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Author Topic: Mixer summed mono voltage?  (Read 1282 times)

Mark Wilkinson

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Mixer summed mono voltage?
« on: August 03, 2014, 05:22:25 pm »

Sorry I couldn't find this in a search....I tried, I really did :)

....but if I have a test signal @+ 4 dbu going into and coming out of each channel of a mixer's stereo input,
    what dbu or voltage should I read coming out of the mixer's summed mono output?

I'm getting about .9v from the summed mono output......which is LESS that the 1.23v I read from each channel of the stereo output. ??????

Thanks,  Mark
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Ivan Beaver

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Re: Mixer summed mono voltage?
« Reply #1 on: August 03, 2014, 08:11:48 pm »

Sorry I couldn't find this in a search....I tried, I really did :)

....but if I have a test signal @+ 4 dbu going into and coming out of each channel of a mixer's stereo input,
    what dbu or voltage should I read coming out of the mixer's summed mono output?

I'm getting about .9v from the summed mono output......which is LESS that the 1.23v I read from each channel of the stereo output. ??????

Thanks,  Mark
It depends on the particular mixer and how much gain it has in that stage.

Telling what gear you are working with goes A LONG WAY to getting answers-since gear varies quite a bit.  There is no "standard" in terms of gain.
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Tim Padrick

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Re: Mixer summed mono voltage?
« Reply #2 on: August 03, 2014, 08:59:32 pm »

1.23 from each driven one at a time, or both driven?  If the former, I'd consider that to be just fine.
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John Roberts {JR}

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Re: Mixer summed mono voltage?
« Reply #3 on: August 03, 2014, 09:20:40 pm »

What Ivan said... the summed mono output is for convenience and not critical about calibration levels. Often has it's own gain trim on the back.

JR
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Mark Wilkinson

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Re: Mixer summed mono voltage?
« Reply #4 on: August 04, 2014, 12:00:07 pm »

What Ivan said... the summed mono output is for convenience and not critical about calibration levels. Often has it's own gain trim on the back.

JR

Thanks everybody.  The mixer is an Allen and Heath Xone 464, a better DJ mixer. 

John, if the summed mono is just for convenience and isn't calibrated, I don't want to use it. I have 4 Labhorns that I want to fully power and limit properly, and I'm trying to learn the science behind proper levels, xover, limiter, and amp settings. I was going to use the summed mono as a feed to the C input on a DCX2496, because I could control the level to the subs with a separate main fader ... the mixer has two main busses, either of which can be summed to a mono out.

I've started with trying to understand signal sources and mixer levels..

Ivan, I'm not sure what you mean by 'how much gain it has at that stage'...Its maximum output level is spec'd @+26dbu.
Tim, the same signal is going to both channels via a y cable. I've been using a 1kz +4dbu 1.23v sine wave.

The mixer's input level meter reads 0db; and with the main output fader and meter at 0db, each channels output voltage is right about 1.23v ...so all makes sense so far and seems to be pretty dang accurate.
But then I read the summed mono (which doesn't have a trim) and get only about .9v. .... this is what throws me....

It's not a big deal if the summed mono is just for convenience and wont give a true level.... I can get around that easy enough.
It's more about finally learning and understanding how this stuff works, and not blowing up my labhorns  ;D

Thanks for the generousity of your help,  Mark
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John Roberts {JR}

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Re: Mixer summed mono voltage?
« Reply #5 on: August 04, 2014, 01:14:15 pm »

Thanks everybody.  The mixer is an Allen and Heath Xone 464, a better DJ mixer. 
;D
Quote
John, if the summed mono is just for convenience and isn't calibrated, I don't want to use it. I have 4 Labhorns that I want to fully power and limit properly, and I'm trying to learn the science behind proper levels, xover, limiter, and amp settings. I was going to use the summed mono as a feed to the C input on a DCX2496, because I could control the level to the subs with a separate main fader ... the mixer has two main busses, either of which can be summed to a mono out.

I've started with trying to understand signal sources and mixer levels..

