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Old 06-12-2014, 10:49 PM
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Quote:
Originally Posted by LTD02 View Post
after re-reading your post a few times, I suspect that most of your questions are answered by knowing that at subwoofer frequencies, the sound is not directional and "beaming" as you have presented it in your pictures, but extends from the subs more as concentric circles with the sound reflecting off the walls and ceiling as though you inflated a giant balloon at the point of your subwoofer.


there will not be a null in between the subs. the spl with the drivers aimed sideways or forward will vary a bit, but more from things like 1/4 wave reflections off the rear wall for forward mounted drivers. the direction of the port matters very little as the bass wave at 20hz for example is 56.5 feet long, so it is "everywhere" in the room even before it has left the subwoofer.


i would suggest trying to find an enclosure design that keep the port to about 36-40" or so but that can be pushed if these are mostly movie spl machines. the concern is the first port resonance. that can get close to the passband if the ports get too long.
Could someone explain what LDT02 is talking about "the concern is the first port resonance. that can get close to the passband if the ports get too long." I was just trying to get the parameters in the port velocity tab to stay reasonably close to what I saw in WinISD for Marty Cube and Mini Marty. I noticed it said that the port resonance was at about 129 Hz but assumed that this would be above by the preamp's crossover around 90 Hz and not relevant as long as I stayed above the crossover slope.

Also, I am concerned about tight response for these subs to integrate them with my Martin Logans. I didn't think of them as "SPL machines for Movies" as we don't play the electrostats at ear splitting levels. I did want them to be able to produce a tangible punch for LFE special effects even though I have a large room. I was under the impression that you can reproduce deep bass without needing every frequency to be at 125db.

What port size and length would LDT02 recommend for an approx 8 cu ft sub with these 29" x 24" x 32" dimensions?
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Old 06-12-2014, 10:51 PM
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Nice work John, that really helped explain how to do it a LOT easier for me...lol


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Old 06-13-2014, 05:42 AM
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Nice work John, that really helped explain how to do it a LOT easier for me...lol


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That looks really awesome! You did a great job with your subs and I like how they are the same height as the JTR speakers on stands. Attention to detail is something that I pay attention to way too much! Haha. Great job!
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Old 06-13-2014, 06:50 AM
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Nice work John, that really helped explain how to do it a LOT easier for me...lol


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Are those four SI-24's?
If so you have a huge amount of SPL capability.

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Old 06-13-2014, 09:19 AM
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Originally Posted by AV Science Sales 5 View Post
Are those four SI-24's?
If so you have a huge amount of SPL capability.


No they are four UXL-18's in 13cu/ft ported cabinets with a port tune of 14-15hz, don't worry I still have a huge amount of SPL capability though...lol
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Old 06-13-2014, 01:19 PM
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No they are four UXL-18's in 13cu/ft ported cabinets with a port tune of 14-15hz, don't worry I still have a huge amount of SPL capability though...lol
Do they modulate the screen at high SPL?
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Old 06-13-2014, 07:43 PM
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Do they modulate the screen at high SPL?

Not for movie use, but if I play certain bass track songs like "Bass I Love You" yeah, I can make it bounce like a trampoline....lol


I'm never noticed it with movies, even when knowing a big bass scene is coming up and looking for it.
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Old 06-13-2014, 07:58 PM
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I just put first coat of finish on my minimarty with uxl18.

And


After I am done with the finish I will take better pics. Tomorrow I start piecing together the video.
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Old 06-13-2014, 08:59 PM
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Wow did that ever turn out awesome Donny! So far I think that's the nicest finish you've done
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Old 06-13-2014, 09:11 PM
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Thanks,
Teak is pricey , but very classy.
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Old 06-13-2014, 09:22 PM
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Thanks,
Teak is pricey , but very classy.


I agree, I have some nice patio furniture that's teak.
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Old 06-13-2014, 10:14 PM
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I agree, I have some nice patio furniture that's teak.
Congrats on getting all four up and running! Curious if you have considered placing two in the rear corners of the room?
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Old 06-13-2014, 10:21 PM
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Congrats on getting all four up and running! Curious if you have considered placing two in the rear corners of the room?
They would never fit, at 32"wide, 22"deep and 40"high these things don't easily fit anywhere....lol
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Old 06-13-2014, 10:43 PM
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really nice donny. really nice!

