ULN-2

From MH Wiki

The ULN-2

Monitor gain

On the ULN-2, all monitor controller gain is in the analog domain, and you can adjust the maximum level via the front panel knob for the monitor outputs.

Save-States

There are 9 additional alternative boot states stored in the [ULN-2], and 8 alternative boot states stored in the [ULN-8].

They are accessed through the front panel up and down buttons. To store a boot state to the hardware, open MIO Console App and

Menu>Utilities>Save BootState x

(X= bootstate number corresponding to front panel button number)

Safe-Boot Mode

When you safety boot the [ULN-2],

hold the the 'up arrow' button (there is no dim button on the [ULN-2])

ULN-2 Conversion

The AKM 5383 is a 108 kHz 24-bit ADC, used in both the [ULN-2] and [2882]

The AKM 4393 is a 96 kHz 24-bit sigma-delta DAC, used in both the [ULN-2] and [2882]

These are both stereo chips, so the [ULN-2] has one for input and two for output, while the [2882] has four of each of them for the main analog I/O plus an additional DAC for the cans. The [ULN-8] has 8 of each, plus a DAC for the cans.

depending upon the sample rate, these AKM converters run at 128x oversampling – which happens to be the same rate as SACD. The DACs also have an 8x digital filter inside.

SRC in the [2882] and [ULN-2] use a Cirrus Logic CS8420 Digital Audio Sample Rate Converter which runs at 108 kHz and 24-bit for real-time SRC.

ULN-2 Analog Stages

Both the [ULN-2] and [2882] use the Excalibur low-noise high-speed JFET-input op-ampsfrom Texas Instruments,

and the [ULN-2] adds Burr-Brown OPA 2228 op- amps for high precision and low noise in high-gain situations.

Power Requirements

The minimum pre-regulation voltage is 9V.

The Maximum preregulation voltage is 33V.

At 12 Volts the current demand is:

[ULN-8] : 3-3.5A

[2882] High Power Mode 1.5A

[2882]: Low Power Mode 1A

[ULN-2] : 0.75A

A custom [jump boot] device can be be built with a pair of 9V batteries. It is used to power-on the MIO if the inrush current is too high for some macbooks to power the MIO properly.

Both the [2882] and [ULN-2] can be bus powered, the [ULN-8] will pass bus power, but does not provide it. (it also must be connected to a computer to power a MIO downstream)

DI Input

the TRS on the Combo Jack is 200K, which is pretty Hi-Z and would be a good DI.