I don't believe that's something you can generalize.
You'll have to assess your specific application (output goals, bandwidth) for quantification.
We need to consider the punch of the bass and reverberant characteristics.
I think two per side is adequate down to around 140 Hz. Four to 100 Hz, eight to 60 Hz.
A single 15 in a proper 1/4 size bass horn with a 50 Hz flare will do as well as eight high QTS, high sensitivity OB 15's. Placement is easier for better results with the OB bass and the OB bass should sound less resonant and more realistic.
Most horns (all that I have heard) that are folded like the one Olson pointed towards or suggests is really only good for an octave (the vent is a joke) or at most two and will really be colored. Four 15's in a line on an open baffle would be a better choice for the band he wants to cover.
So it's come around to "Bass Reflex vs Horn vs OB" has it? =)
OB does sound great, but it sure has its limitations, as mentioned here. Not very efficient and rarely plays very low - despite claims to the contrary. But clean!
Big boxes are great, but they can be boomy if you're not careful.. I know, I have a pair of 400L boxes now. The right driver helps. The Onken style does not need much bracing as the port structure takes care of that. It's great if you have the right driver.
Horn bass is wonderful, if you have the room. Build it into the ceiling or the basement.
Gary's "V-bass" (or whatever you would call it) is a darn good compromise. Not huge, good extension with modest EQ. Super clean. Not an easy build, tho. The table saw jig he had to build just to cut the box internals is quite a piece of work in itself!
Nothing new - just sharing.
OB does sound great, but it sure has its limitations, as mentioned here. Not very efficient and rarely plays very low - despite claims to the contrary. But clean!
Big boxes are great, but they can be boomy if you're not careful.. I know, I have a pair of 400L boxes now. The right driver helps. The Onken style does not need much bracing as the port structure takes care of that. It's great if you have the right driver.
Horn bass is wonderful, if you have the room. Build it into the ceiling or the basement.
Gary's "V-bass" (or whatever you would call it) is a darn good compromise. Not huge, good extension with modest EQ. Super clean. Not an easy build, tho. The table saw jig he had to build just to cut the box internals is quite a piece of work in itself!
Nothing new - just sharing.
So split the difference and use a box for bass below the lowest room mode and OB from sub up through midbass.
Still it is hard to get around hoffman's iron law.
I too had planned to go OB and mate with hi-eff top, but that proves to be difficult if you are trying to get extension, keep efficiency up and have it pass the WAF for living room dwelling.I went for the BR with PRs, with one AES TD15X per 4.5cuft box and two PRs. I tuned for only 10hz extension below what a sealed enclosure would deliver, F3 ~48hz iirc, which keeps group delay lower while providing less excursion and greater power handling. I'll add an IB sub if needed.
Its all about trade offs, there are no easy buttons.
Hello,
What about a Le CLeac'h bass horn (for what I know at least 5 of them have been built here in France ).
Here are 2 examples:
http://www.diyaudio.com/forums/attachment.php?attachmentid=128826&d=1236807427
http://img383.imageshack.us/i/dsc30511280x768ac0.jpg/
If you have sufficient height in your listening room then it is the perfect solution until 350Hz.
Best regards from Paris, France
Jean-Michel Le Cléac'h
What about a Le CLeac'h bass horn (for what I know at least 5 of them have been built here in France ).
Here are 2 examples:
http://www.diyaudio.com/forums/attachment.php?attachmentid=128826&d=1236807427
http://img383.imageshack.us/i/dsc30511280x768ac0.jpg/
If you have sufficient height in your listening room then it is the perfect solution until 350Hz.
Best regards from Paris, France
Jean-Michel Le Cléac'h
And I may build the first one in the USA. =) But there is much work to do in my listening room first.
What would you think about putting it in the ceiling and using the front wall as the "floor". Something like Mr. Hiraga's new room?
An OB can still be a LOT easier to implement well than a horn. The mouth flair on the omni-top will be audible in a critical listening context. Plus you still have all the cabinet resonances ++ (..especially when augmented with a bass reflex in the lower midrange). For sound reinforcement it's an excellent design, for hifi it has several things going for it, but with multiple failures as well. Suggestion: look elsewhere from the omni-top.
