If I buy a mixer with a preamp, can I plug it into my camera without the two amps killing each other?

Question

I'm going to be connecting a microphone to a camcorder, I'll be using a 3.5mm connection (yes I know it sucks, I'm planning to upgrade to a camera with XLR inputs later, but for now...) my camera has a built in automatic preamp, but I'd like to have a little bit more manual control over the levels.

If the answer is yes, can you recommend any portable, battery powered mixers, that can connect to my camera, have a VU meter and headphones out?

I believe I can use this mixer http://www.maplin.co.uk/module.aspx?ModuleNo=31137&doy=12m7. It has no headphone socket, but I can plug the headphones into my camera. What I'm really worried about is, it has no VU meter, only a clip light. Is it possible to somehow attach a VU meter by plugging it between the output socket and the cable going to the camera?

Answer 1

You would need to be careful where you take your audio output from on the mixer, if it is a monitor level output then yes, you will fry anything except powerful pa monitors.

Fortunately most powered mixers use the unique 'speak-on' connection to avoid such a scenario, however some cheaper or older powered mixers may still use unbalanced jack outputs.

(the modern convention is to use seperate connection types for different level voltages, monitor level is usually 'speak-on' line level is usually jack & mic level is usually XLR, this is a failsafe way of avoiding damage to delicate equipment, but don't take it for granted)

The safest ways to do it would be to take a line out from the XLR, headphone or phono sockets, these are usually all at 4v line level or thereabouts.

You can buy in line attenuators to reduce the level to mic level so as not to overload the mic level input on the camera, but as an earlier poster rightly said: "whats the point?"  the camera is likely to do it's own thing anyway.

There are a few exceptions to this:

The Sony VX1000, VX9000,  VX2000, VX2100, TRV890, TRV900, TRV950, HC1000, HC1

Canon XL1, XL1s, XL2, XM1. XM2, XHA1

Panasonic DX100, DX110, MX300, MX350, MX400, MX500

EZ30 EZ35

If you have any of the above then you can control the audio level on the mic input.

The best way to control the audio level is actually via a beechtek, I use a DXA-4, these have mic level /line level switching, mono/stereo mix, L & R independent audio level pan, mini jack and XLR input.

If you don't have one of the models I mentioned (WHY DIDN'T YOU TELL US THE MODEL OF CAMCORDER?!!!!!)   then if it were me I would record the audio seperately onto minidisc or a digital recorder at the mixer.  This frees up the camera with no cables limiting movement or having people trip over.

Remember to record at 48khz where given the option and creating a synch point.

Conventional VU meters aren't great for DV recording, where the optimum record level is -18db with a -12db peak, if your camcorder has an audio level control then you should be able to show the meters on the LCD, older models such as the VX1000 and the EZ30/35 had a peak warning only.

Other problems you will encounter is that a good audio engineer is doing an EQ mix for the accoustics of the room, usually this sounds duff on a tape, very flat, unless they have an ambience mic facing out to the crowd.

In your situation the onboard camera sound may be more rounded so when you edit you may want to mix in a little of the onboard mic to flesh things out.

If you want a portable mixer that has its own power, input options a plenty, and vu meters, then the last word is SQN.

Expensive, but they come up used and a good un will last forever.

PS. As a response to the first poster, the most popular reason to have an external mixer is actually to have a dedicated sound person controlling the audio levels before they reach the camera, this avoids camera shake from on the fly adjustment at the camera (a safe level with headroom is set from the test signal on the mixer) and is one less thing for the camera person to be worrying about.

Any professional format camera has three audio settings at the XLR connection, LINE Mic Mic48v.

Answer 2

i would pass on getting a mixer until you get a camcorder that offers manual level controls and line level input. the VU meter on the mixer won't mean much if the camcorder has automatic gain adjust.

the usual reasons for an external mixer on a camcorder are

1. the camera does not have mic input, but does have line inputs

2. you need to use phantom power for the mic

3. you need to convert xlr mic(s) to unbalanced input.

if you drop the requirement for VU meters and phantom power, you don't need a powered mixer, which mean one less thing to provide batteries for. if the mixer you get only offers line level out, you can put a 40 or 50 dB attenuator on the output to get it back to mic level.

Answer 3

Agree with lare... but to answer your question directly, when you plug the XLR adapter into the 1/8" (3.5mm) audio in, that bypasses the internal camcorder pre-amp.

juicedLink and BeachTek have XLR adapters with active pre-amps and LED VU meters so the "one more piece" (standalone VU meter) issue goes away.