spritzer

"One of us, one of us, one of us...." Congrats and and damn straight in comparison to the HD800.

Isn't this the trend with all Audio-GD products. Noobs think they are the bees knees but seasoned ears expose them for the subpar crap they really are?

I looked into driving from Boston to Chicago for CanJam but quickly abandoned it. 8 hours in Iceland lands you on the other side of the island...

Yup, I think Edwood did that. I want to do something similar with amps but not rely on double blind. I want to expose the "mmmm pretty" bias...

The resistor is indeed there just to protect the user. As for the cap, most of the older amps have it. I've been working on a SRM-Xs today (introduced in 1990) and it has it, same as the SRM-1 Mk2 PP (circa 1990 as well). I do think it is there just to provide some extra filtering as for instance in the SRM-Xs the bias supply is taken directly off the B+ rail. With the minimal filtering found in the amp it should help.

There is one more problem with DIY, it often costs less which is why it must sound worse. I've always wanted to test just how much perceived value is an effect with this stuff...

I've only ever understood half of it...

Note from KG:

This is indeed a bad situation compared to say the UK where Stax is everywhere, in every magazine and selling a lot of gear. As for the transformer, the SRM-006tA can be modified to run on 117V but it might be hard if they cut the higher voltage wires on the transformers.

To powdercoat a piece like that here wouldn't cost more than 20$ and that's with 25.5% VAT.

Mixed impressions don't surprise me. When you run the tubes this far outside of their comfort zone they will become unpredictable to say the least.

Indeed good sir.

Any normal amp would run the outputs in series (as in the amp outputs are the same) and only the bias supplies are different. Now the A-10 is a steaming pile of fail and Ray is a half-wit so anything could happen. If the headphones work on the BHSE then the A-10 would be my first place to look for faults, same with any other amp/headphone fault situation.

Not sure. This was all in the early 90's but somebody might have posted the documents somewhere.

...and then get sued by Magneplanar just like Apogee...

Some updates to the Stax DIY amps. As soon as I get the SRM-727 here then I'll post a guide how one goes about altering the feedback loop but for now we'll have to settle for something less fun. SRM-Xs These are pretty uncommon as they were only sold with the SR-80Gold headset and being electret units, have no bias supply. Now this being Stax it doesn't mean there isn't a space for one or two on the board. Now this design is very different from the SRM-Xh I modified above even though they share the same chassis and there were even some SRM-Xh's which used this PCB. Just take a look at these pics: The core design is similar but very different layout and same goes for the output devices. The Xs is a bit unique as it uses Mosfets for output devices, 2SK216's to be exact which can be found in the Blue Hawaii as well. Now the whole point of me writing this was lack of a bias supply in the SRM-Xs. In the pic above it should be between the large blue caps and the transformer. The spaces are for 3 caps (10mm pitch), two diodes and one resistor plus the terminal for the connecting wire. For the caps I just used what I had at hand, 10nf Wima caps rated at 630V as the exact value of the caps isn't important. You can also leave out the one next to the resistor as it isn't really needed. Now for diodes I used UF4007 (1N4007 would also do just fine) and the resistor is the standard Stax 4.7M (I used 5M). This is just a voltage doubler off the B+ so the bias isn't exactly correct but it works just fine into my SR-404. Here is also a teaser for something I'm working on, converting a SRM-1 Mk2 to balanced operation. I found this upgraded PP unit in Japan and it was missing the main heatsink/output transistors and in a pretty sorry state inside. These will be replaced but the main attraction is that these amps sound great, are fully DC-coupled and are a doddle to convert to balanced operation. Just replace one resistor on the board (910K) and add one resistor beneath the board (1K) and you instantly double the voltage swing of this thing.

Yup...

Stax did experiment a lot with the bias supplies and they still vary a lot from amp to amp. I can't say I'm a fan of having a cap after the ballast resistor though... As for output caps, the Woo Audio GES (which is the all triode amp Dr. Gilmore designed and can be found on Headcase) has 2.2uf/630V output caps but Stax have always used smaller caps in their amps. Their latest capacitor coupled amp (the recently discontinued SRM-300/310) used 100nf. Now I know Woo has been playing with the 2,2uf value as at least one amp had 3.3uf which is also the value used in the larger WES. I do like the Spritzer constant. It says a bit about that I just got a large shipment of Stax stuff from Japan and I had no recollection of buying some of the equipment. Still it's not bad to find a mint SR-Lambda I never knew I had...

Look what I just got, pulled SR-007 Mk1 drivers... I haven't tested them yet but odds are that they are just fine. Also got an SRM-T1 which will be converted to accept ECC99's. The damn thing looks like new too boot...

Truly, stunningly beautiful.

I have the parts sorted but haven't found the time to assemble it yet. It will probably sound horrible but well worth it for the crazy idea alone...

Yup, should only take a few minutes thanks for the ever so helpful Stax engineers who left most of the feedback loop in place. My take on this particular design is that they wanted to try something different and it simply failed. As KG said on HF, you need a lot more power going through this thing to behave without feedback and all the sims confirm it. We'll see soon enough.

ALO Rx FTMFW!!! (says a "proud" owner)

I for one don't doubt it is a good sounding amp, in fact I've been looking for a cheap one. I always liked the old hybrid model, the SRA-3S.

Well the push-pull nature of the planars should make it less important but the large diaphragms do need a lot of damping so lets just say damping factor is important.