jwzhan

well... it doesn't really work that way... I don't really know the specific reason behind it, but the ground for the positive and negative is in different places; so even at the mirrored points, negative rail measures differently from the positive rail... The LTSpice model is fairly accurate. It's what I used as reference to fix my PSU.

I just remembered.... when I was having difficultlies with mine, my firend made a LTSpice file for the PSU, and Kevin uploaded it. It's the 500V version and is somewhere in this thread. You can poke around in the LTSpice simulator to find test points and compare that to yours. Also, what I was describing above is a temporary short to the ground. It happens about 5~10 seconds after the startup. The caps get fully charged and instantaneously dump everything into the ground.

Short under the big caps won't be a buzz. It's more like a BOOM! with very bright flash and burn mark around the cap.. I'm going to guess that something else is causing the problem.

Also, for the KGSSHV are you planning on a two case design? because you can't mount the 10m90s like that with the 3U case. Digital attenuator doesn't cost that much more compared to what you've already spent... about additional $200. I would go that route. Should provide superior sound and much more refined attenuation. Your progress is much faster than mine.... I haven't touched mine for a month... I've just been enjoying the KGSSHV...Ay, I really need to get off my lazy butt and get going. Edit: to just posted: You probably can't get the KG attenuator anymore... because there was only one run and that was long ago.. I haven't seen a populated or unpopulated board go up for sale for a long time. However, the AMB R-2R digital attenuator uses the exact same chipset and same voltage as the KG attenuator. This only difference is the Relay voltage. You can also use their LCDuino controller. I'm sure you can fit it in there.

@eggil I don't think it matters, because looking at the photo I took, the tapped holes for the brackets are symmetrical for the dissipante series (no idea what the slots are for.) But I'm not sure if it's true with other cases. (I think they have the exact same face plate for all their pesante cases with or without heatsinks, thus the multiple and useless holes. For example, only 4 holes are used to secure the heatsinks in the dissipante cases and almost half of the pre-drilled holes are covered up by the heatsinks, including those slots...) @deadlylover I'll PM you later about the specific numbers.

That's enough to convince me that they are genuine. I'm definately in for 4686, 1968, 216/79 and 213/76. I might have to decrease the number of 4686s to get more others if that's possible.

Indeed they have very good price on everything. I cross checked with BDent and Satodenki's price is almost always half of BDent's. I'm definately intereseted in some 2SA1968LS @315yen/pcs; 2SK216&2SJ79 @600yen/pair; and 2SK213&2SJ76 @500yen/pair. (I'm pretty sure many others will be interested at those prices.) The prices are almost too good to be true.... so I have to ask... how can you be so sure that they are genuine?

Whichever works better for you. Just let us know the final price. IMO 185yen is still a very good price.

I'm not that into writing instruments, but I happen to have a Mont Blanc Boheme fountain pen and a Mont Blanc Starwalker Rollerball/Fineliner pen. They are gifts from my parents. I find weight distribution more important than anything else, and Mont Blanc does it very well. I never felt the need to press down for the ink to flow smoothly and never had sore hands after hours of note taking (unlike when writing those awful generic pens..) I haven't tried Lamy's or Pelikan's pens, so maybe they work just as well at a fraction of the price? As for pencil, I'm still using those yellow wooden ones.

Pretty good price compared to those ebay ones that may be fake. I'll be in for at least 70 pieces.

I just had the most ridiculous conversation with a guy who PMed me to sell me his 007MK1s on the other forum. I'm just going to go ahead state the gist and quote some of the highlights and you should get the idea. He PMed me to tell me that he has a Belted 007MK1 that he didn't need to sell but will go ahead and sell to me because he just happens to see my classified ( Da Faq?) I went ahead and ask him what belted is... and here is what he said... "Belting Is audiophile processes in which the natural vibrations of the materials which derogate the hearing are silenced. It is explained on Peter Belts site in England. called PWB Audio." He also said that he lives on the old personal property of North America Stax in Signal Hill in Long Beach, CA... and hinted me to drive up there to try the phones.. (I didn't try to confirm what he said, because I had no interest in those Belted 007MK1s.) So I went onto the PWB site... and saw some putting blue papers under equipment will dramatically improve performance and deep freezing your CDs for superior sound quality... (really?) After that... I politely replied him that I'm not interested in meeting in person because I can clearly see that we have very different beliefs in audio. Then, I think he got a little angry over my response.... "I do not understand that it was a belief. It is the science of sound. You were very close to hearing sound that is so unbelievable that it goes straight to you soul. At this point you are displaying the worldlyness of a member of the KKK.... I guess God is out of the realm for you also. I am a avid believer in PWB and God and Accoustic Revive and Schumann Frequency Generators and anything that helps make my grip sound more live. I have experienced the difference in both. Have you?Please do not take offense but May God Bless. You were so close to a beautiful journey because once the door is open the light is very wonderful." !!!!!! and there are more.. "Thirty five years ago when we put on concerts in the Black Hills of South Dakota and Billings Montana everyone heard sounds that could not be achieved in a hall in a big city concert hall. Dave Mathews has expressed this about the Gorge. Just for you I will tell these people they do not know dick." which really sounds like an excerpt from the book Lame Deer, Seeker of Vision I think I will just end the conversation here..... it's getting too weird...