Also, remember that with any design you still have your amplifier's reaction to rising impedance near fs. IF the impedance curve is in the correct location, you can often compensate for baffle loss/dipole cancellation. Again, consider the Jensen Neo 15-150 16 ohms in parallel on a OB about 19" by 32". It would still need the midrange driver to fill-in between 200 Hz and up to as high as 1200 Hz, but it should give you pretty good gain for the lower midrange in an OB configuration. (..on the other hand crossing that low has several advantages, like reducing the upper freq. break-up from the Jensen's and allowing you to place the midrange high enough to alter floor bounce for a given listening position.)
Note that an OB's large reaction forces are largely a matter of mass and excursion - both necessarily relating to freq. extension. Keep the bandwidth from extending much below 75 Hz and it shouldn't cause a problem for the design.
If you want to pursue another route then Olimpiaudio.com has some exceedingly efficient 15" drivers for a sealed, aperiodic, or bass-reflex design. Not cheap though, and I'd suspect that the result, while more extended, would result in a very large cabinet. (..though in a smaller cabinet with a well done aperiodic venting, *could* get you something closer to what you are looking for.)
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I think what you guys should consider is using
DR280 (size 24" x 24") from around 130hz up to 1000hz. I just guess that a horn lower mid may integrate better with an AH-425 than open baffle.
From 130hz and below, use BudP's designed cardoid sub and rotate it 90 degree. So, it will sit below the DR280.
I suggest open baffle servo subs by GR-Research and Rythmik.
GR-Research will have its V1 at RMAF; supposely it sounds very good and the open baffle servo sub is good up to 200Hz. Maybe Lynn can listen to it there and let us know what you think.
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OB bass don't need to be big. Just look at orion or Phoenix. Mine uses 2x10" /ch, just cheap $14 woofers and I equalise them to 20Hz Q=0.5.
Don't know how loud you guys listen to your system, but mine is loud enough for the other half to complain.
The thing here is: active line-level eq. Passive system can forget OBs as they won't have the ability to eq the bass.
Anyway I hope the Ariel replacement will be a great system (and not expensive!) to build.
Don't know how loud you guys listen to your system, but mine is loud enough for the other half to complain.
The thing here is: active line-level eq. Passive system can forget OBs as they won't have the ability to eq the bass.
Anyway I hope the Ariel replacement will be a great system (and not expensive!) to build.
This is an interesting discussion, I appreciate hearing peoples opinions! OB v. Horn, etc. Size seems to be an issue for both of these - and it seems like horns have it worse, on average. It is possible to build sensitive (>90dBspl) OB's that have modest size and don't need 20dB EQ - it just takes a careful design, and probably has to be a 4 way (and it would have an exceptionally regular off axis response).
While horns can have very smooth off-axis responses, their directivity is rising - so radiation at right angles to the design axis are bass and mid heavy. OB, if done well, can have an off axis response that is the almost the same as on axis, just lower in level. I'd guess this might have a big impact on their perceived presentation. Similarly, I would presume horns wouldn't step up as strong a 'reverberant' field, as OBs have symmetrical front and rear radiation (again, design specific). I'd guess this is why horns are perceived as rendering more detail, while OBs are known for the 'spaciousness' of their sound. Just guesses though, I have no experience with domestic horns.
I've had a different experience with 15" OB bass drivers. I use MJK's Alpha15a design in a 16" by 16" by 17" H frame, one per side. I measured outdoor (again) two days ago, with 2.83Vrms in, at 1 meter, mic 8" off the ground, a single H frame is 94.5dBSPL sensitive at 50Hz. Add 6dB for the other side, for a total of 100.5dBspl. Due to the drivers Qes/Qms, there is no need for eq, being flat from 40-100Hz. Clearly, in this bandwidth, it is easy to hit +105dB in room. Who here is listening at an average of 110dBspl? And below 40-50Hz, IMO, is sealed/bandpass sub territory.
I have two issues with MJK's h-frame - its footprint, and its distortion spectrum mid-bass. But I'm finishing a design that has a 11" by 13" footprint, need no EQ, is almost as sensitive, has more output, and lower distortion, for almost the same cost.
So in summary, unless your in a large room, and listening at very high levels for long periods, OB bass is easy to pull off, particularly if you have the space. In domestic situations (less spl needs, more WAF needed), OB is a cinch.
