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Post by yomanze on May 2, 2017 12:05:10 GMT
Post edited am sure my comments about price are just flaming... hey, if it works for you. Is this the same design as Nick Gorham's board?
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Post by MartinT on May 2, 2017 12:37:21 GMT
The MCRU Ultimate DC Blocker is Nick's design. Whether it's the same as Nick's board I don't know because we don't have the circuit details and I'm not going to open up his design and spill the beans. If David wants to enlighten us, I'm sure he will.
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Post by yomanze on May 2, 2017 12:46:34 GMT
The MCRU Ultimate DC Blocker is Nick's design. Whether it's the same as Nick's board I don't know because we don't have the circuit details and I'm not going to open up his design and spill the beans. If David wants to enlighten us, I'm sure he will. Did you have hum issues with your P10? Am struggling to understand why a unit that blocks DC on its output (PS Audio mains regenerators) would benefit. |
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Post by MartinT on May 2, 2017 13:32:55 GMT
No, I had no hum issues with the P10. The DC blocker is, as has been said before, improving the performance of the P10 itself (which has a dirty great toroid inside) and therefore the quality of the regeneration. It's the only possible explanation to the sound quality improvements I'm hearing.
David Brook (who sells the P10) has confirmed that other customers have heard similar improvements. This is not just about reducing hum from transformers.
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Post by MartinT on May 3, 2017 7:33:45 GMT
Further listening last night convinced me that the DC Blocker is not going back. The SQ improvement is really superb. I've bought it.
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Post by pinkie on May 3, 2017 8:40:37 GMT
Did you measure the DC offset on your mains Martin? What DC offset do you have ? Does it vary during the day?
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Post by MartinT on May 3, 2017 9:18:40 GMT
Still haven't got round to it, Richard. I'll hopefully get the meter out tonight.
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Post by pinkie on May 4, 2017 7:24:40 GMT
The earth-neutral impedance will vary depending on which system is in use: Nowhere should the resistance be as much as 40 Ohms, let alone 200. Apologies for the discontinuity. It's no longer possible for me to pop to the Bull at Farningham and buy Graham a pint. I'm grateful to him for eventually supplying me these photos Extracts from the following 2 publications BS7671 2008 (current edition "The Regs") and the IET onsite guide (current edition)  Relevant extract from on site guide  And from "The Regs" themselves  So 40 ohms is fine. And 200 ohms is the correct recommended maximum for a TT system. The Table in the image above may not be that easy to read, but it shows the maximum impedance for each value of RCD - and the bottom one is 500ma (which we have in France) - hence the 100 ohm maximum impedance in France |
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Post by MartinT on May 4, 2017 20:30:56 GMT
I couldn't get a decent resolution on my two DVMs to properly measure the DC offset on my mains. All I can say is that there is something between 0 and 1V DC offset on my mains, which varies. Since it takes only a few hundred millivolts to cause some transformers to go temporarily into saturation, that's reason enough to block it. Interesting, but my ears convinced me some while ago.
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Post by MikeMusic on May 5, 2017 8:42:35 GMT
There's a lot to mains coming to light here.
Surprised me when Tony measured fluctuating DC at my place.
AC giving a taste of DC.....
Reminds me when we had a gas problem.
Cause : Water in the gas, due to incredibly cold temperatures.
Had never heard of water in gas before, condensation I believe.
I bet there are other things we don't know about influencing mains and stopping systems delivering their full potential
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Post by pinkie on May 5, 2017 9:21:08 GMT
I couldn't get a decent resolution on my two DVMs to properly measure the DC offset on my mains. All I can say is that there is something between 0 and 1V DC offset on my mains, which varies. Since it takes only a few hundred millivolts to cause some transformers to go temporarily into saturation, that's reason enough to block it. Interesting, but my ears convinced me some while ago. No. You can't measure DC on mains accurately with an ordinary DMM unless you build a simple filter circuit. It's simpler to use a more sophisticated meter like a fluke 287 with the facility to measure DC and AC simultaneously. There will have been a few measurements quoted which are questionable. Barry's was almost certainly correct It's a wonder anything works at all with all these things to discover about mains. Fortunately - in this house at least - it seems to be just fine. |
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Post by MartinT on May 5, 2017 9:48:33 GMT
I'll get my 'scope on it sometime, I may just have the resolution to see the offset and scale it between AC and DC views.
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Post by Deleted on May 8, 2017 20:33:05 GMT
Having built many of these wit filter I decided to do some SIM work to find the right value caps.  |
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Post by Deleted on May 8, 2017 20:38:10 GMT
Many years ago I did some work on Faradays Non Watts components circuit I will dig it out, it will be interesting to see the result using a 50Hz resonant transformer circuit.
I made few in the pass about 50KVA+ versions but as you will have seen they do have a squared up output, but the voltage stays constant, now add that to a Hi Q 50Hz Filter could we improve things further ?
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Post by MartinT on May 9, 2017 5:12:33 GMT
The voltage drop and power wastage even at 5A is tiny, and my system idles at less than 1A, peaks at about 2A (average). Looks like 1F is an over-the-top value and not required.
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Post by Deleted on May 9, 2017 5:16:41 GMT
The voltage drop and power wastage even at 5A is tiny, and my system idles at less than 1A, peaks at about 2A (average). Looks like 1F is an over-the-top value and not required. Yes that is a symbolic circuit caps under test are list to the left of the charts. |
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Post by MartinT on May 9, 2017 5:20:46 GMT
I was looking at the bottom listed one with the not-so-good ESR. Now that I look at it closely, is that 10F?
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Post by Deleted on May 9, 2017 5:43:14 GMT
I was looking at the bottom listed one with the not-so-good ESR. Now that I look at it closely, is that 10F? Yep close +20 or -15% super cap. P.S. they also sound crap due to a strange chemical reaction which only kicks in at 0.3V-0.5V before they charge. Adding distortion to the nice Sin Wave, so do not use. |
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Post by MartinT on May 9, 2017 6:12:36 GMT
I use a smaller supercap as DC decoupling in my Caiman SEG DAC, on Stan's advice. I think in this application, with a constant 5V across it, it sounds fine.
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Post by brettj on Oct 31, 2020 20:27:28 GMT
There is a MCRU ULTIMATE DC BLOCKER for sale.
Do you still have yours Martin?
Considering plugging it into my Perreaux integrated amp, which has a hum.
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