Jump to content

i'm on a roll... the kgsshv


kevin gilmore
 Share

Recommended Posts

I is in for GB for mini psu boards. Btw with the weight of that trafo have you noticed any sag with the bottom metal plate? I have one of those cases (I mentioned while back) or it might be a bit bigger from ebay and was planning to turn it into a F5 build but unsure bottom plate (quite thin - about 3mm?) can sustain a heavy 300va trafo in the middle (for that matter that toroid looks about same size as my 300va toroid, heavy 7kilo bastard).  :-

Link to comment
Share on other sites

I recall Stax saying that improvements on the current line would mean large heatsinks and that was supposed to increase costs more than the audible benefits. Now you have regulated power supply, more current and more voltage in comparable package. Nice proof of concept. I hope Stax licenses the boards from KG to mass market a similar platform. Do you think EI transformers with same current would fit? Congratulations! 

 

Zero chance Stax would ever do something like this.  First off they would fuck with the circuit to make it "warmer" and then try some further tuning to make up for issues in the transducers. 

 

EI or R-core transformers would work just fine but both are difficult to get as one off units at a sane price. 

 

I is in for GB for mini psu boards. Btw with the weight of that trafo have you noticed any sag with the bottom metal plate? I have one of those cases (I mentioned while back) or it might be a bit bigger from ebay and was planning to turn it into a F5 build but unsure bottom plate (quite thin - about 3mm?) can sustain a heavy 300va trafo in the middle (for that matter that toroid looks about same size as my 300va toroid, heavy 7kilo bastard).  :-

 

Your chassis must be far bigger as no way a 300VA unit would even fit in these one.  The transformer in there is a 100VA unit.  The F5 also needs a far larger chassis to have any hope of staying cool.  Something like this then:

 

tEYl4aHh.jpg

MZd1oCbh.jpg

 

This one could perhaps work on a scaled down F5 as the sinks are huge.  A word of warning though to anybody who might buy one of these, the anodizing on the sinks washed off with the cutting oil after I tapped the holes.  Clearly a quality finish... 

Link to comment
Share on other sites

Goes to show just how fucking complex this PCB is.  Also servo was added without enlarging the board...  :)

 

Ditto ^^^

 

Impressive build!

One could make it 1/3 smaller yet.

Stand the trafo on it's side - bolt it to the back panel, then chop a chunk off the heatsinks.

Heat rise and noise would need to be evaluated.

 

No space for connectors if the transformer was mounted to the back panel... 

Link to comment
Share on other sites

I would let the amp warm up to it's full running temp before adjusting but yeah, that's the procedure.  Same as on the new KGSSHVk boards. 

 

There is also a jumper connection for the servo so you can simply engage it that way when you want. 

Link to comment
Share on other sites

Well the big brother of the mini KGSSHV I posted above is up and running.  Huge sinks on this one so I could play with the current a bit.  Running at almost 12mA now @+/-400V... 

 

fYaGvDMh.jpg

Q76BlvVh.jpg

 

Not happy with the quality of these boxes though so this one will be a one off.  Managed to wash some of the anodizing off the heatsinks...

  • Like 2
Link to comment
Share on other sites

Hello all. I am a new member to this group, but have been following the KGSS threads for a while now and am planning on building a KGSSHV amp in the near future. I have been a user of electrostatic speakers for some time, and have rebuilt a pair of vintage Acoustat 2+2 speakers. I am curious about the board layout picture from Kevin Gilmore a few pages back with the doubled up transistor stages. What are the advantages of this compared to single transistors and has anyone built a prototype of the circuit shown ?

 

The KGSSHV that I have in the works will use the onboard power supply and offboard amp boards. I have built a stepped attenuator (revol3) for 64 step volume control. I was also going to allow both balance and unbalanced inputs. The unbalanced inputs would be converted to balanced before being routed to the volume control. I have not decided whether to put in one or two enclosures. If I use two, I may separate the bias voltage generating on circuitry from the power supply and put it in the box with the amp boards. Less wires to connect between the two boxes that way. I would also incorporate two plugs, one for standard and one for pro bias.

  

Does anyone know a source for boards or a fabricator that does small lots at a reasonable price? I could etch boards myself, but at these voltages I would prefer a professionally made board.

 

The acoustat speakes that I rebuilt were originally powered by their own OTL tube output amplifiers. I stopped using them a while back and converted to a standard amp with a stepup transformer. The 6HB5 output tubes were getting expensive and hard to find and they needed replacing every 2-3 years. Has anyone considered the Gilmore amp as the early stages of a high powered speaker amp with a final voltage stepup via tube at the end? The acoustat amps output 5000V peak to peak as I recall.

Link to comment
Share on other sites

I owned a pair of acoustat's for a number of years. Messing with that amp definitely no fun.

 

 

build a megatron with 3-500z and + and - 2500v power supplies.

and appropriate rated interstage coupling cap.

 

not going to be cheap. but will be glorious.

 

since they have to be monoblocks anyway, it won't be that huge.

 

Don't do this unless you really know what you are doing.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...