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-   -   Raleigh Audio Preamp - somebody heard ? (http://www.diyaudio.com/forums/tubes-valves/115329-raleigh-audio-preamp-somebody-heard.html)

dejanm 12th January 2008 09:47 AM

Raleigh Audio Preamp - somebody heard ?
 
Hi,

I am thinking of assembling a pre-amp and I found this article and schematic on the net:

http://www.raleighaudio.com/figure_18.htm

and it seems very promissing to me. Did somebody made it already or at least heard it ?

By the way, very good comments here:

http://www.raleighaudio.com/chapter_1.htm

Stixx 12th January 2008 09:51 AM

I think Bas Horneman has built a Raleigh Audio linestage...

Just do a google on Bas Horneman, he used to have his own website...

andyjevans 12th January 2008 10:04 AM

I built a version of it - used IXYS anode load, and 5676 DHTs, with a LL1540 transformer. It sounded very good indeed - very detailed and immediate sound. Very impressive - I'd recommend it thoroughly.

The parafeed cap is critical. I tried a whole lot of caps and the best by some way were the Russian teflon caps. I had to use quite a few 0.1uFs in parallel - I think I settled on 15 making up 1.5uF. Took up a lot of space, though I used the 200v versions.

This circuit is ideal for the RAKK DAC, which is what I was using, and the total output was just a fraction over line level, hence the LL1540 didn't overload, which it would do with more voltage into it.

dsavitsk 12th January 2008 06:39 PM

2 Attachment(s)
I've built two different versions of this. One is a preamp that uses cinemag input transformers, Magnequest outputs, and a quad of 12a4 tubes, and auricaps for the parafeed caps. It sounds pretty good -- actually, it sounds pretty nothing in that it seems to have almost no sonic impact at all. If anything, it might be a little flatish sounding, but bumping the current through the tubes seems to help that a bit. Biggest influence on the sound seems to be the auricap.

The other is as an output stage to a pcm1794 based dac. That one uses the Lundahl transformers on the output, a quad of triode strapped 6688's for the tubes, and Mundorf silver oil caps for parafeed.

It's a nice design, but not one you'll likely be happy with if you want a typical SET sound. I go back and forth between this dac and a ad1865n-k based nos dac as to which I prefer.

dejanm 14th January 2008 01:15 PM

Thanks guys. I have a bit better picture now ...


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