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Old 21st November 2012, 03:49 PM   #1
mortron is offline mortron  Canada
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Default First Open Baffles

So I have pestered and lurked for some time here, and yet to really start a project and share it with you all. This will be my first.

I had pondered a FAST setup for some time, and having come from a pair of Magnepan MG1c to Dynaco a25 put my tastes into perspective. I like the airy open sound, but I'm a cone guy. Must be the bass player in me.

When researching drivers I came across at least 5 or so tempting designs that have been used to some success. I figured I would use a tried and tried method (more on this later). I came across a pair of older Visaton B200 with a pair of Dave's (planet10hifi) phase plugs for sale used for less than a C note, and got my butt in the car. Great visit with a cool guy (he had this switchable passive crossover in front of his seat to tweak to taste/material) who was running the Visatons in a large ported enclosure. Based on reviews and hearing them in a less than suitable enclosure ever so briefly, I paid the man his scratch and set out to do homework...

... I delayed the homework and recalled a cabinet maker friend who had saved some poplar 3/4" ply from the landfill at a job he was on. Managed to have enough wood to build the Dan Mason Dark Star open baffles also found on:

Wild Burro Audio Labs - Fullrange Speaker Projects - Basic Open Baffle Design

We made a few concessions due to size and I had to talk my friend out of putting too much time in on his only day off. He was throwing options at me like flush mount and I was getting stumped... I settled for a chamfer on the back edge and the drivers front surface mounted. BUT! we debated driver height. My friend is also a Magnepan user who like me, enjoys a tall soundstage and me, being 6'3 wanted a bit more height. We settled on 34" driver centre (knowing the bass would be less) they centre about an inch or two below ear level for me while seated... Unless I slouch

So final baffle dimensions were out of one 17-3/4" by 84" and one 17-1/2" by 96" sheet... Roughly. So we made the outside wings 17-3/4"x42" and ripped the other board into 10 and 7-1/2" strips both 48" high.... Pretty close to design. I am running my phono rig into a Bottlehead Quickie Tube Preamp and Denon POA 2400a power amp. Filling out low end is a Paradigm PDR10 subwoofer (if you call it a subwoofer) crossed at 150hz (the highest).

Firstly I will say, the hinged wings make trying to understand open baffle dynamics very exciting. I have heard these drivers referred to as shouty, and was given a schematic for a notch filter (i believe its a notch), but am not really sure if they would be regarded as shouty. We shall see how others hear them. I flapped them around a bit and my audiophile buddy and my drinking buddy both raised their eyebrows a bit when they saw how it shifted sound. Strings, jazz and vocals are just beautiful on these. Great soundstage. I was listening to a lot of first albums I hadn't heard before, but a quick spin of Dire Straits Brothers In Arms was able to confirm things were looking good. Toms on drum tracks sound very accurate and fully enjoyed some fIREHOSE last night. These things even handled Slayers Reign in Blood, although a few beers make Slayer sound good on anything. Sonny Rollins a Night at the Village Vanguard should be renamed, Sonny Rollins a night in Mort's Basement, because there was a very natural sound that filled out the room.

Due to the shape of the baffles I was able to experiment some and flip the babbles over and get a funky tilt due to the lower edge of the one wing. Bass response changed but it was like listening to kick panels from the back seat of a car with no front seats (Probably how Shaq would feel if his massive feet allowed space for them). I liked the height. I wish my sub crossed higher, as I feel there is a small gap in the bass. Because on my room layout and an imaging issue, I listen on the long wall. This presents a new scenario... I have no wall behind the speakers now. I do, but it's just a curtain, and beyond that is about 12 ft alcoves, three of them, the centre has a sloped ending. The curtain is heavier and does a nice job of breaking up and absorbing some sound, and opening them changes the sound some too.

