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Posts by tyre

 http://www.head-fi.org/t/611348/help-needed-to-upgrade-the-capacitor-in-otl-tube-amp/15#post_8417041  http://www.muzique.com/clones.htm 
I remember starting that thread years ago (under a different user name). After my first haphazard test build, I eventually worked out the noise/hum problems by rebuilding it with a better power supply. The amplifier worked well afterwards. The output impedance of this amp is relatively high though. I had planned on doing a pcb layout but never got around to it.   Here's an archive.org link to the original...
Regarding the recent SRM-252 replacement wall-wart discussion, here's a relevant link: http://tangentsoft.net/audio/wall-ps.html  
    I wouldn't. Kevin Gilmore specifically recommended against using an unregulated supply in this post. http://www.head-fi.org/t/223263/the-stax-thread-new/22995#post_9532128 In all likelihood, the original unregulated 12V wall-wart was designed so that the output voltage would be "pulled-down" to the proper 12VDC under load. Unloaded (or underloaded) wall-warts typically output a much higher voltage. The wrong wall-wart may ruin your SRM-252. Remember that the voltage...
Here's a possible solution for the SRM-252 power supply. This isn't really a recommendation as I haven't tried this one myself, just a suggestion. It could potentially be a piece of junk. http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_162996_-1 12VDC at 500mA with a 7812 linear regulator and a 2.1mm x 5.5mm connector. A polarity reversing adapter would be needed for center negative, otherwise the cable would have to be cut and the wires...
  As far as I know, the Elpac WM series wall-wart that originally came with the Gilmore Lite is also linear regulated, but I understand what you're getting at. The audiophile in me would also immediately go for a linear supply over a switching one, if given the choice. My point was that we shouldn't dismiss switching power supplies entirely. If done right, they seem to work fine for audio purposes.
The Stax SRM-252 and Koss E/90 have switching power supplies within close proximity to the amplifier circuit. They both work just fine.  
Thanks for looking it over. Most of the part values were chosen somewhat arbitrarily. Any improvements that you think are worthwhile, feel free to add.   On a side note, this schematic of the SRM-001 by kevin gilmore might be of interest.   http://gilmore.chem.northwestern.edu/stxp.gif
  It's just a derivation of an amp from tubecad. The load resistor value could be adjusted.   http://www.tubecad.com/november99/page9.html
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