DIY Transistor Amp Using NVA Boards

For the three and more legged things
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#256 Re: DIY Transistor Amp Using NVA Boards

Post by Nick »

Cressy Snr wrote: Sat Jun 04, 2022 7:39 pm RD said it was capacitive so naturally I simply parrot what I’m told, as you do when you’re an English graduate and he is an engineer. Kimber Kable woven litz speaker cable or that twisted twin plaited CAT5 stuff that used to be popular, he told me would send his amps into paroxysms of terror.
The issue is the woven and twisted bits not the litz.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#257 Re: DIY Transistor Amp Using NVA Boards

Post by jack »

Cressy Snr wrote: Sat Jun 04, 2022 7:39 pm RD said it was capacitive so naturally I simply parrot what I’m told, as you do when you’re an English graduate and he is an engineer. Kimber Kable woven litz speaker cable or that twisted twin plaited CAT5 stuff that used to be popular, he told me would send his amps into paroxysms of terror.
That can only be due to the way the cores are laid and nothing to do with the cores being Litz per se.

The whole thing about using cat5/5e etc. always seems a bit mad. CAT5 cable is designed to minimise common and differential mode interference and is intended to be used with very specific signal levels and connections - the figures quoted for loss, inductance & capacitance are only valid for specific test conditions which are designed to reflect the cable's use for correctly connected and terminated data transmission, not for random thuggery as arbitrarily connected speaker cable terminated with 8 or 4 ohms rather than the correct characteristic impedance of 100 ohms.

Edit: Nick & I seem to be echoing each other...
Vivitur ingenio, caetera mortis erunt
Cressy Snr
Amstrad Tower of Power
Posts: 10552
Joined: Wed May 30, 2007 12:25 am
Location: South Yorks.

#258 Re: DIY Transistor Amp Using NVA Boards

Post by Cressy Snr »

Thanks for enlightening me chaps.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
User avatar
andrew Ivimey
Social Sevices have been notified
Posts: 8307
Joined: Mon Jun 11, 2007 8:33 am
Location: Bedford

#259 Re: DIY Transistor Amp Using NVA Boards

Post by andrew Ivimey »

Well that's telling you isn't it just. And me and anyone else eh! What I enjoyed, a very long time ago, is how much opinion was generated by Cat5 and it went on and on and on and on, onother forums too.

Didn't 'we' agree that with valves it doesn't matter a toss but with fernickety solid state well that was a different ball game( rounders!) Entirely?
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#260 Re: DIY Transistor Amp Using NVA Boards

Post by jack »

Harrrumph! Bah! Humbug !
Vivitur ingenio, caetera mortis erunt
Daniel Quinn
Old Hand
Posts: 859
Joined: Thu Jan 05, 2017 9:19 am

#261 Re: DIY Transistor Amp Using NVA Boards

Post by Daniel Quinn »

I thought litz was woven or twisted ? Litz being a word for woven or twisted .
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#262 Re: DIY Transistor Amp Using NVA Boards

Post by Nick »

Daniel Quinn wrote: Sat Jun 04, 2022 9:39 pm I thought litz was woven or twisted ? Litz being a word for woven or twisted .
It is, its a single wire made up of twisted or woven smaller wire. But as each wire carries the same signal there is no adverse capacitance generated. Its only when you twist or wave two of them together and make then a pair of conductors the problem happens. But the same problem happens irrespective of them being individual litz.

