spritzer Posted February 25, 2013 Report Posted February 25, 2013 That would be possible but pots are problematic. Quote
kevin gilmore Posted March 1, 2013 Author Report Posted March 1, 2013 (edited) 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, 2013 by kevin gilmore Quote
kevin gilmore Posted April 14, 2013 Author Report Posted April 14, 2013 (edited) 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, 2013 by kevin gilmore Quote
justin Posted April 15, 2013 Report Posted April 15, 2013 File not found Sent from my iPhone using Tapatalk Quote
c12mech Posted July 31, 2013 Report Posted July 31, 2013 Has there been any work on this lately? I really want to do this one. 1 Quote
kevin gilmore Posted July 31, 2013 Author Report Posted July 31, 2013 (edited) I have not started on the board yet. I wanted to get a few more things done first Like the squarewave Edited July 31, 2013 by kevin gilmore Quote
c12mech Posted July 31, 2013 Report Posted July 31, 2013 Sounds good. Now I just need to find a nice tube amp for speakers to run with it. Quote
mickey Posted November 28, 2013 Report Posted November 28, 2013 Kevin, why square wave is so important? Quote
spritzer Posted November 28, 2013 Report Posted November 28, 2013 It's the second coming, that's why. Quote
kevin gilmore Posted November 28, 2013 Author Report Posted November 28, 2013 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. Quote
mickey Posted December 11, 2013 Report Posted December 11, 2013 Kevin, have you ever considered NXP BF862? Quote
kevin gilmore Posted December 11, 2013 Author Report Posted December 11, 2013 where is the p-channel to go with it. Quote
wink Posted December 11, 2013 Report Posted December 11, 2013 Seems like it never left the drawing board. Quote
mickey Posted December 13, 2013 Report Posted December 13, 2013 How about PMBFJ177? Or wait for LSJ74? Quote
justin Posted December 13, 2013 Report Posted December 13, 2013 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 Quote
kevin gilmore Posted December 13, 2013 Author Report Posted December 13, 2013 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. Quote
spritzer Posted December 13, 2013 Report Posted December 13, 2013 (edited) 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, 2013 by spritzer Quote
mickey Posted December 14, 2013 Report Posted December 14, 2013 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) Quote
spritzer Posted December 14, 2013 Report Posted December 14, 2013 I bought some and the Idss is all over the place. No way to get any matches from those 8. Quote
justin Posted December 14, 2013 Report Posted December 14, 2013 i would match for Vgs at the circuit current Quote
spritzer Posted December 14, 2013 Report Posted December 14, 2013 For this one then yes. I was matching the Idss for the LL1 as that's how the stock units are matched. Quote
mickey Posted December 14, 2013 Report Posted December 14, 2013 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? Quote
spritzer Posted December 14, 2013 Report Posted December 14, 2013 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. Quote
alexd15z6 Posted January 20, 2014 Report Posted January 20, 2014 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 Quote
kevin gilmore Posted January 21, 2014 Author Report Posted January 21, 2014 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. Quote
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