Rather nice on test speakers. Had a couple moments of surprise/spookiness even with them.
I hope to hook them up to the Zu's next weekend. (So far, I've only used the Zu's with the ACA Mini.)
I hope to hook them up to the Zu's next weekend. (So far, I've only used the Zu's with the ACA Mini.)
Congratulations Dennis! Fugly!!! 
Yes, it does have a slight negative tempco. Now what else can we build with these fellows?

Yes, it does have a slight negative tempco. Now what else can we build with these fellows?
Thank you Stephen.
I'm perfectly fine with a slightly negative tempco. 🙂
How about a simplified version running without gain?
Cheers,
Dennis
I'm perfectly fine with a slightly negative tempco. 🙂
How about a simplified version running without gain?
Cheers,
Dennis
Hehe. Around minute 4…
https://www.diyaudio.com/community/...ff-topic-thread.135674/page-1383#post-6911697
https://www.diyaudio.com/community/...ff-topic-thread.135674/page-1383#post-6911697
I know that Pras had ( maybe still have them) those big Ge Papa did show around min 4
Though, according to datasheets, 2N1099 are superior in temperature domain and maybe even power wise, so I didn't pull that trigger
dunno , still question mark, is that comparison truthful or not, only real tests can show ........ anyway - small stash of 2N1099 I have, snatched in few different ocassions, did show that each of them is trouble free
but, as experience did show - with all these old ones - in first time you must deal with them as they are TNT, ready to blow every second
Though, according to datasheets, 2N1099 are superior in temperature domain and maybe even power wise, so I didn't pull that trigger
dunno , still question mark, is that comparison truthful or not, only real tests can show ........ anyway - small stash of 2N1099 I have, snatched in few different ocassions, did show that each of them is trouble free
but, as experience did show - with all these old ones - in first time you must deal with them as they are TNT, ready to blow every second
Just a quick update. I consider my Old Soul to be complete as it sounded lovely as is. It's very quiet, quite cool running, and the only the hiccup I had was my bad luck with some 2n1099 devices. To me, it's an amp well worth building and I hope others will try it.
Thank you Mighty ZM for sharing this with us.
My next amp project will be something larger (5U/500) and hotter running. Unfortunately with some stuff happening here I likely won't be able to start till May...
Cheers,
Dennis
Thank you Mighty ZM for sharing this with us.
My next amp project will be something larger (5U/500) and hotter running. Unfortunately with some stuff happening here I likely won't be able to start till May...
Cheers,
Dennis
Congratulations Dennis !!!! glad all worked out - looking forward to your next build 🙂
Hopefully mine will be up and running soon - "case" work takes forever for me
Hopefully mine will be up and running soon - "case" work takes forever for me
Sounds like wonderful idea. Are you trying to tempt us now. 😀😀😀
I can't wait to see what wonderful woodwork you will do for your case.
Cheers,
Dennis
Thanks Bob.Congratulations Dennis !!!! glad all worked out - looking forward to your next build 🙂
Hopefully mine will be up and running soon - "case" work takes forever for me
I can't wait to see what wonderful woodwork you will do for your case.
Cheers,
Dennis
Bad ZM! Bad ZM!shall we try DEF stage with Toob and Mosfet now?
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Bad ZM! Bad ZM!shall we try DEF stage with Toob and Mosfet now?
![]()
I am in. lu and fets awaiting a tempting projectshall we try DEF stage with Toob and Mosfet now?
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shall we try DEF stage with Toob and Mosfet now?
![]()
I'm game !
😀
No, really !
Let's see, an EL84 needs about -10V of bias ... if I take the SissySIT R.3 biasing method, at 30 mA from the current source, we are looking at a level shifter resistor of 330R, with a dissipation of 300 mW ... s, a 1W or 2W resistor should be fine ...
We would need an output transformer ... would a P-P transformer work, or would you need an SE transformer ... bias currents can be made to cancel, but what about signal current ?
... or am I too fast ? 🤓
Regards, Claas
I‘m out. No need for a fifth diy-OS.
That phono-stage you once bragged about would be tempting though
That phono-stage you once bragged about would be tempting though

Just a quick update. I consider my Old Soul to be complete as it sounded lovely as is. It's very quiet, quite cool running, and the only the hiccup I had was my bad luck with some 2n1099 devices. To me, it's an amp well worth building and I hope others will try it.
Thank you Mighty ZM for sharing this with us.
My next amp project will be something larger (5U/500) and hotter running. Unfortunately with some stuff happening here I likely won't be able to start till May...
Cheers,
Dennis
Congratulations on crossing the finish line Dennis! I hope you will have many chances to enjoy Old Soul while you wait for May to come around.
DEF + Tubes + Mosfet?? This greenhorn cannot resist 🙂
DEF with tubes - I was joking .....
I mean, I believe all got it from the start, but just in case .....
I mean, I believe all got it from the start, but just in case .....

Since summer has arrived, I just recently swapped f4 / old soul.
BIG smile. (Same goes for the swap the other way round of course.)
I especially like the way old soul wakes up, all uncombed and distorted and comes to its working condition after warmup. Just like me before I got my coffee 😁
BIG smile. (Same goes for the swap the other way round of course.)
I especially like the way old soul wakes up, all uncombed and distorted and comes to its working condition after warmup. Just like me before I got my coffee 😁
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