Buffer For Blues

Interseting.. When are you going to test it ?

i'm sure he has a pretty good idea that it works

Nelson Pass said:

BUFFER FOR BLUES...

I am posting this as general interest rather than burying it
in an existing thread. It is a JFET input buffer for the ZV4.

It has not been tested.

Click to expand...

Wow, straight from the Zen Master! Thank you, sir. I am currently playing around with a buffer jfet connection like you described at the other thread. The voltage gain is still quite high and I'm trying to find a way to lower it. I'll just scrap that and use this one. I can only sim it right now because my Woody Zen is in WA state...I'm in Californi-A!

Weather is nice here in victoria T00 !

Weather in AZ is nice now too. Where can one find the part number for the JFET?

Enjoying perfect SoCal weather now for 5 months...it is really Sun Diego here.

Nelson Pass said:

The Source voltage on the JFET should be 10V not 13V.

Click to expand...

Superstitious ?

Supposing the mentioned 2SK170 or 2SJ74 for the JFet.
Any other suggestion for a JFet (and where to get it)?
Allan, can you already vision the 8th Blues Buffer version ?(no W!)

Weather sucks big time overhere , but don't let that discourage you guys.

BUFFER FOR BLUES...

Click to expand...

Great When will you guys stop Now I will have to rebuild the Zen, once again

Steen

Maybe it isn't necessary to use the excotic Hitachi devices?
Would these be usefull for the JFET-buffer?
http://www.onsemi.com/pub/Collateral/2N5460-D.PDF

Steen

jacco vermeulen said:

Superstitious ?

Allan, can you already vision the 8th Blues Buffer version ?(no W!)

Click to expand...

Jacco,

NP superstitious? I've seen some of his mosfets biased at about 666.7mA

Next will be "Blues Buffer's Brother".

Steenoe, as designed by NP any Jfet that can take Vds=10V or more and about Ids=140mA(?) or more.

I was kinda wondering myself too if one of ON JFET's are any good.
ON does produce quite a bunch of them.

Actually i was more thinking of an Elliot's challenger when i read 666s :
"Blues Buffer B**ch"
Somehow i always visualise Rod as Darth Vader.

On Semi parts work just fine. Get as high an Idss & high transconductance part as they offer.
No reason to get boggled, it's a Source follower, just 'upside down' due to the input being a P device.
Enjoy.

Grey

I have the 2N5462 designed into the front end of my PLH proto(similar to fig;5). I'll be lighting it up for the first time today The 2N5460 series seems to be quite high on the noise figure but I did not get to excited over to many other ON devices... I've never done anything J-FET before. We will see where I end up.

Zen v4jfet Cascoded

Blues said:

Jacco,
Next will be "Blues Buffer's Brother".

Click to expand...

Found time to look for the lost brother. Anybody care to try this? Comments? Let me know if I missed something.

The jfet will dissipate about 100mW. Using the 2sj74 it will have about 4x safety margin with about 7V of stable Vds across.

Has anybody tried lower than 10Vds on a 2sj74 and still kept the coveted jfet sound? Now if only the guy selling 2sj74s will get back with me I'll have something to do this Christmas holiday.

Allan

hello Blues

I attach a small image of your zip.
Hope it is alright.
Makes it easy for lazy folks to view

Pass circuits almost every time
has got some interesting details.

Regards
lineup

Thanks Lineup! That's much better.

Now if only the guy selling 2sj74s will get back with me I'll have something to do this Christmas holiday.

Click to expand...

Hi Blues. Where do you get the SJ74? I just had a bunch from Ruach, selling J-fets in the "Marketplace" Actually the postman delivered them today
Nice schematic indeed, thanks for posting.

Steen

http://www.diyaudio.com/forums/showthread.php?s=&threadid=86778&perpage=10&pagenumber=1

Nelson, I would have a pulldown resistor at the input just to avoid accidental charging of the input cap. Resisitor value 100k-1M