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Moving on from the Dacmagic, who's done what?

Re over-spec'd transformers; a lot depends on the noise you get on your mains. DC in particular will saturate the core of a minimal spec TX whereas a TX with an over spec'd core will be physically and electronially quiet. What works on one house's mains can be very different elsewhere so it's difficult to draw consistent conclusions. Time of day makes a big difference to mains noise too.

A good TX is just the very first step in building a good power supply.
 
That may/should take care of DC but there's plenty of other crud on the mains to upset TXs and requireing excellent filtering after the TX.

DC blockers in front of TXs don't always work perfectly.....results are quite variable, usually quite a large cap plus diodes are needed, the cap I expect should be too big for a wallwart.
 
Clive if you have particularly bad mains that requires some forms of treatment then perhaps you should speak to your supplier.

People were stating that replacing the wall wart with a bigger transformer improves the sound. I said that was unlikely to be the case, because A. The wall wart has filtration in it, certainly suffice to support its 200mA draw. B. Because those who showed their added traffos didn't actually have any filtration in the box, so was only likely to be a retrograde step. C. Given that the wall wart is 2.5x over specced for current delivery vs what the DM actually draws why would increasing this headroom further make any difference?

Had the DM or the 64p measured any better when fed with larger transfromers I would have used them, but they sounded no better, no measured any different when running through a 200VA Holden and Fisher torroidal feeding the AC inputs.

What did make a difference, in the case of the 640p, was removing the AC power supply parts and feeding the traffos into Q-Speed diode built Hacker Cap CRCRCR rectification boards and then onto Super teddyregs directly into the DC lines on the PCB. Which is what I advised.

If you have anything other than anecdotes to back up your suppositions, on gear I'm assuming you neither own nor have measured and modded, I'd love to hear about it.
 
Simon,

I have not played with a DM but I have played with a lot of power supplies, indeed I've been working on one for a record deck over the last few days, I'd love to share details but not on a public forum.

As for DC blockers (you mentioned the DM has one, filtation or DC blocking? I'm not clear which you mean now). The ones I've built and tried myself have highly rated capacitors and diodes for safety (voltage) and performance (low ESR) reasons. I can't imagine a decent DC blocker being able fit inside a wallwart but maybe the DM has some real magic or it's some other type of filtration.

It's important when you look at mains that if you want to generalise about it you check performance not only at different times of the day but also with varied installations. As for talking to my supplier about my mains, well.....it's not that unusual to have all sorts of crap on the mains, and trying to get the data the suppliers super-impose onto our mains removed just isn't going to happen. As we move to Smart Grids and Smart Metering it's only going to get worse.

As you say there are many parts to a power supply, getting them all well spec'd so there is no weak link is worth doing. Diodes, filter cap, regs we agree on I believe. The point I'm making is that generally, if there is no other weak link in the power supply, then you will often benefit from a PTX spec's for tolerance to saturation, it many still only operate at 200mA but it can then better perform with some of the crud the mains pumps into it.

I don't know what the DM wallwart has inside it but these are general principles that can be applied to most hifi equipment. And yes I have played with this stuff, just not with a DM.
 
sq225917 said:
The Dm wall wart has a small dc blocker built in.
Click to expand...

Do you have a pic of the UK DM wall wart innards? Are input 120VAC 60Hz 24w/output 12VAC 1500mA is just the transformer. This is pics of the replacement Cambridge sent me.

http://img716.imageshack.us/img716/3204/1006247.jpg

http://img535.imageshack.us/img535/667/19746113255229404818345.jpg

Before my mod BUZZED like crazy. Zero noise NOW being emitted. Also the use of shielded and twisted cable on the 12 VAC output to the input of the DC has less interrelation with my other cables.

http://img148.imageshack.us/img148/5857/23423113305578663518345.jpg

http://www.facebook.com/photo.php?pid=268813&l=ed74d1319d&id=1834511717
 
Very different to the UK parts Jack, i don't have pics to hand, but there was a handful of components after the TX.
 
Robert said:
Playing devil's advocate, perhaps the 'improved' AC transformer is doing things that cannot be measured but are audible so some listeners?
That is a position you seemed to have adopted only recently.

By the same token, if you are going to add super regulators then perhaps some measurements on the output of the device being powered would be in order to confirm/dispel any perceived difference.
Click to expand...

Not sure I understand you regarding my position Rob. If you mean have I responded that the Maplins 3amp unit might be worthwhile on the 640p, then you need to read my previous responses more carefully. I said it couldn't hurt, not that I ever heard an improvement from it.
 
I auditioned the Rega DAC yesterday, alongside rDAC and nDAC.

Found it quite revealing, but did not like it as much as the rDAC.

USB in is limited to 44.1, surprisingly. I thought that async USB was the way forward?

Previously, I did not like the nDAC, but on this occasion, with this system and using co-ax in, it was my favourite.
 
I have tried the Maplins replacement psu and found no difference. I even let it burn in as they say. I replaced it with the wallwart that was sent by Cambridge no difference between the 3 of them. I have now reverted back to the Cambridge one as I found the plug which goes in the back of the Dac wasn't a great fit on the Maplins one.
I originally thought I could hear a slight difference but it was all in the mind.
 
Interesting the differences in my system with DM power supplies was noticeable, to the point I tried the RA. My preference was the Maplins L54, it was repeatable and my observations were shared by others.

Perhaps some systems are more revealing, susceptable ?

I was using the DM into a 32.5/Supercap/4X135/Sonus Faber Extrema with dedicated mains and seperate spurs to each piece of kit.
 
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