insanity

Could you elaborate a bit on the special 009 amp in planning? I am very curious about it.

This is normal, if you do not use a high impedance voltmeter. Thats what the TP is for.

I am finished!! Check out my post here:

I was thinking of the offboard version. I did't know there was an offboard version that incorporated that already.

That is unfortunate. Will future KGSSHV board therefore feature an (isolated?) alternative for the A1968?

So if you can get this new part, will you start selling it and the A1968?

This makes sense to me. But what about parts like A1968? Doesn't seem easy to source aswell. Since I built my KGSSHV with the 1n100D: Why did you move away from it? Too high capacitance? Too much drift?

Wonderful work spritzer. I cannot stop staring at this picture. So many boards!!

Take the stth512fp which is the isolated version. do not use non-isolated diodes. the stth512fb is a spelling error and does not exist.

Yes it works.

I just replaced both devices. I don't know which one of them was the culprit. Maybe the lsk389 is fine.

Looks like my nose (with a bit unexperienced brain) was right. Replaced the lsk389 and the adjacent mpsw06 and the problem is seems solved.

after moving everything around a bit, the hum is still there. I noticed that even when I ground the inputs via 250ohm resistors, the hum shortly returned during the described turn off phase. I even switched the position of the two boards and the hum goes with the board. I think that makes a grounding issue very unlikely. Furthermore the "hum" sounds a bit rougher than the classical 50hz hum we get to hear in grounding issues. Is there any particular device you would start on checking/replacing? Rather inputstage or output? The fact that grounding the inputs reduced the problem, make me think it is more input related. Thanks

Guys looks like I have to bother you with another question. After moving the amp to another room to do a provisional listening setup until I manage to case everything up, a hum developed on the right channel. I still hear music on that channel, there is just a medium loud hum. When I disconnect the inputs and short them to ground, the hum is not noticeable anymore. Does this speak for a grounding problem, or could the input j-fets or anything else be broken? Edit: If this helps: The hum gets louder shortly, when I power off the amp (this has something to do with servo, as the Led D1 also lights up a bit more when powering off - but this is the same on both channels and not cause of the problem).

I will take a look if any hum develops once I get everything cased. Just another question: Earlier in this thread someone states that the range of the servo can be increased to -+30v when exchanging the 10k with a 5k resistor. I could use this extra range since I am using the not sooooo stable ixys parts. My offset from cold to warm seems to vary around 30V. Are there any drawbacks doing this modification? FYI: I can now adjust both boards to 0V offset using the VRs after adding replacing the 2k with a 1.8k resistor. Furthermore I would like to use this post to again thank all the people involved in making these projects possible and supporting them with their help in the forum. This is really extraordinary!

Today I finally had the balls to test my freshly built KGSSHV with a source and phones AND THERE WAS MUSIC. Great neutral music and dead quiet! Gotta buy a case and a pot/stepper, box it up and have fun. I wonder. Do you guys have some kind of ground loop breakers in your boxes?

I now replaced Q1 Q2 Q9 and Q10 which I think were all damaged. I am uncertain if I replaced everything I need to. What cause this? Shall I connect I+ and I- to gnd when I power up next time? Could a faulty LSK389 be the cause of this?

Thanks Kevin. Would a 1k resistor be fine? I did a test with both boards still quite warm resistors but I think ok. During testing I had an error on the board that was adjusted to about 0V offset and balance. Everything was up and running. Before I connect anything to the inputs, I wanted to be sure it is safe and I measured the voltage between GND and I+/I-. The inputs were not connected to anything and I measured around 0V from one input to ground and surprisingly 50vdc from the other to gnd. During and after these measurements I noticed a hissing sound to occur from somewhere on the board (no sparking). I cut power and turned it on again. The hissing was gone and then after maybe a minute R17 (20k) got really hot and started smoking. I immediately turned everything off. I removed the 20k resistor, which still measures 20k when off the board. I am unsure what else I should replace. Maybe Q9 and Q10? Should I not have measured what I did, or did this problem occur independently of what I describe? Since the inputs are "grounded" through the onboard 500k resistors I thought it was alright to leave them floating.

I fired up my kgsshv today and it didn't blow!! After a bit of troubleshooting with the psu it works fine. I now have 2 questions. 1. When watching temps with my IR meter I noticed the temp of the high wattage resistors is around 65-70C (with only one amp board connected). Is this alright? Output voltage is fine around 450V. Maybe if I connect two board and draw more power the tranformer output voltage will go down a bit and cause the resistors to dissipate less heat? 2. On one amp board I cannot get the offset lower than around 10-15V. I have not yet used the servo. Do I need to change the 2k resistor to another value or is 15V still ok? When I get the opamp for the servo in standard config, this should be able to regulate another 15. So it would be around 0V. I don't know if its good for the servo to work that hard all the time.

Thats because its a typo and should be stth512fp

I just noticed that I am a retard . I had the input switch on the srm 727 set to rca although I was using xlr... Now it sounds quite a bit better! Anyway, I am still looking forward to my kgsshv. Too bad constructing toroids takes some time...

Ok guys I hope this is the correct thread to post this: Today I did a little for fun A/Bing with the Stax srm 727/sr 009 vs B22/Beyer T1 with the Ressonessence Invicta as a DAC. It is a single ended setup for the T1, where as the Stax is fully balanced. Although these setups have quite some differences in sound, to my surprise, I am not yet sure which I would consider the better combo (I expected this to be clearly in favor of the sr009). Although the stax naturally has a bit more detail, speed and a wider soundstage, I think the T1 combo is more euphonic and has more presence. With the Stax setup I often tend to turn up the volume to achieve that "presence" I like fro the T1. But then, I think especially the higher mids get too loud and it's still not where I want it. When comparing, I think I can clearly hear the deficiencies of the SRM727 as described in the sr009 review at innerfidelity. Therefore I am really looking forward to trying out the KGSSHV which I am currently building! I think it will be in ready for a first test in 2 weeks. I will probably try the spritzer mod for the 727 once i get the kgsshv running, but hopefully this will not be necessary because the kgsshv is sooo gooood Anyone else with similar experiences?

BTW: Why would anyone want to change the feedback with the amp powered on? I would not dare to stick pincers in there when it is on.

I got the same IR receivers as you, when I ordered the 10m90s. But my bag only contained those, not a mix. But I have the correct replacement already.

Ok thank you very much. Do you happen to have the schematic on hand for my version? I don't have it. If you give me your address Birgir, I'll send you some chocolate