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...
About the voltage breakdown of J113, I tested a large quantity under conditions similar to this usage and none of them started to leak below 70 volts, so I feel confident in the 50 volt number.
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.
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?
replace just Q1, Q2 with Kosher ones
leave Q3,Q4 as is, they're "just" CCS-es
..... or build "New Stasis FE" without Vbe multiplier and Voila!
protection - you can always put some diodes in few possible scenarios, but why bother ......
leave Q3,Q4 as is, they're "just" CCS-es
..... or build "New Stasis FE" without Vbe multiplier and Voila!
protection - you can always put some diodes in few possible scenarios, but why bother ......
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."
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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Some very famous opamps were abused to act as unity gain buffer when they should not be.
Patrick
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.
_
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.
_
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
With the Stasis driver front end, as is it cannot drive a MOSFET output stage right?
I can attest to the fact that it does make for a nice-sounding amplifier. With a IRFP240/9240 output stage, I could imagine it would be even better than the bipolar stasis amp
I can attest to the fact that it does make for a nice-sounding amplifier. With a IRFP240/9240 output stage, I could imagine it would be even better than the bipolar stasis amp
it can, trivial change of few resistors in Vbe multiplier
choose different or open dedicated thread for that question
choose different or open dedicated thread for that question
Okay. For fun I will compare to the bias circuit of a couple of mosfet amps and see if I can wrap my head around it. First impression is the resistances in the Vbe need to be much higher for mosfet. I'll stop now 🙂
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... 😎
