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Old June 6th, 2008, 05:34 PM   #1
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FP 33 and XL2

I got a Shure FP33, and have been advised that simply going into the RCA inputs on the XL2 to get a line level signal might not work because the Shure's line output is to hot for the XL2's line inputs. If I want to still give them cam a better-than-mic level signal, what are my options?

I've also been advised going from the tape outs might work, or some kind of external pad.

I also have the Beachtek XLR adapter (DXA4C) that I kept when I sold my XL1s, which also plugs into the RCAs. I tried the mixer this way earlier, and it sounded fine, but I wonder if I had something set wrong. I always assumed (wrongly?) that the line switches on the Beachtek attenuated its inputs, since when I tried messing with it before when I had mics plugged into it, my signal would disappear when I flipped from mic to line. So setting those to line AND going into the the RCAs would be doubly attenuating the incoming signal, or something. I had the inputs on the Beachtek set to mic when I did my test. Couldn't go straight into the RCAs from the mixer because I don't have the correct adapters yet. I wanted to post here before I bought more cables.
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Old June 6th, 2008, 09:15 PM   #2
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Hi Josh,

The FP 33 has mic level outputs. Use them. Use the XL2 balanced XLRs and run at mic level. No worries. That's what I do with my XL2 and Sound Devices 442.

Regards,

Ty Ford
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Old June 6th, 2008, 09:24 PM   #3
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Aren't there serious benefits to recording line level? More head room, better s/n ratio? Do you like the Mic ins better 'cause they're balanced? I've heard that if you have a really short cable run between mixer and cam (less than 10 ft), this isn't usually an issue.

P.S. found a cable, and tried using the tape out from the FP 33 to the RCAs. It works, but in order to get the 1Khz tone to match -12dB on the XL2, I had to crank the XL2's pots almost all the way up. At a certain point, even as I continue turning them, the cam stops giving me more volume. So it seems the tape outs are a bit weak.
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Old June 6th, 2008, 10:24 PM   #4
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Josh,

Serious is a big word. I'm first an audio guy and then a video guy. I have had no problems with mic levels to my XL2. Balanced audio (with XLRs) is very useful.

Headroom is relative to the individual circuit, regardless of whether it's mic or line level. The same for S/N figures.

Many "line level inputs" are simply mic level inputs with a pad in front these days, instead of bypassing the mic preamp.

Incidentally, check the headroom on your FP33. Shure uses dBV (Outputs 31 dBV ) to measure the mic level out and the FP33 has more headroom than the +4 on the meter.

I'm thinking you should be able to set tone lower than -12 on your camera. I set mine at -20, but my 442 mixer has at least 20 dB of headroom. I set tone from the 442 mixer to -20 on the XL2. The 442 meters go up to +20. I set the 443 limiter threshold to about +16. That gives me 4 dB of safety and that's even a little more because the limiter catches peaks over +16.

The FP33 may have as much at the mic level as it does at the line level and that's +18 dB. So if you set your tone at -18dB, you'd run out of mixer headroom just as you ran out of camera headroom. Experiment and let us know what you find.

Regards,

Ty Ford
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Old June 6th, 2008, 10:37 PM   #5
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Thanks.

I always though higher-end cams were meant to average/have tone at -20, but cams like the XL2, DVX, PD150, etc. have crappier electronics than those cams, and hence a lower s/n ratio at any given volume level, so I though -12 was the target on these types of cams. There's even a highlight on the -12 on the XL2's meters, and I remember the XL1s had the same thing.

I'll have to investigate more deeply the other stuff you mentioned, because I'm not much familiar with the math side of audio. My knowledge goes about as far as "line level better than mic level" (or so I thought).
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Old June 7th, 2008, 05:40 AM   #6
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Josh,

Crappier is a good word; indicating the high end cams are also crappy, just not as much. :)

Some of this is a math game, but were I to set tone at -12, I'd have to be VERY careful of the level.

I'm not sure where the -12 thing got started. I do know how much swing an audio signal has and that if you can keep peaks at -3 to -6dB on your camera, you're getting the best audio you can get.

