The ultimate DIY? A Stax SRM-T2!

[Craig Sawyers]

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

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

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.

[luvdunhill]

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.

[Craig Sawyers]

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.

[Craig Sawyers]

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

[kevin gilmore]

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

As long as its 13 x 16 on the inside

[nattonrice]

Yay! Almost money time... for this and the o2's to plug into it hehe.

Got everything I need for my tax return about 3 hours ago too.

The timing is impeccable

[Craig Sawyers]

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

[jgazal]

Are there different versions of the SRM-t2?

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

[url=http://earsp.web.fc2.com/log/manu/srmt2/t27_jpg_view.htm]STAX

[kevin gilmore]

Its just the pot. I don't even remember the impedance of the rk50 i put in.

Actual input impedance of the amp not including the pot is 330k.

[justin]

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?

[Craig Sawyers]

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.

[nattonrice]

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.

[Craig Sawyers]

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......

[nattonrice]

Cool I'll make sure to grab some nylon standoffs and screws, thanks =)

[spritzer]

I've used nylon standoffs with either nylon screws or nuts and no issues what so ever.

Are there different versions of the SRM-t2?

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

[url=http://earsp.web.fc2.com/log/manu/srmt2/t27_jpg_view.htm]STAX

[Craig Sawyers]

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?

[spritzer]

Most of the non-US manufacturers wire the XLR's like that according to some standard which I'm forgetting at the moment.

[kevin gilmore]

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.

[Voltron]

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.

[kevin gilmore]

The 4 chassis are all back from anodizing...

So 2 will ship today, and 2 will ship tomorrow.

Justin wants to do another heatsink run. Which would mean that more T2's would be available.

(yep lets prolong the pain and agony)

So how many people would be interested in a second run of T2's ?

[kevin gilmore]

Just great... One of the chassis is missing...

[Craig Sawyers]

Just great... One of the chassis is missing...

They didn't ship by UPS by any chance?

[Driftwood]

Justin wants to do another heatsink run. Which would mean that more T2's would be available.

(yep lets prolong the pain and agony)

So how many people would be interested in a second run of T2's ?

I'd be interested.

[kevin gilmore]

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.

[Craig Sawyers]

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

It's what I call the "good 'nuff" society, or JTL (Just Too Late) rather than JIT (Just In Time). Fingers crossed that these turn up.