[78-L] EQ ideas for transferring acoustic 78s?

[David Lennick]

On 4/25/2011 11:54 AM, Ken Matheson wrote:
>
>
> But also other power line frequencies will creep in to a recording.
> 180 cycles (Hz.), for 3 phase power, or 150 in the case Western Japan.
> I have never run across 400 or 1200 cycles in a recording but I know
> it is used in some portable or mobile power equipment.
>
> Some electrical recordings will have this problem also.
>
> Ken

Early London lps sometimes have a roar at somewhere around 150hz. Any idea what 
causes this? The chip vacuum, maybe?

dl