Universal Tape EQ converter

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fredbloggstwo
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Universal Tape EQ converter

Post by fredbloggstwo » Thu Oct 28, 2021 11:34 am

Hi All,

I have accumulated a few NAB tapes over the year and playing them back is usually a bit of a pain - I use a Studer A80RC machine and involves swopping out the Reproduce channel cards (I could just swop the EQ plug ins but that would then involve setting up the cards again) and I was wondering if anyone has come across a line-level piece of equipment for transcripting a NAB (now IEC2) tape played back on a IEC1 machine, and vice-versa.

Come to think of it a device for the Reproduce side and the Record side would be even more useful, so one could record a IEC2 tape on an IEC1 Recorder, and again vice-versa.

Thoughts.

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mediatechnology
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Re: Universal Tape EQ converter

Post by mediatechnology » Thu Oct 28, 2021 3:32 pm

DSP-based .vst plug-in?

fredbloggstwo
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Re: Universal Tape EQ converter

Post by fredbloggstwo » Fri Oct 29, 2021 8:16 am

Hi Wayne,

Thanks for the reply.

I thought a bit about a digital domain answer but wanted to stick in the analogue domain if possible. Judging by the rush of replies, it looks like I will just have to switch replay amps when necessary. :)

Cheers.

Mike

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mediatechnology
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Re: Universal Tape EQ converter

Post by mediatechnology » Fri Oct 29, 2021 8:48 am

Do you have tables of the EQ values at various frequencies that could be used to compare them?

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mediatechnology
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Re: Universal Tape EQ converter

Post by mediatechnology » Fri Oct 29, 2021 10:37 am

The RIAA EQ that I have on one of my boards is switchable from RIAA to Inverse RIAA.

If you could figure out what the differences in curves amounted to and could reconfigure the RIAA network to switch between tape standards you could have a network that would go from either standard to the other.

I discuss it at Lathe Trolls: https://www.lathetrolls.com/viewtopic.php?f=9&t=5848

fredbloggstwo
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Re: Universal Tape EQ converter

Post by fredbloggstwo » Fri Oct 29, 2021 2:32 pm

Further research (lurcing) brought the enclosed PDF to light from MRL which makes things a bit easier.
02-209 MRL Choosing and using tapes.pdf
(143.08 KiB) Downloaded 23 times
Page 8 is a real nugget of information. As the author (Jay McNight) points out in the text, you can reverse the columns of "Recorded Frequency" and "Playback Frequency" for those tables at the same speed by simply changing the polarity of the "Playback Level" column.

Regards

Mike

Fragletrollet
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Re: Universal Tape EQ converter

Post by Fragletrollet » Sun Oct 31, 2021 10:54 am

Although software, U-He Satin has a bunch of repro modes available with visual feedback over the frequency curve. Can be further manipulated with the tape machine side of the plugin (it's a tape sim after all).

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mediatechnology
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Re: Universal Tape EQ converter

Post by mediatechnology » Sun Oct 31, 2021 11:34 am

fredbloggstwo wrote:
Fri Oct 29, 2021 2:32 pm
Further research (lurcing) brought the enclosed PDF to light from MRL which makes things a bit easier.

02-209 MRL Choosing and using tapes.pdf

Page 8 is a real nugget of information. As the author (Jay McNight) points out in the text, you can reverse the columns of "Recorded Frequency" and "Playback Frequency" for those tables at the same speed by simply changing the polarity of the "Playback Level" column.

Regards

Mike
That's what I was looking for.
In CoolEdit I think I can setup a filter based on entering the levels and frequencies with text.
Haven't done it in awhile but I recall doing that for RIAA and I-RIAA.
You might also be able to do that in Audacity.

fredbloggstwo
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Re: Universal Tape EQ converter

Post by fredbloggstwo » Wed Nov 10, 2021 9:18 am

Hi all,
just to round this subject off, I took the useful tables from Jay McNight's paper and put them and their counterparts into a spreadsheet and thought I would share it. I also converted the VU dB levels to voltage in case you prefer them that way. If anyone finds any glaring mistake, please let me know.

Interestingly, it also implies that you could take a 7.5 ips calibration tape and interpolate the tables for playing it at 15 ips and thus EQ beyond 20 kHz if you so wish.

Kind regards

Mike
Attachments
EQ conversion tables V4.xlsx
(24.71 KiB) Downloaded 17 times

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mediatechnology
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Re: Universal Tape EQ converter

Post by mediatechnology » Wed Nov 10, 2021 1:07 pm

Thanks for sharing the spreadsheet.
I gave my alignment tapes to a neighbor who does restorations and I'll forward this to him.

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