it is one thing designing something for yourself diy, quite another to get it built to repeatable commercial standards and promoted to make a sensible profit for both manufacturer and retailer.
Nothing sinister in that.
OB's have virtually zero commercial appeal. It is good to see the Jamo exists at all.
Nothing sinister in that.
OB's have virtually zero commercial appeal. It is good to see the Jamo exists at all.
No, I have not tried these particular drivers but they are on my list of candidates. I did some simulations and was impressed with them assuming the T/S parameters are correct. From my experience with the 18" Goldwood woofers I think these would work well.
If you are going the route of one or two large diameter high Qts drivers I am not sure 30 to 1 kHz is such a good idea. You need to address the dipole hump in some way, I use it to set the crossover locations and filter types.
A cheap and easy to build dipole system is simple to design and implement if you do the engineering and carefully pick the drivers. Low cost does not mean low sound quality, it is amazing how good a simple cheap OB system can perform.
I have. 2 per side with a 10" midrange. Very nice. Can actually play down to 16Hz on the right baffle.
I have two dipole systems in my room, one has a flatter bass response and the other a tapered bass response. In my room the flatter bass design sound better. But as you say it is room dependent which would work best
I think you are on the right track. I have many dual woofer OB systems modeled using a ~20" wide baffle that is between 38" and 42" tall and the geometry works simlar to the one in the article. If you look at the pdfs of the OB MathCad worksheets on my site you will see some examples of an active and a passive system.
After hearing them recently I would say that they do. But thats just my opinion.
I understand with the goal, and very agree with that but I'm going to add some ideas.
Not so simple to make. OBs in the passive way are hard to do. Definitively not for beginners.
I'm agree simple made and big sound but to do it, a lot of work should be done. I am not agree to make it absolutely simple, it is a mistake i think, because you can ignore a lot of things to make it optimized and don't get the best from the setup.
On the paper it will difficult to have an opinion how it will sound.
Some of us have enough experience or have tested to say it is/could be good or not. The problem is harder because you want it cheap. How many drivers to test before to find the good one ?
Good news the GRS 15 seems to be a good finalist for 30 $
In Europe we don't have the chance to find such low cost drivers
Cheers.
Not so simple to make. OBs in the passive way are hard to do. Definitively not for beginners.
I'm agree simple made and big sound but to do it, a lot of work should be done. I am not agree to make it absolutely simple, it is a mistake i think, because you can ignore a lot of things to make it optimized and don't get the best from the setup.
On the paper it will difficult to have an opinion how it will sound.
Some of us have enough experience or have tested to say it is/could be good or not. The problem is harder because you want it cheap. How many drivers to test before to find the good one ?
Good news the GRS 15 seems to be a good finalist for 30 $
In Europe we don't have the chance to find such low cost drivers
Cheers.
I cannot agree. In my opinion, and in my experience, an OB speaker can be dead easy to build and get great sound from a minimal investment in parts and time. I have layed out a recipe for doing this that has worked for me and many others over the past couple of years. There are other recipes available if you look around.
Buying the right woofer eliminates the need to design a box, a big design simplification. Getting a midrange and tweeter, or a full range driver, to match the woofer can be done by running a few simulations. Designing a crossover is no more difficult then any box speaker design, you can even use some of the same free tools from the Internet to do the calculations. Sizing a baffle is not too tough and again some simulation work will help place the crossover frequencies to take advantage of or mitigate the dipole hump. It is that easy. The speakers sreten originally referenced are really very simple designs/concepts that match my recipe. Reviews have been positive so something must be going right. So I conclude that with a few hundred dollars you can build a very good OB speaker system if you keep it simple.
There are many more complicated design methods/philosophys that have very vocal proponents. Complex baffles with active crossovers and multiple amps that meet very strict design goals for polar response. More money invested, more chances of screwing up. People like a challenge and I am sure they are rewarded for their efforts. But I have to wonder where the point of diminishing returns sets in for the added complexity, in audio small differences (maybe improvements) are often blown up to be night and day dramatic advances.
If you want low cost, a simple design, good performance, then it is easily available now so jump in and build and OB system. If you want to agonize, sweat every detail, and shoot for every 0.1 dB of polar response then there are also options available following that path. What is good enough only you can decide. There is no perfect OB design.
Martin
This happens to me A LOT.
I've found that I get the best ideas drinking Guiness. Budweiser produces the worst ones.
>>> So I conclude that with a few hundred dollars you can build a very good OB speaker system if you keep it simple.
