Open Baffle help needed!

[Pioneerhip]

I want to run a single 15" Lii Audio F15 driver in an open baffle. I recently purchased the Betsy baffle with the 8" burrow driver. It is pretty great and enough that I want to go down the open baffle road, but before I start spending money or doing anything like selling my Omegas I want some advice if someone can help.

I like the Betsy baffle but wonder if, due to room size 12x11, I will always fight the balcony seat vs front row seat issue. (since the baffles are low to the floor it sounds like you are looking down at the music from a balcony vs sitting front row at a concert)

The balcony seating isn't an issue with all songs. In some songs, the music just floats like it should and just WOWs me!

I have Rythmik subs to take care of the low end so I want to run the FR wide open off of my Sayes 46 amp.

So my questions:
1. Is my room just too small for this to happen? It is a dedicated space and GIK treated
2. Would a tall baffle 40" with an FR at/ near the top with the subs be an issue
3. Would I be better off just buying the 15" Betsy baffle?
4. Any reason the Lii Audio F15 won't work?

 

[Pioneerhip]

Something like this is what I pictured:

 

[J. Frum]

Something like this is what I pictured:

This is the way.

Make them as wide and tall as you can get away with, putting the drivers’ centers at or near seated ear height. Avoid centering the drivers on the baffles on either axis.

I’m not well-versed in OB design, but would that not be the best practical advice for a 15” extended-range driver? The Big Betsy always seemed like a serious compromise between aesthetics, materials cost, and performance. Even if you favor “balcony presentation”, the home builder is better served by a jelabs open baffle.

You can make the profile narrower by using 1 or 2 “wings” a la Glow In The Dark Audio.

 

[rogerfederer]

@Poultrygeist

 

[Pioneerhip]

@Poultrygeist

I was going to tag him but didn't want to be a bother.

 

[Katalyst]

Google "the edge" software. Then you can model the baffle step for your design. Home of the Edge

 

[MWalt]

I like the Betsy baffle but wonder if, due to room size 12x11, I will always fight the balcony seat vs front row seat issue. (since the baffles are low to the floor it sounds like you are looking down at the music from a balcony vs sitting front row at a concert)

The balcony seating isn't an issue with all songs. In some songs, the music just floats like it should and just WOWs me!

I get the same thing with mine. I can't figure it out either. Mastered differently?

 

[RPMac]

+1 @Poultrygeist

The good doctor, @mhardy6647, just put up a baffle vs. frequency chart on another forum that came from JE Labs blog. I’m sure he will throw it up here as soon as he sees this. The distance from the front of the cone to the rear of the cone will determine when you will get cancellation (to some degree that I’m not sure). I’ve never used a flat board baffle…I’ve always had wings or open box backs (which is what I have now with 414Z’s).

As far as I know, there are no “full range speakers “….20-20K. There are wide range speakers that will need a degree of help on top and bottom. The challenge is to match the baffle to the wide range and integrate a sub and tweeter to blend well. This is where I run out of advice….still learning, but that’s the fun of it.

 

[Pioneerhip]

Agree on full range 20-20. I've got the low end covered and will worry about the top end down the road. I want the midrange to be more magical than the Omegas if I'm going to sell them and go Open Baffle.

 

[RPMac]

If you want the middle right, 414/32 ain’t a bad place to be.

 

[mhardy6647]

+1 @Poultrygeist

The good doctor, @mhardy6647, just put up a baffle vs. frequency chart on another forum that came from JE Labs blog. I’m sure he will throw it up here as soon as he sees this. The distance from the front of the cone to the rear of the cone will determine when you will get cancellation (to some degree that I’m not sure). I’ve never used a flat board baffle…I’ve always had wings or open box backs (which is what I have now with 414Z’s).

As far as I know, there are no “full range speakers “….20-20K. There are wide range speakers that will need a degree of help on top and bottom. The challenge is to match the baffle to the wide range and integrate a sub and tweeter to blend well. This is where I run out of advice….still learning, but that’s the fun of it.

That's about the size of it.
For the baffle size thing... I mean... @je2a3 is a member here, too.