The older Shure mixers with their analog meters don't show continuous peaks. The newer mixers that Sound Devices make show both peaks and RMS (VU) at the same time. Peak is what you want to keep an eye on.

Regards,

Ty Ford
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Old June 7th, 2008, 05:49 AM   #7
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I don't know where the 12 thing came from either (as I said, I'd always heard it was because of the electronics in the prosumer cams, and their higher s/n ratio at any given volume, a situation where a -20 target might give you too much noise when the sound is softer), but I've been aiming to keep sound between around -20 at the LOWEST, to -12 average, letting it go into the -6 range for louder stuff, and if it goes higher, oh well, long as it doesn't clip!

when I (very occasionally) edit, I output with the same goals. . .-20 is about the lowest, -12 for loud but still normal speech, and shouting or the like can go to -6 or so.

You think if I let it average way down there at -20 on the XL2, it'll be okay in post?
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Old June 7th, 2008, 07:47 AM   #8
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That's not what I said. I said set tone at -20; not record with average levels at -20. Your peaks on the camera should be hitting -3 to -6 dB.

With 0 dB tone from my 442 mixer, I set the camera meters to -20. My mixer meters go up to +20. The 442 mixer meter goes from -30dB to +20dB. That means I have a usable dynamic range of -30 dB to +20 dB. On a quiet set with no one talking, my 442 meters are down around -30dB. An FP33 doesn't read down that far, so you haven't noticed. -30 to + 20 means a usable dynamic range of 50 dB. Obviously, you want to keep the level higher for any audio to keep it out of the camera noise floor.

I set the mixer limiter to catch any peak over + 16 dB. Some of the fast peaks will get though, but I still have 4 dB (the space between + 16 and + 20) before the camera clips.

I adjust the input trims and mixer knobs so my PEAKS are at +14 to +18 on the mixer. The VU (RMS) level is below that. How much below depends on the sound source. Among people's voices, the PEAK to RMS ratio varies significantly. With some folks the difference between PEAK and RMS is 4-5 dB. With others it can 8-9 dB. This is not while they are shouting and then talking quietly. It's while they are talking at a steady level. I'm sometimes amazed that we are all part of the same species.

Again, because the FP33 doesn't really show PEAK very well, you are unable to see what's going on. That's one of the many significant advantages of all Sound Devices mixers. Were I you, I'd start planning for a Sound Device 302 mixer. Your ears will thank me. :)

Regards,

Ty Ford
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Old June 7th, 2008, 08:07 AM   #9
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And let me add a note.

Last month we were using a new digtial video camera with XLR inputs. This camera had NO NUMBERS on the metering. I set tone at -20 to one of the dots and did my usual talk checks while listening to the camera return of the headphone output. (It's VERY important to listen to the camera and not just the mixer.)

The camera (which we hadn't worked with before) was clipping when I was running normal levels. Mixer output and camera input switch were set properly -- mic to mic or line to line, I forget which. Something weird was going on. Maybe we chose the wrong dot. WHO COULD KNOW!? The owners manual was not available.

The 442 outputs can be switched from mic to -10 (consumer line) to +4 (pro line). I switched from line level to -10 and resent tone, calibrating using the same dot. (I probably could have chosen a lower level dot as well and not switched to -10.) Bottom line; we got good level to the camera and I heard no clips in the camera headphone.

We further insured ourselves by recording a bit, playing back and listening. Levels were good. No distortion. Off we went while continuing to listen to the camera output. No problems.

Hope this helps.

Regards,

Ty Ford

Last edited by Ty Ford; June 7th, 2008 at 08:18 AM. Reason: typo
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Old June 7th, 2008, 01:38 PM   #10
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The -12 thing is a bit odd really as the dodgy cameras such as PD150/70 etc are accctually very unforgiving of high levels and seem to break up (distort) before they should. Therefore they need the same headroom as anything else.

