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Author Topic: On the fly EQ change questions  (Read 4143 times)

Offline kipdent

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On the fly EQ change questions
« on: September 07, 2009, 02:22:14 PM »
This is my first post, and I'm excited to be here! I'm getting very close to taking the plunge back into R2R. I can't remember when I've ciphered as much as I have recently, especially looking at all the subscription permutations to the Tape Project. Of course, the other huge variable in this equation is choosing a R2R machine that floats my boat and is TPP compatible, though I think I'm close (thanks to all the members who have been patient with me in private e-mails!).

There are some questions about machines, though, that I've been trying to figure out:  If aligning the audio section to a particular EQ curve is so important (and complicated, it appears, on some machines), why is a simple switch between CCIR and NAB even provided on some models? Does one really have to sit down with an alignment tape, do the test tones and maybe fiddle with azimuth of the heads after simply flipping a switch from NAB to CCIR? I'm really wondering if it is more likely people with machines that have this facility just flip this switch and listen to their respective tapes recorded in either NAB or CCIR and don't worry about realigning the audio section each time--in fact, I wonder if the manufacturers of machines with this feature assumed that's what their customers would do? I'm guessing recording studios, when faced with doing this, methodically went through an audio realignment each time (and probably did so each session whether EQ was ever changed or not!). I just wonder how important this work is to hobbyists and what members with machines that have this feature actually do when they use this switch.

Kip Peterson
Vintage-centric system with Apogee Acoustics Scintilla ribbon loudspeakers, Micro Seiki RX-5000 turntable and other odd bits of tube and solid state gear. Now a proud owner of a Studer A80 RC Mk II tape machine!

Offline Tim

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Re: On the fly EQ change questions
« Reply #1 on: September 07, 2009, 02:51:36 PM »
Assuming your deck was aligned (mechanically and electrically) at the factory or by an experienced RTR technician, all you need to do is throw the Eq switch.   No need to change head alignment or re-adjust EQ.   The differences between NAB and CCIR/IEC are simple circuit changes and quite accurate in the decks I have tested.
Tim Leinbaugh
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with RTR specialty.

Offline ironbut

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Re: On the fly EQ change questions
« Reply #2 on: September 07, 2009, 03:17:34 PM »
Hi Kip, glad you decided to jump on into our little forum.

Tim's right. The alignment adjustments to the heads are for getting the interface between the tape and the head surfaces correct. These mechanicaladjustments should be correct irregardless of the eq or recording on the tape. The electrical adjustments are made to the eq circuit and are switched in or out as the IEC or NAB circuits are connected.

 About the only time you'd ever need to make changes to these adjustments are with archival activities where unusual track arrangements or large differences in the material the tape is composed of needed to be played. Folks who do this kind of thing for a living usually have custom headblocks built to make rapid and repeatable changes in things like head height and azimuth.
 The only reason I even mention this is confuse the issue,..(just kidding). Actually, the deeper you get into collecting old tapes the more often you accidentally buy a tape that has an unusual format. If you ever find yourself with one of these old tapes and you really want to hear it, it's much cheaper to send it to someone like Eric Jacob's The Audio Archive, Inc. and have it transfered for you.
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