Firebox and S/PDIF

sleeper42

New member
Hey all... this may be a dumb question for some - I want to be able to use all 6 inputs on my Firebox. What do I need to get the signal from the mic into the S/PDIF ins on the the Firebox?

I imagine there's some kind of an converter box, preamp, or something? I can plug the mics into my board and use those preamps - but I guess I would need to go from there into "something" that has (left and right) 1/4in (or XLR) INs and S/PDIF OUT (left and right) Right?

Suggestions, and/or flames welcome... :)
 
SPDIF is basically for devices that outputs SPDIF signals for analog/digital conversion and many more uses. i don't have much idea about it myself so anyone correct me if i'm wrong.
 
sleeper42 said:
Hey all... this may be a dumb question for some - I want to be able to use all 6 inputs on my Firebox. What do I need to get the signal from the mic into the S/PDIF ins on the the Firebox?

I imagine there's some kind of an converter box, preamp, or something? I can plug the mics into my board and use those preamps - but I guess I would need to go from there into "something" that has (left and right) 1/4in (or XLR) INs and S/PDIF OUT (left and right) Right?

Yes. What that "something" is is an AD (analog to digital) converter.

Your mic puts out an analog signal (a little tiny, somewhat fragile, one). A mic preamp take that tiny signal and amplifies it into a more robust line-level analog signal. An AD converter takes a line-level analog signal, converts it into bits and bytes, and outputs a description of those bits and bytes in a code readable by other machines (S/PDIF, in this case, is the code or "format" the information is in).

S/PDIF is the most common format, either through an RCA jack or an optical cable. Though the RCA connector is the same as those commonly used for consumer audio, the signal is completely different. If you plug it into an analog input, it will sound sort of like angry bees. Really angry bees. Don't do that. Also, ordinary audio cables may not work for digital signals, because the signal is much higher frequency. You want to use "75-ohm" cables for connecting S/PDIF outputs to S/PDIF inputs. The S/PDIF format sends two channels (i.e. a stereo signal) together in one data stream.

AD converters are out there in various forms. They're in computer soundcards. There are standalone ones (some costing thousands of dollars, some very little). Lately, more manufacturers have taken to building them into preamps (like that ART box, I guess), or mixers.
 
sjjohnston said:
AD converters are out there in various forms. They're in computer soundcards. There are standalone ones (some costing thousands of dollars, some very little). Lately, more manufacturers have taken to building them into preamps (like that ART box, I guess), or mixers.

Thanks sjjohnston,
That's exactly what I needed to know. I figured I probably didn't NEED to buy another preamp to accomplish this task. I guess I just need to find an AD converter. Yeah, I see this functionality built into sound cards, but again... I don't need a soundcard - I have the Firebox. :)

Anyone have any suggestions on a piece of hardware that isn't a preamp that can do this? Maybe an EQ, or just a converter box?

Also, I gotta say, this forum has been a great help in me getting my little home studio up and running.
 
I think your best... and cheapest, option would be a preamp... Most format converters (of any decent quality) could easily cost more than an entire preamp, and offer less features and options. Stand alone A/D converter performance tends to range from marginal... to phenomenal... not much in the mid-price range that can't be matched in quality and costwith a pre of equal price.
 
sleeper42 said:
Anyone have any suggestions on a piece of hardware that isn't a preamp that can do this? Maybe an EQ, or just a converter box?
I won't claim to know the whole market, but there are a number of relatively inexpensive converters.

One inexpensive one I've seen (but not actually used) is the M-Audio Transit.
http://www.m-audio.com/products/en_us/Transit-main.html
I think its street price is something like 50 or 80 dollars. Its biggest selling point (other than price) is that it's very portable, if that's something you care about.

Companies like M-Audio and Edirol have a whole range of converters in different formats.

Other possibilities:
- "Vintage" (heh) converters on eBay, like, say, a Symetrix 620 (20-bit, 48k, but a quality product).
- Some reverb/multi-effects boxes (cf. Lexicon) have digital outs. Run it completely dry, and it's an AD converter. Plus, you can use it as a multi-effects box if you want.
- Any digital recorder which has analog ins has a converter in it somewhere. Some of them also have digital outs. This route, I think, is less likely to be worth pursuing, unless you're in the market for a DVD recorder or something. Otherwise you'd likely be either paying a signifcant amount for a recorder you don't want, or getting converters of questionable value (like in an old DAT or something).

I'll strike a slight disagreement with, perhaps, some others. The low-price standalone converters are almost certainly no worse than what's bundled into a low- or mid-priced preamp. The chip itself is probably the same. The surrounding electronics are likely either the same or a little better, if only because the converter gets its own separate signal path, power supply and box. There's a price (not a huge one, but still ...) for the separate box/power supply/circuit board. Sure, it's cheaper to throw a converter into an existing box with a preamp than to put one in its own box ... but if you don't have a driving need for another preamp, buying an extra box with the converter in it is still a lot more efficient than buying a whole extra preamp with the converter in it.

An $80 or $100 converter isn't as good as a $2,000 converter. But it's as good as or better than the $40 or $50 converter included with a value preamp.
 
One thing I just realized about the M-Audio Transit: its digital connections are optical. So it may not be a great idea if you've only got a coax (i.e. RCA) input. There are boxes which simply convert back and forth between coax and optical, but that's another $50 or so, plus another piece of equipment to fool with, and some more cables.
 
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