Become a Site Supporter and Never see Ads again!

Author Topic: Spectrum analysis to calibrate tape azimuth?  (Read 7200 times)

0 Members and 1 Guest are viewing this topic.

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Spectrum analysis to calibrate tape azimuth?
« on: January 27, 2008, 08:47:29 PM »
Hi all,

I'm planning to digitize my old cassette masters, which means I'll have to calibrate the azimuth on my tape deck. I'm a newbie in this aspect, so bear with me.

The quick'n dirty way would be to do the calibration by ear, and turn the screwdriver (or dial, for those with a Nak deck), until the best sound is achieved.

But I wonder if a spectral analysis software could act as a visual aid, displaying in real-time what's going on when the head is being aligned?

I know Audacity, Soundforge etc have spectral analysis of sorts, but is it usable for this purpose? Or would some standalone software be better suited?

When running the azimuth calibration, what should I look for on the screen? Best s/n ratio, high frequencies, stereo balance, or other variables?

Thanks a lot in advance!

/Jan

This is the list of plugins and software I found:
http://www.kvraudio.com/forum/viewtopic.php?t=109698&highlight=frequency+analyzernd
http://www.kvraudio.com/get.php?mode=results&st=adv&soft=e&type[]=70&f=0&fe=0&linux=1&mac=1&osx=1&win=1&free=1&sf=0&receptor=&sort=1&rpp=15
http://nixbit.com/search/reduced-spectral/
http://www.note2.com/content/view/128/55/
http://allworldsoft.com/cgi/search.cgi?s=1026&t=2&w=2
http://zeeman.ehc.edu/envs/Hopp/sound.html

Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline Church-Audio

  • Trade Count: (44)
  • Needs to get out more...
  • *****
  • Posts: 7573
  • Gender: Male
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #1 on: January 27, 2008, 09:12:12 PM »
Hi all,

I'm planning to digitize my old cassette masters, which means I'll have to calibrate the azimuth on my tape deck. I'm a newbie in this aspect, so bear with me.

The quick'n dirty way would be to do the calibration by ear, and turn the screwdriver (or dial, for those with a Nak deck), until the best sound is achieved.

But I wonder if a spectral analysis software could act as a visual aid, displaying in real-time what's going on when the head is being aligned?

I know Audacity, Soundforge etc have spectral analysis of sorts, but is it usable for this purpose? Or would some standalone software be better suited?

When running the azimuth calibration, what should I look for on the screen? Best s/n ratio, high frequencies, stereo balance, or other variables?

Thanks a lot in advance!

/Jan

This is the list of plugins and software I found:
http://www.kvraudio.com/forum/viewtopic.php?t=109698&highlight=frequency+analyzernd
http://www.kvraudio.com/get.php?mode=results&st=adv&soft=e&type[]=70&f=0&fe=0&linux=1&mac=1&osx=1&win=1&free=1&sf=0&receptor=&sort=1&rpp=15
http://nixbit.com/search/reduced-spectral/
http://www.note2.com/content/view/128/55/
http://allworldsoft.com/cgi/search.cgi?s=1026&t=2&w=2
http://zeeman.ehc.edu/envs/Hopp/sound.html



You cant do that with out a tape that is in proper alignment for your deck. You need a alignment tape try contacting the company that made your deck and see if you can purchase one from them.
You cant align every tape to your deck or your deck to every tape that would take forever.. But you can make sure your deck is in good alignment to it self. Any other tape deck you used for recording should be pretty close.

for warranty returns email me at
EMAIL Sales@church-audio.com

Offline Church-Audio

  • Trade Count: (44)
  • Needs to get out more...
  • *****
  • Posts: 7573
  • Gender: Male
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #2 on: January 27, 2008, 09:14:19 PM »
Hi all,

I'm planning to digitize my old cassette masters, which means I'll have to calibrate the azimuth on my tape deck. I'm a newbie in this aspect, so bear with me.

The quick'n dirty way would be to do the calibration by ear, and turn the screwdriver (or dial, for those with a Nak deck), until the best sound is achieved.

