TBH I couldn't be bothered to write out a load of math as I'm on a laptop at the moment, & assumed that most people would realise from my remarks about voltage drop & the necessity of varying gauge depending on the components that there is a little more to it than purely the resistance of the wire.
hermanv said:
We have a variable transconductance amp in house that lets us dial in the damping from close to zero up to practically infinity. Where it works best depends on he speaker/Cable hooked to it. Most speakers around here, prefer a low damping factor -- often less than 1.
dave
Interesting. The physics of dynamic speaker cone movement favor a design where the cone stops moving more or less instantly when the signal disappears. This is usually accomplished with a high damping factor.planet10 said:
Of course it is dangerous to generalize, I haven't heard your system or your speakers, but good advice for others would be to stick with mainstream technology until the skills are developed to allow consideration of non-standard technologies.
For example there are SET amplifiers, they will usually measure quite poorly and on the whole are inaccurate even though many audiophiles do very much like the sound.
Hermany, you also need to consider the effect of a particular damping factor where the impedance of a particular driver changes with frequency.
It can be used to even out frequency response.
Using a thin cable is a "nicer" solution than adding a resistor.
It isn't a non-standard technology It is uncommon from a particular point of view. Just look at the difference between American and Italian Super-cars. They do things in radically different ways. Which is the "non-standard" technology?
As I said earlier in the thread, If it's cheap try it out and see if you like it. But money is better spent on decent drivers and amplifiers.
It can be used to even out frequency response.
Using a thin cable is a "nicer" solution than adding a resistor.
It isn't a non-standard technology It is uncommon from a particular point of view. Just look at the difference between American and Italian Super-cars. They do things in radically different ways. Which is the "non-standard" technology?
As I said earlier in the thread, If it's cheap try it out and see if you like it. But money is better spent on decent drivers and amplifiers.
Given the extemely well damped nature of many FR drivers, a low output impedance amp. is not automatically a good idea, as without additional Eq (by whatever means you happen to prefer) it can do nothing to compensate for this. That's one of the reasons low DF amplifiers are often prefered by many people, be they SS or valve based. A transconductance / current source isn't exactly mainstream, or suitable for most multiways, but it's certainly not 'non-standard technology' either -Nelson Pass's First Watt amps anyone? http://www.firstwatt.com/downloads/cs-amps-speakers.pdf Or the Zen amps they are decended from? http://www.passdiy.com/articles.htm
Back with wire, a few years back there was a bit of a fad for using highly resistive speaker cable. Assuming some resistance is required to get the driver-amplifier interface optimised, there are probably some benefits to using a resistive piece of wire (providing they aren't swamped by termination losses) in the mids & HF. The LF is a different matter of course. YMMV.
Back with wire, a few years back there was a bit of a fad for using highly resistive speaker cable. Assuming some resistance is required to get the driver-amplifier interface optimised, there are probably some benefits to using a resistive piece of wire (providing they aren't swamped by termination losses) in the mids & HF. The LF is a different matter of course. YMMV.
Many of the earlier very high or ultra high damping factor amplifiers accomplished this by having a large amount of global feedback.Scottmoose said:
Now that some of the negative side effects of high global feedback are better understood, is it possible that your preference for low damping factor amplifiers is due to a preference for low global feedback amplifiers?
To the best of my knowledge all newer Nelson Pass designs have low output impedance and a moderate damping factor. For example the X250.5 has a rated damping factor of 250 into 8 Ohms. Note that Nelson recommends large gauge and short speaker cables.
As is often true, there is not one "correct" answer. Many amplification solutions have been found and all of them perform reasonably well if the design is well executed. Perhaps my use of the words "non-standard" was poorly chosen. Current sources or transconductance amplifiers have indeed been around a long time even if many drivers will not do well due to an impedance curve that is anything but flat. Still, if you make a list of commercial audiophile amplifier suppliers most will be voltage sources.
hermanv said:
The amplifier should not be considered separately from the speaker. The wire, amplifier & cable form a system -- an interactive one -- particulaerily if the amplifier has feedback.
In practise, considering a system, the best that can be done as far as damping is concerned is about 50.
The transconductance amplifier does have feedback, and sounds quite good... not as good as the little PP Class A tube amplifier, but it does put out significantly more power.
dave
hermanv said:
Whoa, that'd be about 315 feet of my #12/2. The wire itself is is gonna run about an ohm...sheesh.
Cheers, John
ps...my double lincoln...😉
I'll chip in my vote for Canare 4S11. Nice stuff, cheap, and easy to work with. Those are the main reasons I like it.
