Hi
Could someone comment this project?
My main doubt is on bass alingnemt, if sealed or ported. The article didn´t mention.
http://www.arkada.com/kit/bt4.html
TIA
JC
Could someone comment this project?
My main doubt is on bass alingnemt, if sealed or ported. The article didn´t mention.
http://www.arkada.com/kit/bt4.html
TIA
JC
There is a port on the back of the back of teh box if you bothered looking at the diagram.. lol.. but thats not how I worked it out.. 🙂
I think the "port" on the back is actually the hole for the connector cup. Having typed that, I have seen a speaker where the port was just a circle cut into the MDF (Italian full-range with a beautiful blue cone and gold whizzer - Redekcho?).
Nice one,
David.
Nice one,
David.
I don't know, Skinny Boy, it looks like a tough call to me. Asssuming the building material was 18 mm thick-roughly equivalent to 3/4 inch-then the interior has a volume of 17.8 liters, or .63 cu ft. This is averaging the depth of the top and the bottom, which are different because of the slant of the front baffle.
I modeled the Peerless 850122 woofer in both vented and sealed cabinets. The ideal vented cabinet for this should be about twice as large, but this size is perfectly serviceable if vented at 40 Hz, which this model is.
The sealed model comes out to a Qtc of .7, which many speaker designers say is the ideal Qtc for a sealed box.
The F3 of the ported box is 45 Hz, which corresponds to the manufacturer's stated range of 45 Hz. However, at 45 Hz the sealed box is 6 dB down, and I have seen sealed box manufacturers give the 6 dB down point as the lowest frequency in it's range. Fudging, but not too bad. Besides, sealed box advocates can say that since the rolloff is more gradual, you eventualy get more bass than the ported design.
I don't see any ports in the diagram. While some boxes only require a hole in the baffle, to tune this woofer in this size box to 40 Hz requires a vent that is 2" diameter by 6.75 inches long. Larger diameter vents require even longer vents. As for the hole in the back, it probably is what daatkins says it is. With a "perfect" Qtc of .7, it would be highly unlikely to be an aperiodic vent, like a variovent.
So this thing is either a sealed design that many designers would label "perfect" or an imperfect but very decent ported design.
But I don't see any 6 inch or longer vents.
My guess is-it's a sealed design.
This is a project where you might have some fun and put in a 2 " diameter pipe that extends out the back that can have a cap screwed on. Hardware stores have such PVC pipe. Screw the cap on-it's a sealed design. Screw it off-you have a ported.
See what you like best. But overall, I would bet it is a sealed design.🙂
I modeled the Peerless 850122 woofer in both vented and sealed cabinets. The ideal vented cabinet for this should be about twice as large, but this size is perfectly serviceable if vented at 40 Hz, which this model is.
The sealed model comes out to a Qtc of .7, which many speaker designers say is the ideal Qtc for a sealed box.
The F3 of the ported box is 45 Hz, which corresponds to the manufacturer's stated range of 45 Hz. However, at 45 Hz the sealed box is 6 dB down, and I have seen sealed box manufacturers give the 6 dB down point as the lowest frequency in it's range. Fudging, but not too bad. Besides, sealed box advocates can say that since the rolloff is more gradual, you eventualy get more bass than the ported design.
I don't see any ports in the diagram. While some boxes only require a hole in the baffle, to tune this woofer in this size box to 40 Hz requires a vent that is 2" diameter by 6.75 inches long. Larger diameter vents require even longer vents. As for the hole in the back, it probably is what daatkins says it is. With a "perfect" Qtc of .7, it would be highly unlikely to be an aperiodic vent, like a variovent.
So this thing is either a sealed design that many designers would label "perfect" or an imperfect but very decent ported design.
But I don't see any 6 inch or longer vents.
My guess is-it's a sealed design.
This is a project where you might have some fun and put in a 2 " diameter pipe that extends out the back that can have a cap screwed on. Hardware stores have such PVC pipe. Screw the cap on-it's a sealed design. Screw it off-you have a ported.
See what you like best. But overall, I would bet it is a sealed design.🙂
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Yeah, but to get the frequency response they claim, you would need a vented box, you wouldn't get anywhere near the bass they say in a sealed box... but... Yeah, your probably right. . 🙂 lol 😛
Skinny Boy:
Even high end speaker systems costing in the thousands of dollars have specs that frequently exaggerate the bass extension. I used to read Audio magazine, and in their speaker reviews, the manufacturer's spec for F3 would actually be 6 dB or 9 dB down when the reviewer tested the systems and displayed the chart.
This speaker would be 6 dB down at 45 Hz in a sealed box of 17.9 liters. Calling the F3 45 Hz is far from the worst fudging I have ever seen. 🙂 🙂
Even high end speaker systems costing in the thousands of dollars have specs that frequently exaggerate the bass extension. I used to read Audio magazine, and in their speaker reviews, the manufacturer's spec for F3 would actually be 6 dB or 9 dB down when the reviewer tested the systems and displayed the chart.
This speaker would be 6 dB down at 45 Hz in a sealed box of 17.9 liters. Calling the F3 45 Hz is far from the worst fudging I have ever seen. 🙂 🙂
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