spritzer

Nope, except our mantra of MOAR!!!! I've been on a bit of a counter swing to that today as I was doing some inventory and realized I had way too much crap. Assembling and testing Stax headphones from parts can be fun... until one doesn't work as it should.

Ahh that makes sense, cut corners where the damage can be huge. Gotta love government thinking...

Yup that's it. A couple of drivers that most people would have thrown out fitted to the most expensive frame money can't buy. The 404LE is a bit more refined but the tone is similar. The 323S is the better amp than the 252S but the small one is damn good for something so tiny. The major limitations don't show up until you start to push it. Same headband used on both though the head pad is different. The earpads on the 207 are roughly the same thickness but vinyl so not as nice. The 207 is also a bit lighter given the less substantial cable.

Glad to hear you are all safe as this has been followed closely here. I baked some "landmine" cookies in your honor though...

The SR-404 is identical and the SR-SC1 and SR-404LE are all similar sounding, though the latter are quite a bit superior.

I'd stay away from the SRM-600 given the very high failure rate. It's always the plate resistors that die so they could just be replaced but that's pretty much the amount of work needed to change a T1/006t to use ECC99's so hardly worth the price difference. The Koss isn't a bad choice. Simply upgrading the wall wart for the E/90 amp won't make a dramatic difference so your best bet is always a Stax amp. Even cheaper is the Stax SRS-2170 which is pretty much untouchable at that price. Sounds far better than the 307 too and the Japanese units are easy to use with a domestic 12VDC psu modified for the correct pinout. Any of the Lambda Nova units would also be a good choice but many of them aren't aging all that well. The adhesive used is acting up and the pleather parts are flaking or even worse. Some of my favorite headphones ever though and my main set these days is pretty much a Nova Signature.

Here is the problem, which type of Philips is that? There are two main types and some other less well known versions. That's why we like those boxes full of assorted bits...

The SRM-1 Mk2 has only 4 output devices so the current sources are resistors. Even on the SRA-14S (released 3 years later) this was still the case (though the circuit is far more complicated as a whole) and it wasn't until the SRM-X that they moved to transistors. They did progressively turn down the bias current though so the amps run cooler.

All the Stax amps have used Jfet inputs since the early 70's. The 313 used the J109 dual fet until it was discontinued and replaced with matched pairs of J74's (which is just what a J109 was, matched J74's) thermally coupled.

There are at least two main versions, the one with the normal bias and the one that is Pro bias only. Both have the side mounted PCB but there were some small changes to the chassis such as went holes on the back. There are also some that look a lot like the 323 inside (pcb sitting on the bottom of the chassis) but I've never seen one up close to know if it's really a 323 in an old style chassis or just the first redesign to get around the discontinued dual jfets at the time. This is Stax though so there could be other revisions that nobody knows about. The SR-2 above doesn't exist officially yet, there is one.

That's pretty much as rare as they come. There is nothing there but a fire hazard. The person doing that has zero clue as can be seen from the axial power caps haphazardly mounted or the local PSU film bypass caps in the amp stage replaced with some audiophile crap.

Did you export the edge?

We need to melt down that silver into something useful..

Here something funny, an upgrade service for Stax tube amps... T1 and variants 007t and variants Not so sure about this clusterfuck...

All of the ground connections are shared so anywhere with GND next to it.

The quad ALPS layout we used on the Megatron works perfectly as a reference.

I've always been meaning to buy a pound or so of 925 sterling silver wire to make some cables. You know me... I buy in bulk!!! We so have to cryo some headphones one of these days. Take a SR-009 down to 4.2K and see if it changes anything. I do wonder how peek will behave after doing that... A specific thread about ripping shit apart and analyzing it would be fun. Cables are extra fun too as it is all BS. Virtual Dynamics was my favorite, garden hose filled with ferrite powder and bog standard inwall wiring (solid core).

The amps do need to be adjusted when swapping tubes but it's pretty easy to do. The adjustment pots are pretty much the hardest part as they are touchy and can break apart. On the last T1 I bought back to life both the offset pots split in two when I tried to adjust them.

The HD580/600 cables are a pain to work on so I'd use a 650 cable. I do like Ari's idea though.

At least they used an Amphenol plug for that cable... Speaking of connectors, I wouldn't use a RJ45 as the conductors are tiny. What about neutricon? http://eu.mouser.com/ProductDetail/Neutrik/OSC8M/?qs=sGAEpiMZZMsBYeZNO4kNBLFlOQUkTYt3

You have it rough my friend. I really should finish the KSA-5 one of these days but 3 complete sets of KGSSHVk boards need to be tested...

You could also just hack off the ends of a HD650 cable.

As Kevin said, while this may look easy enough the parts are a pain to work with. The traces lift off the PCB if you just look at them the wrong way and to make matters worse, the PSU caps aren't proper snap in units but have longer leads. These are bent into place and then flooded in solder so they can be a pain to replace with modern units.

Ain't it grand? There have been some issues here too and they have consumed a lot of my spare time. Simply getting replacement transformers from SumR out of customs was all but impossible and took a month. Ended up paying 150$ in tax for free replacements. Goes to show how stupid the HF lot is to think I do any of this for the money. If I'd ever sell an amp that I broke even on then I'd take it as the first sign of Ragnarök!!! That said, two more HV's under way. There is an output device in current production that might work at +/-450V so that needs to be tested. The Vbr fits but there is no better test than to build a channel or two. The HV's nature to go all arcy sparcy and issues with finding good sand is pushing me to try a +/-400V version. At that level it is no problem to source output devices in current production making things a whole lot easier. We can also increase the current which is always good....

Have a good one Dinny!!!