[tomlinmgt]

I have a pair of modified JBL 4648 bass bins I'm using for subs (ports extended 7.5" to lower the port tuning).  With corner loading, they're measuring -3db @ 23 Hz and can deliver some serious distortion free SPL with around 300 wpc.  I've been able to integrate them beautifully with some other speakers...Klipsch Epic CF-4, Altec 19, x-Statiks, Tekton Double Impact, Aerial Acoustics 10t mkII, ADS 1290/2...but have struggled with a few others including the LS6's, Vandersteen 3a Signature and Infinity QLS-1 (also a line source).

The 4648's being passive, I used an Ashly active crossover to dial them in and it worked beautifully for the speaker models I mentioned resulting in all bass content from 20-250Hz being super tight and articulate. But with the three models I've had trouble getting integrated, I'm hearing what I can best describe as some overhang or ringing around 90-125 Hz...so that the bass energy in that region seems to linger with poor recovery/settling time or articulation.

I'm using a DSPeaker Anti-Mode 8033 in the sub circuit to remove any modal activity/peaks the subs are exciting, so there is no uncontrollable "boom" coming from the subs . 

I've tried the LS6's anywhere from 3'-7.5' out from the front wall and 5' out seems to be the sweet spot in terms of achieving balanced, articulate bass from the mains.

What has proven to help the issue, and by quite a lot, is swapping out the Ashly unit for a MiniDSP 2X4 HD and creating a super steep slope at the cutoff frequency which I prefer to set around 80 Hz (for that killer chest thump from the bass drum).  I think the Ashly unit is fixed at -24db LR, but the steeper I go beyond that, the better it gets (max is -48 db...haven't yet decided if I prefer Linkwitz or Butterworth). 

But as much as it's improved with the MiniDSP, I still hear a little bit of a delay in the problematic spectral region with some tracks...tracks that have a really punchy, articulate bass drum, in particular.  So now I'm wondering if I may be up against a timing issue rather than just a frequency issue. The subs sit about four feet further away from the listening spot than the mains but again, other speakers that have a similar main/sub/listening spot distance relationship haven't had an issue.  Could it be the unique dispersion pattern of LF energy from the line source design that is the problem?

The room is 19x26 with a vaulted ceiling to 14', is a dedicated space with EXTENSIVE acoustic treatments including a 48 sqft, 6" thick limp bag low frequency absorber built into the back wall. The entire ceiling is a mid/upper bass trap that operates in the 125-400Hz re
gion. I don't think room acoustics are the problem since I've not had this issue with several other speakers. 

Thoughts?

- Michael

[Danny Richie]

You may actually be fighting several issues here.

First of all, I cringe to think that the signal to the main speakers is passing through a Mini DSP. That is a bottleneck in all areas. I can see using it as an EQ for a sub, but there is no way I would want the signal to my main speakers passing through that.

Secondly, the measurements that I have of the LS-6's in my old listening room showed a response that was not only flat to 20Hz, but added a 3db peak at 20Hz. Bass response from a group of small 6.5" woofers with a long throw design like this is kind of hard to match with a sub. This would be especially true with a non-servo controlled subs that used large woofers with high moving mass. You may have much better results letting the LS-6's play full range and then moving the subs to the back of the room and letting them play up to about 25Hz and run them out of phase from the main speakers. These will really minimize room interaction and room boom.

There is also a bass management system built into the LS-6's that can be accessed through the back panel. It is basically an overbuilt LCR circuit designed to reduce output in an area typical of room gains. It is centered at 70Hz and is very adjustable. The AV123 version had jumpers on a circuit that allowed you to quickly and easily make adjustments.

I also noticed something about your room. It looks well treated with diffusers and some absorbing panels. However, you may need some rather thick tube traps or bass traps for the corners of the room.

[Hafgrim]

You might be hearing a resonance from the sub box or the port.

The mini dsp does add a 3-5 ms of delay by it self.

[HAL]

Have you time delayed the main speakers the offset distance from the subs to the mains? 

You can measure it with a tape measure and adjust the mains depending on the time of travel at 1130ft/Sec for the time delay needed.

If you are using the miniDSP to work with the mains and subs the processing delay will be the same for both speakers, so only the distance offset needs to be corrected.

The dspNexus 2/8 system I use has better sound quality to me than the miniDSP and others like a DCX2496 and DEQX.  I have replaced a DEQX 2.6p and a friend with an DEQX Express II with the dspNexus with better sound quality.

