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KLF-30 Redesign


Breck

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Good luck on the design.  

 

I would be considering adding some volume to a KLF 30 vs removing.  Since the ports are to the rear, you wouldn't notice the mid-range bleed through unless you specifically tested for it with everything else turned off.  The fact that they are in the back and minimal enclosure stuffing will tell you right there though sometimes that bleed through can make the speaker more appealing.

 

If you are dropping the size, you will be dropping the port size or making them longer.  If the ports are facing the floor then that will be helpful in removing any unwanted wind noise or mid output.  

 

You must be going to use these with a sub, correct?  The 30s don't get super deep as it is with their small enclosure.

 

I would be looking at larger enclosure with somewhat lowered tuning, and if you are doing a crossover, adding an 8" mid bass or possibly 2 6" to clean up the discontinuity between the mid horn and the woofers.  That would address the KLF 30's weak points.

They get a lot deeper if you remove the feet and put the cabinet directly on the floor.

 

You have to be careful here, it depends on the floor and how much is room induced resonances. It may work well for you depending though.  Also those resonances take time to dissipate so you will typically lose definition unless you are on a 6" slab. Now if you can make the speakers weigh as much as a truck then that would sure tighten things up  :o

My home builts using 2 KLF20 woofers a side weigh in at about 250 lbs each.  They are fine sitting on the carpet and that works well.  The KLF30s sitting next to them, not so much on the carpet.

 

If these updated KLFs are double thickness and braced well, tuned correctly (a nice trough in the impedance where the resonant frequency of the woofers is - ports appropriate size to supplement the bass), they will likely sound very tight with excellent extension.  No nasty's from the cabinet.

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A box is a box is a box. They all sound alike.

when they are all simply empty boxes or when they have been poorly modified I would tend to agree but if they are properly designed and braced and damped they can sound very good. Open baffle is great I agree but open baffle bass does not pressurize the room. I ran electrostatic dipoles for close to 25 years so I have some experience with open baffle loudspeakers. Last October at the Toronto Consumer Electronics Show The room I was with won five best sound at show awards we were running open baffle loudspeakers. I like my reflex loaded cabinets that I have right now running with Karlaon K-Tube loaded EV DH1A compression drivers and I would not trade those out any time soon.. Edited by moray james
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Open baffle is great I agree but open baffle bass does not pressurize the room.

 

Yeah...I almost went that way but the bass.......I wonder if subs would work well with open baffle designs? Maybe even better? :unsure2:

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Added 3/4" to the interior with center brace

Have you modeled the woofers with that much volume gone?  What is your interior volume after removing about 1 cubic foot or so?  It appears you are raising the box frequency dramatically.

If you are using a sub for the low bass and/or not using the KLF-30 woofers, you will likely be ok.  If not you will have an interesting proposition on your hands.

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Open baffle is great I agree but open baffle bass does not pressurize the room.

 

Yeah...I almost went that way but the bass.......I wonder if subs would work well with open baffle designs? Maybe even better? :unsure2:

 

Mine do. ;)..... Sorry for the thread jack Breck. :(

Edited by cradeldorf
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Added 3/4" to the interior with center brace

Have you modeled the woofers with that much volume gone?  What is your interior volume after removing about 1 cubic foot or so?  It appears you are raising the box frequency dramatically.

If you are using a sub for the low bass and/or not using the KLF-30 woofers, you will likely be ok.  If not you will have an interesting proposition on your hands.

While I am sure that you are very happy with your speakers it would be much more productive if you kept on topic. You speakers are not a conventional open baffle loudspeaker. Both of your woofers are loaded by a box, thought you did not like boxes?

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Added 3/4" to the interior with center brace

Have you modeled the woofers with that much volume gone?  What is your interior volume after removing about 1 cubic foot or so?  It appears you are raising the box frequency dramatically.

If you are using a sub for the low bass and/or not using the KLF-30 woofers, you will likely be ok.  If not you will have an interesting proposition on your hands.

According to my calculations the added interior thickness and bracing removes .9 cubic feet. With the acoustic dampening that I will be using will add roughly .5 cubic feet, for a net loss of .4 cubic feet. Negligible in my opinion. With proper tuning I think it will be fine.

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attachicon.gifimage.jpgattachicon.gifimage.jpg

Added 3/4" to the interior with center brace

Have you modeled the woofers with that much volume gone?  What is your interior volume after removing about 1 cubic foot or so?  It appears you are raising the box frequency dramatically.

If you are using a sub for the low bass and/or not using the KLF-30 woofers, you will likely be ok.  If not you will have an interesting proposition on your hands.

According to my calculations the added interior thickness and bracing removes .9 cubic feet. With the acoustic dampening that I will be using will add roughly .5 cubic feet, for a net loss of .4 cubic feet. Negligible in my opinion. With proper tuning I think it will be fine.

 

How did you come up with that you will get .5 cf back from dampening material?  Have you found some type of calculator for that?  

I believe that typical dampening can add maybe up to 10% in a bass reflex box but that is debatable (more in sealed enclosures).  Some say you may raise the tuning a tad.  You will need to measure.  Typical use of the filling is to stop internal reflections in the box.

I find a box of the appropriate size designed correctly to minimize box resonance and using lower amounts of dampening material (not stuffed) will be much more punch, extend lower, and provide cleaner bass.

If dampening could solve the volume problem, Klipsch would have dumped more in the Cornwall and definitely in the KLF-30 since the woofers are tuned much lower than the small box they are in allows.

 

Breck, you might like the results but don't look for more low bottom end from your changes.  I would like to be wrong on this statement because I would like to build smaller boxes.  

 

Please test your system when done.  I'd like to see electrically if the resonant point has been moved lower.

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Ah, some additional information:

http://www.data-bass.com/data?page=content&id=79

 

It appears the actual resonant point moves lower but there is also a substantial output loss / efficiency loss from the stuffing.  That may be why I thought the systems I've dealt with were less punchy.

 

The funny thing I notice about the charts is that there is no real gain from stuffing, only losses.  You are able to push the resonant frequency down but there is no gain to overall system response because of:

1 - lowered efficiency

2.- the response curve likely due to the box size does not extend lower.

 

Reducing the size and attempting to gain the volume back with stuffing appears not to be 1 to 1.  As the old adage says, no replacement for displacement.

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