+4dBu to -44 dBu - Can someone explain this.

A

AndyK12

New member
I was looking online at the specs for my AW2400 because I've rented a preamp with -60 dB of gain because I'm not able to get my dynamic SM57 anywhere near -6 dBFS for tracking purposes (pretty loud electric guitar) with the built in preamps on my unit. However even with the other preamp cranked it still won't push the signal anywhere close to that. I've got the rented preamp going to my machine through the built in preamp on my machine.

Looking at the specs for the AW2400 the gain on the built-in preamp is listed as +4 dBu to -44 dBu. Does that mean when I've got the preamp on my AW2400 off (rotated to the 'line' position @ +4dBu) it's actually attenuating the incoming signal by 4 dB?

Any advice I'd like to hear, and yes, I realize I could just turn the preamp on the AW2400 up as well to get more gain but I'd like to know what's going on here, and where that bugger of a knob has to be set to achieve a unity setting.

Thanks,
Andy
 
AndyK12 said:
I was looking online at the specs for my AW2400 because I've rented a preamp with -60 dB of gain because I'm not able to get my dynamic SM57 anywhere near -6 dBFS for tracking purposes (pretty loud electric guitar) with the built in preamps on my unit. However even with the other preamp cranked it still won't push the signal anywhere close to that. I've got the rented preamp going to my machine through the built in preamp on my machine.

Looking at the specs for the AW2400 the gain on the built-in preamp is listed as +4 dBu to -44 dBu. Does that mean when I've got the preamp on my AW2400 off (rotated to the 'line' position @ +4dBu) it's actually attenuating the incoming signal by 4 dB?

Any advice I'd like to hear, and yes, I realize I could just turn the preamp on the AW2400 up as well to get more gain but I'd like to know what's going on here, and where that bugger of a knob has to be set to achieve a unity setting.

Thanks,
Andy
Click to expand...

1.You don't need to print that hot, especially with 24 bit conversion. Anywhere between -18 to -12 will do just fine.
2. This unit has 2 dedicated line inputs on trs phone jacks. Bring the outboard preamp in via one of them.
 
Last edited:
Thanks RRuskin,

those are good suggestions as far as tracking levels, and putting the preamp through the dedicated line in's.

I'm still clueless on the how to read the spec +4dBu to -44dBu.

Does that mean + 4dBu is attenuating the signal by 4 dB? I went to audio school (not that THAT means much) but I've never seen a preamp measured with a positive dBu rating. If I'm not mistaken if I sent a +4dB signal to the preamp and set my preamp at +4dB that would actually be causing the preamp to knock 4 dB off of the incoming signal? Right? Maybe? Hello?

Thanks, I'm sure it just means you've got a swing of 48dBu to work with, but that's not quite enough for my dynamic microphones.

Andy
 
They're saying, for 'INPUT [1-8]' with 'Gain' set 'Min' a +4dBu signal (1.23Volts) = 'Nominal' (that generally means what they consider center for good operating range), and a "+18dBu (6.16V) clip point. That's you head room for peaks above 'nominal.
At 'Max' Gain setting a -46dBu (3.88mV) signal gets you back to the same with -32dBu (19.47mV) clip point.
Now, it would be good to know, if nothing other so you'll know when you see it on the record meters, where a '+4 at min' lands. It's apt to be -18 or so below full scale(?)

I didn't look but lots of times they'll have a gain or voltage level flow chart. That would be another way to see their gains/losses throughout the machine.
 
Thanks mixsit.

I'll e-mail yamaha and ask what the nominal range is, I think it'd be a good thing to know. I'm having to set the preamp all the time to the max (with the noise floor going WAY up and making the signal unusable) and use alot of 'makeup gain' inside of the machine digitally. I'd prefer just to be able to get a hot clean signal right off the hop without having to jack the onboard compressor's output by -13dB to achieve any sort of workable signal.

Thanks again.
 
Hey Andy, I think you're focusing too much on the amp specs and not enough on the real issue...

What's wrong with your signal chain that a 60 dB preamp isn't enough to provide enough gain for an SM-57 miking a guitar cab? You really shouldn't need a high gain preamp (The 57's a dynamic, but it's not dead... or is it?) to track a cabinet through a dynamic.

You don't need a high gain preamp, you need to fix the problem
 
Last edited:
AndyK12 said:
I'd prefer just to be able to get a hot clean signal right off the hop without having to jack the onboard compressor's output by -13dB to achieve any sort of workable signal.
Click to expand...

With a heavily distorted electric guitar, -20dBFS is a workable signal.
 
+4 dBu to -44 dBu are simply line and mic levels respectively. Line level is anywhere from -10 to +4VU; mic level can go all the way down to -60VU.

I agree with MOFO though...dude, 60dB of gain should be PLENTY...should be way more than you need, actually. Something else is wrong here.

Frank
 
You must log in or register to reply here.
Back
Top