Helping a friend with LS-9's now with the dspNexus 2/8 to integrate his two 3x12 OB servo subs once they are completed.  He also removed the passive XO and went full active with the system.

Hope this helps.

[tomlinmgt]

Thanks Danny.  To be clear, the MiniDSP is on the sub circuit only. The signal path is source>pre where it then splits into separate paths for the subs and mains. The single path for the main speakers after the preamp is straight to the main amp then speakers.

I can't move the subs to the rear since I have my drums set up in one of the back corners...and the drums aren't going anywhere.  Besides that, the first place I tried the subs when I first introduced them to the room was in the rear corners. In those locations, they sounded a little sloppy and didn't measure so great.  I had success in my prior listening space with subs on the rear wall, but in this room that configuration just doesn't seem to pan out.  Relocating them to the front corners was a significant improvement sonically and the measurements looked a lot better, as well.  And there's still the fact that I've had several other speakers that, when combined with the subs, sound absolutely fantastic. So I'm not so sure the room is the issue unless the line source is interacting differently with the room, necessitating a different treatment scenario.  I have two 8' tall superchunk corner traps from my prior listening space that I'm not using in the new space. I suppose I can get those out and give them a try. But make no mistake, the room does not have any serious modal activity occurring. The interior walls are fabric over insulation with two layers of sheathing making up the exterior wall.  There is zero masonry in the wall construction...so a good bit of LF energy is able to pass right through the walls as opposed to if there were brick, stone cinder block or earth. The limp bag LF absorber in the rear of the room is the same design used in commercial bass trapping installations and has proven to be very effective in recording studio environments...moreso than the superchunks or tube traps.

As far as making adjustments to the crossover, I'm already getting a good bit of excursion from the mid bass drivers at high SPL when playing bass heavy content.  I'm a little reluctant to do anything that would boost the low end further for fear that I'm introducing distortion and stress on the out of production drivers...which is another reason I want to use the subs. The subs allow me to get strong, tactile bass at moderate listening levels.  To get that same sensation of bass impact from the LS6's alone, I have to bring the volume up quite a bit which is harder on my ears and, potentially, the unobtanium mid bass drivers.

[tomlinmgt]

Have you time delayed the main speakers the offset distance from the subs to the mains? 

You can measure it with a tape measure and adjust the mains depending on the time of travel at 1130ft/Sec for the time delay needed.

If you are using the miniDSP to work with the mains and subs the processing delay will be the same for both speakers, so only the distance offset needs to be corrected.

The dspNexus 2/8 system I use has better sound quality to me than the miniDSP and others like a DCX2496 and DEQX.  I have replaced a DEQX 2.6p and a friend with an DEQX Express II with the dspNexus with better sound quality.

Helping a friend with LS-9's now with the dspNexus 2/8 to integrate his two 3x12 OB servo subs once they are completed.  He also removed the passive XO and went full active with the system.

Hope this helps.

I have not tried to delay the mains because I'm reluctant to run the main circuit through the DSP for fear of signal quality degradation. But for sure, I wish I had a way to delay the mains without compromising fidelity.

[tomlinmgt]

You might be hearing a resonance from the sub box or the port.

The mini dsp does add a 3-5 ms of delay by it self.

If it were port or cabinet noise, would I not hear it with all the other speakers, too?

Can I remove the default delay?

[Tyson]

Easiest thing to do is physically move the subs so they are next to the speakers and see if that solves the problem.

[tomlinmgt]

Easiest thing to do is physically move the subs so they are next to the speakers and see if that solves the problem.

Yes, I figure that's likely my next, easiest move. Only downside I can think of is that I lose all boundary loading and maybe create modal issues with the different placement.

[Early B.]

I'm guessing the subs can't keep up with the LS6's, no matter what you do. A big clue is the subs were also difficult to integrate with another line-source speaker. In other words, you may be sub-optimal (I always wanted to say that...).

[Tyson]

You could also try running the LS6's full range with the subs off for a while and see if you even need the subs at all, as Early B. suggests.

[tomlinmgt]

You could also try running the LS6's full range with the subs off for a while and see if you even need the subs at all, as Early B. suggests.

I've been listening to them without the subs for nearly a few months now and have a very good idea what they can and can't do on their own. With the subs, there is no high pass for the mains. They're running full range.

