insanity

I just noticed that the two .47uf/50V disc caps don't seem to have the same lead spacing.

Looks good. I guess I'm not the only one wanting to build this. Just out of curiosity. What is the reason why we use 4 separate rectifier diodes instead of one bridge as in the kgst supply?

one board may have to advantage of less cables, if possible to modify accordingly. but i think for shipping and practicality reasons 2 boards are probably better

That's looking impressively small. A depth of 4.35 inches implies a horizontal mounting unless on goes for at least a 3U case. But horizonal is probably the easier and better way anyway. I like it very much. Does it make sence to use mpsa06 and pzta06 on the same board? May I also suggest to add descriptions for the trim pots on the silk screen? Makes it easier..

Not the Carbon?

I would be in for 1 set for sure!

Probably doesn't make too much sense going to onboard heatsinks the size of the 727... Any idea when the boards will reach a stage suitable for a board run? Btw: What version are you using for your carbon builds birgir? Which amp board? Which servo? which Psu?

This heatsink would be compatible with a to-247. But 9w is too much.

From a thermal and technical point of view, would it be possible to make kgsic boards with onboard heatsinks such as this? FA-T220-64E

The problem has been solved by replacing the two 100ohm resistors and the 6.8k inbetween. Looks like they may have shorted to ground. Replaced them and mounted them a bit elevated. The smoke took one mpsw56 with it, which has replaced too. Seems to work fine again. No more sizzling...

Omg now r35 or r37 (100ohms) started smoking... This doesn't look good.

I swapped the boards and the problem persists on the same board. I also changed the 1n914 diodes after the lsk389 and the 500k input resistors. No change. Any other ideas where to look? Slowly I am starting to think that this problem has been there all the time since I built the amp, but I have only noticed it when I started turning up the volume a bit, because of my new 007s (which was not necessary on the 009). I initally built the amp with all ixys parts and a few month ago I switched to 4686. Only the current source is still ixys. Unfortunately I cannot tell (as mentioned before) if the problem was already there with the all ixys build. If you recommend replacing the remaining transistors (on the heatsink) I guess I would start with the remaining ixys pair...

Ok Jim that sounded plausible. Here is what I did. I stepwise replaced all the transistors that are not mounted on heatsinks, but the problem has not changed. Could a resistor be causing the problem? Or maybe on of the diodes? I cannot imagine how a problem with the 3rd and 4th stage could be so dependent on the volume control/grounding of the inputs. I am confused. Help?

Ok I did the following test. When I removed the input wires from both boards, without grounding the inputs, the sizzling channel started sizzling well noticeable, whereas the other channel remained almost silent. Interestingly, when I grounded the inputs from the sizzling channel it was almost quiet, with the sizzling being barely noticeable to unnoticeable. This seems to rule out the elma as a source of the problem. Does this sound more like a problem of the first amplifier stage or another stage? What parts would you start working at? lsk389 and mpsw06? below it? I don't have a scope...

I have watched the problem I described below and it still persists. Does anyone have an idea what I could check or replace? Since the volume of the sizzling I hear only through the headphones is dependent on the volume set on the elma stepper I am confused where it could originate? Does it make sence to assume it is not coming from the amp board, but from the elma stepper or so?

Yes I hear it only through the headphones. Touching the case has no effect. My XLR input jacks are both directly connected to the chassis. Chassis is connected to earth. The amp boards are connected to ground through the psu board. I just turned on the amp again and this time the problem did not appear (the amp was off for 1h). hmmm. I guess I will watch it and report back.

The first thing I did was checking balance and offset. Both were good. I will try my best to describe what I hear. Its a noise similar to what you hear, when you push the headphone cups against the head but less loud/less pronounced. It is not continous, more like there one second, gone the other. The volume of the sound becomes louder when I turn the stepper to increase the volume.

I have removed the amp board and visually checked it. Also used the opportunity to add 100ohm input resistors. The problem still persists. The sizzling changes in volume when I turn the volume pot. If the sizzling originated from some arcing, changing the volume should not have and impact? yes? There is no audible physical noise coming from the amp.

I recently noticed a strange behaviour of my good old KGSSHV which has probably been there from the beginning, but has gone unnoticed with the 009. Now I have the 007 and I had to turn up the volume a few clicks (elma stepper). I now also notice it with the 009, because I now what to listen for. During the warmup phase, one channel presents a sizzling noise which is clearly noticeable but not loud. After the amp has been running for some time, it dissappears. Does anyone have an idea?

I want to build a Carbon so badly...

Very interesting. Why did you use ceramic insulators under the SICs? Aren't they in an insulated package?

very nice and small!! is it your first listen to the kgst?

Very interesting for me to read. Thank you!

Nice experimental looking build. How does it sound?

I am interested in a set too. thx