Hi!
First post.. Sorry if my english is a bit rusty..
After selling my beloved hifi when kids started popping up (about 10 years ago)
I´ve recently started to get the bug again.. I have modified my speakers to the point of being unrecognizable (they started life as a pair of these: http://www.audiopro.se/sites/audiopro.se/files/expired_product_folders/Image44_produktinfo.pdf
a quarterwave pipe, but now they are 45cm tall closed cabinets with upgraded, hardwired crossover, extensive damping etc) and they start to sound pretty good with nice dynamics, a healthy dose of clarity but, of course, limited bass.
For that reason I built a pair of 8", 45L subwoofers with Peerless SLS 8 tuned to 27Hz. They hit a clean 20Hz in my room and sound amazing.. Tight, melodic bass with more power than I will ever need.
The unexpected quality of the subs has got me thinking about a simple but good sounding pair of main speakers to replace my Image 44 (where I believe the drivers have reached their maximum potential) and since I am a sucker for a big (larger than life, even..) soundstage I`m leaning toward an open baffle build..
My problem is that I don´t know anything about them.
How do I calculate the frequency response of an open baffle? In my box simulation software, can I simply use a closed box and make it extremly large?
What about phase cut-outs? If we play with a baffle of 100x80cm, do I still need to consider baffle step?
With my subs I won´t need extension below 120Hz -3dB and I hope that will make the whole thing a whole lot easier but since I´ve never played around with open baffles the theory is an unknown and I hope someone here will enlighten me.
I would also be very grateful for examples of drivers (even fullrange since I don´t hear anything above 15kHz anyway) that might work or builds that will inspire. I´ve done my searches but most discussions (when it comes to OB) seem to be about the problem of bass extension but that is of no concern to me.
Please, anything you have to give regarding the highs and lows of OB will be of interest to me.
First post.. Sorry if my english is a bit rusty..
After selling my beloved hifi when kids started popping up (about 10 years ago)
I´ve recently started to get the bug again.. I have modified my speakers to the point of being unrecognizable (they started life as a pair of these: http://www.audiopro.se/sites/audiopro.se/files/expired_product_folders/Image44_produktinfo.pdf
a quarterwave pipe, but now they are 45cm tall closed cabinets with upgraded, hardwired crossover, extensive damping etc) and they start to sound pretty good with nice dynamics, a healthy dose of clarity but, of course, limited bass.
For that reason I built a pair of 8", 45L subwoofers with Peerless SLS 8 tuned to 27Hz. They hit a clean 20Hz in my room and sound amazing.. Tight, melodic bass with more power than I will ever need.
The unexpected quality of the subs has got me thinking about a simple but good sounding pair of main speakers to replace my Image 44 (where I believe the drivers have reached their maximum potential) and since I am a sucker for a big (larger than life, even..) soundstage I`m leaning toward an open baffle build..
My problem is that I don´t know anything about them.
How do I calculate the frequency response of an open baffle? In my box simulation software, can I simply use a closed box and make it extremly large?
What about phase cut-outs? If we play with a baffle of 100x80cm, do I still need to consider baffle step?
With my subs I won´t need extension below 120Hz -3dB and I hope that will make the whole thing a whole lot easier but since I´ve never played around with open baffles the theory is an unknown and I hope someone here will enlighten me.
I would also be very grateful for examples of drivers (even fullrange since I don´t hear anything above 15kHz anyway) that might work or builds that will inspire. I´ve done my searches but most discussions (when it comes to OB) seem to be about the problem of bass extension but that is of no concern to me.
Please, anything you have to give regarding the highs and lows of OB will be of interest to me.
If you want that and a nice front row seat then you need an omni (i.e. less directionality), not an OB, which, if implemented as a real dipole, has more directionality.
A big (8"-10") midrange cone properly implemented will allow for a big soundstage.
Something like the TB 1808 would fit the bill (and the raising highs shouldnt bother the OP since he has reduced hearing at HF). Not the cheapest, but a simple option requiring minimal/no XO.
Also Visaton B200 (more dynamic in the lower midrange) can go without tweeter in his case, it rolls off around 12k.
Something like the TB 1808 would fit the bill (and the raising highs shouldnt bother the OP since he has reduced hearing at HF). Not the cheapest, but a simple option requiring minimal/no XO.
