During capturing some VHS tapes the unbalanced red and white audio RCA stereo coming out the VCR and going into the BrightEye75 pro capture device which is equipped with balanced Phoenix style connector audio input (see photo), I've noticed that some tapes have very low level even with the gain cranked all the way up in the BrightEye75 audio menu I still have the level below -10db in the capture app.
The hookup instructions for the BE75 recommends connecting the cold and ground to the ground side of the unbalanced and the hot to the positive side of the unbalanced side, this still produced low level, what is the easiest way to boost the level by 6db without an external box that requires too many cables.
Will these gizmos work without sacrificing the quality? and how to power them up?
The hookup instructions for the BE75 recommends connecting the cold and ground to the ground side of the unbalanced and the hot to the positive side of the unbalanced side, this still produced low level, what is the easiest way to boost the level by 6db without an external box that requires too many cables.
Will these gizmos work without sacrificing the quality? and how to power them up?
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The headphone idea is a good one, and costs $0.00. The 'gizmos' will work fine, but you'll still need a bipolar (+/- 15 volts) supply, and a case. The 'gizmos' show NE5534s for two of the opamps---these are EXCELLENT for this task. I don't know what the hell the other two are, though......and remember, any audio device can only be as good as its power supply.
It doesn't have a headphone output.
So If I use the one in the link is there a way to convert a normal 12V DC to bi-polar? or I have to start from AC and use a transformer and special bi-polar AC-DC rectifier?
So If I use the one in the link is there a way to convert a normal 12V DC to bi-polar? or I have to start from AC and use a transformer and special bi-polar AC-DC rectifier?
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There is no specification for gain for the gizmos. They could be unity gain, +6dB or +14dB, or anything else for that matter.
It is better not to common the ground and (-) on the balanced input as this may cause a ground loop that induces hum, so the ground of your unbalanced output should connect to (-) only. This has no effect on level matching; for that you need some more gain.
I solved a similar problem from my TV line out with an inexpensive stereo line preamp (booster) that runs on 12 volts single ended supply and has variable gain up to 15dB. It doesn't produce a balanced output, but that is not important for your setup, just wire the preamp output ground/shields to the (-) input terminal only as above. This is the one I used (price is $AU):
Pro1327 Stereo Audio Line Preamp with Gain Control 0-15Db | KG Electronic
It is better not to common the ground and (-) on the balanced input as this may cause a ground loop that induces hum, so the ground of your unbalanced output should connect to (-) only. This has no effect on level matching; for that you need some more gain.
I solved a similar problem from my TV line out with an inexpensive stereo line preamp (booster) that runs on 12 volts single ended supply and has variable gain up to 15dB. It doesn't produce a balanced output, but that is not important for your setup, just wire the preamp output ground/shields to the (-) input terminal only as above. This is the one I used (price is $AU):
Pro1327 Stereo Audio Line Preamp with Gain Control 0-15Db | KG Electronic
I'm only concerned about quality because the digitized content will be the final copy and I want to get it right in the first place. Headphone amplifiers do introduce some noise in the way that's why I'm hesitated to use them, What I need is only about 6dB level.
The BE75 digitizes audio at 48KHz/24Bit and in the final encode I down convert it to 16Bit, 24Bit gives some nice headroom for digital boosting but I'd rather get it right at the source and not have to worry about doing that digitally.
The BE75 digitizes audio at 48KHz/24Bit and in the final encode I down convert it to 16Bit, 24Bit gives some nice headroom for digital boosting but I'd rather get it right at the source and not have to worry about doing that digitally.
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I haven't measured the Pro1327 line preamp, but I'm fairly fussy when it comes to audio. I did think I when I got it I might upgrade the op amps and coupling caps inside, but when I opened it up they are pretty good audio wise anyway (or have fake labels!) so I didn't bother. In my system I have only noticed sound improvement from gain optimisation; no degradation from insertion in the signal chain that I can hear. I am using it to listen to broadcast TV and Blu-ray concert recordings from my Loewe Individual TV through my seriously good (IMHO) HiFi system and it is up to the application. I'm sure it's good for your application as well.
LM833 op amp and Jackcon caps. The unit isn't high end audiophile grade, but the circuit isn't rubbish and the application isn't high end either. I wish you hadn't asked this 'cos now I've got the upgrade bug again on something that was working perfectly. 😱
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It's not that bad, 8 electrlytic capacitors, half hour job. DG-key should have HiFi type capacitors, I bought from them before.
If you have any caps in the audio path, best make them polypropylene for ≤ 2.2uF (if they'll fit, of course), and bipolar electrolytics for ≥3.3uF---Nichicon ES are the best.
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I do have a selection of a dozen or so different high end op amps and all the miniature WIMA MK4 film caps 100n up to 2.2µF in three different pin pitches, plus most values of Muse, Fine Gold, Tonerex, Silmic II and Cerafine capacitors in stock as I do a lot of hifi upgrades for clients. When I got the line preamp I inserted into my reference system and decided I couldn't hear any degradation, at least not during a casual listen. YMMV of course!
