The ultimate DIY? A Stax SRM-T2!

[Linear]

Could someone tell me the "specs" on the aluminium angle bracket that mounts on the PCBs in the T2?

Is it 1" x 1.5" x 1/8" ? The holes are on 1/2" centers, correct? Are they tapped for 4-40 thread? How far are they in from the edge of the angle bracket?

Thanks!

Linear

[Linear]

four per channel... So that's $240 for the output transistors.

Going to need bigger heatsinks

I wonder how many pieces of justin's new 5 inch heatsink i would

have to buy... Nope, not doing this again. NOT doing this again.

Someone find me a standard heatsink/chassis assembly that can dump about 150 watts of heat.

I might be able to shrink the board to 12 x 12...

Gee, things have been quiet here lately! I guess I'm not just late to the party.....the party is over and everyone is listening to their T2s.

Anyway, after all his hard work, KG deserves to have this heatsink wish granted. Here is what I should have soon:

Material: Aluminum

Dimensions: 4" vertical x 5" horizontal

Number of fins: 17

Perimeter: 61"

Availability: Stock, no minimum order

Cost: ~$150 per 18" length

I don't have any thermal data yet, but comparing the periphery with other products, the calculations say this thing (18" of it), at 120F, should sink over 150 watts! It will probably be less then that, due to the density of the fins, so as soon as I can, I will measure it myself (hopefully within the next week, or so).

KG, I'll send you a 3" sample to try for yourself, after I check it out. Is anyone else out there interested in this for future projects? Maybe the DIY T2 project wore everyone out, both physically and financially!

Stay tuned!

Linear

[Kerry]

Don't worry. I've got a build that I've got most of the parts for and am just getting started. I think there are a few others that haven't finished their builds yet. But yeah, I have to believe that most are blissfully listening to their T2s.

Regarding the angle brackets, they are currently boxed up, but I can get exact measurements next week. I think they were 1.5" x .73" and approximately .33" from the edge. They are not typically tapped and the hole size I use is approximately .132". Sorry I can't be more precise at the moment.

Is that 5" horizontal per heatsink or for two? Sounds massive

[Lil Knight]

Material: Aluminum

Dimensions: 4" vertical x 5" horizontal

Number of fins: 17

Perimeter: 61"

Availability: Stock, no minimum order

Cost: ~$150 per 18" length

That are some huge heatsinks. I'm planning for a little different dimension one, 5" H and maybe 3" V. Still haven't decided the style of fins though.

[Linear]

Kerry,

Thanks, but KG already PM'd me the dimensions of the brackets.

Everything regarding the above mentioned heatsink is for ONE, so it's 10" horizontal for two!

There"s also another version with 12 fins, that's 3.73" horz x 2.75" vert for each heatsink. This smaller one wouldn't give KG his 150 watts, but might work well with T2 power levels (~40W). Approximate cost for this smaller one ~$80 each.

Linear

[Craig Sawyers]

Don't worry. I've got a build that I've got most of the parts for and am just getting started. I think there are a few others that haven't finished their builds yet. But yeah, I have to believe that most are blissfully listening to their T2s.

I'm not sure how many people have now got these running. Last time a poll was done, the count was 5 out of 22 having completed and were listening.

Anyone like to volunteer a current number?

[nattonrice]

Dispite the fact I just copped a $1k fine for the most stupid of things and I'm meant to be writing a thesis soon, I do plan on taking a crack at finishing this in the coming weeks...

Edited March 16, 2011 by nattonrice

[spritzer]

Mine is still about 95% done in terms of assembly with the last parts (RK50 and some transistors) sitting on my desk. Who knows when I'll finally get a day off and can finish this beast...

[luvdunhill]

I am working on casing mine up. I'm having some crazy oscillation though and not sure how to really track down a solution :/ I need to get in the shop. I have everything cut, just need to drill and tap a few holes here and there.

