Makes note to put more pots backwards in the future... 

Edited August 26, 201411 yr by spritzer

Geoff, I can see you use the LSK389, can I ask how you got those? I looked at trendsetter but they want nearly $65 to send $80 worth of transistors to EU and I thought that was a bit steep - do you have another option maybe?

 

//UFN

Choose a Linear systems distributor near you

 

http://www.linearsystems.com/distributors.php?reg=Europe%20and%20the%20Near%20East

As a noob to building amps to power electrostatic headphones, I found this linked thread started by Birger very helpful in my upcoming build.

A lot of valuable info is there for the reading and a great reference.

For the other noobs building the KGST.

Edited August 26, 201411 yr by Laowei

I just finished assembling the boards. Have a look: 

 

Still waiting for the toroid though. Anyone else notice that the mounting holes of the PSU board are huge?

Yeah, spotted the hole snafu when resizing the board over the weekend. 

I measured the holes when ordering screws and standoffs.  I'm going to be using 1/4 inch hex 4-40 standoffs and screws for the amp boards and 5/16 inch hex 8-32 standoffs and scews for the PSU boards. 

Edited September 4, 201411 yr by chiguy

There’s a large vacant hole in-between the two tubes, a standoff here would probably help alleviate flexing changing tubes. 

This thread reminds me I still haven't received boards. Has anyone in the US gotten boards yet?

This thread reminds me I still haven't received boards. Has anyone in the US gotten boards yet?

Yes, weeks ago.

That's not a good sign. If the package doesn't show up tomorrow I'll contact headinclouds about what to do.

There’s a large vacant hole in-between the two tubes, a standoff here would probably help alleviate flexing changing tubes.

That hole is used to route the wires to the screw terminal block for the floating tube heaters.

Edited September 5, 201411 yr by Laowei

Ahhh... ok, thanks Laowei.

This thread reminds me I still haven't received boards. Has anyone in the US gotten boards yet?

 For some reason a couple of packets seem to be stuck in Kennedy NY.  Perhaps customs hold them up?  I have pm'ed you with details.

 

Edit; to give feedback on this.  NY Kennedy is where the packets disappear from UK tracking.  I found on USPS that a couple were still in the system for various reasons.

Edited September 5, 201411 yr by headinclouds

That would be customs.  Been down that road many times but USPS tracking is the worst. 

Hey guys, as you can see I ordered and soldered in the tube socket recommended in this thread. http://www.ebay.com/itm/10-9pin-Ceramic-Tube-Socket-PCB-B9A-6DJ8-12AX7-ECC83-ECC82-12AU7-6922-6N11-Valve-/140891822701?pt=Vintage_Electronics_R2&hash=item20cdce9a6d

Since I have no experience with tubes, I am unsure how hard I need the push to get the tubes into the sockets. To me it seems almost impossible to get one in. I'm scared of breaking it. 

 

Help?

use the rear end of a drill bit the right size to open up the holes.

some of those sockets are real garbage

That did the trick. Used a 1.1mm drill bits end. 

The bit has broken two times during the process, but the tubes fit in well now. 

Geoff, I can see you use the LSK389, can I ask how you got those? I looked at trendsetter but they want nearly $65 to send $80 worth of transistors to EU and I thought that was a bit steep - do you have another option maybe?

 

//UFN

Apologies for quoting myself, but in case anyone needs it: I ended up ordering LSKs from Micross in the UK. Postage was a bit steep at 15 pounds, but I ordered on Sunday and parts arrived Thursday, so no issues to report there at all

 

//UFN

Edited September 5, 201411 yr by UFN

Has anyone already made up their mind on what case to use for a KGST? Total height of the board to the tubes end is 75mm. With 10mm studs we end up at 85mm which is too much for 2U. 

Either I have to go for 3U or find a case which has around 90mm internal height. 

 

I don't think that using studs shorter than 5mm is a good idea.

A couple of questions from a DIY wannabe. Is this easy enough to build as a first project for someone who barely can solder? Will it decently drive the 007 (I mean 717 level of driving) at 350V in the PS?

I've read that Kevin recommends the 400V configuration, but Birgir tried 350V and I'm not sure about the results. 400V trafos are a bit more expensive.

As usual with these DIY electrostatic amp projects, soldering is one thing. But you have to be aware of the high voltages involved and it is also useful to have a bit of an understanding of electronics. I mean you don't have to fully understand how the amp works, but electronics basics are essential. Otherwise you will end up blowing the whole thing up or killing yourself. Furthermore if you commit on doing this project, I suggest carefully reading other threads in the forum, such as the KGSSHV thread. 

With the right tools then it is certainly possible to build this without much trouble.  Stick with a good soldering iron with a small chisel tip, thin solder wire (I use 0.5mm) and taking care to only use as little solder as it possible.  Also cut the leads after soldering up close to the PCB as the density of these boards is reaching silly levels so pads can be very close together but should not be connected. 

 

The main issue would be the heatsinks and how to assemble them properly.  The full B+ sits on the 10M90 transistor tab so this needs to be insulated. 

 

As for the rail voltages, the amp is supposed to run at +/-350V but I usually run them at 400V.  No real improvement by doing that but I've been using up my scrap BHSE transformers which can't deal with that load. 

 

Ohh and this amp eats the 717 for breakfast... 

 

Has anyone already made up their mind on what case to use for a KGST? Total height of the board to the tubes end is 75mm. With 10mm studs we end up at 85mm which is too much for 2U. 

Either I have to go for 3U or find a case which has around 90mm internal height. 

 

I don't think that using studs shorter than 5mm is a good idea.

 

Lowest I've dared to go for standoffs is 6mm and then the boards fit in a 2U chassis but I have to select what tubes to use. 

 

Parmetal might have some boxes that work better as they aren't as fixed into the 40/80/120mm sizes. 

Lowest I've dared to go for standoffs is 6mm and then the boards fit in a 2U chassis but I have to select what tubes to use.

Good point, many thanks.

Edited September 6, 201411 yr by PICaudio

Thanks, Birgir. Maybe 350 V is just enough for a beginner.