PT MBox 3 preamp levels too low?

[David Sandwisch]

Hi,

I am helping a friend diagnose his Mbox 3 as his audio levels seem too low coming into PT 9. I own PTHD2 on Windows XP and PT 7.3 but this is my first experience with the new Mbox and PT 9. I tested his system with his Royer condenser mic as well as an SM 57 and both seemed unusually low. Theoretically the Mbox has 74 db of gain according to the spec sheet but it certainly did not act like 74 db of gain. I had to have the gain up 90%+ to get the Royer to clip with a normal speaking voice, close miced.

I noticed that towards the very end of the gain range (turning the input knob almost all the way to the right) there is a very significant gain bump. If you are just under the gain bump, the level is too low compared to what I think it should be, if you go over the gain bump, the audio is way too hot with clipping. I have seen other preamps have gain bumps near the extreme end but nothing this drastic.

I would expect the condenser to be delivering healthy signals at about 50% gain on the Mbox but this was anemic in my opinion.

I could not find any software settings in PT 9 to control the sensitivity of the Mbox inputs. I was prefader metering, I did not have the -20 db pad engaged (knob was pushed in). There is no pad on the mic.

What is your experience, are the preamps this awful?

In HD I don't have this problem because I use external pres into line inputs on my I/O.

Thanks for your help.
David

[David Sandwisch]

Bump. Any ideas anyone? Are the new Mbox 3 preamps this terrible or is there a setting somewhere that I am not seeing in PT 9? I know I do not have the -20db pad engaged.

Thanks.

[chrisdee]

There is another guy with the same problem in this thread : http://duc.avid.com/showthread.php?t=289812

I would take the Mbox 3 Pro back to the store and test it against other Mbox 3 Pro's they have.

On my Mbox 2 Pro I have to turned the pot up to around 80-90% to get a healthy signal on my dynamic mic (SM7B). On my condenser and tube mic however setting the pot at 40-50% gives me a halthy signal. I would imagin the Mbox 3 Pro should be somewhat the same.

[David Sandwisch]

Yes I saw the other thread, that's why I already replied to it.

I miss spoke in my opening post. The Mbox 3 does not have 74 db of gain as I thought it did and only after close reading of the spec sheet and product sheet did I discover that Avid is misleading everyone!

I originally thought the Mbox had 74 db of gain if turned all the way up and then there was a - 20 db pad to cut hot levels into the preamp. This is how all other preamp / sound board manufactures give this spec that I have ever seen. But it is NOT what an MBox preamp REALLY does.

An MBox preamp only has 54 db of gain MAX that it can add to the signal coming in from the microphone. It is completely misleading for AVID to say it has 74 db of gain with the pad. The box CANNOT add 74 db of gain. It can ONLY add 54 db. Avid is saying if the signal is too hot coming in, you can drop it by -20 with the pad which effectively gives you a 74 db range of signal but really the SOURCE making the sound you are recording is giving you the first "20 db" and the the Mbox can add 54 on top of that.

This is completely misleading and makes people think they can ADD a lot of gain to make quiet recordings or if using a dynamic instead of a condenser in applications other than a loud snare drum or other high output source.

You cannot ADD 60 db of gain for example to a mic signal for a quiet recording of a soft spoken voice.

On top of this there is a very large gain bump towards the extreme setting of the dial. Other preamps I have see have this sudden increase in gain when you get near the top of the range but the Mbox's jump is bigger than any I've heard. Every bit of gain after the jump up is basically unusable as noise and everything increases.

So if the Mbox only has 54 db of REAL gain and perhaps the gain jump up at the end is say 6 db or so, the it REALLY only has 48 db of USABLE gain which is extremely LOW.

I would say the average amount of REAL gain on most sound boards and preamps is around 60 db with a very minor jump up at the extreme setting or no jump on great preamps. ALL other manufactures I have ever seen give the amount of gain that the preamp ADDS and then say there is a pad if one is available. I have never seen a company then say there is x gain + pad for Y amount.

For example if APB-Dynasonics says there Spectra board has a preamp with a minimum gain of 10 db and a maximum gain of 65 db with a pad that can be inserted to drop it -20, they mean there is 65 db of gain the board can ADD to the mic signal. Not 65 + 20 = 85 db which is the funny math Avid is using. APB would never say their preamp has 85 db of gain because it can only ADD 65 db max to the input signal.

It makes sense to me, just think about the logic and realize Avid is misleading people with there product literature. Basically Avid never says it ADDs 74 db of gain. They say it has a 74 db "range" which is a true statement but every other preamp manufacture does not give the "range" available, they say what the maximum amount of gain a preamp can ADD. It's semantics and while Avid isn't lying on their literature, they definitely are misleading people.

[chrisdee]

Originally Posted by David Sandwisch

Basically Avid never says it ADDs 74 db of gain. They say it has a 74 db "range" which is a true statement but every other preamp manufacture does not give the "range" available, they say what the maximum amount of gain a preamp can ADD. It's semantics and while Avid isn't lying on their literature, they definitely are misleading people.

I agree. It's a bit confusing and misleading.

[dalebu]

This is absolutely horrifying. I have the same problem.
I plugged in AKG C568B (condenser boom mic), turned the gain knob all the way to the right
and I can't get the signal to clip while speaking normally, half meter distance from mic.

Tell me there is some hidden button or a small latch...

[jbasil]

Make sure you have the mBox Control Panel software configured properly. It would be great to be able to bypass this and go right from the mBox into PTools, the way PT usually is, but I don't think it's possible. The Control Panel is the only way to set up the box, and even when it is not open it's the controlling layer for the box and its DSP before the signal goes to PT.

The unit I have worked with gets very healthy signal and sounds excellent, wonky as the software is.

[albee1952]

Have you pushed the GAIN knobs IN to turn off the 20db pad?

[browniespeaks]

why are you guys trying to clip your converters? If you have healthy signal you may increase the gain inside protools with the audio sweet plug it will also gain match another segment of audio if you want.

My Mbox3 mini sounds on par or better than any of the pro sumer pres i have worked with recently. It doesnt flavor like classics but I'm not sure what you consider low levels. are you compairing your levels to the noise floor or to other mics and pre combinations?

[robo6675]

I think I good question to ask here is what kind of levels are too low? Are you trying to get as close to red as possible? There's no need to do that at all. Yellow is the new red. You can easily make up the last 6 db or so when you enevitably compress the vocal. Better to have a non clipped signal than to have louder source.

In all fairness, I've noticed this low gain thing having owned a mbox1, mbox 2 pro and a 003. It's pretty safe to say that the preamp quality helps keep the price of their hardware down. I say work with it, get another preamp or return it and get a converter with higher quality preamps built in.