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Naim Pre amps power supply

Cheers Andy - some of your suggestions I had already decided to do - mainly the re-jigging of the layout and adding screened signal cable. The eventual plan is for this to go in "prefix position" - i.e. underneath the LP12, so this is all a temporary home for it while I play with the phono boards. Hence the wayward signal wiring.

I think the hum is being caused by the unregulated DC, as the boards have performed fine previously when fed with a regulated signal (though the new diycap confused matters). So I'll probably first rejig the layout of regs and 323s, having DC coming in from one side, and signal in and out from the other side.

Re the 0v from cartridge, I've been slightly naughty there - for expedience while fiddling, I have tied the LP12 earth strap back to the preamp 0v post (I see that Tim's doing the same) - as the hicaps that supplied both pre and phono power shared a common ground, I thought that would be OK. I did also tie the -ve on the BNC back to the 0v coming from the power supply - hard to see in the pic. One more thing to address now that the PSU isn't connected.

Looks like I have my weekend planned ;)

If all that fails, I'll pop some regulatio in the PSU box itself.
 
Thanks Richard.
I assume the Cap bit to meen capacitor, but I thought that was a single component...or does it meen transformer/regulator/capacitor assembly?

Paul.
 
Well, problem solved. It was all in the layout of the prefix end - I've not had to add any regulation to the PSU box at all.

DIYPrefix done right(ish)

As you will see, I've moved the boards around (the previous layout was me being lazy and not wanting to move the phono boards from how they were before I decided to add local regulation).

Signal in is now twisted with a 0v wire - still got some slack to it, as I want to be able to turn the boards over for more molestation.

I've also taken the signal out wires away from the DIN socket - this is now used only to supply power. It's flying free at the moment, as once I've finished fiddling I'll lose the socket and hardwire it to a power cable as per prefix - but still keep signal cables separate.

Because the 0v for the output signal no longer uses the DIN, I've connected the screen for the output cable to the 0v - if that's wrong, please shout!

So it's now hum free, and sounding good. However, since I last ran it, I have popped some blackgate caps into the main gain section (thanks for the loan, ced), which have made a big difference to the sound as well (but that's for another thread).

Thanks to all for the pointers, and sorry for hijacking your thread, Sid. Hopefully some (or all) of it's been helpful to you - I reckon this hicap clone (of sorts) has cost me around £80 - certainly under £100, using the TPR modules and Les's lovely cheap transformers etc. However, I did have the case already.
 
Excellent stuff.

It also highlights that often what is more important is not what you use, but how you use it!

The difference between good and bad design can simply be a wire or two (or on a PCB a track or two) in the wrong place. It may also give you one of the clues as to why the same circuit can perform so differently in different applications.

I'll be interested in your views on the BG's, once they're bedded in.

Andy.
 
Absolutely - thought this could be a good lesson for all ;)

Re black gates, I was lucky enough to borrow some from ced that were already run in (he marked the polarity he'd used). I popped all four into the main gain board, and (on CD) I was impressed - more detail, more bass and some taming of the top end.

However, now I have the LP12 producing hum free sounds again, I had another listen. I'm not as convinced now - I dropped the standard caps back into the gain boards, and found my toe was tapping more. I also found the top end a bit flat with the BGs. Ced also sent me two Silmics to try out, and these were more to my taste, to be sure (I put them in the feedback position on the main gain boards). So in summary, I'd say that the BGs are a bit "hifi".
 
My findings in a nutshell Richard.... I've never been able to get along with BGs although I do hear many folks do. I prefer the Panasonic NHG series, low impedance caps - the best all round cap I've heard so far. It may be that I'm listening for different things in the music I suppose so don't take this as written on stone tablets.
 
From Andrew:
The difference between good and bad design can simply be a wire or two (or on a PCB a track or two) in the wrong place
Click to expand...
When I first laid out a certain power amplifier board, the prototypes oscillated, if provoked, at the usual ten Megs - (why is it always ten Megs I wonder).? Resiting two of the tracks leaving a bit of space between them, sorted the problem completely.
 
Richard,

Can I suggest you try and live with the BG's for about a week?

They are supposed to idle in a given situation and it's an AC effect more than a CD one suposedly, so fitting them elsewhere may eliminate some of the previous burn-in.

This whole burn in is my primary reason for disliking them, BUT, courtesy of another kind Pink-fisher I tried a single pair recently in my Prefix.

I was looking for something to replace the input 10u cap, since this has to be this value and any non-linearities it introduced would be amplified a lot by the subsequent stages. It's also VERY tight for space in there.

I decided a BG was worth trying and the first impressions were of better bass (tighter, more characterful) but everything else was a bit horrible.

Over the course of a week the improvements semed to move up the audio band to the point last night they were very listenable.

There's a significant 'edge' now gone from the vinyl replay and things sound like a good film cap to my ears. There's more detail but not in an in-your-face kind of way, but a subtle, beguiling way that draws me into the music.

I've no inclination to put them everywhere (due to the burn-in ad price issues) but in areas where only a 10u will do (and films won't fit) they seem to be as good as the best film caps at present.

Time will tell more, but the addictive nature of the music at present tells me things are good.

I should try some 10u Silmics though.

Andy.
 
Richard/Andy

Are you using the BG N types?

If so is there anywhere other than Audiocon to get them from? (don't say HifiCollective since last time I looked they were even more pricey than audiocon)

Tim
 
Tim,

The pair I've tried are N's, 10u, 50V.

Audio Note no loger sell components, HiFiCollective are now the source, and for teh above value were about 50p cheaper than Audioconinternational.

Andy.
 
There is some suggestion that Rubycon and BGs are manufactured by none other than Panasonic. I'll dig a bit and find some more info but as Panasonic produces half the planet's bits and pieces, it seems logical.
 
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