Using the EC-2, Connect the PCBs

EC-2 96kHz A/D/D/A upgrade • appendix A

Connect the PCBs

13.Connect the daughterboard to the Input and Output PCBs: Line up the connectors to the bottom (D/A) and top (A/D) PCBs, make sure all the pins line up, then gently push the daughterboard to the rear of the HD24 using the plastic ribbon cable headers as pressure points, making a connection between all three PCBs.

The connectors will only line up in one orientation. Verify that there are no pins unconnected or exposed.

14.Put the remainder of the washers and nuts on the jacks of the input and output connectors and tighten them all down (total 48 jacks).

15.Install the new DC power cable, connecting the power supply, main PCB, daughterboard, and hard drive PCBs as shown in the illustration on the previous page. Run it from the daughterboard to the main PCB to the power supply, then back from the power supply to the two drives. Make sure the connectors snap into place securely.

16.Replace the top panel.

To test for proper installation

After installation, you will be able to select ANALOG input as well as DIGITAL with SAMPLE RATE set to 88.1 and 96kHz.

1.Plug the unit back in to AC power and turn on the HD24.

2.Select or create an 88.2kHz or 96kHz song.

3.Press INPUT SELECT until the “INPUT” group in the alphanumeric display indicates “ANALOG”. This confirms that the HD24 has detected the EC-2’s presence.

If it’s not detected, unplug the unit and check all connections carefully, disconnecting and connecting each, then trying again to see if the EC-2 is detected. Contact Alesis Product Support or an authorized service center if the cards are still not detected.

Using the EC-2

For important information about high-resolution operation of the HD24, see Chapter 7 of your ADAT HD24 owner’s manual (page 65).

About 96kHz/88.2kHz Sampling Operation

An ADAT HD24 with EC-2 upgrade boards installed operates identically to a “stock” HD24 with respect to input arming, selection, and routing (or “normalling”). The only difference is that you will be able to use analog inputs and outputs when the system is set to 88.2kHz or 96kHz sampling rates. (Without the EC-2, you must use the ADAT Optical digital inputs and outputs with an external 88.2/96kHz converter to record at higher sample rates.)

•About 12-channel operation at high sample rates

When recording and playing back any Song that has been initialized at the 88.2 or 96 kHz sampling rates, the HD24 is limited to recording a maximum of 12 channels.

•Analog input channels 13-24 will be ignored.

•Analog output channels 13-24 will duplicate output channels 1-12.

•Digital inputs and outputs are grouped in fours instead of eights: tracks 1-4 on the HD24’s ADAT OPTICAL 1-8ports, tracks 5-8 on the HD24’s ADAT OPTICAL 9-16ports, and tracks 9-12 on the HD24’s ADAT OPTICAL 17-24ports. For more on operation of the ADAT Optical port, see page 66 of the HD24 manual.

When using an HD24/EC-2 at the standard 44.1kHz or 48kHz sampling rates, you will still be able to record and play back all 24 tracks. The only difference from the original boards will be improved audio performance, due to the higher quality converters and analog circuitry of the EC-2.

A-6	EC-2 Manual