Interesting thread, I was reminded by an old amp build that I made based on AKAI design. The schematic was traced by an old mentor from the original board, I drafted it in CADware. I do remember that I made some resistor values in the bias circuit because I was using newer devices, (and yes one terminal of the trimpot is left hanging in the pcb) for a low power amp SQ is very good. (Astron was a local manufacturer/distributor.)
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I suspect it is a part of a tone control network, by design older models (Japanese?) had the tone control integrated into the feedback loop. The original pcb had them installed as part of the whole amp and not on a separate board. BTW the schematic is as is with the original pcb. It is not a moded/revised design. ( I put the rev extension in the file name and the "clone" word in the schematic as a personal marking/signature).
AKSA 55 used different paths for AC & DC feed Back.
I tried it. If we made high input impedance in BJT's LTP input, it will forced us to use high resistance DC feedback. It made DC offset low. But I found it is better to use low resistance feedback.
The schematic above (post #182). The story goes, at the time that I was still visiting my old mentor at his shop, he let me carry some of his units to audition at home and see its innards. He wanted me to experience the wonders of vintage hi-fi. I could not recall the exact models but mostly they are of Japanese origin, Onkyo, Sansui, Technics, Toshiba and Pioneer. Most runs at decent power of about 60-100w and housed with large chassis.
He has convinced me that these amps had pretty good sonic details that is quite pronounced at lower volume level and that which makes them very good amps for home.
Guys,
I was doing a sim run of a vintage bootstrapped amp [Toshiba Aurex SB-A50], I was trying to apply the currently existing transistor models in an attempt to replace the non-available one's. I was able to come up with the ref voltages closer to that of the original one [not so sure 'bout currents though] However in the course between sim runs the pace becomes to that of a walking man
It used to be a sprinting man.
Attached the spice files, can you guys have it run on your pc's to see whether the problem is with my pc resources? My LTSpice program is actually core affinited and have a 100% CPU responsiveness with 72% ram consumption.
Sa muli,
Albert
I was doing a sim run of a vintage bootstrapped amp [Toshiba Aurex SB-A50], I was trying to apply the currently existing transistor models in an attempt to replace the non-available one's. I was able to come up with the ref voltages closer to that of the original one [not so sure 'bout currents though] However in the course between sim runs the pace becomes to that of a walking man
It used to be a sprinting man. Attached the spice files, can you guys have it run on your pc's to see whether the problem is with my pc resources? My LTSpice program is actually core affinited and have a 100% CPU responsiveness with 72% ram consumption.
Sa muli,
Albert
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It seems not to be a fault with your PC...
As you asked for help and curiosity got the better of me I thought I'd check for you.
Good luck with optimising it...
Guys,
I was doing a sim run of a vintage bootstrapped amp [Toshiba Aurex SB-A50], I was trying to apply the currently existing transistor models in an attempt to replace the non-available one's. I was able to come up with the ref voltages closer to that of the original one [not so sure 'bout currents though] However in the course between sim runs the pace becomes to that of a walking man
Attached the spice files, can you guys have it run on your pc's to see whether the problem is with my pc resources? My LTSpice program is actually core affinited and have a 100% CPU responsiveness with 72% ram consumption.
Sa muli,
Albert
As you asked for help and curiosity got the better of me I thought I'd check for you.
Good luck with optimising it...
back to the sprinting man.. 
...umm guys what is wrong with the square wave,? I was only feeding 1khz of freq, result seemed to suggest a huge cut in high-freq roll off. I was simplifying the circuit, drop the + rail voltage regulator and the input current mirror.to see the effect but still the same result was shown by LTSpice.
Sa muli,
Albert
Sa muli,
Albert
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de Ocampo,
Asymmetric slew rate? I don't sure (since I don't cannot read the included schematic), but maybe can a LTP unbalance or higher than desired Cdom or "other compensation capacitor", although this probably provoke more symmetric slew-rate limiting.
Other friends here perhaps note something else that I don't see now.
Asymmetric slew rate? I don't sure (since I don't cannot read the included schematic), but maybe can a LTP unbalance or higher than desired Cdom or "other compensation capacitor", although this probably provoke more symmetric slew-rate limiting.
Other friends here perhaps note something else that I don't see now.
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