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SEN I/V stage for BIII


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I don't think the original boards are available and I think the 2SK369V are out of production.  As far as the heatsinks go they look like they were made just for the original group buy a few years ago and haven't been made since.

My thoughts and or questions are:

1. is there an equivalent to the 2SK369V through hole or smt that we could match?

2. would someone be willing to layout the board

3. we should be able to find a heatsinking solution

What are your thoughts

Edited by sbelyo
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is there an equivalent to the 2SK369V through hole or smt that we could match?


Any JFET with preferably lower noise, higher Idss and higher transconductance.
Say, LSK170 grade C or D

You can tie upper transistor gate to a potentiometer and correct DC shift at the output.

would someone be willing to layout the board


Yeah, nice joke.
Please let me use it from time to time!

Since when layouting of 2/4 transistors became a problem?
:)


we should be able to find a heatsinking solution


1. Cascode.
2. Mount from bottom and thermalgrease to case panel
3. 2-3-oz PCB with thick traces and ground plane
4. 3/8" air conditioner copper pipe
5. Just bend JFET case to a ground copper plane and add some thermalgrease.
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6 minutes ago, Bespav said:


Yeah, nice joke.
Please let me use it from time to time!

Since when layouting of 2/4 transistors became a problem?
:)
 

 

It is indeed funny, but I have no layout software or experience. I know, I suck

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Re: 2SK369V

This guy on diyaudio has them, but is in W. Australia with large shipping costs. Genuine devices though. You need 4 quads matched (16 devices)? You would probably need to buy 100 devices to guarantee this level of matching (and nothing is guaranteed). Might get lucky with 50...

http://www.diyaudio.com/forums/vendors-bazaar/297423-toshiba-2sk170-2sj74-fets-other-semis-sale.html

I had some stuff I needed and would consider piggybacking an order to split shipping if you decided to go this route.

 

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luvdunhill might match these for you, but you would need to contact him. He has a curve tracer (locky_z), and likes doing this kind of stuff. I'd ask his opinion on how many devices you might need to get a good match for 4 quads. I could probably do the board layout for you and integrate the es9018 stuff if you wanted that on board.

Edited by Pars
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I saw a bunch of posts saying this was a whole different ballgame compared to the ivy or legato. But it seems like a lot of work and the cost of sourcing hard to get parts.

Maybe it would be worth it if there were parts we could use that are currently available. What do you think ?


Sent from my iPhone using Tapatalk

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Maybe it would be worth it if there were parts we could use that are currently available. What do you think ?


Yes.
LSK170D + Cascode 2SC3503.

Increase I/V supply to about +- 100-150 Volts.

And you just need to simply bufferize I/V output via some kind of good follower.

You can even take well known Pass F5 and realign it's input and ground like this:
4374734a122fce5d1dcaa29a99d0a849.jpg

Let your DAC output current to flow there.
:)

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8 hours ago, Bespav said:

 


Yes.
LSK170D + Cascode 2SC3503.

Increase I/V supply to about +- 100-150 Volts.

And you just need to simply bufferize I/V output via some kind of good follower.

 

You can even take well known Pass F5 and realign it's input and ground like this:
4374734a122fce5d1dcaa29a99d0a849.jpg

Let your DAC output current to flow there.
:)

High voltage, hmm  maybe worth a shot but there's this

http://www.diyaudio.com/forums/digital-source/195483-zen-cen-sen-evolution-minimalistic-iv-converter-188.html#post4961030

And, I heard back from someone that had it working with the BIII albeit in single ended config he said it sounded weak and sold the setup.  Then reading a bit further someone else reported the same.  There are two people that may have working ver 18 boards that they're willing to sell and are to get back to me soon.

Let me do some more research

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