That would be possible but pots are problematic. 

so it turns out the hawksford already came up with the idea of cascading a current mirror (well sort of)

http://www.essex.ac.uk/csee/research/audio_lab/malcolmspubdocs/J10%20Enhanced%20cascode.pdf

 

it also turns out that the single ended version where you ground the input, and then drive the emitters

makes an absolutely wonderful I/V converter for your favorite dac.

also previously released in a simplified version by pedja rogic.

http://gilmore.chem.northwestern.edu/privstage.pdf

 

so the building blocks are now piling up.

need a really sweet output stage (not the headphone kind)

and this preamp should be able to compete with the big boys.

Edited March 1, 201313 yr by kevin gilmore

this is getting very close now to the final input stage

 

http://gilmore.chem.northwestern.edu/ubaltobal2.pdf

 

 

extra cascade stage allows power supplies at +/-20 volts

distortion at about .008%

 

fixed it.

Edited April 15, 201313 yr by kevin gilmore

File not found Sent from my iPhone using Tapatalk

Has there been any work on this lately?  I really want to do this one.

I have not started on the board yet.

I wanted to get a few more things done first

Like the squarewave

Edited July 31, 201313 yr by kevin gilmore

Sounds good.  Now I just need to find a nice tube amp for speakers to run with it.  

Kevin, why square wave is so important?

It's the second coming, that's why. 

well there is this

http://gilmore.chem.northwestern.edu/sqss1.jpg

 

I'm not going to finish the ultimate preamp till a reliable source of audio grade complementary jfets

is available. Too many fakes out there to design with old stuff, and linear systems is a bunch

of incompetent fucknuts. But I do have a working one on the bench. It has to be a jfet input otherwise

the input impedance is too low and the bipolar parts have too much offset with high impedance sources.

Kevin, have you ever considered NXP BF862?

where is the p-channel to go with it.

Seems like it never left the drawing board.

How about PMBFJ177? Or wait for LSJ74?

How about PMBFJ177? Or wait for LSJ74?

 

LSJ74 now is available to DIYers, except you can only get like 2 per person. i think next they'll be putting 1 FET in every box of raisin bran

 PMBFJ177  is equivalent to the piece of shit cavalli is using in his overpriced pieces of crap

and it sounds like absolute dogshit too.  designed for switching use. not for analog audio.

Changing from the J176 to tightly matched J74's was not a subtle change in the LL1.  All matched to identical specs... 

Edited December 14, 201312 yr by spritzer

LSJ74 pricing

Grade A (Idss 2.6 - 6.5): 8 pieces $53.04 ($6.63 each)

Grade B (Idss 6 - 12): 8 pieces $50.16 ($6.27 each)

Grade C (Idss 10 - 20): 8 pieces $47.28 ($5.91 each)

Grade D (Idss 20 - 30): 8 pieces $47.28 ($5.91 each)

I bought some and the Idss is all over the place.  No way to get any matches from those 8. 

i would match for Vgs at the circuit current

For this one then yes.  I was matching the Idss for the LL1 as that's how the stock units are matched. 

I bought some and the Idss is all over the place.  No way to get any matches from those 8.

Don, are they within the claimed range?

They are and if people would pool a number of purchases then I'm sure there are some nice matches to be found.  Personally I'd just wait until Linear fill those few million unit orders and these will be available in mass. 

Hi ! 

Sorry for hijacking the tread ))

I check this tread and find only schematic for Vendetta - if i miss something -i am sorry.

Any chance to see the board picture for this phono stage clone - or even order one through the GB ? 

I am quite interested to make this unit - heard a lot of good reviews of this one.

 

Thanks in advance 

With  respect

Alex

was not planning on doing the phono stage. have not played a record in 20 years.

here are pictures

.http://amp8.com/tr-amp/foreign/etc/scp-2a.htm

getting and matching parts would be almost impossible.

there are schematics floating around somewhere.