Open Baffle

jelabsarch.blogspot.com

If nothing else, it reinforces the empirical notion that 'bigger is better' in terms of an OB if the goal is bass "extension" (for lack of a better word).
The old rule of thumb of drivers manifesting high Qts being "better" candidates for use on an OB is still a pretty good notion, too, I'd opine.

I'll quote Bill Fitzmaurice from that "other site", too:

The front and rear waves from the driver cancel each other below the frequency where the front and rear of the cone are separated by less than one-half wavelength. One-half wavelength at 40Hz is 14 feet.

source: RE: a baffle needs to be 130" in length - Bill Fitzmaurice - High Efficiency Speaker Asylum

so -- 130" half-wavelength corresponds to ca. 50 Hz

 

[Pioneerhip]

That's about the size of it.
For the baffle size thing... I mean... @je2a3 is a member here, too.

Open Baffle

jelabsarch.blogspot.com

If nothing else, it reinforces the empirical notion that 'bigger is better' in terms of an OB if the goal is bass "extension" (for lack of a better word).
The old rule of thumb of drivers manifesting high Qts being "better" candidates for use on an OB is still a pretty good notion, too, I'd opine.

I'll quote Bill Fitzmaurice from that "other site", too:

source: RE: a baffle needs to be 130" in length - Bill Fitzmaurice - High Efficiency Speaker Asylum

I read that blog today. He makes a comment about sitting 1 meter away how it might be an issue being so low. Unfortunately that's close to my situation. Closer to 2 meters but still get that balcony effect on occasion. Currently have the Betsy's on stands and that effect is gone. yes I'm aware they look silly

 

[Pioneerhip]

Pic inserted

 

[mhardy6647]

I used to have these, cut for 8 inch drivers. Something like this would likely suit you @Pioneerhip
Gave them to an old-school AK member long, long ago.

 

[Pioneerhip]

Those look around 40" high and 24" wide is that about right?

 

[RPMac]

Use two subs and set the OBs on them.

 

[btol]

Pic inserted

I think it looks kinda cool on the stand.

 

[Poultrygeist]

A wide baffle makes sense for a single full range driver. If you add bass driver support baffle width becomes less important. All of my current OB's use bass support and are bi-amped. According to Linkwitz OB bass is more accurate than box bass and I've found that to be true. It won't plumb the depths nor will it load the room but if those things are important a sub is easily added. A decent high Qts woofer should reach down to 40hz and that covers a great deal of recorded music.

I first tried the F-15 drivers in a wide baffle with dimensions similar to the big Decware and Mr Glow in the dark's version. While impressed I missed the bass that I knew could be added. Next I tried smaller baffles atop H-frames shown on the left and that made a big improvement. Would have had the same results with flat baffles but with slightly less bass output.

 

[Poultrygeist]

OB's need to be pulled out into the room as much as possible. I've often thought about adding casters to mine so they could be easily moved around and then pushed back against the wall when not in use. I like sitting close to my OB's and love listening to the Zeniths at low volume in near field especially in the early morning. Almost on the same plane with the drivers I get as much enjoyment from the back wave as from the front.

The F-15's are really good drivers and have a much bigger and more refined sound than the Betsy's so you shouldn't be disappointed. I thought at first they were slightly better than the Zenith alnico's but after putting the Zeniths back in rotation that's not the case. I no longer recommend the Zeniths to others as it's all but impossible to find a pair in good condition. My Zeniths were made in 1957 and are older than most folks on this forum.

 

[Pioneerhip]

A wide baffle makes sense for a single full range driver. If you add bass driver support baffle width becomes less important. All of my current OB's use bass support and are bi-amped. According to Linkwitz OB bass is more accurate than box bass and I've found that to be true. It won't plumb the depths nor will it load the room but if those things are important a sub is easily added. A decent high Qts woofer should reach down to 40hz and that covers a great deal of recorded music.

I first tried the F-15 drivers in a wide baffle with dimensions similar to the big Decware and Mr Glow in the dark's version. While impressed I missed the bass that I knew could be added. Next I tried smaller baffles atop H-frames shown on the left and that made a big improvement. Would have had the same results with flat baffles but with slightly less bass output.

View attachment 64404

Just so I understand:

Tall somewhat thin baffle is okay but at the expense of bass. Using the rythmik subs they can help fill the low end out.