"geoff" wrote in message


Dave W. wrote:

If, as you say, the signal is clean, then as long as you
have it digitised there is no problem.

But what is digitized? Is it really a pure signal, or is there a noise floor
that can intrude on the faint signal coming into the RIAA preamp? A MC
preamp or transformer raises the signal above the noise floor of the MM
preamp. Since there is currently no MC preamp or transformer, the noise
floor of the MM preamp is probably the weakest link.

Before saving it
to any 'lossy' compression method, simply amplify it in
Audacity. This is a mathematical operation, and the
'clean signal' will be end up being as loud as you want
it to be.

Problem here is that there's always an analog domain noise floor, if only in
the existing analog-to-digital converter. In this case I expect that the MM
RIAA preamp is the weakest link. I base this on many experiences with them.
Even with 16 bit converters, a MM RIAA preamp is the weakest link.

Let me give a real world numerical example. If I adjust a good MM RIAA
preamp so that the preamp clips at a slightly higher level than a
high-trackability cartridge mistracks on a test record, the needle-up noise
floor will be 70+/- dB down. Since the noise floor of a good 16 bit
converter is more like 96 dB down, the weakest link is the MM RIAA preamp.

However as you amplify it, yo will also bring up the
quantisation noise. It is best to optimise your recording
level first.

Agreed. And that's why there are such things as MC pre-preamps and
transformers.

The effect can be reduced by ensuring you are recording
at 24 bits resolution.

A 24 bit converter does no more good - it just gives a higher resolution
rendition of the noise in the MM RIAA preamp.