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Author Topic: Group Buy of Multi-format Alignment Tape?  (Read 18270 times)

Offline stellavox

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Group Buy of Multi-format Alignment Tape?
« on: April 15, 2009, 09:58:52 AM »
I've had this discussion with a few of you enough times to warrant posting the idea here.

Project subsctibers apparently receive a 15ips alignment tape with IEC equalization.  For NAB EQ you are out of luck.  When you go to MRL you find that their "normal" tapes are one speed / one EQ only, and getting multiple tapes runs up a big bill real quick.

A few years back, I needed an alignment tape for my Sound Technologies 1500A and contacted MRL about making me up one "all purpose" tape with different speeds and EQ's.  They did and a 3 speed, 2 EQ tape cost me less than two single tapes.

Here's what I propose.  If there is sufficient interest, I'll contact MRL and see what they will charge for the following tape:  15ips - 30 seconds reference tone (250mw?), 60 seconds 10khz (or whatever HF tone) for azimuth adjustment; then say 15 seconds (each) of a series of 5? or 6? tones with IEC EQ, followed by the same number/frequency of tones at NAB equalization.  THEN, the same thing with NAB EQ ONLY for 7 1/2 ips.  Now you should have everything you need on one tape for most all playback needs - UNLESS you also want 3 3/4 ips NAB playback EQ.

I'm guessing that we could get a pretty decent price if we could guarantee MRL a quantity of say 6 tapes.

Waddyathink????

Charles


Offline ecir40

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #1 on: April 15, 2009, 11:56:42 AM »
I think for NAB 15 IPS and 7.5 IPS is considered the same so if you have the IEC tape from the tape project then all you would need is a NAB 15 IPS calibration tape.

I'm up for it since I don't have the tape project calibration tape and would love to have an all in one.
« Last Edit: April 15, 2009, 11:58:13 AM by ecir40 »
Brad

Offline audiolab1

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #2 on: April 15, 2009, 01:43:59 PM »
I'd be interested, depending on the price.
MRL has some 2-speed cal tapes, but they are either NAB OR IEC and they are only 2 tones each, 1kHz and 10kHz, IIRC.
That of course would be of no use to correctly set repro EQ.
Thanks for offering to look into this!

Andrew

Offline stellavox

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #3 on: April 15, 2009, 02:12:22 PM »
Brad,

7 1/2 and 15ips NAB playback EQ are the same, but what happens when you play a tape recorded at 15ips at 7 1/2ips?

Charles

Offline Ben

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #4 on: April 15, 2009, 02:58:08 PM »
You hear the music much slowwwwweeerrrrr.  :)
Set 45,Open baffle speakers,Otari 5050,,Pioneer DV-79AVi DVD/CD/SCAD player

Offline Dan Robertson

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #5 on: April 15, 2009, 06:36:38 PM »
Charles,

I would definitely be interested in one of these "all in one" alignment tapes, so count me in!

Dan

Offline rawbcca

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #6 on: April 15, 2009, 07:59:06 PM »
Charles,
  If you can make this alignment tape happen from MRL at a reasonable price, Put me down for one.
Richard
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Offline Brian

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #7 on: April 15, 2009, 09:09:39 PM »
I would be interested also.
Brian
Brian Downey

Offline ecir40

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #8 on: April 15, 2009, 09:25:53 PM »
Hey Charles,

Looks like this has gained at least 6 interest already :).

Here is a post Doc made in the past of what is on his alignment tapes.

http://www.tapeproject.com/smf/index.php?topic=685.msg3870#msg3870

I would say this would be the minimum requirements for an IEC and NAB alignment tape at 15 IPS.

One question I have is what would be needed on the tape to check the accuracy of a IEC and NAB eq?

Doc can you or anyone else chime in on anything else that would be needed on a tape like this?
Brad

Offline stellavox

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Multi-format Alignment Tape - so far
« Reply #9 on: April 16, 2009, 07:26:02 AM »
Wow - youse guys are quick!!

Let's see - from the posts so far I see the following potential test tape:

15ips: 30 sec of 1Khz reference; 60sec 10Khz and 60 sec of 15khz for azimuth adjustment

15 sec each 30, 60, 90, 1K, 10K, 15K all at NAB EQ

same as above at IEC EQ

finally 15 sec of 1K assymetrical

7.5 ips same as above except NO IEC tones

If my addition is right we end up with a tape that is a minimum of around 10 min long which could be expensive.  Let's see what MRL says - I will also ask them for suggestions to bring the cost down.


