I have just acquired a Technics SL-PD687 5 disc changer. As it is a changer and thus probably not a very good transport (in other words, maybe not worth a lot of time and expense modding), I am looking for advice on relatively inexpensive, best-bang-for-your-buck type modifications.
The output opamp is a 4558, and seems to be driven by low rails, so not much promise there.
There is a connector between the control/power board and the transport board which provides a convenient tie-in point, as it appears to have the unamplified audio outputs as well as the I2S bus (pinout goes L,GND,+5V,BCLK,LRCK,SRDATA,GND,...).
One question, if I were to take the low-level audio signals at this connector (I believe it is already a voltage output), and just run some wire to the back panel in order to build an outboard opamp stage to boost to line level, would this work OK, or would the low-level signal just pick up a ton of noise?
Another, are changers worth the effort in your opinion, or do they always fall short of a single transport in performance?
The output opamp is a 4558, and seems to be driven by low rails, so not much promise there.
There is a connector between the control/power board and the transport board which provides a convenient tie-in point, as it appears to have the unamplified audio outputs as well as the I2S bus (pinout goes L,GND,+5V,BCLK,LRCK,SRDATA,GND,...).
One question, if I were to take the low-level audio signals at this connector (I believe it is already a voltage output), and just run some wire to the back panel in order to build an outboard opamp stage to boost to line level, would this work OK, or would the low-level signal just pick up a ton of noise?
Another, are changers worth the effort in your opinion, or do they always fall short of a single transport in performance?
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