As you can see in the pic (post#1) I did it on the perfboard - heavy wires underneath...
A moderator that asks a question that's been answered in the first post of the thread... ts, ts, ts...
Look at the output char. of the VFET and you'll see that k60 needs it's gate at 10V lower potential than the source (and vice versa for j18). Since the source of k60 sits at -25V, the gate has to be at -35V so when we want the common source (drain follower) output stage it's only logical to use higher voltage rails in the front end (biasing) stage.
Juma, and tinitus. Zen Mod has referenced this thread in his new thread "Ultrasimple SIT.." [post #11] to emphasize that two dual PSUs; one higher or double the other, are needed for the schematic shown by Mr. Pass at 2013 BA Festival.
As you can see in the pic (post#1) I did it on the perfboard - heavy wires underneath...
Thank you
I was wondering what those big caps were. hahahaha
Since the big heatsinks for this amp won't arrive before Christmas I bought some (locally available) smaller ones to continue testing in next few months.
I chose to mount the PCBs and VFETs in such a manner that provides an easy access to both sides of the PCB (for easier change of components). Even the whole PCB can be replaced/taken out without much effort and without taking the case apart.
Construction is mechanically very strong (although it doesn't look like that) because 2 supporting solid copper wires are very thick (3mm) and the drain connection doesn't allow movements to opposite direction.
I chose to mount the PCBs and VFETs in such a manner that provides an easy access to both sides of the PCB (for easier change of components). Even the whole PCB can be replaced/taken out without much effort and without taking the case apart.
Construction is mechanically very strong (although it doesn't look like that) because 2 supporting solid copper wires are very thick (3mm) and the drain connection doesn't allow movements to opposite direction.
Attachments
A good DIY-friend of mine, Harry, asked me, if it is possible to do a layout for this amplifier and get some professionally-etched PCBs.
Harry: this is of course possible! Find attached an image of my current layout! (The size of the PCB is: 100 x 66 mm)
The only concern that I have, is:
My EAGLE-library does not contain the package for the SONY TO3 - output transistors (2SK60 resp. 2SJ18).
Nor am I able to GOOGLE the pinout for the SONY transistors.
I took any (!) BJT - TO3- transistor instead.
Is my EAGLE-package correct?
If you (or anybody else) can answer my question:
I will happily offer you a pair of professionally etched PCBs (1,6mm - FR4-PCBs, 2-layers, 70µm copper) for 15€ (worldwide shipping is included).
JUMA: Is there any alternative instead of using the SONY - TO3s? They are very hard (and expensive !) to get.
I will do and offer you the proposed alternative in a minute!
Best regards - Rudi_Ratlos
Harry: this is of course possible! Find attached an image of my current layout! (The size of the PCB is: 100 x 66 mm)
The only concern that I have, is:
My EAGLE-library does not contain the package for the SONY TO3 - output transistors (2SK60 resp. 2SJ18).
Nor am I able to GOOGLE the pinout for the SONY transistors.
I took any (!) BJT - TO3- transistor instead.
Is my EAGLE-package correct?
If you (or anybody else) can answer my question:
I will happily offer you a pair of professionally etched PCBs (1,6mm - FR4-PCBs, 2-layers, 70µm copper) for 15€ (worldwide shipping is included).
JUMA: Is there any alternative instead of using the SONY - TO3s? They are very hard (and expensive !) to get.
I will do and offer you the proposed alternative in a minute!
Best regards - Rudi_Ratlos
Attachments
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Steve, I have never before come across your datasheet of the used SONY-TO3s in the past.
Thanks a lot - I will evaluate my EAGLE - package now (maybe tomorrow).
Best regards - Rudi
P.S.: I only know about the OCR- scanned hardcopies of the SONY-TO3s. But they are impossible to read.
Thanks a lot - I will evaluate my EAGLE - package now (maybe tomorrow).
Best regards - Rudi
P.S.: I only know about the OCR- scanned hardcopies of the SONY-TO3s. But they are impossible to read.
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2sk82/2sj28 are somewhat stronger pair of VFETs that would fit fine (with some tweaking) in this amp. I can't do the tweaking because I don't have these VFETs to test and measure - it's too complicated to buy ebay stuff from my country.
As a source of genuine 2sk82/2sj28 Mr. pass recommends ebay member acronmanelectronics:
Vfet Sony's RARE 2SK82 and 2SJ28 Ke 33 Vfet 1 Pair | eBay
Edit: about the SONY VFET TO-3 package - yes, it's a standard TO-3, measures are the same as any other TO-3 part.
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Thanks Massimo but no need for that. We have guys here skilled in ebay trade, it's just that it's too bothersome/complicated for me - if I have a choice I'd rather be a walk-in-the-shop-and-buy-stuff kind of a guy...
If I would have to wait a courier service to bring me a bag of parts every time I feel like building something I would abandon electronics...
If I would have to wait a courier service to bring me a bag of parts every time I feel like building something I would abandon electronics...
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Not really - the last thing I did about this amp is in post #45.
Now I can listen to the amp for about half an hour before I have to switch it off because the heatsinks get too hot.
That's pretty much it. I don't think I'll change anything in final version, but my big heatsinks are supposed to arrive in about 2 months and who knows what can happen by then...
At the moment it's a pretty unwieldy contraption as it is, let alone the fans.
OTOH I have a pair of extremely silent NOCTUAs that beg for some action... I'll come to that yet, these days I'm occupied with, as Buzz named it, ouroboros preamp which was presented by Mr. Pass at BAF 2013
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