Tape Recorder Alignment

by Curt Taipale

Alignment of a professional grade reel-to-reel tape recorder is a piece of cake. Once you understand the procedure, the process is fairly routine. Even most semi-pro machines made today are reasonably easy to align. By comparison, consumer grade machines are usually a nightmare worth paying someone else to do.

Why bother with alignment in the first place? It is true that you could probably establish some sort of individual alignment on your tape machine, and that as long as you only record and playback your tapes on that particular machine, the tapes will sound just fine. But what happens if you need to send your master tape across town or across the country to have a quantity of cassette tapes or CD's printed from your master. Your fervent prayer is that when you get those copies back, that they will sound exactly like the tape sounded in your studio. However, if your playback machine isn't aligned exactly as the duplicator's machine is aligned, there is little chance of a match.

An Exchange of Standards

Routine alignment of the record and playback electronics of a tape machine is basically an exchange of standards. The first exchange of standards is to adjust the playback electronics to correspond with the tones on a laboratory reproduce alignment test tape. Laboratory test tapes are manufactured one at a time to exacting standards of quality. Not surprisingly, these test tapes are rather expensive. The two best known manufacturers of test tapes for the recording industry are Magnetic Reference Laboratories and Standard Tape Laboratories.

Now we accept the settings of the playback electronics as the standard, and set the record electronics to correspond with the playback settings. If the machines in your studio are aligned based on the laboratory test tapes, and the machines at the duplicator's plant are also aligned to this standard, then the duplicator will hear your tape as you meant for it to be heard. (Obviously there are other variables that could alter the sound of your tape, such as choice of monitor speakers and the acoustics of the listening rooms, but those are topics for another discussion.)

Repro alignment tapes are manufactured in all popular tape widths-1/8" (cassettes), 1/4" (most stereo reel-to-reel machines), 1/2", 1", and 2" (the last three widths mostly used with multitrack machines). They are also available in various track formats-mono, quarter-track, two-track, four-track, eight-track, sixteen-track and twenty-four track. And they are available in all popular playback speeds-30 ips (inches per second), 15 ips (30 ips & 15 ips available on all professional machines), 7.5 ips (used in semi-pro gear and many broadcast machines), 3-3/4 ips (available on semi-pro gear and cartridge machines), and 1-7/8 ips (primarily used with cassette decks, although also used for documentation purposes in broadcast and other applications). Most studios have machines that use the same width of tape but have different track formats that they can use, like a multitrack machine that has both a sixteen-track head stack and a twenty-four track head stack available. For this reason as well as economy, most studios purchase the mono test tape in the width(s) they need and use it for alignment on both head stacks, rather than purchase both a tape formatted for 16 tracks and another for 24 tracks.

The only reservation in using a mono format alignment tape for track formats other than mono is that the low frequency response will not be totally accurate due to the fringing effect. Fringing is a phenomenon created when a tape recorded on a larger track format is played back on a head with smaller tracks. High and midrange frequencies are not affected, but because of the longer wavelengths, low frequencies picked up on the fringes of the playback track are coupled to the track, and will play back more strongly than they were actually recorded. For this reason, when using a mono alignment tape to adjust the playback electronics of any machine with more than one track, the low frequency reproduce alignment adjustment should be made during the record alignment. This can actually allow for a more precise setting, as you will learn in a moment.

Track Formats

There are plenty of track formats to choose from-mono (full track), stereo (either quarter-track or two track), and multitrack (usually considered four tracks or more). A full track mono reel-to-reel machine simply has one track that records on nearly the full width of the tape. This kind of machine is often used in mono broadcast applications for announcements, voice messages and so on. Special mono heads in various widths are built for labs that manufacture repro test tapes.