But I wonder if a spectral analysis software could act as a visual aid, displaying in real-time what's going on when the head is being aligned?

I know Audacity, Soundforge etc have spectral analysis of sorts, but is it usable for this purpose? Or would some standalone software be better suited?

When running the azimuth calibration, what should I look for on the screen? Best s/n ratio, high frequencies, stereo balance, or other variables?

Thanks a lot in advance!

/Jan

This is the list of plugins and software I found:
http://www.kvraudio.com/forum/viewtopic.php?t=109698&highlight=frequency+analyzernd
http://www.kvraudio.com/get.php?mode=results&st=adv&soft=e&type[]=70&f=0&fe=0&linux=1&mac=1&osx=1&win=1&free=1&sf=0&receptor=&sort=1&rpp=15
http://nixbit.com/search/reduced-spectral/
http://www.note2.com/content/view/128/55/
http://allworldsoft.com/cgi/search.cgi?s=1026&t=2&w=2
http://zeeman.ehc.edu/envs/Hopp/sound.html



If you had slate bursts on your tape you could I use 10k and 100hz then I measure the output of these two and make sure they are the same on the playback deck and then you have alignment. But with out that on your tape its impossible to align them all.

for warranty returns email me at
EMAIL Sales@church-audio.com

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #3 on: January 28, 2008, 09:26:31 AM »
You cant do that with out a tape that is in proper alignment for your deck. You need a alignment tape try contacting the company that made your deck and see if you can purchase one from them.
You cant align every tape to your deck or your deck to every tape that would take forever.. But you can make sure your deck is in good alignment to it self. Any other tape deck you used for recording should be pretty close.

Hi Chris,

My understanding was that a "test signal tape" is only good for restoring the deck to factory settings, ie. the optimal alignment for playback of commercial prerecorded tapes. It has been discussed here:
http://taperssection.com/index.php/topic,44898.0.html

Since my masters were exclusively recorded with a Sony WM-D3, I need to align the head especially for this scenario. So I need to roll one of my own actual masters while I adjust the azimuth, not the test tape.
It won't be that time consuming - once I got it right, I can stick to that setting for all tapes.

Back to the topic of software. Did anyone try this in realtime while doing the adjustment???

/Jan
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline Brian Skalinder

  • Complaint Dept.
  • Trade Count: (28)
  • Needs to get out more...
  • *****
  • Posts: 18886
  • Gender: Male
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #4 on: January 28, 2008, 09:37:14 AM »
once I got it right, I can stick to that setting for all tapes.

I wouldn't assume that all your masters require the exact same azimuth setting.  Alignment on the record deck may have drift over time.  I'd align each and every master.  They're probably all quite close, maybe the same, but I wouldn't count on it without confirming.
Milab VM-44 Links > Fostex FR-2LE or
Naiant IPA (tinybox format) >
Roland R-05

Offline Church-Audio

  • Trade Count: (44)
  • Needs to get out more...
  • *****
  • Posts: 7573
  • Gender: Male
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #5 on: January 28, 2008, 09:38:30 AM »
You cant do that with out a tape that is in proper alignment for your deck. You need a alignment tape try contacting the company that made your deck and see if you can purchase one from them.
You cant align every tape to your deck or your deck to every tape that would take forever.. But you can make sure your deck is in good alignment to it self. Any other tape deck you used for recording should be pretty close.

Hi Chris,

My understanding was that a "test signal tape" is only good for restoring the deck to factory settings, ie. the optimal alignment for playback of commercial prerecorded tapes. It has been discussed here:
http://taperssection.com/index.php/topic,44898.0.html

Since my masters were exclusively recorded with a Sony WM-D3, I need to align the head especially for this scenario. So I need to roll one of my own actual masters while I adjust the azimuth, not the test tape.
It won't be that time consuming - once I got it right, I can stick to that setting for all tapes.

Back to the topic of software. Did anyone try this in realtime while doing the adjustment???