Also Visaton B200 (more dynamic in the lower midrange) can go without tweeter in his case, it rolls off around 12k.
Actually, I meant to say: "larger than life" happens very rarely and mainly depends on the recording technique.
15kHz cannot accurately be got from 12" nor 10" and not even 8" drivers.
Maybe a very good 6" might give accurate reproduction to 15kHz.
A 6" driver that is good to 15kHz will probably not have much in the way of Xmax. That will limit the SPL available at 120Hz.
These limits may force you to using a crossed over pair for good 120Hz to 15kHz reproduction.
Open baffle is different from infinite baffle, different from closed box, different from tuned box.
Roll off of open baffle is determined by the difference in path length from the front direct to listener cf. the back around the baffle edge then to the listener. This path length difference will always be applicable irrespective of the SPL. The width of the baffle determines the path length difference. Don't make the baffle circular (equal driver to edge distances). Probably not good square either. Maybe at least 50% longer than width/height. I don't think it matters whether it is laid out across the floor or standing up.
Maybe a very good 6" might give accurate reproduction to 15kHz.
A 6" driver that is good to 15kHz will probably not have much in the way of Xmax. That will limit the SPL available at 120Hz.
These limits may force you to using a crossed over pair for good 120Hz to 15kHz reproduction.
Open baffle is different from infinite baffle, different from closed box, different from tuned box.
Roll off of open baffle is determined by the difference in path length from the front direct to listener cf. the back around the baffle edge then to the listener. This path length difference will always be applicable irrespective of the SPL. The width of the baffle determines the path length difference. Don't make the baffle circular (equal driver to edge distances). Probably not good square either. Maybe at least 50% longer than width/height. I don't think it matters whether it is laid out across the floor or standing up.
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Just planted some numbers into Win Calc.
120Hz has a wavelength of ~2.8m
If the path length difference were 1.4m, then the back wave would be exactly half a wavelength different from the front path. = complete cancellation of the 120Hz when baffle ~2.6m wide. 120Hz requires a very big baffle.
Are my numbers and understanding correct?
120Hz has a wavelength of ~2.8m
If the path length difference were 1.4m, then the back wave would be exactly half a wavelength different from the front path. = complete cancellation of the 120Hz when baffle ~2.6m wide. 120Hz requires a very big baffle.
Are my numbers and understanding correct?
Thanks for your replies.
First of all: "larger than life" is just poor english. What I meant was that I want a soundstage that expands beyond the width of the speakers and deep into the back wall (when the recording permits it), and that feeling of music that seems to originate in thin air rather than from the speaker cabinets. The speakers I use now sound clean, fast and detailed but the sounds stays in between the speakers and they seem to project the sound forwards rather than all around. There is a sense of depth but only in the dead center. The more to the side a deep laying sound is located, the more to the front the sound seems to originate from. Hard to explain this..
I must have misunderstood something. I assumed that an OB that radiates as much backwards as forwards would give a big, airy soundstage and not that they are in fact MORE directional than conventional designs (as written by 6.283).
"AndrewT"
If the baffle needs to bigger than 100x75 (much bigger?) I guess I´m screwed.. I´m married, and I know that it would take quite a struggle to get acceptance even for my original 100x75cm plan.. Also, the technical know-how needed to make an OB work seems to be some way past me.. I guess I´ll have to go the safer route and try to come up with a more conventional speaker to suit my needs. 120Hz is an easy task for most drivers (in a box, that is) and even though I like some midbass impact, which rules out the 3-3.5" drivers so many rave about in the fullrange section, a typical 5" would hit 120Hz in very small volumes. I guess the guys that say "learn to crawl before you walk" really know what they are talking about.. I´ll put the OB-plan on ice for now.
First of all: "larger than life" is just poor english. What I meant was that I want a soundstage that expands beyond the width of the speakers and deep into the back wall (when the recording permits it), and that feeling of music that seems to originate in thin air rather than from the speaker cabinets. The speakers I use now sound clean, fast and detailed but the sounds stays in between the speakers and they seem to project the sound forwards rather than all around. There is a sense of depth but only in the dead center. The more to the side a deep laying sound is located, the more to the front the sound seems to originate from. Hard to explain this..
