Arround 2010 I completed an amp based on LM3886 and was looking for a good speaker. Many friends here in this forum helped me making the amp and finally a great suggestion came from Picowallspeaker directed me to Martin King open baffle. At first the size frightened me. But nevertheless I jumped into it for its simplicity and built one. The details are in the thread Suitable Speakers.
Since then my work and home forced me to look away from electronics. Enjoyed the open baffle for several years and then for a couple of year the music also took a back seat. Termite sneaked in and started eating the baffle without my knowledge. About a month back I tried to put back the system and noticed time has taken its toll on the machines also. Lots of work now.
In the mean time around 2017 Martin King revised his design depending on the full range model used.
At the moment I am now working on this project. Got back my Marantz CD5003 back on its feet. The turn table is alright, the amp is as new as before. The radio FM needs attention as it has gone silent.
The revised crossover suitable for Fostex 103En is done. Only the baffle needs a complete new making. Still looking for material for it to make it better than before. Any experienced suggestion is welcome.
I have a question now. In an open baffle speaker the drivers can be attached to the baffle in two ways. One is place the driver over the hole and another is passing the magnet through the hole and then fix it. In either case I will be curving out the rim of the hole for free flow of the sound waves. My question is which is better/correct sonically. Aesthetically the first option looks better because the screws aren't visible. Thanks for response in advance.
Will post my journey details here.
Thanks and regards
Roushon.
Since then my work and home forced me to look away from electronics. Enjoyed the open baffle for several years and then for a couple of year the music also took a back seat. Termite sneaked in and started eating the baffle without my knowledge. About a month back I tried to put back the system and noticed time has taken its toll on the machines also. Lots of work now.
In the mean time around 2017 Martin King revised his design depending on the full range model used.
At the moment I am now working on this project. Got back my Marantz CD5003 back on its feet. The turn table is alright, the amp is as new as before. The radio FM needs attention as it has gone silent.
The revised crossover suitable for Fostex 103En is done. Only the baffle needs a complete new making. Still looking for material for it to make it better than before. Any experienced suggestion is welcome.
I have a question now. In an open baffle speaker the drivers can be attached to the baffle in two ways. One is place the driver over the hole and another is passing the magnet through the hole and then fix it. In either case I will be curving out the rim of the hole for free flow of the sound waves. My question is which is better/correct sonically. Aesthetically the first option looks better because the screws aren't visible. Thanks for response in advance.
Will post my journey details here.
Thanks and regards
Roushon.
IME mounting the woofer on the back side of the baffle is just fine. There isn't any audible cavity resonance in the hole cut into a 18-25mm thick baffle that the woofer would excite. Rounding over the edge of the hole will kill diffraction issues, it there are any, tho not to likely at woofer frequencies.
With the Fostex it's a different matter. The front wave is more important than the rear wave, so the small driver should be front mounted with plenty of relief at the back, as you plan to do. The 4" driver can even be mounted on a thin sub-baffle in a larger hole. Over in my Manzanita thread you'll see some examples of what other people have done sinking a small driver into an open baffle.
With the Fostex it's a different matter. The front wave is more important than the rear wave, so the small driver should be front mounted with plenty of relief at the back, as you plan to do. The 4" driver can even be mounted on a thin sub-baffle in a larger hole. Over in my Manzanita thread you'll see some examples of what other people have done sinking a small driver into an open baffle.
I'm currently working with small drivers on an OB. I'd love to have a tool that would cut a perfect exponential shape ring in the wood so I could rear mount. Otherwise it's up to pure woodworking skill to shape such, which I do not have.
One of the things I've also played with is damping the baffle board - otherwise it's just like knocking on a door, which is far from ideal. I've also experimented with elastic suspension of the driver to the baffle board, to reduce conducted vibrations from exciting the baffle board.
One of the things I've also played with is damping the baffle board - otherwise it's just like knocking on a door, which is far from ideal. I've also experimented with elastic suspension of the driver to the baffle board, to reduce conducted vibrations from exciting the baffle board.
Thanks a lot Pano for the explanation. In my case there will be two boards glued together to make one baffle. So for the full range, I can make a bigger hole in one and on the other one a hole of the size of the full range, before gluing. I just had a look at Manzanita open baffle and it is clear now.
Regards
Roushon.
I am sure you know, there are some palm router bits which can do the job. I attach a picture.
Attachments
Would it pays off to make a roof plan on the OB sub to have a base for the upper fullrange OB in order to time align phisically the two drivers around the cross operatin filter point if made passive ?
If you are using shallow slopes, some spread between the crossover points and not crossing very high, IME the alignment won't get you much. For box speakers with crossovers in the 2 kHz range, sure, alignment is going to make a difference.
Given the low XO point they are likely close to time aligned physically, but as soon as the XO gets added in (2nd order?) it goes out the window?
dave
OK -
I tried to dampen the panels with cork, sandwiched between scrap MDF and the baffle board. Still rings when tapped - but better than it was. The driver is mounted on a ring of ~1/4" black rubber mat, which is actually pretty stiff; no sagging, yet you can wiggle the driver a bit when grabbed by the magnet. So again - some isolation - better than solid connection to the board.
I havent gone really off the deep end with sand-filled panels; my efforts more along the lines of one should at least try to reduce panel ring in an OB.
I tried to dampen the panels with cork, sandwiched between scrap MDF and the baffle board. Still rings when tapped - but better than it was. The driver is mounted on a ring of ~1/4" black rubber mat, which is actually pretty stiff; no sagging, yet you can wiggle the driver a bit when grabbed by the magnet. So again - some isolation - better than solid connection to the board.
I havent gone really off the deep end with sand-filled panels; my efforts more along the lines of one should at least try to reduce panel ring in an OB.
My previous speakers (pictures) are in the thread Suitable Speakers. I couldn't add the link here. It was 35mm thick, two plywoods glued together. Pretty heavy. Sounded fabulous.
Martin has a newer design out. It's a lot more compact and uses slightly different crossover points.
I believe this one is only 20 " wide and 24 " tall. I wonder if it would still work if I used a 6 db/oct
xover instead of a 12 db/oct xover ? http://www.quarter-wave.com/Project12/Project12.html
I believe this one is only 20 " wide and 24 " tall. I wonder if it would still work if I used a 6 db/oct
xover instead of a 12 db/oct xover ? http://www.quarter-wave.com/Project12/Project12.html
That rubber mounting is interesting. I've built a very basic OB that's promising but I need to work on a much better baffle.
Or even simplier, mount your speaker on a first baffle plan put another one in front of with few mm spacing.,just a round rubber around the first speaker baffle around the hole will assure proofing with the floating front baffle in order it does not shake.. you certainly do not care much than the first plan with speaker on it shakes back waves. But you want the first baffle not being a driver plan that emits in front of you. This one floating has no vibration. Eventually put the little mid unit on the first bafle. Want save wood, swap the first bafle by let it floating on ropes but increase the decoupling proofing with the first floating baffle to avoid vibrations transmission but still permit the acoustic short. I think a very lossy latex ring could do it...
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