The ultimate DIY? A Stax SRM-T2!

[nopants]

congratulations on your build. i separate my psu and amp sections but it looks so much more menacing as a stack

[Craig Sawyers]

I have mine on two separate shelves - in a stack it gets pretty toasty!

[hfhimeka]

Agreed.. probably a better idea for helping with heat dissipation and keeping the units.. "cooler".  I guess it's time to buy a shelf / rack!

[Craig Sawyers]

Cooler is a relative term with the T2 Clone 

[johnwmclean]

Great achievement, well done!

[gepardcv]

Looks like you're running it from the audio jack of your laptop? Congratulations on your build and extra points for ignoring the DAC insanity!

[nopants]

The 216s in one T2 channel went bad, unfortunately when the headphones were connected...no smoke or anything, just a short between gate and source when I was diode testing. Haven't played any music since I repaired it but crossing my fingers.

Luckily I had some spare 216's on hand but I was entertaining the idea of replacing them with ksa1220 and the j79's with ksa2960. Any clever ideas for adapting these to the board? I glanced at the pinout and it seems like they'd have to be mounted upside down relative to sink.

@JoaMat I think I remember you doing this for one or two amplifiers - are they still running without issue, and how'd you mount them?

[JoaMat]

One could say that the legs of BJT is shifted one step to the right. So I just bent the legs accordingly and put a pin header in the left hole and then mount the transistor with desired torque . As I do it the pin header is hold in place by the crossed leg. Solder and it’s done. Few pictures below. Hope they show how I did it.

 

 

 

 

I've modified one T2 and one Blue Hawaii this way. And it works fine.

[nopants]

thanks so much for the pictures, I'll order a few while the amp's opened up

[Pars]

Nice job! A piece of teflon tubing on the crossed leg might not be a bad idea though.

[Remolon]

would be a significative difference in heat transfer turning upside down the BJT and using the other face for cooling?

[Kerry]

I wouldn't do that

[Remolon]

why not, if  the TO126 body is non conducting pastic?

[Craig Sawyers]

I'm just not sure where the silicon is in relation to the package. It *may* be much closer to one face than the other.

[spritzer]

That is exactly the point.  You can just break one open and check. 

[Fitz]

23 hours ago, Pars said:

Nice job! A piece of teflon tubing on the crossed leg might not be a bad idea though.

That's what I'd probably do, but those are pretty clean bends so not really much worry about accidental shorts once installed.

[JoaMat]

I did consider tubing, but the min distance between pins is about the same as for those without crossed legs. As long as I don’t try to stick some test pins in there I think it’s safe.

[Fitz]

What did you do for the first bend ~2mm from the plastic? I often mess those up and end up with the package being the fulcrum when I try to do it that close.

[JoaMat]

I just held the chip with one hand and with a small pliers I carefully bent the pin. After bending 30 degrees or so I took a new grip with pliers moving it a few tenths of a mm to avoid a to sharp bent.

Well, try it – I did ten pieces and all successfully - maybe beginners luck…

[JonChoivo]

On 3/20/2013 at 11:48 AM, Voltron said:

Ugh. I moved my DIY T2 from Mayberry back to SF without incident but was listening tonight and there is a persistent static crackle in the left channel. Same on two headphones and same after switching both sets of tubes from left to right in sequence. Any suggestions?

Hey guys,

Sorry to intrude, but i recently bought a T2 from a prominent and very trustworthy member here, and having just turned it on, i seem to be getting the same problem as Voltron did in march 2013. It came up after 10 mins being on, and stayed that way even after switching the left tubes to the right.

Normally, i'd just send an email to the maker, but i don't think he'll be available due to personal reasons for the next couple days at least. 

I've read the post by livewire and im wondering if its safe to turn on the amp with all the tubes in place, as, Georgep described the transistors in the T2 turning black due to other problems in one of his post. I've switched if off once the buzzing and crackling in the left channel was heard and when i turned it on again after the tubes were replaced, they sound was still there.

Thanks for the help.

Cheers
Jon

 

[Craig Sawyers]

Have you got any test gear - DVM (preferably more than one), oscilloscope etc? The T2 is such a complex beast I wouldn't like to trouble shoot without test gear.

Offhand it could be anything from a fault in the left hand power umbilical to breakdown in a passive component to an active component going noisy, or a bad connection to a tube pin (I have that with one of my input tubes; wobbling it stops the problem. Note to self: must fix more permanently), or something else entirely.

[GeorgeP]

8 hours ago, JonChoivo said:

...

I've read the post by livewire and im wondering if its safe to turn on the amp with all the tubes in place, as, Georgep described the transistors in the T2 turning black due to other problems in one of his post. I've switched if off once the buzzing and crackling in the left channel was heard and when i turned it on again after the tubes were replaced, they sound was still there.

Thanks for the help.

Cheers
Jon

 

At least one piece of advice - do NOT turn the amp on without the tubes. Also, not sure about the reference to me describing the transistors "turning black" - I don't always remember everything I write, but that certainly doesn't sound like something I wrote.

As Craig pointed out there are a number of different issues that could be the cause of your symptom(s). Having a DMM will probably be necessary to sort out your issue. Did you try swapping the umbilicals? Also, check the wiring block in the amp section (by removing the bottom plate) to make sure none of the wires loosened in transit.

[GeorgeP]

I organized a DIY T2 chassis group buy a couple years ago, and I've had a couple people inquiring as to whether I could do another. So putting this out there to see whether there is sufficient interest in doing it again. I would need at least 5-6 participants for it to be viable. Last time the cost of the chassis was $1500 ish, with anodizing, holes tapped, brackets are laser etched faceplates. Before I place any order, in the event there are enough participants, I would need a $200 up front commitment as the machine shop needs 50% at commencement and 50% on completion and I can't have people changing their minds later on. So reply here or PM me.

[luvdunhill]

I might be interested in a set of transformers - if anyone decides to put together a group buy for those.

[GeorgeP]

Thoughts on who? SumR and Paul Houlden (TEK) are the only ones that come to mind. I have had no issues with either.