The idea of peaking at 8db above tone is that it reflects the fact that the old world analogue PPM meters were, although considered fast at 10 ms response time, actually letting through up to around 4 db and more when pushed. Therefore the dbfs digital world needed extra headroom.

I've tried running the levels hot and laying tone at -12 but it gets you in trouble as it leaves only 4db for compressor/limiter overshoots which is not enough. As stated above, 4 db is normal for the margin which the PPM fails to register. This assumes that one's PPM is set to the BBC standard of 10 ms response time. Personally I keep this even in software emulations of the PPM as it looks right. Once you are conditioned to these meters they have a certain feel to the rise and fall of the needles.

In conclusion - you are best to avoid the -12 thing. If levels are run proprly on a mixer to peak in the right sort of area then lay tone at -20 (-18 for us English) and peak 8db above as measured on the PPM. (Higher by 4 db or more in reality.)

Without wanting to stir it up or anything I personally find my SQN works well with the rca line ins on the XL2 XL1's which I have used but of course all set ups are different. That's sound gear for you. One day I'll have some issue maybe running unbalanced and then I'll eat my hat. (incidently I tend to run a 5 Meter coilly cable and sometimes a 10 Meter straight attached on to it so I guess I'm inviting trouble. Sounded better on my tests though.

Cheers.
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Old June 7th, 2008, 03:10 PM   #11
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Sorry, I misunderstood the tone thing, then. I always thought (apparently wrongly) that where you put the tone was where your average was supposed to be so, on a broadcast cam, you set tone at -20, and average at the same. I will correctly my thinking.


So, I can set tone at -20, still have stuff hitting -12 and -6, and everything's groovy?

The XL2 and XL1s have always behaved as it seems they should, for me, not distorting 'til 0.

Thanks.
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Old June 7th, 2008, 05:33 PM   #12
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I've found the XL2/1 to be better for sound than most.
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Old June 8th, 2008, 03:50 AM   #13
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Ok, I tried the -20/-18 thing, going from mic out of the mixer to the mic ins on the XL2, set tone at -20. I yelled into a ME66 from right next to it. Even when the mixer's pegging, and I can hear the distortion when monitoring out of the camera, the camera's meters still only show around -6, even as I yell louder and louder. What does that tell us?

I guess I always thought the point of tone was to sync the camera and the mixer in such a way that 0 on a mixer = a certain level in the camera (-20, -12, whatever), so that as you watch the mixer's meters, you know what the cam's getting.
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Old June 8th, 2008, 11:53 AM   #14
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-12 comes from post. quite honestly when mixing to -12 = 0db analog betaSP tape machines like that level. it means you've got about +3 to +6db of headroom from there. 1800's only show +3, but they can handle hotter.

so that said, I have a FP 33 and I run it at 28V. I've got 2 batteries in series of 10cells (using a custom hand built power system to also supply 12Vwith common ground for wireless) and when they come off charge, they are 28.5 V and drain down to around 22V when done. the mixer is totally different at these levels ! it has much more head room, and sounds MUCH MUCH cleaner. its almost clip free at that range. even a pair of 9V's drain down to about 14.5ish when near dead. if you are using an external 12-14.4V system, you'll have clipping in the mixer as you turn any of the channel levels up past 7 because at those voltages, the mixer is barely functional, and why I think people tend to dismiss it as not being as good as a SD mixer. you just have to juice it up.

so that said, my HD100 camera boosts mic level to line level, and those premaps are NOISY ! so I always run line level to the camera and then I get good results. it likes having a hot signal. other cameras as Ty said basically pad line down to mic, then pre amp to whatever the camera uses internally :(

a pair of 10db pads can be helpfull when you have clipping even though the switches are right, but the camera can't take a real line level. you really do need to play with some cameras sometimes and test.... and always listen to the camera return.
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Old June 8th, 2008, 01:09 PM   #15
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You're saying that with the mixer plugged into a wall socket, rather than running of batteries, it won't perform as well?

Also regarding the return, I don't really get how it works. . .the manual isn't terribly clear on it. It's the "mon in" switch right? But how do you set the whole thing up?
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