Consumer grade stereo tape recorders typically use the quarter-track format and record on tape that is 1/4" wide. These machines allow the user to record program material in one direction; then when the tape reaches the end of the reel, he turns the reel over and records in the opposite direction. The left and right tracks on this kind of head are staggered as shown in figure 1. In fact, the popular semi-pro four track recorders that use 1/4" tape simply fill the two open areas with two more recording tracks. The tracks are numbered 1 through 4 from top to bottom. You could use such a machine to record a stereo tape for playback on your home quarter-track machine by simply recording the material on tracks 1 and 3 in each direction.

Multitrack machines use an extension of these formats. A one-inch eight track machine records eight tracks simultaneously on recording tape that is one inch wide. A two-inch twenty-four track machine records twenty-four tracks on tape that is two inches in width.

One of the apparent competitions in the marketplace over the past several years has been to increase the number of tracks that can be recorded onto a particular width of tape. Ten years ago, one inch tape was the norm for eight track machines, and sixteen tracks or twenty-four tracks were always recorded on two inch tape. Now some manufacturers have even been able to pack eight tracks onto cassette tape-tape that is only 1/8" wide! Will wonders never cease!?!

The marketplace drove the manufacturers to produce such machines. For the home user, physical space in his spare-room-turned-recording studio is at a premium, as are the dollars he can afford to invest in this kind of equipment. The other point that the small studio owner confronts is the cost of tape-smaller width tapes cost less than the larger width tapes of the same length.

On the technical side of that choice is the quality of the recorded sound. Wider tapes allow for larger track widths, so more signal can be recorded on tape for each channel. This can improve the signal-to-noise ratio of the machine. For example, a typical track width on a two inch twenty-four track machine is 0.043" with 0.041" between tracks, compared with a track width of 0.070" for a sixteen track head stack (with 0.057" between tracks) on that same machine. This allows for a 3 dB improvement in the signal-to-noise ratio for the wider track (16 track) format over the smaller (24 track) format. To a trained ear, that is a noticeable improvement. To expand on that thought, each track of a recording made on the sixteen track head stack has a 3 dB better signal-to-noise ratio than the same number of tracks recorded on the twenty-four track head stack. The recording made on the sixteen track head stack will be noticeably quieter to even the casual listener.

Similar comparisons can be made between two-inch sixteen track machines versus one-inch sixteen track machines, between one-inch eight track machines versus half-inch eight track machines, and so on. The smaller the track width, the less signal that will be physically recorded on the tape, which translates to a poorer signal-to-noise ratio, and that means more noise in the form of tape hiss. Especially when you get down to multitrack cassette machines (recording on 1/8" tape), the signal-to-noise ratio can be worthless.

Noise reduction to the rescue! The manufacturers have done what they can to improve the quality of transfer from head to tape and back. But God's laws of physics still apply, and they have had to turn to other processing devices to deal with the tape hiss. For analog recordings, noise reduction is the only realistic way of handling it. That is why you will see noise reduction systems available on nearly all of those machines. Many of them have the noise reduction system installed as part of the machine itself, which certainly saves on the fuss and bother of interconnecting a tape machine and a separate noise reduction system. The two front runners in the noise reduction arena are dbx and Dolby, with dbx being the more visible system in the smaller tape machine market.

Standard cassette machines use a variation of these formats. A mono cassette recorder has just one track, but it only records on half of the width of the tape. You could record a program in one direction, then flip the tape over and record in the opposite direction, while still recording only a mono signal. A stereo cassette tape recorder does not stagger the tracks like the quarter-track stereo machine does. Instead, the two tracks are positioned side-by-side at the top of the head. Program material is recorded in stereo on the two tracks in one direction, and then you can flip the tape over and record in stereo in the opposite direction.

A special use cassette format is a machine used for simple slide presentations. In effect, you could consider this machine a double-mono machine, because it uses two cassette-sized mono tracks stacked like a reel-to-reel two-track machine would have them. One of the tracks is used to record the mono program that will accompany the slide presentation. The other track is used to record the timed pulses which change the slides on the projector(s). The pulses are recorded on the tape by hitting a button at the appropriate spots while listening to the program material.

