[NavyDoc]

I am in the contemplation stage of my next project.  I am certain that it will be an open baffle design and will use the SW-12-16FR drivers for bass.  I know that they work very well in the W- and H-frame designs shown on the GR Research website. Has anyone have experience in using them in an U-frame?  I see that AE has a U-frame design for their dipole drivers, and I prefer the U-frame for aesthetics (two forward facing drivers).  I understand that it is a compromise in force cancellation, but if the aesthetics is preferable to me.

Thanks!

[Danny Richie]

I am in the contemplation stage of my next project.  I am certain that it will be an open baffle design and will use the SW-12-16FR drivers for bass.  I know that they work very well in the W- and H-frame designs shown on the GR Research website. Has anyone have experience in using them in an U-frame?  I see that AE has a U-frame design for their dipole drivers, and I prefer the U-frame for aesthetics (two forward facing drivers).  I understand that it is a compromise in force cancellation, but if the aesthetics is preferable to me.

Thanks!

There is no forced cancellation effect either way.

The U frame makes one long port instead of two shorter ones. So you can't play the U frame up as high. So instead of being able to cross them up into the 200 to 300hz range in the H frame, the U frame will be about half of that.

And the U frame put a LOT of force on the side panels. They have to be really well braced and the side panels have to be a lot thicker.

You can use the H frame and face them the same way.

[NavyDoc]

There is no forced cancellation effect either way.

The U frame makes one long port instead of two shorter ones. So you can't play the U frame up as high. So instead of being able to cross them up into the 200 to 300hz range in the H frame, the U frame will be about half of that.

And the U frame put a LOT of force on the side panels. They have to be really well braced and the side panels have to be a lot thicker.

You can use the H frame and face them the same way.

Thanks Danny, looks like the H-Frame is superior for my application. Planning to use for the low end partnered with an 8 inch full range driver (Voxativ, AER, Cube Audio, etc.).  The ability to run up to 300 Hz is important as I want to keep the baffle to 16 inches.

Plan to start with a less expensive driver at first (Wild Burro Audio Labs, MarkAudio, Tang Band, etc.).

[Danny Richie]

Just be sure to minimize the baffle size around those full range drivers. The enemy to a transparent sound with good imaging and layering is a wide baffle. The bigger the baffle the more it will sound like it is playing from the baffle forward. So keep it small.

So you will then need to add just the right amount of side wing to separate the front and back waves and create a flat response roll off in the lower end.

[NavyDoc]

Thanks for the advice.  After searching this forum all afternoon I stumbled across mlundy57's OB Wedge Base for dual r12 in drivers (http://www.audiocircle.com/index.php?topic=138533.0).  If i made the front baffle 9 inches and scaled Mike's design to fit.

Hmmm.....

[mlundy57]

Thanks for the advice.  After searching this forum all afternoon I stumbled across mlundy57's OB Wedge Base for dual r12 in drivers (http://www.audiocircle.com/index.php?topic=138533.0).  If i made the front baffle 9 inches and scaled Mike's design to fit.

Hmmm.....

That’s actually Danny’s design for three 8” drivers to match the narrow profile of the Wedgies. I scaled it to work with two 12” drivers. If I did it again I would make the front 2” wider to have more room for the drivers inside the cabinet

[NavyDoc]

That’s actually Danny’s design for three 8” drivers to match the narrow profile of the Wedgies. I scaled it to work with two 12” drivers. If I did it again I would make the front 2” wider to have more room for the drivers inside the cabinet

If I add the two inches that would be 10 inches if I read your thread correctly. That would be near perfect.  Only issue I see is what would be the highest crossover point for the bass.  I know that 8 inch full range drivers are hard pressed to go lower than 200 Hz (if that) on narrow baffles

But, this really looks to have potential.

Thanks for the information.

Steve

[mlundy57]

If I add the two inches that would be 10 inches if I read your thread correctly. That would be near perfect.  Only issue I see is what would be the highest crossover point for the bass.  I know that 8 inch full range drivers are hard pressed to go lower than 200 Hz (if that) on narrow baffles

But, this really looks to have potential.

Thanks for the information.

Steve

Steve,

My wedge shaped bass cabinets are 6" wide in the front and 12" wide in the rear (the sides go back at a 100 degree angle). I used them with Wedgies which cross over at 200Hz.  Making the front 8-10" wide would make the rear opening somewhere around 16-20". I don't know what affect this would have on output and crossover point.

Mike

[Danny Richie]

If I add the two inches that would be 10 inches if I read your thread correctly. That would be near perfect.  Only issue I see is what would be the highest crossover point for the bass.  I know that 8 inch full range drivers are hard pressed to go lower than 200 Hz (if that) on narrow baffles

But, this really looks to have potential.

Thanks for the information.

Steve

Keep the front area small and shape the response with the side wings.

I'll post some measurements to show some examples.

[Danny Richie]

Okay, here is a good example for you. I'm giving the farm away on this one. I designed the baffle and side wings for this speaker for Hawthorne Acoustics, and the crossover too.



It is hard to see in the picture but there is a short wing and a long wing on each side angled out 100 degrees from the surface of the front baffle.

All of these measurements show the response of the 8" woofer before any crossover is added.

The grey line in the background is the response of the 8" woofer with no side wings. It is shown for reference with all of the measurements. The green line is with a 10" wing added to one side only.



A 10" long wing and a 2" short wing.



A 10" long wing and a 4" short wing.



A 12" long wing only.



A 12" long wing and a 2" short wing.



