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The ultimate DIY? A Stax SRM-T2!


spritzer

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WOOT future elec and mouser orders are in. Tomorrow night I'll do an Allied and Digikey run.

To top it off the wank-factor-9000 resistors have been ordered too :D

You'll have great fun! Takes a while to stuff those monsters. Mine are finished now and all components are in. Just waiting for transformers and casework.

Defluxed both boards a couple of days ago - quite a job given the size, but worthwhile since flux is not consistent with high voltage gradients long term. Even sprung for a set of four xf3 Mullard tubes and Pearl tube coolers. Means you can't see the glow, but reduced envelope temperature extends tube life by a factor of about 2 times, allegedly.

Getting a woodie thinking about it :D

Using the waiting time to get on with finishing off a stalled Blue Hawaii. Like most stalled projects this was down to casework. But Hammond have fairly recently introduced some really sexy 19" cases. Extruded side panels, black powder coated, everything 1/8inch thick, and with perforations on top and bottom towards the rear of the case - so right over the heatsinks. Rack mounting ears are separate and so can be removed. I've ordered one and will report back on how good it looks. I'll need a second one for the PSU of course. Their part number RM2U1913VBK.

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Craig, do you have a recommendation for a good flux remover? Pure alcohol and large boards have never worked well together in my experience no matter how much compressed air you use.

I use iso-propyl alcohol (or propan-2-ol in modern parlance), which I buy in litre bottles from Farnell. For the big board I used a large baking tray with half and inch of IPA in the bottom, dipping one edge of the board into the tray. Then repeated use of a small stiff brush dipped into the tray every couple of seconds, finishing off with an aerosol alcohol spray. Dry board with paper towels to blot off the excess (it will come off brown to start with). Repeat a couple of times until the board is clean and free from flux streaks.

Never used compressed air.

Bit of a fiddle, but you get excellent results with a bit of patience.

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Hokay - I said I'd report back about the new Hammond cases. Pretty impressive - particularly for a production case. Fits my roll-your-own BH boards a treat (and that was a relief!).

I've shoved some images here:

http://www.tech-enterprise.com/tekstuff/P7260502.JPG

http://www.tech-enterprise.com/tekstuff/P7260503.JPG

http://www.tech-enterprise.com/tekstuff/P7260504.JPG

http://www.tech-enterprise.com/tekstuff/P7260505.JPG

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Good news, the batch of 4 just came back from polishing, and its better than before and

just great. Should be at the anodizer by noon, then maybe another 10 days.

That good sir will be great timing!

That hammond case is going to be great for the KGSSHV...

As long as its 13 x 16 on the inside

Limiting internal dimensions are 12-3/4 x 16-3/8

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Hokay - I said I'd report back about the new Hammond cases. Pretty impressive - particularly for a production case. Fits my roll-your-own BH boards a treat (and that was a relief!).

I've shoved some images here:

http://www.tech-enterprise.com/tekstuff/P7260502.JPG

http://www.tech-enterprise.com/tekstuff/P7260503.JPG

http://www.tech-enterprise.com/tekstuff/P7260504.JPG

http://www.tech-enterprise.com/tekstuff/P7260505.JPG

did you move the -400V trace that runs way too close to a couple of the standoffs?

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did you move the -400V trace that runs way too close to a couple of the standoffs?

I actually missed that - so the trace still kisses the hole (as it were...). So I have gone for nylon standoffs with a plain hole. Although I have those fixed at the moment with an insulating washer under the head of steel self-tapping screws, I will probably move to nylon screws and tap the holes.

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If they are the original board files then they are likely the same ones I just bought off Kevin.

I'll have to remember to get some nylon standoffs.

If they have that proximity problem, you need to insulate the screw heads too or use insulating screws. Because the screw head shorts to the groundplane, and the thread is still right next to the -400V trace.

I built my boards around 4 years ago, before I got heavily involved in head-case - so I used the pdf files on Kevin's site and made my own. Bit of a PITA because the holes aren't plated through of course, so lots of fiddly assembly work. Protected the whole shebang after building with baked-on conformal coating in lieu of solder resist protection. So it should survive being sprayed with salt water......

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Are there different versions of the SRM-t2?

Japanese manual says it has 50 kilo-ohms (single ended) or 100 kΩ (balanced) input impedance:

That Japanese manual seems to have very odd wiring for the XLR's. Pin 3 connects to RCA centre pin, and pin 1 connects to RCA outer on the output. The switched RCA inputs effectively short pins 1 and 2 to RCA outer and pin 3 to centre. That is counter to conventional XLR wiring where 1 is shield, 2 is hot and 3 is return.

Kevin pointed me at some Neutrix XLR-RCA adaptors, which indeed do the conventional thing of shorting pins 1 and 3 to RCA outer and feeding 2 to RCA centre.

Unless I am missing something?

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anodized parts will be delivered to me wednesday morning, so i will start shipping this batch wednesday/thursday

(subject to size limits of vehicle, which should probably only be 3 of the four at once)

Who wants the next batch which could be either 4 or 6 chassis.

Voltron/Icarium, you can do one each for now... Makes things a bit easier.

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anodized parts will be delivered to me wednesday morning, so i will start shipping this batch wednesday/thursday

(subject to size limits of vehicle, which should probably only be 3 of the four at once)

Who wants the next batch which could be either 4 or 6 chassis.

Voltron/Icarium, you can do one each for now... Makes things a bit easier.

Whatever is easiest. I can take one or both for mine. Thanks for all the hard work and hauling.

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Delivered by courier.

I did get all 16 of the fronts/backs, so i have to trace down what the hell happened.

Don't care about the tops and bottoms, i can make more.

The heatsinks are a bigger problem.

It is likely that they are sitting in another crate that got misplaced.

Phonecalls in 1.5 hours.

Just can't get good help these days. No one gives a shit.

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