Revisiting some "old" ideas from 1970's - IPS, OPS - Page 2 - diyAudio
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Old 15th July 2015, 10:04 PM   #11
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Quote:
Originally Posted by moschfet View Post
Hi Val,
very interesting, like all of yours
..but look at the supply voltage of the LF411.
Ahhh... this is definitely a "typo"
Thanks for pointing out!

Corrected
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File Type: jpg @DC2-Sch-01.JPG (167.4 KB, 965 views)
Attached Files
File Type: pdf @DC2-Sch-01.pdf (64.8 KB, 71 views)
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Old 15th July 2015, 10:05 PM   #12
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Quote:
Originally Posted by ostripper View Post
Yup , I'll individually simulate OPS/IPS. Combine either with various other
IPS/OPS's , see whether both are "universal".

Edit - we won't let em' get "bored".
OS
Sure we won't
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Old 15th July 2015, 10:06 PM   #13
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Quote:
Originally Posted by jwilhelm View Post
2SK170 is getting harder to find in North America. The DIYAudio store is cleaned out of them too. I have a couple left though.
2SK117 will work perfectly there as well - just in case...
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Old 19th July 2015, 09:33 AM   #14
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Arrow Searching for "purity" :)

Tried to simplify the front-end, sticking to the same principle and preserving the quality.

These two options - having single end VAS with CCS (1) and bootstrapped R (2) loads - utilize just one Complementary Differential Circuit (CDC) and use BJT transistors only, nothing difficult to find.
Choose the one you like

Both offer harmonics at -100db level in audio bandwidth, low TIM and rather high speed. Distributed compensation is pretty light. Local feedbacks keep the circuit rather linear even open-loop - around 0.1% THD @ 20KHz, 20V RMS, 80db gain.

Attached AC analysis is done with a simple EF3 OPS attached. I keep VAS rather warm (15mA), so MOSFETS (Lateral or Hex-FET) can be driven directly from it with no problem.

If somebody wants to "practice" PCB development - you are welcome
Can be SMD or TH or a combination of both.

Cheers,
Valery

P.S. This circuit can be also used as a high-end pre-amp line gain stage (rails can be lowered for that purpose, like +/- 24V, with couple of resistor values amended), or an excellent amp for the headphones - with optional addition of a single push-pull EF (MJE340/350) - at the same +/-24V rails.
Attached Images
File Type: jpg @01-CDC-CCS-Sch.JPG (114.9 KB, 951 views)
File Type: jpg @02-CDC-Boot-Sch.JPG (111.3 KB, 900 views)
File Type: jpg CDC-VFA AC Analysis.JPG (80.2 KB, 853 views)
Attached Files
File Type: pdf 01-CDC-CCS-Sch.pdf (42.8 KB, 65 views)
File Type: pdf 02-CDC-Boot-Sch.pdf (42.2 KB, 57 views)
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Old 22nd July 2015, 11:21 AM   #15
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Here's the SMD version of the CDC-VFA-CCS.
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File Type: png CDC-VFA-CCS.PNG (81.6 KB, 766 views)
File Type: png CFA-VFA-CCS board.PNG (42.5 KB, 262 views)
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Old 22nd July 2015, 12:54 PM   #16
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Quote:
Originally Posted by vzaichenko View Post
Tried to simplify the front-end, sticking to the same principle and preserving the quality.

These two options - having single end VAS with CCS (1) and bootstrapped R (2) loads - utilize just one Complementary Differential Circuit (CDC) and use BJT transistors only, nothing difficult to find.
Choose the one you like

Both offer harmonics at -100db level in audio bandwidth, low TIM and rather high speed. Distributed compensation is pretty light. Local feedbacks keep the circuit rather linear even open-loop - around 0.1% THD @ 20KHz, 20V RMS, 80db gain.

Attached AC analysis is done with a simple EF3 OPS attached. I keep VAS rather warm (15mA), so MOSFETS (Lateral or Hex-FET) can be driven directly from it with no problem.

If somebody wants to "practice" PCB development - you are welcome
Can be SMD or TH or a combination of both.

Cheers,
Valery

P.S. This circuit can be also used as a high-end pre-amp line gain stage (rails can be lowered for that purpose, like +/- 24V, with couple of resistor values amended), or an excellent amp for the headphones - with optional addition of a single push-pull EF (MJE340/350) - at the same +/-24V rails.
You have 5 comp. caps ? Lead /lag , miller , and a shunt ! How did you arrive at these ?

BTW , a very interesting "blameless" -mutant. I like the decoupled low voltage input and overload clamp.

OS
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Old 22nd July 2015, 05:14 PM   #17
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Funny that we have to look back to the 70's to find really good amps. I'd say that is because stereos "mattered" back then. Having a great stereo was a status symbol and folks were willing to pay good money to impress their friends. Today they need to stuff 6 channels into a small box that will fit on a shelf under their flat screen.

How I remember going to the audio store and listening to Emerson, Lake and Palmer through a huge set of speakers and monster amps. Bass you could feel and mids and highs that seemed to come from every corner of the room. The store was filled with young men dreaming of owning that perfect "system". Those were the days! Great memories.
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Old 22nd July 2015, 05:22 PM   #18
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At least 2 or 3 Hi-fi shops in every city, I remember them days too. Nowadays it is pods or something that young people want and a smart phone that everyone carries in there hand, not pocket. I saw a wreck on the interstate a few years back where the SUV rolled a few times with the lady thrown out the window during some flips and guess what was still in her hand when she landed? There is still a market for hi end 2 channel but the market is a lot smaller.
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Old 22nd July 2015, 05:32 PM   #19
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Quote:
Originally Posted by still4given View Post
. Bass you could feel and mids and highs that seemed to come from every corner of the room. The store was filled with young men dreaming of owning that perfect "system".
no longer so "young" these days.
At least the system is currently @ 90% of those younger dreams.
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Old 22nd July 2015, 06:06 PM   #20
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Watch sometime who is driving that "dream" hot rod. He'll have a few gray hairs. He finally got one. Whenever I listen my big JBL's through the Slewmaster or one of Valery's creations I think, "If my friends could see me know".

My younger brother just brought me a ZZ Top vinyl the other day. I'm going to have to dust off the SL-1200-MK2 and give it a spin. That is going to bring back some memories.
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