vacuum_tubes
pfm Member
Yes I could.
Mains IEC Connectors, I never realised !!
- Thread starter IWC Doppel
- Start date
Yes I could.
It does have a low impedance and that helps with ESR. Resistance works in series, so the idea of the fuse being the only bottleneck is erroneous. There is resistance in the whole cable run and using lower impedance wires where possible is going to bring it down overall. My mains conditioner has 6 pieces of 1mm thick wire soldered over the fuse in the plug and a 100A RCCB where the cable goes into the box to maintain safety. The result is a much lower ESR from the consumer unit to the transformers inside my gear.
Think of it like breathing. If you breathe pure oxygen and get on a spin bike you can go phenomenally fast with no pain in your legs for quite a long time. This pure oxygen is like a very low ESR in a cable run.
Have you tried breathing through a long thin snorkel? It's very hard and you won't swim very fast at all, but a wider tube of the same length is less so. Again the wider snorkel tube is analogous to a lower ESR run from the consumer unit to your gear. The better the conductors at every stage of the chain, the better the dynamics and the higher the power to noise ratio. With a thin fuse in the way the rest of it needs to be optimised.
martin clark
pinko bodger
Then again it is worth understanding what transformers do.
Most people think of these as providing the needed voltage transformation; and they do - but that also means impedance transformation is ongoing. A 'perfect' step-down transformer transforms the supply impedance by 1/(voltage ratio ^2).
So - if you have say a 150W ohm amp, and it is running off a 240: 2x 40Vac type transformer - the supply impedance on the AC side is divided by about 36 on the output side. That swamps the contributions of even modest mains AC wiring, fuses, the distance your CU is from your mains incomer etc. - to the extent that actually it's the transformer secondary winding resistance(s) that dominate, then the primary winding(s) - even these could 10+ ohms for even rather a large transformer - so everything prior to that on the Mains side, is way down in the weeds.
I'm not decrying what people choose for themselves, at all; just hoping to add some perspective.
Most people think of these as providing the needed voltage transformation; and they do - but that also means impedance transformation is ongoing. A 'perfect' step-down transformer transforms the supply impedance by 1/(voltage ratio ^2).
So - if you have say a 150W ohm amp, and it is running off a 240: 2x 40Vac type transformer - the supply impedance on the AC side is divided by about 36 on the output side. That swamps the contributions of even modest mains AC wiring, fuses, the distance your CU is from your mains incomer etc. - to the extent that actually it's the transformer secondary winding resistance(s) that dominate, then the primary winding(s) - even these could 10+ ohms for even rather a large transformer - so everything prior to that on the Mains side, is way down in the weeds.
I'm not decrying what people choose for themselves, at all; just hoping to add some perspective.
So why does it still make a difference?
martin clark
pinko bodger
Good question!
I go with @S-Man 's post earlier - eliminating common impedances (i.e minimising differentials of voltage from any circulating leakage current on the mains earth bonds, is probably most significant; especially if a system contains both 'traditional' linear, and SMPS PSUs.
Which is why the 'hydra ' approach works so well, even for multiple boxes (and esp for complex systems - unless, you need potentially more power than one wall-plate can provide. Also, I think, why tight pin fit on the input IECs matters. Many IEC plugs are lousy for this given the horrid, low-tension inherent design: it matters, esp. on the E pin. Moulded Volex cables I've found good&consistent - hence my earlier suggestion for a really-cheap trial. Schurter rewire-able get mentioned sometimes - but they aren't very good at all IME: same-old IEC hair-clip, low spring tension.
I go with @S-Man 's post earlier - eliminating common impedances (i.e minimising differentials of voltage from any circulating leakage current on the mains earth bonds, is probably most significant; especially if a system contains both 'traditional' linear, and SMPS PSUs.
Which is why the 'hydra ' approach works so well, even for multiple boxes (and esp for complex systems - unless, you need potentially more power than one wall-plate can provide. Also, I think, why tight pin fit on the input IECs matters. Many IEC plugs are lousy for this given the horrid, low-tension inherent design: it matters, esp. on the E pin. Moulded Volex cables I've found good&consistent - hence my earlier suggestion for a really-cheap trial. Schurter rewire-able get mentioned sometimes - but they aren't very good at all IME: same-old IEC hair-clip, low spring tension.
John Phillips
pfm Member
It really shouldn't technically. But people are people. A step-down power supply transformer renders a microscopic view applied to impedance on the primary-side of a power supply all but irrelevant.
Even in a really big solid-state power amplifier with a 5:1 step-down mains transformer (it's greater for lower power) the primary-side impedances people conjure with are in effect transformed on the secondary side to 1/25 of their primary-side value. You need then to look at that in the context of the actual secondary-side impedances in the amplifier circuit where the effect of the primary-side impedances have normally become too tiny to be significant.
