Thanks! Measuring before 4.7M to bias output gives me 480V, measuring the zener string gives me 580V. I'm guessing the RCRC filter dropped 100V. I'm also reading... 99VDC at the bias supply output; with reference to ground.

I was using 1A fuse before. It immediately popped at start up. I think startup transient caused it to blow.

Edited June 1, 201214 yr by ujamerstand

I had the same problem the first time I powered my PSU with a 1A fuse.

I am using a 2 amp slow blow without problems.

I am going to order the 10 k Goldpoint. No patience to build a Joshua tree, may be later .

It's killing me that I have a perfectly functioning amp and can't listen to it because I need a volume pot.

Edited June 1, 201214 yr by eggil

The harder something is to attain, the sweeter the victory:).

Thanks! Measuring before 4.7M to bias output gives me 480V, measuring the zener string gives me 580V. I'm guessing the RCRC filter dropped 100V. I'm also reading... 99VDC at the bias supply output; with reference to ground.

I was using 1A fuse before. It immediately popped at start up. I think startup transient caused it to blow.

This could be great news! I just tried powering on my third attempt at the PS yesterday, and the fuse blew instantly... I was going to let my blood pressure lower for about a week before attempting again, but maybe I'll just try a higher rated fuse

1A on a 117V line is a bit optimistic as there is massive inrush current for the first fraction of a second. I use 2A slo-blo on a 230V line with no issues.

Thanks! Measuring before 4.7M to bias output gives me 480V, measuring the zener string gives me 580V. I'm guessing the RCRC filter dropped 100V. I'm also reading... 99VDC at the bias supply output; with reference to ground.

Is the bias supply fully populated? There are effectively two bias supplies there so some parts are left out when you use the regulator.

I left out the voltage doubler. Connected the jumper. The voltage readings at the jumper was about 630VDC.

Here's an image of the wiring when I was testing the negative rail. It should show the parts I left unpopulated.

I'll take a better image tonight when I get home.

Edited June 1, 201214 yr by ujamerstand

Anybody knows what the input impedance of the KGSSHV is?

I'm going to go out on a limb and say "whatever you build it to be"

Anybody knows what the input impedance of the KGSSHV is?

Yours is about 1G or so

Well, if you meant by input as the total amount I have spent so far, its is far more than 1G !

Edited June 2, 201214 yr by eggil

Some images of the bias supply readout:

jumper:

zener string:

before 4.7M resistor:

Overall shot of the bias supply:

Can I assume that the voltage drop over the RCRC filter is normal?

I am having some issues with my attenuator. I am sure is something really stupid.

This is how I have my Goldpoint wired:

XLR 1 (ground) to star GND

XLR 2 (hot) to pot in +

XLR 3 (cold) to pot in -

Pot out + to amp In +

Pot out - to amp In -

Pot Ground not connected (the body is connected to ground but the individual wafers are not, at least when I check for continuity)

This is how I wired it: (Thanks John)

http://www.flickr.co...57629647470956/

I get sound but the volume pot does not control the volume. I am able to control volume directly from iTunes however.

The pot changes resistance if I connect within the same wafer: ground to out

If I connect IN to Out in the same wafer I get a decreasing resistance on the DMM.

IN to ground ground gets me a fixed reading.

I flipped the outputs from the amp to the Stax connector since I am using an off board version and the feedback is flipped.

I have triple checked the wiring and it is done correctly per diagram.

Any ideas?

By the way, it sounds lovely!

The first sounds coming out of it had to be Bach

The Sigma404 sounds so much better. I am still afraid of using my 007, may be tomorrow....

Many thanks to Kevin for his design and help.

Also indebted to Victor, John, Greg, Andy, and Livewire, and of course Spritzer.

Pictures coming soon .....

Edited June 12, 201214 yr by eggil

There should be a ground connection.

If it was a pot the output connection connects to the wiper that travels from the IN connection to the ground and acts as a voltage divider.

Edited June 12, 201214 yr by wink

Congrats! So close now..

I'm also looking for an old pair of sr-sigma for the sigma404 mod. I've already got 404 drivers in storage. I hope I could find a pair somewhere soon...

http://www.tubecad.com/2006/09/blog0079.htm

http://www.head-fi.org/t/195904/6x6-matrix-stepped-attenuator

http://www.tubecad.com/2011/04/blog0204.htm

Thanks Wink. Some people told me grounding the attenuator wold only increase the likelihood of hum in the circuit.