A 12" long wing and a 4" short wing.



A 14" long wing only.



A 14" long wing and a 2" short wing.



A 14" long wing and a 4" short wing.



These were the best two. A 12" long wing with a 2" short wing and the 14" long wing with 2" side wing.



Get it?

[Jonathon Janusz]

Danny, I've seen you talk about this before, but I think this might be the first time I've seen you walk through the process with graphs.  I'm presuming the measurement graphs posted are on-axis measurements of the woofer?  Something I've kind of wondered about using this technique to shape the frequency response is how does this technique change what happens off axis?  I'm assuming that one would mostly see variation in the horizontal based on the two different side wings being full length of the baffle, as in all cases vertically the baffle stays the same?

[NavyDoc]

Okay, here is a good example for you. I'm giving the farm away on this one. I designed the baffle and side wings for this speaker for Hawthorne Acoustics, and the crossover too.



It is hard to see in the picture but there is a short wing and a long wing on each side angled out 100 degrees from the surface of the front baffle.

All of these measurements show the response of the 8" woofer before any crossover is added.

The grey line in the background is the response of the 8" woofer with no side wings. It is shown for reference with all of the measurements. The green line is with a 10" wing added to one side only.



A 10" long wing and a 2" short wing.



A 10" long wing and a 4" short wing.



A 12" long wing only.



A 12" long wing and a 2" short wing.



A 12" long wing and a 4" short wing.



A 14" long wing only.



A 14" long wing and a 2" short wing.



A 14" long wing and a 4" short wing.



These were the best two. A 12" long wing with a 2" short wing and the 14" long wing with 2" side wing.



Get it?

Very nice demonstration on the effect of wing size! I have been modeling using Basta but clearly real data trumps simulations.

Are cardboard wings suitable for making measurenents?

[HAL]

captainhemo's modular sub H-Frames can also be used as all forward firing drivers.  Just let him know if you want them that way.

Great info from Danny. 

[NavyDoc]

captainhemo's modular sub H-Frames can also be used as all forward firing drivers.  Just let him know if you want them that way.

Great info from Danny.

Those flatpacks look really great, but I like to suffer needless pain so will likely build my own.  I need to get to your place to hear what these systems can do.  My current speakers are 28" wide Three-Ways that are great for home theater but I am looking for the ultimate resolution and imaging for a separate music only system.  Danny sure has some fantastic designs. The NX-Otica MTM looks nice, but right now I am enamored with the concept of a single driver running from 200 Hz to 15 kHz (I can't hear above that, to much weapons training and a close up experience with heavy  ordnance).

[Danny Richie]

Danny, I've seen you talk about this before, but I think this might be the first time I've seen you walk through the process with graphs.  I'm presuming the measurement graphs posted are on-axis measurements of the woofer?  Something I've kind of wondered about using this technique to shape the frequency response is how does this technique change what happens off axis?  I'm assuming that one would mostly see variation in the horizontal based on the two different side wings being full length of the baffle, as in all cases vertically the baffle stays the same?

There is very little difference in one direction verses the other.

[Danny Richie]

Very nice demonstration on the effect of wing size! I have been modeling using Basta but clearly real data trumps simulations.

Are cardboard wings suitable for making measurenents?

Yes, cardboard is fine. I also use 3/4" Styrofoam. Not the type that is compressed beads. I used the type that is a solid piece.

And simulations are nothing compared to real measurements.

[Danny Richie]

Those flatpacks look really great, but I like to suffer needless pain so will likely build my own.  I need to get to your place to hear what these systems can do.  My current speakers are 28" wide Three-Ways that are great for home theater but I am looking for the ultimate resolution and imaging for a separate music only system.  Danny sure has some fantastic designs. The NX-Otica MTM looks nice, but right now I am enamored with the concept of a single driver running from 200 Hz to 15 kHz (I can't hear above that, to much weapons training and a close up experience with heavy  ordnance).

I know everybody tries to run those big baffles for open baffle applications, but they really eat up the real performance.

Full range drivers are fun and I have some of the best sounding little 3" full range drivers out there. And I use them is a couple of designs where one unit covers from about 250Hz and up. See the Flat 5 and Skinny 6's.

But the NX-Otica and NX-Treme's are on a completely different level. 

[NavyDoc]

I know everybody tries to run those big baffles for open baffle applications, but they really eat up the real performance.

Full range drivers are fun and I have some of the best sounding little 3" full range drivers out there. And I use them is a couple of designs where one unit covers from about 250Hz and up. See the Flat 5 and Skinny 6's.

But the NX-Otica and NX-Treme's are on a completely different level.

My big baffles are not open baffle, they are a 18" LF driver with horn midrange (10" driver) and horn HF (1.5" throat).  I use a dbx Venu360 for XO and DSP, they measure really well and sound great for their intended purpose (home theater).



The MTM NX-Otica paired with the dual 12 H-frame subs seems like a cool approach.  Where can I find dimensional drawings of the NX-Otica?

[Danny Richie]

My big baffles are not open baffle, they are a 18" LF driver with horn midrange (10" driver) and horn HF (1.5" throat).  I use a dbx Venu360 for XO and DSP, they measure really well and sound great for their intended purpose (home theater).



The MTM NX-Otica paired with the dual 12 H-frame subs seems like a cool approach.  Where can I find dimensional drawings of the NX-Otica?

The kit comes with a flat pack. The front baffle is 52" tall.

[Scott Joplin]

And simulations are nothing compared to real measurements.

Do you have measurements of the off axis response to share?