While horns can have very smooth off-axis responses, their directivity is rising - so radiation at right angles to the design axis are bass and mid heavy. OB, if done well, can have an off axis response that is the almost the same as on axis, just lower in level. I'd guess this might have a big impact on their perceived presentation. Similarly, I would presume horns wouldn't step up as strong a 'reverberant' field, as OBs have symmetrical front and rear radiation (again, design specific). I'd guess this is why horns are perceived as rendering more detail, while OBs are known for the 'spaciousness' of their sound. Just guesses though, I have no experience with domestic horns.
I've had a different experience with 15" OB bass drivers. I use MJK's Alpha15a design in a 16" by 16" by 17" H frame, one per side. I measured outdoor (again) two days ago, with 2.83Vrms in, at 1 meter, mic 8" off the ground, a single H frame is 94.5dBSPL sensitive at 50Hz. Add 6dB for the other side, for a total of 100.5dBspl. Due to the drivers Qes/Qms, there is no need for eq, being flat from 40-100Hz. Clearly, in this bandwidth, it is easy to hit +105dB in room. Who here is listening at an average of 110dBspl? And below 40-50Hz, IMO, is sealed/bandpass sub territory.
I have two issues with MJK's h-frame - its footprint, and its distortion spectrum mid-bass. But I'm finishing a design that has a 11" by 13" footprint, need no EQ, is almost as sensitive, has more output, and lower distortion, for almost the same cost.
So in summary, unless your in a large room, and listening at very high levels for long periods, OB bass is easy to pull off, particularly if you have the space. In domestic situations (less spl needs, more WAF needed), OB is a cinch.
Member
Joined 2003
The thoughts behind the system are:
To use the Lowther from 20 kHz to 300 Hz.
Use the Delta 8 from 300 to wherever it quits.
Use the Tang Band Cardioid bass up to perhaps 70 Hz.
As all will be EnABL'd, they will have somewhat better performance in low frequency, without baffle support, than is typical. We shall see how much better.
I wanted the Delta 8 in there because it can handle large amounts of power and should be able to portray the all important upper bass better than the Lowther ever could.
The Tang Bands are 10 dB less sensitive, but they have 12mm of xmax and will be driven by a separate bass amp and should be able to reach 103 db at 20 Hz very clean. This will be rather more than enough for my circumstances.
I also have plans laid for a Berringer 2496, with replaced DAC's (the designer of the Alpha Dac wants to help here) to get rid of the embedded op amp buffer stage in their DAC and replacement of the output op amps with transformer volume controls, with 24 steps and isolation, to match voltage out to the various amps, without using the Berringer's digital volume control, which looses bits. This will allow the Dacs to run without buffering the DC, just gap the primary. I also intend to provide an isolation transformer volume control on the input, as a main volume control. So, the Berringer is really only needed because it has a great set of DSP driven crossover circuits, is quiet, and already sorted.
The final insult will come from using Gary Pimm's front end from the push pull SS Tabor rev 2, into a PP to SE nickle core interstage, to... a 300 B, to drive the Lowther. SS amps, running at tube voltages, appear to be much more linear than when used as current devices only. So, SS driver stages driving a 300 B should be a very pretty sound.
The Audio Prisim has our OPT's in it and is a superb amplifier, sort of an insult to only use it to 300 Hz. And finally Sure tri-path 100 watt amps for the Tang Bands.
I realize that this is anathema in a general sense. However, I have heard all of the components, in various stages of completeness and am confident I will have what I am looking for.
And, all of this is just weird enough to suit my nature.
Bud
To use the Lowther from 20 kHz to 300 Hz.
Use the Delta 8 from 300 to wherever it quits.
Use the Tang Band Cardioid bass up to perhaps 70 Hz.
As all will be EnABL'd, they will have somewhat better performance in low frequency, without baffle support, than is typical. We shall see how much better.
I wanted the Delta 8 in there because it can handle large amounts of power and should be able to portray the all important upper bass better than the Lowther ever could.
The Tang Bands are 10 dB less sensitive, but they have 12mm of xmax and will be driven by a separate bass amp and should be able to reach 103 db at 20 Hz very clean. This will be rather more than enough for my circumstances.
