Mixing two microphones in front of preamp

[Mailliw]

I am going to be doing sound on a short film using my music recording gear.  I will be using 2 wireless lavalier mics, 1 boom mic and my G9 tube preamp.  I was thinking of mixing the 2 lavalier mics and sending them to one preamp channel and sending the boom mic to the other preamp channel. I have an 8-channel mixer I could use for that purpose, but is there a smaller solution? I'd like to be able to control the lavalier levels when they are mixed.

Is it stupid to mix the two wireless lavalier mics together with some sort of passive resistor+potentiometer box before the preamp?

Thanks.

 

[skipwave]

EDIT: Better advice from folks with experience in this arena follows. Ignore my ramblings.

I imagine the G9 sounds a world better than the preamps in your 8-channel mixer, so it doesn't sound stupid at all.

This will all be simpler if the lav mikes don't mind being connected to unbalanced variable pads, such as 1k ohm potentiometers.

Look at some schemes for passive mixing networks (summing bus) intended for connection to mike preamps for make up gain. Then throw a variable pad in front of each input. You may run into noise issues, this is a very lossy approach.

Alternatively, get a microphone mixing transformer (even 600 ohm line mixing) and throw the variable pads in front of that.

NewYorkDave posted some nice drawing of variable pads using a pot as rheostat to vary the middle leg of a U-pad.

Unless you use constant impedance variable pads (such as so called "Bridged-T"), the output impedance of the mix network will vary and how that affects the G9 must be tested. Generally speaking, the high ratio input transformer should make it less sensitive to impedance variations at its input. Funny thing is an all-tube preamp should be more sensitive to output loading (mitigated to some degree by a step-down transformer).

 

[pasarski]

Hi,

sorry I can't answer your question, but I can say that mixing two lavaliers on one channel is a common thing to do if you don't have enough channels. Also I have to  warn you that using music gear in film shoots can get really messy, not saying it can't work, but in a hurry you may really start to miss dedicated field mixer-recorder combination. In a studio it might be easier, but in a location, ,  I wouldn't even dare to try it.

Anyway, good luck, hope it turns out ok!

 

[Rossi]

I would just use a decent mixer with enough mic inputs. I suppose a Mackie would do. Tube stuff doesn't like to be carted around; you might run into problems there. A working mixer beats a non-working boutique preamp.

Also, lavalier and shotgun mics aren't the most beautiful sounding to begin with. You're not likely to hear an improvement with a nice preamp. EQ might be useful, though.

Keep your G9 at home and use it for voiceover work.

 

[strangeandbouncy]

HI,


  if you are on a mac and OsX, you might consider another interface as a hot solution. If you are running logic or any other core audio sequencer, you can use "Aggregate device" to plum in more firewire devices. I have done this on location(music) to great effect. I was expecting loads of issues, since I was using Duet, Mini-Me, Sapphire, and M-Audio in various combinations. Gotta be batter to have discrete channels for your audio than have to commit levels there and then. I was running 12 different inputs on 4 different interfaces with absolutely no trouble at all.


    Just my pennies-worth, and I ain't NeVeR done any film sound recording, so I may be way off beam, but if it was me. I'd want as much control as possible.


    Kindest regards,


      ANdyP

 

[abbey road d enfer]

I am going to be doing sound on a short film using my music recording gear.  I will be using 2 wireless lavalier mics, 1 boom mic and my G9 tube preamp.  I was thinking of mixing the 2 lavalier mics and sending them to one preamp channel and sending the boom mic to the other preamp channel. I have an 8-channel mixer I could use for that purpose, but is there a smaller solution? I'd like to be able to control the lavalier levels when they are mixed.

Is it stupid to mix the two wireless lavalier mics together with some sort of passive resistor+potentiometer box before the preamp?

Thanks.

You say you have an 8ch mixer. What model? Why don't you use it and forget about the G9? Beware that one of the most critical aspect of film sound is noise. A tube mic pre is not my go-to for this application.

 

[Mailliw]

Thank you for all the suggestions.

This is the mixer I have: http://www.soundcraft.com/products/product.aspx?pid=26

I am sort of leaning towards leaving the G9 at home now... 

 

[abbey road d enfer]

I've done a lot of direct-to-stereo recordings with an E6. I've never had any frustration with it in terms of performance. The mic pres are more than decent.
The only concern is the durability. After some years the accumulation of dust and humidity on the PCB starts creating noise and it is hardly repairable.

 

[mushy]

As someone who does post occasionally... Please don't blend the mics. Record them on separate tracks. And grab 30 sec of room tone in each location.

Keep your rig as simple as possible. Borrow a 4 channel interface with built in pres. The difference between location recording and studio recording is that you will be expected to be very agile and flexible with your rig and yet invisible. The more crap you schlep the harder that becomes. 

Fix it in post is a real thing. The trick is to make it easy to fix with a solid trail of breadcrumbs.