View Full Version : Open Baffle Speakers
Who else on here :-
Uses these, if so which flavour..
Has Used them but decided they were not for them and why they thought that.
Berni217
27-10-2024, 12:17
Hi Rob,
I had and still have the Auditorium 23 Solovox, which has provided lots of joy over the years.
They have moved to my second system after my decision to build an all Shindo system!
B.
Sent from my iPhone using Tapatalk
Hi Bernard. OBs seen to be a bit thin on the ground with the members here. I have not seen the Auditorium 23 Solovox speakers before and I see they use one full range speaker.
I played with FR speakers some years ago but in a DIY back loaded horn cabinet (Fostex and Lowther) and other designs like the Zigmahornets which for the ease of build were really quite amazing.
dave2010
28-10-2024, 11:16
I made some once, but they were a very cheap stop gap. Bass response is going to be poor unless they are really big. They will avoid obvious cabinet resonances, though may exhibit other problems. Chances are they will have an uneven and weak bass response, and making ones big enough [infinite baffle] to overcome some of the problems is not going to work in many houses these days.
Speaker and driver design has moved on since such systems were even considered.
I heard some open baffle speakers made by Ali Tait of this parish. I was surprised at the amount of bass they produced given the relatively narrow width of the baffle.
In theory one would need one half of the baffle to be one half wavelength wide, to prevent cancellation of the sound coming from the rear of the drive unit with that from the front. So at 40Hz, the wavelength is 8.5 metre, implying the width of the OB be a similar size. Clearly this is a large, if not an unachievable dimension, but in practice it seems one can get away with a much smaller width.
This is one of my OBs (Lampizator design) Which have a good bass response and are a great listen IMO of course.
https://i.imgur.com/OM0s2sF.jpg
Is the lower bass unit an OB design?
Never owned any or built any but the Linkwitz LX521 is by far the best example I've heard:
https://www.linkwitz.com/lx521/
Is the lower bass unit an OB design?
Yes, 15" Eminence.
Pigmy Pony
29-10-2024, 07:38
Never owned any or built any but the Linkwitz LX521 is by far the best example I've heard:
https://www.linkwitz.com/lx521/
Thanks in no small part to the dipole subs. Heard them again at the weekend, they really are quite special.
Yes, 15" Eminence.
Does the lower unit with the Eminance drive unit have side panels? Otherwise I can't see how rear wave cancellation is prevented.
Does the lower unit with the Eminance drive unit have side panels? Otherwise I can't see how rear wave cancellation is prevented.
No they don't. The build plans for these speakers do not include any. Might be worth me trying some? They sound fine to me as they are but......
dave2010
29-10-2024, 12:38
[QUOTE=Puffin;1381657]This is one of my OBs (Lampizator design) Which have a good bass response and are a great listen IMO of course.
Image here …
What do they look like at the back? Also do you have critical distances between the speaker and the walls behind, and/or any sound absorbing material [furnishings] there?
Have you tried measuring the responses in the room? They don’t look significantly bigger - maybe even smaller - than the cheap and not so nice ones I made years ago when I was experimenting with Hafler surround sound.
[QUOTE=Puffin;1381657]This is one of my OBs (Lampizator design) Which have a good bass response and are a great listen IMO of course.
Image here …
What do they look like at the back? Also do you have critical distances between the speaker and the walls behind, and/or any sound absorbing material [furnishings] there?
Have you tried measuring the responses in the room? They don’t look significantly bigger - maybe even smaller - than the cheap and not so nice ones I made years ago when I was experimenting with Hafler surround sound.
Pic of the rear panel.
https://i.imgur.com/NFNj4zF.jpg
Halfway Tree
29-10-2024, 13:40
https://www.linkwitz.com/lx521/[/QUOTE]
I own the ones Martin heard about 10 years ago when I first built them and wouldn't change them for any other speaker. I bought the plans directly from Siegfried Linkwitz for about $125 - best money I've ever spent on hi-fi. I've owned true ribbon Maggies (and still do) and the LX521s are superior in just about every way IMO.
