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Keyboard FAQ
What kind of cables can I use between my QS Synthesizer and my computer?
PC-to-QS Serial Cables
The interface cables are either type Din8 to DB9 or Din8 to DB25. These are available from computer retailers or through Alesis Parts. The DB9 is used by most laptops, DB25 used by 80% of regular PCs. The DB9 to DB 25 adapter (needed for some computers to attach to our cable) is easily found at most computer stores.
Macintosh-to-QS Serial Cables
This is just a regular printer cable, DIN8 to DIN8, available from any Apple Computer retailer, or through Alesis Parts.
Serial Driver Software for PCs
In addition to our own driver (available from Alesis and found on the CD-ROM which ships with QS Synths) the PC SERIAL driver from Korg and Roland's Sound Canvas will work with the QS. This software simply tells the PC to look to its SERIAL port for MIDI info. It doesn't care what's on the other end.
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ADAT FAQ
Tape & Heads
What kind of tape should I use in ADAT?
ADAT is designed for Super-VHS (S-VHS) video tape. These look the same as regular VHS tape cartridges, but the tape itself has a higher density of magnetic domains, allowing digital information to be recorded and played back more accurately. At the store, look for the SVHS logo. Another clue: in the U.S. the tape length will be shown as "ST-120" or "ST-180", NOT "T-120". Similarly, in Europe, tapes will be shown as "SE-160", etc., not "E-160". Tapes marketed directly for ADAT may say something like "D40" or "D60" instead of "ST-120". Don't use plain VHS tape in an ADAT-it will have a much higher error rate than S-VHS tape.
How long does it record?
An ST-120 tape, which can record 120 minutes of video at the standard speed, will record just over 40 minutes on an ADAT. You can also use a long-playing ST-180 tape which will record over 60 minutes. ADATs are designed to handle both types, but the ST-180 costs more per minute because its base film is more expensive (so it can be thinner, but just as strong). If you don't need more than 40 minutes, get the ST-120. There's no advantage to getting shorter lengths, but they will also work. In any case, use the same length of tape in each machine in a multi-ADAT setup.
What brand should I use?
Alesis currently packs a BASF tape with every new ADAT. BASF is a high-quality brand with strong professional support and we're glad to be associated with them. They also make a pre-formatted ADAT tape available which costs a little more, but saves time and keeps your heads cleaner.
Several other companies also make very good SVHS tape such as HHB, Maxell, Sony, TDK, and Quantegy. Some have made packages especially designed for the ADAT user. In any case, we strongly recommend that you buy your tape in a hardshell storage case if one is available. That will keep the tape cleaner and more stable when you put it on the shelf.
How long do ADAT heads last?
It all depends on what kind of tape you use, how many new tapes you go through, and what kind of care you take of your ADAT. Having said that, they last a very long time in most cases, longer than video or DAT heads. They are warranted for one year or 1,500 "drum-on" hours (time when the heads are actually against the tape), but we've seen cases where heads lasted well over 6,000 hours. (To see how many hours have been logged on an ADAT, hold SET LOCATE and STOP.) Many heads are replaced by service centers not because of wear, but because an amplifier chip inside the head failed. And, replacing a head is not difficult for a trained technician with the proper tools and test equipment…but it is not a do-it-yourself job.
How often should heads be cleaned?
In most environments, we recommend cleaning every 250 drum hours. However, heads can get clogged immediately by a dirty tape or some other problem.
ADAT Optical Interface
How many bits are on ADAT Optical?
The ADAT Optical interface has always been 24-bits linear per channel, times 8 channels. In products that are 16 or 20-bit, the least significant bits are simply set to zero.
Can I get longer cables?
Yes, but I try to keep them as short as possible. The Alesis Parts Department sells cables in three lengths, which are also available at many Alesis dealers:
| 01 |
Optical Cable 1 Meter Fiberoptic |
20.00 |
| 0A |
Optical Cable 0.6 Meter Fiberoptic |
14.99 |
| 0C |
Optical Cable 5 Meter Fiberoptic |
35.00 |
Since ADAT cables are the same as those used for optical S/PDIF, you may be able to find them from other sources. The ends are called "Toslink" connectors. Technically, this is a Toshiba TOCP172 or equivalent, conforming to EIAJ standard RC-5720. The cable itself is plastic (PMMA), 1 mm diameter. While 5 meters is the recommended maximum for ADAT, there are reports of successful operation with cables up to 50 feet long, when all components are clean and operating at maximum efficiency.
