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The Headcase Stax thread


thrice

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I took a break from listening to Leona Lewis, Beyonce and Kelly Clarkson to daydream about someone to build me a DIY electrostatic amp for intermediate DIYers. I came up with a quick shortlist and thought of some accompanying comments.

runeight

dBel84

pabbi1

n_maher/Vince Vaughn (does he really know anything? or is all just acting?)

amb

spritzer (Plus: hands of a Norse god Minus: risk of amp going viking)

Justin? (maybe this project too difficult for him, apparently not having built a tube amp, just hybrids and SS?)

Jude (c'mon, you don't want an amp built by him?)

Mikhail (just shoot me now, please)

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spritzer (Plus: hands of a Norse god Minus: risk of amp going viking)

I believe the term is to go berserk... :nate:

Justin? (maybe this project too difficult for him, apparently not having built a tube amp, just hybrids and SS?)

I do seem to remember a certain Aristaeus being a tube only amp. :palm: There are diodes in the PSU and regulators but all the amplification is done by valves.

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Since we are on the subject, the mini ES-1 aka. The A11 is up and running. :) It's not yet running at full power (+/-260v instead of the +/-350v it should be running on) but that's just because I'm lazy and already had a the PSU ready to go. Somehow I always forget about my old KGSS supply which is ideal for this stuff... :palm:

img2105c.th.jpg

I'm getting some channel imbalance so I'll have to check all those connections and swap out the tubes but I'm letting the caps discharge for now. DC offset was pretty high at roughly 20-35v per phase so I need to put in some adjustment for that.

As for the sound, I spent some 40 minutes listening to it and even crippled by crappy parts, a low voltage PSU and using the Lambda Pro's, it's better then the Egmont. :)

img2112n.th.jpg

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C'mon, you can't call it a mini ES-1 without EL34 tubes and a couple of wall warts.

I do seem to remember a certain Aristaeus being a tube only amp. :palm: There are diodes in the PSU and regulators but all the amplification is done by valves.

Ouch! I thought I was deviously poking fun at Justin, but I'm a total idiot! :asshat: I totally forgot about the Aristaeus, and I was just listening to it last night.

Plus, he's retired.

I have hope there might be a coming out of retirement party!

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Wow, that is flattering, but if I can fuck up a WORKING BH, well, yeah. I'd vote Naamanf to build mine, pending his schedule, and maybe he'll get around to a new stat build, like...

... a VULCAN?

vfin3.jpg

vfin5.jpg

The perforated aluminum tops were just painted with hammered copper paint, so pics this pm. Oh, and Steve about that teflon jack (my last long awaited part to go fully arcy-sparky).

Specs: parallelled 6s4a, pseudo BH ccs, 5 position adjustable bias (courtesy of Naamanf), and seperate 350v-450v adjustable (or fixed) psu.

The creator is luvdunhill, and if either of us could case something worth a damn (though, he still has a chance). I have a curved aluminum case, but can't seem to get it welded together properly, where screws and JB Weld have all been epic fail. Weld, gaps filled, ground smooth, then powdercoated. Should just take another couple of months, so the wood case is a temp hack.

alcase1.jpg

alcase2.jpg

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A bit, but not really... it is two of those units, one slightly smaller, where they stack. It looks really wild, and the .20 aluminum helps act as two huge heatsinks. Actually, the design came from someone who is completely unaware of the whole headphone world, so quite the coincidence.

Now, to fuinish it up... THEN, make a curved case in wood... guess who will be involved in that... well, or so I hope...

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I like that trapezoid-type metal case, it should look pretty good on a rack.

I finally got a tube tester. After some research, it seemed as if the B&K solid state tester is reliable and easy enough for a non-DIY person like me to use. Calibration is supposed to be relatively simple with this model, but I think it will be beyond a total electrical ignoramus like me. So far its readings are fairly consistent with the reported readings by the tube sellers. The main thing I want to do is weed out bad tubes and do some simple matching of singles and pairs or confirm supposedly matched quads.

I'll need to get some socket savers, or else the Position 14 octal socket is going to wear out real quick. :)

Tubetester.jpg

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I finally got a tube tester.

Good call on the B&K, especially the 747. I'd start scouring the countryside for someone to calibrate it for you though. After looking into calibrating my own tester I started to realize that while simple enough at first glance, in order to do it and have it actually make a difference you really do need some specialized equipment. Too bad you're halfway around the globe, the guy I ended up tracking down is pretty reasonable if you can convince him to work on your gear.

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I think I can find knowledgeable people to do the calibration, but probably no one who's actually familiar with this tester. If no one local can do the job, I'll just suck it up and either ship it to the US or ask someone traveling there to bring it over and then ship it to an expert.

My hands hurt! Nobody ever mentions that you have to push the buttons and keep them held down. The fingers on my left hand hurt! Two buttons have to be pushed, then Test button has to be held down for a few seconds, and then the Life Test switch has to be pushed to the right and held for a few seconds. The controls are stiff and it hurts!

And the socket is really tight, I had one tube seemingly super-glued in there and it took me three minutes of grunting and pulling to get it out. Now I know why the labels on the tubes come off.

And not only that, the tube heats up. Not really hot, but hot enough that it hurts. So my right hand hurts too, from pulling up the tubes and the heat.

And all I wanted to do was listen to music! :palm:

Edited by Elephas
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I have an SRM-T1W with selectable voltage. I don't think a 100V unit would be difficult to convert to 115V. There are instructions and photos somewhere.

$3400 for the package seems like a decent price, say $2500 for the SR-Omega and $900 for the amp. Assuming the headphone is in good working condition, of course. The risk of buying a used SR-Omega is probably higher than normal.

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The T1W should be very easy to change, remove the bottom panel and the familiar Stax voltage selector plug/socket affair should be in the corner, next to the IEC input.

I wonder what is the S/N since I read that Stax made some changes to the membrane in the later ones (also, there are ones with aluminium fixation discs instead of plastic ones but that doesn't affect the sound).

They did indeed change the cartwheels from plastic to aluminum but AFAIK that never made it into a production headphone. The SR-Omega I lost out on last October (with the T2) was S/N:500 (one of the last ones made) and it was fitted with plastic cartwheels. I'm not sure why they did that mod though as the stock stators are very strong and adding a stiffer brace shouldn't make a huge difference. Who knows why they did it and after the SR-007 was released they stopped making replacement drivers.

Another change Stax did was to fit those small rubber pads between the two external grills. Out baby elephant has one of the earliest sets and it lacks those pads.

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