Topic: Sound Devices MP-2 :: Proper gain settings for recording...db wise...

[hexyjones]

My friend has an MP-2...just where should he be setting the levels...db-wise...? and is dbu different from db?

I somehow thought 0db would be the ideal setting...but he always runs them all the way to +12 and up...

And what do the little lights above the knob mean...? clips?

And how much gain should he send to his SBM1?

[Chris K]

i usually start my mp2 dials at about 9 o'clock, and adjust to taste when the band comes on. more often than not i am decreasing to the 7 or 8 oclock range, then dial in while watching the meters so that the levels are even.

with that said i run the sbm-1 as close to 10 as i can, i usually end up somewhere between 7 and 9. i like to run the sbm-1 hot with periodical over lights. as long as the over lights are short in duration you are ok...its when they are on for a second or two that you will hear it on the tape

[hexyjones]

Thanks - I'm looking for more specific info...perhaps not even specific to this device...

Does anyone know the proper way to gain out a channel for recording???

"Adjust to taste..." doesn't really seem like the final word...

[nic]

its really going to depend on the rest of the signal chain, ie, the hottness of the signal from your mics and the AD you are using.
there is no set-in-stone value to always use.

the lights above the gain knobs are clipping indicators. I run mine just "under" the clipping level then adjust from there with my AD...ymmv

[MattD]

since the mp2 is an analog device, 0 dB is not the 0 dBFS that you're thinking of where clipping occurs in the digital domain.

[nickgregory]

I run the mp2 with the knobs all the way to the left...if I turned them anymore that direction I would break them off.  Paired with the MGs which are a hot mic, I can still only get the Mod SBM to around 4 on the dial and I am bumping 0...

[F.O.Bean]

I run the mp2 with the knobs all the way to the left...if I turned them anymore that direction I would break them off.  Paired with the MGs which are a hot mic, I can still only get the Mod SBM to around 4 on the dial and I am bumping 0...

so nick, isnt that 'no gain' on the mp-2

why even use it

not being rude, im just curious

[nickgregory]

I run the mp2 with the knobs all the way to the left...if I turned them anymore that direction I would break them off.  Paired with the MGs which are a hot mic, I can still only get the Mod SBM to around 4 on the dial and I am bumping 0...

so nick, isnt that 'no gain' on the mp-2

why even use it

not being rude, im just curious

actually it is +6 db of gain, even at 0 on the knobs, since I am running out of the XLRs.  But your right, the key reason to have it is Phantom Power, and in the cases where I need to boost one of the channels if I am off center to balance it out.

That being said, one of the things I am considering doing is getting a PS-2 and modding it to RCA outs, and trying that for a stint, but that is a longer term thing.

[Nick Culbreth]

actually it is +6 db of gain, even at 0 on the knobs, since I am running out of the XLRs.  But your right, the key reason to have it is Phantom Power, and in the cases where I need to boost one of the channels if I am off center to balance it out.

That being said, one of the things I am considering doing is getting a PS-2 and modding it to RCA outs, and trying that for a stint, but that is a longer term thing.

actually, the minimum gain when running xlr out is +16 db and +6 db when using the mini plug out.

[Todd R]

Hexy-

The analog dbu measurement that the MP2 lights indicate is different from the digital db (or more correctly dbFS -- decibels Full Scale) that is indicated on your A-D converter or your recorder. 

Nobody here will be able to tell you where to have the levels set according to the dbu scale of the MP2 as it will depend on the design specifics of your A-D converter (or recorder if you are using its internal A-D), which we don't know.  In general, the relationship between the dbu LEDs of the MP2 and the dbFS of your A-D will not be that readily understood, so you will be much better off setting your levels according to the A-D converter or recorder than you will be using the MP2's meters.  (And as you probably know, when setting against digital dbFS meters, you want to get as close to 0dbFS without going over as you can, though you might want to back it off a bit to give yourself some headroom.)

If you don't have the greatest meters on your A-D converter and/or your recorder, you can try to get a feel for where the levels should be according to the MP2 meters, but this will probably be a trial and error thing.  Unless you know what the input level requirements are for your A-D converter.  For instance, if I recall correctly, the V3 requires a 28 dbu signal level in order to meet 0dbFS when the V3 is set to provide 0db of gain.  So if you used a V3 and had the gain set to 15db, you would need to send a signal of no more than (but approaching) 13 dbu, which you could read off your MP2.  This info on the relationship of input strength (measured in dbu) to gain level and digital decibel level Full Scale may not be published for various recorders and A-D converters, so as I said, you're probably better off either using the meters on your A-D converter, or just doing some trial and error with your set-up to determine what gain level of the MP2 seems appropriate.

-Todd

Edit:  sorry, I didn't see before that the MP2 would be run with an SBM1.  Everything else above probably still stands, since I don't think sony has published the input requirements for the input signal strength level needed to reach 0dbFS, so you still won't know how much gain to run according to the MP2 level meters other than trial and error.

[hexyjones]

since the mp2 is an analog device, 0 dB is not the 0 dBFS that you're thinking of where clipping occurs in the digital domain.

Ahhh...thank you...

I'm under the impression that you want to achieve the highest amount of voltage (without clipping, of course) as early as possible in the signal path...? Shouldn't that be the guiding principle when using this device?

Is the light above each channels gain knob a clip light...? (on the MP-2)

[hexyjones]

Thanks for all the helpful replies...

I probably shouldn't have mentioned the SBM1...the question should have been...

"Without regard for any downstream deevices, how should one properly set the gain on an MP2?"

From a live sound perspective...if I'm setting up for a band...you tell the guy to hit the drum...you turn the gain knob till the red peak light comes on and then back it off until it's not coming on anymore. That is a properly gained channel right? You wouldn't want to run it low and gain it up later...you would just raise the noise floor...?

[nickgregory]

actually it is +6 db of gain, even at 0 on the knobs, since I am running out of the XLRs.  But your right, the key reason to have it is Phantom Power, and in the cases where I need to boost one of the channels if I am off center to balance it out.

That being said, one of the things I am considering doing is getting a PS-2 and modding it to RCA outs, and trying that for a stint, but that is a longer term thing.

actually, the minimum gain when running xlr out is +16 db and +6 db when using the mini plug out.

thanks for keeping me straight...I always mix it up !

[MattD]

"Without regard for any downstream deevices, how should one properly set the gain on an MP2?"

If you search this site for my username and mp2 limiter or something to that effect, you'll see a thread where I describe how to use the limiter on the mp2 to guarantee you don't clip your a/d or recorder. Though I wrote it for the stealthers, it applies to any mp2>?? combination, so this may be of interest to you as an mp2 user.

[scb]

didn't i write that and send it to you?