[tomlinmgt]

I'm guessing the subs can't keep up with the LS6's, no matter what you do. A big clue is the subs were also difficult to integrate with another line-source speaker. In other words, you may be sub-optimal (I always wanted to say that...).

The QLS-1's have line source driver arrays for the mids and highs only. The LF driver and "mid bass coupler" driver are both singular units...so there is a difference between how the LS6's load the room with LF energy compared to the big vintage Infinities.

[Danny Richie]

Thanks Danny.  To be clear, the MiniDSP is on the sub circuit only. The signal path is source>pre where it then splits into separate paths for the subs and mains. The single path for the main speakers after the preamp is straight to the main amp then speakers.

I can't move the subs to the rear since I have my drums set up in one of the back corners...and the drums aren't going anywhere.  Besides that, the first place I tried the subs when I first introduced them to the room was in the rear corners. In those locations, they sounded a little sloppy and didn't measure so great.  I had success in my prior listening space with subs on the rear wall, but in this room that configuration just doesn't seem to pan out.  Relocating them to the front corners was a significant improvement sonically and the measurements looked a lot better, as well.  And there's still the fact that I've had several other speakers that, when combined with the subs, sound absolutely fantastic. So I'm not so sure the room is the issue unless the line source is interacting differently with the room, necessitating a different treatment scenario.  I have two 8' tall superchunk corner traps from my prior listening space that I'm not using in the new space. I suppose I can get those out and give them a try. But make no mistake, the room does not have any serious modal activity occurring. The interior walls are fabric over insulation with two layers of sheathing making up the exterior wall.  There is zero masonry in the wall construction...so a good bit of LF energy is able to pass right through the walls as opposed to if there were brick, stone cinder block or earth. The limp bag LF absorber in the rear of the room is the same design used in commercial bass trapping installations and has proven to be very effective in recording studio environments...moreso than the superchunks or tube traps.

As far as making adjustments to the crossover, I'm already getting a good bit of excursion from the mid bass drivers at high SPL when playing bass heavy content.  I'm a little reluctant to do anything that would boost the low end further for fear that I'm introducing distortion and stress on the out of production drivers...which is another reason I want to use the subs. The subs allow me to get strong, tactile bass at moderate listening levels.  To get that same sensation of bass impact from the LS6's alone, I have to bring the volume up quite a bit which is harder on my ears and, potentially, the unobtanium mid bass drivers.

Okay, that answered most of my questions.

Nice room!

I would still pop that back panel off of the LS-6's and see where they have the bass management set. There still may be a lot to gain there. Someone may have just unplugged it allowing max bass levels.

How high are you allowing those subs to play?

I bet those X-Statiks sounded really good in that room.

[tomlinmgt]

Okay, that answered most of my questions.

Nice room!

I would still pop that back panel off of the LS-6's and see where they have the bass management set. There still may be a lot to gain there. Someone may have just unplugged it allowing max bass levels.

How high are you allowing those subs to play?

I bet those X-Statiks sounded really good in that room.

Thanks for the compliment. I'm a self professed acoustics geek and have been waaay deeper down that particular rabbit hole than any other the hifi hobby has to offer. Focusing on the room has consistently given me the best bang for the buck, and ensures I'm getting the all the "bang" my equipment has to offer. My listening space may seem like overkill for the modest equipment I can afford or even ostentatious to some (as I've been accused of being), but it's an investment that is likely to never depreciate since it's real estate equity...and there aren't hardly any components in a hifi system that you can expect to actually appreciate in value! 

Subs are playing up to 80 Hz with a -48db slope. The steeper the slope, the less I hear the issue at hand.

I'll have a look at the networks. These aren't AV123 units...they just use cabinets purchased from AV123. I'll try getting some good pictures and share what I find.

The x-Statiks were very nice, but lacked a few characteristics that are important to me. In a smaller room, they'd probably be more fulfilling. But we all know the x-Statiks aren't the last word in fidelity/performance in the GR Research lineup, and that's more the level I'm trying to reach. Even if the LS6's can get me 85% of what I heard from the X-Tremes...and it seems like I'm getting damn close (from what I can remember....it's been about six or seven years since I heard the X-Tremes at LSAF)...I'll be a satisfied man. 

[WGH]

Subs are playing up to 80 Hz...

That seems rather high for a sub. Where do the LS-6's start rolling off in your room? My stereo is completely different but my sub does go down to 15 Hz and is used to only fill in the lowest bass, it is adjusted to play up to 34 Hz, about where the main speakers start rolling off.

