[paxeaxe23]

Thanks Beefy, after taking a second look, I see what you mean.

Before I mount the zener strings, I have another question. I'm going to use two Triad transformers as from the BOM for the SS version. There has been some discussion on needing to have 300V Zener string for the 250-0-250 Transformers. I do have a few extra 100V zeners. I sthere any advantage/disadvantage of using 3 x100V zeners instead of the 2 x100V and 1 x 91V Zeners for me.

Thanks again

 

[BoilermakerFan]

Quote:

Originally Posted by tomytank /img/forum/go_quote.gif @BoilermakerFan It's 3mm perspex. I'm using only what I've got, unfortunately, a hot gun with the perspex clamped upright into a wood bench. Measure, mark, secure. Being very careful with the distribution of the heat from the nozzle. I heat and wait for the perspex to sag, then bend and clamp with an additional wood brace, until cool.

No option to put it in the oven at 300degF-350degF (150-175degC)? You could probably take it up higher from there, but start lower, around 200degF and slowly bring it up. You can then move it quickly to the workbench and add more heat to the bend area, but you've pushing it too much at a time when it's cold. 3mm is actually really easy to bend if you take it slowly. Clamp it horizontally on the bench. If you don't want a 90deg. bend, lift up or raise the back side with spacers to get to your approximate angle when the piece drops vertically down off the bench by gravity. Heat the piece as evenly as you can, but have the approximate bend line a little over the edge of the bench. Then heat it evenly and let it drop 1-3cm at a time, and heat a wider area of the Perspex in order to relieve the build up stress risers in the plastic. You have to relieve the stress further to each side of the bend than you think otherwise it will keep cracking as it cools or as soon as you handle it which causes the slightest stress to the material.

 

[Lou Erickson]

@tommytank:

Good call! After all my screwing around, I had managed to blow the fuse in my meter. There's a spare, and I'll have to get some more.

@runeight:

I was so careful when reading the pages, and still got it entirely wrong. A google search for the pinout, or to use the sheet off Mouser instead of the more complex (and apparently irrelevant) one from Fairchild themselves finds a very different pinout, which reads sensibly.

When measuring, I get a value which starts in and then begins dropping... should I use the initial value, or wait for it to stabilize? (Will it stabilize?)

 

[fierce_freak]

Does anyone have a cheap pair of pro bias stats for testing that they'd be willing to let go of?

 

[pabbi1]

I always use electrets (SR-40) just to keep bias out of the initial equation - and, very cost effective.

 

[TimJo]

After careful measurements from the DMM, I just plugged my 404LE's in, putting trust in the design. It worked.

But maybe that's foolish, I'm not sure... It's true I always test a dynamic amp with apple earbuds. Hmmm...

 

[Emooze]

Quote:

Originally Posted by paxeaxe23 /img/forum/go_quote.gif Thanks Beefy, after taking a second look, I see what you mean. Before I mount the zener strings, I have another question. I'm going to use two Triad transformers as from the BOM for the SS version. There has been some discussion on needing to have 300V Zener string for the 250-0-250 Transformers. I do have a few extra 100V zeners. I sthere any advantage/disadvantage of using 3 x100V zeners instead of the 2 x100V and 1 x 91V Zeners for me. Thanks again

If you are using the Triads, you don't need to do the 300V zener string. My SS is working perfectly with the Triads and a 291V string. I'm not sure if there is any benefit for doing one over the other though.

 

[runeight]

Quote:

Originally Posted by Lou Erickson /img/forum/go_quote.gif @tommytank: Good call! After all my screwing around, I had managed to blow the fuse in my meter. There's a spare, and I'll have to get some more. @runeight: I was so careful when reading the pages, and still got it entirely wrong. A google search for the pinout, or to use the sheet off Mouser instead of the more complex (and apparently irrelevant) one from Fairchild themselves finds a very different pinout, which reads sensibly. When measuring, I get a value which starts in and then begins dropping... should I use the initial value, or wait for it to stabilize? (Will it stabilize?)

Use the initial value as soon as you get the reading. Try not to heat the devices by grabbing them with your fingers.

 

[luvdunhill]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif Use the initial value as soon as you get the reading. Try not to heat the devices by grabbing them with your fingers.

This is definitely the way to go about it. It's possible to pick up, and plug the device into a protoboard without using your fingers, it just takes some practice. Also, avoid sitting under an HVAC duct in your house

 

[Sathimas]

The boards 99% finished, only the matched transistors are still missing.
(A friend does this for my as he has all the equipment at work)

Now everything could be ready for testing by tomorrow or so - but the company where I ordered the transformer called today to tell me they made a mistake and forgot the center tap.
So now its only a 500V transformer...

The customer service will call me later this day to set the next steps ...

Whish me good luck that the third try to get a fitting transformer will be the last!




I put the boards there to make them familiar with some of my favourite records :-D

 

[fierce_freak]

lol, nice

 

[Beefy]

Well I ordered my FPE panels last night...... should have them in just over two weeks. So in a three week time frame my Exstata should be 100% done!

 

[Scooba]

I hate to intrerupt again. Does anyone have a spare set of PCB's ? Please ?
(I have already asked Alex, and he does not have any left).

 

[macm75]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Welcome to the club - hope you enjoy the stay.

It's officially alive!! I listened for about an hour and very much like what I hear. Like many of you and audio, I'm not easy to please but right off the bat the eXStata is proving to be a fantastic amplifier. I'll admit I've had these SR-303's for three years now and they have been played for merely hours. I've built 3 versions of Andrea Ciuffoli amp design and was never really pleased. Thought about selling them (303's) many times, would have taken too big a $ hit and kept them. Alex's amp saves them (although Alex's amp also kept me from completing my Gilmore "All-Triode" amp - should have a comparison soon).
No matter what I give it, I find the soundstage, instrument separation, air, and, in particular, layering of sounds to be absolutely superb. Amp is dead quiet and provides a black background for the music. I'm also pleased with the weight of the notes, dynamics, and detail from top to bottom - given the 303's, hard to believe one could get more out of them. For better sound, a source or headphone upgrade would be required - this amplifier is the strong link.
I'll have more to say in the upcoming weeks. Real case is in progress and my All-Triode amp (it actually ran for an hour before a part blew up on the PS) will be complete soon. For now I cannot thank Alex enough for the design, documentation, and PCB’s - a tremendous effort and a pure gift for our enjoyment.

 

[pabbi1]

Welcome aboard! I have found it really raises the lower Stax models (considerably), and takes nothing away from the upper ones, well, the ones I can comment on somewhat objectively.

Congratulations - looks like I'm sending the proto to yet another person to join the club, so maybe he'll chime in with some impressions this weekend.

Oh, and I'll have a new source by then...