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In the Forum: Horn-Loaded Speakers
In the Thread: Midbass impedance bumps -- why and what to do?
Post Subject: Midbass impedance bumps -- why and what to do?Posted by noviygera on: 10/21/2010
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I though this would be answered elsewhere (AA) but Bruce Edgar did not reply. This question is important for me, maybe someone can help.

When running an impedance sweep on the Edgar 80Hz horn some serious bumps showed up. (I ran the sweep because it sounded wrong so I decided to investigate)
Also, I have to run a high pass at 160Hz with 6db slope to even out the mid bass!!!

Now the problem that I have with sound is:
1. too boomy and tubby, just plain muddy sounding when simply crossed over at 80 and 350hz
2. box panels, horn flare, rear chamber all resonate. The freq are about 190, 210 hz, and its noticeable by placing hand on different parts of speaker. I wish she was a hot girl, but it's only an audio speaker.

What to do? Here are two imp. sweeps, and maybe something can be deduced.

1st imp. sweep. -- no changes to horn.

Edgar 80Hz horn_factory_imp_sweep.JPG

2nd impedance sweep below. Here I added some wood blocks to the REAR CHAMBER. Notice the Fs went up by 10hz. Curve looks a little smoother.

Edgar 80Hz horn_small_back_chamb_imp_sweep.JPG



Now my question is:

What do I learn from this experiment?
Should the rear chamber be made even smaller? Than Fs will go up more.
But should my goal be to even out the curve at the expense of low Fs?

I do not mind to have a higher Fs for this horn, by the way.

Thank you,
Herman

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