The site Martin has linked to is the current commercial site run by Dr. Frank Brenner who has the license to produce these speakers following the death of Linkwitz in 2018.
Linkwitz' own site which is considered by many to be the bible for OB design is still going and can be found here - https://www.linkwitzlab.com/ (https://www.linkwitzlab.com) He was a very generous man who published his research for all to use.
Steve, thanks for your kind comments and it was great to see you on Sunday. I was so happy to get the LX521s to work really well in that small room - a bit of judicious DSP to get rid of a couple of narrow but large bass peaks was all it took really. The FR was much smoother than I expected.
BTW, there's a pair of the earlier LX521.3s for sale on PFM if anyone is really interested. Amps are included so a bit of a bargain at £3k.
I own the ones Martin heard about 10 years ago when I first built them and wouldn't change them for any other speaker. I bought the plans directly from Siegfried Linkwitz for about $125 - best money I've ever spent on hi-fi. I've owned true ribbon Maggies (and still do) and the LX521s are superior in just about every way IMO.
The site Martin has linked to is the current commercial site run by Dr. Frank Brenner who has the license to produce these speakers following the death of Linkwitz in 2018.
Linkwitz' own site which is considered by many to be the bible for OB design is still going and can be found here - https://www.linkwitzlab.com/ (https://www.linkwitzlab.com) He was a very generous man who published his research for all to use.
Steve, thanks for your kind comments and it was great to see you on Sunday. I was so happy to get the LX521s to work really well in that small room - a bit of judicious DSP to get rid of a couple of narrow but large bass peaks was all it took really. The FR was much smoother than I expected.
BTW, there's a pair of the earlier LX521.3s for sale on PFM if anyone is really interested. Amps are included so a bit of a bargain at £3k.
That is a bargain. My room is too narrow to do them justice unfortunately.
One of those speakers that makes most others at any price sound like toys.
Ali Tait's yer guy for all things OB
He's played around with many different sets in his system, knows how they work inside out.
I'd PM him Rob, or hopefully he'll see your thread here.
Who else on here :-
Uses these, if so which flavour..
Has Used them but decided they were not for them and why they thought that.
Ali Tait's yer guy for all things OB
He's played around with many different sets in his system, knows how they work inside out.
I'd PM him Rob, or hopefully he'll see your thread here.
I have heard some OBs Ali made and demonstrated at AoS's first and (so far) only get-together held at Stoke many years ago.
As I mentioned in post 5, I was very impressed by the amount of bass they could produce with a baffle of comparatively narrow width: much narrower than I thought would be needed.
In fact his system was one of the best of those demonstrated that day.
My take on my OBs are that they are as open a sound I have heard since I started this malarkey. I can say also that the level of detail and "rightness" are spot on. Of course someone elses "rightness" may be a world away from mine.
For me,
could see the flaws?
Mid and top were top notch,
different OB designs fell down in the bass.
Heard a fair few different approaches at various Owsten get togethers, always something seemed not quite right, even Ali's designs.
Disjointed and almost feeling "out of phase".
Maybe crossover improvement is a thing to look at?
Bass seemed lacking, for my ears a well integrated pair of subs would have made a big difference.
Just a taste thing of course, as always.
OB designs have essentially a dipole polar pattern, so integration with a sub-woofer will always be difficult.
That was a prime criticism of the Bowers & Wilkins DM70 speaker with an electrostatic unit atop of a large IB woofer.
I have tried using a sub-woofer with Quad ESLs, and despite comprehensive control of the roll-off, amplitude and phase, I was never happy with the results.
For me,
could see the flaws?
Mid and top were top notch,
different OB designs fell down in the bass.
Heard a fair few different approaches at various Owsten get togethers, always something seemed not quite right, even Ali's designs.
Disjointed and almost feeling "out of phase".
Maybe crossover improvement is a thing to look at?
Bass seemed lacking, for my ears a well integrated pair of subs would have made a big difference.
Just a taste thing of course, as always.
Pretty much my impression - the bass is never quite right. It is on the Linkwitz, but that uses a different arrangement.
