Preamp - Compressor Relationship

[PRHunt]

So what is the difference besides it the level being softer or louder?

On my Echo Audiofire8, selecting -10dBV on the inputs causes the unit to apply a digital signal boost after conversion. This is in the order of 12dB, which brings the signal up to a nominal +4dBu. (On the Audiofire range, this selection is made via the software console).

Your converter may be doing a similar thing? If you have your unit set to expect a signal at -10dBV (nominal), but the signal you feed it is actually at +4dBu (nominal), then you could be actually inducing an unwanted boost of about 12dB.

You'll find it worthwhile to do a search on dBV and dBu. The -10dBV standard ("consumer") is a average lower voltage signal than +4dBu ("pro", which is approx 12dB or 4x higher ). You should generally leave everything at +4 which is the standard nominal signal voltage for "pro" equipment.

If a switch if for "pad", it will generally be clearly labeled as such.

Paul

 

[bdenton]

I Actually Had An Mbox 2 Mini

And here's how you do it on the Mbox 2 Mini...

Set your compressor aside for the moment; leave it out of the signal chain.

Plug your preamp into one of the 1/4" inputs on the Mbox. If your preamp has a balanced output, use a balanced-to-unbalanced cable (TRS/XLR to TS).
Turn the "gain" knob on your preamp all of the way down.
Engage the 20db pad (button in). Turn the gain knob for that input (on the front of the Mbox) to about the one o'clock position.

Plug your mic into your preamp and, while singing into the mic, gradually increase the gain on your preamp until you are getting the correct level in Pro Tools.

Turn off the power to the preamp and Mbox.

Disconnect the balanced-to-unbalanced cable from the preamp output. Connect the output of the preamp to the input of the compressor with a balanced cable, and use the balanced-to-unbalanced cable to connect the compressor to the Mbox.

Adjust the compressor as desired. If necessary, turn down the gain on the Mbox to maintain the correct level in Pro Tools.

The "larger" Mbox units do offer some unbalanced true line-level inputs, the Mbox 2 Mini does not.

On the Mbox 2 Mini, no matter whether you are plugging into the XLR jack or into one of the 1/4" jacks, the signal goes through the preamp. And the preamps are really hot!!! When I plugged my "vintage" Squire Tele directly into one of the inputs I had to use the 20db pad if I wanted a "clean" tone; without it I got what was actually some very sweet distortion.

Sorry you spent the major bucks on the preamp and compressor, but there is no way to avoid using the Mbox 2 Mini preamps. But for the moment, the best idea is probably to set them aside until you are able to buy a better interface/converters, and use one of Pro Tool's plugin compressors.

Good luck...

 

[bouldersoundguy]

So what is the difference besides it the level being softer or louder?

The -10 setting doesn't lower the signal relative to the +4 setting, it effectively increases it, which seems to be the exact opposite of what you're expecting and how you're using it.

 

[timkroeger]

So I checked the specs for the Mbox and the 1/4' DI ARE meant for instruments.
Also the inputs are unbalanced. So I'm guessing that means it doesn't have a true balanced line level input.

I've also discovered that there is no way to bypass the internal pres of the mbox. Is this also presented a problem for me?

That just might be your "problem". You might not have the correct settings on the back of your mbox mini (if it is an mbox mini). If it is an Mbox 2 mini, listen to bdenton. It really depends on the type of interface you own.

I'm assuming you're having the Mbox mini (not Mbox 2 mini): Going with a line level +4dB signal (or at least one half of it) into instrument DI ist just too much signal. Either use the 01 XLR/TRS combined Mic/Line input or the 02 Line/DI input and have the corresponding switch at the line position. I'd suggest using the 02 input switched to line level as you can't accidentally engage the phantom power. It's a 1/4" TRS (tip-ring-sleeve) balanced jack you you shouldn't need to be forced to engage the pad.

