I stumbled across the following phono amp from the 30s, prior to the RIAA standard which was written in the 50s. When there was no standard for compression it was apparently desirable to be able to adjust expansion.
http://www.one-electron.com/Archive... 6L7 as a Volume Expander for Phonographs.pdf
I thought that when one is being social and the music is in the background it would be desirable to reduce expansion so that soft passages could be heard over conversation without the loud passages preventing conversation.
Do any of you have experience with variable expansion and have any recommendations or alternative circuits?
http://www.one-electron.com/Archive... 6L7 as a Volume Expander for Phonographs.pdf
I thought that when one is being social and the music is in the background it would be desirable to reduce expansion so that soft passages could be heard over conversation without the loud passages preventing conversation.
Do any of you have experience with variable expansion and have any recommendations or alternative circuits?
It appears that this only expands, but does not compress. A true loudness control would be better
in general for low volume listening than a compressor, though.
in general for low volume listening than a compressor, though.
Yes, the circuit only expands, but as the recording on the vinyl is already compressed a reduction in expansion is in relative terms, compression. Still, a loudness control might be preferable. Do you recommend one?
Few recent preamps have a true loudness control, but you could look up some older circuits.
Tube or transistor? Op amps would be the easiest way to build one.
Do you have tone controls in the amplifier? If you experiment around with the bass control,
that will give you some idea of how well a loudness control would work, at a specific low volume.
Tube or transistor? Op amps would be the easiest way to build one.
Do you have tone controls in the amplifier? If you experiment around with the bass control,
that will give you some idea of how well a loudness control would work, at a specific low volume.
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The plan is for this phono-amp to feed an old Marantz pre-amp, which is followed by a 6L6 power amp into Klipsch corner horns. So Marantz provides some tone control.
My day-job is current-tech, so as a hobby I only use tubes; no transistors.
My day-job is current-tech, so as a hobby I only use tubes; no transistors.