I must have misunderstood something. I assumed that an OB that radiates as much backwards as forwards would give a big, airy soundstage and not that they are in fact MORE directional than conventional designs (as written by 6.283).
"AndrewT"
If the baffle needs to bigger than 100x75 (much bigger?) I guess I´m screwed.. I´m married, and I know that it would take quite a struggle to get acceptance even for my original 100x75cm plan.. Also, the technical know-how needed to make an OB work seems to be some way past me.. I guess I´ll have to go the safer route and try to come up with a more conventional speaker to suit my needs. 120Hz is an easy task for most drivers (in a box, that is) and even though I like some midbass impact, which rules out the 3-3.5" drivers so many rave about in the fullrange section, a typical 5" would hit 120Hz in very small volumes. I guess the guys that say "learn to crawl before you walk" really know what they are talking about.. I´ll put the OB-plan on ice for now.
Look for a pair of Magnepan MG-1 or MMG to match with your subs. They may not be exactly what you want but it will be very good and you'll learn a lot from listening to those panels.Much is not understood about open baffle... I've heard extension to below 40hz with some large panels that had no baffle. Proximity, EQ and room have large effects. As a pro bass player I love the sound of open drivers especially panels... very clean, bass... may sound lean to some but if your goal is club sound then JBL's in ported boxes is better road.
"bassnkeys"
A pair of MG-1:s is hard to find here in Sweden..and I´m on a pretty tight budget. My hobby is accepted for now, but I cant let it become expensive.. Magnetostats and electrostats have a sound I like, but they are costly and usually need some serious driving and power-amps is no option. I use a semi-old Denon 4306 and it will have to do for now. I also like the idea of having something that I´ve built myself. With the subs it would mean a completely homemade package..
I´ve built qiute a few speakers in my day, using drivers from Morel, SS and Seas and some turned out really nice. I have kept my ProAc-clones but never really liked the way they sound.. Maybe the drivers can be used to better effect ( SS-8546/D2010 )?
Anyway, I was appealed by the unusual principal of OB and, I must confess, the simplicity of the build in practical terms. Just a slab of wood and something to support it.. I still have all the tools for electrical work but I dont even have a place to start cutting wood and to have boxes made by a carpenter is pretty expensive here. I guess I´ll have to figure it out, though.
A pair of MG-1:s is hard to find here in Sweden..and I´m on a pretty tight budget. My hobby is accepted for now, but I cant let it become expensive.. Magnetostats and electrostats have a sound I like, but they are costly and usually need some serious driving and power-amps is no option. I use a semi-old Denon 4306 and it will have to do for now. I also like the idea of having something that I´ve built myself. With the subs it would mean a completely homemade package..
I´ve built qiute a few speakers in my day, using drivers from Morel, SS and Seas and some turned out really nice. I have kept my ProAc-clones but never really liked the way they sound.. Maybe the drivers can be used to better effect ( SS-8546/D2010 )?
Anyway, I was appealed by the unusual principal of OB and, I must confess, the simplicity of the build in practical terms. Just a slab of wood and something to support it.. I still have all the tools for electrical work but I dont even have a place to start cutting wood and to have boxes made by a carpenter is pretty expensive here. I guess I´ll have to figure it out, though.
Sweet Depth and Spaciousness
I would try ribbons. Many ribbons are available at reasonable prices. Vertical ribbons launch a columnar sound wave that is very controlled phase-wise. Maybe match a B&G 8" ribbon (open) with a nice mid driver you could then meld with your sub. Keep the sweet bass you have and then add that image/depth you dig. I have never heard anything that produces depth, width and image like an open ribbon!
I would try ribbons. Many ribbons are available at reasonable prices. Vertical ribbons launch a columnar sound wave that is very controlled phase-wise. Maybe match a B&G 8" ribbon (open) with a nice mid driver you could then meld with your sub. Keep the sweet bass you have and then add that image/depth you dig. I have never heard anything that produces depth, width and image like an open ribbon!
I will give my usual recommendation for info on speaker design, particularly OB theory & design:
Quarter Wavelength Loudspeaker Design
I built a variation on MJK's small, passive OB using Fostex FF85k and Eminence Alpha 15A. I think the result is outstanding for the money.
