July 15, 201411 yr Thank you for the quick response, this is interesting; would they put a 1 before the 4 rather than 0004?
July 15, 201411 yr Since I'm in Tokyo at the moment I called STAX and asked about the 1004 serial number and the person there told me that the serial numbers are generated randomly and do not represent the order in which they were made. I asked about the number over 1000, and he said it's possible. If so, there might be others over 1000. I've seen about 10 of these and never one over 1000, but maybe there are more, unless the serial number is inaccurate.
July 15, 201411 yr i think they do start at 1000. why, i dont know, maybe to make it look more popular. and in the case of the SR-009 the serial #s are definitely consecutive. all other stax products i receive have higher serial #s than the previous order (and i'm surprised by how many of the amps they make -- probably almost all for Japan) Edited July 15, 201411 yr by justin
July 15, 201411 yr The modified Chinese KGSS is superior to the current stax amps like SRM-727/007TII, but you need to rewire the input section and the pot must be replaced. Also you must do some small changes like thicker cables for the voltage input section and its better to take a new a case for the bigger pot and better cooling. The Woo Audio GES is a good amp for the SR-407 and in my ears a better choice then the current Stax amps but not on the level of the KGSS. I prefer only the SR-407 in the new lambda series, but the older Lambdas like Signature, Nova Signature are even better. Hi Nomenec, Interesting post. Do you have pictures of your modded amp? Spritzer doesn't Like the 407, but what do you think of it in comparison with the 207? I have heard the 407 and it sounded OK to me, but I am no expert.
July 15, 201411 yr 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.
July 16, 201411 yr 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. Given all the effort to fix it up is the "cheap" asking price for it still worth buying?
July 16, 201411 yr Hi Nomenec, Interesting post. Do you have pictures of your modded amp? Spritzer doesn't Like the 407, but what do you think of it in comparison with the 207? I have heard the 407 and it sounded OK to me, but I am no expert. http://www.open-end-music.de/vb3/attachment.php?attachmentid=8856&d=1404570749 http://www.open-end-music.de/vb3/attachment.php?attachmentid=8858&d=1404571198 My opinion is i like of the new series the SR-407 more than the SR-207 and find the SR-507 horrible, but in the end the older lambda models are even better.
July 16, 201411 yr http://www.open-end-music.de/vb3/attachment.php?attachmentid=8856&d=1404570749http://www.open-end-music.de/vb3/attachment.php?attachmentid=8858&d=1404571198 My opinion is i like of the new series the SR-407 more than the SR-207 and find the SR-507 horrible, but in the end the older lambda models are even better.Thanks for your reply. The amp looks great in the new case. What is the white block at the bottom? What did you changed at the input?
July 16, 201411 yr Given all the effort to fix it up is the "cheap" asking price for it still worth buying? 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.
July 16, 201411 yr Given all the effort to fix it up is the "cheap" asking price for it still worth buying? 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...
July 17, 201411 yr Truly. I briefly entertained the idea of buying one of those, but it seems like it might be simpler to just make one from the start.
July 17, 201411 yr 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.
July 17, 201411 yr Truly. I briefly entertained the idea of buying one of those, but it seems like it might be simpler to just make one from the start. Same here, doesn't really seem worth the effort now. //UFN
July 17, 201411 yr Same here, doesn't really seem worth the effort now. //UFN Ditto. That thing sure is a clusterfuck.
July 17, 201411 yr If the amp was $400-500 it would've been worth the hassle for me at least, but the $700+ meh.
July 18, 201411 yr 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. Hello spritzer, Its better to rewire it or take a new case. I have done the following things: 1. changed the 8 resitors for the two channels R73/74/75/76 and R35/36/38/39 to 100K. 2. thermal paste on the heatsinks for the transitors 3. removing resitors R9-R12 (2,2K) and rewire the input section with a new 27K Alps pot 4. new case with complete rewiring of the voltage input and grounding, new power button with relais Any other useful hints, i have a newer PCB F1a-1413? http://www.pic-upload.de/view-23329932/innen.jpg.html RCA/XLR switch has only a function for XLR mode, both together are not possible but thats not a big problem for me i use only one source. Its a lot of work, but the chinese KGSS sounds now after the modification very good with black background and no issues.
July 18, 201411 yr No need to change the chassis as it works just fine. I needed to properly mount the transformer and replace the feet but that is minor. I also had to tart it up a bit... It's nice to have power knob that actually tells me whether it is on or not. The input section is so fucked it's beyond belief. So the knob is wired the wrong way, the switch doesn't work and the RCA's are actually hooked up to the - input so any attempts to fix it means you have to start scratch. So just cut a bunch of traces and jumper. Here is my board as it is now: I changed the feedback resistors to 100K and the pull down resistors for the last stage changed to 350K RN60D's as they are run on the limit. The stock RN60D resistors changed to the correct values (300K and 150K respectively) and 2W Koa SPR. I also changed the resistors which ground the RCA/XLR switch to zero ohm jumpers.
July 18, 201411 yr So do I understand correctly that you ordered this Chinese made amp, and it wasn't even close to working when you got it? Or was this a fixer upper from the start? It's just unreal how much is wrong here.
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