spritzer

If this was built with some sense then it would be a nice little amp but there is just so much wrong with the input section. I set to work on the RCA/XLR switch and found this: That would be the earth contact to the chassis, simply soldered to the steel screw. Fell apart when I simply pulled off the back panel so it has been done properly now. Also removed the stock feet (the chassis wobbled) and found out why. Nobody had thought to clean the mounting holes so they weren't flat. Discared the stock feet and put in some nice aluminum units instead. I have to open it again to find one trace on the input that is fucking it up for me.

To further add to this, I couldn't resist temptation and tore into it. It's very Cavalli in many ways, not really meant to be dissembled but at least semi decent soldering. Also something it has in common with Cavalli: Thermal paste is overrated anyway... So I ripped out all the underrated resistors and the volume control. The volume was an even bigger clusterfuck than anticipated, it was quite simply all incorrect. Channels are reversed, RCA switch doesn't work and naturally the input goes in the center for some unknown reason. I set to work... It took some doing but the TKD 4CP-601 managed to slot in there. Underneath all the traces are cut and replaced with wires but I was too lazy to fix the RCA's and the switch. Channel reversal is easy to fix too by simply crossing the outputs. So here is what it looks like now: So the feedback is fixed, the current source resistors for the third stage are the correct value and wattage, same for the pulldown resistors for it and the fourth stage. Sounds much better now and the volume can actually be used...

There is some value in there but also a lot of problems. How that balances out is a personal thing but this one will never be a full blown KGSS. Current is too low for that and no good way of changing it, at least not in the stock chassis.

The Megahertz stuff is a bad joke...

Just got the Chinese KGSS and the first job was to properly secure the transformer. The rest will need an awful lot of work. The volume control and the entire input section is fucked. Output stage has to be restored to proper working order, all transistors have to be remounted, all standoffs replaced with metal ones, output resistors fitted and all parts being run on the limit changed to properly rated units.

I had 0007 or something like that so they certainly started at 0001.

I could use that HE90 box to make mine complete but hell no at that price.

The audio grade transformers are already shielded so not a whole lot of benefits to be gained from the can. Looks real to me.

Just so it is clear, this PSU is exactly the same as the other one I did. Kevin just wanted to move it to the same layout architecture we use for all other boards so we drew it. Ohh and everything changes for us. There is nothing set in stone so constant improvements. I've lost count of how many revisions there are of the KGSSHV boards, at least 60 minor ones and almost 20 major ones.

It's quite cramped, that's how. Here is the latest version: Only major change is the voltage selector PCB which makes the AC wiring all neat and tidy. Nearly every centimeter is used now and I'm up to 9 pcb's per amp. The bigger changes are outside as I changed the layout a bit from the one above: It's very hard to photograph the chassis as it's so reflective... Thanks for the offer but I do have a Wordpress site up and running but it appears to be down now. My friend hosts it and he's been having some issues due to some of the other stuff being hosted there. It's mjolnir-audio.com and .net when ever it is up again. Haven't done a whole lot with it yet but I need to add all the DIY stuff and what stuff I have in stock.

http://www.pricejapan.com/front/e_good_info.php?code=996&category=10 That makes the amp practically free...

The 207 is still a bit on the bright side but nothing like the 307/407/507 so it's the one I'd pick. They are easy to find on ebay as a part of the SRS-2170 system. The small Stax amp included isn't the best but it's quite good for the price. All the systems on ebay are 100V but it uses as normal 12V/1000mA adapter but with the polarity reversed. It's easy to find a 230V unit and simply reverse the output plug to fit the Stax amp. 323S plus the 207 would be my choice but the Chinese KGSS will be better once it it fixed. I'll start a new thread when the KGSS gets here and I start to rip it apart.

The GES would only be a good match to the 407 as the 407 is pretty much horrid. Even the 207 is better let alone the older Stax models. The GES is a fine amp if you can get an old one cheap but I wouldn't buy new. The Chinese KGSS will need major work before it will work properly. Some components are run right on the limit while the volume control simply needs to be replaced. My amp has hit customs so you can expect some pics on how to fix it next week. The 006t isn't my favorite amp so perhaps try the 323S and the 727. The 727 is pretty bad in stock configuration but once modified it is quite nice.

This really isn't your typical tube amp, that's for sure. The tubes are used in the same way as you'd use a transistor. Just as a heads up, prototype boards for the KGDT have been ordered so things are moving forward there as well.

That's a lot of S's....

That would be nice if the bloody thing would fit in the chassis. Well they have a minimum order of 800$ so you cant' just buy one or two. Shipping is on the astronomical scale and the transformers are cheaper but not a whole lot so when you set them strict requirements.

The cathode sits at -400V which is well above the heater to cathode limit. Most "normal tube amps " (as in designs as old as the hills) have grounded cathodes so this is less of an issue.

No tubes and nothing is set in stone as of yet except that it won't have tubes. We can call it a mix between the KGSSHV and the KGST.

If you want to run it at +/-400V then you need 325-335VAC rails. 280VAC for +/-350V. For current 110mA is sufficient but I'd shoot for 140-150mA to be on the safe side. 30-36VCT is about 500mA. Heater windings should not be CT as they have -400VDC floating on them. You have to have two heaters or you will have massive problems so one for each board. 1.5A is more than enough to account for the variables in the tubes. No soft start for me as I simply don't think it is needed. The tube won't arc at these low voltages.

I've had two SumR self destruct and it ain't pretty. Speaking of transformers, seems Keen Ocean didn't quite get my requirements. The one in the middle should be about the same size as the ones on the left... KGST transformer on the far right, each weighs a whopping 3.3KG...

Are you running 10M90's at 500V in the KGST? That's not the best of plans...

The plus side is also how cheap it is to build and everything is in current production. No SMD parts either as the voltage is low enough to use KSA1156's and Antek transformers will work perfectly. A pair of ECC99's is about 35$, 12BH7's less than that and 6N6pi's way less than that. I also bought some parts to try a KGST with current made tubes.

It's also hard to be negative about anything if you lack the basic brain activity to understand any of this. I think it is the true mark of stupidity. It doesn't even work in Icelandic where word order is pretty much free.

The real problem are the tubes as not many can handle more than 300V. Push them hard and it all falls apart... The only dual I can think of that is rated for 500V is the 6CM7 but it's a dissimilar triode so not suitable for something like this. That said some of the computer tubes and TV tubes were meant to handle 600V peaks (or even higher) so they might fair well. The amp features switchable heaters on the board for 6.3V so either pin4 and 5 or pin4+5 and 9 for the 12V units. It also has switchable CCS so the current can be lowered with a jumper for tubes that can handle less power. Right now the list of tubes this one can use is : ECC99, 12BH7, 6N6pi, 6CG7/6FQ7, E182CC, 6840, 6350 and 5687. Should be more out there...