d8b Database

d8b forum contributors

Anyhorizon, Dan Worley, SteveT, Mike Rivers, Reynolds Audio and the Forum Crew

Aux send 16 bit bug - Digital Out - Alt I/O

Courtesy: ReynoldsAudio


A bug has been found that occurs whenever an Aux send is assigned (Windows menu>Setup>Network) to one of the Alt I/O card outputs containing one of the digital cards (OPT-8, DIO-8 or PDI-8).

With this configuration, the output from the auxilliary sends will be truncated from 24 bits to 16 bits.

For most applications (FX send/return), the resulting 96 dB dynamic range will not create an audible difference in your mix.

A work around, if necessary, is to Pre DSP insert the Aux send into any of channels 1-48, assign that channel to a Bus and then assign the Bus to the Alt I/O card output.

If you are using the Alt I/O card outputs to transfer tracks digitally, routing through a Bus rather than an Aux will maintain 24 bit status.


Bit rate/wordlength - Answers for all I/Os

Courtesy: Dan Worley and Mike Rivers


Is it 16-bit or 24-bit?

What's coming in? What's going out? And why it may not be what you think.


All inputs are 24-bit. All A/D converters are 24-bit.


The Digital-1 (AES) and Digital-2 (S/PDIF) inputs are 24-bit, but the card uses 4 bits to do real-time sample rate conversion which rounds the signal down to 20-bit. Real-time sample rate conversion is always on for these inputs. You CANNOT turn it off. Consider the stock Stereo AES/EBU and S/PDIF inputs to be 20-bit.

The PDI card: The PDI card has real-time sample rate conversion which can be turned on or off (by you) as needed for each input pair (1-2, 3-4, 5-6, 7-8). When on, the 24-bit input signal will be rounded down to 20-bit. When it's off the signal will stay 24-bit.

Why would you want to turn on sample rate conversion? You would want it on if you had a DAT, CD player, sampler, or any other digital device hooked up to any of the PDI input pairs and their sample rate didn't match the d8b session. For instance, if you were working on a
44.1K session but you had some 48K audio on a DAT that you wanted to bring into the session. Or if you were working on a 48k session and wanted to bring in some 44.1k material from a sampler.

If you want 24-bit for any of the PDI's input pairs, make sure sample rate conversion is off. You can access the controls from the Setup > Digital I/O page.

DIO8 Cards: If you have old DIO8 cards, you should check their EPROMs to insure that they are 24-bit. The DIO8s first shipped with 16-bit EPROMs. If the EPROM says "ver 2" or above then it is 24-bit. Mackie will ship you 24-bit EPROMs if you need them. To date, they do not charge for the EPROMs, but that may change and they may charge you for shipping. If you purchased a used d8b with DIO8 cards installed, or purchased some used DIO8 cards, you should check to make sure the EPROMs are up to date. All you have to do is remove the cards and look at the paper label on the EPROMs. Who knows how long they were on the shelf before they found their way to you, or if the party you purchased your board from performed any upgrades.


All outputs are 24-bit. All D/A converters are 24-bit.

If you have UV22 activated for any of the Tape Out banks or Digital Stereo outputs (you do this from the Setup > Digital I/O window), then those outputs are still 24-bit but will have dither added to the eight least significant bits. Use UV22 on the tape outputs only if you're tracking to a 16-bit recording device. Use it on the stereo digital outputs if you're mixing to a 16-bit device, or if you're mixing to a 24-bit device and know you like the sound of UV22 better than any other dithering options you have. If that's the case, mix to the 24-bit device using UV22 on the d8b's outputs and truncate it from the 24-bit device for the final 16-bit mix.

The other exception is a bug which Mackie either couldn't fix or decided it would cost too much to fix: If you are outputting any of the Auxes from a digital card (DIO8, OPT8, PDI) in the ALT slot, those outputs will be truncated to 16-bit. That's for the Auxes only. Anything other than the Auxes routed out from the digital cards in the ALT slot will be 24-bit. If you route the Auxes out from any other slot other than the ALT slot they will be 24-bit.

