The optical TOSLINK out is S/PDIF, just light instead electricity. The
TOSLINK module converts it from light pulses back into an electrical signal. Standard S/PDIF signals are ±500mV(peak to peak). The TOSLINK module outputs TTL-level S/PDIF, at 0-3V.
Most DAC chips utilize
I2S (Inter IC Sound) inputs. In order to convert the S/PDIF signal to I2S, you need to use an S/PDIF receiver of some sort, such as our
Tranceiver or
MUX modules. All of our DACs (Opus, COD and Buffalo) accept I2S. The Buffalo is unique in that it also accepts S/PDIF directly, so you do not need a separate module. If you need to support more than one S/PDIF inouts, the MUX allows switching between up to four, and outputs either S/PDIF (for longer runs) or I2S to go directly into a DAC. Incidentally (and not really applicable to your situation), the Transceiver module can accept S/PDIF and output I2S, or accept I2S and output S/PDIF, which makes it a great option for adding an S/PDIF output to a digital source that does not have one.
For simplicity's sake, there are two types of DAC outputs, Voltage and Current.
Opus is a Voltage output DAC, meaning it can directly drive a high impedance stage, such as a preamp or amp (with input Z >2Kohm or so). You can also utilize an output stage to improve it's performance by utilizing the DACs differential outputs.
COD is a current output DAC, meaning it outputs varying current rather than varying voltage. You need a separate stage to convert the current to voltage, and there are many ways to do this. The simplest means of doing this is to pass the current across a resistor to create a voltage (V=IR). You can also use transformers. We sell the
IVY (now the third generation IVY-III) and soon the Legato. Both of these stages do a very good job of I/V conversion, and output both balanced and single-ended (RCA) signals. the IVY uses fullly-differential opamps (not typical) and the Legato is fully discrete.
The Buffalo is, again, a special case. It is technically a voltage output DAC, but by presenting it with a near-zero impedance, acts as a current output DAC. Doing this allows it to perform at it's best. There is a lot of confusion about how to implement this out there, but basically, you want the I/V stage to have a near-zero input impedance. Both the IVY and Legato have an input impedance in the mili-ohm range. Note: You cannot use the simple resistor I/V methos with the Buffalo the same way as you would with a true current-output DAC, as it is not technically a current-output DAC, it just acts like one when driving a near zero impedance.
From the output stage, you can drive your amp or whatever. For volume control, we offer two solutions: digital and analog. For digital volume, there is the
Volumite, which uses the DAC's internal digital volume control (except for COD, which does not offer a software mode). This is a very good way of controlling volume, as there are no inter-channel irregularities and no resistor (Miller) noise added to the signal. The
Joshua Tree is our analog volume control solution. It has a varying input impedance (averages around 10-Kohm) and a fixed output impedance of 750R. It is meant to be used AFTER your output stage, and present a nice low output impedance to your amplifier with an input impedance of >7.5Kohm (most everything).
Hope this helps.
Edited by user Saturday, June 19, 2010 7:23:43 AM(UTC)
| Reason: Not specified
