Impact On CPU Processing Power
Zipper Noise in Volume Automation
Clearing Track Routing on the Alesis BRC
Continuous Sync vs. Trigger Sync
The 1212 I/O can be expanded to up to 12 channels of analog input and output, by using external ADAT optical and S/PDIF analog-to-digital converters.
There are a growing number of 8-channel ADAT-to-analog converters on the market, including the excellent Korg 880A/D and 880D/A. Other manufacturers include Apogee, Frontier Design Group, Creamware, Lucid, MIDIMan, Mytek, and SoundScape (although some of these products are not yet shipping at the time of this writing). These products offer different combinations of features and quality at different price points, allowing the user to judge which is best for their needs.
The S/PDIF I/O can also be used for additional 2-channel analog input and/or output. A large number of S/PDIF-to-analog converters are available, at a wide variety of price points.
When "ADAT" is selected as the word clock source, the 1212 I/O uses the clock received via the ADAT optical connectors.
The 1212 I/O uses the 9-pin ADAT sync connection only for ADAT timecode, and not for word clock.
(It is possible to transmit and receive word clock through the 9-pin sync cable as well, and some systems do so - but the 1212 I/O keeps things simple and uses the optical cables instead.)
All bus-mastering audio cards, such as the 1212 I/O, work in basically the same fashion. The card reads and writes audio data directly to and from the main RAM, bypassing the CPU. This process is known as Direct Memory Access, or DMA.
This means that the CPU doesn't do much at all to make the audio I/O itself happen, although the DMA transfers do take up a very slight amount of bandwidth.
The CPU still has to do all of the normal audio tasks, such as dealing with the hard drive, mixing, effects, etc. Also, the more inputs and outputs you use, the more work the program's mixer has to do. Depending on the audio program being used, the work required to generate each output is roughly equivalent to playing back a single track from disk.
Some programs, such as Cubase VST, allow you to specifically enable and disable inputs and outputs, so that you can adjust the amount of processing power spent on the mixing process. Other programs, such as Digital Performer and Deck, automatically enable and disable inputs and outputs as necessary.
Because of the additional work required to handle additional inputs and outputs, one should expect to see slightly less CPU performance when using a multi-channel card (1212 I/O, AW8, etc.) than when using stereo audio hardware (AMIII, Apple Sound Manager with built-in I/O, stereo Windows soundcards, etc.). In general, the difference should not be very great - but with slower computers (such as the Apple 7200 series), using additional inputs and outputs may cause a noticeable difference in performance.
For specific information of CPU processing power and Digital Performer, see Digital Performer 2.4 features more efficient MAS.
The 1212 I/O operates as a PCI bus master. This simply means that it can take control of the bus, in order to transfer audio data to and from the computer's RAM. Multiple bus masters can coexist in a single system, as long as they leave enough time for one another to operate; this is why it is sometimes necessary to scale back video or SCSI acceleration. For more information, see PCI SCSI Cards, and Excessive PCI Message (Windows 95).
A frequently-asked 1212 I/O question is, "will the 1212 I/O work better in a bus master slot?" The quick answer is that it will *only* work in a bus master slot; fortunately, most recent computers, both MacOS and Windows 95, support bus masters in all slots.
On some early Windows-compatible motherboards, not all PCI slots supported PCI bus mastering. On these motherboards, it is necessary to make sure that the 1212 I/O is in a bus master slot; if the slot does not support bus mastering, the 1212 I/O will not work at all.
Modern Windows-compatible motherboards generally support bus masters in all PCI slots, so you should be able to place the 1212 I/O in any slot.
All Apple and PowerComputing MacOS computers tested by Korg support the 1212 I/O in all PCI slots. There are, however, some PCI slot issues with clones from Umax, Motorola, and APS, as detailed in Motorola StarMax & APS Clones and Umax S900, S910, & J700.
The 1212 I/O's features direct input-to-output audio routing, for zero-latency record monitoring. Some applications support only the direct monitoring (such as Deck II); others offer a choice between direct hardware monitoring and software monitoring (such as Cubase VST and Digital Performer).
Software monitoring allows you to route record inputs through effects plug-ins in digital audio software - for applying reverb to a vocal input, for instance. In general, however, software monitoring also adds a relatively large delay, which some may find distracting during recording. The actual amount of delay will vary depending on the audio software being used.
Direct hardware monitoring uses the 1212 I/O's built-in mixer to route audio directly from input to output. This is extremely efficient, and adds no delay to the monitored output. However, since this bypasses the main CPU, no effects plug-ins can be applied to record inputs. Effects plug-ins can still be used on playback tracks, as usual.
With most software, any input can be routed to any output for monitoring. For instance, ADAT 1-4 could be routed to Analog L, and ADAT 5-8 to Analog R. Note also that the direct hardware monitoring uses hard-panning only; it is not possible to pan a signal between a stereo pair.
For more program-specific information on record monitoring, click on the desired link below.
