What would be the minimun +-DC voltage require to guaranteed 200W/channel out-put?
@Mikewong,
I did not design this layout having a 200W amplifier in my mind.
The TO3-transistors are screwed on small ALU-L profiles, and I doubt that these profiles will be able to conduct the heat that you will produce.
If you pursue your ideas, you should at least mount the TO3-transistors directly on a big heatsink.
Best regards - Rudi_Ratlos
I did not design this layout having a 200W amplifier in my mind.
The TO3-transistors are screwed on small ALU-L profiles, and I doubt that these profiles will be able to conduct the heat that you will produce.
If you pursue your ideas, you should at least mount the TO3-transistors directly on a big heatsink.
Best regards - Rudi_Ratlos
That`s what I am going to do.I got two big heatsinks for this project.
I am not expert here,but I do know that power increase with higher supply voltage,provided that all is done within the limits of the components.
Have a good look at the components on the symasym schematic and decide if you can ensure none will burn up by adopting a 200W into 8r0 PSU.
Then, have another good look and decide if you can guesstimate the new working point currents for the High Voltage PSU operation.
The Lo Tim is designed for a 40Vac transformer. The Symasym is not !!
Then, have another good look and decide if you can guesstimate the new working point currents for the High Voltage PSU operation.
The Lo Tim is designed for a 40Vac transformer. The Symasym is not !!
Andrew, Pinkmouse,
in my layout I have extended the the original schematics of the SYMASYM by a cap multiplier:
that does not only smoothen the voltage for the frontend, but also separates the frontend voltage from the backend voltage
by means of the Zener diode D1. The SYMASYM needs < 10mA current for the frontend on both rails.
The CAP-multiplier can be disabled by means of a jumper.
Theoretically MikeWong can pursue his ideas, but he must take very much care about heat convection.
Best regards - Rudi_Ratlos
in my layout I have extended the the original schematics of the SYMASYM by a cap multiplier:
that does not only smoothen the voltage for the frontend, but also separates the frontend voltage from the backend voltage
by means of the Zener diode D1. The SYMASYM needs < 10mA current for the frontend on both rails.
The CAP-multiplier can be disabled by means of a jumper.
Theoretically MikeWong can pursue his ideas, but he must take very much care about heat convection.
Best regards - Rudi_Ratlos
Last edited:
If one eliminates R19 and its negative rail homologue, one could feed the cap multiplier from a higher voltage via the jumper. It is also easy to convert it to a simple regulator.
Doing this way, the voltage swing of the VAS will be higher and this will increase output stage efficiency.
The auxiliary voltage can be obtained from the same transformer windings that feed the output stage.
Doing this way, the voltage swing of the VAS will be higher and this will increase output stage efficiency.
The auxiliary voltage can be obtained from the same transformer windings that feed the output stage.
Franz,
the frontend of the SYMASYM needs < 10mA current.
The voltage drop over R19 is about 200mV then. I kept this resistor, in case somebody wants to build
the "original SYMASYM", without any modification.
But I know from several DIYers, who operate their SYMASYM from 30VAC transformers and who use 39V
Zener diodes to delimit the frontend-voltage to < 40VDC and thus protect the input transistors (2SK170).
Best regards - Rudi_Ratlos
the frontend of the SYMASYM needs < 10mA current.
The voltage drop over R19 is about 200mV then. I kept this resistor, in case somebody wants to build
the "original SYMASYM", without any modification.
But I know from several DIYers, who operate their SYMASYM from 30VAC transformers and who use 39V
Zener diodes to delimit the frontend-voltage to < 40VDC and thus protect the input transistors (2SK170).
Best regards - Rudi_Ratlos
Thanks for the input Andrew.
Just to clarify things, I have all these transistors already... so I won't be spending any money for them. Is the bias transistor not suitable for sysmasym? I have a few of them and I like the fact that the capsule is full plastic, no metal side.
I want to use the best components I have in my inventory for sysmasym mainly because this might be the last amplifier I build and the rest of the stuff will never be used. Donated a lot of components already, more to go soon!
Cheers,
Vlad
Just to clarify things, I have all these transistors already... so I won't be spending any money for them. Is the bias transistor not suitable for sysmasym? I have a few of them and I like the fact that the capsule is full plastic, no metal side.
I want to use the best components I have in my inventory for sysmasym mainly because this might be the last amplifier I build and the rest of the stuff will never be used. Donated a lot of components already, more to go soon!
Cheers,
Vlad
Vlad,
this is the arrangement / placement of the TO3-transistors on the ALU-L profile:
How will you ever be able to mount MT200 cases instead of the TO3s on the ALU-profile?
On the other side: if you really own a couple of authentic SANKEN 2SA1216 / 2SC2922, I am sure that you will be able to sell them
in the "Swap Meet" forum in a very short time for a fair price.
Go for the TO3s - please.
Best regards - Rudi
this is the arrangement / placement of the TO3-transistors on the ALU-L profile:
How will you ever be able to mount MT200 cases instead of the TO3s on the ALU-profile?
On the other side: if you really own a couple of authentic SANKEN 2SA1216 / 2SC2922, I am sure that you will be able to sell them
in the "Swap Meet" forum in a very short time for a fair price.
Go for the TO3s - please.
Best regards - Rudi
