The ultimate DIY? A Stax SRM-T2!

[jose]

On ‎30‎/‎04‎/‎2018 at 5:51 PM, mwl168 said:

@ Kevin and Kerry; 

with all these great work and progress being made, will there be a second generation T2 soon that makes use of these advancements and current production parts and maybe a bit smaller in size? I would be happy to organize a GB for it.

Really, there's no interest in a T2 "version 2.0" ?

 

[GeorgeP]

39 minutes ago, jose said:

Really, there's no interest in a T2 "version 2.0" ?

 

Guessing that is the case because if you want to build a T2, you can with the existing boards (albeit with a higher parts cost). The only thing I could see that might be worth while updating would be the power supply, but even then.

[nopants]

personally I'm more interested in new designs at this point, but I might be biased

DC Megatron pls

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[jose]

I was thinking on a version with current components. Not a clone, rather an improved version.

It's the same thing that happened with the BH. Why not with T2?

[GeorgeP]

6 minutes ago, jose said:

I was thinking on a version with current components. Not a clone, rather an improved version.

It's the same thing that happened with the BH. Why not with T2?

The DIY T2 is the improved version of the Stax original. From what I understand, the newer/other versions that for example Joamat and Kerry have made are not necessarily improved versions of what Kevin did, but rather use some more affordable and more easily obtainable parts.

I suspect that the interest in building this newer version will still be limited as the newer parts probably only shave $300-$400 off the parts cost of building the T2 - and since it would still remains a mega-buck build, what is an extra $300-400? And it is inevitable that those newer parts will soon be hard to find as well.

 

[jose]

Maybe you have right but for example I don´t want to spend time found obsolete parts or checking if my sand is a fake or not. One thing I have very clear is that I would never clone the box for example and presumably this is one of the most expensive components. I doubt that Dr. Gilmore wants to redesign the box.

For other hand and following your way of thinking, for example I wouldn´t have a BH since the original has obsolete or hard to find components. Thanks to Dr. Gilmore and his latest revision I have an amplifier that otherwise would be impossible to do (for me,  of course I suppose that it will be much easier for you).

I do not know if I explain myself correctly and I do not want to offend anyone either. It's just my point of view.

However, seeing that there are so many "buts" maybe a ver 2.0 is not a good idea.

 

[JoaMat]

I believe ver 2.0 is taken – Kerry’s shrinked smd…

[Kerry]

There are a lot of great ideas in here for various modifications, it's just a very labor intensive activity to pull it all together.  

I agree with George that your best bet is going with the currently available boards.  It's a supported board which is part of the problem on something new.

[jose]

Thanks for your replies. 

[Whitigir]

On 5/22/2018 at 10:41 AM, GeorgeP said:

Guessing that is the case because if you want to build a T2, you can with the existing boards (albeit with a higher parts cost). The only thing I could see that might be worth while updating would be the power supply, but even then.

You can dual power supply  

[Kerry]

I've tried using golden reference HV supplies for the T2, but had some issues with negative rails as well as the current limiting when an issue occurs.  I ended up reverting back to Kevin's original design. 

I will spend some more time with this in the future.  My current GR HV mini board include depletion mode MOSFETs for current limiting in front of the GR HV supply similar to Kevin's T2 design. 

I'm also experimenting with a couple of ideas on how to enhance the current limiting on the GR HV (in case of a short), but need some more time for testing and $$$ for parts (... and a blast shield)  

[kevin gilmore]

Heavy plexiglass shield absolutely required, rounded is better

[swampsong]

Hello everyone, i'm just getting started on trying to build a T2, picked up the boards, transistors, and a chassis set.  I've been reading through this thread for the last week and really enjoying it but one problem is all the pics that Kevin posts are no longer on his server.  I understand he retired and moved his files, and i have found two of the archives at these locations:

https://drive.google.com/drive/folders/0B_iJFfZStuVhSE5nOHBVdTByR1k

https://drive.google.com/drive/folders/0B7egryukiT7_TFlEQlBRejdVdDQ

But I couldn't find any pics. I guess i don't really need them but it would be great to see what he is posting about...

Thanks everyone

-James

[swampsong]

Okay just finished the thread i see those early pictures aren't so important, but what a great thread, just received my chassis, board set, and sand... Mouser order is delivering today... The umbilicals were pre built but i'm going to check all those out.... a few parts here and there seem to be hard to find... mainly the six 680uF/450v caps... and zener 130... But i'm still researching so i'm sure i'll find something.... never built anything like this before but that is the whole point :):) Anyways great thread, going to read it again while i'm on vacation this week

 

 

[nopants]

the string just needs to add to 580

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[swampsong]

oh okay, thanks for the tip, i'll read about that tonight

[swampsong]

Okay i need to order the transformers, it looks like SumR is the place to use if you are in the US, I have some notes Kevin posted on getting them built from 2010:

high voltage transformer x 2 are needed
diameter 3.5 inches height 1.7 inches you can actually go up to 2.5 inches high, and slightly wider

full load voltage---- regulation--- Iac--- off load

475 --- 15.04 --- .13 --- 546.4
285 --- 10.53 --- .06 --- 315
75 --- 10.6 --- .06 --- 82.9

filament transformer x 1 is needed
diameter 3.5 height 1.6

30 --- 13 --- .5 --- 33.9 Center tapped
6.3 --- 14.29 --- 1.5 --- 7.2
6.3 --- 14.29 --- 1.5 --- 7.2
6.3 --- 14.29 --- 4.0 --- 7.2
6.3 --- 14.29 --- 4.0 --- 7.2

I sent SumR the specs they asked this in return:

Do you require single primary or dual and what voltage do you require?

What do you guys think? I have a lot to learn i'm sure but i would like to get these ordered correctly the first time.

Thanks for any help,

-James

 

 

 

[Pars]

Dual primaries would allow you to support both 120 and 240v applications. I always use dual, but wait for Kevin or Spritzer, etc. to comment in case there are any special considerations...

 

 

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[swampsong]

oh okay interesting...

 

[kevin gilmore]

All the SumR transformers I bought were universal voltage.   100,120,200,240  dual windings, one tap per winding

They should already know exactly what these transformers are.

It would probably take me a while to dig up the original quotes.

Edited July 19, 2018 by kevin gilmore

[swampsong]

Don't go to the trouble i'll let them know, i was thinking they might have remembered making them before, thank you i'll see what they say

[Skooby]

Bought my set of DIYT2 transformers from Richard a few months back, just tell him the Gilmore DIYT2 set (http://primroseaudio.com/transformer-designs/)  

*** He gave me only a single 117V primary ***

Edited July 20, 2018 by Skooby
clarifying

[swampsong]

Okay cool i'll send that information to them as well, very useful, thanks

[swampsong]

From SumR:

The only versions we have done this year were dual and single primary.

For dual primaries (110/220V) price would be $90.30.

For a Universal primary would be $107.00

Please let us know what you decide.

So, I"m thinking dual primaries are okay in case i ever want to switch it? PARS said he always goes that way... That is probably the way to go right?

 

[kevin gilmore]

dual primaries are fine everywhere in the world except japan.