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Multi-Way Conventional loudspeakers with crossovers

Redesigning my cabinets. Thoughts?
Redesigning my cabinets. Thoughts?
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Old Yesterday, 08:47 PM   #71
3wayaddict is offline 3wayaddict  Netherlands
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I also was already thinking. The angle at which it is slanted only make a small difference in height. The top of the "wedge" is only 20 cm higher than the bottom, which is quite small in comparison to wavelengths of 1> m.
So it won't have much if any effect?
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Old Yesterday, 09:03 PM   #72
3wayaddict is offline 3wayaddict  Netherlands
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Let's say I'll fill it with thick stuff to as high as the bottom woofer. This will damp very heavily. What difference will this large amount of dampening make to the sound? Qtc will lower and standing waves will be reduced but what will it do to the resulting sound? When I had a too big stash of left-over dampening material in my room the bass wasn't really perceivable and really not their. In case of the midrange chamber it really compressed dynamics but mainly made the sound overly bright, lose its weight and ruin the soundstage and imaging.
Will there be any of these negative effects in the bass enclosure if there is a lot of heavy damping? Or is this not the case with bass enclosures?
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Old Yesterday, 09:15 PM   #73
planet10 is offline planet10  Canada
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Redesigning my cabinets. Thoughts?
Quote:
Let's say I'll fill it with thick stuff to as high as the bottom woofer.
The entire enclosure will need to be filled.

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Old Yesterday, 09:37 PM   #74
3wayaddict is offline 3wayaddict  Netherlands
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All walls will be covered with normal poly fill, the stuff you find in pillows. But I'm talking about the very dense stuff.
But how about the specifications of the enclosure then?
In unibox with damping on "walls covered" the qtc is at 0,707 in a volume of 72 L with a F3 of 44,9 Hz. But this changes with the damping. With the damping at "heavy fill" qtc is at 0,707 in a volume of just 49 L with a F3 of 49,4 Hz. keeping the volume at 72 L gives a qtc of 0,632 with a F3 of 47,5 Hz but more graduate roll off and the woofers reach Xmax quicker.
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Old Yesterday, 10:00 PM   #75
danny_66 is online now danny_66  Belgium
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For your mid cabinet I would make the bottom and top more narrow, so there's more diffusion.
A bit like XTZ did in their Divine.
As stuffing for the mid: Twaron angelhair 3gr/liter, works phenomenal !
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Old Yesterday, 11:33 PM   #76
planet10 is offline planet10  Canada
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Redesigning my cabinets. Thoughts?
Quote:
Originally Posted by 3wayaddict View Post
...with damping on "walls covered" the qtc is at 0,707 in a volume of 72 L with a F3 of 44,9 Hz...at "heavy fill" qtc is at 0,707 in a volume of just 49 L with a F3 of 49,4 Hz. keeping the volume at 72 L gives a qtc of 0,632 with a F3 of 47,5 Hz...
Polyfill will not be very effective on the walls. It should fill the enclosure. As well as the volume you fill there is the density you fill it at. Well teased polyfill can compress to pretty dense. We would also line the walls near the drivers with 12mm cotton or wool felt. I second the suggestion of quality “polyfill”. Acoutastuff is readily available over here so is what we use.

Note that to humans F3 is meaningless (Toole). What is F6/F10?

I like to target Q = 0.58 with sealed boxes i do. It better accounts for typical room gain.

dave
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Old Today, 11:22 AM   #77
3wayaddict is offline 3wayaddict  Netherlands
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Okay, well I was just thinking of fiberglass wool you'd normally put in the walls to keep your house warm since it's very effective and cheap. It does spread quite some nasty particles though but this shouldn't be a problem because it's a sealed enclosure. Will this be effective or does it have to be combined with other kind of material as well? The sheep wool is quite expensive.
There seem to be a lot of different kinds of material and everybody says different things about their qualities.
What are the different options for damping material and which are most effective and for what use?
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Old Today, 11:41 AM   #78
3wayaddict is offline 3wayaddict  Netherlands
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So I removed the slanted top and bottom and did some other tweaks to the enclosure again to make the design and eventual construction a lot simpler and make the enclosure stronger in the end.
I made the baffles slightly wider to 24,5 cm so the entire woofer, including the mounting lips fit in the width of the baffle. This way the recessed edge around the mounting hole were the mounting lips of the woofer fall into can be done directly by CNC instead of having to do it by hand with a mill after everything has been put together. This makes it a lot simpler, I no more need advanced tools and perhaps the help of a woodworker which saves a lot of time and fuss.
Making the baffle slightly wider made the entire enclosure to become slightly wider. The width of the back of the enclosure on which the amplifiers will be mounted will would always be 13 cm. Because the difference in width between the widest point of the enclosure, in the middle, and the width of the back plate is now bigger, the diameter of the rounding has increased slightly, again slightly improving internal acoustics. The extra width also made for some more volume but because a bigger volume isn't necessary and there are limits to how big the volume should get (though it's nowhere near to getting too big yet) this left some space for some more wood. So, I increased the thickness of the side walls to 3,5 cm/1-1/3", again making the cabinet stronger, stiffer and heavier.

Also, this is kind of a coincidence with the dimensions, but one of the big braces now doubles as the top plate for the amplifier chamber. This again makes it simpler, saves two pieces of wood, and eventually makes the amplifier chamber in and the construction around it stronger and reduces the risk of leaks.

There now are horizontal braces every four layers/10 cm. And there is a vertical brace amongst the entire height of the cabinet with the edges around the holes in them against the horizontal braces, again reinforcing them. This skeleton in combination with the 5 cm thick baffle and 3,5 cm thick side walls will make for a extremely stiff cabinet.
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Old Today, 12:15 PM   #79
AllenB is offline AllenB  Australia
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Just as you found with your diffusers, sound has a size and that's important when damping.

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Originally Posted by 3wayaddict View Post
fiberglass
Is much more effective than polyfill.
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Old Today, 12:21 PM   #80
3wayaddict is offline 3wayaddict  Netherlands
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I know it's much more effective. But I though having extra dense material was only necessary for the big stash in the bottom.
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