The main application of this unity gain buffer device is the reducing of harsh and crispy sound character of various cd players resp. D/A converters.
My idea is now to use this device as a unity gain pre-amp for driving long signal cables to mono power amplifier inputs.
The retrofit of a good potentiometer shouldn't be an issue.
The question is, what is the aim of the serial input capacitor which have only 22pF.
In the attachment the description of the whole project include schematics.
My idea is now to use this device as a unity gain pre-amp for driving long signal cables to mono power amplifier inputs.
The retrofit of a good potentiometer shouldn't be an issue.
The question is, what is the aim of the serial input capacitor which have only 22pF.
In the attachment the description of the whole project include schematics.
C1 is 2.2 µF.
The circuit does not seem the best solution to drive long cables and it lacks power on/off muting. It also filters and was clearly designed for another purpose and for devices way back. You very likely don't need the filtering when using a decent DAC equipped with a good output stage. What is the input impedance of the power amplifier?
ECC1656 can be a good choice too. 2 Coupling caps less to worry about. Excellent drive capability.
The circuit does not seem the best solution to drive long cables and it lacks power on/off muting. It also filters and was clearly designed for another purpose and for devices way back. You very likely don't need the filtering when using a decent DAC equipped with a good output stage. What is the input impedance of the power amplifier?
ECC1656 can be a good choice too. 2 Coupling caps less to worry about. Excellent drive capability.
Last edited:
Thank you for that advice - concerning the input capacitor the part list show right value and in the schematic "22p" is a misprint.
Input impedance is according the schematic 1M5.
Please consider OPA1656 as buffer (output to inverting pin so a gain of 1) to drive longer cables. It does not glow but it sounds excellent. It takes an open mind to try this but till now I haven’t heard anything negative even from tube fundamentalists. As bonus you can make that 1M5 the standard 10 kOhm and have lower noise.
IMHO anything that is inserted should have as least negative side effects as possible. No added noise, hum or distortion. OPA1656 is such a solution.
IMHO anything that is inserted should have as least negative side effects as possible. No added noise, hum or distortion. OPA1656 is such a solution.
Last edited: