+4 vs -10 : how do i use +4????

[davefromfade]

I've read a great deal about +4dbu and -10dbv. My console supports
both as well as my M-Audio Delta 44 soundcard. Everything I've read says you want to be using +4 since this has more headroom and less sensitivity (more room to play with the dynamics) than -10. However, when I set my soundcard to +4 output and my mixer as +4 on the input from the soundcard output and PFL the channel, my mixer shows a continuous clip light which registers over +10dbu. So, can someone explain the difference between the two and how I achieve a +4 environment with the equipment I have. I think there is just something that I am missing here.

 

[reshp1]

I've read a great deal about +4dbu and -10dbv. My console supports
both as well as my M-Audio Delta 44 soundcard. Everything I've read says you want to be using +4 since this has more headroom and less sensitivity (more room to play with the dynamics) than -10. However, when I set my soundcard to +4 output and my mixer as +4 on the input from the soundcard output and PFL the channel, my mixer shows a continuous clip light which registers over +10dbu. So, can someone explain the difference between the two and how I achieve a +4 environment with the equipment I have. I think there is just something that I am missing here.

Are you pluging the soundcard out into the preamp/mic in on the mixer, oure are you using the "LINE IN?" Also, turn the trim/gain knob on your mixer channel all the way down.

 

[davefromfade]

i'm plugging the sound card outputs in to a stereo line input in my mixer (channels 9/10), which has a -10/+4 switch at the top, no trim knob.

i recognize your icon from a picture i saw on an ebay ad for an alesis dm5!

 

[mshilarious]

+10dBu shouldn't clip a +4 mixer. Clipping should be more like +22 dBu or more. Given that 0dBFS is probably +19dBu, I don't think it's surprising that your meter reads +10dBu.

 

[davefromfade]

it's way beyond +10. that's the highest reading on my meter before the clip lights, which are constantly on as long as i satisfy the following conditions:

1. line in set to +4
2. sound card out set to +4

if i set the soundcard and my mixer for -10, the meter reads fine, although something is not calibrated because my sonar meter shows 0db and my mixer shows about -2 to -4. so, that's something that would need to be addressed as well.

i guess i'm really trying to figure out how to get +4 performance and headroom without completely sending the mixer input in to overload. haven't been able to figure it out. unless that is something that is specifically for professional studios only because of their architecture or something.

 

[mshilarious]

it's way beyond +10. that's the highest reading on my meter before the clip lights

What mixer are you using? It sounds like your meter is calibrated to -10dBV. It also sounds like the +4 switch isn't working properly; it should pad that input 12dB. Set your soundcard at -10. What does the signal through the mixer sound like? Does it drop 12dB when you engage the +4 switch? Can you see that drop on the meter? Or maybe the PFL switch bypasses the -10/+4 switch? It shouldn't, but I'm grasping at straws here Check the meter with the PFL off and the fader set at unity.

if i set the soundcard and my mixer for -10, the meter reads fine, although something is not calibrated because my sonar meter shows 0db and my mixer shows about -2 to -4. so, that's something that would need to be addressed as well.

If your card is set to -10dBV, then 0dBFS should be 12-15 dB higher than that, or +2 to +5 on your meter.

i guess i'm really trying to figure out how to get +4 performance and headroom without completely sending the mixer input in to overload. haven't been able to figure it out. unless that is something that is specifically for professional studios only because of their architecture or something.

I think there is a misunderstanding here. +4 gear typically has more headroom than -10 gear. But with a given piece of gear, you'd have more headroom padding the input (which is what the +4 switch does) and leaving the source level low (-10). You should have identical headroom when set at -10/-10 or +4/+4, if everything is working properly.

Anyway, you shouldn't have to worry about headroom with a digital source input--it's fixed at 0dBFS max. As long as your mixer is set such that 0dBFS doesn't clip, you don't need any more headroom than that.

 

[davefromfade]

What mixer are you using?

Behringer UB1622FX-PRO

Does it drop 12dB when you engage the +4 switch?

No, when engaging the +4 switch, it applys significant gain to the signal, not reduction. The meter increases to +4 when PFL'd.

Anyway, you shouldn't have to worry about headroom with a digital source input--it's fixed at 0dBFS max. As long as your mixer is set such that 0dBFS doesn't clip, you don't need any more headroom than that.

That's true.

 

[mshilarious]

Behringer UB1622FX-PRO

No, when engaging the +4 switch, it applys significant gain to the signal, not reduction. The meter increases to +4 when PFL'd.

OK the manual says:

LEVEL
For level matching, the stereo inputs . . . have a LEVEL switch to select between +4 dBU and -10 dBV.At -10 dBV, the input is more sensitive than at +4dBu

OK, only two possibilities to reconcile this with your statement: your mixer is broken (the switch was wired in reverse); or, you are confusing the switch settings. It's hard for me to tell from a picture, but it looks like up is +4 and down is -10.

 

[davefromfade]

yes, it appears as if the switch was wired in reverse since depressing the button (-10dbv) actually adds gain to the signal. so, it is working in reverse. the way i have it set right now is the only way that it won't clip the meters on my mixer:

-10dbv out of soundcard
+4 line in from soundcard to mixer

however, the pfl meters on the mixer do not match the stereo master bus meters in sonar. if everything was calibrated properly, they should be equal (i'm assuming).

 

[mshilarious]

yes, it appears as if the switch was wired in reverse since depressing the button (-10dbv) actually adds gain to the signal. so, it is working in reverse.

No it's supposed to work that way! I don't get why proper settings are clipping though.

One thing to be aware of is that the clip light on that mixer probably comes on way too early. Given the max operating level of +22dBu, why does the clip light show at +13 dBu or so? That might make you think there's a problem with +4 when there actually isn't.

My concern with your level mismatch is that the card is probably expecting -10 inputs, and if the Behri is sending +4 outputs, then you'll have to roll off 12dB to avoid clipping, which makes your meter on your mixer useless for tracking.