I guess being litz may make it slightly worst as litz has inherently less inductance so once you form a pair and generate the capacitance there is less series inductance to get in the way of the amp wanting to be unstable.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#263 Re: DIY Transistor Amp Using NVA Boards

Post by IslandPink »

One key point about litz is that the individual conductors are insulated from each other, so it behaves very differently from cheap speaker cable with a fuzzy mass of thin conductors all twisted together.
Cat 5 is a handy source of fairly thin conductors, individually insulated with teflon, so it should and does better a lot of other options - whether or not the measured parameters have any relevance to audio.
"Once you find out ... the Circumstances ; then you can go out"
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#264 Re: DIY Transistor Amp Using NVA Boards

Post by jack »

IslandPink wrote: Sun Jun 05, 2022 10:26 pm One key point about litz is that the individual conductors are insulated from each other, so it behaves very differently from cheap speaker cable with a fuzzy mass of thin conductors all twisted together.
The whole point of Litz cable is to reduce skin effect at high frequencies (typically sub 2MHz though). Apart from that, how does it behave "very differently" from "a fuzzy mass of thin connectors all twisted together"? Genuinely interested here. There may be some self-inductance differences, though I'm not sure if there would be and even if there were, how significant that would be. Not sure there's any self-capacitance effects in a Litz wire either as the signals in all the strands are coherent. It's also worth noting that there are loads of different types & configurations of Litz cable - diameter of each strand, type of insulation, number of strands in a wire and whether those strands are split into bundles that are then all twisted into a bigger bundle, whether the strands are woven and how they're woven etc. The term "Litz wire" defines a general concept of cable, not anything specific.
IslandPink wrote: Sun Jun 05, 2022 10:26 pm Cat 5 is a handy source of fairly thin conductors, individually insulated with teflon, so it should and does better a lot of other options - whether or not the measured parameters have any relevance to audio.
"so it should and does better a lot of other options" - why? Fairly sweeping generalisation there...
The individual conductors can be insulated with many different things, not just Teflon/PTFE. The point I was making is that the layup of the pairs in the cable is complex (and not even standardised) and the characteristics of the cable depend on how those cores/pairs are used & terminated. The characteristic impedance of the cables is important, even at audio frequencies.
Last edited by jack on Mon Jun 06, 2022 12:01 am, edited 1 time in total.
Vivitur ingenio, caetera mortis erunt
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#265 Re: DIY Transistor Amp Using NVA Boards

Post by IslandPink »

jack wrote: Sun Jun 05, 2022 11:48 pm The whole point of Litz cable is to reduce skin effect at high frequencies (typically sub 2MHz though). Apart from that, how does it behave "very differently" from "a fuzzy mass of thin connectors all twisted together"? Genuinely interested here. There may be some self-inductance differences, though I'm not sure if there would be and even if there were, how significant that would be. Not sure there's any self-capacitance in a Litz wire either as the signals in all the strands are coherent.
It clearly behaves very differently when you listen to it with well-recorded music in a serious system. Do you have any opinions about HiFi components that are actually from listening, and practical experimentation yourself, or do you just base all of your reactions on what you read in a book or from selected online theory ?
"Once you find out ... the Circumstances ; then you can go out"
User avatar
jack
Thermionic Monk Status
Posts: 5493
Joined: Wed Dec 29, 2010 8:58 pm
Location: ɐılɐɹʇsnɐ oʇ ƃuıʌoɯ ƃuıɹǝpısuoɔ
Contact:

#266 Re: DIY Transistor Amp Using NVA Boards

Post by jack »

IslandPink wrote: Mon Jun 06, 2022 12:00 am
jack wrote: Sun Jun 05, 2022 11:48 pm The whole point of Litz cable is to reduce skin effect at high frequencies (typically sub 2MHz though). Apart from that, how does it behave "very differently" from "a fuzzy mass of thin connectors all twisted together"? Genuinely interested here. There may be some self-inductance differences, though I'm not sure if there would be and even if there were, how significant that would be. Not sure there's any self-capacitance in a Litz wire either as the signals in all the strands are coherent.
It clearly behaves very differently when you listen to it with well-recorded music in a serious system. Do you have any opinions about HiFi components that are actually from listening, and practical experimentation yourself, or do you just base all of your reactions on what you read in a book or from selected online theory ?
Harsh and somewhat patronising ! Not online or books (don't normally need to), except what I was taught and used when doing RF design work (I was at one time a professional EE). And, yes, I've tried CAT5 and Litz wire speaker cables and interconnects, along with RG316 and RG402 with SMA terminations for small-signal interconnects (just because I have it in the lab). And, for me, I heard no significant differences compared with my default 6491X control gear cable for the speakers - this is with a variety of amps, admittedly mostly solid state. I have rolls of Litz wire here from those days, but now it's mainly used for rebuilding the occasional damaged inductor in valve radios. I must say the RG316 and gold-plated SMA connectors do look very cool though; RG402 is just bonkers to work with.

