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Port location for Belles with bass reflex


Stevenarrow

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Hello,

 

I've been listening to my custom 2-way Belles and am getting the urge to build a bass reflex box to go along with them. After a lot of drafting and research I think the best solution for me and my room is to build a top chamber to house the 510 horn and use that chamber as the bass reflex volume -- I have seen a couple guys do this with their LaScalas to maintain a stock look. I would like the same look, BUT I would like to port out the front so I can still have them close to the rear wall in my apartment.

 

Is there any issue with bass porting close the a full range horn? Please take a look at the elevation drawing of the proposed solution. The ports would be at the edges of the enclosure and would be heavily braced. The edge of the horn is 6" from the port. I'm not sure if the air between the two would interact negatively.

 

just for reference, here is a link to my Belle build. https://community.klipsch.com/index.php?/topic/150730-2-way-summer-project-belle-build/page-4?hl=summer

 

Thoughts?

 

 

post-58443-0-92560000-1420217345_thumb.j

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large port openings on either side of the K510 would likely be advantageous as they would provide a sort of trap for horizontal horn radiation. I would not guess that the port radiation would be near close enough to impact the K510 given the compression ration of the driver used. I am sure that Dennis would have some insight into this. Lets hope that he responds. Best regards Moray James.

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I would open the doghouse up on the top into a sealed HF chamber. The total volume of doghouse plus the upper chamber would be roughly 110 litres. The ports would then be on the front of the top chamber. The 510/horn would remain a seal, self contained unit.

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After a few 'rough' calculations in WinISD...

 

If I tune the ports to 38Hz, I should gain roughly 10dB at that tuning frequency. Which results in two ports 8"x1.5" and 7"deep. These dimensions jive with the port calculations posted in most of the LaScala bass reflex mod posts.  

 

Adding a further extra 60 litres (170 total) gives slightly more bass volume but with a steeper roll off. So, it seems simply adding  the HF chamber works pretty well for the Kappa 15C driver I am using.

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The 4pi two way design by Wayne Parnham has an offset horn and one side of the horn is to the cabinet edge while the other is right next to the port, I recall Wayne discussing the fact that the vent opening was a good way to lose direct reflections from the horn (off of the baffle). You could contact Wayne at his site on the forum he is very approachable and very particular when it comes to details. I expect that you will be very pleased with your build. As I see it the riser mod is about as close to a free lunch as it gets in this world. Best regards Moray James.

http://www.pispeakers.com/contents.html

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I've not seen your initial thoughts of the K510 (direct me if they're out there and I'll be happy to go read if the next isn't redundant)

 

What are your thoughts of going 2-way?

 

I'm going to guess that "it doesn't suck" would be an acceptable comment?

 

:)

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The 4pi two way design by Wayne Parnham has an offset horn and one side of the horn is to the cabinet edge while the other is right next to the port, I recall Wayne discussing the fact that the vent opening was a good way to lose direct reflections from the horn (off of the baffle). You could contact Wayne at his site on the forum he is very approachable and very particular when it comes to details. I expect that you will be very pleased with your build. As I see it the riser mod is about as close to a free lunch as it gets in this world. Best regards Moray James.

http://www.pispeakers.com/contents.html

 

Thanks Moray. I'll look into the pi speaker.

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I've not seen your initial thoughts of the K510 (direct me if they're out there and I'll be happy to go read if the next isn't redundant)

 

What are your thoughts of going 2-way?

 

I'm going to guess that "it doesn't suck" would be an acceptable comment?

 

:)

 

I do not have very much experience with horns and driver combos, so take my comments with an amateur's point to view. 

 

I have not heard a 3-way system that is as coherent as a 2-way without spending a TON of money. My friend has $9K 3-way speakers (direct radiators) that are fantastic in that regards. The 2-way system has much more focus to the centre image than any 3-way at this price range. There simply is no contest for razor sharp centre image and placement of musicians left to right within the sound stage. With not having a tweeter, I do not detect any loss of detail or high end information through the rest of my equipment*. If I were to start again from scratch for any build, I would consider the simpler crossover and lack of tweeter as budget surplus to spend on 'full-range' horn and driver.

 

The 510 does not suck. Again without a ton of experience and no 'double blind' testing, the 510 sounds awesome and huge in my apartment. It is huge; near floor to ceiling presentation. Very efficient. Great dynamics. I fear there may be a little thinness in the lowest mid range. I am quite happy with the horn.

 

 

*the rest of my equipment:

Grace F9 w/ Soundsmith Ruby-OCL

VPI Classic

Leben RS30-eq

Leben CS-600

2way modern Belles

Edited by Stevenarrow
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It won't be -6db @ 40hz if you port it. This is an excellent concept. The porting will cause a little loss of efficiency in the bass, the high end will need to be dropped a little to get the tonal balance right, but you would have to work on that anyway.

Bruce

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Stevenarrow:  I'm new to the site.... love what your doing with the Belles.  I am really interested to see how your ports work out and if you get substantial bass extension. I am planning to start my own set within a month or two, hope you don't mind if I follow along.

First time I have seen anyone doing this with belles and taking it to top hat. Good luck and tear it up!

 

Rob

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Stevenarrow:  I'm new to the site.... love what your doing with the Belles.  I am really interested to see how your ports work out and if you get substantial bass extension. I am planning to start my own set within a month or two, hope you don't mind if I follow along.

First time I have seen anyone doing this with belles and taking it to top hat. Good luck and tear it up!

 

Rob

\

Rob the vented riser mod is a well established modification which can be added to the cavity that the horns are mounted in or in a similar size riser under the speaker. The mod was developed by forum member DJK and there are numerous threads in the archive if you wish to research them. Best regards Moray James.

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Stevenarrow:  I'm new to the site.... love what your doing with the Belles.  I am really interested to see how your ports work out and if you get substantial bass extension. I am planning to start my own set within a month or two, hope you don't mind if I follow along.

First time I have seen anyone doing this with belles and taking it to top hat. Good luck and tear it up!

 

Rob

 

let me know if you need any drawings or spec's... pretty sure most everything has been posted. My Belles are a little different than standard, just enough to make them fell a little more modern in look.

 

I gotta say, I have experience with LaScalas, and the Belles (with braces and heavy baffles) have ZERO resonance in the side panels...Makes a difference: the large side panels are much stiffer.

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