Hi, Louis,

This is a complex question. While I do not attempt speed changes for 
grooved media, I do it often for magnetic media, especially those 
horrific "rim drive" reel or cassette machines where the speed was never 
constant.

With that said, I suspect that every DAW is different. I have a bit of 
experience with my main DAW, Samplitude, and a small amount of 
experience with the Diamond Cut series of programs for this function.

Samplitude always had a linear speed-correct function, where one could 
change the speed, pitch, or both a constant amount for the duration. It 
was only in the later versions that they produced the capability of 
making a "ramp" or a "speed profile".

The options are:
Resample
Standard
Beat Marker Stretching (smooth)
Smooth
Beat Marker Splicing
Beat Marker Stretching
Monophonic Voice
Universal HQ

The ONLY one that mimics the varispeed knob on an analog machine is 
Resample. In this mode the speed and pitch knobs are reciprocally 
interlocked, as you would expect and it is the only one to proceed 
without horrid artifacts. If I am going to vari-speed something I try to 
start with a 96 ks/s transfer because if you have to slow something down 
and you only have 44.1 ks/s and you cut the speed by 1/2, you end up 
with effectively 22.05 ks/s.

In Samplitude select Resample prior to invoking "Elastic Audio" if you 
need a speed profile or other non-constant adjustment.

In Diamond Cut, their speed adjustment (from the earliest version I had) 
included a start and end speed and then the ability to hinge a series of 
curves to approximate the speed trajectory. I believe this, too, 
resampled and sounded reasonably good, but I just don't use the product 
in my work flow anymore.

Cheers,

Richard

On 2012-10-10 12:15 PM, Louis Hone wrote:
> What do you use to bring it back to the right speed in your computer?  I've
> never had much success with plugins. I always hear artifacts except on
> material that need less than one semitone correction.
>
> Louis Hone
>
> 2012/10/10 DAVID BURNHAM <[log in to unmask]>
>
>> One thing you have to be careful of when transferring at the wrong speed
>> is the playback characteristic.  Since this is a frequency curve, playing
>> the record at the slower speed will displace the frequencies on the curve.
>>   One way to get around this, if your amp and workstation can do it, is to
>> record the disc flat, (no playback characteristic), and then generate the
>> appropriate curve in the computer after the record has been brought back up
>> to speed.
>>
>> db
>>

-- 
Richard L. Hess                   email: [log in to unmask]
Aurora, Ontario, Canada           (905) 713 6733     1-877-TAPE-FIX
http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.