Help me understand impedance

[Ty Ford]

Originally Posted by Samuel Birkan

I recently bought a Rode VideoMic for my TRV950. I found that I have to take the "volume " control down to -20Db and that Auto Gain is impossible to use (I know I should not be using it but I was in situations where I could not put on a headset).
The Rode Specs say - Output Impedance 200 Ohm, Then "MIcrophone will operate satisfactorily int a load impedance as low as 1k Ohm.

The TRV950 specs say "Mic Jack" low impedance,,, output impedance 6.8k Ohms.

The Sony Ecmms908 Mic says Output Impedance 1k Ohm. (This Mic works fine on Auto Gain)

Can someone comment on the compatibility of these devices and maybe explain why 1k Ohm is "lower" than 200 Ohm

Thanks
Sam

Hi Sam,

An interesting thread here.

Don't confuse output and input impedance. If the TRV950 specs say ' "Mic Jack" low impedance,,, output impedance 6.8k Ohm', that's very misleading. Inputs don't have an OUTPUT impedance, they only have an INPUT or load impedance.

Further, impedance and mic sensitivity are separate issues. Just because a mic has a higher impedance doesn't mean it will be more sensitive.

More to the point, the VideoMic is more sensitive than the other mic. Unless you can back down the input at the camera (controls which exist on all pro cameras and many consumer cameras), your options are to use inline pads or (well not in this case, but otherwise) use a mixer between the mic and camera that allows you to control the level more finely.

You are moving from a one person band to a use which really requires more than one person paying attention to things. How do I know this? Because you say you are using Auto Gain.

A good sound person does more than sit on a stool and watch the meters. Among a LONG list of audio related things, a good sound person is constantly making minor adjustments to make sure the sound is as good as it can be; even if the shot is just talking heads.

I'm not suggesting you hire a sound person. I'm just pointing out that as the complexity and quality of your work becomes more demanding, there's just too much for one person to pay attention to. Something will suffer.

Welcome to the world of professional audio/video. :)

Regards,

Ty Ford

PS: I'm giving another Audio Bootcamp Seminar next week end here in Baltimore a my studio. We'll spend 4 hours going over nothing but audio; which mics, where, when, mixers, levels, camera inputs and, as amazing as it seems, four hours goes by in a flash.

[Steve House]

Originally Posted by Ty Ford

Hi Sam,

An interesting thread here....

Ty Ford

PS: I'm giving another Audio Bootcamp Seminar next week end here in Baltimore a my studio. We'll spend 4 hours going over nothing but audio; which mics, where, when, mixers, levels, camera inputs and, as amazing as it seems, four hours goes by in a flash.

Do you ever make up Toronto way for your seminar or into upstate New York? Would love to attend some day but BWI is just a bit too far.

Saw your stint as a taxi driver last night. Ain't it a dirty shame! <grin>

Steve House

[Ty Ford]

Originally Posted by Steve House

Do you ever make up Toronto way for your seminar or into upstate New York? Would love to attend some day but BWI is just a bit too far.

Saw your stint as a taxi driver last night. Ain't it a dirty shame! <grin>

Steve House

Steve, I quite understand. I haven't taken it on the road yet other than down to DC several times. I'm trying to keep costs down. The event here only costs $75, includes the Bootcamp Book and is limited to six people so I can give each person some direct help with his or her rig. Some say that's a ridiculously low price.

I can't afford to fly anywhere running that sort of deal. If I came to Toronto (lovely city, BTW) I'd probably want to do two sessions; a Sat. and Sun. to make it worth my while.

Airfare, hotel and a space to do it in would all have to be added up and I'd have to make a bit to keep the house, studio and groceries back home.

I've done seminars with 30-40 people. Not quite the same as doing it with six, but everyone seemed to get a lot from it. Find me a video users group and lets see if we can figure out how to make it work! ....um, before Winter sets in, please. :)

Regards,

Ty Ford

[Greg Boston]

Originally Posted by Ty Ford

Find me a video users group and lets see if we can figure out how to make it work! ....um, before Winter sets in, please. :)

Regards,

Ty Ford

Hey Ty,

That's when you bring the tour down here to Dallas and the southwest like Phoenix. You get to stay nice and comfy warm while everyone is freezing in Baltimore. (Hehe).

Actually, I was going to ask the same question that Steve did about taking the seminar on the road. Final Cut Pro user groups are pretty strong around the bigger cities and would probably love some help tweaking audio both hardware wise, and software wise (Soundtrack Pro).

You may have an untapped revenue potential if you can handle the travel.

regards,

=gb=

[Ty Ford]

Hey Greg,

Dallas is very doable. I haven't had the need to do Soundtrack Pro yet because I use Pro Tools LE and a Digi 002 Rack for most of my stuff. I have been doing some work in the old Soundtrack and in Garage Band.

I just created a bunch of beds for a Mockumentary as part of a 48 hour film festival up here. Garage band has some nice sounding software instruments. The piano is great. I'm using it on a singer/songwriter project for a client. You can hear what that sounds like by clicking on Debbie Bilezikian's track "Threads" here: http://home.comcast.net/%7Etyreeford/Library.html

SW Airlines might actually make it possible for me to do Dallas. Don't know about Toronto. I'll check.

Regards,

Ty
410.296.2868

[Greg Boston]

Originally Posted by Ty Ford

Hey Greg,

Dallas is very doable. I haven't had the need to do Soundtrack Pro yet because I use Pro Tools LE and a Digi 002 Rack for most of my stuff. I have been doing some work in the old Soundtrack and in Garage Band.

I just created a bunch of beds for a Mockumentary as part of a 48 hour film festival up here. Garage band has some nice sounding software instruments. The piano is great. I'm using it on a singer/songwriter project for a client. You can hear what that sounds like by clicking on Debbie Bilezikian's track "Threads" here: http://home.comcast.net/%7Etyreeford/Library.html

SW Airlines might actually make it possible for me to do Dallas. Don't know about Toronto. I'll check.

Regards,

Ty
410.296.2868

I use and love Garage Band. I am also a musician and it compares nicely to my flagship Yamaha ES7 workstation synth. I'm also able to use softsynths with it such as Arturia's beautiful re-creation of the Arp 2600 and Yamaha's CS-80(a great synth but it's a 200lb behemoth). Will give the soundbeds a listen.

-gb-