They are linear at will...
Using two separate devices of very good quality
and then CONNECTING TWO RESISTORS from
bases to ground of each devices before mesuring
the HFE would precisely display that kind of curves....
The devices i mentionned are between this one and the
1647 in matter of Pd and Ic.
Their datasheet can be find at Datasheetcatalog.com
They were marked as product dedicated to a single
constructor, Pioneer.
With time, they had became mass market devices
with their original marking.
It really is the http://www.diyaudio.com/forums/solid-state/111756-rmi-fc100-single-stage-audio-power-amplifier.html
RMI-FC100 by Roender.They drew it different , that is why I did not call it a clone originally. (who knows, maybe it was the other way around??) Mistake 1 , change bottom fixed VAS cascode to a wilson CM , good to go.... simulates REAL good.
I think the chinese pilfered Roender's design , they just use a different current source scheme.(FET CCS)
(one that works is below)
OS
Attachments
That is "pickyune" , you can omit OPS GNF with ANY amplifier.Take NFB from a voltage stage or the drivers , I do it for HF all the time. NFB takeoff is a personal design option . The "chinese" amp takes it from the Voltage stage .. so it has overall NF , just not from the OPS.
BUT, the "core" is all RMI. Depending on the date of that chinese schema , either Roender cloned it , or they cloned his .... or neither. Independent engineering on different sides of the planet ????
OS
All J-fet current source are drown in a wrong way and there is a resistor surplus at vas collector output, right?
I think you are all wrong.
The oldest schematics Ive seen using this type of voltage amp comes from Luxman, yep from Japan. As far as I can see it looks like it even predates Scott Wurcher and AD. According to AD, Scott Wurcher first opamp, the AD524 dates from 1982, the AD797 came later and by this time luxman already had various models in production using this topology, oldest luxman reference is from 1980 , so I guess this is where scott got the idea from. The ad797 does have some improvements on the original design though. Im not sure who designed the Luxman amps, some say Tim de Paravicini, but I doubt this as he was a tubes guy.
Roenders RMI amp is basically a copy of a Luxman L5...., I cant remember the exact model number but the voltage amp section is virtually identical, only that the RMI came some 28 years later. Luxman has various model amp and preamps based on this topology with small mods, like a changes in current sources which is the case with roenders amp and the amp shown in this thread as well.
BTW it is interesting to note that Luxman as far as I can see is also the first to use what is now called Hawksford cascodes.
The oldest schematics Ive seen using this type of voltage amp comes from Luxman, yep from Japan. As far as I can see it looks like it even predates Scott Wurcher and AD. According to AD, Scott Wurcher first opamp, the AD524 dates from 1982, the AD797 came later and by this time luxman already had various models in production using this topology, oldest luxman reference is from 1980 , so I guess this is where scott got the idea from. The ad797 does have some improvements on the original design though. Im not sure who designed the Luxman amps, some say Tim de Paravicini, but I doubt this as he was a tubes guy.
Roenders RMI amp is basically a copy of a Luxman L5...., I cant remember the exact model number but the voltage amp section is virtually identical, only that the RMI came some 28 years later. Luxman has various model amp and preamps based on this topology with small mods, like a changes in current sources which is the case with roenders amp and the amp shown in this thread as well.
BTW it is interesting to note that Luxman as far as I can see is also the first to use what is now called Hawksford cascodes.
Thanks John, I wondered about the Harris opamps, I never managed to find dates when they were designed or produced. Did Harris or anyone else patent it ??
Do you know who did the original design of the Hawksford cascode perhaps ??? Im stuck here to a design by Luxman as well, dating to 1979 ???
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