jwzhan

lol that's possibly the worst soldering job I've ever seen. How do you even get that much solder through?

Changed. The file is open to all for edit, so if anyone finds more error, feel free to correct it.

Here is the Google doc.

what is the point that he was trying to get through? This is the hollowest post I've ever seen in the entire year that I've been here. There are the posts that we don't give a crap about... and there is this... (and may I say that it's even posted in the wrong section...)

PMed

Anyone knows what's going on with Jeff at Glass Jar Audio? I exchanged an e-mail with him and placed an order two weeks ago, but he hasn't shipped out the package yet and has gone silent since that. I could have bought the kit from mouser, and it would have been functional by now.. I just wanted to save a little hassle and time, but it's doing precisely the opposite... Maybe I should call him on Monday...

After reversing the diode, the PSU powered up to ±30V flawlessly. I didn't use the dual track, but the negative rail and positive rail was only different by 0.01V (+30.19V and - 30.18V.) I'm not sure that dual track will make much of a difference.

return them... that's what I did when I ordered like 50 of those TO-220 mounting kits by accidents..

Very nice. I grounded the way Birgir suggested. I star grounded everything on the PSU and connected the enclosure to the PSU ground. I haven't heard any hum yet. It'll be a little messier tho, because the limited grounding positions on the PSU board... I have a few 4686s. If you need more, drop me a PM.

yep, I'm pretty sure the 1N4007 diode silkscreen is flipped. I just made a LTSpice file for the PSU, and it's giving me -0.8V for the negative rail with flipped 1N4007 diode which is consistent with what I got this morning. So if you are using v0.2 board... remember to flip it back. Also, the silkscreen for the on-board heatsink version is also flipped. No idea how I didn't spot that before....

use diode test to see if any of the transistors are blown and compare the diode test values to the one that's working. It's a pretty simple and straight forward way to find obviously blown transistors. also look for burn marks and chippings on resistors. It happens when resistors are overloaded.

don't worry about it then. 569 for bias is plenty accurate. It's much more accurate than what STAX amps have. EDIT: 9V difference off 450V is only 2% difference and 11V difference off 580V is only 1.8%. Take into account that your meter most likely has a 1% tolerance and your resistors have 1% tolerance, you really shouldn't worry about these too much, unless explosions take place.

As long as it's stable and nothing blows up, it should be fine. The difference might be caused by resistors in the ladder or the zeners not being precise.

free tapatalk today for those who haven't gotten it yet.

You really need to burn them in with a special made wood fire oven for 600 hours before you speculate anything. Also, three in a week? Is that some kind of record?

Happy Birthday!

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Very beautiful! Great build! I'm wondering if there is a source for high quality black momentary push button... I've only seen those very cheap chinese ones on chinese trade sites...

As to why that type of mounting won't work for KGSSHV, the amp boards just doesn't leave enough clearance room for the PSU, and you can't really mount the amp boards above the PSU without drilling holes on the PSU board for support stand-offs. It might work for the dynahi. The heatsinks are going to be warm though, because they are dissipating (should be) some 30+ watt of heat each at all times. You can play around with it, and maybe it will even work for the KGSSHV.. but mounting like this becomes really annoying when you have to troubleshoot the one on the bottom...

I wired two in series right after the line before the primary. One thermistor definately doesn't work with 2A and two thermistors in series is pushing it with 2A, so I figured that one thermistor with 3A is pushing it as well. Anyway, turning on the amp with only one thermistor still dims the light very noticeably while two is much better.

2A fuse works for 240V but is definately too too small for 120V. To charge the same caps, the amp draws twice the current from 120V. I think even the 3.15A fuse wouldn't survive without at least one thermister. Come to think of it... The transformer is only 2*450V@ 125mA, so it is outputting 3~4 times the rated VA at the start up.... Possibly bad for the transformer?

sometimes... shit happens...

Happy birthday Kevin!

As odd as it is.... I got one of those imbalanced Alpha pot.... the left channel is 1.5dB higher than the right. For a long time, I was using the KGSSHV with a pair of imbalanced ESP950. I knew the can had problem.. and oddly it's also the left channel that's louder... I didn't measure the dB of the ESP950 with the KOSS amp, because that broke, so I thought that the imbalance is solely due to the ESP950... Then, I got my first SR-007MK1. The left channel measured 2.5dB higher than the right. To make sure that it's the phone.. I actually swapped the output of the boards (so, the left board into right, the right board into left.) I got values showing that it's still the left that's higher, so I was sure that the phone is imbalanced; however I did not record the difference... And today, I got my second SR-007MK1... and the left channel still measures 1.5dB higher than the right... I freaked out... because either the amp has a problem or that I'm cursed with imbalanced SR-007MK1s. So I opened the amp up and did series of dB test with the pot at varies positions and changed the board output, and clearly, the pot has some problem. Luckily, I got two pots from Birgir, so swapped the other one in. Oddly, the left channel is still higher, but only by 0.3dB this time. All the differences were observed subjectively at first, then tested with a $50 PYLE dB tester. As to the the meter's accuracy, I'm pretty sure it's good enough. With the pot turned to max, the difference between the channels is 0~0.1dB with pink noise(assuming the second SR-007MK1 is balanced.) Just some additional info, 1.5dB difference is very obvious and 0.3dB difference... I don't know yet.. I haven't gotten myself out of the "left channel is louder" feeling... so I still feel that the imaging is a little to the left than I would have liked. I'll test it again tomorrow, and hopefully I'm not hallucinating with the measurements... Also, this means... that I essentialy have had problems with every part of the KGSSHV other than the Transfo.... Thank God that Richard at SumR knows what he is doing...