spritzer

It's more that Mikhail was insane to use caps that big.

I'd class both the 404 and 407 as harsh though the 404 less so. The stock tubes are probably fine but it's the tube type that is unfit for the role. Not much else out there though that can replace it. The ECC99 can be fitted with some mods.

The Kimik mod is a bad joke. Take some NOS tubes (not the good ones), a tube cooler which isn't needed and then it is "properly adjusted". Now the thing about the Stax amps is that their power supplies are completely unregulated so once the line voltage changes (which it will) those adjustments are no longer accurate. The distortion you are hearing when the amp is stressed is due to the amp design simply not being to swing enough voltage. The SRM-323 is better in this regard but it sounds a bit thin. Just the nature of the beast as Stax had to build it to a price. Tubes are high voltage, low current and low output capacitance. Electrostatics are high voltage, low current and low capacitance so the perfect pair.

Two caps wired back to back in an non-polar cap. Non polars aren't all that common with the Nichicon ES being one of the few good ones left.

One of my KGSSHV transformers melted so Richard replaced it. That replacement cost me about 300$ in customs fees as it was declared as if I had just bought them... The replacements seem to work just fine but I've only done brief tests.

I usually go for no more than 35°C above ambient. That's at max load which I'd never run a transformer at.

Well I do have a contact page now... Setting up the site was easy, finding time to add anything to it is trickier. Today I started work on three new amps instead of making so product pages. I'm seriously considering adding a thread in public area here and linking to it. I'm never going to accept orders for anything, just sell what I've already built, so having a thread for it makes sense. Ohh yeah, one of the amps I started on is a KGST...

We really should do that. Please address all requests for advise to [email protected]

Any Sigma can be fixed or fitted with new drivers but not everybody is up for that.

You know you can always come to us for advise.

The specs are just fine as I have SumR units here which worked just fine with that spec. Richard just did something wrong somewhere and we are paying the price. The units I have that actually work were after I got rather cross with him... The BHSE units I was having trouble with got very warm on the Blue Hawaii so we'll see soon how they are on the KGST. The transformers I had made in Hong Kong were designed from the point of keeping max temp rise low so they run cool and very few have any noise at all. Not cheap but as if I care.

No SMD here...

Going to watch some Bottom now. Damn shame...

Just so people know this version of the amp boards has been proved working. Pretty much the same as my sets except I fixed some minor labeling issues. Power supply is a variation of the Blue Hawaii design and a slightly different version to the one I used.

Yup, they often do that. The first 313's had the PCB mounted sideways which was then changed to a normal bottom mounted layout. Ususally goes hand in hand with part changes.

The UK service center will do it no questions asked. They also reply to emails which is always a welcome thing... The port needs to be filled and the spring inside the earpads expanded in size and flattened so that the pads can be used as if on the Mk1. Then you adjust the arcs over the head, bending them into the right position for the most comfortable setting. The right amount of pressure and angle.

Best move is to use an extension. Less tug on the cable that way.

Give it time...

All of them.

Hehe....

I'll be doing something like that. I'll probably rewire the front end filaments to run on 25VDC too.

The only Stax amp to have a major change to the circuitry over the production run is the SRM-1 Mk2. There were naturally revisions as at that point in time electronic components really came of age as we moved from 10% resistors to solid 1% units. Major development in transistors too but then again the amp was in production for 12 years so things will change. As for the headphones, the SR-Omega saw some refinement of the design as they tried to address issues. The outer grill rattled so a pad was installed to dampen it. The stator support was too fragile in worst case scenarios so they tried to improve that. Same for the Mk1 007, they were trying to address issues and to make production cheaper. The faux leather on the headband turned nasty so it was replaced, the drivers were hard to install (you do it blind) so they changed that and that meant they had to alter the support frame a bit. While there are some sonic issues involved it was all done from the point of improvement. Also the 007 Mk1 was made for 9 years and most of that time they are the same. Some QC issues but shit happens. The HD650 stuff is just ludicrous as nobody bothered to check what Sennheiser was doing. Improvement by using a sturdier material than the cloth they used earlier. What I do have a problem with is Stax releasing the SZ3 version of the 007A/Mk2 without telling anybody as that's a major change. Sure it is an improvement in many ways but it totally changes the sound of the unit. Same goes for the whole HEV90 debacle, shipping out basically broken amps and then trying to deny it.

Yup, all Mk1 cables will die at some point. The problem is the strain relief or rather that it is purely there for decoration. On the SR-Omega it bends and that is also the case with the 007Mk2/009 but on the Mk1 it's just too stiff. Stax never clean drivers or attempt any repairs. They are simply replaced with what ever is in current production at the time.

I would also run the raw mains on a separate umbilical. For safety and all that something like the Neutrik Powerkon would be perfect.

The filament transformer for the CCS tubes have to be close to the amplifier board.