Thanks Heraldo! I hope it's worth all the trouble 🙂 Yesterday I ordered the MiniDSP OpenDRC-DA8 .This should be the perfect tool to get a good sound.
Charles, the felt is 15mm thick. Maybe it's better to use 30mm eggcrate foam? What about stuffing, or lining on top of the felt/eggcrate foam, the box with sheep wool to lower Fb?
Wae, No I used lamellos. I did use some screws in the 25mm strips that hold the baffle. Unfortunately I placed screws where the screws of the baffle go through. They're blocked. Stupid mistake which I have to fix with some chiseling and 2C woodfiller 🙁
Charles, the felt is 15mm thick. Maybe it's better to use 30mm eggcrate foam? What about stuffing, or lining on top of the felt/eggcrate foam, the box with sheep wool to lower Fb?
Wae, No I used lamellos. I did use some screws in the 25mm strips that hold the baffle. Unfortunately I placed screws where the screws of the baffle go through. They're blocked. Stupid mistake which I have to fix with some chiseling and 2C woodfiller 🙁
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Do not overstuff a ported box.
They kinda need space to breath and obviously a direct path from woofer cone to port unobstructed by stuffing/damping.
You do not want to lower Fb since woofer, box volume and port are parts of a tuned system. Can't change one without affecting the others.
The idea of damping in a ported box is to absorb as much midrange as possible to stop it from exiting the box either via the port or through the woofer cones.
You do not want it to affect anything below about 150-200Hz because that is were the port starts to get involved.
I'd line the box with the felt but not the baffle and try some of that 30mm eggcrate foam on the back wall behind the woofers.
You can just stick in there loose and listen before making up your mind which sounds best.
They kinda need space to breath and obviously a direct path from woofer cone to port unobstructed by stuffing/damping.
You do not want to lower Fb since woofer, box volume and port are parts of a tuned system. Can't change one without affecting the others.
The idea of damping in a ported box is to absorb as much midrange as possible to stop it from exiting the box either via the port or through the woofer cones.
You do not want it to affect anything below about 150-200Hz because that is were the port starts to get involved.
I'd line the box with the felt but not the baffle and try some of that 30mm eggcrate foam on the back wall behind the woofers.
You can just stick in there loose and listen before making up your mind which sounds best.
Thanks Charles, some tinkering will be done with the damping. Today I repaired two inserts that were to close to the edge. The wood broke. Glued in two oak pieces and routed them after installing the inserts. The clue is to support the wood with a clamp before installing the insert. The brace is not perfectly in the middle. Next time I make the back support brace for the baffle out of one sheet mdf. I test fitted the baffle with the Volt and it fits perfectly. The back of the volt will rest against a felt strip.
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Just to clarify a couple of points.
Firstly, the resonance provided by the ports is incompressible and so a clear path between woofers and ports is unimportant. The incompressible slug of air oscillating in the ports is driven by the woofers raising and lowering the pressure in the cabinet. When the air is entering the cabinet what is around is relatively unimportant because the air will enter as a jet but when it is sucking it will draw air from all directions around the port mouth and this should be as clear as practical. Rounding the mouth will also help significantly. Placing foam near the mouth will use some of the available pressure drop to suck air through the foam leaving less to drive the resonance.
Secondly, you have a large cabinet with (I think?) the woofers significantly driving the lowest internal cabinet modes. This will need damping and placing damping materials on the walls where the velocity is zero will do little to help. You need it in the middle where the velocity is a maximum.
Firstly, the resonance provided by the ports is incompressible and so a clear path between woofers and ports is unimportant. The incompressible slug of air oscillating in the ports is driven by the woofers raising and lowering the pressure in the cabinet. When the air is entering the cabinet what is around is relatively unimportant because the air will enter as a jet but when it is sucking it will draw air from all directions around the port mouth and this should be as clear as practical. Rounding the mouth will also help significantly. Placing foam near the mouth will use some of the available pressure drop to suck air through the foam leaving less to drive the resonance.
Secondly, you have a large cabinet with (I think?) the woofers significantly driving the lowest internal cabinet modes. This will need damping and placing damping materials on the walls where the velocity is zero will do little to help. You need it in the middle where the velocity is a maximum.
I understand Andy, so lightly stuffing the cabinet with some sheepswool will benefit the damping of the 1/4 wavelength standing waves? (horizontal 134hz, vertical 230hz).
The boxes are rather big. Drying the filler in the sun:
The boxes are rather big. Drying the filler in the sun:
Reading this: chamfering driver holes I was wondering if it would be better to route a large 45 degree chamfer between the woofer mounting holes at the back of the baffle
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Felt is too dense as a stufing, and it will also be a narrow band absorber, likely in the highs only, so prob not that good as a midrange absorber.
You may need more than light stuffing because damping material is not particularly effective at low frequencies. "Transmission line" speakers rely on this in order to work.
Ok I will do some serious stuffing. In the meantime I installed the port support braces and repaired the blocked screw. The cabs are grinded and ready for the 1/4 round milling.
The OpenDRC-DA8 is delivered. Nice looking case. Also ordered an EMM-6 for the measurements.
The paint I have chosen is Sigma S2U Nova matt RAL 9005
The OpenDRC-DA8 is delivered. Nice looking case. Also ordered an EMM-6 for the measurements.
The paint I have chosen is Sigma S2U Nova matt RAL 9005
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Sanded and finished the baffles. Bassreflex pipes are sawn. 1/4 roundover on the cabinets is done. Did some final filling. Almost time to paint.
Thanks Jamwat, I want to do the base coat with a roller myself and then spraypaint the cabs at a friend who is building a car and has a spray booth.
Ral 9005 mat finish. Hopefully they will look sick when Im done 🙂 first layer of base coat is applied. There are still some patches that need to be filled but it looks promising. The baffle will receive a couple of hardwax oil layers.
Wish these were mine... think I’d go cherry red with silver flakes...
Shame you’re not local cause I’d love to hear these.
Shame you’re not local cause I’d love to hear these.
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