Topic: Overload indicators (Sonosax / SBM-1)

[tchoub]

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

[Brian Skalinder]

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.

[tchoub]

thanks Brian.
+T for the detailed information.

[Tim]

Brian nailed it.... you're doing fine

[bagtagsell]

its an art to get that sbm1 flickering, but not staying on. 

[bagtagsell]

same concept.  -2 on sbm -3 on ua5.  Its like learning to drive a stick shift.

[Brian Skalinder]

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.

[dgale]

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? 

[hexyjones]

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....

[Brian Skalinder]

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.

[hexyjones]

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...?

[Brian Skalinder]

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.

[hexyjones]

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...

[tchoub]

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 

[hexyjones]

You might find this handy

http://www.sweetwater.com/store/detail/LLS2/

Perhaps this is the kind of device Brian was refering to...