# Open Baffle Mid Range



## Spadez (Oct 14, 2009)

Hi,

Ive been on a bit of a learning curve and I think I have found the solution to my space issue for the mid ranges that will sit on my desk and that is to use an open baffle setup for my midranges and tweeter with a crossover cricuit mounted externaly.

Ive been trying to find as much information on these kind of setups, but I have some questions outstanding that I would appreciate help on.

1. Are these open baffle systems capable of going into the 90Hz-100Hz range?
2. Does the size of the speaker mount plate have a large effect on performance
3. Is an open baffle setup capable of producing great sound, any major disadvantages?
4. Can this literally be a speaker mounted in a bit of wood, or is it more complicated than that (requires side panels, requires a small block at the bottom etc)?
5. How do I determin the size of the open baffle setup? 

If anyone is able to help me with this it would be much appreciated.


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## Yad (Oct 19, 2009)

Open baffle. You may also call it "dipole", because driver radiates in to both sides with 180 degrees of phase difference (between front & rear sides). That's why it is also a problem. Lowest frequencies are canceling out. The lowest freq. that you can reach - is nearly F=340/d (F-freq. 340 (meters per second) - sound speed in air, d - is a 1/4 of the distance (in meters) between the middle of driver & edge of the baffle) or 1/2 of the baffle's width. So, for your 100 Hz at -6 db point you will need approx 3.4 x3.4 meters baffle. 
Furthermore, your driver in the open enclosure will not work properly at the lo end ('cause of it's Thiele-Small parameters) 

the "+" of this enclosure are: 1) symmetrical acoustical load to the diffusor 2) more natural sound (if you make baffle correctly) 

notes: baffle should not have a true square shape. better is asymmetrical. Not every driver is made for O B enclosure


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## Yad (Oct 19, 2009)

NB! midrange (higher than 200-250) - is not bidbass (lower than 200-250 Hz) response.


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## Yad (Oct 19, 2009)

calculations:
http://www.hometheatershack.com/for...mid-high-speakers-match-sub-3.html#post198532


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## JCD (Apr 20, 2006)

Spadez said:


> Hi,
> 
> Ive been on a bit of a learning curve and I think I have found the solution to my space issue for the mid ranges that will sit on my desk and that is to use an open baffle setup for my midranges and tweeter with a crossover cricuit mounted externaly.
> 
> ...


1. Not easily. My understanding is that there is a LOT of EQing being done on the Orion speakers to get them down low. They also have that "cavity" to help boost of the low end.
2. Some. I think Yad was showing how the size of the baffle helps or doesn't help reinforce the low end. Basically, the lower the frequency, the bigger the wave length, the wider the baffle needs to be in order to go stay in 2pi space vs 4pi space. 
3. Yes. The Orion speakers are supposed to sound awesome when set up properly. One major disadvantage is that they need a lot of space around them. I think you can find out the details here.
4. It's more complicated if you want to do it right. The link in 3. gives a lot of good info.
5. It depends. Again, I think the link in 3. may help.


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## Yad (Oct 19, 2009)

it could be interesting for you 
On the graphs you can see deep EQ at the lo end (those >20 Db's which i told you @ LF ) and 8 Db's at midwoofer Seas W22EX001 this is very big one.


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## Yad (Oct 19, 2009)

These are the specifications:
Open baffle cabinet 
Outside dimensions: Height 46.25" - Width 13" 
Depth 2" at top, 12" at base, 16" at 14" up
Weight 60 lb (27 kg)
3-way active speaker system
Crossovers at 120 Hz and 1440 Hz, both LR4 (24 dB/oct)
Crossover/Equalizer using two ORION ASP printed circuit boards
Tweeter - Seas T25CF002 - No, not a ribbon - 
42" up, no 2.8 kHz notch filter as in PHOENIX
Preferably no grill to cover the tweeter
Midrange - Seas W22EX001 - No, not a smaller diameter - 
Front mounted to baffle, no spine, but see Revision 0.1
34.5" up, 5 kHz notch filter
Woofer - two Peerless 10" XLS, 830452 
Push-pull mounted in H-frame of 11.5" x 11.5" x 24.5" OD
Each driver with its own >60 W amplifier
Response -3 dB at 30 Hz (-6 dB at 20 Hz for Q = 0.5 and -12 dB/oct to 5 Hz)
Eight power amplifiers (e.g. ATI model AT6012)
Room size: >240 ft2 (>22 m2) area, >8 ft ceiling
Speaker placement measured from tweeter: 
>4 ft from wall behind it, >2 ft from side walls,
speaker separation >8 ft 
Listening distance 8 ft to 18 ft
Room acoustics: Fairly live with RT60 of 400 ms to 700 ms


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## Yad (Oct 19, 2009)

Hi everybody. I found some links about Open Enclosure (Open Baffle) and Infinite Baffle. 

http://en.wikipedia.org/wiki/Loudspeaker_enclosure#Infinite_baffle 

http://www.diysubwoofers.org/ 

http://www.troelsgravesen.dk/OBS.htm


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## sfdoddsy (Oct 18, 2007)

Spadez said:


> Hi,
> 
> 
> 1. Are these open baffle systems capable of going into the 90Hz-100Hz range?
> ...


1. Yes indeed. Mine are flat to below 20Hz. The extension depends on the drivers used, the width of the baffle, and the amount of EQ you use.

2. I'm not sure what you mean by mount plate. If you mean baffle (what you mount the speaker on) then yes it does. In general terms, a wider baffle will produce deeper bass without EQ. On the other hand, the wider the baffle the more it may affect the midrange.

3. IMHO, open baffle speakers produce the best sound you can get.

4. Yes, you can simple mount drivers on a piece of wood. Some people even get by with a single driver mount on a piece of wood. More sophisticated systems use multiple drivers, bracing and sometimes wings.

5. Research.

The Bible for open baffles is Siegfried Linkwitz and his site:

www.linkwitzlab.com

He has designed the most sophisticated systems, notable the Phoenix and Orion.

You can examine other approaches here:

http://www.diyaudio.com/forums/multi-way/123512-ultimate-ob-gallery.html

And here:

http://www.hawthorneaudio.com/

The link in my signature will take you through my build.


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## Yad (Oct 19, 2009)

I like dipoles to, but deep LF equalization usually causes limitations of the dunamic range at the lowest frequencies. It's very audible at the organ music. Steve gave some links with correct (IMHO) speakers when You use Closed Enclosure to the deepest freq. And other drivers are OE. 

Steve's dipoles looks grate :clap:

Martin Logan made the same construction: CE at bass and OE electrostatics at midbass-highs. 
I've heard that model. Sounds grate.


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## Drew Eckhardt (Oct 24, 2009)

Having built Orions and heard various other dipole implementations including Nelson Pass's BOB setup, natural sound seems to require smaller baffles with the bottom end coming from additional drivers which may have bigger baffles and/or equalization.

Theory is consistent with this - increasing baffle size for bass extension also lowers the frequency above which you get power response peaks and lobing as the rear wave sums in-phase with the front.

John Krevosky illustrates:

http://www.musicanddesign.com/Dipoles_and_open_baffles.html


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## oldbar (Feb 16, 2007)

I am actually in the process of building a 3 way.
I am using The seas L26 for bass in a ported 94 litre box also using Zaphs new driver as a mid on an open baffle with seas H1212 tweeter as well and i hope to start building by the end of this week.


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