To obtening more power from this ampli can i use 2 braces of output BJT? (the BJT are Sanken 2SA1295/2SC3264)
With 85v power supplies can i have about 200w into 4 ohm?
For the amp being able to handle the needed current for 4 Ohms load, I would advise you to use at least 3 extra of each output devices pr. channel (and personally I would also add an extra common driver stage to drive to output devices).
And while you're at it, use a dual rail power supply. Get rid of C6, R21 and R2. Connect R24, R3, C2, C3, C5 and speaker to 0V instead of the negative rail.
When you specify an 85V power supply, may I assume you are choosing a transformer VA rating consistent with the proposed 4 ohm load?
sam9 said:
I use this amplifier with an smps.
The smps have an output of 85v @ 15A for each channel!!!
Inserting a resistor ( of the order of 100 R ) between the emitters
of Q7 and Q8 and paralleling that resistor with a capacitor ( of the
order of 1 u ) might be beneficial for the switch off performance
of the output transistors.
By the way, more power in amplifiers is only useful upto a certain ( not so high ) limit. A few clean watts is all that we need.
Best Regards
Selim
of Q7 and Q8 and paralleling that resistor with a capacitor ( of the
order of 1 u ) might be beneficial for the switch off performance
of the output transistors.
By the way, more power in amplifiers is only useful upto a certain ( not so high ) limit. A few clean watts is all that we need.
Best Regards
Selim
Above a certain power level, it is recommended to cascode a BJT output stage for reliability. This depends on the safe operating area of the output transistors, but as a rule using more than about +-60v supplies requires cascoding the outputs for reliability. This was figured out in the early 70s with high powered amp designs -- feel free to tempt fate, but you will be sorry. If you wish to use 85v rails, it is virtually mandatory to cascode bipolar outputs.
The Leach SuperAmp is an online example of an excellent proven output stage design in this power class.
http://users.ece.gatech.edu/mleach/superamp/
Note that this design requires 8 bipolar output transistors per amp. Because Mosfets do not need to be cascoded, they allow the use of fewer output devices per channel (4-6), but they cost more per device.
The Leach SuperAmp is an online example of an excellent proven output stage design in this power class.
http://users.ece.gatech.edu/mleach/superamp/
Note that this design requires 8 bipolar output transistors per amp. Because Mosfets do not need to be cascoded, they allow the use of fewer output devices per channel (4-6), but they cost more per device.
Thanke you!!!🙂
And about this amplifiers woth do you think:
This ampli with 2 pair of power BJT (Sanken 2SA1295/2SC)!
The tube V3-V4 is not used beacouse are the pre-amplifiers that i don't use!!
And about this amplifiers woth do you think:
This ampli with 2 pair of power BJT (Sanken 2SA1295/2SC)!
The tube V3-V4 is not used beacouse are the pre-amplifiers that i don't use!!
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