ã May 2000 by Eddie Ciletti

Since 1995 I've focused on the repair of digital tape machines — 4mm, 8mm and S-VHS — but it wasn't always that way... Three projects jolted me back to my roots. A man gives his son a TASCAM 80-8, a church wants to digitize forty-year-old sermons and a live Joni Mitchell recording (from the Main Point in Philadelphia some thirty years ago) recently arrived in the mail. These are reasons enough to compile some data and take out my digital crayons…

GREGORY PECKORY: TREND MONGER

Virgin analog freaks are scouring digibid.com and ebay.com for pro and semi-pro classics. I am afraid for them. Whether you already own or are thinking about buying an analog tape machine, it is important to know the maintenance issues, especially for that most expensive wear item, the head-stack. A deal is only a deal when you are capable of smiling after the selling price is mated with the maintenance cost. Tape machines have lots of electro-mechanical moving parts that wear out or get funky, even from lack of use. If your budget is large enough for "piece of mind," Otari continues to manufacture the MTR-90 III multitrack and inventory remains from Studer's final production run in 1999.

GEN-FLUX

I've made one very broad assumption for this article, that a new generation needs to become familiar with the idiosyncrasies of analog recording equipment — pro and semi-pro — including tape and the effects of aging. The dividing line is track density — 24-track translates into 3 tracks per quarter-inch; semi-pro is 4 to 8 tracks per quarter-inch, referred to as "narrow-format" within this article. A table will be provided in Part Two.

Part One is about analog idiosyncrasies, how to assess the machine and what to do when the VU meters are dancing instead of standing at attention. I will barely scratch the surface of alignment preparation before running out of space in this issue. Part Two will cover electronic and mechanical alignment. For a list of test equipment, check out the May 2000 issue or go to mixonline.com. At minimum, you should have an oscillator.

MOVING THE MOUNTAIN

Few project studios can boast a full-time technician let alone one with analog tape machine experience. Fewer experienced technicians are willing to make house calls because older professional machines need an overhaul, not a tune-up. You are encouraged to establish a healthy relationship with technical support personnel; they are human beings after all, performing a service that is a labor of love with skills that are exceedingly rare.

There are several third-party companies providing analog machine support — listed in the RESOURCES section of this article — some, like ATR Service, will even send a shipping container. For example, an Ampex ATR-100 shipping crate is $225 (an additional crate for the pedestal is $75). Empty crates are shipped via UPS. Cargo Inc (www.cargo-inc.com) will ship an ATR coast-to-coast for about $300 (insurance will vary). An Ampex MM-1200 crate is $475, shipping is about $600.

On the upside, analog machines will continue to be serviceable — now, after twenty, thirty or forty years and in the future — because they mostly consist of hardware that any skilled machinist can recreate. (No digital format will be as easy to support after manufacturers throw in the towel.)

CONSUMER ARCHIVE

On the consumer side — for the quarter-track stereo format, at speeds of 7.5 IPS and below — your only option is to find a good used machine. The Revox A-77 and B-77 are both excellent choices as are the Technics 1500 and the Otari 5050 series. All are three-motor decks with ten-inch reels available in speeds from 3 3/4-IPS to 15-IPS. If you need a machine that runs at 1 7/8, the Tandberg 9000X has three motors, 7-inch reel capacity and speeds up to 7.5 IPS.

18 WITH A BULLET

Tweaking open-reel tape machines triggers a list of "things to remember," here's the first batch:

• When threading, make sure the tape is snuggly wound around the reel hub before pressing fast wind or play. (Careless threading leads to stretched tape, bent or broken guides.)
• Use water-based cleaners on rubber parts. Do not use stuff that sez "rubber cleaner" unless you are sure it is water-based. Windex and Fantastic do a good job. Formula 409 works well on ceramic capstans. Don't let any cleaners or solvents get into the capstan bearing. Dilute if necessary.
• Always observe the tape as it passes through the guides, over the heads and between the capstan and pinch roller. Tape should not be riding up and down or buckling where the edges meet the guides. You should not be able to see the "edge tracks" of the head.
• Use 99% anhydrous (or denatured) alcohol to clean the heads in strong light. Do not use rubbing alcohol because it's 30% water.
• Keep tweakers in pocket protectors unless chaperoned or until you feel extremely confident (after reading both parts of this article).
• Odd behavior may be attributable to the machine but never rule out the tape. Since the seventies, high output tapes have been prone to shedding. Always inspect the heads and guides before calling a technician or grabbing a screwdriver.
• Demagnetize your tools.

