12" JBL speaker $29 on black friday at Bestbuy - Page 56 - AVS Forum | Home Theater Discussions And Reviews
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post #1651 of 2704 Old 03-05-2019, 03:10 PM
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Originally Posted by aron7awol View Post
Maybe for music, but for HT usage they are much better suited with a LOT more volume. It takes 4 JBLs in 3.6cf each (14.4cf total) to equal a single UM18 Full Marty in ULF. That's with the same 1200W, same 15Hz tune (this holds true with any tune in the teens BTW):
Thanks for the quick replys! So aron7awol, should I be looking at a minimum of 3.6cf per enclosure? -and would (2) 4" ports like the ones on the VBSS, for example, be better for tuning purposes?? If a larger enclosure would give more tuning options and lower bass response, I would prefer to go that route.
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post #1652 of 2704 Old 03-05-2019, 03:15 PM
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Originally Posted by linux247 View Post
Thanks for the quick replys! So aron7awol, should I be looking at a minimum of 3.6cf per enclosure? -and would (2) 4" ports like the ones on the VBSS, for example, be better for tuning purposes?? If a larger enclosure would give more tuning options and lower bass response, I would prefer to go that route.
It depends on your goals, budget, and space. How big can you fit and are willing to build? For example, if size is somewhat of a constraint but budget isn't as much, then UM18 is a better option. If budget is a constraint but size isn't then the JBLs are perfect. In any case, a larger enclosure will definitely be more efficient, give more tuning options, allow for bigger ports which will chuff less, and give you more ULF capability.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #1653 of 2704 Old 03-05-2019, 03:30 PM
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Originally Posted by LastButNotLeast View Post
The second page of the spec sheet would have told you that.

1.75cf, round port 10" x 4"

Michael


That’s specs for a car and is tuned to 38hz......

I’d think he’d want lower, like closer to 20, which means a very different size box and tube.


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post #1654 of 2704 Old 03-05-2019, 03:45 PM
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Originally Posted by aron7awol View Post
It depends on your goals, budget, and space. How big can you fit and are willing to build? For example, if size is somewhat of a constraint but budget isn't as much, then UM18 is a better option. If budget is a constraint but size isn't then the JBLs are perfect. In any case, a larger enclosure will definitely be more efficient, give more tuning options, allow for bigger ports which will chuff less, and give you more ULF capability.
Okay, I have plenty of space and would like to use the JBL's since I already have them. I could build any size enclosure really, just looking for recommendations from folks who know more about this than I do. I was thinking about the possibility of using them as end tables which would work out to be roughly 4.0cf internal volume per box. Otherwise I could build bigger boxes that are front firing and place them on both sides of the entertainment center instead.
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post #1655 of 2704 Old 03-05-2019, 03:50 PM
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Originally Posted by linux247 View Post
Okay, I have plenty of space and would like to use the JBL's since I already have them. I could build any size enclosure really, just looking for recommendations from folks who know more about this than I do. I was thinking about the possibility of using them as end tables which would work out to be roughly 4.0cf internal volume per box. Otherwise I could build bigger boxes that are front firing and place them on both sides of the entertainment center instead.
Please note, I was not referring to 3.6cf per enclosure, but 3.6cf per driver in a single enclosure of 14.4cf (this is what allows tuning so low). If you can only build 4cf enclosures, that changes everything. If you figure out what size you can build, I'll give you some options.

Edit to add: I guess I shouldn't say it changes everything; you can certainly build 8 enclosures at 4cf each and we can tune them the same with smaller ports and you'll end up with the same output as 2 big enclosures of 16cf with 4 drivers each It's just a lot of boxes to build and a lot of wiring to end up in a place that 2 boxes can easily get you, and at the end of the day you've taken up the same amount of space. You can also do some combination of that and also big enclosures. If you can make a good game plan on placement options, we can tune them all the same and make integration simple. How many JBLs do you have?

