User manual ALESIS EC2

[. . . ] EC-2 96kHz Sample Rate Upgrade A/D and D/A Converter Cards for the ADAT HD24 Hard Disk Recorder OWNER'S MANUAL VERSION 1. 0 APPLIES TO ADAT HD24 SOFTWARE VERSION 1. 05 AND ABOVE EC-2 96kHz A/D/D/A upgrade · appendix A © 2002 Alesis. Reproduction in whole or in part is prohibited. 7-51-0107-A 6/2002 Specifications Subject To EC-2 Manual appendix A EC-2 96kHz Upgrade Cards This document covers only those aspects unique to the EC-2 cards and should be kept with the HD24 manual. Table of Contents Important Safety Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Safety symbols used in this product . . . . . . . . . . . . . . . . . . . . . . . [. . . ] Place the Analog Input PCB in the top set of rear panel holes (labeled INPUT on the rear panel) with the components facing down and put a few of the washers and nuts on the 1/4" jacks to hold the PCB in place. Screw them down all the way, but do not tighten. 8 . Insert the ribbon connector labeled "J3 TO MAIN PCB" on the daughterboard into the 26pin header labeled on the main PCB as "J14 TO D/A PCB". The headers on the main PCB sit near the back center, where the old input/output PCBs used to plug in. The red side of each cable should face the right of the HD24 (closest to the fan). Verify that the cables don't have any twists in them and that there are no unconnected or exposed pins on the headers. Lay the daughterboard gently on the PCBs at the rear of the hard drive cages until the Analog Input and Analog Output PCBs are installed. Get the new Analog Output (D/A) PCB from its packaging. Remove the nuts and washers from the 1/4" connectors on the new Analog Output (D/A) PCB. HD24 with EC-2 installed Daughterboard PCB 1 Analog In A/D PCB 2 3 4 5 6 Analog Out D/A PCB New DC power cable EC-2 Manual A-5 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. 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). 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 appendix A · EC-2 96kHz A/D/D/A upgrade Synchronizing at high sample rates: To record more than 12 tracks in the high sample rate mode, simply synchronize two HD24/EC-2 units together by linking them with an ADAT Sync cable (see page 24 of the HD24 manual). Up to five HD24s may be synchronized this way, allowing high-sample rate systems of up to 60 tracks. Inputs and Outputs The inputs and outputs of the HD24/EC-2 are the same basic type as on a "stock" HD24: balanced 1/4" TRS jacks with a nominal +4 dBu level corresponding to ­15 dBFS on the HD24's meter. In most installations, there will be no difference in meter readings or levels after you install the EC-2. However, there is a slight difference in the balancing circuitry that may affect some installations. The EC-2 features true differential inputs and outputs, with dual drivers on each output instead of the more common (and less expensive) "impedance balanced" (sometimes called "ground compensated") method of balancing the outputs found on most audio gear (and on the original HD24 boards). As a result, if you plug the output of the EC-2 into an unbalanced input, the nominal output will be ­2 dBu, 6 dB less than if the EC-2 was seeing a true balanced load. This is normal operation and has no effect on the final quality of the sound. . . it only reduces the readings on the console's tape return meters. To avoid this 6 dB loss, simply plug the outputs of the HD24/EC-2 into balanced inputs on the console. Synchronizing two HD24s at different sample rates: When synchronizing multiple HD24s (or an HD24 with tape-based ADATs) together, it is possible to have an HD24 record and play back a high sample rate Song, while other machines play back a standard sample rate Song. [. . . ] When using it as an A/D converter, press the ALL INPUT button with INPUT SELECT set to ANALOG; when using it as a D/A converter, set INPUT SELECT to DIGITAL. Remember that for an input or output to be active, the current Song must be initialized for the proper number of tracks, even if you're not recording or playing back the HD24 itself. Latency Every digital conversion requires a certain amount of time, although the time delay involved is usually less than the time it takes sound to travel one foot through the air. However, if you have a digital workstation that allows compensation for input and output delays, see the Specifications section on page 13 of this manual for latency figures. In most cases, this is only critical when you're using different interfaces simultaneously (for example, the analog inputs of a computer interface plus its ADAT Optical inputs receiving the output of the HD24). [. . . ]