[tomlinmgt]

That seems rather high for a sub. Where do the LS-6's start rolling off in your room? My stereo is completely different but my sub does go down to 15 Hz and is used to only fill in the lowest bass, it is adjusted to play up to 34 Hz, about where the main speakers start rolling off.

I haven't measured the LS6's, so I can't say where they roll off.  The low frequency output is balanced, however, and it doesn't sound to me like they're unable to play in my room as low as they should be able to. I can say that in the track ""Temple Caves" by Mickey Hart, there's a big drum throughout the song that's hitting a 33-34 Hz fundamental and that's coming across with respectable weight and authority.  Would I prefer a little more weight and authority??? Yes, I certainly would. And that's the purpose of the subs...to augment what's there rather than fill in for what isn't. 

I've always run my mains full range and augment with subs. This gives me a response curve I prefer...which is tilted up a bit in the first octave in relation to the remainder of the frequency spectrum. And with the subs on a separate volume control with remote, I can tailor the bass output to my liking when a recording is bass shy. I'm particularly focused on getting a clean, strong reproduction in the 60-80Hz range where the tactile impact of the bass drum resides.  Being a drummer, reproducing the drums as accurately as possible is high priority to me. That means the bass drum and floor tom(s) HAVE to have an undeniable, authoritative and compelling tactile presence in the playback. If that's not there, I simply lose interest. Same for all the other drums...toms, snare, congas, timbales, etc...that tactile element HAS to be there or it will not keep my interest, period.

I don't make a habit of listening at high volume, but on occasion will take it up to live music event levels.  Obviously, provided the equipment is up to the task, this is going to deliver plenty of tactile energy. But I don't want to lose that when the volume comes down to more "reasonable" listening levels (80-90db range).  That's where the augmenting subs really make a big difference for me...they deliver that tactile sensation I crave without having to push the volume to concert levels. On top of that, I've yet to experience a speaker that produces its best low end in the same spot that it produces the most holographic, multi-dimensional.siund stage. So when I find that spot that delivers maximum image focus and sound stage dimensionality, it's always been for a trade off of low end prowess. Although in my new listening space, it's not as big a penalty as it has been in prior spaces where I've had systems.

[WGH]

I can say that in the track ""Temple Caves" by Mickey Hart, there's a big drum throughout the song that's hitting a 33-34 Hz fundamental and that's coming across with respectable weight and authority.

Temple Caves is one of my tune-up/demo cuts too, the big drum will fill a room if done right.


"Dynamic Drums", is the last track on the free Legacy Audio Music Sampler Volume 1. I got my CD in the Legacy room at the 2012 RMAF. This is the killer un-compressed drum track Legacy Audio was playing at lifelike levels in their showroom.
 
Here is a review of Dynamic Drums
http://thevinylanachronist.blogspot.com/2012/05/great-little-music-sampler-from-legacy.html

AC members can download a 44.1 kHz/16 bit zipped .flac file of "Dynamic Drums" here.

Wayne

[tomlinmgt]

Temple Caves is one of my tune-up/demo cuts too, the big drum will fill a room if done right.


"Dynamic Drums", is the last track on the free Legacy Audio Music Sampler Volume 1. I got my CD in the Legacy room at the 2012 RMAF. This is the killer un-compressed drum track Legacy Audio was playing at lifelike levels in their showroom.
 
Here is a review of Dynamic Drums
http://thevinylanachronist.blogspot.com/2012/05/great-little-music-sampler-from-legacy.html

AC members can download a 44.1 kHz/16 bit zipped .flac file of "Dynamic Drums" here.

Wayne

Got my copy right here...




...acquired at 2012 LSAF.  As a matter of fact, as soon as I left that show I got on the road and headed south to Austin to get the QLS-1's I mentioned earlier in this thread.  Man, that was a great time period in my hifi journey as I was about two years in at that point and my eyes were really getting opened up to how incredible a stellar hifi rig can sound.  And I damn sure miss LSAF when it looked like it did back then. Hell, it won't look like anything in Dallas anymore! 😂

Here's another very good drum's only track. Excellent recording and plenty of dynamic swings.




MBL was using that track in their demo room at SWAF this past spring.

[SoCalWJS]

I haven't measured the LS6's, so I can't say where they roll off. 

That is something that would be good to know. If it's not too difficult, run a frequency response on each channel separately and post the results without subs or EQ. Should give you a good deal of information on what should be done next.