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4

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post #1656 of 2704 Old 03-05-2019, 06:27 PM
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I'm giving a single 4 cu ft net enclosure, tuned to 22hz a try. It's very wide (behind my couch so 76.5" wide) which coincidentally will allow me to build the two 4"wide x 30" long ports it calls for. Here is the magnitude graph and spl, with a single driver and an inuke 1000dsp. All this being said, I don't have it built yet, so can't tell you how it sounds...

I know it won't compare in overall output to a wall of these things, but thankfully that's not what I'm going for in my little <1500 cubic ft room.
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post #1657 of 2704 Old 03-05-2019, 11:27 PM
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Quote:
Originally Posted by CheapSpeakerGuy View Post
I'm giving a single 4 cu ft net enclosure, tuned to 22hz a try. It's very wide (behind my couch so 76.5" wide) which coincidentally will allow me to build the two 4"wide x 30" long ports it calls for. Here is the magnitude graph and spl, with a single driver and an inuke 1000dsp. All this being said, I don't have it built yet, so can't tell you how it sounds...

I know it won't compare in overall output to a wall of these things, but thankfully that's not what I'm going for in my little <1500 cubic ft room.
Looks like you did a great job optimizing the design, with plenty of output down low.
You must know your way around WinISD. A great skill for anyone interested in DIY subwoofers.
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post #1658 of 2704 Old 03-06-2019, 05:32 AM
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Quote:
Originally Posted by CheapSpeakerGuy View Post
I'm giving a single 4 cu ft net enclosure, tuned to 22hz a try. It's very wide (behind my couch so 76.5" wide) which coincidentally will allow me to build the two 4"wide x 30" long ports it calls for. Here is the magnitude graph and spl, with a single driver and an inuke 1000dsp. All this being said, I don't have it built yet, so can't tell you how it sounds...

I know it won't compare in overall output to a wall of these things, but thankfully that's not what I'm going for in my little <1500 cubic ft room.

An enclosure with a dimension that long will have a cancellation notch and a peak in the response. Install a polyfill pillow or two near the center of the end to end dimension to kill it.



If left untreated, the enclosure will ring for many cycles after the initial signal, measurements I made had very little attenuation out to 300 msec.
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Ask your doctor if DIY is right for you. Side effects of DIY may include anxiety, elevated blood pressure, lightheadedness, rapid heartbeat, skeletal muscle flaccidity, euphoria, psychological dependence, insomnia, confusion, blurred vision, impulsivity, uncontrolled or repeated movements.
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post #1659 of 2704 Old 03-06-2019, 07:49 AM
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Quote:
Originally Posted by CheapSpeakerGuy View Post
I'm giving a single 4 cu ft net enclosure, tuned to 22hz a try. It's very wide (behind my couch so 76.5" wide) which coincidentally will allow me to build the two 4"wide x 30" long ports it calls for. Here is the magnitude graph and spl, with a single driver and an inuke 1000dsp. All this being said, I don't have it built yet, so can't tell you how it sounds...

I know it won't compare in overall output to a wall of these things, but thankfully that's not what I'm going for in my little <1500 cubic ft room.
I see there is a high pass at 25 HZ an PEQ @ 20 HZ and the excursion is getting a bit high above and below tune. It looks like you will need to lower the watts to keep the driver safe with that high pass and PEQ boost. I'm guessing around 250 - 300 watts. You also have the option of lowering your high pass since your port tune is 22 hz.

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post #1660 of 2704 Old 03-06-2019, 09:36 AM
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Quote:
Originally Posted by CheapSpeakerGuy View Post
I'm giving a single 4 cu ft net enclosure, tuned to 22hz a try. It's very wide (behind my couch so 76.5" wide) which coincidentally will allow me to build the two 4"wide x 30" long ports it calls for. Here is the magnitude graph and spl, with a single driver and an inuke 1000dsp. All this being said, I don't have it built yet, so can't tell you how it sounds...