Edited March 16, 2011 by luvdunhill

[Dreadhead]

Mine is still about 95% done in terms of assembly with the last parts (RK50 and some transistors) sitting on my desk. Who knows when I'll finally get a day off and can finish this beast...

your own fault for winning competitions

[spritzer]

Tell me about it. Then on top of that I can't find any good bakers to work for me...

[pedefede]

I am about to order the very last parts soon (trafo, screws, etc) - whenever i get the time (you know ... kids & work ). I also have a DAC-build pending

- but some time soon, i might join you in the buildingproces as well

peter

[Voltron]

Operational units I can recall:

1. KG

2. Inu

3. Craig Sawyers

4. Andy blubliss

Anyone else?

[kevin gilmore]

5. Anonymous but it should be obvious who this person is.

[blubliss]

Jude

[spritzer]

Jude thinks RSA makes quality gear so no...

[luvdunhill]

5. Anonymous but it should be obvious who this person is.

I knew those cases would be perfect for the T2!

[pedefede]

On the Latest schematic for the PS, there are two types of 0,1uf Caps:

C26-29 for decoupling the 100uF caps (before ref102)

(these seems to be located on the PCB between the ref102 and op27)

C30-33 between the 2sc3675 and op27

These seems to be added later on.

- And i cant find any spot for them on the PCB ?!?

- Nor are they meantioned in the BOM ?!?

Anyone got an explanation?

[Craig Sawyers]

On the Latest schematic for the PS, there are two types of 0,1uf Caps:

C26-29 for decoupling the 100uF caps (before ref102)

(these seems to be located on the PCB between the ref102 and op27)

C30-33 between the 2sc3675 and op27

These seems to be added later on.

- And i cant find any spot for them on the PCB ?!?

- Nor are they meantioned in the BOM ?!?

Anyone got an explanation?

Check back through this thread for modifications on the power supply. In fact I think I posted a summary of mods, to wich KG added one or two I had forgotten.

[swt61]

I am working on casing mine up. I'm having some crazy oscillation though and not sure how to really track down a solution :/ I need to get in the shop. I have everything cut, just need to drill and tap a few holes here and there.

Don't even think of putting that thing in DIY never never land, before I get a chance to listen to it!

[wink]

Dispite the fact I just copped a $1k fine for the most stupid of things and I'm meant to be writing a thesis soon, I do plan on taking a crack at finishing this in the coming weeks...

He must have been speeding or getting into public mischief to attract that fine.

The only viable alternative s that he's been hit with a fine and an apprehended violence order for stalking the employees at Len Wallis Hifi with a view to getting a loan of their Stax O2 when he gets his T2 built.

Chatting up the secretary got him nowhere....

Poor Tom. That's what you get when you engage in tomfoolery......

Edited March 18, 2011 by wink

[Kerry]

Here's a new amp I just did based loosely on the T2 topology. I was trying to meet a $69 challeng. Close, but fun just the same. I built it for the NYC head-fi meet have a picture of it here:

Here's the schematic for it. Sounds pretty good, but there's a bit of tweeking I need to do. I think I'm going to raise the power up a bit (currently 250mA per balanced leg). The heat sinks will take it, but I need to modify the power supply a bit.

Thanks to Kevin for his pointers

[jgazal]

Here's a new amp I just did based loosely on the T2 topology. I was trying to meet a $69 challeng. Close, but fun just the same. (...)

Here's the schematic for it. Sounds pretty good, but there's a bit of tweeking I need to do. I think I'm going to raise the power up a bit (currently 250mA per balanced leg). The heat sinks will take it, but I need to modify the power supply a bit.

Thanks to Kevin for his pointers

Which input JFETs have you used in the challenge version? LSK170? 2sk170?

Edit: Forgive-me, I have just read it that it is 2sk170

Edited March 21, 2011 by jgazal

[spritzer]

I've been turning on the T2 PSU in steps these last few days and it almost blew up in my face. The -260V supply went into meltdown mode and the 680uf/450V cap was burning hot after running for about a minute. Now comes the utter joy of figuring what went wrong...

[blubliss]

Sorry to hear Birgir