I don't know of it's hard to disconnect the comp from the chain but I'd test without the comp first. Is there any possibility of introducing level matching issues (+4dBu balanced to -10dBV unbalanced) from pre to comp by wrong wiring? Definitely use balanced cabling between pre and comp.

Cheers
Tim

 

[bdam123]

Wow, thanks guys for all the info. I'm actually using an Mbox 2 Mini but I'll be converting to one of the new Mbox Pros in a week or so as an upgrade for my A/D conversion.

bdenton, can I follow the same steps you described for my new unit?

Also, this is a little off topic but I was looking at getting a stand along A/D unit like the Lavry Black AD-10 but it was a little out of my budget right now. I was wondering how much of a difference that will make it my chain compared to just using the Mbox Pro's A/D converter. Thanks guys.

 

[PRHunt]

Also, this is a little off topic but I was looking at getting a stand along A/D unit like the Lavry Black AD-10 but it was a little out of my budget right now. I was wondering how much of a difference that will make it my chain compared to just using the Mbox Pro's A/D converter. Thanks guys.

Can I humbly suggest that rather than investing lots of money in new gear, you instead invest time into thoroughly understanding your current gear and getting the best from it?

You seem to have had some significant hassles working out a gain-staging issue with your current kit, so it seems to me that stressing about converters is not where you need to be right now.

Anyway, if I've misread your situation, I'll pull my head in now.

 

[RAMI]

Can I humbly suggest that rather than investing lots of money in new gear, you instead invest time into thoroughly understanding your current gear and getting the best from it?

You seem to have had some significant hassles working out a gain-staging issue with your current kit, so it seems to me that stressing about converters is not where you need to be right now.

Anyway, if I've misread your situation, I'll pull my head in now.

i agree 100%. I wasn't going to say anything because I didn't want to come off like a party-pooper. But, seriously, one of the last things you should be worrying about right now is A/D converters. All this investing in equipment can have much better results if at least a small (and it really should be a BIG) percentage of it was spent on room treatment.....and learning how to use the equipment you already have. Not trying to come off heavy, just giving my opinion.

 

[bouldersoundguy]

I'm with PRHunt and RAMI. See my post above and tell us if you understand what -10 and +4 mean. If you don't get it you're troubles will follow you whatever gear you buy. Have you even bothered to try the +4 setting, or are you still convinced that -10 is a pad setting?

 

[Chili]

Also, this is a little off topic but I was looking at getting a stand along A/D unit like the Lavry Black AD-10 but it was a little out of my budget right now. I was wondering how much of a difference that will make it my chain compared to just using the Mbox Pro's A/D converter. Thanks guys.

Half of my stuff is done with Lavry Black, the other half with a Phonic firewire mixer, complete opposite extremes. You aren't going to tell the difference. There are so many other variables that will shape the quality of your recording before the converters come into play.

Spend your money on room treatment, monitors, mic and pre-amps. That order.

cheers,

 

[moresound]

Heavy stuff guys.

 

[SouthSIDE Glen]

Telefunken AK-47 microphone: $1,695
Brent Avril 312a Series 500 Preamp: $760
API 527 comp/lim: $845
Getting one's paws on $3300 worth of botique-quality, pro-level signal chain and heading to a home recording forum to find out how it works: Priceless

There are some things money can't buy. For everything else there's Mastercard.

G.

 

[moresound]

Telefunken AK-47 microphone: $1,695
Brent Avril 312a Series 500 Preamp: $760
API 527 comp/lim: $845
Getting one's paws on $3300 worth of botique-quality, pro-level signal chain and heading to a home recording forum to find out how it works: Priceless

There are some things money can't buy. For everything else there's Mastercard.

G.

Shhhhh..... Glen maybe he'll sell it to us on the cheap if we convince him that a good USB microphone to his sound card is the way to go!