/Jan

Sorry my bad I did not know that all your other tapes were only on one machine.. The only way to do it would be this.. Take the playback of a tape from one machine * the one you plan on using  to dump everything * and then compair it to the original machine record onto your computer both machines at the same time. Then use fft via a waterfall window to compair the two waveforms and "quasi" align them that way.

The thing is this you need that original machine in order to compair the original with the reproduction thru the Nak deck, if you dont have that you dont have a means of comparing the alignment.

If your just looking at frequency response by it self you dont really know what the "actual frequency response is" because you dont have proper azimuth to begin with. So you would not know what you were looking at. And adjusting it until the "frequency response " was the widest might not yield proper azimuth. So all you can do is

A- find the original machine to compair it to the known machine...
B- Find the alignment tape of the original machine and align the playback heads on your Nak to it.. that's a good possibility BUT DONT do this if you dont have a nak test tape to put your nak back lol hey that ryhmes!
C- Do it by ear and "guess" the alignment.

d- just stick the dam tapes in a play them back..
for warranty returns email me at
EMAIL Sales@church-audio.com

Roving Sign

  • Guest
  • Trade Count: (0)
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #6 on: January 28, 2008, 10:17:27 AM »
Just use a screwdriver and your ear!!! It aint that tough!

It's painfully obvious when the tape is aligned.

Transferring takes enough time as it is...dont drive yourself nuts.

Offline tilomagnet

  • Trade Count: (0)
  • Taperssection Regular
  • **
  • Posts: 148
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #7 on: January 28, 2008, 03:07:15 PM »
^^^

Correct.

Even if it could be done somehow, why trust some spectral analysis for the correct azimuth settings rather than your ears? Adjust the PB azimuth of your deck while monitoring with headphones until it sounds best to you. You don't need any alignment tapes, test tones or whatever.

Offline it-goes-to-eleven

  • Trade Count: (58)
  • Needs to get out more...
  • *****
  • Posts: 6703
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #8 on: January 28, 2008, 03:11:54 PM »
Baudline is my favorite real-time spectrum analyzer. It is free but it only runs under linux.

New product - Get your NEUMANN active mounting bars
Active microphone mounting bars for Schoeps and AKG, and Naiant AKG, ready to ship

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #9 on: January 29, 2008, 07:14:00 AM »
Baudline is my favorite real-time spectrum analyzer. It is free but it only runs under linux.


Yeah, I was looking at the Baudline site, it seems really clever. What is the nearest equivalent for Windows?

I might still "play-by-ear" for the azimuth aligning, but looking at the spectrum could be a good learing experience nevertheless.

/Jan
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline ironbut

  • Trade Count: (0)
  • Taperssection Regular
  • **
  • Posts: 87
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #10 on: February 01, 2008, 09:42:18 PM »
Azimuth is the relationship of the tape to the head. Testing azimuth is done by checking the phase of one channel against the other. A 15khz signal is played back to an attached dual trace scope using a Lissajous setting. The two signals are overlaid and should present as a single 90 degree line. This process should be repeated with a 10khz signal. This is how it's done on a reel to reel. If the azimuth wasn't checked before the recordings were made, you'll just be guessing. If you don't have a test tape to calibrate both machines, your also out of luck. I use Spectra by Audiofile Engineering. Kinda pricey for a one shot thing. I say, just go for it and do the transfer. If you have access to a Nak Dragon, it has auto azimuth which you might be able to calibrate to the deck you did your recordings on by running a test tape on it then having the Dragon calibrate to it.

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #11 on: February 08, 2008, 06:01:28 AM »
Even if it could be done somehow, why trust some spectral analysis for the correct azimuth settings rather than your ears? Adjust the PB azimuth of your deck while monitoring with headphones until it sounds best to you. You don't need any alignment tapes, test tones or whatever.

Sure, but it would be nice to follow the transfer visually, even if it's just to take a glance in case the alignment drifts off slightly and I wouldn't notice by listening...