FREAK-n-SEE RESPONSE

Tape machines don't go drastically out of alignment unless something is wrong — such as intermittent parts, bad tape or poor mechanical stability — but don't expect ruler-flat response like digital.  Figure-One shows the performance variables of a Studer B67 configured as a quarter-inch two-track, the format-equivalent of a two-inch sixteen track.  To show the relationship between speed and track width, consider the following... Compared to two-inch 16-track, 24-track machines running at 30IPS have difficulty with frequencies below 60 Hz the same as narrow-format machines like the Fostex E-16 running at 15 IPS. This is a head-related issue, only so much metal and wire can be crammed into a small space.

Figure Two is a half-inch cross-section of tape. From left-to right track density increases starting with half-inch two-track. The "narrow" formats are to the right of professional 24-track.  Wider tracks yield more signal, less noise, better low frequency response at higher speeds and more headroom across the frequency spectrum.

 

2A	2B	2C	2D	2E	2F
half-inch two-track	quarter-inch two-track half-inch four-track or,  a half-inch section of two-inch sixteen track	a half-inch section of two-inch  twenty-four track	half-inch eight track,  one-inch sixteen track, consumer "quarter track" stereo	half-inch  sixteen track	4mm (.157inch)  four-track  cassette

 

Figure Two: Squeezing more tracks on tape reduces low frequency headroom and increases noise. That's why narrow-format machines (to the right of two-inch 24 track) feature built-in noise reduction.

BUMP AND GRIND

Bass bumps and the natural saturation at extreme low and high frequencies is a form of peak limiting, giving analog tape a characteristic smoothness or that dreaded and overused word, "warmth." For years, recording engineers have been experimenting with speed (no comments), track width, elevated levels and noise reduction in an attempt find the best match for the material being recorded. 15-IPS half-track on quarter-inch tape was once the norm and noise reduction was a popular option. In the late seventies, 30-IPS, elevated levels and "no-noise" became the trend until the eighties ushered in the half-inch format, but that still wasn't quiet enough for purists who would rather not use noise reduction...

NOISE REDUCTION

It should be noted that there is nothing wrong with noise reduction (NR) other than the additional electronics required. Be a purist if you want, but sometimes noise gets in the way. The "fault" of NR is that it does not tolerate frequency response anomalies. Narrow tracks have exaggerated head bumps and reduced headroom at low frequencies. Headwear further antagonizes response at both ends, increasing low frequency bumps and decreasing high frequency response. This combination is deadly when NR is added and narrow format machines can not be operated without it.

All machines have playback and record adjustments in the midrange @ 1 kHz, but narrow-format machines often have no low frequency (headwear compensation) adjustment and minimal high frequency record EQ adjustment range. Tempting as it may be, BIAS should not be used to manipulate record EQ because its purpose is to minimize distortion. See Figure Three, BASF / EMTEC Bias vs Distortion curves.

Figure Three: Bias versus Distortion curves for EMTEC SM900
 
 

<< For Figure Three, insert image: basf900_30ips.jpg >>

THE LAP DANCE

It is important to emphasize that head surface condition is a prerequisite to an electronic alignment. If the high frequencies waver or increase in level after applying some drag to the supply reel, look closely as the tape passes through the guides as well as between the capstan and pinch roller.  Any up and down motion could cause the signal level to vary.  More likely, a worn head has diminished tape-to-head contact. Increasing tape tension is not an option especially when considering head prices...

Table One compares 24-track head prices from the manufacturer with those of a third party source. Dizzy? Worn heads can be resurfaced or "re-lapped," in this case for about 25% of the cost of a new head.  To get the most head life the machine must be well maintained to minimize normal headwear. Poor mechanical alignment can cause the heads to wear unevenly, the "good" end being sacrificed to match the bad end in the lapping process. Head restoration specialists can determine head life, so have those heads checked before purchasing a used machine.

HEAD PRICES
 

		Re-Lap	2-inch 24	2-inch 24
			OEM	JRF
Ampex-1200		$500	NA	$2000 / 2500
Ampex ATR 124		$615	NA	$ 4000 PB $ 5000 REC
MCI		$495	NA	$1750
Otari		$555	$4300	$2850
3M		$510	NA	$1850
Studer		$500	$3800	$2850
Tascam		$495	$1600

 TABLE ONE: Comparison of Lapping Charges to Head Prices from the Manufacturer (OEM) and from a third party (example courtesy JRF Magnetic Sciences).
 

