I don't mind using good plywood, the reason that I had the idea to use mdf was that someone told me mdf is denser and heavier which is more suitable for this application. Is that not true?
Cool! Thanks!
At Qts' = 2, no baffle is required, it is the baffle.
Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
GM
That is true. MDF is both dense & heavy, 2 things that are not assets when they do not bring extra rigity. In mdf it does not so those are drawbacks.
Now about as dense & heavy, but a zillion times stiffer (and way prettier) is stranded/fossilized bamboo plywood.
Good plywood is the goto bang for the buck, but some of the exotic mdfs like medite are better than the basic home despot kind.
Even then, with an OB some “i-beam” structure would not hurt. Or isolate/mount the drivers on a rigid, heavy spine and flot the baffle in front of it (gasket on the front of the driver(s).
dave
thank you very much. that is very helpful. i have the drivers on the way and i think that i will check out some plywood. i have seen people use those butches block counter tops as the baffle, while it looks pretty it is more expensive that i want to do but I do plan on veneering it if it actually turns out to be a keeper.
For those with drivers on the way and wondering what to do, maybe check out The Edge program at Tolvan Data
There's a checkbox for "open baffle" and if you know your board is 2' wide, you can choose a height and then place to driver anywhere on the board surface. It outputs a frequency response; I was told the useful part is the hump and dip near where the low frequencies start to roll off. Driver placement position on the baffle effects the hump and dip magnitude; there's better positions than others regarding minimizing these.
When I tried to model my baffles, I chose a position (one of several) that I felt minimized the OB hump/dip characteristic. That position however was not optimal for bass response, so I have to compensate by trying an arrangement of wing structures on the rear of the board.
They certainly seem to improve the bass extension, assuming by blocking the rear wave from wrapping around the baffle so easily to cancel the front... I'm trying to make the structure not be excessive to avoid introducing unwanted artifacts, such as a tubby sound, by making it "1/2 a tub" at most - only compensating for the "short side" of the offset. I've got another piece to glue in place on each board to extend the block a bit down the short side -
There's a checkbox for "open baffle" and if you know your board is 2' wide, you can choose a height and then place to driver anywhere on the board surface. It outputs a frequency response; I was told the useful part is the hump and dip near where the low frequencies start to roll off. Driver placement position on the baffle effects the hump and dip magnitude; there's better positions than others regarding minimizing these.
When I tried to model my baffles, I chose a position (one of several) that I felt minimized the OB hump/dip characteristic. That position however was not optimal for bass response, so I have to compensate by trying an arrangement of wing structures on the rear of the board.
They certainly seem to improve the bass extension, assuming by blocking the rear wave from wrapping around the baffle so easily to cancel the front... I'm trying to make the structure not be excessive to avoid introducing unwanted artifacts, such as a tubby sound, by making it "1/2 a tub" at most - only compensating for the "short side" of the offset. I've got another piece to glue in place on each board to extend the block a bit down the short side -
Is this the bamboo ply you're talking about?
Solid Panel High Density(R) Caramel 20mm : BP-DT1050 – Moso Bamboo Surfaces
I can’t say. it is similar construction (uses longer blocks on the inside), the question is how are the outer layers made.
In stranded they are the long fibres imbedded in somesort of matrix to hold it togethr. In peron you can see, as the surface is way harder than the cheaper variations which have surface layers with bamboo sliced horizontally or vertically.
PlybooStrand Bamboo Plywood and Veneer | Plyboo
But as a wild guess, this stuff is likely the lesser stuff given its price. I’d expect it to be more expensive in the UK.
dave
The position on the baffle will affect the ripples above the dipole peak, these can be smoothed by having as much variation in distance between driver and baffle edge as possible.
@tooppy - If you look back at post #35, there's a few pictures showing the Edge program UI and a corresponding frequency response plot. The first simulation I did had the driver centered and produced a 5 db hump, the next simulation I moved the driver closer to the edge and now it's 3db. So there's an example of this program providing a frequency response plot corresponding to driver position on the panel.
It's just one way of helping to decide where to place the driver. I just played on it until I got the hang of what approaching an edge with the speaker did to the frequency response / hump. Certain I was going to use an asymmetric offset, I then hunted around the baffle model with the driver for a frequency response I liked; a 2 db step I believe. With my intuition's approval and coordinates in hand, I proceeded with the project. I still got one more board or two to place and a couple other details, but soon I'll do actual frequency response measurements to see how they behave in the room. The tree is gone.
So far, with a little player EQ they're doing everything right - except that low bass.
That's improving with the winging of the backside of the baffle. I'm really glad I got these and first tried them in an OB. As I gain time with them, there's been many instances of "Well - I - never heard that song quite like that before!" To me, their frequency response sounds just right and the sonic image they make on some material is addictive. Just a lot of fun to listen to, no fatigue at all and can go in an evening from the 2020 Vienna Philharmonic New Year's Concert to the Chinese animated action film "Ne Zha" and do great with both.
It's just one way of helping to decide where to place the driver. I just played on it until I got the hang of what approaching an edge with the speaker did to the frequency response / hump. Certain I was going to use an asymmetric offset, I then hunted around the baffle model with the driver for a frequency response I liked; a 2 db step I believe. With my intuition's approval and coordinates in hand, I proceeded with the project. I still got one more board or two to place and a couple other details, but soon I'll do actual frequency response measurements to see how they behave in the room. The tree is gone.
So far, with a little player EQ they're doing everything right - except that low bass.
That's improving with the winging of the backside of the baffle. I'm really glad I got these and first tried them in an OB. As I gain time with them, there's been many instances of "Well - I - never heard that song quite like that before!" To me, their frequency response sounds just right and the sonic image they make on some material is addictive. Just a lot of fun to listen to, no fatigue at all and can go in an evening from the 2020 Vienna Philharmonic New Year's Concert to the Chinese animated action film "Ne Zha" and do great with both.
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Hi jjasniew, thanks for your reply, I was talking of pictures of your OB, back, front & sideways if you can. This give an added idea to everyone.
If anyone in UK wants to buy a pair of F15, I have a pair barely run in I will sell.
I first bought fast 10, also available to buy, then bought crystal 10 and F15 together. Crystal 10 are slightly better than fast 10 but not twice as good as is the price. F15 sound great in open baffle and something I could live with if I had the room. They were tested on 4' x 2' baffle. I'm asking £200 plus postage in uk only.
I first bought fast 10, also available to buy, then bought crystal 10 and F15 together. Crystal 10 are slightly better than fast 10 but not twice as good as is the price. F15 sound great in open baffle and something I could live with if I had the room. They were tested on 4' x 2' baffle. I'm asking £200 plus postage in uk only.
I've read thru this thread, sorry I didn't see it earlier. Interesting project and driver. 
How is your tonal balance? Getting a correcg tonal balance from a single driver on OB is going to be tricky. As you've learned, below a certain point bass losses are going to be significant on an open baffle. Your bass response then limits your top end level if you want flat response. That's easier to deal with using a 2 or 3 way speaker than a single driver. How's it going?
How is your tonal balance? Getting a correcg tonal balance from a single driver on OB is going to be tricky. As you've learned, below a certain point bass losses are going to be significant on an open baffle. Your bass response then limits your top end level if you want flat response. That's easier to deal with using a 2 or 3 way speaker than a single driver. How's it going?