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dwiller
Posts: 29
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 Posted - Wed Jun 18, 2003 1:32 pm |
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I just got an Echo Mia installed on my computer last night. Immediately after installing I was seeing the noise level at -99 dB (average RMS) which was great. However, after plugging in my tape deck it jumped up and went higher again after simply powering on the tape deck. I don't have exact numbers at the moment but I think the noise floor is now around -70 to -80 dB which I guess still isn't too bad but I wish it was lower.
My setup is simply a consumer grade cassette deck hooked up to the computer described in my profile using cables with RCA on one end and quarter inch plugs on the other.
My questions are:
1) What can I do to get the noise level lower? The computer, cassette deck and other stuff in the room are grounded through the ground of the AC plug. Do I need to somehow ground the equipment differently.
2) Do I even need to worry about a noise level where it's at? I suppose considering the quality of cassette tapes I don't need a whole lot of dynamic range. On the other hand, some of the tapes I want to digitally record were not recorded high enough and I would like the lowest possible noise level so that I can amplify with Cool Edit Pro and not add a whole lot of perceptible noise.
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zemlin
Location: USA
Posts: 1156
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| Posted - Wed Jun 18, 2003 2:48 pm |
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If that's coming through your cassette deck I doubt you'll get any better than that - and the noise floor of the tape won't get near that so trying to improve it for cassette transfer would be pointless.
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SteveG
Location: United Kingdom
Posts: 6695
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| Posted - Wed Jun 18, 2003 3:05 pm |
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Yup, that's progress. The Mia is giving you a good indication of the output stage noise floor of your cassette recorder. As you say, it's a consumer grade cassette recorder, and the Mia is a professional-grade soundcard. And yes, I'd expect the Mia to be 30dB quieter than the cassette, which in fact sounds to be doing quite well!
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dwiller
Posts: 29
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| Posted - Thu Jun 19, 2003 7:30 am |
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I suspected such. Thank you for the information.
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dwiller
Posts: 29
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| Posted - Thu Jun 19, 2003 8:32 pm |
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I accept what you folks said before but it's really bugging me that my noise floor is so much higher with my cassette deck plugged in and turned on. The greater dynamic range of the Mia over my onboard sound was the primary motivation for upgrading to a Mia.
The noise floor is currently as high as -65 dB average RMS with the cassette deck connected and powered on. Part of that additional noise seems to be due to going through a Radio Shack source selector swithing box to allow for multiple inputs. Just having it running through the box (with no other inputs connected) adds 5dB or so. I will probably remove that from my set up and simply connect/disconnect the appropriate wires.
My question now is: Does cable quality (and length) have any effect on the noise floor? I'm wondering if there's any advantage to those high end, gold contact cables, or are they simply a waste of money?
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kylen
Posts: 290
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| Posted - Thu Jun 19, 2003 9:49 pm |
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| Quote: | | On the other hand, some of the tapes I want to digitally record were not recorded high enough and I would like the lowest possible noise level so that I can amplify with Cool Edit Pro and not add a whole lot of perceptible noise. |
Hi dwiller,
I think when you do what you say above that a -70db noise floor won't be as much of an issue for you as the tape noise. Just a guess based on what mine sound like.
I use Furman power conditioning (both AC regulation and balanced isolation) and sticking a good old tape deck thats simply turned on brings my audiophile 2496 noise floor up to about -70db or so. Depending on the tape deck I hook up the noise floor can rise higher.
You can try doing a little processing once you're done capturing your audio by adding a little downward expansion. If you're into outboard equipment there are RG expanders and DNF (Dynamic noise filter) you can stick in between the tape deck and the audio card. They were popular in the 80's and possibly you could find something for cheap.
The restoration or broadcast folks should have an idea about this too.
Ed. I forgot to mention I even tried a set of .5 meter monster cables, the kind that look like welding cables, and that helped the noise very little - maybe a db or so if that.
Good capturing! 
kylen
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AndyH
Posts: 1425
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| Posted - Fri Jun 20, 2003 12:43 am |
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Look at a recording of the noise floor with the Frequency Analysis. If there is much of a peak at 60Hz or 120Hz, and especially if there are many higher order harmonic peaks, you might be able to make some improvement with your input cables. However, unless your current cables are really bad, the improvment will come from changing the cables' routing between the cassette deck and the soundcard.
In my experience hum pickup can be markedly effected by things near the cables. Sometimes these things don't seem very likely as a source, but you should be able to figure it out by whatever happens when you move things around.
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