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May 11, 2020

If I use two inputs on an L1® does the overall level increase?

Hi

Looking for input from the engineers at Bose about the performance of a Classic/Model I or a T1® under these conditions:


  • On a Model I or Classic
  • Working with Channels 1 and 2
  • Assuming that all settings (trim, R1 settings, Presets) are the same for both Channels

Questions
  1. If I run the same input source to both Channels 1 and 2, will the L1® system output sound pressure level be the same as if I run the source to only one Channel.

  2. Would the answer be the same if I run two identical signals to two T1® Channels (with identical settings) and run the T1® output to a Model II?

  3. Does any of the above change if the inputs are Left and Right outputs from a stereo source (into two input channels on a Model I/Classic or T1®?)

  4. A question about psycho-acoustics: If the sound pressure level is higher in any of the above scenerios, is a listener likely to perceive the difference in volume? If so, would the perception of difference be
    - quantitative (e.g. "that sounds louder") or
    - qualitative (e.g. "that sounds better") or
    - both
    - neither (if something else - please say something about that).


Thank you.

ST




related thread: channels and "fuller" sound
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Re: If I use two inputs on an L1® does the overall level increase?

Hi ST!
It's been a while since I have posted, nice to join again.

1. Yes, if you put the same signal into two channels and sum them, the output will be twice as high as if you just had one. The output SPL will generally be 6 dB higher (exception below)
2. Yes, same for T1
3. If stereo, the result will be up to 6 dB higher, depending on the stereo mix. To demonstrate by the extreme examples, if the left and right channels were the same (a mono mix), you would get 6 dB. If they were completely different, like flute in one channel and bass in another, you might not perceive much SPL increase.

For most typical mixes it will be somewhat louder, 3 to 6 dB. And, of course, you have the advantage of hearing all the stereo material which you would miss if you only used one of the stereo source channels.

4. Perception: When we are asked to do an "A/B test" between two sources, people tend to think that louder is better. If one is slightly louder, most people will rate it as slightly better in quality.

So in the cases you list, people will hear louder, and maybe better (unless it gets too loud and is annoying)

The exception I'd like to mention is that this applies only if you have enough headroom in the L1 to play 6 dB louder. If you are near limiting and you add the second signal (which is the same as turning up the volume control 6 dB), you would just limit. Then it would sound not much louder, and somewhat worse if you hear the effects of the limiter.

Another way to say that is that using two channels will not increase the maximum volume your system can obtain.

I hope that helps!

-bill
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Re: If I use two inputs on an L1® does the overall level increase?

Thanks Bill
more later

from the dentists chair
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Sep 26, 2007

Re: If I use two inputs on an L1® does the overall level increase?

Hey guys, after reading this post, I have additional questions. 1) M1, using a mic for input, can I use the XLR out of channel 1 and put it into channel 2 without causing a problem since I think the XLR out is pre amplifier. 2)Using the same presets on both channels would this more or less have a resulting boost of fullness on the mic maybe similar to a compressor? along with an increased volume?
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Re: If I use two inputs on an L1® does the overall level increase?

Hi larry-b,

I expect that this would be a little louder, but I doubt that it would convey any benefit that you couldn't get more simply just by turning up the volume on the R1 Remote.

You may run into an issue with the output of the Channel 1 XLR line-out being too hot (level too high) for the Channel 2 XLR input. If it is, then you will have distortion.
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Sep 26, 2007

Re: If I use two inputs on an L1® does the overall level increase?

Thanks ST, the reason I asked is that playing very small rooms at lower main volume the vocals seem to lose their punch. When I turn the main volume below 10 o'clock is when the vocals become muddy. The instruments seem to lose very little. When the main controller volume is above 10 o'clock there is no problem. I recently played a couple very small rooms and had to keep the volume below 10 o'clock and the vocals lacked in quality to my ear. I was thinking maybe by using two channels for the vocal I could overcome this.
Thanks for the input
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Sep 26, 2007

Re: If I use two inputs on an L1® does the overall level increase?

ST, you were correct, the signal from chan 1 out is too hot and causes distortion however with the main volume down at 9 o'clock and jumping from channel 1 to chan 2 the vocals sounded great at lower main volume before distortion. I think I will try a "Y" connector from the mic.
Thanks
Larry B
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May 25, 2004

Re: If I use two inputs on an L1® does the overall level increase?

Hi larry-b

How the eq is set can affect the sound at different volume levels. In my experience if Lows and highs are bumped up a bit and the trim and volume are set for the bump in a louder venue, turning the volume down might require a new eq and trim calibration for the softer volume level.

If one channel is muddy, for whatever reason, you wouldn't want to double the mud by running the same signal through another channel.

O..
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Re: If I use two inputs on an L1® does the overall level increase?

Hi larry-b,

quote:
Originally posted by larry-b:
ST, you were correct, the signal from chan 1 out is too hot and causes distortion however with the main volume down at 9 o'clock and jumping from channel 1 to chan 2 the vocals sounded great at lower main volume before distortion. I think I will try a "Y" connector from the mic.
Thanks
Larry B


If you've got the "Y" connector, it probably won't hurt to try it. But I wouldn't go out and buy one. The reason - splitting the signal like this will reduce the output at the output ends of the "Y". In other words you can't get something out of nothing. So you split the signal and end up with two lower signals.

If you try it, please let us know it works.

PS
I just saw Oldghm's post above. Good thoughts. Have you tried adjusting the tone controls when you are running at lower volume?
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Re: If I use two inputs on an L1® does the overall level increase?

Oldghm / ST
Thanks for the input. I understand about 2 muddy signals. I tried bumping the EQ settings and it helped considerably, I may be able to work with it this way. I have the parts to make a "Y" cable and may try that later.
Thanks
Larry B