Hi,
1st prototype of my sealed alpair 12p LCR box is almost ready.
Its internally a golden ratio rectangle 13x21x34 cm made slightly trapezoid to avoid parallel surfaces.
Volume is 9.3 liters without the alpair, which should get me close to the ideal 8.3 liters, and leave some room for tweaking with stuffing.
Now I Need to cut he hole for the alpair... from a design standpoint, i want it dead center.
The bottom of box is 36mm thick and top is 18mm, so internally it is offset.
The box has been acclimatizing for a week now, so it shouldn't contract/expand much more causing my hole cut to become an oval.
- I don't believe baffle step will be that big of a problem, since i have rounded two edges (r16mm was the larges available for my 8mm router), and the speaker will be wall mounted on bracket and angled toward LP.
But if offsetting helps, how small of a vertical offset can i get away with?
External dimension is 390x290x180 mm
The system will be tweaked and calibrated with audyssey xt32 + app.
And yes, I know the alpair 12p might be better suited in another cabinet type, but I'm giving it a go anyway 🙂
1st prototype of my sealed alpair 12p LCR box is almost ready.
Its internally a golden ratio rectangle 13x21x34 cm made slightly trapezoid to avoid parallel surfaces.
Volume is 9.3 liters without the alpair, which should get me close to the ideal 8.3 liters, and leave some room for tweaking with stuffing.
Now I Need to cut he hole for the alpair... from a design standpoint, i want it dead center.
The bottom of box is 36mm thick and top is 18mm, so internally it is offset.
The box has been acclimatizing for a week now, so it shouldn't contract/expand much more causing my hole cut to become an oval.
- I don't believe baffle step will be that big of a problem, since i have rounded two edges (r16mm was the larges available for my 8mm router), and the speaker will be wall mounted on bracket and angled toward LP.
But if offsetting helps, how small of a vertical offset can i get away with?
External dimension is 390x290x180 mm
The system will be tweaked and calibrated with audyssey xt32 + app.
And yes, I know the alpair 12p might be better suited in another cabinet type, but I'm giving it a go anyway 🙂
Attachments
If you want it dead centre, put it dead-centre and enjoy, since that is where your priority lies. Life is too short to get overly worried. If you wish however, try centre 141mm down from the internal top.
“Slight” will actual make little to no difference.
If you put the required chamfer on the back of the driver cutout, it turns out that the volume added by that chamfer is very close to the volume the driver takes up inside the box. So your net volume will likely still be very close to 9.3 litres. Add stuffing and it will be more like 10-11 litres equivalent.
Crossover to woofers just above 100 Hz?
BTW, where did you getteh “ideal” 8.3 litre? Butterworth is about 7 litre or a bit less stuffed, up to about 11-12 litres will still give good Q and bit better phase.
The roundover will have zero affect of the baffle step.
The box looks pretty but the use of translam seems such a waste. You end up using way more material for a less sturdy enclosure.
dave
I Think it was actually from one of your simulations showing 8.3 liters at Q(tc) 0.707
But I might have interpreted that wrongly.
I was thinking of adding sand to chamber to adjust internal volume, and to keep humidity fluctuations down, but it seems now I might need a bigger bag of sand :-D
I will post an image of the ugly innards shortly.
Yes crossover somewhere in the area of 100-120 Hz
But I might have interpreted that wrongly.
I was thinking of adding sand to chamber to adjust internal volume, and to keep humidity fluctuations down, but it seems now I might need a bigger bag of sand :-D
I will post an image of the ugly innards shortly.
Yes crossover somewhere in the area of 100-120 Hz
This is what i would have posted.
You are right. 8.3 litre. With stuffung 7.5 litres or so.
dave
