The ultimate DIY? A Stax SRM-T2!

[Milosz]

Thanks.... I've got a copy of Autocad around here someplace.... maybe I'll make a file- should be able to do so from your numbers; hmmm, even Visio ought to be able to handle something as simple as this, and export a .dwg or .dxf, hmmm

Hmmm.

Of course I can always just position my (unstuffed) PCB on the sheet of copper I'm using for a top plate, and using the tube socket center holes in the PCB I could drill pilot holes through the copper plate; then use these for punching. I have to use Greenlee punches, as I have no CNC mill. I guess I could use a step drill for the smaller holes.

I have all the sundry parts, and now my chassis design is coming together.....

I am guessing that I will be at a point to apply power in January~February.

That timing is fortuitous - it will be quite cold here in Chicago at that time; so it shouldn't be a total loss, any fire that may start when I first power things up will not go to waste.....at least I will be warm.

Edited November 1, 2011 by Milosz

[livewire]

Steampunk T2?

[spritzer]

My amp is working again... well kinda since one transistor is sparking nicely to the metal screw. I'll see if a nylon unit will work until I can get some PEEK's.

[Torpedo]

Both channels? Congratulations!!!!

[spritzer]

Well one channel works but the other one has a battery that's misbehaving. It's stuck at 777V and the bloody part continues to spark even after some quick fixes so it's back on the shelf while I wait for the PEEK screws.

[Torpedo]

You have a great deal of patience, my friend. I wish you can fix it and enjoy that nice beast.

[spritzer]

Slow and steady wins the race...

[pedefede]

Lifted all resistors (shinkoh) in the batteries on left channel 2+ mm. HUGE difference - noise is almost gone, and voltage is now stable. So no replacement seems to be needed.

There is still some small scratching noises, and very small white noise. I'll poke around with a scope - and probably do INU-fix on pots.

Right channel was born dead quiet, without any mods.

[wink]

Might be an idea to lift the resistors in the right channel as insurance....

[Milosz]

Steampunk T2?

Well not exactly.... here's a rendering of my design - in this drawing the copper is just a flat tan color, try to visualize it polished up shiny.....

...something like this Hagerman Cornet phono stage I put together.

[livewire]

Nice! (on both counts)

Cant wait to see the finished goods.

[Milosz]

Nice! (on both counts)

Cant wait to see the finished goods.

Thanks. The Hagerman has a more old-school look, more of a DIY looking casework. The T2 will look sleeker, I hope. The wood is bubinga, which has some pinkinsh color to it that nicely compliments the copper. I found out you have to use a special lacquer - Incralac - on copper to keep it shiny. Regular lacquer lets in too much oxygen.

The heatsinks are from Par-Metal, they have some pretty decent prices. We'll see how it goes.....

[cobra_kai]

I have a couple questions about the par-metal heatsinks Milosz - first what format do they want drawings for drill/tap holes and second are you using multiple smaller sinks or do they custom make larger ones?

[Milosz]

I am using [2 pieces] times four of their HSG-07XX heatsink, which are each 7 inches long, for a total of 14 inches. Two pieces on each side of the amplifier and two pieces on each side of the power supply. This is not as long as the entire PCB, but it does "cover" all the transistors.

I am having them cut to 3.5 inches height. I am going to be using a piece of 90 degree "L" aluminum as heat spreader; the transistors will be mounted to the aluminum on the horizontal face and the vertical face will mount to the heatsinks, similar to K. Gilmore's original. (I only hope my aluminum "L" heat spreader is thick enough to transfer the heat efficiently.)

I am drilling and tapping them myself, I haven't used their service for drilling and tapping so I don't know what file format they want. Just a guess, I bet they can probably take AutoCad .DXF or .DWG files, most everyone working with machining has some software that can read these.

[cobra_kai]

^^ thanks

[Pars]

Good thing to see some vendor info in this thread. I am looking for some IRF230s for my brother's amp, and here is what UTsource sent as far as a device picture:

The markings on this don't look like any IRF I've seen... do these ring a bell with anyone else? I guess I'll have to go with Newark.

[ujamerstand]

I wouldn't trust the pictures from utsource. You might get something that doesn't look like the ones on the website at all. If it is available at Newark, I'd go with Newark.

[Kerry]

I'm just putting the finishing touches on the T2 so here are some shots...

Here's the coupler I made to join the 1/4" shaft for the volume to the 8mm shaft on the RK50.

Here's a couple of shots of the amp

I've got some JJ's in it now, but I'm going to try the mullards next.

[Voltron]

Awesomeness!!!

[n3rdling]

Cool stuff! What length are you guys making your umbilicals?

[Milosz]

Wow. Fantastic, nothing short of fantastic.

Did it work first time you fired it up? Any tips or pitfalls to avoid for those of us who are just about to embark on construction followed by testing...?

[Kerry]

Thanks.

I made the umbilicals 30" each so the amp can sit side by side or on top of the power supply.

The amp powered on fine, but because I was using the PRP resisitors in the active batteries I had a noise issue. My suggestion is to use the Xicon resistors for the active batteries.

Beyond that just really tripple check your work. There's a lot of parts in here and they all need to go in correctly.

[The Monkey]

Great stuff, Kerry!

[kevin gilmore]

The coupler is a stock part at mouser, all you have to do is drill out one end.

[Milosz]

There's a lot of parts in here and they all need to go in correctly.

Yeah that's step I have the most problems with... I hate when that happens!

Hahahaha....