Step One

Before you even think about putting any tape on the machine, especially your master tape with all the hours invested in it, or an expensive repro alignment tape, you should clean and demagnetize the transport. Through normal operation, small piece of oxide will fall off of the tape and a small magnetic charge will be left on the heads. To ensure best performance, you need to keep the heads and all points that the tape comes into contact with as clean as possible. If you don't, it is very possible that a small piece of oxide will work its way between your tape and the head and lift the tape from the head; this small variation in the tape-to-head contact will not allow a clean recording if on the record head, or not allow clean playback if on the repro head. The end result will be a loss of high end at sporadic moments during the recording.

Likewise, a buildup of magnetic charge on the heads will also result in a loss of high end. High frequencies are always the first to go in any machine misalignment problem. The reason is that high frequencies are recorded very close to the surface of the tape, while low frequencies are recorded to the full depth of the tape. As a result, highs are more fragile.

If you handle the tape with your fingers right after you've eaten a bunch of French fries or onion rings, you're asking for high end loss at those spots. Be careful that you don't even wipe the sweat from your forehead with your hand before you handle the tape. Think to wash your hands before you handle the tape.

Cleaning the heads is a simple process. You should use a safe tape head cleaner containing trichlorotriflouroethane, or pure (97% ­ 99%) isopropyl alcohol. Do NOT use rubbing alcohol-it contains water. Dampen a soft cotton swab with the cleaner and rub it up and down the heads. This isn't a dainty process-don't rub the heads hard enough to push them out of alignment, but press hard enough to ensure a complete cleansing. Clean everything in the tape path, but be careful with the pinch roller. The tape head cleaner mentioned is considered safe for use on rubber, but alcohol can damage it. If you want to be safe, clean it with a lint free cloth dampened with water. It might seem odd, but many engineers rely on a household cleaning product called Formula 409 to clean the pinch roller (and only the pinch roller). It does a good job of cleaning off the oxide and leaves the rubber soft and supple. Not knowing for sure if 409 will leave any residue on the roller, I typically follow that up with the trichlorotriflouroethane or a water dampened lint free cloth.

Be careful when cleaning the capstan that you don't use too much fluid. The capstan is literally the shaft of the capstan motor, and the cleaning fluid or even water dripping down into the motor can dry out the bearings and wreck the motor over time.

A convenient way to clean the capstan is to trick the machine into thinking it has tape in the tape sensor, which will cause the capstan to start spinning. Now you can dampen your cotton swab with the head cleaner you're using and run the swab up and down the capstan slowly, which will clean the surface all the way around it.

To clean the pinch roller, once again fool the machine into thinking that tape is one the transport, and put the machine into PLAY mode. This will shove the pinch roller up against the capstan, causing it to spin along with the capstan. Clean the pinch roller as discussed above. If the pinch roller is really dirty, and it can easily be removed, undo the cap that holds it in place and hold it in your hands or in your lint free cloth as you clean it. This will allow you to scrub harder.

Head Alignment

We have all heard problems with head alignment. Anytime you put on a cassette tape, usually one that has been mass produced, on your cassette deck on the sound system or in your car, and hear the characteristic swimming sound of phase cancellations, you are hearing either a head alignment disagreement or a problem with the tape transport that is not allowing the tape to be pulled perfectly across the heads.

The swimming sound is typically more noticeable in the high frequencies, again because the high end is more easily affected by misalignment problems.

There are five basic head alignment checks to make. They are azimuth, zenith, wrap, height, and tape-to-head contact. Azimuth is probably the more critical alignment, because this is what will cause the phase cancellations. An improper azimuth adjustment will show up on playback through phase cancellations, because in effect it creates a time discrepancy between the tracks.

Azimuth is the alignment of the heads perpendicular to the direction of tape travel. If the azimuth is misadjusted, any program recorded on both tracks will be played back slightly out of phase.