I agree with MJK on this. Attached is a pic of my son's speakers. Wood from home depot, inexpensive drivers connected to an inexpensive T-amp. Source is his laptop. I do use a powered sub amp to power the PE buyout Jamo 15" woofers to dial in the bass. The main driver is the Pioneer B20 topped with a cheap piezo (I think it cost 95 cents bc i bought a box of 10). I've had more expensive Betsys and much more expensive TBs on this baffle and while the sound changes, without knowing the prices, some have preferred the least expensive option. I even tried a $7 ceiling speaker and it sounded wonderful.
If you have space, OB offers a seductive alternative to much more expensive, complicated, boxed speakers that simply don't produce as large and spacious a listening experience. I really have a difficult time thinking of new speaker projects and designs that offer best possible sound without considering OB seriously.
The reason I mentioned the Jamo drivers is because the beautiful OB sreten referenced is a Jamo product (tho the woofers are different). The PE buyouts were $20 and work well (qts was .85... not perfect but close enough and it all works great). They actually seem better built than the Alpha 15s I use in H-frames (another mind blowingly simple design that produces mega bass for relatively cheap... and they double as speaker stands). These 15" woofers radiate bass more effortlessly than any 8, 10 or even 12" powered sub driver (and i have all three) i've ever heard and the 15" GRS and Goldwood woofers appear to be similar in design enough that i'd expect similar results (tho different since their specs are not exact). I just can't imagine a 15" woofer with a qts between 1 and 2 producing anything less than great bass on a simple OB.
Also, looking at the Zapf link sreten shares, it's fun to see all the box designs with different ports and driver configurations. Simply putting these components onto an appropriately sized OB along with helper woofers (and tying it all together with proper xover components) should easily out perform anything on that link.
Boxes speakers have their own set of advantages (mostly that they can be easily placed on a shelf or easily tucked away in a room conveniently) but they are all compromised designs... just like an OB (which requires more space but rewards with better sound IMHO).
Based on my sims, if you can tolerate an 18" x 38" (or larger) OB in your room you can take advantage of what relatively inexpensive 15" high qts woofers can do and enjoy them along with your choice of wonderful sounding drivers (both full range and xover types).
Zilla
I agree with MJK on this. Attached is a pic of my son's speakers. Wood from home depot, inexpensive drivers connected to an inexpensive T-amp. Source is his laptop. I do use a powered sub amp to power the PE buyout Jamo 15" woofers to dial in the bass. The main driver is the Pioneer B20 topped with a cheap piezo (I think it cost 95 cents bc i bought a box of 10). I've had more expensive Betsys and much more expensive TBs on this baffle and while the sound changes, without knowing the prices, some have preferred the least expensive option. I even tried a $7 ceiling speaker and it sounded wonderful.
If you have space, OB offers a seductive alternative to much more expensive, complicated, boxed speakers that simply don't produce as large and spacious a listening experience. I really have a difficult time thinking of new speaker projects and designs that offer best possible sound without considering OB seriously.
The reason I mentioned the Jamo drivers is because the beautiful OB sreten referenced is a Jamo product (tho the woofers are different). The PE buyouts were $20 and work well (qts was .85... not perfect but close enough and it all works great). They actually seem better built than the Alpha 15s I use in H-frames (another mind blowingly simple design that produces mega bass for relatively cheap... and they double as speaker stands). These 15" woofers radiate bass more effortlessly than any 8, 10 or even 12" powered sub driver (and i have all three) i've ever heard and the 15" GRS and Goldwood woofers appear to be similar in design enough that i'd expect similar results (tho different since their specs are not exact). I just can't imagine a 15" woofer with a qts between 1 and 2 producing anything less than great bass on a simple OB.
Also, looking at the Zapf link sreten shares, it's fun to see all the box designs with different ports and driver configurations. Simply putting these components onto an appropriately sized OB along with helper woofers (and tying it all together with proper xover components) should easily out perform anything on that link.
Boxes speakers have their own set of advantages (mostly that they can be easily placed on a shelf or easily tucked away in a room conveniently) but they are all compromised designs... just like an OB (which requires more space but rewards with better sound IMHO).
Based on my sims, if you can tolerate an 18" x 38" (or larger) OB in your room you can take advantage of what relatively inexpensive 15" high qts woofers can do and enjoy them along with your choice of wonderful sounding drivers (both full range and xover types).
Zilla
Attachments
That would be me
It all came into one design after I made very flexible goals and tried them on all OB types of enclosures. The best fit was with the OB winning against H and U frames.
One of my goals was this:
H frame and U frame were rejected due to their bump at medium-low frequencies (200-1000 Hz).
So I was left with the OB option. The requirement for at least 60hz to 1+ khz meant that all baffle step lies in the reproduced frequencies. The OB was meant as a midrange/HF part of a system capable of 20Hz to 20 kHz @ no less than -3 db, by goal it was meant to cover the frequencies from 60-100 hz and up... but see what happened...
