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Ballancing output


Dave A

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Never done it but would determine the frequency both drivers have the same crossover -[whatever]dB (easier to determine if symmetrical slopes?), generate that frequency only, and set the gain on the HF to output the same volume each individually as my starting point, if using only an SPL-measuring device.  As my starting point...

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Yesterday I tried the balancing so all four drivers were the same and it did not sound good at all. Went back to the 2.5db plus on the 402's and the magic was back. As an aside here I had an LSI buyer over the other day and I never let people hear the big boy until they decide to buy or not buy what they came here for. They always do buy in case you were wondering. I mentioned that the same K-43 woofer in his LSI's were the same exact ones in my S-MWM bass bins. The amazing difference that size and distance makes in a single fold horn has to be heard to be believed.  I lack the engineering back ground to say why the 402's need to be run at a higher db than the bass bins but my ears tell me this is true.

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16 minutes ago, Panelhead said:

  The bass bins laying on the concrete floor really couples the wave launch to boost the bin output. If you stood them up, it might be better flat.

He's already measuring the coupling that takes effect correct?  The way I read it, he's going 2dB hot in overall output on the tops when compared to the bottoms including boundary gain.

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I measure each unit and hold the mike by hand in appx the same place relative to the other one. I mute the set not being measured and then put the mike right in the mouth of the horn flush with the front edge and centered in the cavity.

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11 minutes ago, Dave A said:

I measure each unit and hold the mike by hand in appx the same place relative to the other one. I mute the set not being measured and then put the mike right in the mouth of the horn flush with the front edge and centered in the cavity.

What?  Your bass bin has 2 mouths correct?

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3 minutes ago, Dave A said:

Why yes they do but I only measure one, the center of the opening on the same side of each bin. And then the center of the 402's.

There's your answer then.  You're not accounting for the output provided by the other horn on the bass bin.  That's why you need the 402 hotter.

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44 minutes ago, Panelhead said:

Plus you really need to measure out in the room.

Uhhh...I wouldn't do that.  The only time to move the microphone away from 1m distance (in-room) is when trying to dial in a subwoofer, and even then you're probably going to get better results if you leave the microphone distance at 1 m and live with the pressure zone/nearfield issues.

 

The critical distance of the room (a not-damped room) at the crossover frequency with the K-402 and MWM-type bin (high directivity index for both of these horns at ~400-500 Hz) is probably on the order of 2-3 m, so you're going to be measuring diffuse reflections in-room if you try to measure farther away than 1m using something like continuous pink noise.  The only way to measure farther back and avoid overwhelming reflections in-room is to use upsweeps ("chirps")--like the room correction software applications use.

 

Chris

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18 minutes ago, rplace said:

I don't think I'd put much faith at all into something hand held.

 

It'd be alright for a quick spot-check or similar use.  Definitely not for any part of a comprehensive, iterative process except the very initial stages, perhaps.

 

Although I'm sure there are as many people with perfect muscle memory as there are with perfect aural memory...

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