I also have plans laid for a Berringer 2496, with replaced DAC's (the designer of the Alpha Dac wants to help here) to get rid of the embedded op amp buffer stage in their DAC and replacement of the output op amps with transformer volume controls, with 24 steps and isolation, to match voltage out to the various amps, without using the Berringer's digital volume control, which looses bits. This will allow the Dacs to run without buffering the DC, just gap the primary. I also intend to provide an isolation transformer volume control on the input, as a main volume control. So, the Berringer is really only needed because it has a great set of DSP driven crossover circuits, is quiet, and already sorted.
The final insult will come from using Gary Pimm's front end from the push pull SS Tabor rev 2, into a PP to SE nickle core interstage, to... a 300 B, to drive the Lowther. SS amps, running at tube voltages, appear to be much more linear than when used as current devices only. So, SS driver stages driving a 300 B should be a very pretty sound.
The Audio Prisim has our OPT's in it and is a superb amplifier, sort of an insult to only use it to 300 Hz. And finally Sure tri-path 100 watt amps for the Tang Bands.
I realize that this is anathema in a general sense. However, I have heard all of the components, in various stages of completeness and am confident I will have what I am looking for.
And, all of this is just weird enough to suit my nature.
Bud
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Mr. Purvine, you would need a web-site!
Or at least a blog. There are to many of your ideas scattered in these forums.cuibono, this is pretty significant... I guess that it would definitely match a waveguide/horn.
Remember Magnetar's system? 5 10'' woofers per side? And it was quite compact also..
Pano is suckering you guys here. I was there, during a typical Portland thunderstorm trapped in the Columbia river basin. Gary put on a record, as in vinyl, with what he thought was a good rendition of a thunderstorm. The two, inside and outside, were at the same level in the living room, including the house shaking and the window glass obviously bowing. Of course a small amount of EQ and a 600 watt crown amp will do this, but look at the pictures, see if you think it is possible.
And this is clean enough to pick out any bass viol, from an orchestral group and follow it , without strain.
Bud
Attachments
Something like 85% recycled denim (that is a lot of blue jeans) ... Bob (at CSS) is selling managable quantities of the 1/2" (5/8") stuff. A god send. We are now using it in place of the vinatge cotton or woll felt we had been using. We are still working our way thru a full bat of 3 1/2". The microTowers use this. Good stuff.
http://www.bondedlogic.com/
dave
To give credit where it is due, the math behind much of Gary's work comes from our own John K at this site. http://www.musicanddesign.com/index.html So, if you want to explore other cardioid bass schemes, make sure you get the real information.
Bud
Bud
Well, that last post certainly set the cat amongst the pigeons!
I'm not married to any one approach - but I do think it's useful to partition deep bass (20~80 Hz) from the 80~800 Hz range. The solutions are different, and the interactions with the room are different as well. Deep bass is mostly below the lowest-frequency room mode, and is the domain of Hoffman's Iron Law, which is inescapable.
Setting aside the choice of technology, the dominant problems in the 80~800 Hz range are room modes, followed by box modes and panel vibration. The drivers are inherently flat, since they are in the piston band, so they are essentially blameless here. There are worries about delta-inductance and arcana of magnet construction, but those are minor compared to room modes, box modes, and panel vibration.
If anyone doubts that box modes or panel vibration are audible, by the way, just put your ear against the side panel of conventional loudspeaker, listen for a while with bass-range or vocal music, than move back to your chair. The droning coloration you heard while listening to the box will still be audible from the sitting position - in fact, now that you know what it sounds like, you won't be able to ignore it!
The marvelous thing about OB's is that this coloration is finally, and wonderfully, all gone. But the increase in excursion (below baffle peak) is no small matter. The added excursion (compared to a closed box) is another 6 dB per octave - of course, it can equalized and additional watts thrown at it, but the extra distortion is there to stay (unless servo feedback is used). The OB increase in excursion is [Ion top of[/I] the normal 12 dB increase in excursion per octave of a closed-box speaker.
Ideally, this would be offset by an increase in cone area - but as you can imagine, the cone area necessary to keep excursion low at the lowest frequencies would truly be immense - the size of a wall.
The baffle peak is a little troubling as well. It is caused by the rear wave coming around the baffle to the front - so it appears in the time domain as well as the frequency domain. Subjectively, it is much less offensive than box modes and panel vibrations, because those have much higher Q's and take a lot longer to ring down to zero - that's the droning sound you hear coming from the side of a conventional box.