Then I got 4 of these: HIFI KIT ELECTRONIC AB - Högtalarelement HiFi Hembio Billjud/Marin Studio PA/DJ Kablage Tillbehör
Designed a LR-2 crossover to a 3 inch TB fullrange at 1250 Hz with the Mathcad sheet and applied a transformer type variable BSC: http://www.diyaudio.com/forums/full-range/180491-l-here-l-there-l-everywhere.html - second page
Crossover:
Simulation:
Note that it is of the two 12 drivers and the fullrange only, the big bass cabinet is a dramatization only.
And it worked great:
The two lower boxes are used only as a stand.
Actually, I was prepared for much more fight... but after several simulations ran on the Mathcad and applying of the BSC to the bass drivers only, it turned out a standalone fullrange system with bass and very pleasant sound. About -8 or -9 db @30 hz with the BSC only and no EQ. Withstands at least 100W full range signal (Cms ~0.6mm/N, but Qms ~2.2-2.4 with Xmax of ~4mm)
The Gammas are Qts a little below 0.5, ~29 hz Fs prior to breaking in and 25-26 Hz after it.
Then the big bass cabinet came:
Which was useless to some degree, if I knew that the OB will be so capable in the lower frequencies, I would have bought 4 more "12 drivers and made pure OB's with 4 12's per side, probably the lower pair crossed over much lower.
But I like the system as it is, because it is scary like that
More info and simulations: Collection of Links of Components of My Future System
Best Regards!
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Yep, I agree with Martin and Zilla. You can get great sound out of an OB without much money or headaches. Where most people fail is the crossover - you have to think "out of the box" (sorry). A good OB crossover just isn't going to be the same as a box crossover with the same drivers.
There are the trade-offs that Zilla mentions, size and space. Add to that loss of efficiency - you have to make up for the open baffle bass loss if you want good tonal balance. But they are fun, fast to build and sound great. Ideal DIY material.
There are the trade-offs that Zilla mentions, size and space. Add to that loss of efficiency - you have to make up for the open baffle bass loss if you want good tonal balance. But they are fun, fast to build and sound great. Ideal DIY material.
That would be me
OK, I can accept your methods, design, and speaker's performance as being very good.
But if we go back to the original topic of the thread. Consider the person reading as having a receiver or integrated amp and a source (CD player, TT, or iPod) and they have $400 to spend excluding the wood for an OB speaker system. What other options exist?
Martin
Sreten, There seems to be a bit of confusion about what is meant here by simple.
I would argue that with relatively inexpensive drivers, but a LEAP/CALSOD/SE/LSPCAD (software equipped with optimizer) designed crossover, truly superb results may be achieved. The resulting x/over may be a bit more complex, but imho this pays off big dividend.
However this can only be done through the well know procedure of measuring the on-baffle drivers and importing the .FRD and .ZMA files into the software.
But then again, I am sure Sreten is well aware of all this.
Cheers,
Eelco
I would argue that with relatively inexpensive drivers, but a LEAP/CALSOD/SE/LSPCAD (software equipped with optimizer) designed crossover, truly superb results may be achieved. The resulting x/over may be a bit more complex, but imho this pays off big dividend.
However this can only be done through the well know procedure of measuring the on-baffle drivers and importing the .FRD and .ZMA files into the software.
But then again, I am sure Sreten is well aware of all this.
Cheers,
Eelco
I am a bit surprised when people say DIY speaker is easy ...
Yes you can put a driver in a box, on a panel, you will have a sound. It is the easiest thing. Make a good sound, sound really good is far from easy.
One thing more complicated are the ears, it took me a lot of year before having an enough good ear to say this good for me !
Audio is like taste, we should make it work to make it good ? no ?
We don't still talk about technical skills but decoding sound by ears...
Tools exist but how many time do we need to have a good level of using them ?
You must read the notice, learn how it work ! How many time do you need ?
Say it is easy to make low cost speaker is true but not for every one.
OB is more difficult I think but it's my opinion.
Remember Martin, Pano, Godzilla : How many years have you done Audio ?
More than 10 years I think, yes audio is easy after this time
To be very positive, because the discussion is too much serious
Yes we can have low dollars speaker which works great
Yes we do audio for our satisfaction
Yes you can put a driver in a box, on a panel, you will have a sound. It is the easiest thing. Make a good sound, sound really good is far from easy.
One thing more complicated are the ears, it took me a lot of year before having an enough good ear to say this good for me !
Audio is like taste, we should make it work to make it good ? no ?
We don't still talk about technical skills but decoding sound by ears...
Tools exist but how many time do we need to have a good level of using them ?
You must read the notice, learn how it work ! How many time do you need ?
Say it is easy to make low cost speaker is true but not for every one.
OB is more difficult I think but it's my opinion.
Remember Martin, Pano, Godzilla : How many years have you done Audio ?
