Front Porting / Modifying the LCR

kfr01 · « **on:** 3 May 2005, 04:19 am »

Kevin, others:

A friend and I have been so impressed with the Kit61 we're both contemplating 3 LCR speakers across the front of our home theaters.

I'm redoing my basement and planning on using a front projector. My friend has a slightly larger room he already has a front projector in. We don't want the speakers sticking out into the room. So, we're very interested in a workable front-ported LCR design.

We are contemplating two different options:

1) Increase the L and R to 261 size towers. Decrease tuning frequency and slightly increase volume. Use the extra front baffle real-estate to move the front port here.

or

2) Keep the same alignment as the original LCR (tuning freq. + volume), making towers out of the L and R, moving the port to the front, but this time using extra bracing, etc. to keep the same volume.

And this leaves us wondering what to do with the center. Slot ports using the original LCR tuning freq. + volume? If we went with the modified 261 volume and tuning frequency would we change the center to match?

I started posting on this in the soundillusions forum, but this seemed like a more appropriate forum for a dedicated thread on this topic.

Anyway, we're just looking for the ideal solution.

kfr01 · « **Reply #1 on:** 3 May 2005, 04:48 am »

Quick idea on the center: is it possible to side-port the center? The 7 3/4" wall between the rear of the speaker and the brace is large enough for the stock port. Any problems with having the port perpendicular to the speakers at all? I can't find anything about it in my "loudspeaker cookbook," looking for actual experience here.

Kevin P · « **Reply #2 on:** 3 May 2005, 02:52 pm »

If you think the KIT61 is impressive just wait until you hear a LCR.

I've been talking with Dan about this very subject. Porting a center out the rear can cause a lot of problems when trying to fit it in an install.

The best solution I've seen so far is a slot port out the front. I've yet to build a slot ported version though. A pair of Extremisis needs a very well designed port or you get chuffing so we are going to try building one before we release plans for it.

Just using the LCR sealed is another option. A pair of the 6.8s sealed only needs about 0.5ft^3 so the speaker could be significantly smaller in depth. You loose some of the low frequency performance though and nobody wants that!

I'd just hold tight until we get our slot port design published. Changing the front baffle dimensions more than 5% or so results in real problems.

kfr01 · « **Reply #3 on:** 3 May 2005, 03:44 pm »

Quote from: Kevin P

If you think the KIT61 is impressive just wait until you hear a LCR.

I've been talking with Dan about this very subject. Porting a center out the rear can cause a lot of problems when trying to fit it in an install.

The best solution I've seen so far is a slot port out the front. I've yet to build a slot ported version though. A pair of Extremisis needs a very well designed port or you get chuffing so we are going to try building one before we release plans for it.

Just using the LCR se ...

Awesome, I'm glad to hear a that you're releasing that design! I think more HT folks will be willing to try the design w/ a front port.

Kevin P · « **Reply #4 on:** 3 May 2005, 04:20 pm »

Quote from: kfr01

Awesome, I'm glad to hear a that you're releasing that design! I think more HT folks will be willing to try the design w/ a front port.

The LCR is too large for most sane people.

But hey.... who is sane in this hobby?

kfr01 · « **Reply #5 on:** 5 May 2005, 04:08 pm »

Quote from: Kevin P

Quote from: kfr01
Awesome, I'm glad to hear a that you're releasing that design! I think more HT folks will be willing to try the design w/ a front port.

The LCR is too large for most sane people. But hey.... who is sane in this hobby?

lol, no one is sane in this hobby. And I have to say, listening to the Kit61 makes folks go insane very fast. Everyone I've had over to listen to them is suddenly thinking about upgrading their speakers. Their wives/girlfriends all hate me now.

Anyway, the speaker discount sounds great too. Once I get some more free-time to work on speakers (and if we can get the slot front thing figured out) I'll probably be making an order of 3.

Kevin P · « **Reply #6 on:** 5 May 2005, 04:48 pm »

I had some time to work on this last night. Two 2.5" round ports which can be made from PVC will work and should provide more than enough port area to prevent chuffing. They also will fit on the front panel wihtout having to change baffle dimensions. With a 1.5 ft^3 enclousre the two 2.5" round ports would have to be 11.5" long to tune the enclosure to 33HZ. It's nice to cut the hole for the ports and provide a nice round-over to help both cosmetically and with the port compression issues.