Ivan, I'm not sure what you mean by 'how much gain it has at that stage'...Its maximum output level is spec'd @+26dbu.
Tim, the same signal is going to both channels via a y cable. I've been using a 1kz +4dbu 1.23v sine wave.

The mixer's input level meter reads 0db; and with the main output fader and meter at 0db, each channels output voltage is right about 1.23v ...so all makes sense so far and seems to be pretty dang accurate.
But then I read the summed mono (which doesn't have a trim) and get only about .9v. .... this is what throws me....

It's not a big deal if the summed mono is just for convenience and wont give a true level.... I can get around that easy enough.
It's more about finally learning and understanding how this stuff works, and not blowing up my labhorns  ;D

Thanks for the generousity of your help,  Mark
Did you try RTFM (read the fine manual).  According to the A/H user guide the mono output on the XLR is active balanced (both legs hot)  +4dBu, while the mono output on TRS is impedance balanced (one leg hot) -2dBu. It is pretty common to see the 6dB difference between one legged and two legged signals.

-2 dBu should be roughly 1/2 of the +4 dBu voltage or 0.61V

0.9V is too low from the mono XLR, and too high from the mono TRS.

If you are confident that your measurement is accurate contact A/H customer service for assistance

JR
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Tim McCulloch

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Re: Mixer summed mono voltage?
« Reply #6 on: August 04, 2014, 01:49:54 pm »

Thanks everybody.  The mixer is an Allen and Heath Xone 464, a better DJ mixer. 

John, if the summed mono is just for convenience and isn't calibrated, I don't want to use it. I have 4 Labhorns that I want to fully power and limit properly, and I'm trying to learn the science behind proper levels, xover, limiter, and amp settings. I was going to use the summed mono as a feed to the C input on a DCX2496, because I could control the level to the subs with a separate main fader ... the mixer has two main busses, either of which can be summed to a mono out.

Why, oh why, would you give a DJ separate control over any segment of a system?  Unless you're the only person running the rig, I think this is a bad idea and don't care how Shorty used to do it (Systems by Shorty).

That said, NOTHING about this output being different in output level will keep you from running your subs to their full potential.  You can compensate at the processor input, or output.  Makes little difference.
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Mark Wilkinson

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Re: Mixer summed mono voltage?
« Reply #7 on: August 04, 2014, 02:37:09 pm »

;DDid you try RTFM (read the fine manual).  According to the A/H user guide the mono output on the XLR is active balanced (both legs hot)  +4dBu, while the mono output on TRS is impedance balanced (one leg hot) -2dBu. It is pretty common to see the 6dB difference between one legged and two legged signals.

-2 dBu should be roughly 1/2 of the +4 dBu voltage or 0.61V

0.9V is too low from the mono XLR, and too high from the mono TRS.

If you are confident that your measurement is accurate contact A/H customer service for assistance

JR


John, I've read the manual till my eyes have crossed...even downloaded the latest revision to see if it had a better explanation of things..

I've been taking all voltages across xlr pins 2 & 3 with a good meter...
I guess I'll probably will have A/H take a look at it, if and when something major goes wrong...

Thx,  Mark
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Mark Wilkinson

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Re: Mixer summed mono voltage?
« Reply #8 on: August 04, 2014, 02:57:06 pm »

Why, oh why, would you give a DJ separate control over any segment of a system?  Unless you're the only person running the rig, I think this is a bad idea and don't care how Shorty used to do it (Systems by Shorty).

That said, NOTHING about this output being different in output level will keep you from running your subs to their full potential.  You can compensate at the processor input, or output.  Makes little difference.

Hi Tim, you called it...I'm the only operator.  This is pure personal hobby...many decades of it.
And yes, its easy enough to compensate for elsewhere.

For playing a mix of recorded music, I have found I like having two sliders next to each other, one for the mains and one for the subs.  I know this messes with the crossover region acoustically, but it sure is handy, especially for balancing out perceived  highs vs lows across wide volume swings.  Any overpowering reason not to ?

Thx, Mark
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dick rees

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Re: Mixer summed mono voltage?
« Reply #9 on: August 04, 2014, 03:26:20 pm »

Just do it (LF boost) with the channel strip EQ.
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