Record monitoring with Digital PerformerRecord monitoring with Logic Audio
The 1212 I/O serves as an audio input and output conduit for digital audio programs. It does not alter the audio data in any way. Specifically, it does not perform any volume control of audio to or from the digital audio program.
(The 1212 I/O does, however, control the volume of the direct input-to-output routing, for hardware record monitoring. This has no effect on audio recorded into or played back from the digital audio program.)
The 1212 I/O therefore will have no effect on the quality of volume automation. Any "zipper" noise, or lack thereof, is completely in the control of the digital audio program. Some programs cause zippering, while others are completely smooth and zipper-free.
The BRC's track routing features (under the BRC's Digital I/O button) control the digital I/O routing for the ADAT system. When copying tracks between ADATs, the BRC is used to select one or more source tracks on a single ADAT machine; this machine becomes the digital audio "transmitter," and the selected tracks are sent out on the optical bus. All the other ADATs in the system become audio "receivers," listening to the output of the transmitter and passing it on to their own outputs.
When using the 1212 I/O as the digital I/O source, all of the ADATs need to be receivers. If one of the ADATs is acting as a transmitter, then it will block the output of the 1212 I/O to all subsequent ADATs in the optical loop; it can also prevent the transmitter itself from receiving audio. This means that the 1212 I/O's output will not reach one (or all) of the ADATs in the chain.
To avoid this situation, you need to clear the BRC's digital I/O settings. To do this:
1. Press the BRC's EDIT button.
2. Make sure that the Digital Source is set to ADAT.
3. Press the BRC's DIGITAL I/O button until you see the "Select source with track buttons" page.
4. Make sure that no tracks are selected. If necessary, de-select any currently selected tracks.
If using the Alesis AI-1:
5a. Press the BRC's DIGITAL I/O button until you see the "Select tracks to output to AI-1" page.
5b. Make sure that no tracks are selected. If necessary, de-select any currently selected tracks.
5c. Make sure that the AI-1 Destination is set to ADAT.
Even if no tracks are selected, it is possible that one of the machines is still designated as a digital I/O transmitter - so continue on to the next step.
6. Press EDIT again to exit edit mode.
7. Press the DIGITAL I/O button twice, to toggle it off and then on again.
This ensures that the digital I/O settings have been reset, so that all of the ADATs are acting as digital audio receivers.
1. On the BRC, Press EDIT, then DIGITAL I/O.
2. Make sure that the Digital Source is set to ADAT.
3. Press the BRC's DIGITAL I/O button until you see the "Select source with track buttons" page.
4. Make sure that no tracks are selected. If necessary, de-select any currently selected tracks.
5. Next, toggle one track button for each of the connected ADATs, following the order in which the ADATs are connected on the sync chain (if the machines are toggled out of order, it does not seem to work).
6. Press EDIT again to exit edit mode.
Some games and multimedia programs require that the sample rate be set to 44.1kHz (or a sub-multiple, such as 22.05kHz). If the 1212 I/O is set to 48kHz, this may cause audio degradation. When using these programs with the 1212 I/O as the Sound Manager (MacOS) or Wave (Windows 95) output device, use the 1212 I/O Utility to set the 1212 I/O's sample rate to 44.1kHz.
The RealAudio Player requires that the sample rate be set to either 22.05kHz or 44.1kHz. When using the RealAudio Player with the 1212 I/O as the Sound Manager (MacOS) or Wave (Windows 95) output device, use the 1212 I/O Utility to set the 1212 I/O's sample rate to 44.1kHz. If the sample rate is set to 48kHz, the RealAudio Player will give an "Error 2: Out Of Memory" message.
Some digital audio programs offer a choice between two methods of synchronizing audio with incoming timecode: "continuous sync" and "trigger sync."
"Continuous sync" adjusts the timing of the audio to maintain synchronization with incoming timecode, using software interpolation. This can be useful when syncing to an analog tape deck, but it may sacrifice audio quality in the process.
"Trigger sync" means that the program will start each audio segment according to incoming timecode, and then allow the audio to progress normally, without using software interpolation to adjust the playback speed.
It may seem unintuitive, but when synchronizing a 1212 I/O with an ADAT system (or any other multitrack with digital I/O), the digital audio program should be set to "trigger sync." This is because the 1212 I/O already provides drift-free, continuous synchronization in hardware, through word clock synchronization via the ADAT lightpipe, S/PDIF, or word clock connection.
With trigger sync, the digital audio program will start playback of audio events at the appropriate SMPTE/MTC time, and then the 1212 I/O will take care of maintaining synchronization over the duration of the audio segment. Since the 1212 I/O's word clock is locked directly to the multitrack, the computer-based audio, external audio, and SMPTE/MTC-controlled MIDI tracks will remain perfectly synchronized.
In contrast, using software-based continuous sync will only serve to degrade the audio, and in some cases can even cause sync errors.