You need to take a macroscopic view of design to see what really matters and what can be ignored. Unfortunately people who have never designed things get tempted by marketing to look at tiny all-but-irrelevant issues and believe that they matter. So they do matter. That's the way people work if you have observed real life.
gez
pfm Member
I live in a house that was originally built around the turn of the century (and no I don't mean the century we're currently in), and was converted in to flats in the early 70's. As far as I know all the wiring is from that time*, so even if I were to connect my integrated amplifier rated at 2x250w in to the wall socket with a cable and plugs made of imaginarium which had zero resistance and infintite current handling capablity it would make zero difference to what my amplifier would see.
*Though the consumer unit is clearly more modern as I don't believe they had RCD based units back that early.(?)
Edited to add: a bit of research shows that my consumer unit very likely does date from the early 70's.
*Though the consumer unit is clearly more modern as I don't believe they had RCD based units back that early.(?)
Edited to add: a bit of research shows that my consumer unit very likely does date from the early 70's.
Somafunk
pfm Member
gingermrkettle
Deep vein trombonist
Or use Powercons.
Somafunk
pfm Member
I guess you are not aware of BS 7671
S-Man
StrivingON
Spot on!
I also don’t like Schurter IECs. I have no idea how they got their reputation.
Taking things a step further I have wondered if all my boxes should be joined together with braided earth straps, perhaps using the preamp (active crossover in my case) as the star point?
Not sure what that has to do with it. I just added a direct earth line with lower resistance that isn't polluted by the other stuff in my house, using the same rod and cabling that certified sparkies use. My stereo is so good that my 84 year old dad could instantly tell that I changed a USB cable. It's that way because I take every aspect of the chain seriously. You lot are going to have kittens when i post pictures of the finished conditioner
martin clark
pinko bodger
@S-Man
Erm - doesn't that just risk creating, as much as resolving, stray earth-bond currents..? There is a difference between inter-chassis potential, earth leakage, and CM shite from some stray PSU. So at least three different strands of corruption..?!
I'd rather define where such can flow.
Anyway - I had that same thought years ago, and set-about measuring differences with a DVM - since even a cheap dvm has input impedance in the 10^8ohm range, measuring interchassis-voltages soon shows if there's an issue. Bought better DVM..
For my own pile - I'm at limit of resolution , 1uV +/- a count or two (or whatever it is in the manual), and thats just.so.far into the long grass - its beyond-irrelevant for audio. That with a simple DIY hydra, 7 boxes (all linear supplies); and the ESLs powered (pair of mains leads, no mains earth connection on Quads) via another plugtop into the other socket on a standard UK switched dual-outlet faceplate.
Then again - the ESLs by design , are transformer -isolated from the rest of the sistem, in two senses. Or , maybe I'm just lucky.
Erm - doesn't that just risk creating, as much as resolving, stray earth-bond currents..? There is a difference between inter-chassis potential, earth leakage, and CM shite from some stray PSU. So at least three different strands of corruption..?!
I'd rather define where such can flow.
Anyway - I had that same thought years ago, and set-about measuring differences with a DVM - since even a cheap dvm has input impedance in the 10^8ohm range, measuring interchassis-voltages soon shows if there's an issue. Bought better DVM..
For my own pile - I'm at limit of resolution , 1uV +/- a count or two (or whatever it is in the manual), and thats just.so.far into the long grass - its beyond-irrelevant for audio. That with a simple DIY hydra, 7 boxes (all linear supplies); and the ESLs powered (pair of mains leads, no mains earth connection on Quads) via another plugtop into the other socket on a standard UK switched dual-outlet faceplate.
Then again - the ESLs by design , are transformer -isolated from the rest of the sistem, in two senses. Or , maybe I'm just lucky.
martin clark
pinko bodger
banging-in such a spike if you live anywhere near a 'town ' supply with conventional PME, has added SQRT[F'all] in terms of lowered impedance; a 4' spike is not a low-resistance Mains-Earth Bond, and - adding one to a conventional TN-S -etc system - is not trivial.Not sure what that has to do with it. I just added a direct earth line with lower resistance that isn't polluted by the other stuff in my house, using the same rod and cabling that certified sparkies use. My stereo is so good that my 84 year old dad could instantly tell that I changed a USB cable. It's that way because I take every aspect of the chain seriously. You lot are going to have kittens when i post pictures of the finished conditioner
misterdog
Not the canine kind
It does to the electrons, they have feelings too.
misterdog
Not the canine kind
Does your system sound at it's best when it is raining really hard ?
Not until I installed 34 tellurium plated umbrellas all over the roof.
Beobloke
pfm Member
But the fuse is NOT a bottleneck, therefore neither is the cable. The difference in resistance between a 13A Cooper Bussmann fuse and a 3A one is a smidge over 39milliOhms which will have absolutely no effect on the power transfer of 230Vac or the sound.
In fact, if 39mOhms really does have an adverse effect on a PSU then it’s horrendously badly designed!
As to your pieces of 1mm wire where a fuse should be - so you’ve left the cable with no protection? More importantly, does your house insurance provider know?