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Port location for Belles with bass reflex


Stevenarrow
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Steven:  Man your construction is getting me all pumped up!  Got the tube amp and the table saw so no more excuses!  

 

Are you using stock Belle dimensions other than the 1" up grade. When you increased the bass cabinet wall thickness to 1" you accounted for that dimensionally. Are you making the top cabinet the same width and depth as the bottom? I would love to see the dimensional drawings to account for the 1" material if you don't mind sharing. 

 

I'll have to account for the mid horn and tweeter between the ports on my build, are you still planning a two way system?

 

Great idea on the the braces.  Did you use screws on the base bins or just glue it up under pressure?

 

Stay strong in your resolve!

 

Rob

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Rob,

 

Yes. All important internal dimension are stock Belle. I did alter the way the doghouse joins at the front to avoid the hard edge lip. I also increased the dimension towards the outside to make up for the 1" frame material.

 

The top cab will be the same width and depth. I am making the internal height dimension 10 1/4" to fit the K510 horn -- I will not go back to a 3-way, so YES, it will stay a 2-way.

 

The braces were all custom cut to fit precisely (they required very minor adjustments to fit tight). They are were glued and fit under pressure (sand bags and clamps) as the last item to be installed. The braces are required for best bass sound.

 

Please see attached stock Belle dimension plans and a brief Custom set that outlines my changes.

Belle_Custom.pdf

Belle_LATEST.pdf

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"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"

 

Actually, not.

 

The huge peak at 140hz goes down, and the dip at 200hz comes up.

 

VentedBelle_zpsa46256ea.jpg

 

Tuned to 35hz, uses EV Inteface A EQ (+6dB at 35hz), flat to 32hz (in room).

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When you think about it, porting must actually increase the overall efficiency since the backwave of the bass driver is now being summed with the forward wave--like a bass reflex design, whereas in a typical Belle or La Scala bass bin, the backwave is used only as an air spring and damper--like in an acoustic suspension loudspeaker. 

 

What does change is the overall frequency response of the bass bin which usually must be re-equalized (re-EQed) by a crossover/balancing network, active digital crossover, and/or dedicated equalizer.  I assume that's what Bruce is referring to.

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It sounds different (in a good way).


 


The mid and HF levels on most Klipsch speakers seem a bit 'hot' anyway.


 


The closer you can get the match between the drivers at the crossover point (s), the better things sound (anyway).


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  • 1 month later...
  • 1 month later...

 

Any updates on the riser mod results ?

Thanks

 

They are coming along slowly. should be up and running shortly though.

 

I'm almost done with my belle bassbins (I plan on using kappa 15c too).

Did you need to rabbet out the motorboard near the surround to prevent the cone from slapping into it? That's what I've been advised on http://www.diyaudio.com/forums/subwoofers/268959-zobsky-contemplates-variation-belle-klipsch-4.html

Edited by zobsky
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Any updates on the riser mod results ?

Thanks

 

They are coming along slowly. should be up and running shortly though.

 

I'm almost done with my belle bassbins (I plan on using kappa 15c too).

Did you need to rabbet out the motorboard near the surround to prevent the cone from slapping into it? That's what I've been advised on http://www.diyaudio.com/forums/subwoofers/268959-zobsky-contemplates-variation-belle-klipsch-4.html

 

 

I did not have to do that. The Kappa was a drop-in replacement. Sounds great.

 

I am still not finished my bins. I have been working too much, been partying too much, been working on other projects too much; and I am lazy.

 

That said, I'm love the 2-way Belle, not sure how it could get that much better.

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Stevenarrow: what kind of frequency response are you getting with the Kappa 15c? I am most interested in what the top end range looks like and what extension you are getting. Some members are looking at the University Classic and I am wondering what new driver might provide enough extension to make for a simple two way speaker that digs deep yet extends far enough to make matching up to domestically sized horns a possibility. Not unlike your project only a larger bass horn. Best regards Moray James..

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"There is going to be a downside to the reflex ports, my understanding is when ever you let sound from the front AND rear of a radiator interact the result is a muddier sound. (due to different path lengths of the 2 sound sources)"

 

Man, there are sure gonna be a lot of Cornwalls out at the curb for the trash collector tomorrow!

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Stevenarrow: what kind of frequency response are you getting with the Kappa 15c? I am most interested in what the top end range looks like and what extension you are getting. Some members are looking at the University Classic and I am wondering what new driver might provide enough extension to make for a simple two way speaker that digs deep yet extends far enough to make matching up to domestically sized horns a possibility. Not unlike your project only a larger bass horn. Best regards Moray James..

I'll get out my microphone and test set up this weekend and do a low end sweep for you. Feel free to remind me if it slips my mind.  My ears tell me that the Kappa and the 510 match up pretty decent. And the HipHop records (Dimond District - March on Washington (Recommended)) tells me they go pretty low in the braced Belles. The braces are very recommended.

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"There is going to be a downside to the reflex ports, my understanding is when ever you let sound from the front AND rear of a radiator interact the result is a muddier sound. (due to different path lengths of the 2 sound sources)"

 

Man, there are sure gonna be a lot of Cornwalls out at the curb for the trash collector tomorrow!

I've heard ported La Scalas. There is no going back to stock. That said, The LaScals were stock frame and stock driver. I think a 1" box and brace side baffle cleans up the low end quite a bit. Great thing is the port mod is reversible -- and alterable. If it gets a little muddy, one can always try aperiodic loading to tighten the sound and the expense of the lowest rumble.

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Stevenarrow: what kind of frequency response are you getting with the Kappa 15c? I am most interested in what the top end range looks like and what extension you are getting. Some members are looking at the University Classic and I am wondering what new driver might provide enough extension to make for a simple two way speaker that digs deep yet extends far enough to make matching up to domestically sized horns a possibility. Not unlike your project only a larger bass horn. Best regards Moray James..

 

The Kappa in my Belle starts to drop a lot after 400z. It is only about -3dB at 50 and drops fat below that. It is clean and clear at 30hz, but just not very loud.

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Stevenarrow: what kind of frequency response are you getting with the Kappa 15c? I am most interested in what the top end range looks like and what extension you are getting. Some members are looking at the University Classic and I am wondering what new driver might provide enough extension to make for a simple two way speaker that digs deep yet extends far enough to make matching up to domestically sized horns a possibility. Not unlike your project only a larger bass horn. Best regards Moray James..

 

The Kappa in my Belle starts to drop a lot after 400z. It is only about -3dB at 50 and drops fat below that. It is clean and clear at 30hz, but just not very loud.

So are you planning to stick with the Kappa or are you going to use a driver with less travel and a lighter cone to get response up past 400 Hz?

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