Cheers, Jim
Quarter Wavelength Loudspeaker Design
I built a variation on MJK's small, passive OB using Fostex FF85k and Eminence Alpha 15A. I think the result is outstanding for the money.
Cheers, Jim
Shylock,
You need to give us a little bit of more info on your requirements:
Room, placement, budget, active/passive etc...
How do you place your subs?
Do you plan to have your OBs sit on your subs?
If you plan to place subs and mains separately, than you probably need to aim at a crossover point of 80Hz or lower.
Here is an option for a floorstander OB:
http://www.quarter-wave.com/OBs/OB_Design.pdf
And here is something that could stand on top of your subs:
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-46.html#post2752617
You need to give us a little bit of more info on your requirements:
Room, placement, budget, active/passive etc...
How do you place your subs?
Do you plan to have your OBs sit on your subs?
If you plan to place subs and mains separately, than you probably need to aim at a crossover point of 80Hz or lower.
Here is an option for a floorstander OB:
http://www.quarter-wave.com/OBs/OB_Design.pdf
And here is something that could stand on top of your subs:
http://www.diyaudio.com/forums/multi-way/110583-fast-fun-inexpensive-ob-project-46.html#post2752617
Dude, I think you're giving up way too easily. Have you considered a hybrid OB design? OB mids but with the LF's in an enclosure. You just might find that this will give you the imaging you're after while getting low enough without using a baffle half a meter wide.
Something like this https://sites.google.com/site/undefinition/diy-sunflowers might work for you sealed, tho it still goes lower than you need.
Or, you say that you've already built a number of speakers so maybe you're already past the "crawling" stage and can/want to build something on your own. Altho if you don't yet have measurement gear or facility with the various free design programs available then that's actually a pretty dangerous suggestion.
Personally I have been wanting to use one of these BG's as an OB mid
http://gr-
research.com/neo8.aspx
Bohlender Graebener Neo8-PDR Planar Transducer 264-713
Bohlender Graebener Neo10 Planar Transducer 264-715
with the corresponding OB tweeter
Neo 3
probably with the addition of sides or side 'wings' tho to push the mid F3 point as low as possible. Lots of choices for a woofer, tho I was thinking to keep the baffle narrow enough to put the XO point = the baffle step frequency = the mid F3 point. Something similar to this, Philharmonic Audio but OB except for the woofer.
Of course, I don't know what your budget is nor if it's best for you to stick to a proven design, but I just wanted to say don't give up yet.
Cheers
Hi Shylock,
the width of the stage is created by lateral reflections. If you take a real dipole then there are nulls to the side and sound is 6dB down at 60°. That creates only some not so strong reflections. An OB with a dipolar (dipole like) response has also nulls to the side but more radiation <90°. And that amount, which is not constant, depends on the driver, Frequency and baffle width.
However, when I read your description I can't help myself but thinking that you really want an omnipolar design with strong reflections all around. I have both so I know the differences.
If you are interested, look at my home page (see signature). There you find an omni design (Demokrit) with hopefully useful descriptions what it does in a room.
the width of the stage is created by lateral reflections. If you take a real dipole then there are nulls to the side and sound is 6dB down at 60°. That creates only some not so strong reflections. An OB with a dipolar (dipole like) response has also nulls to the side but more radiation <90°. And that amount, which is not constant, depends on the driver, Frequency and baffle width.
However, when I read your description I can't help myself but thinking that you really want an omnipolar design with strong reflections all around. I have both so I know the differences.
If you are interested, look at my home page (see signature). There you find an omni design (Demokrit) with hopefully useful descriptions what it does in a room.
Hi,
Having stereo subs is a very good starting point, so it is do-able.
The Sunflower Redux is as good as anything else to look at, for something
similar you need to run your subs quite a lot higher than 120Hz, but do-able.
Quarter Wavelength Loudspeaker Design
Linkwitz Lab - Loudspeaker Design
Music and Design (look at the NaO mini)
rgds, sreten.
Having stereo subs is a very good starting point, so it is do-able.
The Sunflower Redux is as good as anything else to look at, for something
similar you need to run your subs quite a lot higher than 120Hz, but do-able.