Zenith is the alignment of the heads in the same plane as the tape. For example, the bottom of the head can be kicked out too far, which may cause the top tracks not to fully contact the head, and would cause the tape to ride up on the head, snapping back down occasionally. The zenith can also be misaligned so that the top of the head is shoved too far out. The head should be aligned so that the tape rides against it with smooth contact to the entire surface.

Wrap is the alignment of the head so that the tape contacts the head at the center, aligned with the head gaps. The wrap adjustment causes the head to swing in an arc centered on the middle of the head, and moves the center of the head from the left to the right of center, depending on which way you adjust the screw.

Head height is adjusted so that the tape rides perfectly centered from top to bottom on the head. You can tell this immediately just by looking at the tape as it rides across the heads.

Tape-to-head contact is just that - the head should be positioned far enough into the tape path to ensure good contact with the tape. If it were too far back, insufficient pressure would cause playback to be inconsistent.

Other than a cursory look, you probably won't need to adjust any alignment settings on the erase head. Your first alignment will be on the reproduce (repro) head, followed by a brief confirming check of the record head by switching the machine to the selective synchronization status. A more precise setting of the record head can be made during the first stages of the record electronics alignment.

Checking Azimuth

The azimuth alignment for the playback head is performed by playing back a high frequency tone on the laboratory test tape, connecting a dual trace oscilloscope to the outputs of the machine, and adjusting the azimuth set screw until the two traces lock closely together. If the machine is a two track machine, connect the outputs of the left and right channels to the oscilloscope inputs. If the machine is a multitrack machine, the most accurate alignment would theoretically be made by observing the two edge tracks (top and bottom, e.g., tracks 1 & 8 on an eight-track machine). Since the playback integrity on edge tracks is often inconsistent, you could choose the next two track in (e.g., 2 & 7), or you could bring tracks 1 through 4 up on the console and pan them all far left and send that signal to channel one of the scope, and then bring tracks 5 through 8 up on the console, panning them far right and sending that signal to channel two of the scope. This will provide a reasonable average of the head output.

You should first confirm a rough azimuth alignment at 1 kHz, and make a coarse adjustment at a medium high frequency like 8 kHz. Then follow through and make a fine azimuth adjustment at 16 kHz.

What if you don't have a scope? Here is a little less precise but nonetheless useful compromise. Take track 1 and track 8 (or tracks 2 & 7) and feed them to two separate channel inputs on your console, and pan both channels to the left. Play back a tone on the test tape and make sure that you are feeding equal levels through the console. For convenience, adjust the combined levels so that the meter reads at some convenient mark, like 0 VU or +2 VU. Now, play back the 8 kHz tone and then the 16 kHz tone, and watch the left output meter on the console. The meter will wag back and forth as the phase cancellations between these two tracks cause decreases and increases in the combined signal strength. Adjust the azimuth set screw so that there is a minimum of movement on the meter. The best you will probably see, playing back a 16 kHz sine wave, are fluctuations of about 1.5 dB.

Checking Zenith

Here you basically want to look for maximum output from the head. Since you know from the previous discussion that the high frequencies will be the first to go if the zenith is out of whack, use a frequency like 10 kHz or 16 kHz for this test. Using the same connection to the scope as used in the azimuth alignment procedure, move the zenith adjustment screw and watch for maximum output on the oscilloscope.

Checking Wrap

Wrap isn't as likely to change as the azimuth or zenith settings are, but there is a quick, easy way to check it. With a high frequency tone playing on the test tape, gently rub your thumb or finger up and down the repro head. Watch the VI meters on the tape deck-if you see the meters increase in level overall, then the wrap may need adjustment.

To adjust the wrap, use the same setup you had for the zenith adjustment, play a high frequency tone and move the wrap adjustment screw back and forth until you observe maximum output on the scope.

Checking Head Height

There is little reason for this setting to go out, unless you have had to replace the head itself. You can visually inspect the head to make sure that tape threaded on the machine pulls across all heads at their exact center. Look for the same amount of daylight of the head showing over the tape and below the tape.

