The ultimate DIY? A Stax SRM-T2!

[Helium]

Ok, I checked BOM and availability of parts here and there and it seems feasible to build but at enourmous price, almost prohibitive for own use.

I guess ttl quantity of listed obsolete parts in whole universe is enough to build 10 units more of this thing. Maybe 15 (provided they are not 'wasted' for other projects). Then they will be depleted forever.

I may be missing somehow but last year you mentioned:

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diy-t2 with current production parts testing now obsolete fets 2sj79/2sk216 replaced with ksa1220/ksc2690 and 2sa1486 replaced with stn9360

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How about the progress? I guess board have to be redesigned to accomodate new parts.

Edited September 27, 2017 by Helium

[spritzer]

I have enough parts on hand to build at least 80 T2's... 

[Inu]

   On September 26, 2017 at 1:42 PM,  kevin gilmore said: 

Thank you so much.

Curious, japanese fonts are used, who touched 

 

> I never touched...

[Helium]

Yep I'm working for Japanese company, and my eyes got used to seeing that)) whoever edited the file has OS with japanese language pack installed.

[Skooby]

Are these valid DIY T2 tranny specs?

30-0-30/500mA, 2x6.3V/1.5A, 2x6.3V/4.5A

Two of 485V/150mA, 285V/60mA, 75V/60mA

Thanks!

[Whitigir]

On 8/21/2009 at 7:17 PM, kevin gilmore said:

teflon sockets only it is. Actually looks a bit better this way.

 

Anyone that can build a dynahi can build this. If you stuff all the

parts in the right place and can do a really good job of soldering

it should be a snap.

 

http://gilmore.chem.northwestern.edu/staxt2connexonlyrev0-2.bmp

ground plane removed for picture otherwise it wipes everything away,

components that don't look like they have a lead connected are connected

to ground

 

http://gilmore.chem.northwestern.edu/staxt2rev0power-6.bmp

 

i even have a bill of materials. (first time ever)

so i have a clue how much its gonna cost, and how many more parts to buy.

 

231 semiconductors makes this the most complicated headphone amp ever.

Visiting the thread again! Hope the T2 is as straight forward and easy as said above !

how many people has successfully get their blue PCB boards up and working ? Beside the 1 missing trace, am I missing anything ?

[Rossliew]

There's a beautiful T2 for sale over at HF..believe its a Kerry build.

[Whitigir]

Damn, that is a beauty...why would anyone want to sell it ? :(.  Nothing will ever be as good.  But let’s get back to building a T2

[Whitigir]

So, I found the Post from G600 about the leaked trace on the Power Supply.  This is AHN2212 Relay place, isn’t it ? I don’t think I have this leak, and if this is the only problem, then I am safe to use this board ?

 

 

[G600]

Yours is safe.

But just take a careful look before starting populating the Beast.

[Whitigir]

Has anyone else been using 2sk216 from Renesas Audio ?

Edited October 6, 2017 by Whitigir

[GeorgeP]

The original was made by Hitachi. Renesas is the good. Not sure of any differences, but I suspect if you are seeing this "readily available" its because fakes are readily available.

[Whitigir]

7 hours ago, GeorgeP said:

The original was made by Hitachi. Renesas is the good. Not sure of any differences, but I suspect if you are seeing this "readily available" its because fakes are readily available.

Thank you !  And perhap the scariest of building T2 is the combination of both, expensive parts and “fakes” sands.  I have been trolling around and asked a few other members who finished their T2 on sourcing parts.  I was told that 2sc3675 can be found here as well.  If anyone look for them

http://www.wakamatsu.co.jp/cgi-bin/psearch.cgi?page=0&word=2sc3675

2sc3381 can be found here....and I also have some from Justin as well .  Justin had a few orders couple months ago too. BDent also have some but pricy

http://www.classicaudioparts.com/index.php/electronic-parts/toshiba-2sc3381bl-transistor.html

Classic Audio on left, Justin on the right.  Using the cheap Ebay tester has seen authentic to specs so far.

 

 

 

Edited October 6, 2017 by Whitigir

[Whitigir]

On 6/27/2017 at 9:05 AM, s_r said:

As I suspected, the sporadic noise hasn't actually gone for good. I've tried reflowing more joints just in case but that didn't do it. If it helps pinpoint things at all I've noticed that the back right EL34 has a tendency to physically ring. Even if the tubes are swapped around, the tube in that position starts to ring. I've tried putting in mullards, which didn't ring, so maybe the mesas are just more susceptible to ring as a result of whatever is going on.

So, in the end...what was the problems that you have found ?

