thin dilectric between you will get high capacitance. If you have the foil already why not give it a go. All I used was 2 inch wide masking tape withe the foils stuck along each long edge finished off with a layer of tape over the top. Looks messy, is a pain to do in long lengths but as I said above it does sound good.
iain

[Scottmoose]

Only problem with that is, you get higher inductance, which is depressing. Still, YMMV as ever!

I should perhaps have mentioned the side-by-side approach, but I focused on the face-to-face layout because AFAIK there are only two reasons advanced for using foil for speaker cables. Firstly, to reduce skin effect. But skin effect is effectively irrelevant at audio frequencies -ordinary 12AWG zip wire is only down less than 0.2db at 20KHz into a 2ohm load: http://www.audioholics.com/education...speaker-cables
The other reason I have seen suggested is to allow a geometry that will give near zero inductance, and that's probably not worth the effort given the drawbacks in other areas. So with these in mind, I can't see any real point / advantage. That's just my view though, and perhaps there are other arguments I haven't come across. Always good to learn of new things, and your side-by-side version obviously seemed to suit your system and ears Iain!

Best
Scott

[pre65]

Hi-it would go under the carpet !

High WAF ?

Philip

[david counter]

I seem to remember the last time this was discussed there was some very positive reports from people that had tried it,

[Scottmoose]

I can understand that. Just so long as when you go into it you're intending to use them as tone controls as their electrical propertes are certainly going to affect the performance of the equipent they're connecting together. Nothing wrong with that of course (assuming they don't blow your amp up ). I do it too. I just reckon there are easier ways, with fewer drawbacks, than using ribbon. Whatever works best in a system though -I've used 30AWG magnet wire as speaker cable in the past when I wanted to add some series resistance. Looks a bit odd (frightening?) but does the job. Not many complaints about skin effect either for some reason...

[buddam]

Sorry I missed out on the helpful suggestions. In fact, after Scott's first post I gave up on the idea and restored the foil inductors to my x-os, which I had re-installed inside the cabs but left the inductors out for space reasons. But by hot-melting them into the base of the speakers and then connecting to the x-o board there's just enough room for both. Happy to have used them - a good deal better than the ferric cored inductors they had replaced but which I'd briefly returned to.

Adrian

[Ianm2]

I think capacitive loading is MORE significant in tranny amps with feedback, ie some output stages may go pop, naiming no naims.

however, be interesting to analyse its effect on the output tube loading, and if it would upset the output transformer frequency response/ square wave response, too. ie roll off and ringing

I wonder if it would also cause slew rate limiting/transient intermodulation at hi freqs and powers?

Originally Posted by Scottmoose

I imagine the WD amps will be much more stable than most, considering they've been designed by some of the top people in the audio game[/url]

ummm did you ever see the ringing in the old 300bpp?

http://wduk.worldomain.net/forum/sho...300bpp+ringing

the top transformer designer who did that interstage certainly has some explaining to do, I have contradictory reports as to who designed that amps transformers, and not tim de para., it was either andy grove or sp, and as Mr Grove is still designing WD, it was a poor measured performance, however, due to my limited understanding, it may not be poss. to do a well measuring interstage, but to claim the mantle of one of the top transformer designers ( not AG's own words as far as I can tell, and also to claim that he has taught transformer makers how to wind transformers is a joke, they have been doing that for decades, and I think would resent the implication, but perhaps to wind to his coil geometry, its sematics but important ones, Nick Lucas ( the man who ran down wad, costcutted, and produced compromised designs, then started up another company at the same time under another assumed name, then revealed his own identity)

is responsible for those ridiculous claims btw) and produce that, and other hot buzzing tx's, and humming preii tx's, does beg some answers, and on face value WD does appearing to be doing things better, it would be interesting to know why wads were so sporadic earlier on and what has changed.

so we conclude that the old wads could give problems, and frequently did, so that's either

1/ the designers fault,...improper design...begs the question as to really a top transformer designer, and still designing...or....
2/ the manufacturing fault, didn't do what the designer specified.....so the designer is in the clear...
3/ or the r/d and testing, ....circuit was designed by AG and wad filled in the gaps, which were insufficient

or

4/ end user assembly, which no doubt at times has been compromised, but I don't thnk you can blame everything on the assembler, so that either leaves wad/AG/maker culpable.

so one of those areas at least is deficient

now it sounds like a witch hunt but its not, I am just seeking an explanation for the previous problems

such suspicions and rumours will persist and possibly even taint WD until the answers are known as to why some wad amps gave such problems, and what has changed to eliminate them, sadly

there are 2 final explanation which are undesirable in that it concludes that

1/ valve amps are inherently prone to random problems no matter how good the designer/r and d/ parts maker/ final build is.

2/ they were designed cheaply, too cheaply,and you can't get owt for nowt.

the recent problems some have had with kel84 suggests that the problems haven't totally been eliminated, which MAY point towards the latter 1/ explanation, however, as many of the previous elements are common such suspicions about all the factors remain

as it happens, I believe in Andy Grove to some extent, mind you, not sure why I should if previous efforts have been poor, and he takes responsibility for that, in the absence of any other information, being talked up so high is no good if practical results are poor, but would still like to know why the interstage pp was so poor, and the preii outputs, too.

actually, I take back the comments about the ringing, it was only on feedback it was worrying, but the problems otherwise are still present, now it MAY well be largely down to user build, limited readying for market, so apart from a few hot buzzing tx's and those awful preii ones, AG is in the clear, and random problems