To answer ecir40's question about test equipment, I think you could get by with a "decent" Digital Volt Meter (DVM) HOWEVER you need to look at the accuracy spec for it's high frequency AC response.  The simple circuits in many "cheap" meters don't allow for good accuracy above 1Khz or so.  For example, my (cheap) old Radio Shack DVM has +-1% accuracy on DC, +-1.8% accuracy on AC up to 1Khz degrading to +-6% above 1Khz!  As we are dealing with sine waves here which should have low distortion, the True RMS capability of more expensive meters MAY not be necessary - unless it's the only way to also get accurate high frequency response.  To use the meter, you could hook it up to the output RCA jacks of the playback amp.

Doc's posting on how to set azimuth is a good one and of course having/knowing how to use a 2 channel oscilloscope is a real plus as you can "see" what's going on with both channels simultaneously.

Charles

Offline ESS John

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #10 on: April 16, 2009, 02:30:15 PM »

We would be interested in a 1/4" version of the multi-format alignment tape as described in the previous posting by Charles. I am new to this forum and do not know if there is an existing assumption about tape width in this case, but 1/4" and possibly also 1/2" would be useful to us.

I will be interested to see how MRL responds to the inquiry.

John

Offline High and Outside

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #11 on: April 16, 2009, 02:35:23 PM »
Just so you know, it's possible in some cases to use one tape to align to a different standard. There's some pretty good information on the MRL site about it. For instance, you can use your IEC tape to align for NAB, just set the 10K tone to +2.5. Conversely you can align to IEC with your NAB tape, just set the 10K tone to minus 2.5 and it'll be close enough for more purposes.

For another instance, you can play a 15 IPS IEC tape at 30 IPS and align to the AES curve, or play it at 7-1/2 IPS and align to IEC.

More Stupid Test Tape Tricks can be found in the extremely useful MRL publication "Choosing and Using..." 
Paul Stubblebine
Managing Director, The TapeProject

Offline docb

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Re: Group Buy of Multi-format Alignment Tape?
« Reply #12 on: April 16, 2009, 03:31:32 PM »
Something along the lines of an HP 410C or 400GL or 3400 AC rms voltmeter can be had pretty cheap these days and they typically have a bandwidth that goes from 20Hz to several MHz.

Here at the Chateau we use a Tek TDS 420 oscilloscope. It's a scope that allows you to assign a number of measurements to each of four traces. We just set it up for dual trace, take a measurement of rms AC volts from the repro, and rough out the rms to dB conversion in our head. Since we are adjusting the heads to hit the same voltage at every frequency rather than trying to log painstaking response curves this works quite well. And of course we can switch to X-Y display on the fly to adjust azimuth. I've watched Mike Spitz align an ATR and he does it pretty much the same way.
« Last Edit: April 17, 2009, 09:33:44 AM by docb »
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Offline stellavox

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UPDATE: Group Buy of Multi-format Alignment Tape?
« Reply #13 on: April 17, 2009, 08:59:31 AM »
Sent a "preliminary" Email to MRLyesterday outlining what we might be after - will forward their comments.  Did knote that one of their typical 5 minute tapes cost ~$135 and a 10 minute tape $200 - so there's the probable range of costs.

Paul is of course right that with the necessary info you can "correct" the various spot frequency readings from one EQ to another, and that his referenced MRL publication does have a lot of the necessary charts: HOWEVER this requires stretching one's (limited?) knowledge perhaps to the breaking point.  May be easier to spend some (reasonable amount of???) money to avoid this meltdown.

Want to add that to my first point on monitoring the tones should you have a test tape - in addition to hooking up a meter to quabtitively monitor the output you need to be able to hear what's there simultaneously so you know where you are on the tape - so I'd suggest hooking up the meter in PARALLEL with the preamp output.  Could do this simply with a RCA "T" adaptor and a cable with RCA connector on one end and the other end terminated with whatever connector you need to plug into your meter.  Most meters have sufficiently high input impedance that you won't load down the source at all.

Charles

Offline bobschneider

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Re: UPDATE: Group Buy of Multi-format Alignment Tape?
« Reply #14 on: April 17, 2009, 10:28:08 AM »
Want to add that to my first point on monitoring the tones should you have a test tape - in addition to hooking up a meter to quabtitively monitor the output you need to be able to hear what's there simultaneously so you know where you are on the tape - so I'd suggest hooking up the meter in PARALLEL with the preamp output. 

Or you can just plug headphones into the headphone jack, and the meter to the preamp outputs.  That's what I normally do when using test tapes.

BTW, I fully agree that you need some way to hear the test tape when you're using it.
Bob Schneider