Line stage modification
I want to change some things in one of my amplifiers.
The CD input features a non-inverting OP-AMP with a gain on 2.9***.
I want to change the IC with:
1. A discrete preamplifier
2. A better IC
I`ve found some discrete preamplifiers like this, but the first issue is the minimum load.
A more simple option, is to change the IC.
Both options will have a dedicated PSU. The default PSU is unregulated.
The Muting circuit is imperatively required ?
A drawing of the schematic.
Found an interesting preamplifier.
Look at page 9.
Have a read of Nuuk's buffer site. Particularly Pedja's
Go back to the Pass site and find the B1 buffer.
Why do you need gain on the CD input? 0dBfs~7Vac. That is far too high for any domestic power amp.
Well, as you can see in the first post, the gain is 2.9, ~ 9dB.
It is not a unity gain buffer.
Some suggestions guys ?
you have a suggestion but you seem to be ignoring it.
I aint ignoring it. I just want to improve the line stage. If this is designed with 2.9 Gain, the upgraded stage will have.... 2.9 gain.
This in fact is a OP AMP preamp, and a buffer will not suit it.
I`ve studied the B1 Buffer.
Sounds pretty neat.
If I replace the pot with a fixed resistor, the input impedance will be stuck, but what about the gain :D .
Found the AX596 line stage.
Same gain = 10db
Some thoughts ?
it is a good discrete opamp
dual complementary input with resistor bias, 22 kOhm
will perform with very low distortion
needs a regulated +-15 VDC supply, as can be seen in your image
I would add 220 Ohm EMITTER resistors into all 4 input transistors
to balance and get ~0.3 mA into each input transistor
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