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  2-Track Analog Tape Alignment
 

 
Aligning an analog machine is easy. Basically the settings are as simple as adjusting a stereo - there's volume, treble and bass. The "record bias" is sort of like tuning in to the radio station you like... not a big deal. Just realize that each channel has a volume/treble/bass setting, and there's a volume/treble/input setting for the record side of the machine... so don't be intimidated by this process.


The goal of all of this to to end up with 3 alignment tones at the beginning of your master tape. This is so that each channel sounds the same, and so the mastering engineer can set up his/her machine to sound the same way yours did... in terms of volume, treble and bass.

You need to have a 250 nW/M alignment tape and a tone generating oscillator. The frequency response curve of the tape will either be NAB, AES, or IEC/CCIR - NAB used to be the standard for 7 1/2 or 15 ips, but AES may be the standard now. Get alignment tape for the speeds of your machine (try Micworks or ATR Services). Also get some splicing tape (1/2" or 1/4", depending on your machine), some single edge non-lubricated razor blades, some leader tape (preferably plastic), and be sure you have an editing block that's easy to get to.

Not recommended, but ok in a pinch: If you can't find an oscillator, simply play your alignment tape on your analog deck, set the 1k tone on the both channels of the tape for a PLAYBACK OUTPUT LEVEL of 0 vu, and record the tone onto your digital system setting the input so the digital meters input signal reads minus 12. Then record the 10k and 100hz tones (from your alignment tape) the same way - tape output level at 0 vu, digital input meters showing -12. Good idea: Even though you recorded stereo tones, it's more ideal to delete one side and clone the other side over to replace it. Make sure it's perfectly lined up in exact sync with the first side, that way it's exactly one identical tone going to both sides. Set each channel to minus-12, onto a cdr for future use. Print each tone three times in a row so you have 2 - 3 minutes of each tone. That cdr will then become the tone generator for your console. This just isn't a great idea if your machine isn't really stable on the high frequencies.

Now then - back to the machine.

(1) Play the alignment tape and set the PLAYBACK head (output) level of the 1k tone to -2dB on the machine meters. That was easy.

Now you have to find the "high frequency" playback level (NOT the high frequency record level). It may be on the front where it's easy to find, and it may be inside the machine where it's easy for a technician (or you) to find. On some machines you take off the bottom panel of the deck and it's right there.

(2) Play the 10khz tone and set it for -3 vu on the meters on the machine. This is where it can be important to have a new alignment tape. An old alignment tape can have wear on the edges, and possibly cause the meters to fluctuate. If you have a new tape and you see the meters moving around instead of staying still (like 1k probably did), it can also be because (A) the heads and tape guides on the machine are worn unevenly (B) the motors are older and not stable (C) the tape tension adjustments or tilt of the capstan is incorrect. (Here are the experts to contact if the problem is really radical.)

(3) Set your tape deck to playback the CUE (or record head) level. This used to be called Sel-sync on older machines. Repeat steps (1) and (2) for the RECORD HEAD (CUE) adjustments. Remember, these are different pots than the ones you adjusted when you did the PLAYBACK settings. It's possible that there may not be an adjustment for the high frequency adjustment for the cue depending on the machine.

Now take off the alignment tape and set the machine back to the PLAYBACK head.

(4) Put your BASF 900 tape on the machine "Heads out" (the full reel is on the left, empty on the right). Roll off about 6 feet of tape onto the floor. Set the area of tape that's close to the machine into the splicing block and use your razor blade to cut a diagonal spice - toss the 6 feet of scrap tape.

Take your leader tape (if it has arrows on it, aim the arrows in the direction of the take-up-reel) and hand-thread about six feet onto the take up reel. Then cut a diagonal splice in the leader tape, and use the splicing tape to join the two tapes. Use your razor blade You should now have the 6 ft. of white leader tape wrapped around the take-up reel, sliced to the BASF 900 which comes from the supply reel. Thread the tape through the machine tape guides and MAKE SURE THE RECORD SIDE OF THE TAPE IS UP AGAINST THE HEADS, NOT THE TAPE HEAD GUARD!

Roll one-and-a-half to two minutes of tape forward, and edit in (insert) another 4-6 foot section of leader tape and thread the machine again. Roll another 30 seconds of tape forward, and edit in another six foot section of leader tape. Rethread the machine and roll it back to the first section of tape.

(5) Plug in the tone generator (either the oscillator or the cdr) into your console and play the 1k tone so that the output meters on your mixer read 0 vu or minus 12dB on digital meters. Both left and right should be exactly the same. While watching the PLAYBACK level on your analog deck, record the 1k tone and set the RECORD INPUT LEVEL so that your playback meters show 0 vu. Record just enough to get that level to 0 vu.

(6) Next, play the 10khz tone on your oscillator/cd, but play the level so that the console meter shows minus-five on the vu meter, or -17 or -18 on the digital meters. Find the machine's BIAS ADJUST (or bias set) for the speed you're recording at (hopefully at least 15 inches per second). Again, it may be under the bottom or back panel that you've removed from the machine.

