Post pics of your builds.... - Page 600

This is my recent build ...

That's absolutely gorgeous, inside and out. One question, how did you go about building that enclosure? Was it modified from something off the shelf? and the screen printing on the front, custom work, or did you do it yourself too?

I hope he enjoys his gift, I know I sure as hell would, that looks like something off the shelf, in the best way possible :D I think people often underestimate how much good clean wiring can do for aesthetics, its nice to see something built that tidy!

Peace,

Chris

I haven't posted any new builds on HF in a long while but I'll follow Nate's lead as this build was influenced by him. 

This project started after I had rehoused a RAKK DAC originally built by Nate.  That left me with the old Hammond steel chassis so I naturally had to use it for something.  I figured it was time to do a cheap EL34 based Stax amp  for the masses which would still outperform what's commercially available.  The key requirement was to build it on the cheap so I took cues from the WES and used the same power supply setup (+300/+600V) but this one had to be able to accept RCA input without any additional stages and DC coupled would be a plus.  That said focusing on making fully DC coupled tube amps often leads to something that sounds terrible so I wasn't too hung up on that. 

The amp circuit is pretty simple, it uses the same cross coupled input stage of the Stax SRX.  That stage is fully DC coupled internally but AC coupled to the next stage and I built it with 6SL7's as I had them in stock.  They are also the only good choice for electrostatic amps in an octal envelope as we all the gain we can get plug high bandwidth.  The output stage is similar to the WES so grounded cathode with triode strapped EL34's but I used anode resistors instead of chokes to load the tubes.  The chokes when done properly (i.e. not how they are done in the WES) would be superior but they also cost more to have custom made so nice Mills non-inductive wire wounds it was.  In this setup the amp has two capacitors in the signal path, small cap between the front end and the output stage and much larger output caps.  Due to the single power supply output caps could not be avoided so this is not a bad result. 

The tube heaters for the front end tubes are fed from the small DC supply in the corner with tubes wired as two pairs in series to lower the current requirement.  The output tubes are fed off two transformer windings which is crucial in an amp such as this.  The heaters have DC on them so they must be left floating.  It's also a good idea to isolate the channels from one another.  The high voltage power supply is a very simple design I did with Kevin Gilmore last year and it's basically two 300V supplies stacked one on top of the other.  The bias for the headphones is taken off the +600V line and fed through a voltage divider to get the desired voltages. 

I quite like the end result and it more than holds its own against the Blue Hawaii I built earlier this year and it was cheap.  Not sure how much since I had everything in stock to build it but it was probably less than 1k$ even with all these very nice parts. 

Stunning.  I want one even though I have no Stax.  

Indeed, with that multi-hundred volt supply

+600V is nothing, we have one on the drawing board that is +/-800V and we can go even higher...

Here's my almost completed MSSH. I had it running in a shoebox, but when I boxed it up properly the right hand channel isn't working, so a bit of troubleshooting needed. This explains why the top isn't fastened down and it's still on a workbench in my shed.

Anyway it's in a 150 x100mm mahogany case. The top and bottom are 5mm thick plate aluminium and I think that the knob is 45mm alu. The wood is treated with boiled linseed oil. I'm pleased enough with it.

Sorry about the poor photo, I took it with my phone.

Indeed, my corona-phone prototype runs on ±3kV supplies

what happened with your super DIY build? i think that was yours right...?

The tube heaters for the front end tubes are fed from the small DC supply in the corner with tubes wired as two pairs in series to lower the current requirement.  The output tubes are fed off two transformer windings which is crucial in an amp such as this.  The heaters have DC on them so they must be left floating.  It's also a good idea to isolate the channels from one another.  The high voltage power supply is a very simple design I did with Kevin Gilmore last year and it's basically two 300V supplies stacked one on top of the other.  The bias for the headphones is taken off the +600V line and fed through a voltage divider to get the desired voltages. 

I quite like the end result and it more than holds its own against the Blue Hawaii I built earlier this year and it was cheap.  Not sure how much since I had everything in stock to build it but it was probably less than 1k$ even with all these very nice parts.