Checking Tape-to-Head Contact

Once again, there is no reason for this setting to be off short of having the head replaced. If you do need to replace the heads, you would be wise to pay a knowledgeable repair shop to reset the heads the first time. Make sure you trust the shop though. I remember a friend of mine talking to a reputable audio repair shop about a proposed repair to his tape machine. At some point in the discussion my friend asked the guy to make sure that they checked the sel sync (selective synchronization) playback level. The guy's response was "sel what?" To make a long story short, I ended up doing the alignment-who would trust his gear to that repair shop after a comment like that!?!

Reproduce Alignment

With the repro head properly adjusted, you can proceed with alignment of the playback electronics. At this time, you will need to decide at what speed you want to do your recordings. With the laboratory reproduce alignment tape on the machine, locate the 1 kHz tone near the beginning of the tape (some manufacturers use 700 Hz). As you play the tone, locate and adjust the Repro Level trimmer on channel 1 until the channel 1 meter reads 0 VU. Once set, move to channel 2 and make the same adjustment. Continue this procedure until the repro level on all channels has been set.

Next, locate the 10 kHz tone on the test tape. As you play the tone, locate and adjust the High Frequency Repro EQ on channel 1 until the channel 1 meter reads 0 VU. Note: if your machine has separate adjustments for two different speeds, make your adjustment on the trimmer related to the speed at which the machine is rolling. (If your machine runs at 30 ips and 15 ips, selectable by a switch, but your trimmer adjustments say High Speed and Low Speed, the meaning is the obvious one-High Speed = 30 ips and Low Speed = 15 ips.)

If your repro alignment tape is formatted or compensated for the track layout of your head stack, you could follow through with the low frequency repro EQ setting now. If it is not (and in most cases it will not be), you can perform the low frequency repro EQ adjustment during the record electronics alignment procedure. To cover that base, let's assume that you can do this adjustment now. Locate the 100 Hz tone on the test tape. With the 100 Hz tone playing, locate and adjust the low frequency repro EQ trimmer (for the speed the machine is rolling at) until the meter reads 0 VU.

I told you this stuff was academic. Well, it is for pro gear and semi-pro gear. You couldn't pay me to mess with the alignment of a consumer grade machine.

What on Earth is Bias?

Before you proceed with the record alignment, you should make two checks. First, confirm that the record head is aligned. Do this by putting the machine in record status, feeding it a 10 kHz tone, and following the procedures outlined above. Even though you are recording, the machine should be in the Tape or Repro status so that you can watch the results of your record head adjustments as reflected in playback.

The next adjustment you want to check is the bias. Bias is nothing more than a very high frequency (often >100 kHz), very pure sine wave. It is fed along with the audio program material on to the tape via the record head during the recording process. It turns out that the transfer curve of any magnetic medium is not very linear. There is, however, a linear portion of the curve. When an AC bias signal is applied in this manner, it shifts or biases the program material out to the linear portion of the transfer curve, thereby allowing a mirror-image recorded output of the input signal.

To proceed with the bias adjustment, check the tape manufacturer's literature and/or the owner's manual for your machine to determine the amount of overbias recommended for your machine and the machine speed you will be using for recordings. The amount of bias required is a function of tape speed, type of tape, and the record head gap length. The speed is your choice, but this should serve to remind you that if the bias adjustment on your machine is set for a particular speed, it may need to be reset if you choose to record at a different speed. The type of tape is also your choice, however remember to re-bias the machine whenever you choose to record on a different type or brand of tape. The record head gap length is a function of the design and manufacture of your record head. What this says is that the bias requirements of your Otari two-track will be different than the bias needs of your MCI multitrack machine.