I really wouldn't hope for the best in your situation... I had one channel that was doing similar things (after some initial damage by accident,) but I didn't try if it were able to produce sound after the damage. I reaplaced the blown resistors, powered on without any problem, and it ran some 4 hours before I turned it off. Meanwhile, I tested the current draw across the damaged resistors against the other working board, and the resistors that were damaged (replaced) were drawing some 30%~40% more current (forgot the specific values.) I also wasn't able to get the offset to 0V with the default resistor values. Right now, I threw that damaged board out because I couldn't identify the cause... and the newly populated board is running flawlessly. (left on for some 10 days during the longest run.) Good luck on the build, but just as back up, I would get some spare boards and parts just in case if you decide to toss the current one out. By the way... trying to fix the damaged board wasted almost a week of my time while populating the new board only took me one afternoon.... a much easier and quicker fix.

ay, I guess I'll just have to return this and get another pair then.

I just got my 007mk1, but it has a slight channel imbalance issue. The left channel is 1dBA higher than the right. I realized it immediately when I put them on, then I confirmed it with a dB meter. The seller, of course, claimed it to be free of such problem. He had a 717 amp, and probably didn't notice the imbalance because it is so small. I just want to know if this is a common problem, and if it is a problem to be concerned about. Thanks.

Last time I went to an USPS, they actually ran out of the international mail declaration forms and I had to go to another USPS. How the F do you run out of those.. it's ridiculous. And yeah the price, a small bubble padded envelope used to cost $4 and now it costs $6. Priority used to be alot cheaper than express if you can fit the thing into their boxes. Now they are almost the same regardless the box used. Air mail doesn't have tracking or insurance (impossible to add) as far as I know, which is why it's cheap.

more than enough. Thanks Kevin.

black out is to prevent arcing via the cap metal casing.. more relevant to HV... Kevin, is it possible for you enlarge the holes for 2pF and 0.47uF (on the amp board) a little? I just got some 0.47uF wima caps, and again the leads don't fit... I didn't want to look for replacement, so I'm just shaving the leads to make them fit... Lead diameter for the wima is 0.8mm

Well, it seems like I'm the only person to experience it so far. Might very well be caused by placing the cap too close to the board, since I had no knowledge on what high voltage is capable of, when I started the build.

yay, no more ground planes under caps. Thanks Kevin. And just out of curiosity, is there any particluar reason benefit to have one 2K and 24V diode per power transistor? There was only one set per rail in the v0.6.

DCA75 PRO definately looks interesting and much more capable than the DY294. It can test MOSFETs, JFETs and some simple curve tracing, which the DY294 can't do. However, what's with the minigrabber thing, especially because they are simply soldered onto the board with no strain relief at all... EDIT: I guess minigrabbers are easier to use for testing two in one or canned packages.

You will be amazed by the number of people who think Rudi is a genuis in Asian forums. And frankly if anyone says otherwise, he will simply be flamed or silenced. The funny thing is.... almost no one has listened to the shoddily made amp or see the measurements themselves.. They reasoned that Rudi amps are expensive and people who buy them are not braindead.. (or are they?) enough said... I'm glad I don't see Rudi in any of the English forums that I visit now.. I guess I owe my thanks to Birgir and Kevin.. I think I will stick with the default gain with HV for now, but I'm still interested in knowing how to lower it.

That's would be KG attenuator with LCDuino controller. I emailed Ti Kan on the matter for confirmation and that was his response. There is a super-cap on board that keeps things remebered (not only volume position, but also other settings such as time and input selection if you also have that board,) but only for a certain amount of time. Similar to how the motherboard remembers the BIOS setting. If the cap runs out of juice, the settings will be cleared out. Anyway, by leaving the attenuator powered on 24/7 and keep the wires short, it can also double as a separate volume control with the main amp and its PSU off... When I finish mine, I will probably put it in between KGSSHV and 1600HD and just turn the Alpha pot to max. The Alpha pot is not really giving me much control over the KGSSHV's volume.... I've never turned the pot pass 20 degree... it just gets way too loud hmm.. I thought the DC offset servo is a part of the feedback... I guess I was wrong all along. Thanks for the info.

I'm just curious. Do you have any photo of the build? From what you said earlier, does the opamp feedback circuit do nothing at all? Might be fake parts if it's happening to both channels. Did you buy spares for all parts? I would test them. For the BOM, I've fixed most the the problem, including opamp sockets and the 2pF cap. EDIT: Birgir beat me to it.. yeah.. I was also thinking of the same thing.. I wouldn't even bother with stripping the board though, because the passive components are cheap anyway.. Start anew with new boards is the best way, because it definately is easier... Hopefully you bought enough spares.

same here. When I placed a $600 order last month, they only shipped it out on the third day. I thought it might be because the order contained too many items, but last week when I placed an order with only 15 items, it still took them as long... I also ordered some parts from digikey on the same day last week and I got the package on Monday, while Mouser's shipment just arrived yesterday (Thur.) Not sure what's going on.

I just found thirteen 2sc4686A that I thought I lost due to misplacement... Made me a very happy man... Pure Silicon Gold.