OB bass advice request
Hello all! I'm looking for an OB frame design for 2 Peerless SLS-P830669 per channel. Here are two compact designs I've patterned after designs by Gainphile and others. A compact design is needed to please my darling wife. These drivers are rated for 30-2000 Hz in a box (*spit*) and Qts of .54. I assume I don't need to mention the phase arrangement here to you smart folks. Tweeter will be Heil AMT Mid that will begin at 1000 Hz.
Several questions:
1) do either of these designs have sonic flaws that I need to be aware of?
2) is it flawed to expect these drivers to project well up to 1000 Hz if they are not forward facing? Thus, should I add an OB Mid to the speaker and do something like Bass>200Hz>Mid>1000Hz>tweeter?
Hello all! I'm looking for an OB frame design for 2 Peerless SLS-P830669 per channel. Here are two compact designs I've patterned after designs by Gainphile and others. A compact design is needed to please my darling wife. These drivers are rated for 30-2000 Hz in a box (*spit*) and Qts of .54. I assume I don't need to mention the phase arrangement here to you smart folks. Tweeter will be Heil AMT Mid that will begin at 1000 Hz.
Several questions:
1) do either of these designs have sonic flaws that I need to be aware of?
2) is it flawed to expect these drivers to project well up to 1000 Hz if they are not forward facing? Thus, should I add an OB Mid to the speaker and do something like Bass>200Hz>Mid>1000Hz>tweeter?
1. Depends on what frequency range you want it to play. The sideways mounting creates resonances so it lowers the usable range by a bit. With 12" drivers you'd be pushing it to go above ~ 125 hz with such an enclosure.
Here is a polar plot of a mini W-frame with 3" drivers, usable up to about 500 hz with some margin until the peak. So with 12" drivers you could expect similar but shifted down 2 octaves hence 125 hz.
It is a great setup in the bass though.
2. Yes, I would definently go with a midwoofer in that case, a 6-7" midwoofer would fit nicely. But most importantly you could use a smaller and flat baffle for it to avoid the resonance issues of the woofers.
Attachments
Last edited:
I have a seas w22 excel and 125hz is about the limit - crossed at 100 hz it moves signifantly - i dont see the advantage of a smaller midwoofer when you are about to cross at 1000hz
You might take a look at linkwitzlab.com for H and W bin - you cannplay with crossoverfrequencies between 80 and 250 hz - finfing an optimum between too much excursion for your midwoofer and hearing resonances from your woofercabinetconstruction
You have a dsp?
You might take a look at linkwitzlab.com for H and W bin - you cannplay with crossoverfrequencies between 80 and 250 hz - finfing an optimum between too much excursion for your midwoofer and hearing resonances from your woofercabinetconstruction
You have a dsp?
Last edited:
b4bz, using sideways openings will mess high frequency and perhaps loose some "detail" and efficiency. Don't even dream of crossing those at 1kHz, radiation pattern will be far from dipole there.
My choice would be like LX521 or Gainphile S19, crossed somewhere around 2-500Hz - requires lots of testing of bass and mid module dispersion and distortion behaviour!.
My choice would be like LX521 or Gainphile S19, crossed somewhere around 2-500Hz - requires lots of testing of bass and mid module dispersion and distortion behaviour!.
Last edited:
I wanted to to try the low distortion SB Acoustic ceramic drivers in an open baffle. Here I tried the 1" 4" and 8" ceramic drivers in an active crossover setup
Along with some $44 12" 14mm Xmax JBL GT5 subwoofers for bass ("1.9 cubic ft 25hz 3" port") just for fun.
Overall the sound is incredibly detailed with great imaging, albeit a little cold for my taste. I added some OT19NC00-04 3/4" ring radiator tweeters to the backs of the SB acoustic tweets out of phase to add some extra air! I have since added some Allo Volt+D amps to warm up the sound and it did the trick, but..
These are amazing for 2 channel listening but the goal was to replace that current setup in the background. For my HT reference multichannel mains that consist of Seas H1212 1" Aluminum/Magnesium dome, Ascendant audio high Xmax XBL^2 6.5's and TC Sounds 1000 10". I was content with these for many years but I want to try out these new breeds of ultra low distortion drivers.
The SB 1" Ceramic tweeters are a definite improvement! I do now find that I prefer the MTM sound and presence for movies much much more, and the warmth of the poly midbass. So the hunt continues! I am currently designing a high efficiency PA driver OB MTM setup for multichannel next. It's a great time to be alive!
Along with some $44 12" 14mm Xmax JBL GT5 subwoofers for bass ("1.9 cubic ft 25hz 3" port") just for fun.
