spritzer

Tubes = valves to the rest of the English speaking world.

Mkey....

Yeah, I wouldn't even try tuberolling this amp. For instance the ES-1/2 should only be used with ECC81's but Mikhail probably thought they looked odd driving the EL34's so used octals instead...

Yup, the SR-007 drivers made out of stiff PCB material encased in a resin frame. That is in turn bolted to a massive piece of aluminum (for a headphone that is) that sits inside an aluminum ring which forms part of the rather unique headband assembly.

Stax mafia doesn't agree. I think I tried a JH13 at CJ though I'm not sure (fairly certain my good friend Douglas made me do it ) but the DSP unit didn't sound as good as a SR-003. It wasn't bad by any means but the bass was just odd to say the least with a definitive coloration. I've also never heard a headphone that can match the spectacular midrange of a well driven SR-003 (yup that includes the SR-007). Rumor has it that Stax are working on a new version which is about damn time given the Mk1 was from 1995 and the mk2 from 1997. I do hope they will fix the fit though as that's what really lets them down. Couple that to the Gilmore portable amp (which we hope somebody can build the transformer for) and it would be a very interesting shootout.

I do have a bunch of them and I might try it with slightly lower rails just to be on the safe side, +/-380V maybe.... I like crazy ideas like that. I want to do a single ended SS amp with an output transformer for Stax one of these days...

That's enough about those inferior dynamics!!! So I've been working on this SR-Omega that needed some TLC. I don't think I've ever posted pics of an empty SR-Omega shell to show why I sometimes call them the tin cans... As you can see the cups are very thin and it is mostly just plastic in there. Couple that to the huge driver and no wonder they get a bit ill tempered at higher volume levels. Far cry from the SR-007 design where the drivers are securely mounted in a large slab of metal. Another insteresting bit is that Stax grounded the metal enclosure through large resistors to the + and - terminals.

You only need to alter the gap between the diaphragm and the magnets a little bit to loose a lot of sensitivity so there could be tweaks done to the drivers you could never spot unless you opened them up. I don't get the benefits of marketing a headphone like this though where a B22 or a Dynahi/Fet are your only realistic options for driving it.

More voltage swing and higher slew rate and the biggest factors.

I can always supply red vodka if it helps my US legal team. Get better soon Al. Yesterday I had a mini-meet here with Stuart which was basically us talking until midnight with about 10 minutes of listening thrown in. Pretty much the definition of a mini-meet... Today I was busy with cleaning up the house and even attempted to sort out all the DIY related parts cluttering up the place. That pretty much failed...

It would limit the voltage to 400V but I've been using them in the BH PSU's for years now with good results.

In terms of high end audio a 3.2:1 markup would be very much on the low side.

Most XLR adapters ground the - signal but that could be causing issues here.

Welcome to the wonderful world of transistors, here one day and gone tomorrow...

If the IC's are shorting out then it could present like that. Have you tried another set?

Here I was thinking Marc had finally lost it, worrying about how fuses sound etc...

You guys could also switch to 230V...

The chassis mounted sinks are simply out of the question and that's that. This is an amp meant to bring close to TOTL performance at a budget price and designed so that anybody can build it.

It's a fully balanced amp but you only have to ground the - input if using it single ended.

As it stands now, we will offer one PSU only for the foreseeable future. There is also no need to keep posting your interest in this project, we only need that once the preorder thread goes up. There will be enough boards for everyone.

I do have a question for the group, would you want a cheap PSU that is good and does the job well or balls to the wall T2 type PSU? The difference in cost will be substantial so it is something Kevin and I are discussing. The CMF70 would work but isn't that way too big? The output resistors (the reason why they aren't normal metal films in the T2, ditto for the Stax amps) but stuff like the feedback line is split up. The boards will be open to everyone and nothing has been decided wrt a group buy of parts. Given the huge logistical nightmare of getting things to me it might not even happen.

There isn't much to the BOM to be honest. All the resistors will be the 1/2W Xicon units we used for the T2 (the Vishay RN60's are only rated for 300V) but you can also use the 1/2W PRP's and other resistors designed for use in tube amps (i.e. with high voltage handling). The values for everything are on the board as well. There are still some things that have to be ironed out like for instance who will handle the distribution of the boards (probably me) and are we going to include any parts with the boards. Not everything can be bought from Mouser so are we going to include those parts in some kind of a kit.

I could deal with Canada but not the US... As for a BOM, it will come in due time.

Wow, the gain of that amp is really on the low side. Even the tiny Stax amps have enough gain for earsplitting levels.

Better amplification does indeed help with this on the SR-007 but they will never be "flashy" about their detail retrieval. It's there but never in your face like some supposedly detailed transducers. The soundstage can also become wast with a good amp but only if that's what the recording calls for.