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Early in the Movie "The Matrix" Neo is given a choice of the red pill or the blue pill. As such I have a simpler design using the Dayton RS150 and BG Neo3PDR, which has been around since about 2006 and a more involved design using the Neo3PDR, Neo8, and dual RS150T's that was developed in 2009.
The red pill will allow one to see just how far the rabbit hole goes, so that title must be given to the TMWW version that uses a BG Neo3PDR tweeter, BG Neo8 (non-PDR) midrange, and dual Dayton RS150T woofers.
The Matrix is so named because the BG Planar drivers with their orderly series of openings and rectangular shape always reminded me of a matrix. Also, I've always been impressed with the way planar drivers deal with dense complex passages. When I think of the movie "The Matrix" the scene that stands out is when Neo and Trinity enter the office building armed with just about every automatic weapon imaginable and proceed to shoot everything in sight - just the kind of scene these drivers where made to reproduce.
This design is a tall slender floor stander - 43.5" tall by only 7" wide and 14.5" deep. The form factor, coupled with the matte black finish is intended to blend well on either side of a big flat panel TV. The cabinet size and driver positioning allows the Neo8 to be mounted at a height to align with a typical seated position, which is important given its limited vertical dispersion.
Before designing these, I did some homework. A couple of Neo3/Neo8 designs had been attempted. Javier Huerta had documented a design called the Minilith on the HTGuide forum that used an 8" Seas woofer and LouC had attempted an open baffle mid tweeter design with an RS-225 woofer. I was relatively impressed with how Javier's design came out, but had a completely different form factor in mind and had a pair of RS-150T's in hand that I won as a door prize courtesy of PE at DIY Iowa 2008.
Based on some of Javier's findings, I decided to keep the range of operation of the Neo8 relatively limited at 1 to 3.5 kHz, but to use shallow slopes to mitigate any issues with differing off axis behavior between the drivers. I also decided to pair up the RS-150T's to give a little more power handling and air-moving capability to support the extension in the 30's they can provide in a larger enclosure.
I ran a few sims and completed cabinet construction with the help of my brother just in time for DIY Iowa 2009. I received a lot of favorable feedback, particularly regarding the midrange performance of the Neo8. A couple of people thought the Neo3PDR was voiced a little hot, but the greatest criticism had to do with the RS150T's trying to make deep bass in the Grinnell auditorium.
After the show, I brought the crossovers back out of the cabinets and made some changes and also worked on the cabinet alignment. For the cabinets, I decided to extend the port length (3" diameter PVC) from 4" to 6.5" to create an extended bass shelf alignment. I also added heavy polyfill to the bottom quarter of the cabinet to make sure that any pipe resonances due to the tall, slender enclosure were fully dealt with. These changes greatly improved bass quality and control.
For the crossover, my sims did not accurately represent the effect of the rear chamber, which was formed by a rectangular clearance hole for the Neo 8 extended through two layers of 3/4" mdf and lightly stuffed with polyfill. The impact, as I found out when I finally measured these, was a slight response peak around 800 Hz, a downward slope through the midrange with a dip of about 2-3 dB centered around the mid-tweeter crossover point of 3.5 kHz.
The final crossover achieves a very flat, balanced on-axis response through the midrange and treble up to about 16 kHz with a sharp dropoff above that. The reason for that is a small series inductor in series with the Neo3PDR. The series inductor reshapes the Neo3PDR's response to help alleviate the lack of energy between the two peaks at 3.5 kHz and 12 kHz. I think the approach worked very well in making the Neo3PDR sound better balanced throughout its range.
Overall, I am very happy with how this project has turned out. The BG drivers have increased a lot in price since I started, but these offer some of the best resolution without harshness that I've heard from the midbass region through the treble. The bass is articulate and is quite satisfying in most small to medium rooms. In a large room or HT, one would likely want to supplement these with a sub. The attachments should give a good starting point to anyone who might want to give these a try.
The red pill will allow one to see just how far the rabbit hole goes, so that title must be given to the TMWW version that uses a BG Neo3PDR tweeter, BG Neo8 (non-PDR) midrange, and dual Dayton RS150T woofers.
The Matrix is so named because the BG Planar drivers with their orderly series of openings and rectangular shape always reminded me of a matrix. Also, I've always been impressed with the way planar drivers deal with dense complex passages. When I think of the movie "The Matrix" the scene that stands out is when Neo and Trinity enter the office building armed with just about every automatic weapon imaginable and proceed to shoot everything in sight - just the kind of scene these drivers where made to reproduce.
This design is a tall slender floor stander - 43.5" tall by only 7" wide and 14.5" deep. The form factor, coupled with the matte black finish is intended to blend well on either side of a big flat panel TV. The cabinet size and driver positioning allows the Neo8 to be mounted at a height to align with a typical seated position, which is important given its limited vertical dispersion.
Before designing these, I did some homework. A couple of Neo3/Neo8 designs had been attempted. Javier Huerta had documented a design called the Minilith on the HTGuide forum that used an 8" Seas woofer and LouC had attempted an open baffle mid tweeter design with an RS-225 woofer. I was relatively impressed with how Javier's design came out, but had a completely different form factor in mind and had a pair of RS-150T's in hand that I won as a door prize courtesy of PE at DIY Iowa 2008.
Based on some of Javier's findings, I decided to keep the range of operation of the Neo8 relatively limited at 1 to 3.5 kHz, but to use shallow slopes to mitigate any issues with differing off axis behavior between the drivers. I also decided to pair up the RS-150T's to give a little more power handling and air-moving capability to support the extension in the 30's they can provide in a larger enclosure.
I ran a few sims and completed cabinet construction with the help of my brother just in time for DIY Iowa 2009. I received a lot of favorable feedback, particularly regarding the midrange performance of the Neo8. A couple of people thought the Neo3PDR was voiced a little hot, but the greatest criticism had to do with the RS150T's trying to make deep bass in the Grinnell auditorium.
After the show, I brought the crossovers back out of the cabinets and made some changes and also worked on the cabinet alignment. For the cabinets, I decided to extend the port length (3" diameter PVC) from 4" to 6.5" to create an extended bass shelf alignment. I also added heavy polyfill to the bottom quarter of the cabinet to make sure that any pipe resonances due to the tall, slender enclosure were fully dealt with. These changes greatly improved bass quality and control.
For the crossover, my sims did not accurately represent the effect of the rear chamber, which was formed by a rectangular clearance hole for the Neo 8 extended through two layers of 3/4" mdf and lightly stuffed with polyfill. The impact, as I found out when I finally measured these, was a slight response peak around 800 Hz, a downward slope through the midrange with a dip of about 2-3 dB centered around the mid-tweeter crossover point of 3.5 kHz.
The final crossover achieves a very flat, balanced on-axis response through the midrange and treble up to about 16 kHz with a sharp dropoff above that. The reason for that is a small series inductor in series with the Neo3PDR. The series inductor reshapes the Neo3PDR's response to help alleviate the lack of energy between the two peaks at 3.5 kHz and 12 kHz. I think the approach worked very well in making the Neo3PDR sound better balanced throughout its range.
Overall, I am very happy with how this project has turned out. The BG drivers have increased a lot in price since I started, but these offer some of the best resolution without harshness that I've heard from the midbass region through the treble. The bass is articulate and is quite satisfying in most small to medium rooms. In a large room or HT, one would likely want to supplement these with a sub. The attachments should give a good starting point to anyone who might want to give these a try.
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