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Old 06-13-2014, 11:00 PM
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Its crazy John,
I was like the 3rd guy to build an original Marty sub and a few months later there must be a couple of hundred out their at least. The guy I shipped the 30cuft Marty is starting to put it together. Will post some pics when he's done. You must be pretty proud of all your builds out their John.
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Old 06-13-2014, 11:05 PM
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THAT LOOKS FANTASTIC !!!


Did you use teak quarter round on the edges or is that stained pine?

Last edited by Peterc613; 06-13-2014 at 11:09 PM.
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Old 06-13-2014, 11:20 PM
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Teak is Tits!
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Old 06-13-2014, 11:55 PM
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THAT LOOKS FANTASTIC !!!


Did you use teak quarter round on the edges or is that stained pine?
That is red oak on the corners. Wait until I put three coats of lacquer. That's face cut teak peter. You put that bug in my head of using teak and I'm glad I did. Was 120 for the sheet but worth it.

With my video series you could build your own, really.
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Old 06-14-2014, 04:53 AM
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Thanks,
Teak is pricey , but very classy.
That looks awesome Donny....looking forward to the video!

Kyle
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Old 06-14-2014, 09:14 AM
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Spoiler!


Can't wait to see the video

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Old 06-14-2014, 11:07 AM
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Lightbulb Including a high pass in the model

Quote:
Originally Posted by Peterc613 View Post
Quote:
Originally Posted by LTD02 View Post
after re-reading your post a few times, I suspect that most of your questions are answered by knowing that at subwoofer frequencies, the sound is not directional and "beaming" as you have presented it in your pictures, but extends from the subs more as concentric circles with the sound reflecting off the walls and ceiling as though you inflated a giant balloon at the point of your subwoofer.


there will not be a null in between the subs. the spl with the drivers aimed sideways or forward will vary a bit, but more from things like 1/4 wave reflections off the rear wall for forward mounted drivers. the direction of the port matters very little as the bass wave at 20hz for example is 56.5 feet long, so it is "everywhere" in the room even before it has left the subwoofer.



i would suggest trying to find an enclosure design that keep the port to about 36-40" or so but that can be pushed if these are mostly movie spl machines. the concern is the first port resonance. that can get close to the passband if the ports get too long.
Could someone explain what LDT02 is talking about "the concern is the first port resonance. that can get close to the passband if the ports get too long." I was just trying to get the parameters in the port velocity tab to stay reasonably close to what I saw in WinISD for Marty Cube and Mini Marty. I noticed it said that the port resonance was at about 129 Hz but assumed that this would be above by the preamp's crossover around 90 Hz and not relevant as long as I stayed above the crossover slope.

Also, I am concerned about tight response for these subs to integrate them with my Martin Logans. I didn't think of them as "SPL machines for Movies" as we don't play the electrostats at ear splitting levels. I did want them to be able to produce a tangible punch for LFE special effects even though I have a large room. I was under the impression that you can reproduce deep bass without needing every frequency to be at 125db.

What port size and length would LDT02 recommend for an approx 8 cu ft sub with these 29" x 24" x 32" dimensions?
Looks like you forgot to include the high pass filter in the model. If you dont have the HP included in the model you port speed will look much worse than it really is because you will have to use a high pass filter on the real ported speaker. This sometimes leads to over-dimensioning of the port for no reason and reduced performance because the big port occupies a lot of volume in the box. Also the cone excursion in the model will be off if you dont include the filter.

Random subwoofer model With HP filter to show the effect:








Without filter:




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Last edited by splotten; 06-14-2014 at 12:17 PM.
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Old 06-14-2014, 01:36 PM
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Talking

Quote:
Originally Posted by chalugadp View Post
Quote:
Originally Posted by Peterc613 View Post


THAT LOOKS FANTASTIC !!!


Did you use teak quarter round on the edges or is that stained pine?
That is red oak on the corners. Wait until I put three coats of lacquer. That's face cut teak peter. You put that bug in my head of using teak and I'm glad I did. Was 120 for the sheet but worth it.

With my video series you could build your own, really.