Quarter Wavelength Loudspeaker Design
Linkwitz Lab - Loudspeaker Design
Music and Design (look at the NaO mini)
rgds, sreten.
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I argue the same Andrew. A baffle of that width you calculated isn't required for the OP needs.
A simple 2-way OB design (mains) would work great here ... and I think the subs could be crossed at 120hz too. The right 12" driver mounted on a simple baffle with a couple 4-5" deep wings would reach 120hz no problem. The right 12" driver would be able to cross over to the right tweeter around 15-1800hz. Don't be scared to try this.
A simple 2-way OB design (mains) would work great here ... and I think the subs could be crossed at 120hz too. The right 12" driver mounted on a simple baffle with a couple 4-5" deep wings would reach 120hz no problem. The right 12" driver would be able to cross over to the right tweeter around 15-1800hz. Don't be scared to try this.
Simple answer: Get yourself a pair of the really excellent Seas Prestige FA22RCZ fullrange drivers. Put them on your 75x100 panel, or even smaller. Offset them from center. On a small baffle they will work down to 120Hz easy, and because of the rear radiation, will give you that open sound you crave. In a normal size room, they will be pretty darn flat at the listening position (I have measurements to back that up).
That will be an excellent start. If you want to push it farther, you will have the basic material in hand.
That will be an excellent start. If you want to push it farther, you will have the basic material in hand.
I realize that I have not given enough info..
My room is 4x7 m with the speakers on one of the short walls and my listening position about 4m from the speaker wall. On the wall behind the listening position I have a bookshelf covering the entire wall (with books), the floors are covered (mostly) with carpets, lots of paintings on the walls and all in all the room works well when it comes to acoustics. The subs measure HxWxD 600x250x400mm and originally I used them as stands for my main speakers. I have experimented a lot with placement, and they work well in most places (having 2 of them makes placement qiute a bit easier..) but currently they sit in the front corners of the room facing downwards with about 60mm between the driver and the floor. I use a 400w plate subwoofer amp to drive them and it seems to cope well. Signal comes from the sub pre out on my Denon 4306 and I would have preferred to use the main pre out (my plate amp has an adjustable but non bypassable low-pass filter) to avoid using 2 filters on top of each other but since I must set my front speakers as "small" and cut them at 120Hz (I use 100 and 120.. I have not decided which I prefer yet) the main pre out also gets cut at that frequency rendering it useless to feed the sub amp. I have not noticed that the filter on filter-thing causes any harm.
Budget.. Well, you might laugh but it´s really tiny. In USD i guess it would equal around 500$..and drivers are more expensive in sweden than in the US and ordering from the states would mean a hefty shipping bill..
"bassnkeys"
I agree! Ribbons are great. A friend went overseas for 3 months about a year ago and I borrowed his speakers while he was away. A standmount called Transmission Audio M1i which uses a 5" tweaked Jordan and a Ribbon tweeter mounted in what could be called an OB. Man.. They sound incredible and even though it was nice to see my friend again when he returned I didn´t like the fact that his speakers had to leave.. Used prices here in sweden is in the 1500$-range but if I had the money I would definitly consider them. They are a bit overkill though, with bass extending down in the mid 30s. Now I have the subs, and it would be pointless to have something that capable in the bass.
I´m not that keen on bying something finished either. My wish is to have a homemade speaker system. I have no experience with ribbons so if I were to build something with them I would probably need to copy someone elses design. That´s ok, though. I want it to be built by me, not necessarily designed by me.
I looked at some of the links and I spent some time last night studying the theory of OB:s.. Not much wiser as of yet, but Rome was not built in one day..
The "Fast, fun, Inexpensive" OB seems nice.. The Vifa TG9 is cheap and I´ve heard it sound amazing in a 4L BR so that is a driver I would very much like to use. I guess it needs to be crossed over a fair bit higher than my maximum of 160Hz (as I said there´s a non bypassable low-pass filter in my plate amp and 160Hz is it´s maximum setting..) in an OB.. If it could be made to work though, it would be an eye-brow raiser.. A small 3.5" in a big slab of wood making beautiful noises..and for next to no money. A TG9 costs about 20 bucks here..
I would happily accept design suggestions. I guess there are lots of builds ready to be copied on the net, if one knew where to look.
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