Tape alignment

Bandrecorder afregelen

Alignment need not be super expensive and complex to be reasonably accurate. Using a simpler method, there may be errors, but not gross errors. Here are a few “common sense”: suggestions which may be helpful to make this a little easier:

1. 1) My suggestion is a deck with a fixed playback eq curve, no playback EQ adjust pots on the board which may have been tweaked in the past. The Pioneer RT-1011, or RT-1020 (the RT-1050 half track) are well made decks with fixed playback curves. This way you are trusting the manufacturer design for your playback alignment. If any errors exist, they would not be too great because it is a Pioneer… :righton: but this is a matter of assumed trust.
2. 2) Place the deck on its back. Remove the head cover (if there is one) You'll need a bright light. Check the guides and heads for physical wear. If the heads are deeply worn, the head can not be aligned. The tape will not fully contact the head gap, so your high frequency response will be way off, alignment would be futile. If the “slot” worn in the head appears to be more than 1 mil (the thickness of 1 mil tape) the wear is excessive, so the head will need to be relapped or replaced.
3. 3) If the guides are worn, most guides can be rotated to a non-worn area.

The order of alignment is as follows: Erase head, Play Head, Rec head.

1. 4) Obtain a section of clear leader tape, Maxell and TDK tapes came with clear leader. Splice the leader section within a reel of tape, perhaps near the beginning. This way you can run the machine to see how the tape is running through the transport.
2. 5) To adjust head HEIGHT, eye up the clear leader tape, and see that the top land on the Erase head Play head, and Rec head, meet exactly at the top edge of the tape. (the top land is the L ch) This needs to be exact, no part of the land should be above or below the top edge of the leader tape.
3. 6) Start the alignment with the ERASE head. The erase head is non-adjustable, but the guide is adjustable. The head land should be in perfect alignment. If it isn't, adjust the guide nearest the erase head up or down until the land is flush with the top edge of the tape. Run the tape deck to verify. Be sure to check the right guide as it may need to be raised up or down slightly. The tape path “wear” on the capstan should indicate if the guide has been readjusted in the past. If the shiny part of the capstan, the tape contact area is no wider than the tape, and then all is good.
4. 7) Do the same with the Play head, turn all three screws by equal increments until the land is just at the top edge of the leader tape.
5. 8) Do the same now for the REC head.
6. 9) Check the ZENITH or squareness of the heads to the guides by eye-balling them edge wise, in relation to the guides. Also look at the wear pattern on the heads. Slightly more wear at the bottom of the heads is normal for a 4 track, but not a lot more. If the wear pattern appears unequal, let's say more wear at the top head land, then the head was not square with the guides. Just do the best you can to align the heads to the guides, ie: no tilt forward or tilt back of the heads. Again, just use your light and eye them up.

BTW With new heads, the tape contact pattern appears after about 30 minutes of running, you can always make adjustments according to what the contact pattern looks like. It should be even along the height of the head, and the gap centered between.

1. 10) To adjust the PLAY azimuth, load a factory pre-recorded tape. Play the tape in mono. (very important) Adjust the Play head for max high frequency response. You can do this with your ears.

Load a second factory pre-recorded tape. Do the same, noting the turn of the screw, if any. Repeat with 4 or 5 pre-recorded tapes. Take the average of them. if three out of five play perfectly without touching the azim adjust, then leave it there. You are very, very close if not spot on.

1. 11) To adjust the REC azim, load a blank tape. Record a high quality source, and again the playback amp in mono mode (to combine the left and right channels) Turn the REC azim screw until you obtain max high frequency response, and you are almost done.
2. 12) Adjust the REC level, REC Bias and REC EQ, These adjustments are best made with a mono source to obtain the same result for each channel. First adjust the L ch BIAS for max output and also lowest distortion. Do this while recording and make only small adjustments here, as there is the tendency to lean to better hi freq response… better to favor a slight fall off of high freq resp and max output. Repeat for the Rt Ch.
3. 13) Adjust the L ch Rec EQ trap for most balanced sound, record a high quality source, and while recording flip the source/ monitor switch for comparison. The REC LEVEL pot should also be adjusted at this point. Again, record a mono source for this. Repeat for the rt ch. Balance the REC levels. Readjust the BIAS and EQ, flip the source/ monitor to verify.

Oh, and align to the tape you will be using. Other brand tapes can be used, but their responses will always be different more or less.

This may seem long and tedious, It isn't as difficult as it seems once you dive into it, Steve VK

Clarification on an important point, for used heads with normal wear, I do not advise doing the height adjust, nor the zenith. Just adjust the azimuth only as needed. The reason is that the tape will always tend to be guided through the slot that exists on the heads, just from normal wear, so making any changes would only misalign the slots that have already broken in, (we want all wear “slots” to remain in a straight line and not move anything) which may cause the tape to drag through the transport, or even possibly damage the tape edges. Studer heads are the exception, (Revox machines too) as these heads are machined to exactly the width of the tape, so these do not develop a groove from wear. Ferrite heads generally do not wear.

The complete alignment should only be done for new heads, or relapped heads. Exceptions are Studer heads with wear, and Ferrite heads ok too.

I overlooked many finer details, leaving much to common sense… and assumed basic mechanical skills. However the zenith adjustment can be tricky. As you adjust the head so that it is vertically in line with the guides, the adjustment of one screw will mess up the azimuth like crazy. So, all you do is turn the middle screw, (the azimuth screw) approx half as much as the front screw (or the rear screw if that's the one you turned) This will bring the azim back to a coarse alignment. As I mentioned, the head block is open and so it's easy to see the guides and heads. As the head screws are turned, notice what the head is doing. A person with just basic mechanical skills will quickly discover the interaction of the adjustment screws. The idea is to keep the azim as close as you can when setting the head height, and zenith. But this is no worry, since the azim need not be perfect at this point. If the head appears not tilted by eye inspection, this is ok as a coarse adjustment.

The azim is always the last adjustment on the head. As I explained in my former post, the azim can be set with a high quality source in mono mode. (pre-amp mode switch on “mono”) With the deck running, adjust the azim for max high frequency output. The ears need to be capable of hearing to about 8K or better to make this adjustment by ear.

The PLAY head azim set with factory pre-recorded tapes, the earlier easy listening tapes at 7.5 ips have better quality control, as the slaves for making them were calibrated to higher standards. This achieves reasonable results if a calibration tape isn't available.

The REC head azim is set with blank tape, with the deck recording. I suggest a high quality mono source, such as a Beatles mono CD. The deck source/ monitor switch is set to “tape” or “play” or “mon” (on playback), and the pre-amp mode switch on “mono”. (critical that the playback is in mono, as this sharpens your adjustment) Very small adjustments result in very obvious changes in HF response. The phase will be locked in too, preserving the musical timing cues in the stereo field. Simply turn the azim screw for max high frequency output. The avg REC levels should be set anywhere from -6 VU to 0 VU, ok for peaks to +3dB, sometimes higher.

Open reel decks are “hands on”, easy to work on, once a person gets a feel for it, and primed with basic knowledge. Most new owners tend to feel intimidated by their size, but actually an open reel is so much easier to service than a cassette deck. Don't be afraid of it.