Mic and Line feed?

Chienworks wrote on 5/25/2005, 7:25 AM

Basically correct. Mic level is in the neighborhood of 0.001 volts and needs an enormous amount of amplification to be useful. Line level is around 1 volt and is pretty constant between most audio devices such as tape decks, cd players, mixers, fm tuners, etc. A mic preamp raises the microphone level to line level so that it can then be used by other audio equipment.

John_Cline wrote on 5/25/2005, 7:44 AM

Yes, that's one way of looking at it. Mic level is on the order of millivolts, perhaps 5 to 50 millivolts depending on the sensitivity of the microphone and how loud the source is. Line level is considerably higher in voltage, -10dbv audio is 316 millivolts and +4dbm "pro" line level is 2.2 volts.

John

Grazie wrote on 5/25/2005, 8:35 AM

Kelly & John thankyou . . follow-ups . . didn't think I was gonna let yah off the hook so easily . . LOL! But this is my logic issue . . .

Sooooo.... I have a battery powered K6-66 Senni mic. What is coming out of the XLR connections from this mic? Tiny mic voltage OR pre-amp? Anyways, for me, this then goes into into my Canon XLR adaptor ( Canon MA300) - after which it is called what voltage? Then it appears - I guess - at the taspe head and is "splashed" on the tape.

Sooooo... I can feed into the Canon XLR what type of feed? Obviously I have success with stuff coming from my Senni . . . what OTHER feed can/could I feed into it? If I wanted to take a line feed from a sound desk, I'd just plug this in to one of the XLRs? I'm presuming I'm getting a LINE ie amplified feed.

Sooooo.... One XLR is taking a feed from a Mic feed and one is taking a feed from a Line feed? See my quandry?

Apologies if this is a real dumbo question . .

TIA,

Grazie

Chienworks wrote on 5/25/2005, 8:44 AM

The battery power for that microphone is running the electret element. The output is still mic level, not line level.

The MA300 appears to only accept mic level inputs. If you want to feed it a line level signal you'll need an attenuator of some sort. IF (big if) you can control the output level of whatever else you want to plug in, you might be able to turn it down low enough to get it to the point where the camera's gain control can handle it without distortion. However, you'll probably get some noise this way, both from the mismatched signal level and also from mismatched impedence.

Most XLR mic inputs are around 600 ohms impedence or less. Most line level signals are 5000 ohms or higher and expect at least that much impedence from the device you connect them to. If you plug a high impedence source into a low impedence input you can get some nasty buzzing. Then again, you may not. A proper attenuator should also take care of the impedence mismatch for you.

rs170a wrote on 5/25/2005, 8:56 AM

Repeat after me Grazie.
There is NO such thing as a dumb question!!!
Done? Good.

The signal coming from your Senni is still at mic (very low) level. From what I could Goole about your MA300, it's an adapter to get dual channel mic. level XLR inputs into your camera. That's it, that's all. It's not designed to take line level inputs from a sound desk. To do that, you'd have to invest in a Line Input Adapter to knock the signal level down. Sorry :-(

Mike

rs170a wrote on 5/25/2005, 9:26 AM

Looks like I need to get my typing speed up so that I can get my responses in faster :-)

A couple more thoughts on this for you Grazie.
Some sound desks (we call them mixers on this side of the pond) have mic level outputs that you might be able to tap into.
An alternative is for you to invest in a cheap mixer like the Behringer Eurorack UB502" (31 GBP list incl. 17.5% VAT) or the Eurorack MX602A (no price but it shouldn't be much more).
Several folks I know around my area have been using Behringers for years and, while the quality & features aren't quite up to something like a Mackie, the price is certainly a lot less. HTH.

Mike

Grazie wrote on 5/25/2005, 9:31 AM

Kelly + Mike! THANK you! Wooohoo .. now I get it thoroughly . .

OK - Right - on the Canon XM2 I do have an option for Mic Attenuation [ another reason WHY I bought this well priced camera ] - I've used it, it works very well on "hot" sounds. PLUS recently I bought myself an inline XLR 10dB 200 ohm fixed attenuator. So what with the Canon Mic Attn - this hits both channels of XLR, don't think I can ATTn just one or the other - AND using the 200ohm-ie [ as in Home-y ] I should be well covered?