Notes for Table One All third party erase heads $2000~$3500 (except as noted below)  Erase head for 3M M79 is either Saki or PLX ($1850)  All third party Ampex Heads are by Flux Magnetics  MCI, Otari and Studer heads are by PLX  3M head options are PLX and Saki (TDK)  Lapping charges are reduced $135 if erase ok

 

BASIC MAINTENANCE FOR ALL MACHINES

Use 99% (anhydrous) isopropyl (or denatured) alcohol on a cotton swab to clean the heads.  Do not use rubbing alcohol because that is 30% water.  To clean rubber parts, use only water-based cleaners such as Windex or Fantastic, dilute if necessary and wipe off excess with a damp cloth. Formula 409 works well on ceramic capstan shafts but don't let liquid drip into the capstan bearing.  Do not use "cleaners" designated for RUBBER PARTS or PINCH ROLLERS unless you are certain they are water based. Some are solvents that can damage or prematurely age a pinch roller — parts are getting more difficult to find and more expensive with each passing year.

DEMAGNETIZATION

The head assembly relies on electro-dynamic magnetism to function.  Static magnetism — as found in magnetic screwdrivers and loudspeakers — is the devil.  Head demagnetization is considered routine maintenance, but only when performed by experienced personnel.  Use ONLY the R.D. ANNIS  Han-D-Mag, as shown in Figure Four (available through JRF, see the RESOURCES section).  Throw away a demagnetizer with an ON-OFF switch as these are extremely dangerous.

Before demagnetization, remove any tape from the machine and turn the power off.  Power-up the demagnetizer away from the machine and do not remove power until the device is at least three feet from the machine. (I am being overly cautious AND I fully understand the inverse-square law.) Once powered, slowly move the demagnetizer tip toward the first head — the han-d-mag has a protective plastic tip — slowly moving up and down. Continue this motion while gradually pulling away from the heads until each has been demagged.  Be sure to demagnetize your tools before playing the test tape.  Inexperienced demagnetization is more dangerous than doing nothing, so again, do not attempt this process unless confident. An experienced technician will surely show you how to safely use "the force."

Figure Four: The Han D Mag

ALIGNMENT BASICS and TEST TAPE RESOURCES

Playback alignment requires reference tones from either a test tape or the "project" tones that accompany the master tape. A test tape is typically a full-track recording (across the full width of the tape).  Unless a test tape claims "compensation for multitrack reproduction," it can not be used to set low frequency playback level.  NO machine has a low-frequency RECORD adjustment.  In nearly every instance, accurate low-frequency playback adjustments are made AFTER first recording a bass sweep, which requires an oscillator capable of same. On a 3-head deck it is possible to playback while recording.  On a 2-head deck, the process requires more patience.  (Full alignment procedures will be detailed in Part Two of this article.)

The most  important reference tone is 1kHz for operating level, specified in nanoWebers per meter (nWb/m).  The Equalization (EQ) Curve is specified as either NAB / AES (American Standard) or IEC / CCIR (European Standard).  Make sure the test tape you buy or rent is the correct speed and EQ for your machine.  Most narrow-format machines are calibrated as per IEC / CCIR with rare exception.  The most common error is to attempt narrow -format calibration using an "American" NAB test tape.

Professional machines have a generously wide adjustment range while many narrow-format machines are extremely limited. Many TASCAM MS-16s do not have enough range in the bias control to accurately find the peak at 10kHz. Most Fostex machines have a continuously variable bias capacitor. Without a voltmeter or oscilloscope it is possible to be on the wrong side of the bias peak.

Note: Modern high output tapes are not a good match for older pro or narrow-format semi-pro machines, which may not have enough current to fully erase previously recorded material. Compared to older generations of tape, modern tapes can be an additional 1/2-mil thicker than the original "1 1/2 mils" for which the machines were designed. (1-mil is 0.001 inches or 25.4 microns.) Thicker tape is harder to pull and, if tension is not adjusted, could cause more than the usual amount of headwear. Attempting to operate any narrow format machine without its integrated NR is not recommended nor should the operating level be changed from the manufacturer's recommendation. While it may be possible to disable NR for selected tracks, there will never be enough headroom to sufficiently lower the noise floor for ALL tracks.

TRACK WIDTH PHENOMENA

The weaknesses of analog tape are also its strengths, but to compete with digital, the analog envelope has been pushed to new limits. The three high output tape formulations — BASF / EMTEC SM900, Ampex / Quantegy 499 and the former 3M product (996) manufactured by Quantegy as GP9 — are not new, but when combined with the "recent" one-inch two-track format, noise is at an all-time low and many of analog's idiosyncrasies are minimized. I won't say it's almost like digital. (Who said that?)