Several design options and ideas have surfaced. One is to reinforce the back of the panels, and add a woofer to the outside wings and actively crossover them using miniDSP or something similar like Behringer DCX2496. I would like to Biamp and passively crossover, but the ability to design one straight off and feasibly is unlikely to produce the kind of results and abilities of active. I have only the one power amp, so I will take some time looking around, but for woofers I have read that the Eminence Beta 15 is more articulate than the Alpha 15 and using eq, the Qts value is of less concern. Another option is the H frame Goldwood 1858, but am not sure if I want to make new baffles yet, or if they will be as detailed as the Eminence Beta 15. then again I hear the AE IB 15 is amazing, and if one should ever become available used or cheap, that may be my choice.

We also pondered cutting off the baffles and lowering the two inside panels so the tops are at 42", flush with side wings to enhance some bass, and then thought of possibly tacking the rest on top to keep the 48" height. Also, i have yet to add the weatherstripping to the back of the driver. I am so new to this... Experimenting is very fun. Any helpful tips and or criticisms are welcome. I would like to thank the people I have been corresponding for their help on this, they know who they are

All in I have just under $100 into this, and I'm looking forward to living with these for some time.

Last edited by mortron; 21st November 2012 at 04:07 PM.
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Old 21st November 2012, 03:51 PM   #2
mortron is offline mortron  Canada
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Having trouble adding iPad photos... had to upload on my phone. Sorry
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Old 21st November 2012, 07:30 PM   #3
Nanook is offline Nanook  Canada
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Default nice first OB project.

Once you experience an OB it is pretty tough going back (but you've gotta have the room for them). I've built a modified version of the "JE Labs" OBs (which Joseph credits to the Japanese "Stereo Sound" magazine). I don't have the room to use them (they are 31.5" (H) X 35.5" (W)), but when I have used them daily they never failed to impress. These are the best sounding loudspeakers that I have ever had in my home but they dominate the room and are not "pet friendly". Oxford J10 fullrange drivers (as used in Fender tweed "Princeton" guitar amps of the late 50's and early 60's) and a salvaged pair of Mission branded 1" dome tweeters mounted coaxially. The crossover is handled by a salvaged pair from an original pair of Wharfedale Denton IIs. They also need a fair bit of good power (a Yamaha B-2 V-FET amp was used previously), and 3' behind them. An interesting note: the Wharfedale SFB-3s and the original Quad ESLs have a very similar dimension (look on JE Labs archive: open baffles page for further information and the comparison between the two).

Making a FAST might actually be better yet, particularly if you like the Dynaco A25 loudspeakers (I have a pair and love them too). The issue with bass and OBs is not lack of bass, but lack of visceral impact of the bass. I designed a set of OB/boxed subwoofer speakers (at the time I didn't know the term FAST) starting with 2X175 watt plate amps, 2X12" down-firing subwoofers and 3ft^3 enclosures for each. These are capable of bass in the 30Hz range and can easily over power a room, so some care must be taken adjusting the subs, and the floor must be very solid underfoot. I think under $500 did it for the two subs. The full rangers used in the panels were Altec 408-Bs followed by a pair of Jordan's JX92s. My audio partner has these and I can attest to the prodigious amount of bass available.

Dave (planet10) has a great amount of knowledge and one would do well to build one of his systems using his modified drivers. Pretty much any of his modified drivers are at least on par with the Jordans (at a considerably lower cost), even the least expensive ones. (look at planet10-hifi for further information). Dave's not the only game in town for fullrangers, but very good at very reasonable prices and well supported with good designs.

caveat: I consider Dave a friend, but my suggestion is based on my personal experience with his products. I have no financial or otherwise gainfull affiliation with him or any that make up planert10-hifi.
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Old 21st November 2012, 08:24 PM   #4
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NoBox BB

