Calibrating a Sound Devices MixPre to a HVX200?

Chadfish

Chadfish

Veteran
Hi

Up until now I have only used my MixPre semi permanently attached to my VX2100 that has the Greg Winter mod. He put a hole in the MixPre casing and I can put it between my camera and tripod, but I have to unscrew a lot of screws....

Anyway I've got a grown-up sound gig with a client who owns an HVX200 camera, and won't be in town until the shoot tomorrow. How do I calibrate his camera to my mixer? My mixer sends out a 0db 1k tone. What needs to be done on the camera?
 
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Send the tone out to the camera and adjust the camera's levels to 0db match the mixer. That way what you see on the mixer is the same as the camera.

Jim
 
Thanks Jim. Intuitively that's what I thought, but I saw some other thread on another forum days ago that was saying something about going +4db on the camera.

Are there any non-defeatable limiters on the HVX200 that may conflict with the MixPre limiters?
 
Jim Carswell said:
Send the tone out to the camera and adjust the camera's levels to 0db match the mixer. That way what you see on the mixer is the same as the camera.

Jim
Click to expand...
Wrong
Set your mixer to 0. Camera should be set to -20.
The 200 has 2 hash marks. The lower (left) is -20. 2nd hash is -12

Sending out the way the first person mentioned, you would be sending out an extremely low level signal at say -10
and having to really gain up at the camera to make up the difference.

There is also a voltage mismatch.
Common reference for tv usage
0 analog = -20 digital
 
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Hi Rippie.

My MixPre mixer doesn't seem to be able to change the tone volume. I just switch on the 1k tone, and the vu meters go to 0db, just before the first red led at +8.

And I don't understand: If I set the camera to -20 rather than 0, won't my signal be lower. You said 0 would be too low.

I admit I'm a noob at this and I'm confused. My VX2100 had no adjustments - with the GW mod it just took whatever the mixer sent and wouldn't clip. With my EX1 I have no trim at line level, so all I can do is change the record levels of each channel.
 
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Yeah, I´m in the same boat as Chad.

Finaly got me a mixer for the HVX200.
The mixer sends out a 0db signal but I have no idea where on the HVX I have to set it.

Frank
 
Rippie's right. If you set the camera level to 0db you'll be using much of HVX pres wich aren't true Line INs, so you're introducing noise.

I usualy set my recorders level to -12. You can set to -20 if you want some more headroom to prevent cliping.

Just send the 1000 cycles to HVX and set it at -20. Ajdust the SD level acordingly thus maximizing the gain on the mixer, not on camera. speak loudly into the Mic and adjust the SD threshold making sure that the HVX doesn't clip.

You then can monitor on the MixPre level LEDS.
 
Chadfish said:
And I don't understand: If I set the camera to -20 rather than 0, won't my signal be lower. You said 0 would be too low.

I admit I'm a noob at this and I'm confused. My VX2100 had no adjustments - with the GW mod it just took whatever the mixer sent and wouldn't clip. With my EX1 I have no trim at line level, so all I can do is change the record levels of each channel.
Click to expand...

0dB in the digital world is 0dB FS, or Full Scale. That means that 0dB is it. The end. The max. There's nothing past it, and hitting or trying to surpass it will result in nast digital clipping.

On your analog mixer, 0dB is the reference point - the ideal spot for signal-to-noise ratio - but there's plenty of headroom above 0dB without bad distortion (and even then, in certain situations - mostly music - some analog distortion can actually sound pleasing).

By setting 0dB analog on the mixer to match -20dB FS on the camera, you are ensuring that you have plenty of headroom as you record. You'll have peaks around -10dB, and that's just fine.
 
Thanks guys.

I'll set the HVX200 to line-in, send the 0db 1k tone from the mixer to the camera, turn down the camera levels until the tone signal hits -20 on the camera's meter, and I should be good.

Right?
 
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Chadfish said:
Thanks guys.

I'll set the HVX200 to line-in, send the 0db 1k tone from the mixer to the camera, turn down the camera levels until the tone signal hits -20 on the camera's meter, and I should be good.

Right?
Click to expand...

well as you know thats just the basics but yes thats the proper setting.
When you mix on the mixer don't hover at 0db.
That would translate to -20 on the camera which would be too low of a signal.

Instead be hitting +8 +10..etc on the output of the mixer which
will then translate to a -12 -10..etc

Ive never used the mix pre but I know the metering on it is very limited above 0 which sucks, but this is the way you do it.