Round ports make building the cabinet easier than doing a slot port but I have a slot port designed on a napkin for those who are interested in going that route.

RAW · « **Reply #7 on:** 5 May 2005, 05:31 pm »

How about CNC front baffles and magnet grills. 1"MDF
We are going to have CNC cut baffles and magnetic grills to match ,1.5" more in width so those doing cabinets can do a round over on the edges as the tweeter is very close to the corner.
Dan said this extra width in the baffle as they will be used rounded over with 3/4" will not effect the crossover at all.

As well as CNC 61 baffles and grills 3/4"MDF
This will help the kit builders that just want to build a box and have grills.
And the magnets to boot that once veneered do not show at all is sweet.

kfr01 · « **Reply #8 on:** 5 May 2005, 05:57 pm »

Kevin: I'm glad those ports fit! Nice. Some friends of mine and I are interested in seeing both of those designs once you finish them up.

Raw: That's an excellent idea. I found that the front baffle was easily the hardest / toughest part of the speaker for speaker building newbies such as myself. I'd especially be interested in the LCR baffle because of the increased number of drivers and their close proximity to one another. Keep us updated on this!

The magnet grill thing sound good too. I built my Kit61 without grills, as we have no kids at the moment, but I see that situation changing in the next handful of years. It'd be nice to throw some grills on to block little hands.

bald · « **Reply #9 on:** 6 May 2005, 03:17 am »

Finally got registered on this board (no thanks to the admins - this board registration process has some serious setup issues) to voice more support for a front ported LCR. I am very interested in a set of 3 lcr's for the L/C/R of my front projection setup, and will try to get together the money to take advantage of the discounts you are offering.

I am also excited about the CNC cut front baffle, as that will get me listening to the LCRs that much faster

. I have some energy speakers currently, and I think magnetic grill covers should be standard on any speaker with a grill.

Look very forward to hearing more about the dual front ported / slot ported lcr. Thanks for all your hard work

bald

Kevin P · « **Reply #10 on:** 6 May 2005, 05:43 am »

Quote from: RAW

How about CNC front baffles and magnet grills. 1"MDF
We are going to have CNC cut baffles and magnetic grills to match ,1.5" more in width so those doing cabinets can do a round over on the edges as the tweeter is very close to the corner.
Dan said this extra width in the baffle as they will be used rounded over with 3/4" will not effect the crossover at all.

As well as CNC 61 baffles and grills 3/4"MDF
This will help the kit builders that just want to build a box and have grills.
And the magnets to boot that once veneered do not show at all is sweet.

Ok Al.... way to go. Now I got to lay out another couple thousand bucks to buy baffles & grills! Do you know how much I have sunk into this project?

All kidding aside.... I think it's a great idea. I'd like to see a stable final design before we jump on a couple hundred CNC cut baffles but the idea has merit. I've already got three different cabinet designs for the same speaker so we have to determine which one to go with. I think the front ported version with the round ports makes the most sense but I'm open to customer input. There is no way we can stock three different front baffles for one speaker design.

Kevin P · « **Reply #11 on:** 6 May 2005, 05:46 am »

Quote from: bald

Finally got registered on this board (no thanks to the admins - this board registration process has some serious setup issues) to voice more support for a front ported LCR. I am very interested in a set of 3 lcr's for the L/C/R of my front projection setup, and will try to get together the money to take advantage of the discounts you are offering.

I am also excited about the CNC cut front baffle, as that will get me listening to the LCRs that much faster . I have some energy speakers currently, and I ...

Welcome to the Circle. Usually the admin is pretty good around here. I'm sure all forums have their glitches.

RAW · « **Reply #12 on:** 6 May 2005, 02:11 pm »

Forgot that your money tree is needing a little watering.
Mine is close to the sahara maybe we can share some water.

Yes as Kevin noted.
Kevin has been doing work on the front baffles for front porting the designs.In Cad
And the front baffles of the LCR is by far the most work to layout and make.

Those who want the baffles and grills can conact me as we have them coming for the 61,261,LCR all will have magnetic front grills installed
The LCR will be 1" and all others will be 3/4"

People do not think I am working agianst Kevin as I am trying to help out with the baffles and cabinets for those wanting to make the DIY a little easier.

Plus makes the E kits a lot easier to build.And the wife would like the grills