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View Full Version : JBL L5 Sub crossover advice



Chris Brown
03-07-2016, 02:15 PM
The L5 speakers in my setup stand out as having one of the most pleasing sounds of any speaker I own, but at the same time they just can't handle the bass compared to my other JBLs (all of which have 12" woofers). That 708g-1 is a real trooper and I don't fault it at all. It's amazing how much bass it actually puts out given it's size, but unfortunately above a certain point I get a fluttering sound that is either port noise or the woofer simply going beyond it's abilities. I am thinking about moving this pair over to the HT system, which has a decent subwoofer. Of course trial and error is always an option but I wanted to see if any of you were in a similar situation and have any recommendations as to what is an appropriate LF/sub crossover for the L5s. If I crossed them over at 60hz for example, would that still be asking too much of the 708g-1 in all of your opinions?

I also find it slightly odd that the 706G-1 barely moves at all while the 708G-1 is practically jumping out of the cabinet, despite the fact that JBL lists both the 708G-1 and the 706G-1 as LF Transducers in the manual (http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=49126&d=1293591230), as opposed to the 706G-1 being listed as a "mid-bass Transducer" like you might expect for a 4-way

BMWCCA
03-07-2016, 06:43 PM
It's amazing how much bass it actually puts out given it's size, but unfortunately above a certain point I get a fluttering sound that is either port noise or the woofer simply going beyond it's abilities.
Just a thought but did you check the surrounds for any loose or split material? Is everything secured properly to the cone? :dont-know:

jblnut
03-08-2016, 08:37 AM
Yeah you get to a point with the L5 where - if you like your bass loud - the L7 starts to make sense. I started a friend off on this path many years ago and he finally did the upgrade to L7 because he likes his music very loud on occasion. I think if you crossed the L5 over high enough, you might get away with using a sub and being able to avoid over excursion on that 8" driver. But the question is - will you like the results and will it be crossed over too high (meaning localization of the sub becomes a problem)? Only you can answer that as you dial it in for your room and your music/movies.

jblnut

Chris Brown
03-08-2016, 09:33 AM
Just a thought but did you check the surrounds for any loose or split material? Is everything secured properly to the cone?

They are in fantastic condition thankfully. I do believe it's simply hitting it's limits. The amount of cone movement on the 708G-1 is almost scary compared to what I've come to expect from my 12" woofers in order to produce the same bass at the same listening levels - and even with the 12s I have caused woofer over-excursion in the past (mostly the 128H woofers in my L150s). So I think I'm just asking too much of them at times.



Yeah you get to a point with the L5 where - if you like your bass loud - the L7 starts to make sense. I started a friend off on this path many years ago and he finally did the upgrade to L7 because he likes his music very loud on occasion. I think if you crossed the L5 over high enough, you might get away with using a sub and being able to avoid over excursion on that 8" driver. But the question is - will you like the results and will it be crossed over too high (meaning localization of the sub becomes a problem)? Only you can answer that as you dial it in for your room and your music/movies.

I would snap up a pair of L7s quickly if I had the chance, though I don't think I would really be able to accommodate it's placement needs.

Ultimately I love the sound from my L5 speakers a LOT. I will always love the laid-back sound from my L150s along with it's soft passive-radiator bass but I think that with a good sub the L5s could easily become my favorite speakers. The sub could give me the bass I want, and also make it so I can enjoy my music instead of worrying about breaking my L5s :)

gasfan
03-08-2016, 09:45 AM
I used my L5s with twin Velodyne DPS12s crossed as low as possible, at 40hz. I also don't over do the bass unless you consider flat response to 26hz overdone. I suppose technically it is. However, they don't drown out the L5s by any means and I play my music very loud very often. I've never seen what would appear to be overexcursion on the L5s. Nor have I ever heard them sound overdriven in any sense of the word. I'm talking about peaks of 104db at 12 ft. away. So that's well over their rated output at 1 meter.
There must be something wrong with those drivers/speakers.

I should point out that I play the L5s dead flat, no eq.

Chris Brown
03-08-2016, 11:01 AM
There must be something wrong with those drivers/speakers.

I should point out that I play the L5s dead flat, no eq.

I do tend to use EQ, so that is probably a factor.

I have made a short video to attempt to show you all what I am experiencing with the 708G-1 drivers. Obviously the video has inherent limitations, and the sound in the video is very garbled because apparently the Microphone on my webcam does not like Bass, but it should get the idea across. The video gets serious at about 20 seconds in. SPL meter in the background is measuring using dBC. It may seem like I am pushing them very hard but this level of bass is a cake-walk with my other JBLs.

I have the video on Youtube, or alternatively you can download the source video itself directly from my web-server:

Youtube: https://www.youtube.com/watch?v=1ZR12g1WJgw
Source Video: http://gotnorice.com/708G_BASS.wmv

grumpy
03-08-2016, 01:42 PM
easy to over do bass eq on a ported system.

looks like they're being driven below resonance (basically, the driver is free to flop around when
driven that low).

any reasonably normal 8" driver (not a dedicated high power sub) will run out of gas at some point (not real low and loud at the same time).

Unless the spiders have been destroyed from overexcursion, just cut the EQ below 40Hz and see how it goes.

Add subs to taste.

gasfan
03-08-2016, 02:53 PM
Imo, the L5s definitely need a sub woofer. Heck, I use them with my Kappa 9s. It's the only way to get at the bottom and keep it clean and tight.

Robh3606
03-08-2016, 03:07 PM
I cross mine over at 80 hz Works just fine

Rob:)

Chris Brown
03-08-2016, 03:22 PM
any reasonably normal 8" driver (not a dedicated high power sub) will run out of gas at some point (not real low and loud at the same time).

Imo, the L5s definitely need a sub woofer.

Yeah I guess I will just have to try it, see how it goes. HT sub will have to do for now but I've long wanted to get a nice musical sub (or several), probably sealed, even for my larger JBLs.

For fun I made a similar video, with the same song, same EQ settings, etc with my L150s instead. I actually had them a bit louder, about 3-5 dBC louder according to the meter, and even then those 128H woofers were not even close to their max potential.

Youtube: https://youtu.be/_zrm2QbCfU4
Source Video: http://gotnorice.com/128H_BASS.wmv
(http://gotnorice.com/128H_BASS.wmv)


I cross mine over at 80 hz Works just fine

That is THX spec right?

gasfan
03-08-2016, 04:11 PM
The DPS12s are "HT" subs. I really don't get the distinction. Subs are not about 'speed' or definition, but extension. The definition is all in the mains. How does your HT sub sound all by itself? Doesn't "HT" require bass definition?

Chris Brown
03-08-2016, 06:08 PM
I was really just referring to it as the subwoofer that is in my HT, rather than implying any particular type of sub. Anything negative I may have implied is just because my HT has never been as high of a priority as my music system, so it's comprised of cheaper components.

gasfan
03-09-2016, 01:06 PM
I mention it because I've seen lots of comments disparaging so called 'HT' subs for 2ch audio use. The only comparative factors I can see are driver size, extension and power rating. Interestingly enough, I called Velodyne regarding the volume control on the DPS12 and the tech on the line seemed a bit puzzled that I was using them strictly for 2ch. stereo, almost ridiculing. However, they come with pre programmed presets for various music genres, ie: R&B, Rock, Jazz, Classical, and separate presets for Movies and games, permanently printed on the touch pad. Weird. They come with 400w built in amps and work very well.