There is really nothing you can do about all of that. I simply mention it so that you can understand more about why all of these adjustments are necessary. The process is quite simple. Let's say that you have found through reading your manuals that the bias requirement for recording at 30 ips with Ampex 456 tape on your MCI multitrack machine is "1-3/4 dB overbias at 10 kHz." First you are going to feed the machine a 10 kHz tone at 0 VU. Put the machine into record (watching repro on the tape machine's meters), and adjust the Bias Adjust trimmer counterclockwise at first until you see the meter rise and then fall. This is the bias peak. Adjust the trimmer to locate the height of that bias peak. Now, you can either note where the meter is positioned at the moment, or use the Record Level trimmer to basically set the meter to a convenient, readable position on the meter's scale. Finally, go back to the bias adjust trimmer and continue to increase the pot (clockwise) until the meter falls 1-3/4 dB from where the peak was. The bias is now properly set on that channel. Don't worry about where the meter is reading at the moment-you'll come back to it right away. Continue with this process until the bias is adjusted on all channels.

Record Alignment

With the bias properly adjust across the board, feed a 1 kHz tone to the machine at 0 VU (on Input), and put the machine into record. Locate the Record Level trimmer on channel 1 and adjust it until the channel 1 meter reads 0 VU. Continue on with the rest of the channels.

Next, feed a 10 kHz tone at 0 VU (on Input), and adjust the channel 1 Record EQ trimmer until the channel 1 meter reads, what else, 0 VU.

If you haven't done the low frequency reproduce EQ adjustment, now is the time to do it. Set the oscillator to feed a 100 Hz tone to the machine, put the machine in record and adjust the channel 1 Low Freq Repro EQ trimmer until the channel 1 meter reads 0 VU. This procedure should establish a flat low end response for your machine. If you want to further refine this setting, instead of just selecting 100 Hz for this adjustment, slowly sweep the oscillator through from about 200 Hz down to say 50 Hz. You will probably see a small bump in the response fairly low, around 80 Hz, and another, larger bump (increase) at around 125 Hz. Examine these bumps and determine a procedure to obtain the smoothest low end on your machine. For some MCI machines, for example, the low end at 15 ips is smoothest when set for +0.5 dB at 125 Hz. Your machine may be different.

Confirmation

What you want to find when all is said and done is that 0 is 0 is 0. When you feed a tone (at virtually any frequency) at 0 VU from your console's oscillator to the machine, the machine should read 0 VU on Input status AND in Record status. You should be able to just switch back and forth between input and repro status while you are recording and see 0 VU in both settings. There will be some limitations to this depending on the machine. Many machines can record flat from 80 Hz through 20 kHz within ± 0.5 dB. Other machines will be lucky to read ± 2 dB from 100 Hz to 8 kHz.

Another way to confirm that you've done a good job of alignment is simply to try recording a tape or CD onto a couple of tracks on the machine, and doing an A/B comparison of first the Input signal and then Repro of the signal that you are recording. If you can tell NO difference between them, then put away your tools and start setting up for the session.

Recording Test Tones

In order for another engineer or the duplicator to play back your master tape on their machine and guarantee that it sounds just the same as it did when you recorded it, you need to physically show him your reference levels. You do this by recording a series of test tones on every master tape.

Not surprisingly, the test tones you want to record are the same ones you used during the alignment of your machine. First, record 60 seconds of 1 kHz. He will use this to set his machine for the proper playback level (0 VU). Next, record 30 seconds of 10 kHz. He will use the 10 kHz tone to set the repro high frequency EQ and as a course head alignment check. Next comes 30 seconds of 15 kHz, which is used primarily as a fine head alignment check, and to confirm high end response. Then, record 30 seconds of 100 Hz followed by 30 seconds of 50 Hz, both used to set the low frequency repro EQ for a smooth response.

Some will scoff at recording such long tones on the tape. They think it uses too much tape and isn't necessary. Those who say that haven't spent much time doing machine alignments from a client's master tapes, or doing dubs (making duplicate copies) of those tapes. Not only that, but tape is cheap compared to what you have invested in the performance on that tape.

