The answer to the head question can be found in the manual for the BR-20, which uses the same heads, part number 5378301800 for both play and record.
The BR-20 has a High/Low operating level switch that normally switches between 250 nWb/m and 320 nWb/m. However on page 6 of the manual we see it can be alternately setup to switch between 320 nWb/m and 520 nWb/m.
So apparently the BR-20 will do it with the same heads as are on the 32. The BR-20 should also be a good study in a view to beefing up the 32 for the job. A link to the BR-20 manual is below:
http://www.tascamcontractor.com/ftp_resources/files/manual/BR-20_manual.pdf
I guess I’m a little surprised the 32 (or at least not all of them) can’t be setup at a higher level. My 22-2 is able to adjust up to 514 nWb/m right out of the box. The heads are similar to that of the 32, but it actually has two different part numbers for the record and play heads. However, a substitution part is listed that is the same for the 22-2, 32 and BR-20, for both record and play.
Anyway, I hope that helps.
Dave offers some good advice as far as best practices for lowest distortion. However, there are longstanding disagreements about standards, especially those of North America compared with the other side of the pond.
This is one of those thorny subjects where there really is no one right answer, and in fact many do set their reference fluxivity (VU Deflection 0 dB) at OPL (Operating level) for a given tape. That would be around 500 nWb/m for GP9 tape.
Since tape doesn’t actually “clip”, but rather softly compresses the peak signals, the true maximum operating level is really much higher than the “recommended maximum operation level.” Quantegy’s Maximum Operation Level recommendation is not well explained, but based on the tape specs it must be OPL, and not the other MOL (Maximum output Level). At 500 nWb/m GP9 is nowhere near 3% 3rd harmonic distortion. It is more like 0.8%.
Tape manufacturers could do a lot more on their web sites to explain this in simple terms. Quantegy’s website is wholly inadequate, and is about as useful as nothing at all. See the chart at the following link: “Recommended Maximum Operating Levels”
http://www.quantegy.com/html/recordersetup.html
OPL (operating level) depends on machine, tape speed, track width and the maximum acceptable level of 3rd harmonic distortion, based on the user’s judgment for the type of material he/she is recording, and the dynamics of the material.
Based on Quantegy's standard testing conditions, we are looking at a recommendation for ¼” half-track @ 15ips. The test reference level for GP9 is 320 nWb/m. But here’s the important part. Under these testing conditions with that reference level the 3rd harmonic distortion is only 0.06%. So you can see just how far we have to go before true maximum operating level, which is a limitation of increasing distortion as the tape begins to saturate.
Keep in mind that 1% is pretty standard for the format. And in many cases 2% 3rd harmonic distortion is just detectable, and again depends on the material you’re recording.
A machine’s reference fluxivity can be set somewhat below a tape’s recommended maximum OPL for the cleanest, most distortion-free recordings. Where each person finds that sweet-spot between distortion and noise floor is really up to them. It also has a lot to do with how you want to read your meters. For mastering to half-track, I personally like to set my operating level a couple dB down and keep any peaks below +3 VU, for lower distortion and highest frequency response. I felt my 22-2 worked best with GP9 @ +7 referenced to 0 VU.
~Tim
