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  #1  
Old 2007-04-06, 04:27 PM
forkstriker4 forkstriker4 is offline
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RCA to XLR Conversion

I plan to transfer some cassette tape and VHS tape audio to my computer. However, as most may know, both cassette decks and VCRs typically only supply unbalanced RCA inputs and outputs. I plan to transfer this cassette and VHS tape audio using my PreSonus Firepod, and I would like to take advantage of its low noise XLR inputs.

I need to convert these unbalanced RCA outputs to match the balanced XLR inputs of my Firepod. How should I do this? There are several products that can do this, such as the ART Cleanbox RCA to XLR, the Rolls Matchbox II, and several high quality passive and very expensive Jensen transformers. Should I bother with making sure that the impedances and levels match between the connectors?

Any advice is appreciated.

Thanks.
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  #2  
Old 2007-04-06, 05:26 PM
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Re: RCA to XLR Conversion

the XLR inputs are for amplifying the very weak signal that comes from a microphone and carefully bring it up to line level inside the circuit. Since a cassette deck and vhs put out the desired line level already in order to properly "take advantage" of these XLR inputs you would have to run through a direct box which means it passes through a transformer which adds noise and dulls the highs a little. Then when it gets to the XLR inputs it would have to be re-amplified, adding some more noise, from your description a low amount of noise, but still more noise that is unnecessary. The only possible advantage to this is if you absolutely need to run more than 20 feet of cable.

If you avoid the direct box by just getting connectors to go from RCA to XLR then it will sound even worse than that.

The proper way is connect the outputs of the cassette deck/vcr to the line in inputs of the soundcard. Use a short 3' high-quality cable (get it at the guitar/music store, not at the buck store).

If you're not convinced, try hooking it up both ways, capture the same little stretch of tape twice in a row and give a listen. Who knows? Maybe adding a little noise and dulling the highs could take the edge off a cold digital recording.
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  #3  
Old 2007-04-06, 08:38 PM
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AAR.oner AAR.oner is offline
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Re: RCA to XLR Conversion

^^^like Five said...using a Firepod, run RCA>1/4" line in
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  #4  
Old 2007-04-06, 08:53 PM
forkstriker4 forkstriker4 is offline
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Re: RCA to XLR Conversion

Quote:
Originally Posted by AAR.oner
^^^like Five said...using a Firepod, run RCA>1/4" line in
Still... Would there not be issues with unmatched impedances with this? Would that not create more noise? What should be done about TS and TRS connections?

Also, cassette decks out there like the Nakamichi MR-1 have XLR outputs. Would that naturally provide a considerably lower noise source?

Thanks for the input, guys!
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  #5  
Old 2007-04-06, 09:54 PM
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Re: RCA to XLR Conversion

yes, the Nak decks with XLR outs would definitely be the way to go...but thats a whole helluva lot different than a consumer deck running RCA>XLR

if you can get yer hands on a good Nak, or any pro cass deck for that matter, do...as for the VHS transfers you mentioned in the first post, thats a different setup all together
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  #6  
Old 2007-04-06, 10:48 PM
forkstriker4 forkstriker4 is offline
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Re: RCA to XLR Conversion

Quote:
Originally Posted by AAR.oner
yes, the Nak decks with XLR outs would definitely be the way to go...but thats a whole helluva lot different than a consumer deck running RCA>XLR

if you can get yer hands on a good Nak, or any pro cass deck for that matter, do...as for the VHS transfers you mentioned in the first post, thats a different setup all together
Well then... Could you supply me with a more detailed method for the RCA to 1/4" jack conversion? I'm already capable of doing an RCA to 1/4" conversion, but isn't there more to it?

I have a stereo RCA to stereo 1/8" (3.5 mm) gold plated cable from Radioshack, and I think it is almost 3 feet long, and then I have a stereo 1/8" to to two separate 1/4" jacks (for the right and left channels) cable, which is not gold plated. I connect these two cables with a stereo 1/8" coupler, which also not gold plated.