More than 10 years I think, yes audio is easy after this time
To be very positive, because the discussion is too much serious
Yes we can have low dollars speaker which works great
Yes we do audio for our satisfaction
Well... I don't know
I spent a total of about 359.28$ on the OB part. This is drivers, crossover, BSC and wood. So it's within parameters.Honestly, I don't have a system that can outperform it regarding the acoustic capabilities. Only my Goldwood H frames + OB's... which use ribbon tweeters and cost 1000$ for the pair. (this is in Europe, in the states, it would have been half of that)
Maybe sealed enclosure 2way, but it doesn't come close in acoustic terms nor it does usually as bass extension and is more complex.
But that is why I make OB, they come cheap and with a great sound. Actually it is a little confusing for the people, since the easiest and most cost effective "enclosure" comes the closest to the best possible one, the in wall speakers (best according to Mr. E. J. Jordan) in terms of clarity and effortless acoustics. Even the biggest flaw of the OB's, the baffle step or H/U frame resonance peak can be used in the designs as an advantage for letting the midrange/HF unit have more headroom.
Thanks for your work Mr. King!
Edit: Jerome, Thanks to Mrtin, Pano, Godzilla and many other members here, a beginner like me was able to understand and build an OB design with great results. Haven't been the MJK's design I would never have such speakers and would never have gained entrance into the audio! That is completely serious! I was so fascinated by the knowledge sharing approach that I even made my own forum. The open baffle is the door to audio for beginners and is cheap too. I was with a pile of electronics at hand and a pair of awful Cerwin Vega's that sounded terrible. I have used some inept forum help and directions elsewhere and did spent twice the price of my OB+H frames with no useful result.
Then I found here and open baffles and this introduced to me a whole lot of science in a way that I was able to understand it and actually use the knowledge.
The funny part is that although it is an undoubtedly easy entrance into the real HiFi, it is one of the best options in principle. The part with the "Easy" is probably due to the fact that many variables are out of consideration. Compliance of the box, low crossover anomalies and many others. I even apply my OB knowledge to other systems. Strangely while OB knowledge is applicable to more complex systems, the opposite is not true. I can go on much more, but I have to stop if I want someone to read this sentence in the end.
Best Regards!
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Happy (US Turkey) Day,
By honing in on maximizing performance vs. cost this thread is focusing on the basic design concepts the open baffle speaker. Much of the conversation is theoretical.
I have built 3 versions of OB’s (for the fun) one out of the Linkwitz mold. The baffle had reinforcing plywood on edge screwed to the baffle and the drivers were mounted sandwich style, squeezed between two layers of closed cell neoprene.
This baffle is much more ridged than an unreinforced sheet of plywood. This approach to baffle construction and speaker mounting reduced the motion/vibration of the baffle as measured with my feigner tips. From my perception the sound produced by the resonance of the baffle is also much reduced.
Thoughts?
Do low cost construction methods belong in this thread?
DT
By honing in on maximizing performance vs. cost this thread is focusing on the basic design concepts the open baffle speaker. Much of the conversation is theoretical.
I have built 3 versions of OB’s (for the fun) one out of the Linkwitz mold. The baffle had reinforcing plywood on edge screwed to the baffle and the drivers were mounted sandwich style, squeezed between two layers of closed cell neoprene.
This baffle is much more ridged than an unreinforced sheet of plywood. This approach to baffle construction and speaker mounting reduced the motion/vibration of the baffle as measured with my feigner tips. From my perception the sound produced by the resonance of the baffle is also much reduced.
Thoughts?
Do low cost construction methods belong in this thread?
DT
Hi,
Simple in this case is the design work has been done for you.
The mid/treble c/o is as described for Zaph's in wall speaker.
The bass mid c/o if the offset one as described in
MJK's article but adapted for a 4 ohm bass section.
As stated in my original post, full-on modelling of the bass/mid
c/o may yield better alternatives, but MJK's offest c/o is going
to be near, and far better than any arbitrary c/o point/function.
So vertically 2x15" bass, 5" mid, 1" treble 20" wide, height to suit.
MJK may well be right the Goldwood 88dB Qts=1.95 drivers would work
even better than the GRS 87dB Qts=1.4 drivers, but as an engineer
I don't like paying more for something with a much smaller magnet.
the GRS unit @$23 for 4 or more is what makes the thing appeal.
I just think the better apparently built unit is going to be better.
It may not be perfect, but it will work, exceedingly well compared
to the Jamo's in the mid/treble, the bass end not so much so, but
I reckon it would be an interesting large speaker for not much, of
course not suited to some, but it is budget "exotica".
Senstivity is "only" 87dB, but this does mean decent bass without
recourse to the massive baflles you need for higher sensitivity.
rgds, sreten.
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