Relevant Part of TPA-3006. The only I have...
The image size imposed by this forum is a great communication obstacle and a real pain.
The time I lose trying to compress is very discouraging…
🙁
The image size imposed by this forum is a great communication obstacle and a real pain.
The time I lose trying to compress is very discouraging…
🙁
The missing information:
Wire marked 0V is the output line.
Q230//Q231 are the drivers of two pairs of S-follower 2SK175/2SJ55 with 680ohm gate resistor(2SK) and 390ohm gate(2SJ).
Looks like a kind of Hawksford EC ...
Wire marked 0V is the output line.
Q230//Q231 are the drivers of two pairs of S-follower 2SK175/2SJ55 with 680ohm gate resistor(2SK) and 390ohm gate(2SJ).
Looks like a kind of Hawksford EC ...
Locks like they take of components, one by one from Bob circuit, at the point it stops to work.
Than they have putted the last one again in their place.
Than they have putted the last one again in their place.
mikeks said:
Thanks for the tip.
I think I will try get the Meyer Sound MS1000 schematics instead then. Bob mentions this amp up north somewhere.
Maybe later tandberg amplifiers had better EC system. Am waiting for a new workbench to be fitted and will start knocking some circuits up.
Kevin
Good one,
remarkably well for a low bias mosfet amp in those years, i did not understand why untill i read Mr Cordell's paper. The high priced TPA-3016A out-tricked a P-300V in the late 80s, imho.
A big Hitachi TO3 Mosfet amp like a Perreaux PMF series did not give me the shivers either, but the Hot Kiwi output stage operated at a high class A level, up to 25-30W (fttomh)
(naturally my preference was for the equally expensive Threshold SA/3, me don't need no 200 watts)
remarkably well for a low bias mosfet amp in those years, i did not understand why untill i read Mr Cordell's paper. The high priced TPA-3016A out-tricked a P-300V in the late 80s, imho.
A big Hitachi TO3 Mosfet amp like a Perreaux PMF series did not give me the shivers either, but the Hot Kiwi output stage operated at a high class A level, up to 25-30W (fttomh)
(naturally my preference was for the equally expensive Threshold SA/3, me don't need no 200 watts)
Mikeks,
---Has anyone got a copy of the Tandberg schematic?---
In case of need : there was a short article published in Electronics World where a Cherry's scheme, one of the first John Curl's amplifier and a Tandberg Error Correction scheme were shown. I can provide a copy.
---Has anyone got a copy of the Tandberg schematic?---
In case of need : there was a short article published in Electronics World where a Cherry's scheme, one of the first John Curl's amplifier and a Tandberg Error Correction scheme were shown. I can provide a copy.
TOINO said:
This is probably a decent implementation of HEC, but I think it would perform better if the VAS was buffered from the HEC circuit. Also notice that the collector of the EF that follows the HEC summing node (Q224/Q225) is not bootstrapped to signal, but returned to the power supply, so it must be a HV transistor and its ccb will create some nonlinearity. Nice that they regulate the rails to the input and driver circuits, and nice that they cascode the VAS.
Cheers,
Bob
Just a small curiosity:
Believing in this information here http://www.nrhf.no/t-TPA-3006A.html the amplifier is from 1984 which is the publication year of Mr. Cordell paper on AES http://www.cordellaudio.com/poweramp/mosfet.shtml 😉
Believing in this information here http://www.nrhf.no/t-TPA-3006A.html the amplifier is from 1984 which is the publication year of Mr. Cordell paper on AES http://www.cordellaudio.com/poweramp/mosfet.shtml 😉
Bob Cordell said:
On the contrary, because it relies on resistively loading down the transimpedance stage for correct operation, this is a sub-optimal implementation.