[Whitigir]

Has anyone used JJ E88CC  for 6DJ8 ? I rather prefer it than trying to find some vintage tubes at horrible prices

Edited October 9, 2017 by Whitigir

[Whitigir]

On 3/27/2011 at 10:49 AM, spritzer said:

It appears I have good news on the T2 front. Today is my first day off in a month and a half so I'm running at approximately 50% which is way more than is the norm. The first thing I did was to go over the PSU and everything was as it should be, all resistors matched the schematic and everything was properly soldered. So that wasn't the issue I checked the transformers and lo and behold, I didn't get any resistance readings on the 485 and 285 windings... Turns out SumR fucked up the data sheet so violet*/gray were listed for the 485VAC winding but it is supposed to be gray/blue. Ditto for the 285VAC windings, they listed blue*/green but it really is violet/green. Here are some pics of the other transformer under test but the resistance on the offending transformer is the same:

 

 

 

Needless to say I'm not happy but I'm more angry at myself for trusting the datasheet... Now I just have to fix the leads and hook everything up for testing.

 

This scares me....just went ahead and measured my SummR transformers.  I didn’t get any data sheet, but only given email details which were just as Is.....I thought I would ask for confirmation to double check....but thanks Birgir, I put them through my DMM just for the hell of it.

I had the funny feeling though...was hoping that the Primary winding would not be messed up....tested it too....

all turned out great! Unloaded

T1  and T2 for Hv trans

 601 and 598 

352 and 350

94 and 93

 

Edited October 10, 2017 by Whitigir

[Whitigir]

Thanks so very much Mr.George !

i got the chassis today, and they are so beautiful, I just want to eat it....it is like adult version of Cookies ! Time to gets some drinks

Excellent packaging !

Edited October 12, 2017 by Whitigir

[johnwmclean]

Really nice!

[s_r]

On 10/7/2017 at 11:25 PM, Whitigir said:

So, in the end...what was the problems that you have found ?

I wish I knew. I've since tried removing the thermal paste from all the sand on the right channel in case it was shorting somewhere. No change though. Next thing I could try is putting .1uF bypass caps on the voltage set resistors in the PSU. If that doesn't do anything my next WAG is the RK50 being responsible somehow. Desoldering the RK50 seems like it'd be a huge headache, and a risk to damaging the solder points (the pins were a snug fit even before soldering them in).

[spritzer]

I've had to desolder a RK50 and it is easy with a desoldering gun.  You can get a cheap one which costs a fraction of what the RK50 costs... 

[s_r]

It's a good thing I have a decent hakko desoldering gun then. I'll take your word for it, but I'm just worried about taking the pads with it as I lift the RK50 off.

[spritzer]

Setting the right temperature is key but even if you lift a pad, it's not that bad here.  Easy to jumper everything as needed. 

[Whitigir]

On 6/30/2010 at 3:16 PM, Craig Sawyers said:

Finished the power umbilicals today (getting everything prepped for the arrival of casework in due course). Forgot how fiddly it was to wire up Amphenol mil spec connectors.

 

I guess it took an hour or two to cut the wires precisely to length, twist the heater wires (to reduce hum radiation), pull though mesh sleeve and adhesive lined heatshrink the ends. Then cutting up neoprene sleeving to the correct length (around half an inch). All told maybe 4-6 hours for the pair.

 

After soldering one end I did a pin to pin check to eliminate wiring errors (one found and corrected), and a leakage check to ensure that there were no faults in the ubmilical or the connector. Used an AVO mega-ohm meter, which has a switchable voltage up to 1kV and measures up to 10Tera-ohms (10^13 ohms). Well the leakage of my test setup was 10^11 ohms, so all tests were relative to that (to get much further the whole set up has to be on a teflon sheet). Every pin was checked to every pin, and it was all well over 10^11 ohms at 1kV for every wire to every wire - which is an excellent result. Very happy with that.

 

I made them up at 4 feet at KG's suggestion - that allows the units *not* to be stacked, so helping heat build up.

So, I am curious as the amphenol connectors body are insulated....unless scraping off the insulation (bottom body to faceplate into the screws going to chassis) to install the braided mesh for shielding to Ground to reject EMI/RFI as the braiding and or twisting is merely enough.....what do people do for shielding purposes ? Thanks very much

Edited October 17, 2017 by Whitigir

[GeorgeP]

You don't need any shielding. I have made umbilicals with and without, including bundling the heaters separately and could detect no difference.

[Craig Sawyers]

7 hours ago, Whitigir said:

So, I am curious as the amphenol connectors body are insulated....unless scraping off the insulation (bottom body to faceplate into the screws going to chassis) to install the braided mesh for shielding to Ground to reject EMI/RFI as the braiding and or twisting is merely enough.....what do people do for shielding purposes ? Thanks very much

Wow - well done digging that out! I'd lost track of the years that had passed since I built my T2