But you guys have truly "killed" some issues I've been sitting on for sometime now.

Mike, thanks for the understanding too!

Love the peeps on this Forum - too good . . too good!

Grazie

rs170a wrote on 5/25/2005, 9:47 AM

A 10db attenuator won't do you a whole lot of good Grazie.
Mic output for something like your Senni is typically rated at around -50db. Line output is anywhere from -10 to + 4. This is where you'd really need something like the Shure adapter I mentioned earlier. I've got a couple and they've saved my hide more than once.
BTW, in addition to books from someone like Jay Rose, an excellent web resource is Equipment Emporium.
Happy reading.

Mike

Seth Bloombaum wrote on 5/25/2005, 10:27 AM

To clarify, to knock line level at +4 down to mic level you need an attenuator of 50db. Anything of 30db or more will get you into the right range. Audio-Technica makes an inline xlr att. that is switchable, which is very handy.

Graz, you can also add your 10db in line if needed.

Catwell wrote on 5/25/2005, 12:05 PM

I use the same setup you have (exceot we call it a GL2 over here). I use a Mackie 1202 mixer which has a mic level output. I still have to activate the attenuator in the camera. I can't drop the level at the mixer because I also feed the line level out from the mixer to my hard disk recorder which has no level control, and needs to see +4dBu. The results with the GL2 are very good, not as good as as the hard disk but quite acceptable. I always run with manual level control and preset the levels to make sure that anything I send from the mixer will not clip the camera signal.

JohnnyRoy wrote on 5/25/2005, 3:16 PM

Grazie,

Another (much simpler) options is to get rid of the Canon MA300 and get a BeachTek DXA-4P Dual XLR Adapter. This will eliminate any external pads, adapters, etc. The XLR inputs are independently mic/line switchable. It also has a separate input for a wireless mic. (I have a DXA-2S that I use)

~jr

Grazie wrote on 5/25/2005, 8:53 PM

Yeah, it was only time before a friend here was gonna say - Get Rid! - Yup, I've known about the Beach-Tek range for about 3 years. I'been humming and hawing over the Dx6 and now the 8, which TorS owns. . .and yes this would "kick-out" the need for a mini sound desk.

JR, of course you speak sense. I should have had you with me when I bought the MA300 in Nov '02. Guess I've had me monies worth outta it - it DON'T owe me a living now. Maybe a sale and upgrade. Hmmmm ... ?

Grazie

Coursedesign wrote on 5/25/2005, 9:43 PM

Anyone else ever break the stamped spades on Canon's XLR jacks on the MA-200/300? I was on location in the Arizona desert for a crucial shoot with oodles of people, finally solved the problem with a very small screwdriver.

They should have used Cannon XLRs instead, those use cast spades for release!

(NB: Cannon makes connectors, Canon makes good cameras and crappy connectors.)

Canon is named after Kwannon, the Goddess of Wisdom.

No kidding.

They should have listened to her before choosing those connectors...

Grazie wrote on 5/25/2005, 10:03 PM

LOL! . . .G

farss wrote on 5/25/2005, 10:11 PM

There's XLR connectors and there's XLR connectors. I've had ones that will not latch, I've had one where the plug will not go into the socket withour a hammer and I've had ones that just fall out.

Although not a 100% reliable guide price does seem to have a bearing on quality.

Back to the topic though, I guess I'm putting on a Red hat here seeing as though he's not around. I've repaired a few Beachtek boxes and well as good as they are the transformers in them aren't all that flash, no uMetal shields so they could pick up stray hum fields etc and I wonder how well they cope with +4dB pro line level. I think Jensen make a way better unit but it'll cost big time.
The other thing is taking a feed from a desk through these units and back into a mic input isn't the best for sound quality. The desk's mic pres have added their own amount of noise as they added 50dB gain, then you're attentuating it back down -50dB only to feed it through another mic preamp and given that it's one in a camera it's not going to be all that flash a preamp.
The ideal solution is a standalone recorder sitting near the desk, this will not only give better sound it avoids the hassle of having the camera tethered to the desk and running long leads. I've been in venues where that was a major issue, having to tape down 100 yards of mic lead is no fun and then having to rip it up again after the show.
The other major drag with any of the Beachtek etc units is if you've got one of those cameras that loads from the bottom, changing a tape can be quite a challenge.

Bob.