Maybe it's just me. As I've stated several times on this forum when folk have got upset that I ask the question: Why? it's because I'm genuinely interested in what may be causing folk to hear differences. When I used to do blind tests on this sort of stuff, I used to do so with a good friend who was a senior techie in one of the major high-end speaker manufacturers. He would bring a load of wonderful looking cables over (I've still got some) and we'd sit in our listening room and take it in turns to runs or listen to a/b tests. His ears are definitely more subtle and attuned to small differences than mine. The default speakers we were using then were high-end units he bought with him.

Maybe I'm just a pleb, but I won't apologise for asking the questions and there is no intent to traduce the opinions of others. I'm genuinely interested in BOTH qualitative and quantitative input. If someone states that something "behaves very differently", is it unreasonable to ask "Why"?
Vivitur ingenio, caetera mortis erunt
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#267 Re: DIY Transistor Amp Using NVA Boards

Post by IslandPink »

Sorry Nick, I'm not in the best of moods this evening. When you show your mother (on loan from her residential home) old photos from her house , and she says 'I don't know who these little kids are' and you have to explain to her that 'it's me and Louise' ( my sister ) then it puts a damper on the whole weekend away.

If you want me to explain technically why litz of various types always sounds better, it'll take me longer than just giving me the results of my listening experience. It's just that the sonic difference is to me so obvious that it hardly needs debate in my mind.
I have skimmed though a few things that Colin W has written on the SECA forum. Maybe I can understand this properly, and pass this on, with more work.
If you look at it purely from a dB point of view it would hardly seem to matter, what is it ? - -0.1dB at 20kHz ? - but it sounds a whole lot more significant when listening from Vinyl, with a 45 amp on treble, and ribbon tweeters.

Must get to bed.
"Once you find out ... the Circumstances ; then you can go out"
User avatar
izzy wizzy
Old Hand
Posts: 1496
Joined: Fri Nov 02, 2007 7:02 pm
Location: Auckland NZ
Contact:

#268 Re: DIY Transistor Amp Using NVA Boards

Post by izzy wizzy »

Cable whys and wherefores are inherently problematic without the full picture. Drive Z and termination Z for starters and also signal level.

No one would use a microphone cable to drive a speaker nor the other way round. It's an extreme example to make a point.

It's interesting to note that studio stuff is 600R drive and termination mostly maximising power transfer. HiFi is mostly medium drive Z and high termination maximising voltage transfer. Studio stuff is mostly balanced, HiFi mainly unbalanced. Studio stuff may also have galvanic isolation where HiFi stuff rarely does.

Unsurprisingly maybe, that HiFi cabling is a mixed bag and studio stuff not so much. And although it does make a difference, for many the effects may only be minor and so claim "there's no difference". It's hard to weigh up "perspective" in a forum environment.

I've noticed over time, reducing drive Z and lowering termination Z removes cable effects to a place I can't really be bothered.
Daniel Quinn
Old Hand
Posts: 859
Joined: Thu Jan 05, 2017 9:19 am

#269 Re: DIY Transistor Amp Using NVA Boards

Post by Daniel Quinn »

I’m still waiting to hear a difference .
User avatar
Nick
Site Admin
Posts: 15707
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#270 Re: DIY Transistor Amp Using NVA Boards

Post by Nick »

It's interesting to note that studio stuff is 600R drive and termination mostly maximising power transfer
Except they don't actually do that now for audio, its still the written standard, but sources don't have to have transformers matching valve output stages, so low output impedance and high input impedance are more common. Power transfer doesn't matter as the source can push out as much as needed and the load doesn't need any.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
Post Reply