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Gear / Technical Help => Ask The Tapers => Topic started by: tchoub on March 19, 2005, 06:17:35 AM
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Hello,
I just made my first recording yesterday with my new sx-m2 and sbm-1.
I was recording from the soundboard so my setup was :
sbd > xlr outs > sx-m2 (xlr ins ; 0dB) > line out > sbm-1 (line in) > d8.
I got the overload indicators of the sbm-1 flash on both channels a couple of times but the sx-m2 overload indicators never went on.
After transfering the dat to my computer, I opened the wav file in soundforge and noticed that the sbm-1 overload indicators go on at 1-2 dB before clipping point.
Does anyone know why the sx-m2 overload indicators didn't blink on the "loud parts" that is to say when I had the sbm-1 overload indicators go on ?
Is it due to a difference between analog material and digital material ? Maybe related to a difference in the definition of the clipping point ?
By the way, I had the sbm-1 overload indicators go on more that 2 seconds one or two times during the recording (OVER appeared on the D8) and I can't hear any distorsion.
Do you have any hints ?
Thanks
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All is well, you're running the gear appropriately and it appears to be functioning properly.
You're correct in that the SBM-1 "over" lights trigger at roughly -2dB. And you also have it right: the "over" indicators on the Sax and SBM-1 represent two different types of overloads - one in the analog domain, Sax, one in the digital domain, SBM-1. Overloading either is bad news, but you'll be hard pressed to overload the Sax, IME. And occasionally flickering the SBM-1 lights is good, means you're getting nice strong levels - just make sure you don't peg the "over" light too long or you'll clip in the digital domain.
As for the D8's levels...I vaguely recall that the SBM-1 "over" lights are true digital meters while the D8's are analog and therefore not as accurate. Bottom line: use the SBM-1 to set your levels and don't sweat the D8 meters.
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thanks Brian.
+T for the detailed information.
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Brian nailed it.... you're doing fine :)
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its an art to get that sbm1 flickering, but not staying on.
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same concept. -2 on sbm -3 on ua5. Its like learning to drive a stick shift.
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same concept. -2 on sbm -3 on ua5.
And the SBM-1 has two indicators, L and R, while the UA5 has a single indicator.
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By the way, I had the sbm-1 overload indicators go on more that 2 seconds one or two times during the recording (OVER appeared on the D8) and I can't hear any distorsion.
Since it seems that you just barely clipped the signal, the resultant distortion is not likely audible (but technically is there). You need to peg the levels either higher and/or for a more sustained period of time to hear audible distortion. That being said, the signal is still compromised when you clip, so the game is to try and get the levels as high as possible while not clipping...don't be afraid to have a few brief/small clips - I personally would much rather do this and otherwise have a nice strong signal then be timid and run the levels at -12db all the time like I see so many folks do. With a Sbd feed, these brief clips are usually a loud cymbal crash or somethng like that and are usually no big deal - if the feed itself gets that loud in general, you will notice the levels themselves creeping up too high and not just a sudden/brief clip.
I am curious what benefits folks find in running a Sbd feed into a pre-amp and not just straight into the A/D?
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By the way, I had the sbm-1 overload indicators go on more that 2 seconds one or two times during the recording (OVER appeared on the D8) and I can't hear any distorsion.
Since it seems that you just barely clipped the signal, the resultant distortion is not likely audible (but technically is there). You need to peg the levels either higher and/or for a more sustained period of time to hear audible distortion. That being said, the signal is still compromised when you clip, so the game is to try and get the levels as high as possible while not clipping...don't be afraid to have a few brief/small clips - I personally would much rather do this and otherwise have a nice strong signal then be timid and run the levels at -12db all the time like I see so many folks do. With a Sbd feed, these brief clips are usually a loud cymbal crash or somethng like that and are usually no big deal - if the feed itself gets that loud in general, you will notice the levels themselves creeping up too high and not just a sudden/brief clip.
I am curious what benefits folks find in running a Sbd feed into a pre-amp and not just straight into the A/D?
In this case - he had an XLR board feed...pro level - probably better put the SAX in there (a better match for the pro/XLR out)...and then feed the consumer line level signal to the SBM1 from the UA5
But I see your point...
EDIT: Sorry changed UA5 to SAX...I'll just shut up....
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I am curious what benefits folks find in running a Sbd feed into a pre-amp and not just straight into the A/D?
Adds color - most folks like the sonic signature of their preamp. And some ADCs don't have good level controls. Or if one forgets or doesn't have XLR > RCA adapters.
In this case - he had an XLR board feed...pro level - probably better put the UA5 in there (a better match for the pro/XLR out)...and then feed the consumer line level signal to the SBM1 from the UA5
And therefore run AD (UA5) > DA (UA5) > AD (SBM)? Doesn't make sense to me when one could just run XLR > XLR/RCA adapter > SBM-1 line-in.
