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What kind of enclosure is this? And basic question on TL and L-slot enclosures
What kind of enclosure is this? And basic question on TL and L-slot enclosures
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Old 11th October 2018, 05:31 PM   #1
arjunm009 is offline arjunm009
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Default What kind of enclosure is this? And basic question on TL and L-slot enclosures

Hi
I found this speaker from Grovemade.

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

Click the image to open in full size.

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?

Click the image to open in full size.

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

Last edited by arjunm009; 11th October 2018 at 05:34 PM.
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Old 11th October 2018, 06:01 PM   #2
xrk971 is offline xrk971  United States
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What kind of enclosure is this? And basic question on TL and L-slot enclosures
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.
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Old 12th October 2018, 05:36 AM   #3
GM is offline GM  United States
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Originally Posted by xrk971 View Post
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.

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Old 12th October 2018, 07:06 AM   #4
Ugg10 is offline Ugg10  United Kingdom
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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.

Last edited by Ugg10; 12th October 2018 at 07:14 AM.
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Old 12th October 2018, 07:41 AM   #5
picowallspeaker is offline picowallspeaker  Italy
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Quote:
Originally Posted by Ugg10 View Post
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 didnít 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
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Old 12th October 2018, 07:58 AM   #6
grahamgraham is offline grahamgraham  United Kingdom
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The texture on the port section looks like it will only encourage turbulence IMO.
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Old 12th October 2018, 02:07 PM   #7
arjunm009 is offline arjunm009
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Quote:
Originally Posted by xrk971 View Post
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?
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Old 12th October 2018, 02:13 PM   #8
arjunm009 is offline arjunm009
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Quote:
Originally Posted by Ugg10 View Post
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 didnít 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?
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Old 12th October 2018, 03:24 PM   #9
xrk971 is offline xrk971  United States
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What kind of enclosure is this? And basic question on TL and L-slot enclosures
Quote:
Originally Posted by arjunm009 View Post
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.
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Old 12th October 2018, 07:51 PM   #10
GM is offline GM  United States
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HornResp also:

GM
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