I look at RLC parameters (all that really matters at audio frequencies, IMO). The Canare is a starquad geometry (good for low EMI / radiation), and delivers both low L and C, which is what I look for. R is less important, but low is good. If I need higher R for some reason, I'll use a tube amp, add a discrete resistor to the speaker crossover or use a higher ESR inductor, etc. The wire dielectric is XLPE, which doesn't shrink / melt / stink when you solder. It's nice and flexible, limp, and with a nylon braid cover, it looks very smart. It sounds a little better to me than the cat5 I had used for several years prior - 4 parallel runs (16 pairs), solids and stripes separated at the ends - waaaay too much work to assemble. It could just be that my cat 5 cables were old when I swapped them out, and that was the source of the difference (don't know & don't care - I won't be putting in the time to try building another set of cat 5 cables when I can just order up some nice pre-made cable).
I like the Cardas spades (their low-end ones, GRS-R). Nice construction, high quality platings, and reasonably affordable. I refuse to pay the outrageous prices often quoted for connectors (especially binding posts like WBT, Furutech, and the most offensive of all, Eichmann - W.T.F. they want how much for that cheap piece of plastic with hardly any metal ??!?!?)
BTW - I just ordered 50ft. of Canare 4S8, a lighter guage wire than the 4S11. I don't need 50ft. but that was the minimum order qty. If anyone wants to split it with me, send me a PM. I think it was $0.55/ft + shipping.
I look at RLC parameters (all that really matters at audio frequencies, IMO). The Canare is a starquad geometry (good for low EMI / radiation), and delivers both low L and C, which is what I look for. R is less important, but low is good. If I need higher R for some reason, I'll use a tube amp, add a discrete resistor to the speaker crossover or use a higher ESR inductor, etc. The wire dielectric is XLPE, which doesn't shrink / melt / stink when you solder. It's nice and flexible, limp, and with a nylon braid cover, it looks very smart. It sounds a little better to me than the cat5 I had used for several years prior - 4 parallel runs (16 pairs), solids and stripes separated at the ends - waaaay too much work to assemble. It could just be that my cat 5 cables were old when I swapped them out, and that was the source of the difference (don't know & don't care - I won't be putting in the time to try building another set of cat 5 cables when I can just order up some nice pre-made cable).
I like the Cardas spades (their low-end ones, GRS-R). Nice construction, high quality platings, and reasonably affordable. I refuse to pay the outrageous prices often quoted for connectors (especially binding posts like WBT, Furutech, and the most offensive of all, Eichmann - W.T.F. they want how much for that cheap piece of plastic with hardly any metal ??!?!?)
BTW - I just ordered 50ft. of Canare 4S8, a lighter guage wire than the 4S11. I don't need 50ft. but that was the minimum order qty. If anyone wants to split it with me, send me a PM. I think it was $0.55/ft + shipping.
hermanv said:
Not really. I didn't say I prefer a low DF amp. As Dave mentions above, amplifier wire & speaker are a system; I consider each as a part thereof. Ergo, I want an amplifier that will work well with the driver I'm using. If it's a very low Q unit (i.e. well damped) then an amplifier with a high output impedance will help in compensating for that if (if) no other form of correction is used. Conversely, something with a lower output impedance will typically be preferable for a driver with less motor power / or which is less inherently well damped (they generally go hand in hand, but it's not an invariable rule).
hermanv said:
You're talking about Pass Labs equipment. The Pass DIY designs which have appeared since ~1994 are rather different, and the First Watt amplifiers, which are very recent (the F2 emerged in 2005) are even more so. The first two FW amps (FW is a kitchen-table company by Nelson, selling just 100 of each amp, handbuilt by himself, but also with schematics available to DIYers in the vein of his preceeding Zen amps), the F1 and F2 are transconductance amplifiers, specifically intended for use with FR drivers. The F3 is a voltage source, but with a very mild DF. The F4 is more of a buffer-stage, and the F5... well, it's different. 😉
As it happens, one of the reasons I'm not fooling with cables much (other than the fact that life is far too short and people make them far more complicated than they need to be) is that as I own an F2, I don't really need to, because current source amps, as Nelson points out, mostly 'ignore the impedances in series with the circuit, the resistance and inductance of the wire and voice coil and the back electromotive force produced by the cone motion.' This applies a little more to the F1 than the F2 unless the latter is modified, but it still largely holds good.
Indeed, and I completely agree with you that there is never one single answer. However -this is the FR (driver) forum, so I'm writing from the POV of FR drivers. I've have something different to say in the main loudspeakers forum, for example. A current source, as I noted before, is not going to be of much use for most loudspeakers (and on top of the issue you rightly mention, you'd need to completely change the XO topology) but they can have their uses, and one is for single-driver systems, which is specifically what Nelson intended the F1 & F2 for. They're amps for tweakers & users of some FR drivers, rather than the majority of the hifi fraternity.
