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Old 12-13-2011, 10:10 PM   #11
GrassValley_BH
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Wow, that was quite informative, I learned a lot! Thanks!! :)
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Old 12-13-2011, 11:19 PM   #12
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Quote:
Originally Posted by dpalomaki View Post
Another concern with "Y" adapter splitting is possible interaction between dissimilar inputs; e.g., some sound card inputs may have a DC bias voltage on them that could cause a problem for an input on another piece of gear.
I definitely agree with that. I never feed an audio signal directly into a sound card. I either go through a mixer or preferably I use a USB audio interface to bypass the sound card altogether and do the A/D conversion outside the noisy environment of the computer. However I'm assuming the ADVC devices are better than cheap and nasty sound cards.

Ken.
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Old 12-14-2011, 02:03 PM   #13
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A few years ago there was a web site devoted to sound card tests, very rigorous tests that looked at frequency reponse, noise levels, IH and IM distortion, etc. (I think it has gone inactive since then.) The results were very interesting. Many sound cards were, honestly, quite dog meat, suitable for speech on poor speakers but not music. But some, were very good even in the PC case environment. A lot depends on the board construction and what is installed in the adjacent slot. There was a reasonable coorelation between cost and quality within a given product line, generics and mass-market products did not do as well.

An external AD does not guarantee quality, but it can make it a bit easier to control the external electronic noise environment. And noise sources can be unpredictable; e.g., I recall a few years ago that some specific camcorder batteries induced additional noise into the DV audio stream in certain camcorders, and using certain types of A/C power adapters can also induce noise under certain conditions.

There is no substiture for having a good kit of audio adapters such as ground lifters, isolation transformers, etc.

Radio Shack sells a ground loop isolator (stereo isolation transformer with RCA connectors) in their auto audio product line that I've occasionally found helpful when dealing with consumer electronics. Catalog #: 270-054
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Old 12-14-2011, 02:50 PM   #14
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Keep in mind that the low grade transformers also affect the frequency response quite a bit.
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Old 12-15-2011, 11:25 PM   #15
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using certain types of A/C power adapters can also induce noise under certain conditions
I remember once getting audio noise (hum) while using my ADVC-300 to digitise a VCR tape. I couldn't understand why as I had no power leads running alongside the audio leads. I then realised it was the ADVC-300's power pack which I had left sitting on top of the VCR player and it just happened to be in exactly the right spot to induce noise into the player's audio circuitry. If I moved the power pack a few cm in any direction, even though still on top of the VCR, there was no longer any noise. Needless to say I moved it well away, onto the floor!

Ken.
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Old 12-16-2011, 01:11 PM   #16
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Keep in mind that the low grade transformers also affect the frequency response quite a bit.
Amen! And audio transformers designed for mic level may not perform as well with line level signals, they may not perform well if used with circuits that have impedances that are substantially different from the transformer's design point, and of course transformers can pick up stray magnetic field noise if not well shielded so positioning and orientation can be important.

Some prower supplies are switching-based (not transformer) and may not provide full isolation frm the power lines. They also may have a very electrically noisy output.

There is no real substitute for using the right gear or for quality components.
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Old 12-19-2011, 10:42 PM   #17
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Yup yup! Despite trying to minimize cable distance, sometimes you need the distance. back in the day when TVs had tops big enough for VCRs to sit on them, because would put their VCRs on top of the TV, and they'd get "bonus" interference.
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Old 12-20-2011, 12:14 AM   #18
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...back in the day when TVs had tops big enough for VCRs to sit on them,...
And stray x-ray emissions from the picture tube (caused by too high second anode voltage) would zap the cat sleeping on the warm set.
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Old 12-20-2011, 12:56 AM   #19
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Holy moly, I just re-read my post and it's missing all sorts of words I had intended to type... Hahahaha, but you got the picture anyway. So great, the human mind.
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Old 02-05-2014, 09:53 AM   #20
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regarding of what's been said here, this card has an audio problem.
if i capture the same video tape, with the same video deck, in pinnacle i have the sound normal, clear, and with canopus i have lower sound (around 30%) with a constant background noice becouse of that, wich of corse is increased when i rise the volume level on edit. the same observation is confirmed by looking at audio histogram wich with advc110 is flat and with pinnacle i have a normal histogram.

so, anyone from grass valley, do you have a fix for this bug?
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