I have two 12" woofers per side in 12" deep U frames positioned 5' from the front wall and against the side walls actively crossed over at 125Hz. They perform well without EQ. I am wondering if ideally a flat baffle would be better SQ wise. Other than the loss of LF extension, what would be the pros and cons?
Parameters of an open baffle subwoofer 'box' are among others:
- dipole separation: determines efficiency and upper frequency limit
- symmetry: determines radiation pattern
- cavity resonances: determine upper frequency limit
- mass loading: identical effect to adding mass to the cone
There are no sound quality advantages of a flat baffle as compared to an H frame. A U frame performs similar to an H frame at low frequencies. Flat baffles are used when the woofer has to run up to a higher frequency (say 500 Hz) or when there is not enough space for other options.
The 'best' open baffle bass configuration is one that maximizes dipole separation for a given size constraint or upper frequency limit. This results in higher output or lower distortion for a given output level. Symmetry is also important if you want a 'real' dipole and not something that resembles cardioid or omnipole at a part of the frequency range (which is not necessarily wrong).
- dipole separation: determines efficiency and upper frequency limit
- symmetry: determines radiation pattern
- cavity resonances: determine upper frequency limit
- mass loading: identical effect to adding mass to the cone
There are no sound quality advantages of a flat baffle as compared to an H frame. A U frame performs similar to an H frame at low frequencies. Flat baffles are used when the woofer has to run up to a higher frequency (say 500 Hz) or when there is not enough space for other options.
The 'best' open baffle bass configuration is one that maximizes dipole separation for a given size constraint or upper frequency limit. This results in higher output or lower distortion for a given output level. Symmetry is also important if you want a 'real' dipole and not something that resembles cardioid or omnipole at a part of the frequency range (which is not necessarily wrong).
Last edited:
What contributes a lot to the wonderful sound of dipoles is what's behind them in your room and how you work with that space to create great sound at your chair.
B.
B.
Thanks. It seems apparent that at the frequency they are crossed over at and the depth of the frame there is no advantage to a flat baffle. 😀
Does it take bass drivers with special design characteristic to excel in an open baffle design? or just more more size? PureAudioProjects uses 15"s ...
Last edited:
Mainly large volume displacement, highish Qts, low Fs, low nonlinear distortion, silent (well vented) motor.
OB, parameters defined?
Hi there W: listing your suggestions, with questions added:
1) large volume displacement: probably 15", 18", 21" drivers?(applied in multiples per side?)
2) highish Qts: range of suggestion?
3) low nonlinear distortion: how is that determined when purchasing drivers? *
4) silent drivers, well vented motors: how is that determined from information published by makers?*
* (by looking at Parts Express or US Speakers web site postings)*...regards, Michael
Hi there W: listing your suggestions, with questions added:
1) large volume displacement: probably 15", 18", 21" drivers?(applied in multiples per side?)
2) highish Qts: range of suggestion?
3) low nonlinear distortion: how is that determined when purchasing drivers? *
4) silent drivers, well vented motors: how is that determined from information published by makers?*
* (by looking at Parts Express or US Speakers web site postings)*...regards, Michael
1) Volume displacement (Vd) and driver size is upon your personal preferences The larger the better you need to put borders by yourself.
2) In passive systems Qts of 0,5 is considered as sweet spot but if going active, Qts becomes absolutely irrelevant. Folded baffles can raise Qts very considerably and at the same time make Fs considerably lower.
3, 4) You cannot determine it before purchase, you need to do your own internet investigation and seek for THD measurements or opinions of users. It is wise to search for highest Vd /price ratio for OB drivers becouse for this arrangement (when space doesn't matter what is very likely) it is better to have more cheap but reasonably performing drivers with large summed cone area and lower Xmax rather than one single but premium priced with maxed-out parameters...
Small sealed subs are just an opposite story.
2) In passive systems Qts of 0,5 is considered as sweet spot but if going active, Qts becomes absolutely irrelevant. Folded baffles can raise Qts very considerably and at the same time make Fs considerably lower.
3, 4) You cannot determine it before purchase, you need to do your own internet investigation and seek for THD measurements or opinions of users. It is wise to search for highest Vd /price ratio for OB drivers becouse for this arrangement (when space doesn't matter what is very likely) it is better to have more cheap but reasonably performing drivers with large summed cone area and lower Xmax rather than one single but premium priced with maxed-out parameters...