While you are playing that 10k tone, record it onto the 1st section of tape. Never mind if the machine's meters look funny. Turn the bias adjust down (counter clockwise) a pretty decent amount. You'll see the machine meters go down.

Now start slowly turning the bias adjust up, watching the machine meter of the channel you're adjusting. Keep turning the bias up till you see it reach a peak, or a high point on the meter. This point could be at -5 or -6.5 or -3. It doesn't matter. You'll find that if you keep turning the bias UP, at some point, the machine meter level will start to go down. This is good! Experiment. Turn the bias up and down to kind of see where that peak occurs on the meter.

Ok, you can stop experimenting now. Turn the bias down, slowly bring it up to that peak spot, continue turning up the bias till you see the machine meter drop 1.5 dB if you're recording at 30 ips. (If you're recording at 15 ips, the meter should drop 4 dB.) So if the meter peaks at -5, increase the bias till the meter reads between -6 and -7 (at 30 ips). This is the amount of "over bias".

Do the same for the other channel. It's ok to change the console/oscillator's output if you need to - the important part is how much the meter drops from the high point. Just keep doing this whole alignment process over the same area of tape - that 1 1/2 minutes you have at the head of the reel. It won't hurt the tape to keep recording over what you've recorded on before... for doing tones that is...

Note: Some tape manufacturers recommend different bias settings, and different machines may require different bias as well. This one is just a general overall recommendation for BASF 900. Ask your tape supplier (or manufacturer) to tell you what's best. Here's two numbers for BASF tech support: 800-371-0152 and 877-284-2600.

(7) Now set your oscillator/cdr back to 1khz and turn the console level of that signal back to 0 vu (-12 digital). Record that tone onto your machine and set the RECORD LEVEL (not the playback level) for 0 vu on both channels. Whew! That was easy.

(8) Now set the oscillator to 10k at 0 vu (-12 digital) on the console. Still on the same piece of tape, set the HIGH FREQUENCY RECORD setting (yep, it's another tweaking pot somewhere hidden in the machine) so that the machine meters read 0 vu.

(9) Double-check your 1k tone by setting the oscillator to 1k at 0 vu on the console. Set the RECORD LEVEL for 0 vu (it may not need changing).

(10) Now... there may or may not be a pot (potentiometer) to tweak this next part. You want to set your oscillator for 100hz at 0 vu on the console. I don't have to keep mentioning the -12 on digital boards, right? Look to see if you have a LOW FREQUENCY PLAYBACK LEVEL adjustment. If you do, record the 100hz tone and set the LF PLAYBACK to read 0 vu on the machine. If you don't have that adjustment, you're stuck with whatever the machine gives you. It may be +1 or -0.5, but in any case, it's worth it. It's analog. Do still record the tone, even if your machine doesn't have that adjustment.

(11) Another easy one. Play your oscillator 1khz at 0 vu on the console. Set your machine to INPUT (the tape doesn't even have to be rolling). The meter on the machine is showing you the input signal now, not the PLAYBACK signal that we've seen all along in this process. Find the INPUT CAL (or input meter) pot.... yes... somewhere inside the machine probably... and set the machine meters to read 0 vu. This is so that whatcha see is whatcha get.

(12) Now reset the machine to the PLAYBACK head mode and take the tape back to the top. You should now record 30 to 40 seconds of a 1k tone (0 vu on the console) at 0 vu on the machine - another 30 to 40 seconds of a 10khz tone (0 vu on the console) after the 1k tone, and last another 30 seconds of a 100hz tone on the tape. These are your alignment tones, and you should print a set of these for every project you mix. If it's a 4-song demo or f it's a 12-song album, record tones and keep them there at all times.

The extra 30 seconds of blank tape that follows the alignment tones is there in case you need to re-bias your machine, like if someone brought in a different brand tape for you to mix on. The 3rd leader is called a pad, and it's good to put on there even if you're the only one using your machine. Let's say that you mix three songs this month, and then 2 months later you want to check the record alignment (a good idea). You'd have to record on the tape to check the record alignment, right? That's what the pad is for. Saves you having to search for blank tape to record on. Now you're ready to start your mix. Zero the counter at your last leader - always let the machine roll a good 5 to 10 second before the downbeat of your song. At the end of each song, let the tape roll at least 10 to 15 seconds after the final sound of the song finished. Put in another 15 seconds of leader tape between songs.

Once you've done this process a few times, it will seem easy, and won't take you more than 15 minutes. To lessen the print-through, always store your tapes TAILS OUT. Take off the take-up reel (full of tape) when storing the tape. For your next project, you'll take off the (former) supply reel and use it as the next take-up reel for the recording to end up on. Store tapes in a cool dry place away from any speakers or other magnetic field (unless you like remixing the whole banana again). Enjoy that analog sound!

After a while when you're comfortable with this setup, click here for an additional step of alignment refinement.


Created 11/29/00 Modified 3/30/03
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