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Gear / Technical Help => Battery Boxes, Preamps, Mixers, ADCs, and Processors => Topic started by: busknuckle on February 04, 2004, 05:52:47 PM

Title: A/D + preamp question
Post by: busknuckle on February 04, 2004, 05:52:47 PM
So I'm getting my SBM back soon from being modded, and I'm going to be using it with an mp2 this month. This will be the first time I've run a pre with an external a/d.

Can someone either:

- point me to where I can get the info

or

- Give me some info on this:

What is the correct way to run the gain here? I've heard that you should crank the gain on the SBM-1 and run the pre low, but I've also heard the opposite. Is there no wrong answer?...is it purely based on personal choice?
Title: Re:A/D + preamp question
Post by: Craig T on February 04, 2004, 06:01:05 PM
I'd set the sbm1 at 8 or 9 and add gain on the MP2 to get good levels.  That still gives you a little room on the sbm1 to fine adjust if necessary.
Title: Re:A/D + preamp question
Post by: Tim on February 04, 2004, 06:05:32 PM
remember the SBM-1 is not applying gain, it is a resistor and as such should be run as wide open as possible.
Title: Re:A/D + preamp question
Post by: nickgregory on February 04, 2004, 06:19:01 PM
I'd set the sbm1 at 8 or 9 and add gain on the MP2 to get good levels.  That still gives you a little room on the sbm1 to fine adjust if necessary.

I have found that most shows, the most I can get the Mod SBM-1 to is the 6-7 range, even with the MP-2 all the way down on the levels...
Title: Re:A/D + preamp question
Post by: dmonterisi on February 04, 2004, 06:32:07 PM
remember the SBM-1 is not applying gain, it is a resistor and as such should be run as wide open as possible.

are you sure about this?

when people run m148>sbm1, where does all the gain come from?  they're not just running 20db's of gain are they?  this just seems weird to me.
Title: Re:A/D + preamp question
Post by: Tim on February 04, 2004, 06:42:12 PM
hmmm.... I think I should rephrase that.

damnit, I'm that guy they were talking about over at Oade.
Title: Re:A/D + preamp question
Post by: dmonterisi on February 04, 2004, 06:46:14 PM
i quickly looked over the sbm manual in the archive here and could not find any reference to adding gain...but sony's manuals are always simplistic and do not carry all useful info.
Title: Re:A/D + preamp question
Post by: super-phat-al on February 04, 2004, 06:50:44 PM
+T on the SBM-1>mp2 combo.  I love that combo.  Hello BASS
Title: Re:A/D + preamp question
Post by: Todd R on February 04, 2004, 07:11:45 PM
Tim's almost got it.  The SBM1 provides a fixed gain and then levels are set post gain by running the signal through a variable resistor (or maybe signal first goes through the variable resistor, and then onto the fixed gain stage, can't quite remember at this point).  So run the SBM1 at 10 and the signal effectively doesn't go through the resistor.

It all depends on how your ears hear things, but theoretically it will be best to run the mp2 low and the SBM1 close to wide open.  Less signal degradation within the SBM1's variable resistor this way, and less gain applies at the mp2, whose gain stage gets worse at higher levels of gain, at least IMNSHO.

-Todd
Title: Re:A/D + preamp question
Post by: Tim on February 04, 2004, 07:13:26 PM
thanks Todd, perhaps I should just stay out of the tech talk and stick with making wiseass comments in the open forum. see you tomorrow!
Title: Re:A/D + preamp question
Post by: busknuckle on February 04, 2004, 08:28:53 PM
+T on the SBM-1>mp2 combo.  I love that combo.  Hello BASS

I wish I could say that the mp2 was mine...but I'm borrowing it for the show (from a member of this board...thanks again Steve!)

Another coolio member has graciously consented to letting me try out his Octava MK319's (thanks Jonny)

Thanks for the good info people.
Title: Re:A/D + preamp question
Post by: zhianosatch on February 04, 2004, 08:40:00 PM
Bill, more important than sound quality debates is are you stealthing or not? That should dictate how you run the combo first, then see what you can do about tweaking for smidgens of better sound.
SBM wide open sure is clean......
Title: Re:A/D + preamp question
Post by: scb on February 04, 2004, 09:08:53 PM
for stealthing, i highly recommend the mp2 limiter.  it allows you to "set it and forget it" like that guy on the rotisserie oven infomercials who looks like he's got a rubber face

set the limiter so it's a hard limit (kicks in right as it overloads) and then set your deck (or sbm) so that that highest level the mp2 gives out is -2 on your dat.  then tape the knob down on your dat or sbm there.  

then, during the show, you use the mp2 knobs for gain.  you absolutely *cannot* clip this way because the mp2 will do a hard limit at -2 on your deck.  but don't run too hot either, or you'll compress it a bit too much.  

i've learned to LOVE this because I can set levels during the first tune and be done.   even if they crank the volume, i know i'm no clipping, and i never have to look at the deck (can't get caught).   the hard limit also assures you that you won't be limiting unless it's really hot (would have clipped if the limiter wasn't on). for most of the show it'll be the pure signal

i just wish i hadn't screwed up the calibration for the bruce & friends show in december...woops.  
Title: Re:A/D + preamp question
Post by: busknuckle on February 04, 2004, 10:08:39 PM
Good to know but this will be an open taping situation. It would be hard to stealth those LD mics.
Title: Re:A/D + preamp question
Post by: Chapper on February 06, 2004, 03:12:43 PM
for stealthing, i highly recommend the mp2 limiter.  it allows you to "set it and forget it" like that guy on the rotisserie oven infomercials who looks like he's got a rubber face

set the limiter so it's a hard limit (kicks in right as it overloads) and then set your deck (or sbm) so that that highest level the mp2 gives out is -2 on your dat.  then tape the knob down on your dat or sbm there.  

then, during the show, you use the mp2 knobs for gain.  you absolutely *cannot* clip this way because the mp2 will do a hard limit at -2 on your deck.  but don't run too hot either, or you'll compress it a bit too much.  

i've learned to LOVE this because I can set levels during the first tune and be done.   even if they crank the volume, i know i'm no clipping, and i never have to look at the deck (can't get caught).   the hard limit also assures you that you won't be limiting unless it's really hot (would have clipped if the limiter wasn't on). for most of the show it'll be the pure signal

i just wish i hadn't screwed up the calibration for the bruce & friends show in december...woops.  
Very interesting as I use the MP2 for stealth all the time.   What happens to the signal when it hits the limiter?  Is it audible.  I've heard some of your stuff, so I'm assuming it's not audible.  
Title: Re:A/D + preamp question
Post by: scb on February 06, 2004, 03:39:02 PM
>>What happens to the signal when it hits the limiter?  Is it audible<<

it's just compressed a little and not allowed to get any hotter.  it's the same as running a soft limit on the minime or ad1000.  it'll stop overs.  you won't hear it if you run the levels correctly

if you run way to hot and rely on the mp2 limiter to keep it below clipping, then you'll hear it.  too much compression can make the high end sound very harsh, but if you run it as usual and let the limiter stop the occasional overs, you'll be fine.  hope i'm making sense.  

basically it allows you to run a little hotter than you'd normally run at a stealth show because you know that any occasional overs that you might hit will be stopped from being overs.