After reading Mitch’s articles and watching his YT video I simply have to try it for myself.
Am using a GRS 10sw-4 ob in the trunk if my car. Is very efficient and am currently chasing rattles in the roof panels, goes very deep.
Hard to beat for $20 provided it serves your needs.
Hard to beat for $20 provided it serves your needs.
Just wanted to circle back to say I implemented a SLOB using 8x 6.5" per side (Dayton DC160-8) similar to xrk971's XSD, with great results. For now, without wings.
I'm still tweaking, but now xo at 70 and 400Hz (vs 80 and 300Hz with the naked 18"). Sounds much, much better. Midbass is a lot more impactful, meaty, yet fast as expected in OB. And goes easily to 400Hz vs the 18".
I will try with wings and see how it sounds down to 50 or 60Hz.
I also plan to try it up to 470Hz, the natural roll-off for the SLOB with chamber for the 6.5".
An additional bonus is the smaller footprint, which was not a goal I was pursuing, yet my wife appreciates it since they sit in the living room.
Thanks all for the food for thought along this thread!
I'm still tweaking, but now xo at 70 and 400Hz (vs 80 and 300Hz with the naked 18"). Sounds much, much better. Midbass is a lot more impactful, meaty, yet fast as expected in OB. And goes easily to 400Hz vs the 18".
I will try with wings and see how it sounds down to 50 or 60Hz.
I also plan to try it up to 470Hz, the natural roll-off for the SLOB with chamber for the 6.5".
An additional bonus is the smaller footprint, which was not a goal I was pursuing, yet my wife appreciates it since they sit in the living room.
Thanks all for the food for thought along this thread!
I recently had great success putting my diffusor panels directly behind my OB and moving my absorption to behind my chairs. Turns out I had over damped my room.. who woulda thought 😉
I did not. What do you mean by free air resonance, how should I measure it, and what will I learn from this?
On the majority of speaker specification listings, there is an entree called Fs. This is the free air resonance. This is basically the lower usable limit of a speaker driver. There are exceptions, but too complex for just this little essay. XRK uses a GRS driver with Fs of 69Hz w/ Qts of 0.87 ~~ This is actually quite clever. Why? Because when used in multiples in the mounting scheme that he does, the final group resonance drops down to about 50Hz. You can see it on his impedance plot. The decrease from 69 to 50 is greater than the typical shift. Along with that, the group Qts also increases. Both of these phenomena are the result of mutual coupling/mass loading since each driver is in close proximity to it's neighbor. This method, or mounting scheme that you and XRK have done is probably the most effective way to achieve bass from a di-pole radiating "speaker". There's a little bit more to this theory of operation but this is enough for now. It is quite the arduous task to examine the many available speaker drivers out there, to arrive at a candidate that is just right for the job. Having enough x-max is usually the compromised factor. The more advanced hobbyist who might be reading this will let there mind drift to the possibility of resorting to DSP the help raise the Qts function. It will be discovered right quick like this will be met with the aforementioned compromised amount of x-max. Having said that, I have found some prime candidates that are offered in a 12 inch size. They ain't cheap, and since this style project requires a total of 12 minimum (6-per side) the $$$$ get big real fast. With respect to measuring Free Air resonance, you can do a search and many methods will show up. Here's a link to one video, but the way he shows is not the only way. Congratulations on your progress over all these years. Best wishes, over & out.
I think what Scott L means is to use a DATS (or free version within REW) to sweep the speaker cones through frequency to see where the resonance is located. For a vented speaker, there will be two peaks and the valley in the middle is the Fs resonance frequency. For a dipole or open baffle, there will only be one peak and you take the peak value not the valley value. A slot loaded dipole will have a different response than a bare driver. For my XSD speaker in a SLOB, the impedance sweep shows the woofers resonance peak at 50Hz, despite the TS parameters saying that the free air resonance is 60’ish Hz. So the drop must be from the SLOB config. I am not sure it is from having multiple ones near each other though. It might have more to do with the slot imposing resistance to the free motion and reducing it.
Note the woofer peak is at 50Hz