Really, I don't think there is any advantage over a box loudspeaker, all else being equal.
Bass seemed lacking, for my ears a well integrated pair of subs would have made a big difference.
Perhaps I should have said earlier that I have successfully added 2 Subs.
Halfway Tree
31-10-2024, 16:08
For me,
could see the flaws?
Mid and top were top notch,
different OB designs fell down in the bass.
Heard a fair few different approaches at various Owsten get togethers, always something seemed not quite right, even Ali's designs.
Disjointed and almost feeling "out of phase".
Maybe crossover improvement is a thing to look at?
Bass seemed lacking, for my ears a well integrated pair of subs would have made a big difference.
Just a taste thing of course, as always.
One of the obstacles to overcome with dipole bass (other than lack of output due to cancellation) is that it can easily become lumpy and as Gary says disjointed. This is due to the backwave either reinforcing or cancelling the frontwave. Essentially it's a form of comb filtering. If you have DSP the peaks can usually be dealt with easily enough, but nulls - well, there is nothing you can do about them with DSP. Luckily moving the speaker around can often solve the problem, but at a show you don't always have that luxury. If the peaks and nulls are narrow then our brain tends to solve the problem for us, but it can certainly look ugly on a frequency sweep. Absorption is a no-no with a dipole and only serves to muck up the FR even more. Diffusion works well.
I remember hearing some Maggies at a Cranage show set up by the commercial distributor about a foot from the front wall with a matress behind them. They sounded awful, with no bass to speak of and no sense of depth or imaging. I really don't know what they were thinking.
Halfway Tree
31-10-2024, 16:42
Pretty much my impression - the bass is never quite right. It is on the Linkwitz, but that uses a different arrangement.
Really, I don't think there is any advantage over a box loudspeaker, all else being equal.
Not sure if you mean dipoles in general or just the bass Martin, but I'll presume you just mean bass output. Like nearly everything in this hobby, pros and cons in dipole bass.
Cons
Lack of output - can be mitigated with big drivers or long throw drivers, DSP and folding the baffle. I measured -4dB@20Hz in the room I was in at Barnsley. Don't remember the SPL but around 85dB I would guess.
Lack of room pressurisation - dipoles can't pressurise a room like a sealed box or ported speaker can. You won't get that sensation of a bass drum hit that's as much felt as heard.
Pros
Excites fewer room modes. There's a null to the sides so dipoles tend to be less boomy because of this and if designed correctly can be more articulate than many box speakers.
Image placement. A good dipole can retain image placement in the bass region because of its figure 8 dispersion pattern. Almost all box speakers (cardioids excepted) are omni in the bass region.
Here's a paragraph from the paper Linkwitz submitted to the AES in 1998. (https://www.linkwitzlab.com/AES%2798/aes-98.htm) Warning: some heavy maths way above my level. :)
"A number of listeners have observed that the quality of bass is different whether reproduced by a monopolar, i.e. omnidirectional woofer, or a dipolar, i.e. directional, figure-of-eight radiating woofer. The bass "boom" often heard with an omnidirectional source is less pronounced with a directional one. Furthermore, low frequency sonic detail can be presented with greater resolution and life likeness from a dipolar woofer. While the "boom" may enhance the impact of movie sound effects in some instances, it is undesirable for accurate reproduction of musical instruments and voices. It must be acknowledged, though, that upon first exposure to bass from a dipole woofer some listeners prefer the generic loudspeaker bass, possibly because their primary sonic reference is amplified sound and other box speakers. However, after a period of acclimatization the preference changes when accompanied by attention and reference to acoustic instrument sounds and voices."
Not sure if you mean dipoles in general or just the bass Martin, but I'll presume you just mean bass output. Like nearly everything in this hobby, pros and cons in dipole bass.
Cons
Lack of output - can be mitigated with big drivers or long throw drivers, DSP and folding the baffle. I measured -4dB@20Hz in the room I was in at Barnsley. Don't remember the SPL but around 85dB I would guess.