LAST LINKS

At this point, I have room enough to tell you to put up a new reel of tape, route an oscillator set to 1kHz to all tracks and press record. (Noise reduction should be bypassed.) Observe Input versus Playback and note the differences. If INPUT does not agree, you need a voltmeter to confirm that the incoming levels are good. OR, route the oscillator to one track at a time to see if there is an improvement (much less fun). Follow the machine's instruction manual for RECORD LEVEL and INPUT calibration. Buy an manual if you don't have one.

Rather than push the real estate issues for this column, be thankful for the web. There is so much useful information at these links:

To see a basic list of MRL and BASF test tapes:

http://www.jrfmagnetics.com/mrltapes.html

http://www.jrfmagnetics.com/basftapes.html (this includes cassette test tapes)

To visit the MRL site directly, visit http://home.flash.net/~mrltapes/

To see a really cool interactive site that shows how to align for elevated levels, go to http://www.Quantegy.com

Click HERE for more Parts and Service RESOURCES

CONDENSED ALIGNMENT PROCEDURE (In Part Two, this will be hyperlinked to the detailed procedure.)

1. PLAYBACK LEVEL (1-kHz)
2. AZIMUTH 8kHz and 16 kHz
3. High Frequency PB LEVEL
4. BIAS
5. RECORD LEVEL (1 kHz)
6. HF EQ (level): 10 kHz
7. 3-head deck:
8. RECORD BASS SWEEP while monitoring via Playback head. Align until peaks and dips fall on equal sides of "0VU," then select a low frequency that falls on "0VU." Print that tone and note it on the box. Include the bass sweep if the tape becomes a Mix Master.
9. 2-head deck:
10. RECORD BASS SWEEP. Check playback, noting the peaks and dips, then select a low frequency that falls on "0VU." Print that tone and note it on the box.

RESOURCES: Parts and Service
 

R. B. Annis  & Co., Inc.
(Manufacturer of Han-D-Mag Demagnetizer)
1101 North Delaware Street
Indianapolis, IN 46202
vox: 317-637-9282

Athan Corporation
George Athanisiou
Tape Path Components and Motor Work
50 South Linden Avenue #10
South San Francisco, CA 94080
650-589-5206 voice
650-742-9091 fax
mailto: athancorp@aol.com
http://www.athan.com/

ATR Service Company
Michael Spitz
AMPEX Tape Machines
ATR and MM Series
1600 Pennsylvania Avenue / Suite 23
York, PA 17404
717-852-7700 voice
717-852-7755 fax
mailto:info@atrservice.com
http://www.atrservice.com/

JRF Magnetic Sciences

Head relapping, new heads, width/format conversions, test tapes, demagnetizers
John French
249 Kennedy Road
P.O. Box 121
Greendell, NJ 07839
vox: 973-579-5773
fax:  973-579-6021

http://www.jrfmagnetics.com

IEM

International Electro-Magnetics, Inc.

350 N. Eric Drive

Palatine, Illinois 60067

Contact IEM by Telephone

Vox: 847-358-4622

Fax: 847-358-4623

Sales: -800-227-4323

http://www.iemmag.com/

MDI PrecisionMotorWorks
Jeff Gilman
241 White Pond Road
Hudson, Massachusetts 01749 USA
vox: 978-562-4420
fax: 978-568-1887
mailto: info@PrecisionMotorWorks.com
http://www.precisionmotorworks.com/

Media Tech / Northern Lights Audio

(Studer Specialists)
Ed Krupski
972 North Fifth Street
New Hyde Park, NY 11040
516-291-0281 voice
516-628-9028 fax

http://www.northernlightsaudio.com/

mailto: Vehicleone@aol.com

MAGNETIC REFERENCE LABORATORY, INC.

229 Polaris Ave, Suite 4

Mountain View, CA 94043

Vox: 650-965-8187

Fax: 650-965-8548

http://home.flash.net/~mrltapes/

RTZ Audio
(redesigned Ampex Electronics)
PO Box 872
Alpharetta, GA 30009
VOX: 770 346-9704
FAX: 801 681-3603
http://www.rtzaudio.com/

Sprague Magnetics

12806 Bradley Ave.

Sylmar, California 91342

Vox: 818-364-1800

Fax: 818-364-1810

http://sprague-magnetics.com/

TSI - Technical Services Inc. (Ampex parts Resource)
Vern Sauer
107 South Prindle
Arlington Heights, IL 60006-0765
847-392-2958 voice
mailto:lmsauer@ix.netcom.com