My MWAF 2014 entry: Plan-Tanic

[ani_101]

Re: My MWAF 2014 entry: Plan-Tanic

Nice build and documentation.

[4thtry]

Re: My MWAF 2014 entry: Plan-Tanic

Nice build and documentation.

Thanks, Ani_101

[4thtry]

Re: My MWAF 2014 entry: Plan-Tanic

Great looking speakers. I have a pair of the RD40's that I tried to build a dipole system with and they just didn't sound good in my 10 x 12 listening room either. I blame the room because I've heard the bigger BG's and thought they were really good. I look forward to seeing the rest of the build and hearing them in Grinnell.

Ron

Thanks, Ron. Room size definitely makes a huge difference.

If you listen to the ustream archives (go to ustream/tv, then search "parts express") you can definitely hear that my speakers sounded very "thin" in the mid-bass compared to most other speakers in my category. So I'm re-working the crossover in an attempt to improve the mid-bass. Hopefully I will have them ready in time for Grinnell.


Bill

[bkeane1259]

Re: My MWAF 2014 entry: Plan-Tanic

If you listen to the ustream archives (go to ustream/tv, then search "parts express") you can definitely hear that my speakers sounded very "thin" in the mid-bass compared to most other speakers in my category.
Bill

Here's the link to the open unlimited category - you can see the other videos in the right-hand-side pane.

http://www.ustream.tv/recorded/49928865

[4thtry]

Re: My MWAF 2014 entry: Plan-Tanic

Bill really interested in the transform that you used, and think that many many many in the forums might also. Large sounding sub in a smaller box... everyone wants that!

Difvision,

Here is some info on the transform circuit. The general spec page shows my final circuit values:



I interactively adjusted these values using OmniMic & the near-field measurement
technique:



I housed my circuit in a small 5x7x1.625" plastic enclosure:



I then mounted the enclosure on a 12.5x21" board, together with a power strip,
a low voltage wall-wart power supply, and all necessary connecting cables. This made
it very easy for me to quickly connect & disconnect my speakers during the show:



The finished sub is flat to 20Hz and weighs a mere 57 pounds:

[4thtry]

Re: My MWAF 2014 entry: Plan-Tanic

And here are a few pics of the finished cabinets:

[Ron_E]

Re: My MWAF 2014 entry: Plan-Tanic

And here are a few pics of the finished cabinets:

[ATTACH=CONFIG]48904[/ATTACH] [ATTACH=CONFIG]48905[/ATTACH] [ATTACH=CONFIG]48906[/ATTACH] [ATTACH=CONFIG]48907[/ATTACH] [ATTACH=CONFIG]48908[/ATTACH]

Nice paint job. I should have to come to my place and take pictures of my projects.

Ron

[4thtry]

Re: Revised crossover for IOWA 2014

In getting ready for Iowa, I developed a "new & improved" passive xover for my RD40 towers using Bill Waslo's new Xsim program.

Here is a pic showing how I removed the original notch filter with a chisel. The original parts were simply glued in place with 100% clear silicone sealant.



Here is a pic of the modified crossover, showing the new notch filter and BSC parts. Parts are simply stacked one on top of the other and silicone sealed into place:




MY REVISION PROCEDURES:

I think that one of my big mistakes in developing the original xover came from the fact that I based all my component selections on 1 meter frequency response tests. This resulted in a speaker that sounded very thin at normal listening distances, especially in a larger room.

To develop a better xover, I decided to base my new component selections on an average power response measurement. I set up the speaker toward the center of a moderately sized room, 5.5 feet from the rear wall, 6.5 feet from the side walls, 15 feet from the back wall, and about 6.5 feet below the sloped ceiling. I removed the original crossover and placed a 100uF NPE protection capacitor in series with the RD40. I then averaged a total of 20 OmniMic readings through an 18" by 40" listening window, centered at a height of 37" and at a distance of 97" from the speaker (2.5 meters).

OmniMic settings were "track 2" sine sweep, 8ms blended, 1/48th smoothing, 100-20Khz band, advanced functions - new average (20). OmniMic has other tracks that eliminate bass, but I used "track 2" for all measurements. I placed a 100uF NPE capacitor in series with the RD40 for protection. Once the 20 measurements were taken, I used OmniMic's phase restore function to restore phase to the averaged data. For the zma data, I used an impedance curve with phase that I had measured with WT3, which essentially shows the RD40 as a 5.1 ohm resistor with a few minor bumps here and there.

Here is an Xsim screen shot of the revised crossover and new modeled frequency response:




Here is the new modeled frequency response compared to the raw averaged data without crossover (except for a 100uF NPE protection cap). The blue FR curve is the model and the red FR curve is the raw averaged data without crossover:



I revised the 5.1kHz notch filter to provide a better correction based on my revised testing method. And I added a BSC filter to bring down & flatten out the 800Hz to 10kHz band. I then added at 6.2uF cap to the BSC filter to flatten & extend the response a little from 10-20kHz.

[4thtry]

Re: Revised crossover for IOWA 2014

After I installed the new crossover on one of the speakers, I took an actual OmniMic power response measurement using the same procedures that I used to measure the raw data without crossover. Here is how the modeled response compares to the actual measured response. The modeled response is blue and the actual measured response is green:



Note that the model rolls off faster below 400Hz due to the 100uF NPE protection capacitor that was used when creating the model. This protection capacitor was not used (or needed) for the final, actual measurement. Also, the actual response shows much less of a dip in the 500-900Hz area. This may have something to due with the protection capacitor removal or it may be due to variations in microphone positions from test to test. I do not know.

Here is the frequency response of the new crossover with the microphone 1 meter from the speaker and 1 meter off the floor, again, using the same OmniMic settings:



And finally, here are the horizontal polars from 0 to 90 degrees, normalized to 0 degrees:



With these changes, the "thin" sound quality is replaced with a sound that has more "body." In the upper midrange and lower treble, there appears to be less "glare" because the notch filter is now working the way it should at both the 1 meter and 2.5 meter listening distances.

Bill

[4thtry]

Re: My MWAF 2014 entry: Plan-Tanic

Nice paint job. I should have to come to my place and take pictures of my projects.

Ron

Thanks, Ron. I was just looking at the pictures of the new venue and it looks
like the lighting may be very good for speaker photography. Lots of light flooding
in from on high through what appears to be stained glass windows. Beautiful
woodwork as the backdrop in all directions. No harsh shadows and colors seem
to be highly saturated. Should be able to get some great photos there.

Bill

[bkeane1259]

Re: My MWAF 2014 entry: Plan-Tanic

Thanks, Ron. I was just looking at the pictures of the new venue and it looks
like the lighting may be very good for speaker photography. Lots of light flooding
in from on high through what appears to be stained glass windows. Beautiful
woodwork as the backdrop in all directions. No harsh shadows and colors seem
to be highly saturated. Should be able to get some great photos there.

Bill

You're a saint, Bill.