Record Level

I've taught university level audio classes from time to time, and a question on one of my exams for the Audio 2 class reads something like "The term nanoWebers per meter is a) a rather cosmic entity, b) a unit of reference fluxivity, c) something to do with the price of condos in Florida, d) the reading of a sound pressure level meter." Despite my preference for answers "a" and "c", it turns out that "a unit of reference fluxivity" is the correct answer.

When the audio industry first started to corral all of the diverse directions of the manufacturers and inventors, the NAB (National Association of Broadcasters) chose to make 185 nanoWebers/meter as the standard record/playback level against which all other record levels would be compared. This became 0 dB, and machines were to be adjusted to read 0 VU at this record level. Later on, as tape manufacturers were able to come up with hotter tapes-tapes that could take more level without distortion or print-through problems-the term elevated level came along.

The first step was to a record level of +3, which simply means that the record level is 3 dB stronger than the 185 nWb/m reference. If your machine had been adjusted for a record/playback relative flux level of 185 nWb/m, and you then put on a test tape recorded at +3 [which happens to be 20 log (x/185 nWb/m) = 261 nWb/m] when you played any of the tones the meters would read +3 VU.

In this case, to set up your machine for a +3 Record Level using a +3 elevated level test tape (recorded at 261 nWb/m), you would simply adjust the repro level trimmer on all channels so that the meters read 0 VU. Later, when you crank up the record level so that the meter again reads 0 VU while recording and monitoring playback, you will have adjusted the machine for an elevated record level of +3. By extension, if you wanted to use a +3 test tape to set up your machine for a +6 record level, you would play the 1 kHz tone and set the repro level so that the meters read ­3 VU. Later, when you turn up the record level to 0 VU, you will have adjusted the record level for an elevated level of +6. [+6 dB = 20 log (x/185 nWb/m) = 369 nWb/m]

Make sure that you understand that all you are affecting with this entire record level process is the strength of the signal recorded on tape. If you measure the output of the machine, it will always read 1.23 volts AC which corresponds to 0 VU on the tape machine's meter. (This assumes that the machine is a professional or semi-pro machine using a +4 dBv output = 0 VU.) The terms related to 0 or +3 or +6 elevated record levels relate to the relative flux level (strength of magnetic flux recorded onto tape), not a change in the audio output level of the machine.

A World Class Set of Test Tones

Remember to record these tones on each of your analog master tapes so the next machine it is played on will properly reproduce your work.

 Frequency

Length

Adjustment

1 kHz

60 sec.

Level

10 kHz

30 sec.

High Freq EQ

15 kHz

30 sec.

Head Alignment

100 Hz

30 sec.

Low Freq EQ

50 Hz

30 sec.

Low Freq EQ

Hope that helps. In our world of digital recording, techniques like this may become a thing of the past. But at least you have a reference here for aligning an analog tape machine should the need ever arise.

Published in the January/February 1990 issue of Soundcheck Magazine. Used with permission.

Update

On occasion, people write to me for help understanding how to align their own analog tape decks. It has been nearly twenty years since I wrote this article, and nearly thirty years since I've actively been involved in aligning analog tape recorders on a daily basis. God's laws of physics don't change, so the information presented in this article is accurate to this day, however the art of aligning tape machines may eventually be lost. Even though I enjoy helping people understand various topics like this, I'm probably not the best person to ask about such techniques these days. If you need information beyond the details explained here, a search of the internet will bring up other articles that may add the information you need to answer your questions.


After making his living as a professional musician for twelve years, Curt Taipale returned to college and earned his Bachelor of Music degree from the University of Miami in 1980 (back in the days of analog tape machines). He has invested his career ever since as a recording and live sound engineer, a consultant, educator, and author. He served ten years on full time church production staff plus many more years as a guest sound engineer. He contributed three chapters to the Yamaha Guide to Sound Systems for Worship, has written numerous articles for several magazines, and is the Church Editor for Live Sound International. To learn more about Curt's background, see Who Are We?

 

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