Note that it doesn't matter what type of timecode is being used; the rule is the same, whether the audio program directly supports the 1212 I/O's ADAT timecode, or if MTC or SMPTE are being used instead. As long as there is a digital connection between the 1212 I/O and the multitrack, you should always use trigger sync.
Trigger sync can be used whenever the 1212 I/O's word clock is synchronized to the master digital audio system. Any digital audio format can be used to carry the word clock, including ADAT optical, S/PDIF, or dedicated word clock cables.
The 1212 I/O can also be synchronized with Tascam DA-88 format multitracks by using any available digital audio connection, including S/PDIF, dedicated word clock, or ADAT I/O (in conjunction with a TDIF-ADAT converter).
When synchronizing to a video system, or to an analog multitrack, dedicated synchronizers (such as the MOTU MTP-AV and Digital Timepiece, or the Opcode Studio 64X) can be used to generate a word clock signal from timecode or video signals. This word clock signal can then be used to control the 1212 I/O, along with any other connected digital audio devices. Since this establishes a digital connection between the 1212 I/O and the synchronizer, trigger sync should be used in this case, as well.
Some programs, such as Deck II, use software-based continuous sync by default, and offer a specific parameter to switch to trigger sync. In Deck II, this parameter is called Trigger Sync; make sure that it is enabled.
In Cakewalk Pro Audio, the parameter which switches between continuous and trigger sync is called "SMPTE/MTC Sync," and is located in Settings->Audio Options->Advanced. This should be set to "Freewheel," which is Cakewalk's term for trigger sync.
If the program does not include a parameter to switch between trigger sync and continuous sync, then you can be confident that it is using trigger sync, and will provide drift-free lock between the 1212 I/O and an ADAT system.
PCI SCSI cards can provide greatly increased disk performance, resulting in increased numbers of playback and record tracks in digital audio software.
However, there is a catch: even though the bandwidth of the PCI bus is quite high, there are still limits on the amounts of data which can be transferred. Cards which transfer large amounts of data - such as PCI cards and video accelerators - may need to be scaled back if several cards are sharing the bus.
If there is not enough available bandwidth on the PCI bus, the 1212 I/O will not function properly. This will cause clicks and pops on MacOS systems, or "Excessive PCI Activity" warnings on Windows 95 systems.
The manufacturers of PCI SCSI cards, and other bus-mastering cards such as video accelerators, are aware of this issue, and generally allow the user to manage the amount of bandwidth consumed by the cards.
Korg has successfully used both MacOS and Windows systems combining the 1212 I/O, the Adaptec 2940 PCI SCSI card, and ultra-wide SCSI drives.
Adaptec includes software for configuring the 2940, named PowerDomain (for MacOS) and SCSISelect (for Windows). This software allows the user to set the data transfer rate individually for each drive connected to the SCSI card. On the MacOS, this feature is in the "Target Options" dialog; under Windows, it is in the "SCSI Device Configuration" section.
Note: MacOS users should install version 2.5 (or later) of the PowerDomain software.
On MacOS systems with a single PCI bus (all 3-slot desktop and mini-tower models, including 7200, 7500, 7600, 8500, 8600, G3 series, etc.), we recommend setting the transfer rate of audio drives to 10MB/sec; higher transfer rates may cause clicking in the audio, due to conflicts on the PCI bus.
On MacOS systems with two PCI buses (all 6-slot towers, including 9500, 9600, and PowerTower Pro), we recommend placing the 1212 I/O and the 2940 on separate PCI buses, so that each has the maximum PCI bandwidth available. If this is not possible, follow the instructions for single PCI bus systems, above.
On Windows 95 systems, the maximum transfer rate of 20MB/sec seems to work in many cases. If the "Excessive PCI Activity" warning appears (see Excessive PCI Activity message for more information), and adjusting settings for video cards does not solve the problem, try reducing the transfer rate of the 2940's drives to 10MB/sec.
Power Computing's PowerCenter Pro CPUs used a slight variant of the Adaptec 2940, named the 2930. As with the 2940, we recommend limiting transfer rates to 10 MB/sec. It may also be helpful to set the PCI Bus Mode (under Board->Video Settings) to "Cache Line," and select Secondary Interrupts.
The Macintouch website has more information on this issue, at http://www.macintouch.com/cubasepcc.shtml.
When using the ATTO Express PCI SCSI card, Korg recommends setting the transfer rate to 10 MB/sec, using ATTO's "ExpressPro-Tools" program. The latest version of this program may be downloaded from ATTO's website, at http://www.attotech.com/software/.
Some G3 Macintosh models are bundled with the ATTO Express PCI SCSI card. As above, Korg recommends setting the transfer rate to 10 MB/sec, using ATTO's ExpressPro-Tools program. This program is not included in the box, but may be downloaded from ATTO's website, at http://www.attotech.com/software/.
Korg does not currently recommend use of the Initio Miles PCI SCSI card with the 1212 I/O.