i'm not a big fan of open baffles myself, doesn't sound right to me BUT from those i've heard, those were very good when using the b200 stock driver. imagine it will sound even better with some phase plugs as the high end was a bit erratic on the stock driver.
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Old 22nd November 2012, 02:08 PM   #5
mortron is offline mortron  Canada
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Nanook.... do you recommend the JE open baffles as a full range setup, or also in a FAST setup as well? I am toying with the idea of the slot loaded open baffles as my friend has two plate amps and 8 - MAX 8 woofers we are toying with trying out. I am not sure about the bass extension etc, and tradeoffs between using say the 1858 or a 15" or the slot load, and only time and reading will tell.
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Old 22nd November 2012, 08:08 PM   #6
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Quote:
Originally Posted by mortron View Post
So I have pestered and lurked for some time here, and yet to really start a project and share it with you all. This will be my first.
...Any helpful tips and or criticisms are welcome. I would like to thank the people I have been corresponding for their help on this, they know who they are

All in I have just under $100 into this, and I'm looking forward to living with these for some time.
I'm on the same learning curve, that for me started with a free pair of Fostex FE166e's. It's really worth doing some reading before you cut more wood or buy more drivers. My suggestions:

First, Rudolf Finke has published a paper called "Open Baffle Dipoles". I found a link to it here somewhere, and it is a terrific explanation of the basics of how a single driver works in an OB. (Thank you, Rudolf!). If you can't find it PM me and I'll mail you a copy.

2nd, download The Edge: Tolvan Data
and play with it. You'll learn a lot about what baffle sizes and shapes work and don't. RF's paper will help you make sense of what you're doing in The Edge.

3rd, go to Martin King's website Quarter Wavelength Loudspeaker Design and read his articles on OB design. A couple of times. It's well worth paying for his design worksheets - you'll need them. They are the basic tools that will help you integrate the B200 with whatever bass driver you wind up with.

Armed with all of that, you'll start getting an idea of what will work for you. From a quick look. I'd guess the B200 would work similarly to one of the Fostex drivers MK used in his projects (and I'm using in mine).

Have fun!

Bill
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Old 22nd November 2012, 08:21 PM   #7
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Joaquim Gerhardt had an open baffle project not too far back in time. It was for his personal use. You might try to find it. Of all the speaker manufacturers I know of, I would respect his efforts as much as any. You might try a search to find that info.
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Old 22nd November 2012, 11:08 PM   #8
Nanook is offline Nanook  Canada
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Default "JE Labs" or Slot bass?

Quote:
Originally Posted by mortron View Post
Nanook.... do you recommend the JE open baffles as a full range setup, or also in a FAST setup as well? I am toying with the idea of the slot loaded open baffles as my friend has two plate amps and 8 - MAX 8 woofers we are toying with trying out. I am not sure about the bass extension etc, and tradeoffs between using say the 1858 or a 15" or the slot load, and only time and reading will tell.
morton:
I recommend the "JE Labs" style for fullrange or coxial use , as long as the driver is 12" + and suitable for an OB design. But with the suggestion I made. Without it the bass will leave you wanting more. The simple addition of the extensions as described, provides you with significantly more bass. Everyone that I have recommended this to (even those who have built various versions of much narrower OBs, with much smaller drivers) has come back and commented that they then find the bass quality and depth of tone (but not quantity of the visceral stuff) to leave them satisfied. If you have the room, I would suggest these over every other OB, mainly because the simplicity of the build. If you don'y have the room, I would suggest some of the "wing type" OBs , but would still insist on a top plate and a means to secure the wings together.

If you are unfamiliar do a search for the Paul Barton "Project 1" loudspeakers of about 25 years ago (or older). These were about 6' tall, and 2' wide + 1' wings on either side. The wings were secured at a constant angle, with no gaps between the wings and the front baffle. I believe they also had built in woofers/subs that were active IIRC. In the case of this style of speaker (winged style OBs), the slot-loaded idea should work well. Nelson Pass providd some information regarding a slot-loaded sub/fullrange project, look here for it. If using 4 woofers/side then a FR driver could sit above them in either the much taller PSB P1 or the much shorter "JE Labs" style. (Because JE didn't design it, but popularized the dimensions, I always refer to this design in quotes. More correctly it should be called the "Stereo Sound Tube Kingdom" design).

