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The ultimate DIY? A Stax SRM-T2!


spritzer

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kerry came up with this one... a BHSE with the servo's from a T2.

http://gilmore.chem.northwestern.edu/BlueHawaii-T2-Servo-v1-2.zip

opens with ltspice.

I forgot to knock down the voltage going into the opamp servo, but it is the same as on the T2. Model still works, though I'm not sure what would happen in the real world. I just added it to my model. I would love to get feed back on this. It's actually the T2 output and the BH input with servo similar to the vendetta / T2 for the input section.

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A beautiful set up there Craig! The knob looks great. What are the tube dampers you are using on the el34?

They are Pearl tube coolers. Main aim is to even out and reduce envelope temperature - increases tube life by a factor of two - but they do have a damping effect too. Corrugated and blackened copper held on with high temperature O-rings. Important with four rather expensive Mullard xf4 original EL34's. Got them from Parts Connexion.

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As for masking parts to be powder coated...you can use about any product, as the coating really is powder. I used Blue painters tape, so it wouldn't leave a glue residue. Then my powder coater removed the tape after coating/before the oven. Make sure your powder coater masks threads, as all don't. If not I found the best thing is to re-chase with a tap. You can get smooth or hammered surface textures, as well as gloss or satin, but I'm not aware of a flat powder coating yet. The baking process would make it difficult to produce flat I'd imagine. Smooth surfaces generally are about 2 mil, with textured about twice that. At least in my experience. Clear coating screw heads is an excellent idea.

I used to have a lot of pipe powder coated, for deck railings in Alaska. And when building custom computer cases.

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@Craig - Beautiful black box(es) you have there. Love the pics.

Is that wood knob a custom micro-machined KG original?

It sure is. I sent KG a chunk of Lignum Vitae, and he did the business. There are some detailed pics he took before shipping it way back in this thread somewhere. A real source of joy - just waxed it to bring out the grain.

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As for masking parts to be powder coated...you can use about any product, as the coating really is powder

The neat thing that I've done in the past in products I've developed (mainly mil stuff) is to have the panel engraved after either powder coating or anodising. The engraving can either be left as it is, or filled with colour - or a range of different colours. Much more robust than silk screening.

One of the old timers from Tektronix was telling me the way they developed the lettering for the old tubed 500 series was to have a load of panels done in different ways (engraved and filled, screen printed etc) and stuck them to the floor in Tektronix's entrance hall. Employees were required to walk on them when they passed to pick the most robust. The original choice was engraved and colour filled. They then moved to silk screening once they had a process that also passed the walking test.

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I forgot to knock down the voltage going into the opamp servo, but it is the same as on the T2. Model still works, though I'm not sure what would happen in the real world. I just added it to my model. I would love to get feed back on this. It's actually the T2 output and the BH input with servo similar to the vendetta / T2 for the input section.

It

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Pics here:

And that looks truly spectacular. Looks like the the amp equivalent of a custom car job. MMMM.

Inu's powder coated T2 looks great - and his coater managed to get right in to the heatsink fins.

I did my KG triode chassis with black crackle finish - which you can get from specialist suppliers of car restoration accessories. Sprays on and looks just like flat black, but as it dries (in the domestic oven - shhh, don't tell - the wife was out...) it crackles.

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Here's some fun stuff. It's my draft for the BHT2E (per Inu :D) power supply. It's got +425V, +15V, -15V, -295V (via 160V against the -455V rail), -425V, and -455V (via 30V against the -425V rail). The dimensions are 12" x 5.5".

abpowersupplyv10.gif

Once, I have this built, I may take a BH board and hack it up a bit to test the design. Any thoughts are greatly appreciated.

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