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But Brian - if the SBM 1 wants to see a -10db signal and you feed it a +4db signal - arent you inviting brickwalling...?
By XLR > RCA - do you mean an active device that actually reduces the signal strength...?
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But Brian - if the SBM 1 wants to see a -10db signal and you feed it a +4db signal - arent you inviting brickwalling...?
The UA5 specs: nominal input 1/2 (-50 - 0 dBu), input 3/4 (-10 dBu). I don't know if the SBM-1 accepts +4 or -10, but I'd guess -10. So, if fed a +4 signal, regardless which device you use, you're inviting brickwalling. Only real solution: ask the sound engineer to turn the levels down for you. Problem solved.
By XLR > RCA - do you mean an active device that actually reduces the signal strength...?
Passive adapters.
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But Brian - if the SBM 1 wants to see a -10db signal and you feed it a +4db signal - arent you inviting brickwalling...?
The UA5 specs: nominal input 1/2 (-50 - 0 dBu), input 3/4 (-10 dBu). I don't know if the SBM-1 accepts +4 or -10, but I'd guess -10. So, if fed a +4 signal, regardless which device you use, you're inviting brickwalling. Only real solution: ask the sound engineer to turn the levels down for you. Problem solved.
By XLR > RCA - do you mean an active device that actually reduces the signal strength...?
Passive adapters.
Arent you inviting more noise by just turning it down...?
Only real solution - use a device that can handle a pro-output...
EXAMPLE : My old Marantz CD-R 610 had a switch on the back. -10db or +4db, depending on what kind of signal you were feeding it...if I had an XLR feed - set it to +4 ---If I had an RCA feed - set it to -10...
I think there is a "right" way to do this and not just some hack, or "whatever" works...
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the main reason of using the sax was that I only had a 1/8" > 2RCAs cable while the soundboard only had xlr outs...
and the sax is a very nice preamp IMO so I just use it every time I can :D
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You might find this handy
http://www.sweetwater.com/store/detail/LLS2/
Perhaps this is the kind of device Brian was refering to...
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Perhaps this is the kind of device Brian was refering to...
As I indicated in my follow-up post, I was referring to passive adapters.
I think there is a "right" way to do this and not just some hack, or "whatever" works...
Ideally, of course we want to feed a device that accepts a +4dBu signal. But not all of us have gear that accepts a +4 signal.
Arent you inviting more noise by just turning it down...?
If the options are: [1] brickwall, or [2] ask the sound engineer to lower the output (assuming this does introduce noise - which I'm not convinced it does) and suffer a bit of noise in the recording ($5 says no one here would hear it if it even exists), then [2] obviously makes more sense.
Only real solution - use a device that can handle a pro-output...
Given the context of the discussion - devices that accept a -10dBu signal (SBM-1 / UA5, from your suggestion of running (UA5 analog-out > SBM-1) - yes, the solution I proposed is the only real-world, practical solution to ensure brickwalling does not occur.
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the main reason of using the sax was that I only had a 1/8" > 2RCAs cable while the soundboard only had xlr outs...and the sax is a very nice preamp IMO so I just use it every time I can :D
And, turns out it's the right decision to prevent brickwalling the SBM-1 by feeding it the board signal directly: the Sax XLR inputs accept a +6dBu (max +20dBu) signal.
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Edit: note sorry I switched SAX with UA5 - getting my threads confused...
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From the Sonosax manual:
9. GAIN SELECTOR
The gain switch has three positions. The center position ensures the 0dB gain (unity gain). In this case, the output level is equal to the input level. This could be of help when the SX-M2 is used as an impedance adapter, or a balanced line driver. The "LO" gain position allows 6dB to 40dB gain, and the "HI" gain position, 20dB to 76dB.
You did it exactly right...IMO
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Edit: note sorry I switched SAX with UA5 - getting my threads confused...
Doh! lol I should've caught it, too.
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I often have run Sbd>SBM-1 with some XLR>RCA cables - you lose the balanced signal (which you do anyway when you run pre>SBM-1) but I've never had a problem with brickwalling with the SBM-1 and a XLR Sbd feed, while I definitely have trying to run the same feed straight into a Sony portable DAT. I always used the rule of thumb that if the SBM-1 had levels set to less then 4 then I would turn down the feed at the Sbd. I resolved all of this by lugging along my R500 to shows - I can run XLR straight into it, use SBM, and have a lot more confidence in that deck then I do in a sony portable. Of course it is a pain to lug that thing around but it's never failed me. I learned that trick from Bob Daniels (Hot Tuna), who has a rollaway with a R500 and a R300 in it. That amount of gear is probably not going to go over well unless you are in good with the venue and/or band but it is definitely bullet-proof. Of course once I got a taste of Sbd>AD2K+ @24/48>laptop, the 16bit DAT became a never-listened to back-up anyway.
Anyway, intersting discussion - I have an MP-2 and have never considered using it for anything but driving my KM140s.