What kind of enclosure is this? And basic question on TL and L-slot enclosures

[arjunm009]

Hi
I found this speaker from Grovemade.

I would like to know if this a Transmission Line enclosure?

If so, shouldn't this be stuffed with damping materials? What is the purpose of those grooves and steps you see in Label C and Label B? Is it just for aesthetics or it does in some manner contribute acoustically?


Question regarding Transmission Line.

I read this article where the author says not all drivers are suitable and one should make the choice based off its Qts and Qtc parameters. But doesn't go on details what precisely?
So what kind of drivers can I use? What parameters am I suppose to look at? Is there any handy guide?


Question regarding L-Slotted enclosure.
Is this a special kind of TL enclosure if one goes by this guide about TL enclosure designs marked as Folded Straight Line?

Otherwise, does this enclosure type also have any specific driver type preference?



I mostly have full range drivers at my disposal. I am looking forward to experiment with these type of enclosures because this would be my first attempt with them.
Now to give an idea what kind of drivers I have, here are 3 of them

Dayton CE52P, Fountek FR58EX, Dayton ND91-8

 

[xrk971]

I think it is a bass vented reflex (BVR). There is a mild amount of bass gain from the expanding vent at the end, but nothing as much as a BLH would give. Also, the bass extension is determined mostly by the reflex volume and vent dia x length, and not the length of the expanding waveguide at the end of the vent.

 

[GM]

I think it is a bass vented reflex (BVR).

Right, though BVR = big vent reflex which was originally called a port horn for use with corner loaded reflex cabs. It was basically an 1/8 WL parabolic stub since it was just a slanted board shelf vent.

This one OTOH is a two stage vent and when done right can be pretty impressive as proven by Scott[moose's] various BVR alignments.

GM

 

[Ugg10]

The grooves I suspect are just there because they used a fairly large ball nose cutter in the CNC machine they used to make it and didn’t bother to do a second pass with a smaller cutter to smooth it off. They may have also thought that the rough surface may reduce standing waves/reflection but I doubt that that would make any audible difference in reality.

Looking at the website, the stand/grill for the driver is more of an issue unless again it is designed to act as a passive pad to reduce the mid/high volume compared to the bass from the port.

Also the specs claim of 20-20khz I think is a tad over ambitious. Uses a $20 FR58EX driver to quite a bit of margine. Spec also claims a back loaded horn design.

 

[picowallspeaker]

The grooves I suspect are just there because they used a fairly large ball nose cutter in the CNC machine they used to make it and didn’t bother to do a second pass with a smaller cutter to smooth it off. They may have also thought that the rough surface may reduce standing waves/reflection but I doubt that that would make any audible difference in reality.
So why worry ???
Looking at the website, the stand/grill for the driver is more of an issue unless again it is designed to act as a passive pad to reduce the mid/high volume compared to the bass from the port.
Yes, that's an acoustic adaptor, not a grill!

Also the specs claim of 20-20khz I think is a tad over ambitious. Uses a $20 FR58EX driver to quite a bit of margine. Spec also claims a back loaded horn design.

20 Hz @-20 dB and 20 kHz @-15 dB

 

[grahamgraham]

The texture on the port section looks like it will only encourage turbulence IMO.

 

[arjunm009]

I think it is a bass vented reflex (BVR). There is a mild amount of bass gain from the expanding vent at the end, but nothing as much as a BLH would give. Also, the bass extension is determined mostly by the reflex volume and vent dia x length, and not the length of the expanding waveguide at the end of the vent.

Are there any softwares to help calculate how to build these type of enclosures?

 

[arjunm009]

The grooves I suspect are just there because they used a fairly large ball nose cutter in the CNC machine they used to make it and didn’t bother to do a second pass with a smaller cutter to smooth it off. They may have also thought that the rough surface may reduce standing waves/reflection but I doubt that that would make any audible difference in reality.

I was further researching about these and I found a video revew where it was said it is modeled like a concert hall without parallel walls and flat surfaces which help reduce distortion.


I was wondering if I built an enclosure in cylindrical or penta or hex sides, do they also help in reducing distortion. How much of a difference would that have comparing a rectangular box?

 

[xrk971]

Are there any softwares to help calculate how to build these type of enclosures?

I use Akabak and it’s a 3 segment problem - very easy. Chamber-Channel-Vent. Driver on chamber with front radiator element and radiator element on vent.

I’m sure other software like MJK mathcad worksheets can do it as well.

Yes, “Big” not Bass Vent Reflex.

 

[GM]

HornResp also:

GM