I found a software that does just this, except that it's a custom utility for studio reel tape machines only :P
For those interested, specs and screenschots:
http://www.audicon.com/padbody.htm#PCSoftware


« Last Edit: February 08, 2008, 06:17:45 AM by sunjan »
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #12 on: February 11, 2008, 03:40:40 AM »
I found a software that does just this, except that it's a custom utility for studio reel tape machines only :P
For those interested, specs and screenschots:
http://www.audicon.com/padbody.htm#PCSoftware

I dropped a line to Greg Orton, old school studio guru, who was involved in Audicon and the software above. I though some of you might be interested in the answer I got:

Quote
The padnet/hardware and it's software are unique to the ATR-100 tape recorder.  It uses the summing of the audio output of the individual tracks to mono then measures the voltage like an RMS voltmeter.  When playing back a high frequency signal (usually 10 to 20 Khz range) the sum of the channels will show a dramatic peak output voltage while adjusting the azimuth and the in phase condition is reached.  It is wise to set the azimuth at the highest frequency you have on the alignment tape then check the next lowest frequency to make sure you weren't 360 degrees out of phase when setting azimuth at the highest frequency.
 
Studios simply sum all the channel of a tape recorder to one bus and monitor the signal output of that bus with the VU meter.  The levels of each channel on the consol should be relatively the same and make sure the individual channel EQ's are turned off.  This is really the only way you can accurately adjust the azimuth for a 16 or 24 track head.
 
The other common way for setting azimuth on a two track recorder is using an oscilloscope with X and Y inputs.  One channel goes to the X input and the other channel goes to the Y input.  When the tracks are in phase, the scope will display a 45 degree line tilting up from left to right( / )  when the tracks are 180 degrees out of phase you will see a circle ( O ) and when you are 360 degrees out of phase you will see a line tilting down left to right ( \ ).
 
I believe most of the DAW software have phase measurement capabilities but not in realtime.
 
Hope this helps,
 
Greg Orton
« Last Edit: January 02, 2009, 01:34:27 PM by sunjan »
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline it-goes-to-eleven

  • Trade Count: (58)
  • Needs to get out more...
  • *****
  • Posts: 6703
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #13 on: February 11, 2008, 09:08:00 AM »
Fyi, Wave has a phase measurement scope.

New product - Get your NEUMANN active mounting bars
Active microphone mounting bars for Schoeps and AKG, and Naiant AKG, ready to ship

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #14 on: February 11, 2008, 11:09:07 AM »
Fyi, Wave has a phase measurement scope.

Apologies for my ignorance, but Wave is something else than CD Wave?
I was checking the software overview, but I'm not familiar with this one:
http://taperssection.com/index.php/topic,62294.0.html

Thanks,

/J
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

Offline it-goes-to-eleven

  • Trade Count: (58)
  • Needs to get out more...
  • *****
  • Posts: 6703
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #15 on: February 11, 2008, 11:51:26 AM »
Sorry.. I should have said wavelab and not wave.

New product - Get your NEUMANN active mounting bars
Active microphone mounting bars for Schoeps and AKG, and Naiant AKG, ready to ship

Offline sunjan

  • Trade Count: (0)
  • Needs to get out more...
  • *****
  • Posts: 2004
  • Gender: Male
  • Taping since 1988, 28 years of fine recordings...
    • Just a handful of stuff I put on etree
Re: Spectrum analysis to calibrate tape azimuth?
« Reply #16 on: February 12, 2008, 06:05:43 AM »
Sorry.. I should have said wavelab and not wave.

T+ thanks freelunch! Do you know if real time monitoring is supported in older versions, or only the latest?!

/J
Mics: A-51s LE, CK 930, Line Audo CM3, AT853Rx (hc,c,sc),  ECM 121, ECM 909A
Pres: Tinybox, CA-9100, UA5 wmod
Recorders: M10, H116 (CF mod), H340, NJB3
Gearbag: High Sierra Corkscrew
MD transfers: MZ-RH1. Tape transfers: Nak DR-1
Photo rig: Nikon D70, 18-70mm/3.5-4.5, SB-800

 

RSS | Mobile
Page created in 0.188 seconds with 58 queries.
© 2002-2019 Taperssection.com
Powered by SMF