Each type of approach has measurable, and with listening practice, audible faults. Once you know what box modes and panel vibrations sounds like, they are hard to accept. Once you get used to the effortless quality of horn-loaded bass - especially with piano and symphonic music - direct-radiators don't sound as good. Different people are sensitized to different types of coloration, thus the preference for different types of loudspeakers, electronics, and source materials.
I have had the misfortune of working with loudspeakers for a while, and notice odd sounds that most others don't hear. That doesn't increase my appreciation of hifi, it makes more difficult to listen, since much of the time all I'm aware of is a checklist of faults. The objectivists might say that it's all in my head - and well, yes, it is[/I} all my head, since I can't hear what others are hearing. Who's head would it be in, anyway, if not my own? How can I imagine what anyone else is hearing? I'm not good at that kind of thing.
Less facetiously, I usually hear an improvement when a measurable fault is corrected - although not always. I'm not very sensitive to phase distortion, and others are. Some people go nuts when the absolute phase (of both channels) is inverted, but all I hear is a subtle - sometimes very subtle - timbral change on some instruments, less than a change in seating position, or a track-to-track difference in EQ.
What I do hear - in other words, what I care about when listening to a loudspeaker - are cabinet colorations, as well as fairly obvious dynamic-range limitations. These appear to be the major tradeoffs.
I'm not married to any one approach - but I do think it's useful to partition deep bass (20~80 Hz) from the 80~800 Hz range. The solutions are different, and the interactions with the room are different as well. Deep bass is mostly below the lowest-frequency room mode, and is the domain of Hoffman's Iron Law, which is inescapable.
Setting aside the choice of technology, the dominant problems in the 80~800 Hz range are room modes, followed by box modes and panel vibration. The drivers are inherently flat, since they are in the piston band, so they are essentially blameless here. There are worries about delta-inductance and arcana of magnet construction, but those are minor compared to room modes, box modes, and panel vibration.
If anyone doubts that box modes or panel vibration are audible, by the way, just put your ear against the side panel of conventional loudspeaker, listen for a while with bass-range or vocal music, than move back to your chair. The droning coloration you heard while listening to the box will still be audible from the sitting position - in fact, now that you know what it sounds like, you won't be able to ignore it!
The marvelous thing about OB's is that this coloration is finally, and wonderfully, all gone. But the increase in excursion (below baffle peak) is no small matter. The added excursion (compared to a closed box) is another 6 dB per octave - of course, it can equalized and additional watts thrown at it, but the extra distortion is there to stay (unless servo feedback is used). The OB increase in excursion is [Ion top of[/I] the normal 12 dB increase in excursion per octave of a closed-box speaker.
Ideally, this would be offset by an increase in cone area - but as you can imagine, the cone area necessary to keep excursion low at the lowest frequencies would truly be immense - the size of a wall.
The baffle peak is a little troubling as well. It is caused by the rear wave coming around the baffle to the front - so it appears in the time domain as well as the frequency domain. Subjectively, it is much less offensive than box modes and panel vibrations, because those have much higher Q's and take a lot longer to ring down to zero - that's the droning sound you hear coming from the side of a conventional box.
Each type of approach has measurable, and with listening practice, audible faults. Once you know what box modes and panel vibrations sounds like, they are hard to accept. Once you get used to the effortless quality of horn-loaded bass - especially with piano and symphonic music - direct-radiators don't sound as good. Different people are sensitized to different types of coloration, thus the preference for different types of loudspeakers, electronics, and source materials.
I have had the misfortune of working with loudspeakers for a while, and notice odd sounds that most others don't hear. That doesn't increase my appreciation of hifi, it makes more difficult to listen, since much of the time all I'm aware of is a checklist of faults. The objectivists might say that it's all in my head - and well, yes, it is[/I} all my head, since I can't hear what others are hearing. Who's head would it be in, anyway, if not my own? How can I imagine what anyone else is hearing? I'm not good at that kind of thing.
Less facetiously, I usually hear an improvement when a measurable fault is corrected - although not always. I'm not very sensitive to phase distortion, and others are. Some people go nuts when the absolute phase (of both channels) is inverted, but all I hear is a subtle - sometimes very subtle - timbral change on some instruments, less than a change in seating position, or a track-to-track difference in EQ.
What I do hear - in other words, what I care about when listening to a loudspeaker - are cabinet colorations, as well as fairly obvious dynamic-range limitations. These appear to be the major tradeoffs.