Wish ya plenty of delightful hours
Just in case, when you have time - remove vertical cover and inspect condition of all small electrolytics
I didn't search for schematic, but having one would be handy, easiest way of determining are there (in that time fashionable) "Death-diodes" present
I'm not expecting thingy could give equal bliss as Papamps with VFets ( with more friendly speakers) but you certainly snatched one of the milestones ....... worth every penny
Just in case, when you have time - remove vertical cover and inspect condition of all small electrolytics
I didn't search for schematic, but having one would be handy, easiest way of determining are there (in that time fashionable) "Death-diodes" present
I'm not expecting thingy could give equal bliss as Papamps with VFets ( with more friendly speakers) but you certainly snatched one of the milestones ....... worth every penny
No schematics available, but that never stopped this grizzled technician. I have already mentally scheduled a complete inspection as per your suggestion, as a matter of insurance against the vendor's tech being less competent than he thinks he is.
When Papa comes up with a retail 100 watt VFET amplifier we can discuss comparisons. 🙂
When Papa comes up with a retail 100 watt VFET amplifier we can discuss comparisons. 🙂
counting on fact that there are just N channel Tokins available for that type of adventure, I believe that means simply too much rails (two main and few aux. ones) for Papa, to bother with
outa his sense of Elegance
though, maybe I'm wrong .......
outa his sense of Elegance
though, maybe I'm wrong .......
Luckily there are no death diodes used in this beauty. The topology is very similar to that of the Yamaha B-2 with some slight differences; IIRC the protection circuitry is the biggest difference.
There are a handful of caps and a bunch of carbon comp resistors on the PS PCB that I changed.
The amp is very well made and it's impossible to find a schematic or much other information for it.🙁
A very rare gem indeed!
Fortunately amplifier topologies don't vary much, regardless of the output devices. It's a very rare amp indeed that can't be understood by a seasoned tech. There are also a lot of Japanese hobbyists who write blogs about using SITs, so there's plenty of assistance if you know how to translate.
But you are right, as the Japanese would say, it is an "exquisite stone."
Those Tokin parts aren't really suitable for audio, they're high power switching devices. The 8000 pF input capacitance would make them useless.
I didn't know that they aren't suitable for audio. I better stop listening to my Tokin amplifiers.🙂
Oh, I'm sure if you're perverse enough you could make an amplifier out of almost anything, even a Static Induction Thyristor (return of the SITh?) but it's not a pleasant task and they won't perform well. With an 8000 pF input capacitance the Tokin SITs would be badwidth limited to hell.
I mean yeah, I've made crystal sets out of gallium chunks and bits of wire too, but it ain't what you'd call radio.
"Oh, I'm sure if you're perverse enough you could make an amplifier out of almost anything, even a Static Induction Thyristor"
I have designed an IGBT amplifier.
Sounded OK.
I have designed an IGBT amplifier.
Sounded OK.
In Tokin catalogue you can see application list with : audio amplifiers 😀
Capacitance are not big deal if Diyers use simple Papa jfets buffer at the input of the power stage,
audio frequency response bandwith are generous..
Have fun with vintage Victor..be curious and in the next step try class A audio 😉
Attachments
I would not be surprised if something close eventually appeared, even if it were just a concept. 😉
Actually there was a very good reference design in one of the semiconductor industry parts books about 25 years ago. I was going to build it but the author only allowed one pair to be built for personal evaluation, and I didn't want to go to the trouble of licencing the design if it turned out any good.
Sure, but which device are they referring to there? It's a bit hand-wavey and vague, and in any case manufacturers have a duty to tell you their parts are suitable for almost anything, just so they can sell them. The 2SK280 with a Ciss of 2500 might be usable, but it would still be an almighty compromise. Let's face it, the Tokin parts are very industrial.
Well that was a bit condescending, not that there's anything wrong with that. The Victor amp does operate in push-pull Class A in part of it's range, from 10 to about 50 watts output. But I gather you meant "single-ended power-wasting constant-heat-producing Class A" which I personally see as a bit of a misuse of good parts that could be employed more effectively.
I gave up single-ended Class A when I stopped making 807 amplifiers out of old WWII transmitters in 1969. Some people just take longer to learn I guess, or maybe people from the colder parts of the northern hemisphere simply don't see the extra room warmth generated (and corresponding power bills) as a downside.
don't be so exclusive
besides well known fact that there are around several different amps made with elevator thingies produced by Tokin, you can also take a lookl at partial data of Holly Grail of them all - 2SK77B, short-lived and ultra rare successor of 2SK77 - pdf attached
matter of drive, nothing else
I mean, if easiness of drive and benign character of output part is sole criteria of part usability, nobody would ever try to make an amp with VT4C, let alone 845....
I mean, subject is broad ........ thus generalization more often leads to sayin' nuttin', instead of sayin' summtin'
I just popped on to Ebay to have a look, and there is a fair amount of Victor gear up for sale, though it's hard to tell if any of the things up for auction use SITs rather than conventional bipolar or mosfet devices. The integrated amps look tasty, and remind me of a 70's era Kenwood integrated amp on steroids.
An arm, leg, and testicle for $1500 au ? Victor JM-S7 stereo V-FET power amplifier. | Stereo Systems | Gumtree Australia Marion Area - Hallett Cove | 1222165774
Economy must be rough down under 😀
Economy must be rough down under 😀