 

[bdam123]

Touche. Thats the exact reason I came here. To learn as much as I could. I'll be recording stuff that I'll be putting it out along with demos for real artist that has to sound its best. Unfortunately being a producer and songwriter these days mean you have to work the whole process. I started as a guitarist, turned into a music programmer/producer into a mixer and now I'm a recording engineer. Its fair that you guys make whatever assumptions you wish but the truth is I got tossed in with the sharks and I'm gonna make the best of it and that includes trying to ask questiona and learn from people that know.

Either way I've gained a lot of insight from this thread. So thanks to the ones that helped out. I'm gonna be rereading everything in here along with articles I've been saving and attack my chain at the end of the week.

@bouldersoundguy I do understand the difference between -10 and +4 now. Need to do more research in general. I'll be back. Thanks.

 

[moresound]

Touche. Thats the exact reason I came here. To learn as much as I could. I'll be recording stuff that I'll be putting it out along with demos for real artist that has to sound its best. Unfortunately being a producer and songwriter these days mean you have to work the whole process. I started as a guitarist, turned into a music programmer/producer into a mixer and now I'm a recording engineer. Its fair that you guys make whatever assumptions you wish but the truth is I got tossed in with the sharks and I'm gonna make the best of it and that includes trying to ask questiona and learn from people that know.

Either way I've gained a lot of insight from this thread. So thanks to the ones that helped out. I'm gonna be rereading everything in here along with articles I've been saving and attack my chain at the end of the week.

@bouldersoundguy I do understand the difference between -10 and +4 now. Need to do more research in general. I'll be back. Thanks.

At a boy bdam the key is to read as much as possible as you have figured that out and this sight is damn good to learn on. Then do as much recording as possible and learn from your mistakes and eureka moments.


Now on the sale of your gear.

 

[bdam123]

At a boy bdam the key is to read as much as possible as you have figured that out and this sight is damn good to learn on. Then do as much recording as possible and learn from your mistakes and eureka moments.


Now on the sale of your gear.

Yea, I always learn a lot on here. Haha we put ourselves in poor house with our acquisitions. We'd sell our souls first. Yea I'm gonna go back over all this stuff when I get some time to focus on the chain. I will be back her asking more questions without a doubt haha.

 

[bdam123]

Ok, so after getting the shit beat out of me I've come to the conclusion that there is a good chance the the Mbox 2 Mini is operating at -10db. Although there is no where in the manual or the specs that state this.

So is running a Telefunken -- BAE 312 -- API527 pretty much going to guarantee that I'm going to be coming in super hot? Cause thats totally whats happening.

Also when I start trying to turn things down, either by engaging all available pads or turning down output knobs the signal just doesn't sound good. The only level where I can get that nice clear sparkle is when I'm literally about to clip in PT.

Someone mentioned this earlier in the thread and I'm about convinced that my problem lies in the Mbox. Am I right?

If so, any tips? I know I can still record with a hot signal as long as its not clipping but I also know its not optimal.

Thanks again for bearing with my newbness and blessing me with guidance. Peace.

 

[PRHunt]

Here are some specs I managed to find for the mbox2 mini:

Input Sensitivity, Pad off: +1 dBu minimum gain, -52 dBu maximum gain
Input Sensitivity, Pad on: +21 dBu minimum gain, -32 dBu maximum gain

These tell me that, with the pad engaged, your mbox2 mini should handle an input signal of +21dBu with the mbox2 gain knob at minimum. A signal of that size will likely result in a digital output which is close to full scale - so you will get close to 0dB in protools.

(The pad switch on the mbox2 reduces the input signal by 20dB)

Now, +21dBu is about 8.7Vrms (approx 24V peak to peak) - a pretty hot signal.

If the sound you want is delivered only by cranking the pre and the comp, then as far as I can see, you will need to reduce the signal just before it reaches the mbox. Maybe you could do that with an inline pad between the comp and the mbox. That way, the signal should be coloured the way you want, but just less hot when it reaches the mbox.

Note: you do need the pad switch on the mbox turned ON.

Hope this helps..