Hello. i want to use higher voltage rail on this preamp,about 35V. what changes do i have to do in parts?
the whole article IS HERE : http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1970/Tone-balance Control DCD.pdf
the whole article IS HERE : http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1970/Tone-balance Control DCD.pdf
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What currents pass through your devices?
What voltage appears across each device?
Multiply I & V to determine Pq for every device.
Now change to your new supply voltage.
Repeat the Pq determination exercise.
What voltage appears across each device?
Multiply I & V to determine Pq for every device.
Now change to your new supply voltage.
Repeat the Pq determination exercise.
You can't simply increase supply voltage by such a large amount without a redesign, addressing DC and AC conditions. It is likely that the value of most resistors would have to change.
Its just as bad a performer on 35 volts as on 12. All you need change is R22 to 2.2k and select a value of R 21 so that you get around 17 volts on the emitter of Q9. The value is dependent on transistor gain.
Its just an inverting buffer with poor drive ability.
Its just an inverting buffer with poor drive ability.
ok. thanks i understand.. can you suggest a transistor inverting amplifier to implement the tilt equaliser i posted above? i have built it using opa2134 in the past but now i want to build it using descrete parts to compare the two of them.
An externally hosted image should be here but it was not working when we last tested it.
Why?
There is little point in comparing low quality amps, or a low quality amp with a high quality amp. To compare two high quality amps you don't put them in a circuit with 100% feedback, as the feedback washes out almost all the variation in performance.
There is little point in comparing low quality amps, or a low quality amp with a high quality amp. To compare two high quality amps you don't put them in a circuit with 100% feedback, as the feedback washes out almost all the variation in performance.
I can't just think of any suitable discrete buffer tbh. The opamp is ideally suited for that circuit and a FET opamp allows direct connection of the wiper as shown. The discrete circuit has the input "floating" at whatever voltage the emitter of the second transistor is at (via those 47k's). Sonically it should be totally transparent in the centre position.
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