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Author Topic: Mrl number  (Read 1957 times)

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Offline porcupunctis

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Mrl number
« on: September 14, 2014, 04:14:51 PM »
I just placed my order for the 1500 tape mod.  I have one mrl test tape that I use for my Tascam 32.  21 24 is the number.  7.5 is IEC2, 250 nWebers.

Will this work for the 1500?  At least for 7.5ips.
Randall Massey
Teacher of Mathematics
Lifetime audio-electronics junkie

Offline Doc B.

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Re: Mrl number
« Reply #1 on: September 14, 2014, 06:01:50 PM »
Yes, IEC2 is the same thing as NAB. What we call IEC with respect to the Tape Project is IEC1, also known as CCIR.
Dan "Doc B." Schmalle
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Offline Big Al 954

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Re: Mrl number
« Reply #2 on: September 14, 2014, 07:46:04 PM »
There is a handy table in this MRL publication on using different test tapes for different speeds / EQ

http://home.comcast.net/~mrltapes/eq-shift-tables.pdf


Page 7 has the table for 7.5" NAB to 15" CCIR (IEC 1).
 You would also need to compensate for your tape being 1dB lower at 250nW and CCIR is at 320nW

Fluxivity Conversions are in this MRL paper
http://home.comcast.net/~mrltapes/choo&u.pdf

Alastair Reynolds
Broadcast Radio Engineer

Offline porcupunctis

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Re: Mrl number
« Reply #3 on: September 15, 2014, 02:41:06 PM »
Thanks Doc and Al.  Looks like with a little compensation on the meter this will take care of most of my calibration needs.

If I calibrate the deck at 7.5 ips,  won't the deck be pretty well tuned for 15 is and 3.75ips as well?

Randall Massey
Teacher of Mathematics
Lifetime audio-electronics junkie

Offline Big Al 954

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Re: Mrl number
« Reply #4 on: September 17, 2014, 01:29:19 AM »
Hi Randall,
It would be best to adjust at each speed individually if the 1500 permits this.I have only ever worked on Studers,Revox,Otari,Ampex ,MCI and Nagra decks so I really don't know the capabilities of a 1500.

The different speeds have different turnover frequencies for the Eq. The MRL table is compensated for these  differences to allow a user with one tape to use it for different speeds and eq standards. If the 1500 deck is limited in the Eq adjustment, then I would optimize it for the primary speed that you intend to use and compromise for the lesser used speeds or go all the way and build an Eros tape head pre ( free plug for Doc).
Let us all know how you go
Cheers
Alastair Reynolds
Broadcast Radio Engineer