spritzer

That would be a good idea. Having 50 useless boards does sting a bit...

They could be hid next to the output devices but since the original article doesn't have them I think you are right. Justin's version didn't have them either As for the sound, it does depend on what output device is used.

There is no mod for the 323S unless you count buying a 727 instead. Raising the voltage would involve higher rail voltages so pretty much everything new...

Stunning work Kerry. Q1 and Q5 are silly small so congrats on being able to hand solder them.

I have KuboTen order them from Ippinkan. Stax refused to sell me some 009 pads though claiming they aren't user replaceable. "That's not a flaw, it's a feature...." The tubes starting to conduct would be my guess which is why output relays would be a good idea. We've wanted somebody in China to make a KGSS for years so that is all good. Some recognition would be nice but mostly so people know what they are buying. The price is certainly attractive and the build quality seems good enough: Cheap pot but at just over 700$ shipped to the US it isn't all that bad. The one I bought shipped yesterday so we'll soon know what Kevin thinks.

Well naturally since somebody could possibly have dissed that piece of shit 45 amp that he's peddling for Eddie Current. You know the one that screams at you when you power it on. Pure quality there... One aspect of that whole discussion is the ludicrous concept of how Stax "voice" the headphones. It's quite clear that Stax have just one goal when designing transducers and that's to make them better, something which doesn't always work out. Ever since day one in 1959 it's been about getting better diaphragms which then in turn means the structure is the issue which then needs to be redone and then the cycle repeats. There have been a few exceptions from this rule such as the SR-Omega but that in turn lead to the 007 which ticked both boxes so not a whole lot of difference. Then the 007 SZ2 which fixed some issues for a better product but generated a whole lot of other problems which the SZ3 set out to fix. Then they dropped in the new diaphragm which made everything even worse... In terms of amp design this could be compared to increasing feedback, it will yield some better specs but over all you are getting something that sounds progressively worse. Not magic to this, it's just that THD is pretty meaningless as the sole basis of amp design. I also know full well that Stax believe each new version is an improvement and in some aspects they are, but some do miss the point a bit. The LNS was a bit too mellow for some people so the SR-404 spiced things up a bit which didn't work too well. They also introduced new earpads then which didn't work all that well either.

Indeed so here is something Stax related. This one has been discussed before: http://item.taobao.com/item.htm?id=36525626565 Well I did some digging and found some pretty poor internal pics but I'm 99% sure that this is indeed a KGSS. Certainly uses Kevin's BH power supply and the layout matches so we've naturally ordered one... I'm sure we can find a far more elegant solution to that. *Goes off to design a low pass filter for Stax*... Since you have a KGSSHV now, does it make you want to rip out your ears with the 009? I'm a year older than you so clearly half deaf by now...

For Dale resistors there are always the CCF60 type which have color bands on them for easy identification. 500V spec too which is nice. Nahh, better ask away so things can be fixed. Fucking up is just part of the process

That would do it.

Couldn't have said it better. He also thinks the HV is bad with the 009's, he should try that SRM-323S... I also love his response about age. Sure, being younger will often lead to better hearing but experience is the key here. Well that and not being an idiot.

There are 4 zeners for the bias supply, 3*150V and one 130V. That would work but I highly recommend doing a proto run on any untested pcb.

So they want people to use two amps with non stepped volume controls? Wow... that is pretty much priceless. Wait no it isn't, it would cost 3k€...

Just so you know, there are no good offboard versions available. The ones I use in my tiny amp require some care or the amp will blow up (i.e. everything was sacrificed for space or rather lack there of) and the new slightly larger units aren't ready. Too busy building to work on them.

Indeed!! I just looked up this amp and I love how it is supposed to be balanced but there is nothing balanced anywhere. Well unless that 3 pin XLR balanced output is the new fancy version of balanced... with shared ground.

I take it that this is the new king of the fucktards? The amps are clearly to blame here when the headphones have a rather enthusiastic top end. Better stick it on the 727 with very little HF presence and a sound warm enough to shame most SET's. Sure... sounds like a plan. I do wonder if the GES is part of this? Does mean we have to make our own 009 design, cobble something together that barely works and claim it has great synergy....

I really liked the last one...

The caps were shot so replacing them helped. Didn't cure the ever present hum though...

The stock amp didn't have zero offset either. I would have to dig through my email archive for the exact figures but it got a lot better once I redid the PSU

Not much of use there for us. The voltage divider is fixed so drive it off a regulated PSU for a regulated normal bias.

That would qualify as massive

The Antek units I've tried have all been excellent. Something like that 400VA unit is gigantic though...

So a couple of things. First, see this: Looks just like all the KGSSHV's I've built but this one is different. Aside from the 2SK170 input fets it's all in current production. It runs at +/-400V but with just over 8mA of current and uses Fairchild FJPF2145 output devices. Sounds pretty much indistinguishable from a +/-500V version I built as well that is pretty much identical save for the output devices and voltage. Now a couple of neat points about doing the amp this way, first of all the parts are all easy to source and secondly, so are the transformers. Edcor has a nice dual 335V winding unit in their catalog so add a small 30VCT/25VA unit and you are set. No need for anything custom and the PSU mods are dead simple. Just change the zener string and the divider and bypass the voltage divider that feeds the bias supply. The second point is that I've finally given up on thePMBFJ620 fet. Nothing wrong with it except it is just so bloody tiny that it's all but impossible to solder. They will be removed from future versions of the boards and might be replaced with the SMD LSK389.

You'd have to be quick as the chassis for those two amps are already on their way to me. All the boards are ready and have been for months so it's just a matter of doing the chassis stuff. I have so many half finished projects like this that need to be finalized. Way too bloody many...

I have enough parts to build two more KGSS units so they are on my todo list.

Happy Birthday!!