I know this has gone arguably to the fringes of the topic, but it's related, and interesting, as the interaction of driver and amplifier, despite being arguably the most important thing for the design and / or selection of a speaker wire, is often forgotten. So I think it's a useful / valid discussion to have here.
hifiZen said:I like the Cardas spades (their low-end ones, GRS-R). Nice construction, high quality platings, and reasonably affordable. I refuse to pay the outrageous prices often quoted for connectors (especially binding posts like WBT, Furutech, and the most offensive of all, Eichmann - W.T.F. they want how much for that cheap piece of plastic with hardly any metal ??!?!?)
Now that's an interestion point: connections. And their losses. I still maintain that you might have theoretically the best optimised amp-wire-driver system, but you can potetially loose out through termination losses. I prefer cold-weld / crimping whenever possible, although I don't just go for one run from amp to driver with no other connections. Probably shoud TBH, but I like the convenience of bananas (and they're probably the worst, not that spades are a whole lot better). Some of the prices asked are outrageous, but it's worth looking at how they make a contact -some might be pretty decent & it'd be worth scouting around for clones. I haven't looked at any for a while.
Scottmoose: While the issue of damping factor and current sources are different for FR drivers, the few I've looked at did not have very flat impedance curves especially near their frequency extremes.
I agree that a perfectly good design can be made if the amplifier and driver is created as a package. For example current feedback instead of voltage feedback can linearize driver output power vs a constant voltage variable frequency input. Unfortunately many (most?) audiophiles tend to buy the speaker and amplifier as separate components, negating that advantage.
Jneutron: Some cable advocates are pushing for 22 or 24 AWG wire, in this case the length for a given inductance is quite different. I agree however that 63 uH is not reasonable and only used that value to match the 0.08 Oms (also arbitrary). 10 milliOhm and 2.5 uH is more reasonable or likely.
hifiZen: Better lugs often come with palladium, iridium or rhodium plating, all of these have better corrosion resistance than copper. If you couple this with a contact pressure usually higher than can be achieved with bananas it makes lugs the better answer in my opinion.
I agree that a perfectly good design can be made if the amplifier and driver is created as a package. For example current feedback instead of voltage feedback can linearize driver output power vs a constant voltage variable frequency input. Unfortunately many (most?) audiophiles tend to buy the speaker and amplifier as separate components, negating that advantage.
Jneutron: Some cable advocates are pushing for 22 or 24 AWG wire, in this case the length for a given inductance is quite different. I agree however that 63 uH is not reasonable and only used that value to match the 0.08 Oms (also arbitrary). 10 milliOhm and 2.5 uH is more reasonable or likely.
hifiZen: Better lugs often come with palladium, iridium or rhodium plating, all of these have better corrosion resistance than copper. If you couple this with a contact pressure usually higher than can be achieved with bananas it makes lugs the better answer in my opinion.
Scottmoose said:
If you are going to use spades you might as well use bare wire.
No terminals is by far the best, but if you swap things in & out as much as i do, a good dual banana is hard to live without. So much so, that one of my pet peeves are when the posts don't have industry standard 3/4" spacing.
dave
hermanv said:
Yes, but this is DIY. So we are in a position to easily select our components (including the wire) to best complement each other to form a cohesive system, which from my POV is the entire point of this discussion / thread. A hifi rig is a system, not a collection of disparate parts. And as I said before, I'm writing from the POV of this forum, not for wider matters & certainly not for the majority of commercial hifi as it exists today, which, if I'm honest, I couldn't care less about.
Re transconductance amplifiers, have you read Nelson's papers which I linked to yet?
Scottmoose said:
Wholeheartedly agreed on all of the above. Although my personal preference is to try and make the wire as small a factor as possible, and design the system interaction (damping factor, frequency response shaping) into the amp & speakers.
Raj1 said:
While we're on this topic, let me throw a few controversial bones to the wolves... 😀
Over the years, I've discovered in the process of building and testing prototype circuits on the bench, it is amazing what kind of sound can be produced with lashed-up circuits using such humble construction techniques as the prototyping plugboard, and wired up with the cheapest old holding-on-by-the-last-strand alligator jumpers in the junk drawer. Imagine a circuit that looks like the tangled mess on the front cover of one of Bob Pease's books. More than a few times I've experienced bliss / goose bumps listening to such a prototype, with all these poor quality wire and connections. Yet the final product, built with fancy teflon / silver wire and soldered connections, sounds about the same... some times a little better, sometimes not quite as good(!). Perhaps part of it is psychoacoustic... the anticipation and excitement of listening to a new circuit of your making for the first time. But the experience has nevertheless left me very skeptical of the whole cult of wire-and-dielectric as well. Certainly, there are places where it matters - dielectric absorption, triboelectricity, piezoelectricity, and other forms of microphonics, inductive and capacitive parasitics, skin effect, etc. But it must all be taken in context. There is no law of physics which says that teflon / silver is always superior.
