Can you elaborate on the eggcrate foam statement ?
Insulation and polyfill in a box speaker emulates a larger cabinet volume. OB already has a large "cabinet volume". Does the eggcrate foam dampen the cabinet/wing's resonance, reduce the rear chase volume (add more resistance/drag) and/or something else ?
What is the delta in sound and measurements ?
Thanks much.
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Lining a speaker box with eggcrate, wool felt, or melamine foam sponges helps to reduce back reflected sound out through the cone front. The back reflection can cause some interference (dips and peaks) at the higher frequencies corresponding to the distance to the reflecting surface. Woofers will have some output that is out of band and reducing the back reflection will give a clearer midrange. I don’t have measurements yet.
Would adding a slight angle (bell) to the back side wings to eliminate the parallel reflective surfaces provide similar functionality ? The reflections would be banked out the back of the OB chase instead of directly back at the bass cones.
Yes that helps but you would still have extra out of band woofer “noise” coming out the back and into the walls. It actually sounds quite good without it but I think it can’t hurt to have it. I’m looking forward to having time to measure and compare to see if the distortion (from back reflecition) figures go down.
Hi XRK as usual many thanks for your ever on going speaker experiments. This Slob thingy got me thinking if there's some nice 12 inch woofers working in a pair that can go down to 40hz with high sensitivity. Would be great to match it with a horn mids & something like GR Neo 3 tweeters
Many thanks & Kudos
Many thanks & Kudos
Maybe go with four 12in woofers and the 13in deep chamber depth gives you 1/4-wave upper extension of 250Hz. That would be a massive amount of cone area for high sensitivity bass. You can wire it series parallel for +6dB and nominal 8ohms. The midrange would need to go down lower to cross at 250Hz. Not sure if a reasonable size horn can go that low. It would sound amazing though.
Two drivers might be enough Sd at 518 cm^2. Delta 16ohm max is 98 dB and parallel is 8 ohm and 104dB, add 2.5dB slob gain and subtract 6dB ob loss. About 100dB overall.
Two drivers might be enough Sd at 518 cm^2. Delta 16ohm max is 98 dB and parallel is 8 ohm and 104dB, add 2.5dB slob gain and subtract 6dB ob loss. About 100dB overall.
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How about getting higher extension from a pair of 12" woofers by mounting them on a small slot with magnets out?
Maybe a pair of GRS 12" on a say 8"x 8" x 4"" front slot with both magnets out.
Usually a 12" might get a 13" deep slot but why bother giving it so much depth when the slot opening is restricted to say 13" x 3" ~ 40sq"
A 8" x 8" square woofer opening x2 is going to unload the woofers output, compared to the slot mouth area.
Maybe a pair of GRS 12" on a say 8"x 8" x 4"" front slot with both magnets out.
Usually a 12" might get a 13" deep slot but why bother giving it so much depth when the slot opening is restricted to say 13" x 3" ~ 40sq"
A 8" x 8" square woofer opening x2 is going to unload the woofers output, compared to the slot mouth area.
Would an arrangement similar to this with half clam shells shorten the average chamber depth or provide any advantages for larger drivers like bringing their centers further in line with the front baffle ?
ecobox3
I am not sure where the chamber is in this and what the half clamshell does? So volume in between cones comes out the front while volume in clamshells exits the back? This does have a smaller chamber dimension as it’s open at the top and bottom edge - so chamber depth is effectively half or 6in in this case.
Yes
Here is the back. The center slot is a traditional low volume SLOB (but pushed half way forwards).
There is a (assumed) metal shroud (half clam shell or is the part of the actual basket not punched out) on half of the back of the driver on the front of the speaker creating the half-chase that pushes the air behind the speaker. It is easy to overlook on first glance. Notice there are no holes between the magnet and the rim of the driver in front of the speaker like there is in the back of the speaker.
I would assume it resonants and could probably be built differently, while keeping the same small volume in front.
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That's why I only considered a pair at least its can be made into a normal looking bass bin perhaps with 45 cm width. Mids & too could be either horn or a 10or 12 inch FR like Lii Audio type.
Thks again
I installed the second channel with 8 of the GRS woofers to match the first channel. The bass is much deeper! I am on rev7 of the XO tweaks. It sounds absolutely spectacular now. Every genre kicks butt. Even speed metal is well resolved and absolutely clear. Metallica’s Blackened never sounded so good. The Voodooyoudo by Spyro Gyra just stuns me with how good it sounds. Some pop songs from a long time ago really sound great. I’ll try to make a new video clip soon. I think the crossover is about done.
XRX is a busy man so in case he's gone for a while here are some ideas:
The 10" only has Xmax = 2.8mm
The 8" is a classic weak motor high resonance OB woofer. Fs is good at 45Hz and should get pushed lower with the slot loading. Power at 25W is low but Xmax = 4.5mm will be quickly reached with the high QTs anyway. In multiples it could be OK depending on your SPL needs.
Keep the slot to 6" max dimension x, y and z and upper Hz will be useful.
I suspect the slot loading may color the lower mids with a horn timbre and could match well to a crossover to a horn.