For even longer runs, some people have used glass cable instead of plastic, as long as it is fitted with a Toslink connector. Glass has a thinner diameter, but it has less transmission loss. Try it before you buy it. For critical installations, the M20 may be modified with optical send/receive parts that are specifically designed for glass cables.
Hooking to Other Equipment
What happens when I connect a 24-bit device optically to a 20-bit (or 16-bit) ADAT?
Practically speaking, there's no perceptible change to the audio quality. While an ADAT can't record the lowest four bits, the fact is that those LSBs (Least Significant Bits) represent the noise of the A/D converter itself, not valid audio signal. It's like going to the gas station and trying to pay in tenths of a cent: they may exist in theory, but when you hand over the cash, it has to be rounded to the nearest penny anyway.
What about dithering a 24-bit signal down to 20-bit?
Unless the 24-bit signal was entirely artificially generated, dither isn't necessary. If it was ever an analog line-level (and certainly if it was a microphone) signal, there's more than enough noise in the signal itself to dither the signal.
What about dithering an ADAT's 20-bit output to a 16-bit ADAT or other device?
A Type II ADAT can output either 20, 16, or 16 bits with dithering. Set your XT20 or LX20 to "16dt" mode for the best quality audio when transferring to a 16-bit system. This will make it sound almost as good as the original 20-bit signal.
How can I digitally connect from ADAT to an AES/EBU device?
The Alesis AI-1 was originally designed for this task, but was discontinued because it was only a 16-bit device. But if you're going from an original Type I ADAT to another 16-bit device, it works fine. The M20 ADAT has an optional AES interface with four sets of AES/EBU input/output. Several companies make ADAT-to-AES converters:
Kurzweil DMTi
Otari UFC-24 (24 channels; requires the AES option board)
Yamaha digital mixers
The MOTU 2408 has multiple ADAT I/O and multiple output options. Contact MOTU for details.
Error Messages
What does "Er 7" in the ADAT display mean?
An Error 7 indicates that the ADAT is having trouble reading the information that keeps things on track (technically, the Write Timing Marker). This is generally caused by dirty heads or worn or damaged tape. If it is only happening in particular locations a particular tape, the indication would be a problem with that tape. If it is happening on many tapes, including newly-formatted tapes, the problem is likely to be dirty heads. For more information about this, see the ADAT Head Cleaning Tech Note.
What does Er 9 mean?
Er 9 Indicates that the ADAT is trying to play, but no tach pulses are being seen from the takeup reel. At this point, the ADAT will stop and go back to mode 1 (disengaged). If it weren't for Error 9, tape would continue to spill into the transport even though it wasn't being wound onto the reel.
A technician should verify that no slippage is occurring on the idler wheel as it tries to move the take up reel in Play mode. Replace the idler wheel and clean the edge of the reel table. The problem is often solved by cleaning or replacing the idler wheel, which is an inexpensive part available through Alesis. For instructions, see Idler Wheel Replacement. Another possibility is that the small belt that goes from the reel hub to the tach counter is broken or slipped off.
If this does not solve the problem, the ADAT would need to be serviced because there may be a problem with either the capstan motor, the reel motor or hall sensor.
My ADAT displays "ERR 2" and then ejects the tape. What does that mean?
ERR 2 means that your ADAT is having a tape threading problem. When a tape is loaded into the ADAT and threaded into the tape path, a device called a mode switch conveys the position of the thread arms to the software. Usually, an ERR2 problem is the result of a worn or dirty mode switch. Eventually this problem will increase in frequency until the unit will no longer accept a tape. The reason is because the software will eject the tape if it does not think the thread arms are where they are supposed to be when threading to avoid damage to the tape. The switch should be serviced by an authorized technician at Alesis or an authorized service center.
My original Adat say "Prot" when I insert a tape and will not allow me to record. The protect tabs have not been broken out of the casette. What is wrong?
The Protect Switch can be damaged if a tape is not inserted properly. It's bent, and thinks that the tape is write-protected. (To avoid this problem in the first place, always make sure that the tape is inserted straight, with a light pressure.)
With current ADAT software, you can defeat the Write Protect Switch by holding Set Locate and Track Enable 2 after you insert a tape. The display will read "PrOF" for a moment. This needs to be done each time you insert a tape for recording until you have the Protect Switch repaired.\
For a complete list of error messages and what they mean, see your ADAT manual.
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