I know it won't compare in overall output to a wall of these things, but thankfully that's not what I'm going for in my little <1500 cubic ft room.
Your Filters need some tweaking. If your goal is a 22hz tuned port, then your highpass should be at or below that frequency. So you will want to adjust your highpass to 22hz or even 21, I wouldn't go lower.

Additionally because of the highpass adding a PEQ filter at 20hz isnt something I'd do. Your adding boost to an area you told the amp to reduce, so its just not a good idea, even if it makes it look a bit better on paper.

Where are you terminating the port? Out the sides? If you can, maybe think about adding a bend and having it port out the front of the box, so that its hitting your couch. Since you need two ports, perhaps put one exiting per section to spread out the force coming from the port.

Might be one more way to enhance your tactile feel that costs you absolutely nothing (except maybe some extra wood to prop up the ports).

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post #1661 of 2704 Old 03-06-2019, 10:48 AM
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Quote:
Originally Posted by DavidK442 View Post
Looks like you did a great job optimizing the design, with plenty of output down low.
You must know your way around WinISD. A great skill for anyone interested in DIY subwoofers.

Actually, I know enough to be dangerous. Honing in on what was better and what not was with a lot of input from @EndersShadow and reporting from @Zarkoff500 that a box with this volume, wattage and tuning frequency sounded pretty good. I may have gotten a little too fancy (or not fancy enough?) with the high-pass filters and what not. I'll heed the warnings and put the filters where suggested. I assume to limit the wattage I do that in the "Peak" section of the inuke?


Regarding the port............


I did plan to run them lengthwise, but was thinking of staggering them, so one was closer to front and one was closer to rear (and possibly higher). If that would still lead to weird dynamics I don't mind putting in poly fill if that will help deaden it.


Regarding the port firing, I guess I could put a 90 in and send it out the front, but when the seats are upright they will be very close to the ports and I'd be afraid at times they could even block them. The woofer will have a grill on it to allow at least the full excursion, but the ports, if front firing might be right against the cloth if my kids wrestle and push the couch back inadvertently.


Thoughts on the ports being offset and or side firing?
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post #1662 of 2704 Old 03-06-2019, 03:03 PM
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No thoughts on that personally...

Will redo the WinISD model for you and try to post screenshots tonight.

If you PM me your email I can also send you the file once I’m done w it.


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post #1663 of 2704 Old 03-06-2019, 03:36 PM
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Originally Posted by aron7awol View Post
Please note, I was not referring to 3.6cf per enclosure, but 3.6cf per driver in a single enclosure of 14.4cf (this is what allows tuning so low). If you can only build 4cf enclosures, that changes everything. If you figure out what size you can build, I'll give you some options.

Edit to add: I guess I shouldn't say it changes everything; you can certainly build 8 enclosures at 4cf each and we can tune them the same with smaller ports and you'll end up with the same output as 2 big enclosures of 16cf with 4 drivers each It's just a lot of boxes to build and a lot of wiring to end up in a place that 2 boxes can easily get you, and at the end of the day you've taken up the same amount of space. You can also do some combination of that and also big enclosures. If you can make a good game plan on placement options, we can tune them all the same and make integration simple. How many JBLs do you have?
@aron7awol thanks for the clarification. I proposed the 4.0cf sub idea that "looks" like an end table to my wife but she prefers a narrower, less obtrusive enclosure design @ ~3.0cf. I wasn't thinking she'd be picky about it so I'm hoping to change her mind if it makes enough of a difference . Also if it's worth doing, I'm thinking I would like to build two more later for the front of the room for a total of four. So at this point would you mind running the numbers at both 3.0cf and 4.0cf (w/one or two ports - whichever is better?) Gracias
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post #1664 of 2704 Old 03-06-2019, 04:25 PM
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@aron7awol thanks for the clarification. I proposed the 4.0cf sub idea that "looks" like an end table to my wife but she prefers a narrower, less obtrusive enclosure design @ ~3.0cf. I wasn't thinking she'd be picky about it so I'm hoping to change her mind if it makes enough of a difference . Also if it's worth doing, I'm thinking I would like to build two more later for the front of the room for a total of four. So at this point would you mind running the numbers at both 3.0cf and 4.0cf (w/one or two ports - whichever is better?) Gracias
3cf each works too. A total of four will pretty much equal the output of a single Marty. Do you foresee yourself being able to add any more subs to the room down the road in addition to the 4? The answer to that will determine what tuning point is probably best for the application. Will any of the 4 locations you have in mind get boundary reinforcement from a nearby wall or corner?