If this was the old days of beta SP (analog cameras) yes you would put 0 on the mixer and 0 on the camera and then it would be a what you see is what you get. Of course back then you wanted to peak really not much higher than +6ish.

Different beasts.

On the 200 camera you'll see the 2 hash marks you want your signal to be peaking slightly above the -12 mark (1 or 2 bars)
That will put you in the pocket of correct levels.
 
To clarify a bit: 0dB on analog systems refers to a certain voltage, usually referenced as 0dBVU. The 0dBFS is used in digital systems, where 0 dBFullScale means all bits are used up in a sample and the signal can not get louder (and will clip/distort badly if you try).

0dBVU = -20dBFS IMPORTANT!!!!!!!!!!!!!!!

This is where things get confusing: in analog the zero level 0dBVU is NOT the maximum level, but all systems can go to +12, +20 or even +24 dBVU.

The idea behind calibrating an analog mixer to a digital camera is to align the 0dBVU test signal from mixer to -20dBFS level on camera. After this is done, it is impossible to clip the camera if the levels are kept below +20 dBVU on the mixer.
 
also chad, having an ENG/breakaway cable is really good so you can listen from the camera's headphone jack and can hear whats being recorded there.
 
Chadfish said:
Hi Rippie.

My MixPre mixer doesn't seem to be able to change the tone volume. I just switch on the 1k tone, and the vu meters go to 0db, just before the first red led at +8.

And I don't understand: If I set the camera to -20 rather than 0, won't my signal be lower. You said 0 would be too low.

I admit I'm a noob at this and I'm confused. My VX2100 had no adjustments - with the GW mod it just took whatever the mixer sent and wouldn't clip. With my EX1 I have no trim at line level, so all I can do is change the record levels of each channel.
Click to expand...

Tone is fixed to send 0VU, that why it can be used for calibration - it's sending a known, fixed level that doesn't change with settings of the input channel faders or the output master level fader (not that the MixPRe HAS a master output level control, but other mixer's do). With tone, average and peak levels are the same. But with voice, peak levels are usually about 8dB higher than average. If you send tone from the mxer at 0VU and adjust then camera's input levels so its meters are reading -20dBFS, when you are sending speech that the mixer's meters also shows as 0VU, the camera's peak reading meters will show levels bouncing around -12. But speech isn't a constant level monotone, there are times when it gets louder. So while calibrating tone to -20 in the camera means your normal speech peak levels will generally be around -12, it ALSO means you have an additional 12dB of 'headroom' before you hit the clipping danger zone up near 0dBFS.
 
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One thing to watch on the mixpre is that the tone level will creep on you as it warms up. Best to have it on for a minute or two before you calibrate.
 
manglerBMX said:
also chad, having an ENG/breakaway cable is really good so you can listen from the camera's headphone jack and can hear whats being recorded there.
Click to expand...

Yes Mangler I have ordered one of those. I already have 3 cables going to the camera (2 XLR and 1 mini to hear the camera) which is cumbersome. I should have ordered one earlier, but I'm usually running the camera and doing the sound. I got a great deal with a custom made one: 25' for 200.00, and it includes a female mini jack at the camera end so the camera operator can monitor too. They even print my name on the cable. They use Mogami cables. You can get extensions for: 15' - 75.00, 25' - 90.00, 50' - 125.00, 75' - 160.00.

If anyone is interested it's a guy named Blake Wilcox - fredfstone60@hotmail.com
His site is being changed over but here it is in it's incomplete form: http://www.wilcoxsound.com/
 
gco said:
One thing to watch on the mixpre is that the tone level will creep on you as it warms up. Best to have it on for a minute or two before you calibrate.
Click to expand...


Ya know, I thought I saw my tone at +4 on the mixer after a while, but then on 3rd look it was back to 0db. I think I just read it wrong.

Thanks for the info guys. I'm off to my gig. 3 one hour interviews. I only charged 250.00.

What would you charge for a simple one camera interview gig?
 
Chadfish said:
What would you charge for a simple one camera interview gig?
Click to expand...

The same as I would charge for a complex day. (as long as the gear was the same)
A day rate is a day rate.
It doesnt matter what you do.

2 days ago I did a job where they had to just get a few b-roll shots
for an on going project. No dialog.
I think the best sound I got in the 6 hours "they" worked was a car door closing.

Yesterday did a job in a warehouse where I proceeded to hang out in a comfy chair near the front while the other guys shot b-roll for 80% of the day.

Point being is along with the hard days you're going to get easier days.
Its always the same rate. Your time is your time.
 
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