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Correction network for JE Labs baffles

69.23.44.84

I was just wondering if anybody has experience building a simple network to tame the baffle hump of this baffle.

It's the only thing about them that bothers me at all.

Searches did not turn up anything.

Follow Ups:

Reply + Radio Shack SPL Meter Follow-Up - Gerry E. 08:21:42 06/30/09 (3)
Hey Paul:

Can you be more specific on what you are actually hearing that you don't like?

Here's a follow-up on my post about the RS SPL meter (digital version) and Rives Audio Test CD #2. I used the pre-equalized test tone signals even though they were specifically designed for the RS analog meter.

Before I go any further I know that there are many caveats/qualifiers to this test procedure. I will just lump these all together and say that all of the following is FWIW . My measurements were taken at the listening position using 80db at 1000hz as the reference level (as per the test instructions).

I was able to tweak the system to get the results shown in the frequency response chart shown above. I was not able to do too much tweaking in the woofer/mid-range crossover range (approx. 3000 - 5000hz) except for some minor baffle placement adjustments. As can be seen in the chart above, it's actually pretty good. It wasn't necessary, but I could have changed the cap value on my tweeters.

The area that I was able to apply some effective tweaking was in the sub-woofer/woofer integration (approx. 20 - 100hz). To get flatter response, I needed to increase the sub-woofer crossover frequency, but lower the sub-woofer output level. The overall sound is quite a bit smoother than my original sub-woofer set-up. For that reason alone, I feel that this was a very worthwhile exercise.

You will notice that there are some drop-outs at 50, 80 and 500hz. I assume that these are room nodes. Here's an oddity and maybe it's just a coincidence - I have a live-room frequency response graph from Western Electric for their model 728B speaker. It shows similar drop-outs at approx. 60, 80 and 450hz. Obviously my room is different than theirs and my 754A speakers are not exactly the same as the 728B, but I thought it was interesting.

Gerry
- RE: Reply + Radio Shack SPL Meter Follow-Up - Paul Folbrecht 09:49:30 07/05/09 (0)
  Hi Gerry,
  
  Subjectively, the problem I wanted to correct was an overly prominent midbass. The bass is just a bit muddy - better with the baffles elevated 8" rather than on the floor, but still muddy - and I mean more muddy than any reasonable bass-reflex box.
  
  Putting the meter to the speaker did show some unevenness to the bass, but also, and this was somewhat surprising to me, a 3-4 dB shelf at 1.3-3 Khz or so. This, of course, is likely due more to the driver than the baffle.
  
  As Ron pointed out, the correction network for baffle step is a broad attenuation above the step. But I'm sure what's going on here is more complex than that.
  
  However, *they sound good*! They still sound extremely good as-is. So the priority is low.
- What Radio Shack SPL Meter??? - Ivan303 10:16:12 06/30/09 (1)
  Did you have to create the graph yourself?
  
  Boats and Fish!
  - RE: What Radio Shack SPL Meter??? - Gerry E. 11:32:57 06/30/09 (0)
    Google "Radio Shack SPL Meter" and it should be the first link on top.
    As for the chart, of course I had to fill it in based on the test tone measurements. However, anyone can download the blank chart and print it out. Use the link below and select the "Frequency Chart - Color" link in the Downloads section.
    Gerry
    - Rives Audio (Open in New Window)
    Edits: 06/30/09
RE: Correction network for JE Labs baffles - Ron Oehlert 09:12:59 06/28/09 (3)
Rather than limit web searches specifically to JE Labs example, search instead for baffle step correction in general, then you can DIY your own simple design via width of baffle.

Edits: 06/28/09
- RE: Correction network for JE Labs baffles - Paul Folbrecht 10:17:39 06/28/09 (2)
  Yeah, that's where I was headed - just figured I'd check for a ready-made soln first.
  
  Really it's just a notch filter..
  
  My complication is I lift the baffles which means the baffle hump is not where the theory would predict...
  - Nit picking - Ron Oehlert 18:11:34 06/28/09 (1)
    Floor bounce augmentation (in-room placement) is a different issue than width-of-baffle attenuation; unless placed against the rear wall, width of baffle attenuation remains regardless of stands. And rather than a narrow notch filter, ALL frequencies above the step are attenuated such that the lower frequencies seem boosted by comparison (amplifier Tone controls have the same effect).
    - RE: Nit picking - Paul Folbrecht 18:31:55 06/28/09 (0)
      Ron,
      
      Those are far from nits!
      
      Hopefully I would have realized both facts before building anything - thanks.
RE: Correction network for JE Labs baffles - freddyi 08:03:45 06/26/09 (0)
did you ask over at Audio Circle's open baffle forum and DIY Audio?

with a somewhat smaller baffle oriented vertically the Silver Iris with Q ~1.1 worked down to its resonance

I put a lower Q P-Audio 15 on the same baffle and that had enough bass for my tastes - EQ/correction would be needed for some speakers

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