DIY forum, Nelson Pass and my ADHD brain. Perfect combination. Now I have something else to focus on.
Nice thing is, I do tend to finish these projects...
So that Nelson does not have to supply 2 extra pairs of matched J113s per kit ?
We had an extensive listening test by different people on various opamp topologies, based on same parts and bias current. etc.
https://www.diyaudio.com/community/...e-opamp-in-dip8-footprint.337484/post-5780747
The double-differential was voted unanimously as the winner, if it means anything.
https://www.diyaudio.com/community/...e-opamp-in-dip8-footprint.337484/post-5780754
Patrick
I don't know if it's just a matter of saving parts. Subjective tests are a must for me. I learned how much can these opamp designs phool you on the M2 front end. Some very famous opamp sounded absolutely horrific as unity gain buffers.So that Nelson does not have to supply 2 extra pairs of matched J113s per kit ?
We had an extensive listening test by different people on various opamp topologies, based on same parts and bias current. etc.
https://www.diyaudio.com/community/...e-opamp-in-dip8-footprint.337484/post-5780747
The double-differential was voted unanimously as the winner, if it means anything.
https://www.diyaudio.com/community/...e-opamp-in-dip8-footprint.337484/post-5780754
Patrick
Forgive me for being ignorant here, but how do the values of R6, R7 and R8 change to accommodate other fets like K369, K389, etc? Aren't these devices N ch as opposed to the P ch J113?
I had also asked previously if there was a simple way to protect the input diff fets from input over-voltage or in the event of a drive signal going in without V+,V- present?
I had also asked previously if there was a simple way to protect the input diff fets from input over-voltage or in the event of a drive signal going in without V+,V- present?
J113 came from Process 51 (no known relation to Area 51 ), and was not considered unsuitable as a "low noise amp."
https://www.onsemi.com/download/application-notes/pdf/an-6609.pdf
I have some higher Idss J111 versions (and a few other types, but not J113), so may try using those here.
P.S.: BVgss is actually listed as 50V "typical."
), and was not considered unsuitable as a "low noise amp."https://www.onsemi.com/download/application-notes/pdf/an-6609.pdf
I have some higher Idss J111 versions (and a few other types, but not J113), so may try using those here.
P.S.: BVgss is actually listed as 50V "typical."
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I displayed and demonstrated a DIY amplifier at Burning Amp Festival, that used the LH0033. But it wasn't an M2x.
Back then, LH0033's were so expensive that I socketed them, and for bring-up & initial testing, built "emulator cards" to fit the sockets. Better to destroy an emulator card or two, than a costly, obsolete, New Old Stock, hybrid circuit. The emulator cards were part of the display, I think Ti Kan's BAF photo essay had at least one picture of them. A photo from my kitchen table is attached below.
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Back then, LH0033's were so expensive that I socketed them, and for bring-up & initial testing, built "emulator cards" to fit the sockets. Better to destroy an emulator card or two, than a costly, obsolete, New Old Stock, hybrid circuit. The emulator cards were part of the display, I think Ti Kan's BAF photo essay had at least one picture of them. A photo from my kitchen table is attached below.
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Attachments
as William found exact post ( which I couldn't remember where it is) , for Boyz wanting more ooomph - don't butcher stage presented in this thread, go build earlier Papa's:
post #90, https://www.diyaudio.com/community/threads/baf2022.391289/post-7182735
you have everything needed, including Gerber files
I moved the discussion to here :
https://www.diyaudio.com/community/threads/the-diyaudio-first-watt-m2x.321925/post-7236810
Patrick
I couldn't resist. I missed ZM's post about the "STASISSY FE" last year. So I've got boards and parts ordered to try it out. I really like the cascoded input devices and the beefy second stage. I'll heatsink those and put 'em to work. It will be a tight fit but I'll do the matched / paralleled K170's for the differential. FE will be configured for 4X gain because I know from experience that's what I need for the gain structure in my system.
A little Stasis heritage... that seems pretty cool...
A little Stasis heritage... that seems pretty cool...
