How to properly calibrate a Reel to Reel machine?

I have adjusted the azimuth on tape decks before but seems to be much more complex with reel to reel. With reel to reels you are adjusting the wrap, height, zenith, and finally of coarse the azimuth. As far as I know reel to reel is constant in speed so slowing and speed as with cassettes won't be a problem. It's just a matter of mastering the calibration techniques and what equipment I would need to do so. Reference tapes would not be an option for me as these are pre-recorded reels that require a new calibration for each. The machine I will be using is the Akai GX-220D, strictly for playback.

 

You'd be chasing your own tail. The alignment in high-speed dupes can vary wildly from the beginning of the reel to the end, let alone from one reel to another. Not like you have tones either like you'd find on an album master.
IMO you should just have your heads aligned to a standard calibration reference, enjoy your tapes and hope for the best.

 

Okay, for calibrating, what could you use for a reference. I've had to hard time finding reference reels that would be great for calibrating that are younger than 5 years old. Would love some MRL's

 

An MRL alignment tape would be the gold standard and really all that's available nowadays but these are pricey and there are so many options available, I wish I knew exactly which is the proper one for a 1/4 track machine. Try emailing them and they should be able to help you out. You will also need an oscilloscope to use with the tape. It may be more worth the time and money to look for a professional technician in your area who can perform the alignment and also take care of anything else you may possibly need to bring the deck back up to spec.

 

And if all else fails theirs plenty of places that would be happy to archive my reel tapes for me if fixing my machine up becomes a money pit, no fun in that though! As far as I know it turns on, lights up, and motor works. That's always good sign!

 

It can be a lot of fun to get into, having someone else transfer them takes a lot of the experience out of it. If there's nothing wrong with the transport or electronics then all it should need is realignment, if you won't be recording then you won't have to worry much about calibrating the record electronics. I say get it fixed up and enjoy. Good luck!

 

No MRL, no proper test equipment, no knowledge, not aligned. No shortcuts to doing it right. Akai heads not forever, no proper low/high alignment settings. You have to change electronic components to align the electronics. Buy a proper machine you can calibrate with less hassle. Sorry to be blunt. A Pioneer RT 707 is a much superior 1/4 track machine. And longer lasting.

 

I appreciate the honesty, thanks for the Pioneer suggestion. I do have an oscilloscope lying around somewhere, hmmmm.

 

I agree with McLover 100%. But 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) 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... but this is a matter of assumed trust.
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) 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.

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.
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.

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.
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.
8) Do the same now for the REC head.
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.
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.
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.
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.
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

 

I'm here to learn...

 

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.

 

AMEN on your RT-707 comment. I owned one back when they initially hit the market & again in the late 1990's. I am currently using the single direction model, the RT-701. The're indeed very well constructed, and I've never had a second's worth of trouble. The 701 still works like new & the sonics are first rate to my ears. Direct drive motors (the only belt is the tape counter). Really heavy, tho. Avoid the 10.5" 900 series as their electronics are really buggy and $$$ to get restored if you develop trouble.

There is a website that's fascinating, and deals with all issues tape and other gear; Reel-to-Reel quite actively:

http://www.tapeheads.net/forums.php

The site is information-packed with really helpful posters. I haven't visited for awhile.

All the best,
GT

 

The tapes are full track so can work for any 1/4" format.

Another option would be to have somebody who has a well aligned machine to make you a set of tones. Assuming that their machine was properly aligned the tones should work just fine assuming that they're in the same format as you need. Tones recorded on a half track machine will not work for setting up a quarter track machine and visa versa. Of course this method assumes that the tones were made on a properly aligned machine or all bets are off.

Many studios did this to keep the wear and tear of the MRL tapes to a minimum. These were generally called 'house tones'. In fact they can be more accurate as there is no fringing effect, which is a condition that happens when you use a full track tape for low frequencies, as it can create a bass response that can read higher than it really is. Usually this is avoided by not using the MRL tape for adjusting playback low frequency eq. In fact in most cases the playback low frequency eq is adjusted while setting up the record electronics, mainly to eliminate the fringing effect.

