(Other machines I've worked on have had switchable constants, or plug-in passive daughter boards with the constants and adjustments on them). If the MTR-90 is CCIR-switchable then this is a non-concern, however, I can't remember if the MTR-90 has switchable time-constants or not. The resultant errors, and end-of-travel settings make the whole notion of accurate 'calibration' pretty much a waste of time. Your chances of getting a flat response IF you're using the 'wrong' cards for your curve standard on both record AND playback are pretty much nil. 'correction' curves which 'approximate' CCIR playback on NAB machines etc, are for EMERGENCY use, when a tape comes in from a different standard, and there's no access to a correct machine, or a switchable-time-constant machine. If (as I suspect may possibly be the case, though I've no way of knowing) you're trying to align a NAB machine using a NAB tape to a 'CCIR/IEC behaviour' because somebody told you that CCIR sounds better than NAB, or something along those lines, I'll leave it at this: DON'T WASTE YOUR TIME. If the machine's nominal position is IEC/CCIR, then you won't be able to approximate NAB, and vice-versa.
It sets it at a fixed, 'somewhere-near-correct-for-the-nominal-curve' position. The 'Low Frequency Compensation' switch just disables the LF playback adjustment. Without some more details, nobody can tell you what to do, but above are a few possible comments based upon the information you've supplied thus far. It's like trying to match an EQ curve when the corner frequencies are in the wrong place.
If it's the last case, the time constants are not right, so you can't ever make it 'right'. Or are you attempting to align a NAB Machine to an approximate CCIR response, using a NAB tape? Which way? Are you aligning a CCIR machine to a NAB tape? or are you aligning a NAB machine to a CCIR tape? You ALWAYS align low end to record-to-playback, which is why I've italicized it each time. You can (shock!) use a SWEEP oscillator and find out for yourself what compromise is acceptable.īut your question suggests some conflict of data: You bring in CCIR/IEC, and you mention MRL and inter-standard correction/interpolation.įundamentally, in my book you NEVER align multitrack low end response to an MRL. However: It's really just about averaging for a poor low-end response, there's no magic. If you feel inclined, and you're assuread of their technical knowledge (as opposed from someone who 'once was told something') it might be worth asking them, to find out what this suggestion is based upon, because at 15ips on an MTR-90, I'm inclined to think it's inapplicable. Whoever suggested this may have overlooked the fact that you'll be working at 15ips, or may not be aware that LF response changes dramatically with speed selection. as a compromise, some people may suggest that you align for flat record-to-playback at 63Hz, which would give you a slightly warm 100Hz and a slightly cold 50Hz. The 63Hz-versus-100Hz is almost certainly referring to the 30ips head 'bump' at approx 100Hz, whereby if you align 100Hz record-to-playback 'flat' it's down at 50Hz, and if you adjust for flat record-to-playback at 50Hz, it's a couple of dB warm at 100Hz. You've brought several different aspects into one question, so there's no single answer. What are you aligning TO? and what are you aligning? I know i have to switch it on when i want to adjust the low frequency but after alignment is done do i keep it on. Lastly what does the low frequency compensation switch do. record aligment 1k=0VU, 10K =0VU but the low end is where im kinda confused. so repro and sync allignment 1K off the mrl the vu is set to -4ġ0K we set to -6.5.
The high frequency adjustments i think are fine just confused about the low end. Do i need to adjust the low frequency to match the iec1 curve when i first had it alligned to use ccir curve 63 hz was aligned to +2.31 over 0vu, we got that number from the mrl site when doing conversion from 15 nab to 15 iec1.
Is this the optimal frequency for this machine? If i use 63hz should I align it to reach 0VU. I have been told by a few people to use 63Hz rather than 100. When aligning the low frequency playback what is the best frequency to use for this machine. I am aligning the machine to use the iec/ccir curve at 15ips. Need some advice or help on setting up my otari mtr90.
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