Now, of course I still use high quality wire... why? Mostly because it is easier to work with and lasts a long time. Open up some old test equipment, and wherever you see teflon wire, it looks literally brand spanking new! The other stuff is yellowed and cracking, oxidized. Teflon and XLPE don't shrink and burn when you're soldering, the way PVC does (yuk - I'm not worried about lead poisoning, I'm worried about inhaling burnt PVC fumes!). If you're soldering in a tight spot, and the barrel of your iron brushes up against a teflon wire - you won't even notice it. Zero damage done.
Another one I don't subscribe to... this hypersensitivity to magnetic materials. Bah. Why don't transformers (the ultimate coupling of magnetic materials and signal conductors) sound like absolute hell then, hmmm? Smells to me like another line of BS used to sell more expensive parts. Admittedly, I've done few experiments to test this theory, as it just doesn't seem worth the effort. I'm getting excellent results without worrying about this. Application of a little common sense and some sound engineering know-how can go a long way in predicting what will or won't corrupt a signal. Yes, I can imagine some hypothetical physical effects (magnetic field concentration & EMI, shallower skin depth) which might perturb a signal. The influence of those effects is somewhat uncertain (though probably not too hard to measure, if someone would put in the effort to do so), but certainly insufficient in my judgment to justify this whole paranoia about banishing magnetic materials. Again, common sense in where and why particular materials are applied is all it takes to avoid the potential trouble spots.
Here's one last faux-pas to toss into the mix, since we're on the subject of speaker cables and connectors... lately I've been testing out (*gasp*!) Neutrik Speakons here and there. And you know what, I really like these connectors a lot. Neutrik makes a 4-pole connector which I've used on my JX92S / G2Si speakers, so that I can have an external crossover which is easy to detach and change out. So they aren't the prettiest things (not ugly to me though - there are some very expensive connectors which I think are ugly), but the construction quality is good, the contacts are quality silver plated copper / brass, an they're easy to install. They get the job done well, the cost is appropriate for what they are, and they're built to take the abuses of road-shows and other pro applications. Here again, I have found they do not audibly degrade the sound vs. a soldered connection. Maybe when they start to wear out, I'll spring the $5 to install a fresh set...
Have I tossed enough fuel on the fire?? 😀
Have at it!
planet10 said:
Stepping down off the soapbox...
Another connector I really like is the Cardas "patented" spade post... the one with the knob that tightens down on two terminals at once. These are just great, and if you are swapping things around a lot, I think this is the best system of all. It makes a nice tight connection without any friction or scraping between contacts to cause wear. Just as quick as bananas, and you get a more positive lock - a banana can come out with a tug on the cable, these will stay tightly in place.
Not at all. Some of the best sounding (well, not sounding at all) amplifiers I've ever (never?) heard were breadboard specials, with many of their connections being spectacularly cheap crocodile clips.
Same here, whenever possible. That's why I keep going on about system matching.
Context is king. For e.g., despite what the cable companies claim, almost none of these have any relevance for audio frequencies, especially for speaker cables (or line level interconnects come to that). Internal to an amp = not a while lot more. Triboelectricity can be a problem for some combinations (silver & teflon being an obvious example) if they're likely to be in an area where mechanical vibrations are going to get into the wire, but that's more an issue for mics. than anything in the reproduction chain.
Ah yes, I remember the ones you mean. They look pretty decent (haven't used them myself). Main problem with spades that I remember is the contact area, or lack thereof, in most cases. These should do a little better.
hermanv said:
Yes, Cardas does sell bare copper posts and spades. In theory if you take careful care of those (regular cleaning and application of anti-oxidation agents - hopefully you don't live some place too humid), they will be fine for a long time, but I prefer something more corrosion resistant. The ones I was talking about earlier (GRS-R, CPBP-CRS ... see attached pictures) are available with my preferred plating, Rhodium over Silver. Highly conductive, and highly corrosion resistant. The base metal is solid copper on both, and the platings are of very high quality.
With the spades, I usually discard the little brass tube (maybe it's supposed to be used as a crimp ferrule?) and just solder it on. After soldering, a little clear nail polish to seal off the stripped end of the wire should help prevent or at least slow down long-term oxidation of the copper wire. I finish off with heat-shrink and expandable braid tubing for cosmetics.
Cardas represents about the upper limit of what I'm willing to spend on connectors (IMO they're over the line on hookup wire, though). At least the prices are somewhat rational - high quality metals and platings, nice machining, good design, and a fair retail markup... I can accept that - if you really want a nice connector for that special project, you're getting something for your money. If you don't want to spend so much, there are cheaper options which will work just as well - some of the Vampire and Neutrik stuff. It's the blatant profiteering of some of the other guys that really turns me away. But they must be making a killing, or they wouldn't remain in business, continually jacking the prices higher and higher... ?
I think I agree on your point about contact pressure. I trust a spade more than a banana for a good electrical connection, although the bananas are hard to beat for convenience.
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