Lack of room pressurisation - dipoles can't pressurise a room like a sealed box or ported speaker can. You won't get that sensation of a bass drum hit that's as much felt as heard.
Pros
Excites fewer room modes. There's a null to the sides so dipoles tend to be less boomy because of this and if designed correctly can be more articulate than many box speakers.
Image placement. A good dipole can retain image placement in the bass region because of its figure 8 dispersion pattern. Almost all box speakers (cardioids excepted) are omni in the bass region.
Here's a paragraph from the paper Linkwitz submitted to the AES in 1998. (https://www.linkwitzlab.com/AES%2798/aes-98.htm) Warning: some heavy maths way above my level. :)
"A number of listeners have observed that the quality of bass is different whether reproduced by a monopolar, i.e. omnidirectional woofer, or a dipolar, i.e. directional, figure-of-eight radiating woofer. The bass "boom" often heard with an omnidirectional source is less pronounced with a directional one. Furthermore, low frequency sonic detail can be presented with greater resolution and life likeness from a dipolar woofer. While the "boom" may enhance the impact of movie sound effects in some instances, it is undesirable for accurate reproduction of musical instruments and voices. It must be acknowledged, though, that upon first exposure to bass from a dipole woofer some listeners prefer the generic loudspeaker bass, possibly because their primary sonic reference is amplified sound and other box speakers. However, after a period of acclimatization the preference changes when accompanied by attention and reference to acoustic instrument sounds and voices."
I forgot about the nulls to the sides, certainly an advantage.
Don't really agree with Linkwitz regarding reference to acoustic instruments and voices, I mean everything is recorded which will change the sound so a live piano and a recorded one won't be the same - an illusion of a real instrument sound is the best we can hope for - IMO anyway.
I don't listen to classical music so that's not so relevant to me anyway. My thinking has always been that the recordings are not made using open baffle or planar speaker, so to get the closest needs a box speaker. But I suppose that given all the other variables involved, that's really just a conceit :)
Halfway Tree
31-10-2024, 21:03
I forgot about the nulls to the sides, certainly an advantage.
Don't really agree with Linkwitz regarding reference to acoustic instruments and voices, I mean everything is recorded which will change the sound so a live piano and a recorded one won't be the same - an illusion of a real instrument sound is the best we can hope for - IMO anyway.
I don't listen to classical music so that's not so relevant to me anyway. My thinking has always been that the recordings are not made using open baffle or planar speaker, so to get the closest needs a box speaker. But I suppose that given all the other variables involved, that's really just a conceit :)
I always presumed Linkwitz was talking about recorded acoustic instruments and voices, but could be wrong. Yes, I agree it's all an illusion anyway.
The argument that recording studios don't use dipoles for monitoring recording is quite correct, but I'd also argue that a box reproduces more of your room signature and that a dipole which generates fewer room modes has less of a room signature with the big provisio that the backwave has to have the same tonality as what is coming from the front of the speaker.
The only dipoles I know of in use in the recording industry is mastering engineer Barry Diament using Magneplanar 3.6Rs (all the original Island Bob Marley remasters, beautiful recordings with DR of 12-16) and Jack Vad, the producer and engineer at the San Francisco Symphony using LX521s for the final mixdown to ensure correct instrument placing in the soundstage and tonality.
But at the end of the day we can only guess at what the artist intended and use whatever suits us best.
Tony Faulkner of Green Room Studios uses dipole speakers (professional version of Quad 63 electrostatics) for monitoring, and has done for a couple of decades.
I always presumed Linkwitz was talking about recorded acoustic instruments and voices, but could be wrong.
Maybe he does. Simple rule - if you don't agree with Linkwitz you either misunderstood him or you're wrong.
Halfway Tree
12-12-2024, 22:46
Maybe he does. Simple rule - if you don't agree with Linkwitz you either misunderstood him or you're wrong.
With all respect I don't think you get to make the rules regarding Linkwitz, Martin. ;)
Ali Tait
13-12-2024, 11:22
Think that's kinda what Martin was saying? :D
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