I'll show you the difference between 3cf each and 4cf each shortly...

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #1665 of 2704 Old 03-06-2019, 04:40 PM
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Originally Posted by aron7awol View Post
3cf each works too. A total of four will pretty much equal the output of a single Marty. Do you foresee yourself being able to add any more subs to the room down the road in addition to the 4? The answer to that will determine what tuning point is probably best for the application. Will any of the 4 locations you have in mind get boundary reinforcement from a nearby wall or corner?

I'll show you the difference between 3cf each and 4cf each shortly...
Four would probably be the limit of what I'd be able to get away with. All four will have a wall behind them - the rear subs next to the couch will be down firing and the front ones could either be down or front. If I start with two rear end table subs, when I add the additional ones can the ports be tuned differently to accommodate - (if that matters?)
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post #1666 of 2704 Old 03-06-2019, 04:56 PM
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Four would probably be the limit of what I'd be able to get away with. All four will have a wall behind them - the rear subs next to the couch will be down firing and the front ones could either be down or front. If I start with two rear end table subs, when I add the additional ones can the ports be tuned differently to accommodate - (if that matters?)
We could certainly set them up with multiple ports each so that you can tune them lower once you have four, but you're really going to need 4 of these, so I think we should at least gameplan around that, while trying to set you up with a decent experience with 2 in the meantime.

Here's a comparison of 4 @ 4cf each vs 4 @ 3cf each, both cases with 300W each and tuned @ 17Hz. Basically the bigger boxes end up with a ~2dB advantage between 15-20Hz while maintaining the same port velocity.


Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4

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post #1667 of 2704 Old 03-06-2019, 05:24 PM
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Originally Posted by aron7awol View Post
We could certainly set them up with multiple ports each so that you can tune them lower once you have four, but you're really going to need 4 of these, so I think we should at least gameplan around that, while trying to set you up with a decent experience with 2 in the meantime.

Here's a comparison of 4 @ 4cf each vs 4 @ 3cf each, both cases with 300W each and tuned @ 17Hz. Basically the bigger boxes end up with a ~2dB advantage between 15-22Hz while maintaining the same port velocity.
@aron7awol Thanks for this. Out of curiosity, how do you determine at which low freq. to tune at - is it based on some characteristic(s) from the spec sheet? Also does that ~2dB advantage between 15-22Hz really make much of an appreciable difference?
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post #1668 of 2704 Old 03-06-2019, 05:36 PM
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@aron7awol Thanks for this. Out of curiosity, how do you determine at which low freq. to tune at - is it based on some characteristic(s) from the spec sheet? Also does that ~2dB advantage between 15-22Hz really make much of an appreciable difference?
I would decide tuning based on the total output of the system, the size of the room, and what your normal listening level is, but it would be somewhere in the mid to high teens.

It's tough to say how much of an impact that 2dB will make in your particular case. On one hand, it's just 2dB, but on the other hand that headroom could be exactly what you need to be flat to 15Hz in your room at your listening level. In any case, it's not going to be an enormous difference, but if these boxes are the only subs you can put in this room, you may want to give yourself that extra certainty that they will give you what you want out of them. Along the same line, if you can only put these 4 subs in this room, you may want to strongly consider going with the 4cf option and upgrading the drivers to UM18s or stuffing 2 JBLs in each box. Of course, this is only if budget allows.

Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Fusion-8 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #1669 of 2704 Old 03-09-2019, 09:14 PM
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Finished up the computer subwoofer. Four of the JBL's heavily stuffed in about 1.3 cu ft each. No measurements yet, literally just hooked it up and used whatever eq the previous ported 10's used. Had to saw away a lot of the bottom of the desk to get her to fit, haha!


I'll post some before-eq and after eq measurements. Currently sounds questionable but... huge impact.
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post #1670 of 2704 Old 03-09-2019, 10:13 PM
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Why did you "heavily stuff" the boxes?
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post #1671 of 2704 Old 03-09-2019, 10:29 PM
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I built a quick sealed box out of scrap to mostly test out putting a cabinet together before my main build of a the ported 4 cu ft. single couch sub.

I am running an iNuke 1000DSP and clearly I have a setting wrong, either being in the wrong mode, not wiring right (I have it wired in Bridge 1+ and 2+) or most likely something wrong in the settings because I am barely getting 1 light orange light and I have the gain set to max and subwoofer trim at max DB. Do I need both inputs plugged in? I am currently using 1 RCA to TS adapter. Speak-on connected to Channel A.

Observations so far, about the same output or less than my cheapo 10", but again I know I have something wrong.

Second observation, the fan in the iNuke is as described, totally unacceptable if close to listening position.
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post #1672 of 2704 Old 03-09-2019, 10:43 PM
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Why did you "heavily stuff" the boxes?
Are you serious? Can't tell.

Reasons: Lower Fs, smooth impedance peak, reduce internal reflections, lower Q.

In general the smaller the box the more stuffing/cuft you'd put in. These are pretty small so I put near 1.8 lbs per cu ft in there, which is close to optimal in that size box via my testing with DATs.

Try it sometime if you have access to something like DATS. You'll see Fs start to drop and the impedance peak calm down.

Real world, I dropped about 5hz before messing with eq. This is primarily through losing some upper bass efficiency -the old thought that stuffing "makes the sub think it's in a bigger box" isn't quite true, but unless you're just going for SPL it's still a good idea and can definitely reduce audibility of internal reflections (majoring in the minors).

See pics, for zero stuffing vs. about 1.4 lbs/cuft of stuffing. I took another sweep at 1.8 and liked it better but of course didn't save that one.

Chris
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post #1673 of 2704 Old 03-10-2019, 07:47 AM
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Originally Posted by Chris Popovich View Post
Are you serious? Can't tell.
Yes, very serious (otherwise, some snarky emoji follows).
And I appreciate the thorough explanation. So now, when I get my boxes, they, too, will be "heavily stuffed."
Thank you.
Seriously.

Michael
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post #1674 of 2704 Old 03-10-2019, 08:11 AM
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Quote:
Originally Posted by Chris Popovich View Post
Are you serious? Can't tell.

Reasons: Lower Fs, smooth impedance peak, reduce internal reflections, lower Q.

In general the smaller the box the more stuffing/cuft you'd put in. These are pretty small so I put near 1.8 lbs per cu ft in there, which is close to optimal in that size box via my testing with DATs.

Try it sometime if you have access to something like DATS. You'll see Fs start to drop and the impedance peak calm down.

Real world, I dropped about 5hz before messing with eq. This is primarily through losing some upper bass efficiency -the old thought that stuffing "makes the sub think it's in a bigger box" isn't quite true, but unless you're just going for SPL it's still a good idea and can definitely reduce audibility of internal reflections (majoring in the minors).

See pics, for zero stuffing vs. about 1.4 lbs/cuft of stuffing. I took another sweep at 1.8 and liked it better but of course didn't save that one.