I'll try tomorrow. Would you connect it to star ground then?

I am having some issues with my attenuator. I am sure is something really stupid.

This is how I have my Goldpoint wired:

XLR 1 (ground) to star GND

XLR 2 (hot) to pot in +

XLR 3 (cold) to pot in -

Pot out + to amp In +

Pot out - to amp In -

Pot Ground not connected (the body is connected to ground but the individual wafers are not, at least when I check for continuity)

This is how I wired it: (Thanks John)

http://www.flickr.co...57629647470956/

I get sound but the volume pot does not control the volume. I am able to control volume directly from iTunes however.

The pot changes resistance if I connect within the same wafer: ground to out

If I connect IN to Out in the same wafer I get a decreasing resistance on the DMM.

IN to ground ground gets me a fixed reading.

I flipped the outputs from the amp to the Stax connector since I am using an off board version and the feedback is flipped.

I have triple checked the wiring and it is done correctly per diagram.

Any ideas?

By the way, it sounds lovely!

The first sounds coming out of it had to be Bach

The Sigma404 sounds so much better. I am still afraid of using my 007, may be tomorrow....

Many thanks to Kevin for his design and help.

Also indebted to Victor, John, Greg, Andy, and Livewire, and of course Spritzer.

Pictures coming soon .....

based on your drawing, this should work, provided that "star ground" also includes the amplifier PCB and power supply PCB grounds.

one thing though, XLR pin 1 should not be connected here. it should be connected to the chassis through the shortest path possible. how you connect the chassis to circuit ground elsewhere is another story.

as for the metal body of the attenuator, i would have it conduct to the chassis and dont try to wire it anywhere.

Edited June 12, 201214 yr by justin

Thank you Justin. XLR pin 1 is connected to the chassis only.

When I connected the attenuator ground to chassis, it all works now, and clean as a whistle. No hum whatsoever.

Per Victor's recommendation, I grounded the right + and - together; and grounded the left + and - to a separate post.

It is like I bought a new set of headphones. The Sigma/404 sounds different in a good (wonderful) way.

I am so excited I can hardly contain myself

Congratulations! I am so happy for you. You have come a long way eggil ..... Now enjoy your music:). .

As I said, sometimes "the harder something to achieve, the sweeter the victory".

Edited June 12, 201214 yr by Victor Chew

Congratulations eggil

-- o --

Rodrigo

Congratulations!

I'm very interested in the project and I've been looking through the thread which kind of scares and intrigues me at the same time...

I have a few questions to begin with. First up, I know that there are the off-board and on-board heatsink version. Is there any board-run for the on-board heatsink version happening right now? Or maybe someone has stocked a pile...

Second up, there seems to be many versions of BOM floating around here..... will the BOM in Lil Knight's signature suffice?

I've only built CKKIII and Gamma 2 before, so I don't have any experience with HV stuff, but I'm very cautious. I'm planning to build this mainly for the experience. It probably will take me upwards to half a year to complete, since I don't want to rush it nor do I have the time to rush it as a student. My EE friend is probably going to assist me when I run into trouble.

Replies are appreciated, please no flaming.

Replies are appreciated, please no flaming.

You apparently didn't

1. read your welcome PM very closely and
   
2. lurk here for a bit to get a feel of this place...
   

You apparently didn't

1. read your welcome PM very closely and
   
2. lurk here for a bit to get a feel of this place...
   

hmm I've read the welcome page several times.... and been lurking around here for quite a while now... so I have a general idea of the way conversation goes around here. I'm not afraid to be bashed, but I'm just trying to start from somewhere... that last sentence was just written in courtesy (meaning don't want to be seens as demanding for the first post)

Awesome work eggil, glad you got it sorted it out, well done!

Thanks Justin for your comments about the grounding diagram.

I revised my XLR wiring, connecting pin 1 directly to the grounding lug on XLR itself and not the star ground, as per good old rane notes.

Not finished but the general shape - they’ll be blued later this week, here are Viljo’s knobs for some KGSSHV’s.