[linux-audio-user] Reel to Reel Tape, Speeds and Software Equalisation

[Steve Fosdick]

A friend of mine has some old reel-to-reel tapes which we'd like to transfer to CD.  Unfortunately most of the material was recorded at 3 3/4 inch/sec or 1 7/8 inch/sec and the only speed my reel to reel machine will do reliably is 7 1/2 inch/sec.

I can record the output of the tape machine running at 7 1/2 inch/sec and then use software re-sampling (sox, or sndfile-resample) to get a file that plays at the correct speed but I wonder if I should also be applying some equalisation in software as multi-speed machines usually have different equalisation constants for different speeds.

So, does the equalisation compensate for the record process or playback process at a given speed or a combination of both.  If it compensating only for playback then I should be OK, otherwise I presumably should be applying extra EQ in software - anyone know how I could calculate what, assuming I have the usual LADSPA plugins at my disposal and that the signal has already been through the playback EQ for 7 1/2 inch/sec?

TiA,
Steve.