I'm not familiar with the subs you mention, nor the amps so I cannot comment on those.

If I can I'll post a photo or drawing of the modified "Je Labs" OB. I've looked for information on the Paul Barton Project One loudspeakers to no avail.

gafhenderson: : The NoBox has been around for a while and Dick Oshler even made some mods to one I think.

for all: the enjoythemusic DIY articles have more than a few articles regarding OB types.
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Old 6th December 2012, 01:57 AM   #9
mortron is offline mortron  Canada
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Quote:
Originally Posted by Nanook View Post
morton:
I recommend the "JE Labs" style for fullrange or coxial use , as long as the driver is 12" + and suitable for an OB design. But with the suggestion I made. Without it the bass will leave you wanting more. The simple addition of the extensions as described, provides you with significantly more bass. Everyone that I have recommended this to (even those who have built various versions of much narrower OBs, with much smaller drivers) has come back and commented that they then find the bass quality and depth of tone (but not quantity of the visceral stuff) to leave them satisfied. If you have the room, I would suggest these over every other OB, mainly because the simplicity of the build. If you don'y have the room, I would suggest some of the "wing type" OBs , but would still insist on a top plate and a means to secure the wings together.

If you are unfamiliar do a search for the Paul Barton "Project 1" loudspeakers of about 25 years ago (or older). These were about 6' tall, and 2' wide + 1' wings on either side. The wings were secured at a constant angle, with no gaps between the wings and the front baffle. I believe they also had built in woofers/subs that were active IIRC. In the case of this style of speaker (winged style OBs), the slot-loaded idea should work well. Nelson Pass providd some information regarding a slot-loaded sub/fullrange project, look here for it. If using 4 woofers/side then a FR driver could sit above them in either the much taller PSB P1 or the much shorter "JE Labs" style. (Because JE didn't design it, but popularized the dimensions, I always refer to this design in quotes. More correctly it should be called the "Stereo Sound Tube Kingdom" design).

I'm not familiar with the subs you mention, nor the amps so I cannot comment on those.

If I can I'll post a photo or drawing of the modified "Je Labs" OB. I've looked for information on the Paul Barton Project One loudspeakers to no avail.

gafhenderson: : The NoBox has been around for a while and Dick Oshler even made some mods to one I think.

for all: the enjoythemusic DIY articles have more than a few articles regarding OB types.
Thanks Nanook,

Sorry it took me a while... school has been demanding as of late. I had originally planned on the JE labs open baffles, but wood on hand was almost ideal for the Darkstar Winged Open Baffle dimensions posted on the Wild Burro site. I have had more time to play with them and kick some ideas around.

I tried to install some 10X6" shelfs about 6 or so inches above to top of the driver, just made of multi layer cardboard. I am not sure what I think about it. I have trouble quantifying or qualifying the differences. Where on the baffle should the shelf sit?

I am currently using them with the inside wings removed. I feel like this added some imaging and filled up the centre a bit more than before. I am not sure what type of baffle I will employ when a bass driver is added. Some suggest the baffle obscures alot and with bass support is not as needed. I will have to see.

I am tempted to try the software to model, but am having difficulties understanding what it does and what to do
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Old 6th December 2012, 06:46 AM   #10
Nanook is offline Nanook  Canada
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Default Added 10 X 6 shelves...

Stereo Sound Tube Kingdom OB w:mods.pngWildBurro mod OB.png


Morton,

The shelves should be full width of the centre baffle. In my case, because I have uprights, I made the shelf full width between the uprights. I also added a verticle piece between the uprights. The red parts are the additions I made to the original OB type.

Remember that I am using a coaxial mount, not as pictured in the sketch, and that the driver is centred at 13-1/2" from the bottom of the baffle.

I'll try to sketch a Wild Burrows type OB and draw the structural mods that I think would work well for you. The use of cardboard is not suitable (even for testing) the structural portions of any OB.
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Last edited by Nanook; 6th December 2012 at 07:11 AM.
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