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Am I interpreting this right. It seems to have a sealed speaker box with a small open baffle mounted approximately 1 inch away from the speaker baffle with just dowel or something?
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I can see the possibility of having the baffle edge diffractions of the front and box baffles complement each other, at midrange frequencies. It will certainly make an audibly different sound, so it must be possible to optimize it.
That said, I have heard far too many "magical" boxes that work by optimizing multiple resonances and diffractions - rather than trying to eliminate then in the first place. The magic never lasts long for me. YMMV.
nt
Yea but I really need some new speakers. I have just put it off for so long as I don't enjoy sawdust and sweat but it is winter over here.
The possibility of effecting the sound in so many ways is beyond imaging. It could cancel a driver midrange peak even I thought. Large tapped threads instead of spacers make the gap adjustable and different baffles for front plate hole and secondary baffle make it fully adjustable and suitable to test many different drivers.
that's a very old idea and it is a 360 degree reflex vent right on the driver. Ought to work like a charm. Best regards Moray James.
moray james
An idea. This may be bad. Suppose the four sides of the baffle are curved out to make a vent like a horn all around. It can also be made straight instead of curved to get a tapered vent. Perhaps somebody has tried and given up. But with the new excellent drivers, it may be worth a try.
Cheers
Bill
you could make either of those ideas work but you would be made to tune by ear rather than using a design program. I expect that the real benefit this design may have is the fact that the vent acts so directly upon the cone action. Best regards Moray James.
moray james
still strange I cant see why it doesn't cancel
The mass of the air in the vent space delays the back pressure. It DOES cancel, below the tuning frequency. Same as any other ported design at low enough frequencies to use a lumped-element analysis.
It's a style of bass reflex, they've been around for at least 60 years. The advantage to it is if you mount the baffle to the cab with bolts, so that you can easily vary the distance to the box for tuning.
I'm listening to: A Trick of The Tale by Genesis
Thetubeguy1954 (Tom Scata)
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Are ok maybe isolating the driver on the small baffle might help too. Very strange .. At first glance it looks like something that just wouldn't work!
I have some boxes the right size that I can easily bolt a small baffle too. They say in the description that very low bass can be had from very small box sizes. But reflex is to inaccurate in the bass. Will this be any different?
This design pre-dates the use of T/S specs and modern ducted port formulas, and as I said its main advantage was the ease of seat of the pants tuning on the fly. Otherwise it works like any vented box, and it can be software modeled. But modeling gets very complicated if the baffle is square, while it's very easy if it's made round. It won't go any lower than any other vented box, because that's what it is.
As to "reflex is to inaccurate in the bass", that's simply not true. If it was so then bass reflex would not be the most commonly used alignment.
Ok I think I get it. Even though the front baffle is like a tiny open baffle. Bass wont cancel because the air is under pressure.
Thanks again. Making the dowel adjustable might make it a very tuneable box.
Unbelievably I might just actually do a pair of these.
A little differently. I will put my spin on it.
If you ignore the fact that the driver is mounted in the baffle it's easier to visualize how it works as a ducted port. A variation is this configuration, which places the baffle behind the cabinet front rather than in front of it. The two function identically.
that's looks close to a Jensen if you just turns the ports around and put them all the way along the sides. And like the Jensen I like that because the front baffle external resonances(honks) are shielded by the front panel and on the Jensen the inner side walls honks are masked up by the outer cabinet walls. Like carpet for pa horns.
I am surprised this design is not used more. I love the way the vent flows out around the driver. And the way the front baffle masked resonances as mentioned above.
And if it WEREN'T so, there wouldn't be a need for any other 'alignment'.
;-)
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