Lumber liquidators has solid teak quarter round for $1.96 a linear foot:

http://www.lumberliquidators.com/ll/...RGTSM/10012111

I sure like the way it looks on the edges. And your supplier's face cut is just as pretty as my guy's quarter cut. Gives it a real finished look. Maybe we should build four of them...
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Old 06-14-2014, 01:50 PM
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Here us with lacquer done

Just need to wait for it to dry
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Old 06-14-2014, 02:04 PM
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Quote:
Originally Posted by splotten View Post
Quote:
Originally Posted by Peterc613 View Post
Quote:
Originally Posted by LTD02 View Post
after re-reading your post a few times, I suspect that most of your questions are answered by knowing that at subwoofer frequencies, the sound is not directional and "beaming" as you have presented it in your pictures, but extends from the subs more as concentric circles with the sound reflecting off the walls and ceiling as though you inflated a giant balloon at the point of your subwoofer.


there will not be a null in between the subs. the spl with the drivers aimed sideways or forward will vary a bit, but more from things like 1/4 wave reflections off the rear wall for forward mounted drivers. the direction of the port matters very little as the bass wave at 20hz for example is 56.5 feet long, so it is "everywhere" in the room even before it has left the subwoofer.



i would suggest trying to find an enclosure design that keep the port to about 36-40" or so but that can be pushed if these are mostly movie spl machines. the concern is the first port resonance. that can get close to the passband if the ports get too long.
Could someone explain what LDT02 is talking about "the concern is the first port resonance. that can get close to the passband if the ports get too long." I was just trying to get the parameters in the port velocity tab to stay reasonably close to what I saw in WinISD for Marty Cube and Mini Marty. I noticed it said that the port resonance was at about 129 Hz but assumed that this would be above by the preamp's crossover around 90 Hz and not relevant as long as I stayed above the crossover slope.

Also, I am concerned about tight response for these subs to integrate them with my Martin Logans. I didn't think of them as "SPL machines for Movies" as we don't play the electrostats at ear splitting levels. I did want them to be able to produce a tangible punch for LFE special effects even though I have a large room. I was under the impression that you can reproduce deep bass without needing every frequency to be at 125db.

What port size and length would LDT02 recommend for an approx 8 cu ft sub with these 29" x 24" x 32" dimensions?
Looks like you forgot to include the high pass filter in the model. If you dont have the HP included in the model you port speed will look much worse than it really is because you will have to use a high pass filter on the real ported speaker. This sometimes leads to over-dimensioning of the port for no reason and reduced performance because the big port occupies a lot of volume in the box. Also the cone excursion in the model will be off if you dont include the filter.

Random subwoofer model With HP filter to show the effect:








Without filter:






Are you saying that I need to include a high pass filter in one of the WinISD tabs to remove any frequencies approaching the X-max of the diver? What cut off point, how many poles for attenuation and what Resonance is optimal to integrate the UXL-18 driver in an 8 cu ft enclosure with 2200 watts ?

Maybe I'm just being dense but I'm still new to subwoofer design and very confused. Mimicking what I see others do on AVS will only get me so far, at some point I need to truly comprehend what we're doing when you model in WinISD.

Can you explain it a little more and post examples of what setting those parameters looks like in WinISD?

Last edited by Peterc613; 06-14-2014 at 02:08 PM.
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Old 06-14-2014, 03:31 PM
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Quote:
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Here us with lacquer done

Just need to wait for it to dry


All hail Chief Chalugadp !



You are now truly my favorite woodworker next to Randy Bader (who we've been collecting for years)

http://www.randybaderwoodworking.com/content/





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Old 06-14-2014, 03:48 PM
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Bader is pretty sweet.

I'm not as good as passing interest but I can beat him at sketchup.
Time to work on the tutorial after england beats Italy
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Old 06-14-2014, 06:06 PM
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That thing screams awesome...

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Old 06-17-2014, 05:34 PM
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Old 06-17-2014, 08:10 PM
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Test
Take the URL and add [img] and [/img] between it.

Your URL is this: http://www.avsforum.com/forum/attach...8&d=1403051630


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Old 06-17-2014, 08:13 PM
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I am not sure I understand what you are showing though ^

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