Overall the sound is incredibly detailed with great imaging, albeit a little cold for my taste. I added some OT19NC00-04 3/4" ring radiator tweeters to the backs of the SB acoustic tweets out of phase to add some extra air! I have since added some Allo Volt+D amps to warm up the sound and it did the trick, but..
These are amazing for 2 channel listening but the goal was to replace that current setup in the background. For my HT reference multichannel mains that consist of Seas H1212 1" Aluminum/Magnesium dome, Ascendant audio high Xmax XBL^2 6.5's and TC Sounds 1000 10". I was content with these for many years but I want to try out these new breeds of ultra low distortion drivers.
The SB 1" Ceramic tweeters are a definite improvement! I do now find that I prefer the MTM sound and presence for movies much much more, and the warmth of the poly midbass. So the hunt continues! I am currently designing a high efficiency PA driver OB MTM setup for multichannel next. It's a great time to be alive!
Attachments
Last edited:
An update on my post #2810. I've swapped the Mini-K's out for some Lii Audio Crystal 10's on OB. So I'm all Open Baffle now! Loving the sound out of these paired with the GRS-15's. Planing on building a more permanent, solid wood baffle system with dual 15's on each side soon. I might even work on finishing the basement too. 
Stay tuned!
Stay tuned!Attachments
The Lii's look like they could use some treble extension:
GRT-145W-8
-when available, look to these drivers for OB mid-bass replacement (with some resistance from a smaller-than-normal gauge inductor to net a higher Qts):
BIANCO-15OB350
GRT-145W-8
-when available, look to these drivers for OB mid-bass replacement (with some resistance from a smaller-than-normal gauge inductor to net a higher Qts):
BIANCO-15OB350
Hello.
Looking to learn about OB. Never tried them, and wondering if my listening room and location would be good for OB or just non-starters. At Linkwitz Lab website I noted he recommends not absorbing the back wave and positioning the speakers at a minimum at 1 meter from the back wall. Looking into the first 15 pages in this thread I see many speakers appear to be further from 1 m away from the back wall, but some that seem to be closer too.
My room is 5 x 4.8 x 2.4 meters, and I'm installing room treatments mostly to reduce reverberation at lower frequencies. Front wall and ceiling covered (and absorbing), back wall half-covered with absorption, half with a diffusor. Front wall will be absorbing, so maybe an issue per Linkwitz's note?
Speakers stand 7-8 feet apart, and they can be located up to 1m away from back wall. I sit at the middle point at 7 or 8 feet from the speakers.
FWIW: fully active 4-way system, with two sealed subs (Rythmiks in DIY box).
Eager to learn! If you know of a good article or thread, I'm quite interested. I haven't been able to find it.
Looking to learn about OB. Never tried them, and wondering if my listening room and location would be good for OB or just non-starters. At Linkwitz Lab website I noted he recommends not absorbing the back wave and positioning the speakers at a minimum at 1 meter from the back wall. Looking into the first 15 pages in this thread I see many speakers appear to be further from 1 m away from the back wall, but some that seem to be closer too.
My room is 5 x 4.8 x 2.4 meters, and I'm installing room treatments mostly to reduce reverberation at lower frequencies. Front wall and ceiling covered (and absorbing), back wall half-covered with absorption, half with a diffusor. Front wall will be absorbing, so maybe an issue per Linkwitz's note?
Speakers stand 7-8 feet apart, and they can be located up to 1m away from back wall. I sit at the middle point at 7 or 8 feet from the speakers.
FWIW: fully active 4-way system, with two sealed subs (Rythmiks in DIY box).
Eager to learn! If you know of a good article or thread, I'm quite interested. I haven't been able to find it.
That’s similar to my room, you should be fine. I played with placement, and found I liked about 1.25 m from rear wall. OB’s load the room differently than closed box (with the inherent 90 degree off axis cancellation), and I think you will likely find less absorption and more dispersion enhances.
The Linkwitz site it the best reference I have read. Another good one, if you want to deal with extension of bottom end, is to look at hframe publications by Martin King.
I haven’t personally had much luck with subs supplementing lowest bass, others have.
I’m working on mine now, trying to take a base PureAudioProject trio 15 TB to the next level with various changes, including waveguided tweeter(s)...to improve dispersion vs the 8” fullrange. Studying the work of Joseph Crowe (he has lots of great bids on YouTube, some of which are helpful for OB).
The Linkwitz site it the best reference I have read. Another good one, if you want to deal with extension of bottom end, is to look at hframe publications by Martin King.
I haven’t personally had much luck with subs supplementing lowest bass, others have.
I’m working on mine now, trying to take a base PureAudioProject trio 15 TB to the next level with various changes, including waveguided tweeter(s)...to improve dispersion vs the 8” fullrange. Studying the work of Joseph Crowe (he has lots of great bids on YouTube, some of which are helpful for OB).