Help me understand my MRL tape.

[Chris Shaeffer]

Sorry, Dave- I caught your additions after I typed up that last mind-boggling revelation of mine... Muchas gacious. Its not really *that* confusing an issue- I'm just new to it! I'm sure it will click sooner or later. I can't expect to get it all down in just a few days.

Glad the beer goes well with calibration conversation! I almost picked up some Anchor Porter for this evening, too. Too bad I didn't or I'd join ya.

-Chris

 

[Chris Shaeffer]

That explains the excessive crosstalk and funky sound I was getting when driving it hard- according to what +6/185 as MOL for the Q 456...

(crunch crunch - 355 MRL tape=0 on the meter....0 on meter= somewhere much higher than I thought it was and close to the MOL of the tape - crunch crunch)

Oy. I'm about tapped. Now I *really* can't wait for the #$*! pinch roller to get here.

Off for some light night time reading before sleep- I think the 48 manual will do nicely....

-Chris

 

[Beck]

It is confusing because it is confusing!

The factory specified operating level for the 48 is 250 nW/m. So if you have an MRL 355 nW/m cal tape (31J429?) you treat it the same as a 370 nW/m cal tape, because they are the same. The 355 nW/m cal tapes are referenced to a 1 kHz tone. When playing a 700 Hz tone it is 370 nW/m or +6, because of the different energy levels of the frequencies

Use the following chart from Quantegy and consider your tape to be +6 370 nW/m.

http://www.quantegy.com/Audiorecordersetup.asp

So, select 370 operating level from the pull-down menu on the far left. Next look over the results to the right. If you want to go with factory spec then set your VU meters to +3 VU while playing the 1 kHz tone from your test tape.

The 48 will easily handle 320 nW/m or +5 and will give you a slightly better S/N ratio. If you want to try that, the chart says to set your meters to +1 VU while playing the 1 kHz tone.

It all comes down to what you want your meters to do for you. They can more accurately represent where the true level is and you can try to stay at or near 0 VU, or you can have the meters zeroed at 250 nW/m and push levels well into the red to reach MOL.

Personally, if I’m not using noise reduction I like running a ½” machine at true 320 nW/m +5 (not European G320) for 8 tracks or less.

The chart below is from Jay McKnight of MRL. It may shed some light or make things more confusing.

 

[A Reel Person]

Aaahh! Thank you!

That puts it all in perspective.

This morning, I was contemplating scanning my tape reference card & posting it, but you beat me to it! My reference card is a laid out a bit differently, but your level reference nicely explains what we've been talking about.

 

[Chris Shaeffer]

Yup. I actually feel like I have a solid grasp of what the MRL tape is telling me and what my meters are telling me now. I'm sure there is plenty more that I don't get- but as far as this topic goes the various things that were confusing me magically cleared up when I realized the conflicting sources I've been reading are talking about different reference frequencies and opperating levels.

I may not have it *right* but the picture building in my head is at least consistent with what I've learned so far. The odd behavior when the meters went well into the red is because 0dB on my meters (which read 0dB with the 355nW/m 1k MRL tape, or +6 given that the 0dB reference for the machine is 250nW/m) is actually the MOL of the tape. MOL, I'm *guessing*, is the max level for no distortion and the peaks of my test records with *well* above that.

Time to dig out the voltimeter and figure out what my acutal input levels are.

Thanks yet again. I hope I'm not being too dense- I really do appreciate everyone's time and helpfulness
Chris

 

[evm1024]

SNIP!


Time to dig out the voltimeter and figure out what my acutal input levels are.

Thanks yet again. I hope I'm not being too dense- I really do appreciate everyone's time and helpfulness
Chris

You are on top of it. When using the volt meter just remember that dB is a ratio. And that dBv is referenced to 1 volt.

So -10 dBv (the tascam 0 VU output for unbalanced lines - RCS jacks) is:

-10 dBv = 20 * log (0.316v/1v)

This just says that 316 mV is -10 (lower) than 1 volt.

--regards

 

[A Reel Person]

Zoink!

................

 

[A Reel Person]

Biff! Bam! Pow!

...............

 

[A Reel Person]

Aw, c'mon!

Don't you guys just love my tape reference sliderule card? Aren't you jealous? Heh.

See the cool things you can pick up in the Burbank/Hollywood media complex? There's practically a studio on every block! There's media suppliers galore! Having slouchy neighbors like NBC, ABC, CBS, MCI, Universal, Paramount, Fox and Disney probably doesn't help matters, either. Heh.