The ultimate DIY? A Stax SRM-T2!

[n3rdling]

What kinda tests?

[Craig Sawyers]

This might belong in the Stax thread, but did you catch the newest issue of Hi-fi news? They are doing some tests on a Quad ESL as a part of their vintage roundup...

I didn't catch that - but I clearly need to get hold of a copy!

Cheers

Craig

[spritzer]

What kinda tests?

Waterfall plot, FR graph, distortion, sensitivity etc. They did test an old set so they aren't ideal but a 0.1% THD shows they did something right in 1957...

[kevin gilmore]

You don't need a leaf spring. It only moves 270 degress... Four turns of wire around the thing connected to the

shaft and to ground, and you are done. I've actually seen this done a few times.

[Craig Sawyers]

Waterfall plot, FR graph, distortion, sensitivity etc. They did test an old set so they aren't ideal but a 0.1% THD shows they did something right in 1957...

It's the wrong list, but these puppies were launched when I was one, and the pair I'm listening to right now were made when I was eight. Essentially two new treble panels (

[spritzer]

You don't need a leaf spring. It only moves 270 degress... Four turns of wire around the thing connected to the

shaft and to ground, and you are done. I've actually seen this done a few times.

Well this one moves 300

[kevin gilmore]

The final resistors came in today, and the T2 is now 100% complete, all parts including standoff's mounted, and most of the screws in the chassis...

But in the last hour, i got the prototype of the NEW preamp running. First time. Got to lay out the board.

Does unbalanced to balanced, and balanced to balanced with no more than .02db error, and FR of DC to 200khz...

Desperately need to test with lsj109's...

Been a very productive few weeks.

[luvdunhill]

no more than .02db error

that's the hard part huh...

[kevin gilmore]

that's the hard part huh...

yep. But things have changed. I'm not sure anyone needs a tape loop anymore.

Certainly not for a real tape machine of some kind. And if they do, its unlikely to be balanced.

So a full feature preamp these days is a lot different than they were

25 years ago.

[Knuckledragger]

I have an Otari 1/4" 2-track R2R tape deck that has balanced (and only balanced, IIRC) I/O. Of course, I don't really use it. It has its own 19" rack-case and is heavy to Krell-like levels.

[kevin gilmore]

Otari, Ampex, Studer, and Nagra. Those are really studio machines, and very few

made it to homes. A long time ago i had an 8 channel ampex. Took at least 2 people

to move it around. Like the Eidiphor i had, it was completely useless and took up

way too much space. Very hard to find pre-recorded R2R tapes these days, and the

price is silly if you do. So if you are going to be doing live recording you are

going to have to get one of the new all digital things with the built in hard drives.

And again, not really suitable as a recordable media device for home use.

[struts]

Hi everyone, newbie here.

Few things.

1. I went though the BoM x-refing the lists generated by the CAD program with Craig's Excel and the boards fixing a couple of errors in quantities and part numbers and added a sheet which can be imported directly into Mouser to create an order for everyting on the BoM that they stock. Will send to Kevin so he can put it up on the site.

2. I found what looks like a good price ($656) for the RK50 here.

3. Any of the European-based folks have a source that stocks all the screws? Can't find anyone locally with the full selection of imperial sizes.

[kevin gilmore]

uploaded struts spreadsheet.

http://gilmore.chem.northwestern.edu/t2parts3as.xlsx

[kevin gilmore]

If everything goes right (and it probably won't) i should have 5 sets of tops and bottoms by friday afternoon.

Already have at least half of the fronts/backs and heatsinks done.

I know that at least 2 of you want to do your own finishing, If there are any more that want the chassis

unfinished speak up now... Could get a couple of chassis out in a week or two.

(no knobs yet)

[nattonrice]

I'm up for the finishing that you choose to go with.

[Craig Sawyers]

I'm up for the finishing that you choose to go with.

Ditto

Craig

[kevin gilmore]

I'm back to machining the edges of the tops and bottoms. Really does not add that much extra time or expense. The laser cut edge sample i did not like.

Should finish the 3 sets by monday, 3 of the 4 pieces are done.

Without finishing, the current cost estimate for the 2 fronts, 2 backs, 4 heatsinks, 4 angle brackets, 2 tops, 2 bottoms and 2 stax jacks is $987 plus shipping.

No idea how much the knob is going to be yet, the first one i made by hand, need to learn how to use the NC lathe.

[struts]

I'm up for the finishing that you choose to go with.

Ditto.

Craig,

Could I ask if you know of a source for the screws in the UK? I am based in Sweden and have not been able to find a source for the imperial sizes locally. I can order the volume items from McMaster Carr but most of them come in packs of 50 and it's expensive (as well as downright silly) to order 50 of everything when for several parts only one or two are required. Some can undoubtedly be swapped for nearest metric size, but ones that have to fit tapped holes will need to be the right size if redrilling/tapping is to be avoided.

Alternatively if any of the US-based folks would be prepared to put together a bag of the low-volume parts I'd be very happy to pay for it... (bats eyelashes hopefully)

On a related point, Kevin did you say that the default finish would be black? Want to make sure I order external screws in the right colour.

[kevin gilmore]

Well personally i like the look of black, with shiny stainless steel screws. Some may even want to add washers...

[Craig Sawyers]

Ditto.

Craig,

Could I ask if you know of a source for the screws in the UK? I am based in Sweden and have not been able to find a source for the imperial sizes locally.

I've used these guys before Stainless Steel Fasteners, Microscrews, American Threaded Fasteners . They are extremely responsive, and cover all the head styles and lengths in both metric and US thread sizes. If you don't see what you want, get in touch with them - not everything they have is on the website.

I'll be using them once I decide what I need specifically in US thread sizes for the T2.

Craig

[swt61]

Ooh, nice resource. Thanks Craig!

[Icarium]

I'm up for the finishing that you choose to go with.

I'm in the same boat depending on cost and what lower cost finishings are like.

[kevin gilmore]

A milestone was reached today.

I just shipped Inu the top and bottom plates, so he

now has a complete chassis set. (less the knob and a 6 pin stax jack)

So if he hauls ass a bit, he might have his built by CJ2010

On friday the vendor that is doing the polishing and anodizing is picking up two

complete sets of chassis (less the knobs) so production is well underway.

On a lighter note, my first experience with a 4D mill doing the preamp chassis as one

single piece turned the block of wax into a big mess. The machines idea of 90 degrees

and mine seem to disagree

If there is going to be a next batch of boards, i'm planning on a pair of single

piece chassis for my second T2. Everyone needs 2 x T2 !

[Icarium]

I plan on having parts for 2 ! ;p I bow to you on the single chassis element though

[Inu]

ST micro