The ultimate DIY? A Stax SRM-T2!

[kevin gilmore]

Maybe if you knew how to design and lay out an amp, you wouldn't have such a hard time finding parts now would ya.

Feel free to lay out the board as you see fit. If yours is better, i'll make that one

instead.

Is there a schematic abouts anywhere I can look at, also PSU requirements?

hot off the presses...

http://gilmore.chem.northwestern.edu/singlehoures1fix2.pdf

[Smeggy]

Cool, thanks muchly!

[Smeggy]

Just been looking over the ES1 and was wondering if there's any reason the four triodes couldn't be replaced with two twin triodes and replace R5-R8 with a pair of 2k resistors across the tabs?

Bear in mind I know shit about this, so humor me

[guzziguy]

..., so humor me

We always do.

[kevin gilmore]

Just been looking over the ES1 and was wondering if there's any reason the four triodes couldn't be replaced with two twin triodes and replace R5-R8 with a pair of 2k resistors across the tabs?

Bear in mind I know shit about this, so humor me

The 4 input tubes are actually 2 x 6sn7's and are twin triodes.

However the original circuit was 2 x 12ax7's which have more gain.

Fact is that as shown the amp just barely has enough gain to

work. In fact its a good idea to change out the 1500 ohm resistor to 1k ohm

to bump up the gain a bit.

If you do replace the front end with 12ax7's then you need to lower the B+

to that section because 400 or 450 is too much. There is another power

supply in the T2 that would be great for 300 volts...

Edited September 13, 2009 by kevin gilmore

[Smeggy]

cool, I wasn't sure I was reading it right. Looks like it could be made very small as well, aside fom the psu/transfos.

I might have a go at this when I'm a little more practced

[jgazal]

let me be slightly more specific.

something like the old vampire right angle single rca jacks, circuit board mount.

justin's are not right angle..

The connex one is the only one currently available, and it is way to long, i.e.

i have to mount it 1 inch back from the circuit board edge to get it to fit the

backpanel.

The cardas is even longer as a dual.

Is this what you are looking for?

Rapid Electronics - Cables & Connectors

Sorry, only UK... And they seem quite expensive...

[spritzer]

I've spent the last few hours searching for PCB rca connectors and coming up empty. The single Cardas GRFA might fit but I can't find any other nice ones which aren't branded Vampire. Perhaps we should just have the RCA's on short lead wires?

The stock T2 supply is not RCRC. In fact its just diode bridge into

capacitors...(balancing resistors and discharge resistors don't count)

My bad... it's not like the schematic wasn't within reach...

cool, I wasn't sure I was reading it right. Looks like it could be made very small as well, aside fom the psu/transfos.

I might have a go at this when I'm a little more practced

If you ever want to tackle this Gary just drop me a line. The ES-1 rebuild has been on hold for a while now but I'm about to get cracking again and solve those damn gain issues (one channel is lower then the other in SE mode) and add the second 5k pot for the front end.

You can also build a smaller version (ECC83, ECC99 and 6S4A's)...

Is this what you are looking for?

Rapid Electronics - Cables & Connectors

Sorry, only UK... And they seem quite expensive...

Those appear to be Vampire Wire units

[Smeggy]

Nice Birgir, I'll be in touch about it later.

[pabbi1]

Pabbi linked a picture of one at some point and I think he's the only one that's built one? Talking with luvdunhill who I believe designed it? He says that its actually more like the woo amp WES or was it the GES? I forget which one its like... but yeah it's a whole other direction.

If you consider the BH to be one tangent and the Vulcan to be one tangent I think the T2 is somewhere in between sharing like 50-75 percent overlap with the BH... but with more tubes to roll and other differences.

Anyway I'm not technical so correct me if I'm wrong?

Well, Marc is the designer, where the design goals were BHish, but with 6s4a tubes. Marc SHOULD have his built... mine looks like:

Now, what Peter was referring to is the Poor Mans stat amp (~$300), which looks like, but not quite there, though in final proto, with one up and running, one damn close, another by the weekend, well, then mine, which is always the problem child. -=I=- am DIY's lowesr common denominator - sorry Smeggy.

God damn, by spirits are flagging, and I still have to fix one channel on my BH - worse that Mikhail, except I'm just fucking myself over.

[nattonrice]

The poor man's stat amp is by no means poor!

That looks really rad

[swt61]

Hah! Love the double decker design Al. And that Stax plug is fantastic!

[Smeggy]

those do look good, can't wait to get my mitts on the poormans. Maybe I can let my stax box go after that.

[deepak]

Is "poor mans" relative to what electrostat owners are used to forking out?

[kevin gilmore]

what to do?

http://gilmore.chem.northwestern.edu/sockets.jpg

If i make the octal sockets flush with the top of the amplifier

then the 9 pin sockets are .23 inches below the top of the amplifier?

If i make the 9 pin sockets flush with the top of the amp, then i have

to make the holes for the octals bigger and they stick up .23 inches?

Or push them both thru the top and make different sized tube rings?

any suggestions...

would rather not machine up some tube rings..

[luvdunhill]

what to do?

http://gilmore.chem.northwestern.edu/sockets.jpg

If i make the octal sockets flush with the top of the amplifier

then the 9 pin sockets are .23 inches below the top of the amplifier?

If i make the 9 pin sockets flush with the top of the amp, then i have

to make the holes for the octals bigger and they stick up .23 inches?

Or push them both thru the top and make different sized tube rings?

any suggestions...

would rather not machine up some tube rings..

use ceramic standoffs to add some height to the noval sockets?

[kevin gilmore]

look at the pictures again... the pins on the noval aren't anywhere near long

enough.

If i make the holes real big for the octals i can push them thru to the threads

and gain another .12 inch.

[kevin gilmore]

The transformers just arrived

http://gilmore.chem.northwestern.edu/transformers.jpg

precision machined mounting bracket behind them.

[spritzer]

Woot!!!

[luvdunhill]

If i make the holes real big for the octals i can push them thru to the threads and gain another .12 inch.

yes, that's what I meant. I have a whole sack of mil-spec ceramic standoffs around here somewhere... They cost a fortune to buy these days through Mouser, etc.

[Dusty Chalk]

Hawt.

[kevin gilmore]

So the size of the RK50 dictates positioning too.

Its actually perfect flush mount for the noval's, and the

octal will be .230 high, and i'll make .250 rings.

Or maybe plates, ray style

luvdunhill, what is the thickness of the ceramics you have (need to be .09 id) and .25 long.

and do you have 600 of them that you want to sell?

[nattonrice]

And that Stax plug is fantastic!

I totally missed that!

It looks complete class compared to the WPI job.

Much more secure mount to boot.

[swt61]

I totally missed that!

It looks complete class compared to the WPI job.

Much more secure mount to boot.

I was being a clown, by patting myself on the back. I built that jack with help from a really cool jig Marc designed. It is a fantastic jack though, and it really has a quality feel when inserting the Stax plug. If you knew Marc (luvdunhill) like many of us do, you'd expect nothing less.

I hope it's safe to out your plug Marc, considering I already did so quite a while back.

[spritzer]

I've been plugging the plug like crazy too...