What else do I need to know? Aren't there still impedance issues?
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  #7  
Old 2007-04-07, 11:12 AM
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Re: RCA to XLR Conversion

you should really pass on the RadioShack cables, better to spend a bit more and get decent quality:
http://www.bhphotovideo.com/bnh/cont...goryNavigation

there are much better cable manufacturers out there that i'd probly go with [Canare for one]...but thats about as affordable as it gets while mainting halfway decent quality

as for any impedence issues and what not -- a halfway decent cass deck [via RCA outs] > above cable > Firepod [via the 1/4" line ins] will give you good results
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  #8  
Old 2007-04-07, 12:38 PM
forkstriker4 forkstriker4 is offline
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Re: RCA to XLR Conversion

Quote:
Originally Posted by AAR.oner
you should really pass on the RadioShack cables, better to spend a bit more and get decent quality:
http://www.bhphotovideo.com/bnh/cont...goryNavigation

there are much better cable manufacturers out there that i'd probly go with [Canare for one]...but thats about as affordable as it gets while mainting halfway decent quality

as for any impedence issues and what not -- a halfway decent cass deck [via RCA outs] > above cable > Firepod [via the 1/4" line ins] will give you good results
I have always heard that this cable quality stuff is just a gimmick. Do you have an opposing view to that? I mean, I have experienced getting bad cables, but if a cable works, how is it different from any other functioning cable?

Has anyone done some kind of thorough analysis of this cable quality issue? Couldn't someone record the playback of a sample of something twice with two different cables, one "high quality" and one "low quality", while keeping all other factors constant (including cable length), and use a frequency analyzer on the two recordings to detect a difference? Maybe some other kind of better analysis could be done.

Thanks for your responses so far.
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  #9  
Old 2007-04-07, 12:46 PM
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Re: RCA to XLR Conversion

Quote:
Originally Posted by forkstriker4
Well then... Could you supply me with a more detailed method for the RCA to 1/4" jack conversion? I'm already capable of doing an RCA to 1/4" conversion, but isn't there more to it?

I have a stereo RCA to stereo 1/8" (3.5 mm) gold plated cable from Radioshack, and I think it is almost 3 feet long, and then I have a stereo 1/8" to to two separate 1/4" jacks (for the right and left channels) cable, which is not gold plated. I connect these two cables with a stereo 1/8" coupler, which also not gold plated.

What else do I need to know? Aren't there still impedance issues?
yeah, pass on the rs cables, don't worry about gold plated so much as the quality of the cable itself.

for rca > 1/4" just get a cable with two rca on one end, two 1/4" on the other... avoid adapers. Generally speaking, RCA and 1/4" will have matched impedance.

If you're using a deck with XLR out, it may or may not be matched... you have to try it. There might be some info in the specs, what the outputs are and what the inputs are. Sometimes pro stuff has XLR connectors that run at line level, actually its a little different than "consumer line level" (-10dB) in that case and the impedance will be off.

safest bet from what I can tell is rca>1/4", but try it a few other ways, whichever sounds the best is what sounds the best!!
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  #10  
Old 2007-04-07, 01:30 PM
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Re: RCA to XLR Conversion

Guess someone should add the comment that if possible to use a cassette deck with adjustable playback azimuth if playing back on a deck that the tape wasn't recorded on. This can make a noticable difference in audio transfer quality. The Nak MR-1 mentioned above doesn't have this feature (it does have pitch correction ability though).
Some decks can have the azimuth adjusted by a "poor man's method" of taking a screwdriver and turning the adjustment screw but this can't always be done...depends on the deck. There's instructions on the net if you Google.
The CR-7A allows manual adjustment and the Dragon is automatic to name two Naks with playback azimuth correction if you're into that brand.
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  #11  
Old 2007-04-08, 01:01 AM
forkstriker4 forkstriker4 is offline
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Re: RCA to XLR Conversion

I will take all of the above suggestions into consideration, if possible. I appreciate them.

However...

Does anyone else have anymore suggestions?
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  #12  
Old 2007-04-09, 12:47 PM
forkstriker4 forkstriker4 is offline
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Re: RCA to XLR Conversion

I forgot to mention something about the Firepod.

Its documentation claims that (from what I can remember) gain can be increased on files recorded through the mic preamps without increasing noise. This is most likely a gimmick (or incorrect/a misinterpretation on my part), but I thought I would put into consideration. Going directly from RCA to 1/4" inputs would still be the wisest way to go? I have one direct box, so I suppose I could try out this supposed feature...
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