Small sealed subs are just an opposite story.
Last edited:
Linkwitz LXSub4 L26ROY
Hi
I am looking for your validation/opinion on a open baffle config: I've got a German Physiks DDD driver that would cross ofver around 200Hz and i was thinking to mate it with a Linkwitz LXSub design basically an open baffle with Seas L26Roy drivers in V configuration. I would used a Minidsp for xover and EQ (per the linkwitz adjustrements)
The question is: Linkwitz brings the L26Roy to 120Hz ; i am wondering what a push to 200-250Hz would imply in terms of SQ (distorsion)? In the driver can go to ~1KHz.
Hi
I am looking for your validation/opinion on a open baffle config: I've got a German Physiks DDD driver that would cross ofver around 200Hz and i was thinking to mate it with a Linkwitz LXSub design basically an open baffle with Seas L26Roy drivers in V configuration. I would used a Minidsp for xover and EQ (per the linkwitz adjustrements)
The question is: Linkwitz brings the L26Roy to 120Hz ; i am wondering what a push to 200-250Hz would imply in terms of SQ (distorsion)? In the driver can go to ~1KHz.
Sure... many PAP systems "look good" but utilize a rather stupid design. It's the dumb buxom blonde lady of the open baffle world.
These are all very good points. I would just add that if you are not using a driver near its resonance, the Qts value is not so important. So this is mainly a concern for the drivers used for the lowest band(s) in the speaker.
I wrote up a design philosophy on this site awhile back that might be worth plugging here:
https://www.diyaudio.com/forums/multi-way/320815-multi-ob-2.html#post5389471
I tend to use drivers without a baffle (also called "nude") for the higher bands in the loudspeaker. This helps to minimize the baffle size and as alluded to by bentoronto you want to make use of the sound coming off the back of the speaker and reflecting off of the wall (the front wall I think it is called). Large baffles tend to "get in their own way" in this regard, and when very large I can close my eyes and "hear" the structure acoustically in the room. By getting rid of the large planar baffle you let the rear sound come back freely into the room (which is what you want with an OB/dipole system), and you eliminate another potential source of resonance/vibration.
Regarding dipole bass (subwoofer) you eventually need to increase the front-to-back pathlength with a baffle. By folding the baffle you minimize it's size. So a U-frame or H-frame are good solutions. Large displacement is still required, and I have found some car audio drivers with high Qts and high Xmax can work very well. For example the IB318v3 model from Fi Car Audio:
IB3 v2 Series Archives | Fi Car Audio
This is pretty amazing in a 36" H-frame.
Last edited:
I'm a lifetime dipole fan, but after spending thousands on a dipole sub to go with my ESL63 mains, hoping for flat to 20hz, achieved mid twenties, but I didn't care for the "quality" of the bass sound. Measured flat, seemed thin.
OTOH the sound was exactly the same bass as the ESL63 only extended from upper 30's to the mid 20's, which was not worth the money. What was worth the money was how amazingly better the ESL63 performed with bass below 100 ish hz removed.
Maybe its a pure matter of taste, but IMHO the Klipsch Heresy is what bass should sound like, nice and fat, but still fast and tight.
Bottom line, dipole is great, but practically speaking and to my taste below 100hz or so transition to a real box.
OTOH the sound was exactly the same bass as the ESL63 only extended from upper 30's to the mid 20's, which was not worth the money. What was worth the money was how amazingly better the ESL63 performed with bass below 100 ish hz removed.
Maybe its a pure matter of taste, but IMHO the Klipsch Heresy is what bass should sound like, nice and fat, but still fast and tight.
Bottom line, dipole is great, but practically speaking and to my taste below 100hz or so transition to a real box.
My recommendation for woofer is at least 15 inch high quality woofer. I started out with four 10 inch vifa woofers of good quality, and this was quite good, but compared to an even better 15 inch woofer they performed quite bad. The Vifas were not silent below 40 hz. They rattled a lot and bottomed out. My Gladen rs15fa performs much better in all areas. It goes well below 40 hz, don't bottom out and is silent. In flat baffle it will bottom out, but in u baffle it performs really well.
Both of which can be simulated in Hornresp, thanks to the brilliant models developed by 'bolserst'.
Attachments
Light flabby membranes are intentionally used as distortion generators by those who have brains... but i don't really know why, is it a reason to be so incisive ?