Btw, the first head to align is the playback head. Once it's aligned properly the record head can be adjusted by monitoring off the playback head. Since the OP said he's only planning on recording, the record and erase head become somewhat irrelevant.

 

Ton to read, thanks for all the advice. The tapes I will be converting to digital are 40+ years old so I bet the frequencies are all off anyways. I'll definitely adjust the azimuth and as you said (The FRiNgE), you can mess it up bad if you touch the zenith and don't know what your doing. Of coarse if I wanted to get fancy I could ask my local shop for a custom calibration specific to my BASF reels. All my reels are the same BASF's. I will upload some pictures next week of the madness I just walked myself into, this should be good.

 

Can't resist! Alright alright you make a good point.

 

Now you recommend an Pioneer RT-707 over any Akai. What machine would you guys recommend that will work with 10 inch reels as well that won't break the budget. I mean from what it sounds like calibration might not be worth it if you don't know what your doing. If that is the case then a fully serviced Akai 4000DS would work with 10 inch reels for under $500. Possibly Tascam or Revox would be other great contenders.

 

Almost forgot about Technics. Okay I've narrowed my choices down. The AKAI GX- 635D, the Technics RS-1700 (although heard new heads are impossible to find), Studer Revox A77 or A700. As much as I would love the Pioneer RT-909 it's a little over my budget. Again thanks for the help!

 

I would suggest getting dialed into the Tapeheads Forum. You don't need to register to view all the discussions & posts, but to post questions & discuss, you will-just like here. Link follows:

http://www.tapeheads.net/forums.php


There are 8,191 Threads on JUST Reel-to-Reel topics-690 on Open Reel Tape Media by itself. Search it & you'll get guidance not readily available here.....

BTW, if you don't really NEED the larger reels to get started in this hobby, I still suggest (and I mean humbly suggest) starting with a well-maintained/restored 7" machine. If you find this r-2-r hobby clicks with you and desire to progress, keep your initial machine and patiently await the 10-inch unit you want to come to you. The larger reels need the inner NAB adaptors (they can wear over use & time) and the reels themselves can get warped somewhat more easily than the smaller 7" ones. Plus the blank reels (used and new) can be lots more costly. The larger machines also take up more room in most instances.

Just sayin' with respect,
GT

 

Thanks, and the only reason I need a machine that can play 10" reels is the due to the 10 inch reels I have already collected over the years that I would love to archive. I have a mix of 7" and 10" recorded material. Was kind of bummed to find out the RT-707 would not fit 10" reels.

 

You either love the Otari mx5050 or hate it… Steve hates it. I love it. It's a very versatile and capable machine, a very ubiquitous one (which means it's available for cheap) and I don't think I've ever seen one that took a beating it couldn't come back from. Might be worth looking into (unless you particularly hate it)

 

Cassette tapes are also constant speed, as with most tapes. The tapes are driven by a capstan, pinched by a roller. Any variation in speed would be in the drive motor itself or contaminants on the tape causing the capstan to slip. Sometimes we would have problems with stretched tape which was recorded and played at 15ips from too much cue-starting at the radio stations. Old, cheap-o reel to reel tape decks were sometimes rim drive.

 

They were fairly rugged but didn't sound all that great to me. I had a client who had an old one but the semi-pro Technics RS 1500 sounded significantly better, especially on the upper high end. I worked with a few Otari 24 track machines and they seemed to be much better.

 

I enjoy my TEAC A3440 very much. As far as calibration and bringing these things up to factory spec, that's what qualified techs are for. I'd destroy it within 5 minutes.

 

They do much better with outboard repro electronics but that's getting into the particularly high end/mad-scientist end of things. People do the same with the technics RS models. Even the stock electronics on some studer decks isn't up to snuff for some people. You can get back what you put into pretty much any unit but as it stands it's still a great machine for the money IMO