Sealed Extremis

LAL · « **on:** 2 Nov 2005, 04:43 pm »

Kevin,
What is the effect of stuffing the ports of the Extremis woofers in the LCRs or making them in a sealed cabinet? Where does the the F3 lie in a sealed configuration? Any reason why this shouldn't work ok in situations where there is insufficient room for the rear vents to operate properly and a separate subwoofer is being used?

LAL

Kevin Haskins · « **Reply #1 on:** 2 Nov 2005, 04:55 pm »

You can run them sealed. In fact you can use a MUCH smaller enclosure if that is your plan. You just give up bandwidth. With the LCR if you just sealed off the ports your F3 would be around 70Hz and you would have a Q of round 0.55. A If you use a 15L-20L box for the two drivers you get a more desirable Q and a F3 of about 67Hz.

The Extremis parameters lend themselves more to ported alignments when unassisted electronically.

Carl V · « **Reply #2 on:** 2 Nov 2005, 08:13 pm »

Quote

With the LCR if you just sealed off the ports your F3 would be around 70Hz and you would have a Q of round 0.55. A If you use a 15L-20L box for the two drivers you get a more desirable Q and a F3 of about 67Hz.

I'll hazard a guess that the 'desirable" Q would be closer to .7?!
You're kinda on record to prefering the sound of .7

Kevin Haskins · « **Reply #3 on:** 2 Nov 2005, 08:54 pm »

Quote from: Carl V

Quote
With the LCR if you just sealed off the ports your F3 would be around 70Hz and you would have a Q of round 0.55. A If you use a 15L-20L box for the two drivers you get a more desirable Q and a F3 of about 67Hz.

I'll hazard a guess that the 'desirable" Q would be closer to .7?!
You're kinda on record to prefering the sound of .7

How did you guess.

I'm actually working on an active solution right now. I have the LT board designed to fit in our Hypex Amplifier chassis in front of the amplifier modules.

It allows us to use a VERY small enclosures and still get great bandwidth.

cOz · « **Reply #4 on:** 10 Nov 2005, 03:54 pm »

Wow an active solution would be awsome. That would really give people a reason to go with the Hypex amps. I think it would really simplify the building of the speakers too.

Kevin Haskins · « **Reply #5 on:** 10 Nov 2005, 04:59 pm »

Quote from: cOz

Wow an active solution would be awsome. That would really give people a reason to go with the Hypex amps. I think it would really simplify the building of the speakers too.

They can certainly be smaller. I'm hoping to show a prototype at CES.

Hardman · « **Reply #6 on:** 23 Nov 2005, 09:35 pm »

I am in the process of building a LCR for a friend and have been playing around with plugging the port. When the port is plug, in my room, it is very difficult to notice any difference. I have built a number of speakers in the past and this is the first time stuffing a port on a ported design had little impact on the LF extension. After reading Kevin’s comments above and then confirming the F3 in Unibox, I now wonder if maybe we are stuffing incorrectly (we used the 16 ounce bag of fill included in the kit – port is clear of fill).

Either we did something wrong, I am getting better in room response with a sealed port, or the LCR doesn’t really go as low as 35 Hz (again, I can barley notice the difference between a sealed or ported). One thing for sure, if a sealed LCR is 70 Hz, it is the best 70 Hz if have ever heard!

I guess the real reason I ask, is after building this speaker for my friend I now too want one. My setup lends to a smaller enclosure plus I have stereo subs. I just want to make sure I get he same results as a LCR sealed, when I build a 20L enclosure.

Kevin Haskins · « **Reply #7 on:** 23 Nov 2005, 09:52 pm »

The port is tuned low... about 30Hz so it doesn't contribute much up around the normal center channel cutoff. Make sure your processor is set to LARGE so you don't have some kind of high pass crossover in the mix. At the very lowest bass frequencies the port contributes a LOT of output.

Download the Real Traps test tone CD here:

http://www.realtraps.com/test-cd.htm

Play back the various tracks and you will see where the port contributes in comparison to the sealed box. Assuming everything has been assembled right you should get maximum port output around 30-33Hz. The Extremi will be moving very little but the port will have most of the output centered on the tuning frequency.

bald · « **Reply #8 on:** 24 Nov 2005, 12:59 am »

why not just front port the lcr?

bald

Hardman · « **Reply #9 on:** 24 Nov 2005, 01:05 am »

Good call on the test tones (I should have thought of that). I have a Cara test tone CD www.cara.de that I will use to do as you suggested. I am now in the process of finishing the outside of the speaker and as such it is apart. I will report back my results in a few days.

Kevin Haskins · « **Reply #10 on:** 24 Nov 2005, 04:28 am »

Quote from: bald

why not just front port the lcr?

bald

You can.... mine is with two 2" flared ports rather than the single 3" port. The front face has to be longer to fit the ports as they take up a lot of real estate.

The LCR is already a huge center channel. I've been focusing most of my energy on ways of making all the speaker models smaller while maintaining or even extending their bandwidth. The only way to do so is with active design features. Expect to see more early next year as I introduce some options for significantly decreasing the size of all the speaker models while maintaining their incredible bass performance.