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Post by pinkie on Nov 4, 2016 16:55:10 GMT
Umm - no. Noise is superimposed on the mains sinewave. It gets through by the PSRR ratio to a much lower level. You can't eliminate it by converting it to DC, it still ends up on the rails. On the rails, we are measuring deviation from flat DC (ripple) Measurable and measured - although there are some limitations to simply measuring that power supply performance - since many good amplifiers effectively integrate their power supply voltage regulation in the amplifier circuitry So the real measure is noise on the amplifier output However, settling for just the power supply, how do you distinguish how much of the ripple is attributable to the basic supply sinewave, and how much is due to "noise" on that. Presumably measure the supply performance fed "clean" mains and "noisy" mains and subtract one from the other. Anybody care to supply data in support of the theory? Using a decent power supply. (Strictly of course PSRR is a measure of the ability to maintain an output voltage given fluctuations in input voltage - in the context of a DC supply - not AC. Rejection of AC is supply ripple voltage rejection ratio (kSVR). ) |
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Post by MartinT on Nov 4, 2016 20:21:50 GMT
The ripple is at 100Hz, so it's easy to filter the noise and measure that alone. Ripple is regular whereas noise is random, so quite different. I learned a lot about it from Paul Hynes, he knows a thing or two about measuring power supply noise and makes some of the quietest ones around.
Oh, and noise can have an intermodulation effect in the audio band, so while it might be up in MHz territory it can still affect the way the amp sounds, not just appear on the output where it's relatively harmless.
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Post by pinkie on Nov 4, 2016 20:52:01 GMT
The output of the amp is the bit we listen to. In this house at least  |
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Post by MikeMusic on Nov 5, 2016 8:34:33 GMT
Mike Wonky is coming here tomorrow. My HiFi uses british fused plugs in a British fused multiway block connected to a radial circuit via a french unfused plug on a french unfused socket. I can run a quality french IEC lead to the adjacent unswitched french socket for one piece of equipment. Which bit of kit do I wire up that way for Kevin and I to hear the difference - pre amp, power amp, CD transport or DAC ? Can't be 100% certain but I'd go for either Power Amp or CD |
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Post by MartinT on Nov 5, 2016 9:12:24 GMT
Agreed.
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Post by pinkie on Nov 5, 2016 10:05:02 GMT
Transport or DAC?
The power amp? You know which one we're talking about. Maybe if there's time
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Post by MikeMusic on Nov 5, 2016 16:25:57 GMT
Power amp doesn't seem logical to me either CD transport. I use a battery for my lovely Caiman DAC |
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Post by pinkie on Nov 5, 2016 17:21:05 GMT
We crossed in the post.We tried the power amp.
Not very hard. but we tried
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Post by MartinT on Nov 5, 2016 22:19:52 GMT
My opinion is that power amps very often show the most sensitivity to mains changes. Counter-intuitive, I know. Or perhaps not, since the current draw is large and bursty.
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Post by Deleted on Nov 6, 2016 0:14:12 GMT
I did not hear any difference between the mains leads.
The system sounded the same to me.
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Post by pinkie on Nov 6, 2016 7:07:14 GMT
Power amp doesn't seem logical to me either CD transport. I use a battery for my lovely Caiman DAC I got to hear Kevin's battery powered Caiman. Again, only briefly, but nice to finally hear it and compare with DaCapo |
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Post by Deleted on Nov 6, 2016 10:34:41 GMT
Power amp doesn't seem logical to me either CD transport. I use a battery for my lovely Caiman DAC I got to hear Kevin's battery powered Caiman. Again, only briefly, but nice to finally hear it and compare with DaCapo How did it compare? |
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Post by pinkie on Nov 6, 2016 11:43:44 GMT
I have moved my reply to PJDowns question to my ex-pat blog - so I thought it was a bit too much drift on Mikes thread |
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Post by MikeMusic on Nov 6, 2016 18:22:50 GMT
Did you compare a 'naked' Schuko to a fused UK plug BTW ?
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Post by pinkie on Nov 6, 2016 19:41:33 GMT
Not sure about naked. The "control" was a UK iec lead with a fuse in it, plugged into a switched junction strip (when the pre-amp switches on, plugged into the master socket, the rest of the sockets in the block are switched on.) This multi way block has a UK plug on it, with a fuse in it, which is plugged into a UK /French adapter plugged into an unswitched socket. We replaced that with a regular unfused French iec lead direct into the adjacent unswitched socket on the same radial. Neither of us could hear any difference |
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Post by MikeMusic on Nov 6, 2016 21:23:24 GMT
I plug direct into the switched and then the unswitched socket for the direct comparison
No other leads or blocks
If I read you right you plugged into other things which the.plugged into the socket.
How right or wrong am I on that ?
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Post by zippy on Nov 7, 2016 9:14:21 GMT
To add to my post above, before I installed my regenerator I had all the kit plugged into a 6 way individually switched block which itself was plugged into a switched mains socket.
I added the regenerator to that, but leaving everything else the same. The result - marginally more consistency of sound but couldn't honestly say the sound was generally better.
Then I took out the switched block and connected the hifi via IEC cables into an IEC block. That meant a whole lot of fuses and switches out of the equation. The result - not a bit of difference that I could discern.
Make of that what you will, positive or negative - I remain sceptical.
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Post by Deleted on Nov 7, 2016 9:48:12 GMT
Easy solution here, a spectrum analyzer should prove most revealing in this situation.
Another interesting snippet, a long standing customer had one issue we just could not remedy despite many hours of head scratching and trying various methods
No matter what equipment we used his system demonstrated wandering imaging, from barely noticeable to quite annoying.
Went through the home system with a tooth comb, to the extent of removing all the sockets feeding the audio system and individually checking wiring orientation, separate CU / wiring etc.
He put up with this for five years, three weeks before he moved from Dorset, SSE were called to a fault in the road found that who ever layed the original wiring after the war had it out of phase.
They fixed the fault and replaced a good length of wiring in the road, after that it sounded fabulous irony is the place he moved to just wasn't the same sonically, he was say we say slightly miffed!
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Post by Sovereign on Nov 7, 2016 10:32:26 GMT
Blimey, what a story!
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Post by pinkie on Nov 7, 2016 10:51:29 GMT
I plug direct into the switched and then the unswitched socket for the direct comparison No other leads or blocks If I read you right you plugged into other things which the.plugged into the socket. How right or wrong am I on that ? I think you are correct Mike but I'm not sure of your point. I have no switched sockets - this is France. However, my equipment is connected with fuses and switches - normally We compared that with a direct unfused unswitched connection for the power amp We heard no difference Perhaps one fuse spoils the sound but having a 2nd fuse in the connections balances it back up again. Maybe that's why these mains things never work for me - I have counter-balancing fuses |
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