i'm on a roll... the kgsshv

[insanity]

on board version already has this and had it for quite some time.

some off board versions already have this

 

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

[kevin gilmore]

early off board versions had it, but not the servo.

birgir is working on the latest board to add the other

current sources

[spritzer]

Yup, too busy building amps to work on it though. 

[sneeze]

hi! anybody want sell kgss?

[Nebby]

Nope.

[kevin gilmore]

just build one.  take current kgsshv board and populate resistors instead of current source.

[spritzer]

I have enough parts to build two more KGSS units so they are on my todo list. 

[DouglasQuaid]

I still haven't bothered to put a pretty knob on my kgss.  It stilll has some undersized mouser knob I had originally planned to put on a little hammond case.  Perhaps I shall make it a plan to finish this one up before you build two new amps.

Edited April 29, 2014 by DouglasQuaid

[nopants]

http://www.vt4c.com/shop/program/main.php?group_id=2&cat_id=6

 

not the best knob store but it has quite a few options

 

I think the most appropriate knob would be a base upon which the amplifier sits, and you rotate the amplifier to adjust the volume

[DefQon]

Or have one custom milled out of a fresh billet of alu or some nice grain revealing wood. I'm thinking nice stained wooden cheeks on my offboard KGSSHV and wooden knob, wish it could drive speakers as there is literally no e-stat in this house no more (or headphones for that matter). 

Edited April 30, 2014 by DefQon

[spritzer]

I still haven't bothered to put a pretty knob on my kgss.  It stilll has some undersized mouser knob I had originally planned to put on a little hammond case.  Perhaps I shall make it a plan to finish this one up before you build two new amps.

 

You'd have to be quick as the chassis for those two amps are already on their way to me.    All the boards are ready and have been for months so it's just a matter of doing the chassis stuff. 

 

I have so many half finished projects like this that need to be finalized.  Way too bloody many... 

[spritzer]

So a couple of things.  First, see this:

 

 

Looks just like all the KGSSHV's I've built but this one is different.  Aside from the 2SK170 input fets it's all in current production.  It runs at +/-400V but with just over 8mA of current and uses Fairchild FJPF2145 output devices.  Sounds pretty much indistinguishable from a +/-500V version I built as well that is pretty much identical save for the output devices and voltage. 

 

Now a couple of neat points about doing the amp this way, first of all the parts are all easy to source and secondly, so are the transformers.  Edcor has a nice dual 335V winding unit in their catalog so add a small 30VCT/25VA unit and you are set.  No need for anything custom and the PSU mods are dead simple.  Just change the zener string and the divider and bypass the voltage divider that feeds the bias supply. 

 

The second point is that I've finally given up on thePMBFJ620 fet.  Nothing wrong with it except it is just so bloody tiny that it's all but impossible to solder.  They will be removed from future versions of the boards and might be replaced with the SMD LSK389. 

[DefQon]

How much does Edcor charge for the custom toroidial's built per KGSSHV PS spec?

[nopants]

it's not custom, and it's 50$. built to order so some lead time

[demented badger]

I noticed that Antek has a dual 430V / 0.46 amp toroid model AS-4T430 on their website. It also includes dual 6.3V outputs. It is reasonably priced at $57.00. Does anyone have any experience with this transformer for the KGSSHV ?

[spritzer]

The Antek units I've tried have all been excellent.  Something like that 400VA unit is gigantic though... 

[demented badger]

It is big. Five inches in diameter by three inches thick and weighs 9 pounds.

[nopants]

better served for dual psu megatron

[spritzer]

That would qualify as massive 

[DouglasQuaid]

It's a bit overkill, and those 6.3V outputs would only be useful to you if you wanted to link up some digital circuitry off a second psu.  You'd still need to fit a second transformer in there somewhere.

[mypasswordis]

It is big. Five inches in diameter by three inches thick and weighs 9 pounds.

 

It's actually closer to 5.5" in diameter. I'd recommend asking Antek when the 350V 200VA trafo will be back in stock.

[DefQon]

it's not custom, and it's 50$. built to order so some lead time

 

Wow that's pretty cheap excluding shipping costs to down-under. A lot cheaper compared to the $128 a local supplier is asking for.

[demented badger]

Here is a KGSSHV onboard power supply board design modified to include both normal and pro bias outputs. I moved things around a bit so that everything would fit on an 8 X 8 board. I have removed the ground plane from the second picture to make the rest of the circuit more visible.

 

 

 

 

 

 

 

[kevin gilmore]

current mini power supply board is 6.92 x 6.56 inches.

 

low bias is just 3 resistors off of the positive regulated voltage.

[DefQon]

In case anybody here is interested in sourcing parts.

 

http://www.ebay.com/itm/301165029880?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1558.l2649