Version 3 OS Bug and Patch:
If you're using the V3 operating system, be aware that the d8b will only output 16-bit from its outputs if Level To Tape is set to unity. Any setting other than unity (plus or minus) will result in 24-bit output.

Good news! There is a patch which fixes this bug. You can download it from here (look for the red type). The patch is for build 224 of version 3.0. It may work with previous versions but has only been tested and approved for build 224. This Level To Tape 16-bit bug may have been
present since Version 1.

There is no way to tell whether or not the patch is already installed by looking at any screen information. So if you're in doubt, download it and install it, the installer will tell you if the patch is already present.


Control Room Balanced Out to Amp Unbalanced In

Courtesy: The Forum Crew

If you run balanced cables from the C/R Main outs or Nearfield outs to an amp that has unbalanced ins and tie cold to shield or leave it floating, you will experience bleed. That is, the C/R monitor pot will not fully attenuate the signal when completely anti-clockwise. This is also true of the Studio out. The only solution is to use an amp with balanced inputs or buy a box that accepts balanced ins and converts in an active manner to unbalanced outs and place it at the amp end.


Digital In 1 & 2: Monitoring Anomaly

Courtesy: anyhorizon


If, when you first boot the d8b and with signal present at the SPDIF input, select Digital In 2 (SPDIF) and nothing can be seen or heard, select Digital In 1 (AES). You will then see and hear signal. Re-select Digital In 2 and everything will continue to be as it should until the next boot.


Digital In 1 & 2: Routing to Studio Output

Courtesy: Dan Worley

To get Digital In-1 to the Studio output, select Control Room as the source in Phones/Cue Mix-1 and turn up its V-Pot, plus the Studio V-Pot (they're linked together). The same is true for Digital In-2, except that it's linked to Phones/Cue Mix-2.


Stock Digital Input Limitations

Courtesy: ReynoldsAudio

The factory AES and SPDIF digital inputs on all d8bs are limited to twenty bits. The remaining bits of a 24 bit signal will be truncated.

Further, all incoming audio will be subject to sample rate conversion to the current d8b setting, even if it is consistent.

The reasoning for this was to provide a convenient connection for 16 bit DAT recorders and CD players widely in use at the time of the d8b’s design.

These inputs cannot be directly routed to tape outputs or to busses, auxes or DSP. The workaround is to pre-DSP insert the selected digital input to a pair (normally linked) of channels 1-48, allowing assignment to tape outs, busses, auxes, and application of plugins, channel EQ and dynamics.

The only way to input a 24 bit digital signal to the d8b is through one of the digital cards (OPT, DIO, PDI) in one of the I/O slots.

The stock AES and SPDIF digital outputs are 24 bits.


Abnormal Channel Behaviour: A Remedy

Courtesy: ReynoldsAudio

If you experience weird channel behaviour like levels and meters maxed out or not working or not showing up at all when you know everything else to be as it should (including the Master L/R) or if you are having issues with your tape I/O cards showing up intermittently, you can try a couple of things that don't require a reboot.

  1. Turn down your monitors.
  1. Under Windows>Setup>Digital I/O, try toggling the wordclock speed between 44.1 and 48 and then back again.
  1. If you have DIO-8 cards installed, under Windows>Setup>Digital I/O, for the card you are having trouble with, change the ins and outs from ADAT to TDIF and back again or vice-versa.
  1. Try toggling any of the parameters in the Digital I/O window.



DIO-8 Card LED Status

Courtesy: makski

The LEDs on the DIO-8 card indicate some useful information.

LED 1: Status of clock to card

a) If solid, the card is receiving sync, either internal or external w/c.
b) Will flash at medium speed if the board is set to receive external w/c, light pipe is connected but w/c signal is not present.
c) Will flash at fast speed if the board is set to receive external w/c, word clock is present but there is an internal fault and the clock can't lock to the w/c.

LED 2: Indicates that internal clock sync & lightpipe-->DIO are synced.

LED 3: Indicates that external clock sync & lightpipe-->DIO are synced.

LED 4: Lit unless lightpipe-->DIO exists (in other words, when lightpipe is connected to the input of the card, the LED goes out).

LED 5: Not used.

LEDs 6 & 7: Power indicators.