Chris
Any issues with stuffing up against the driver?
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post #1675 of 2704 Old 03-10-2019, 08:59 AM
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Quote:
Originally Posted by Chris Popovich View Post
Are you serious? Can't tell.

Reasons: Lower Fs, smooth impedance peak, reduce internal reflections, lower Q.

In general the smaller the box the more stuffing/cuft you'd put in. These are pretty small so I put near 1.8 lbs per cu ft in there, which is close to optimal in that size box via my testing with DATs.

Try it sometime if you have access to something like DATS. You'll see Fs start to drop and the impedance peak calm down.

Real world, I dropped about 5hz before messing with eq. This is primarily through losing some upper bass efficiency -the old thought that stuffing "makes the sub think it's in a bigger box" isn't quite true, but unless you're just going for SPL it's still a good idea and can definitely reduce audibility of internal reflections (majoring in the minors).

See pics, for zero stuffing vs. about 1.4 lbs/cuft of stuffing. I took another sweep at 1.8 and liked it better but of course didn't save that one.

Chris
Hey Chris, thanks for doing the homework for us! I stopped stuffing my 8 JBLs at probably just under a pound each. I didn't compress it much and the stuff was getting close to where the magnet and back of the driver would be so I stopped. I didn't have any hard evidence that continueing to stuff them would be of any benefit. Until your post. Thanks.
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post #1676 of 2704 Old 03-10-2019, 09:04 AM
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It's a trade off. You do lose some spl when using stuffing. But you gain some stuff too.

- 6 BA CR6 array center channel, QSC AD-S82 L/R, 4 jbl 8330a surr , 8 jbl 12" subs w/Inuke 6000. JVC rs420, Denon x4000, Sony x800 -
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But you gain some stuff too.
Ouch.
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post #1678 of 2704 Old 03-10-2019, 10:00 AM
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Quote:
Originally Posted by LastButNotLeast View Post
Yes, very serious (otherwise, some snarky emoji follows).
And I appreciate the thorough explanation. So now, when I get my boxes, they, too, will be "heavily stuffed."
Thank you.
Seriously.

Michael

Remember there is an optimum stuffing amount, and it changes based on box size.

Quote:
Originally Posted by RoboAVS View Post
Any issues with stuffing up against the driver?
None for me. In the past I used a piece of batting on the top to sort of control the loose fiber fill. Did not do that this time.

Quote:
Originally Posted by jcmccorm View Post
Hey Chris, thanks for doing the homework for us! I stopped stuffing my 8 JBLs at probably just under a pound each. I didn't compress it much and the stuff was getting close to where the magnet and back of the driver would be so I stopped. I didn't have any hard evidence that continueing to stuff them would be of any benefit. Until your post. Thanks.
Glad to help. I think it's impossible to tell optimal without DATS or the equiv. but these small (1.3-1.5 cuft approx) boxes like about 1.75 lbs/cuft, which makes for something in the 2-2.5ish lbs of stuffing per enclosure

Quote:
Originally Posted by trilkb View Post
It's a trade off. You do lose some spl when using stuffing. But you gain some stuff too.
For sure. There is an extreme low bass gain of a couple db's (usually negligible), the low bass is not impacted much at all, and the upper bass efficiency gets pulled down a couple db's, which on a 60hz peaky design like this is fine, plus reduction of internal reflections, which is always good from a sq perspective.

Chris
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post #1679 of 2704 Old 03-10-2019, 10:01 AM
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12&quot; JBL speaker $29 on black friday at Bestbuy

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Originally Posted by LastButNotLeast View Post
Ouch.


Databass.com has an article on this. Don’t feel like linking it it (some did already in this thread).

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Last edited by EndersShadow; 03-10-2019 at 10:09 AM.
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post #1680 of 2704 Old 03-10-2019, 10:15 AM
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Was referring to the pun on "stuff."
Maybe the hour I lost last night affected my sense of humor.
Michael
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