On 2015-04-27 8:45 PM, Paul Stamler wrote:
> On 4/27/2015 2:05 PM, John Haley wrote:
 >> Turntables from the 78 era are usually nightmares
>> for rumble, instability, etc.
>
> A big amen to that. Incidentally, a disc meant to play at 80rpm will, if
> played at 78.25rpm (nominal "78" speed) come out with every frequency at
> 0.978125 x what was intended.
>
> Sincea note that's a semitone flat is 0.9439 x the intended frequency,
> that means that an 80rpm disc played at 78.25rpm will be less than a
> semitone off. Still worth correcting. If the frequencies are all
> multiplied by 80/78.125 = 1.0223642, they'll come out right.
>

Hi, Paul and John,

The list has made an assumption that this was a 78-era turntable, based 
on, I think, that the OP said "only does 78 RPM." One turntable that 
might fill this bill in this context is the Technics SP-10...one of 
which I am resurrecting for a better playback system (with a short SME arm).

Anyway, in the 78 RPM context, the SP-10 "only does 78" because 33 and 
45 are irrelevant to the discussion. The BBC version had varispeed, but 
I don't think that was ever sold in North America.

With all that said, I'm really posting to urge that if fine speed 
changes are going to be made in software that the user make certain to 
use the RESAMPLE mode (which is akin to the varispeed knob) as all the 
other speed/pitch change algorithms which change the two factors 
independently are much more artifact prone.

Also, I wanted to remind the OP that the transfers really have to be 
done at 96/24 or higher if one is going to speed-shift in the DAW.

Of course 96 is also good for accurately reproducing the scratches to 
make removal easier.

Cheers,

Richard
-- 
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada                             647 479 2800
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.