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post #1 of 96 Old 08-19-2017, 01:12 PM - Thread Starter
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Mid-Bass Questions for the Experts and Gallery

I am lucky to have strong, linear acoustic response down to 25Hz in my system. So, "weak" mid-bass is not a factor. Out of curiosity, after seeing a number of people in pursuit of more mid-bass and using MBMs, I thought I'd experiment a bit with my system. Every room is different, but I was surprised at some of what I discovered, and thought I'd see how the experts here (LTD02, mtg90, and erichH) and some of you ring in.

I use two HTM-12s for L/R mains, and an 88 Special for a center, all in a sort of 2pi installation (see room in signature). I have four large subs in acoustic nominal locations cumulatively running about 1800 watts. The phase of the subs is adjusted for maximum spl when all running broadband pink noise. The room volume is over 8500 cu ft, and the MLP seating throw distance is 14.5'.

I measure via spatial averaging before xt32 calibration (subs alone, and also with each LCR to check the splice) then again after the calibration using the same measurement points for verification and tweaks. Based on that and mtg90's guidelines on the HTM-12s, I cross those at 50Hz. I cross the 88 Special at 60Hz.

I have noticed many here like to run the larger DIYSG models at full range. So, I experimented with that with my system. An A/B comparison is easy if you can easily turn off and on your subs and change your crossover settings. Content with strong mid-bass (kick drum, bass guitar, and movie) at moderate level was chosen for the experiment.

With the subs turned off and the LCRs running full range, the LF/mid-bass was nicely strong. I certainly knew it would remain so if played loudly, but I didn't do so to be cautious with the LCRs.

With the LCRs left in full range and the subs turned on, a significant, audible, reduction in mid-bass was evident. If the LCRs were returned to their respective crossover points and subs left on, the strong mid-bass returned.

I would think that this reduction in mid-bass occurred due to phase issues between the LCRs and subs at various and unpredictable frequencies in that region below the 50Hz crossover. I would also speculate that the xt32 calibration is adjusting in the time domain to nominalize the LCR/Sub splice when the crossover is engaged.

Experts, dive in here.

I bring this up on the chance that some here who feel they lack mid-bass are experiencing the same thing that I discovered since they are running full range on their LCRs. If not already tried, maybe the same experiment is worthwhile to see what your room and system do in the different configurations.

FWIW

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post #2 of 96 Old 08-19-2017, 02:26 PM
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Room correction does its best and you can have very good results in some rooms. Other rooms have nulls no matter how well one tries to remedy it. Still other may have perfect frequency response but suffer from weak tactile response. Some prefer their movie watching experience to resemble a cage match. Regardless of which category you fall in, MBM's offer correction to your FR, TR or both and due to their small footprint can be a very precise solution. There's a lot of octaves to cover now. I also believe small, tightly sealed rooms are at a disadvantage when compared to large, open rooms.
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post #3 of 96 Old 08-19-2017, 03:35 PM - Thread Starter
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Originally Posted by coolrda View Post
Room correction does its best and you can have very good results in some rooms. Other rooms have nulls no matter how well one tries to remedy it. Still other may have perfect frequency response but suffer from weak tactile response. Some prefer their movie watching experience to resemble a cage match. Regardless of which category you fall in, MBM's offer correction to your FR, TR or both and due to their small footprint can be a very precise solution. There's a lot of octaves to cover now. I also believe small, tightly sealed rooms are at a disadvantage when compared to large, open rooms.
By "tactile response" do you mean transient response time; "quickness" so that short duration, high amplitude events "impress" (for lack of a better term that I can think of)?
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post #4 of 96 Old 08-19-2017, 04:29 PM
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I run my mains full range for that reason of the added impact in the midbass and I also get the smoothest FR running then full range vs small. I mainly listen to music and also only have a LRC and most of the time listen in stereo. So anyway I know that most people will recommend not to do that, I have found that is what I prefer and I have tried a lot of different settings and trial and error with using my mains set to small.

Also the reason you notice the reduced bass/midbass when running the LR full range and engaged the subs is you need to change the subwoofer distance or try changing subwoofer polarity to get the smoothest FR. You are getting a cancelation. Just like I can not just switch my mains to small and have the smoothest FR. The settings are much different when using full range vs small and blending with a subwoofer.

I also prefer running a higher cross over than many people. I see a lot of people use 80hz but I usually use 100hz and at times I have used as high as 150hz so using a cross over that high and running the mains small really takes away the midbass from the mains for me.

I have a slew of different subs so I am usually trying something different from time to time from sealed to ported to horn loaded subs. The current subs I am using are sealed and ported mixed. UM18s, Submersive, XS30 and B&C 18TBW100 ported for midbass. The UM18 and B&C are directly behind my MLP as near field subs and prefer them to the feel of the Crowson. The Submersive and XS30 are far-field.

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post #5 of 96 Old 08-19-2017, 04:53 PM - Thread Starter
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I run my mains full range for that reason of the added impact in the midbass and I also get the smoothest FR running then full range vs small. I mainly listen to music and also only have a LRC and most of the time listen in stereo. So anyway I know that most people will recommend not to do that, I have found that is what I prefer and I have tried a lot of different settings and trial and error with using my mains set to small.

Also the reason you notice the reduced bass/midbass when running the LR full range and engaged the subs is you need to change the subwoofer distance or try changing subwoofer polarity to get the smoothest FR. You are getting a cancelation. Just like I can not just switch my mains to small and have the smoothest FR. The settings are much different when using full range vs small and blending with a subwoofer.
Yes, you sought out what works with your complex system in your room.

I think you make a good point in the second paragraph. Most AVRs/AVCs have LFE/subwoofer phase adjustment in their menu settings which I could use to find a setting that would dial the subs into phase with the LCRs. Since I've independently dialed the subs amongst themselves, only sub to LCR phase would be affected by adjusting sub phase in the AVC settings. I'll have to try that.

In his response above @coolrda mentioned "weak tactile response"--which I think refers to transient response. The system you have of many subs (and likely mine, too) probably helps retain quick transient response since one or two subs are not having to do all the rapid excursion to reproduce the transient. Just a theory.

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post #6 of 96 Old 08-19-2017, 07:47 PM
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Yeah if Audyssey initially did its calculations assuming the mains would be run as small then by running them full range you no longer have the right integration with your subs as the high pass filter or in this case lack thereof caused change the in mains phase response that is not accounted for. So with a little experimenting with the subwoofer distance/delay setting in the AVR you should be able to bring it back into alignment.
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post #7 of 96 Old 08-20-2017, 10:11 PM
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Quote:
Originally Posted by Cam Man View Post
By "tactile response" do you mean transient response time; "quickness" so that short duration, high amplitude events "impress" (for lack of a better term that I can think of)?
The impact on our body that we feel. The feel of content as produced from loudspeakers, subwoofers, transducers/actuators and the currently popular MBM's. Of course with all of these there's a personal preference that goes beyond reference level as well as other factors such as room makeup and cab placements.
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post #8 of 96 Old 08-21-2017, 06:16 AM
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I have a link to Matt's thread in my sig about subwoofer integration. I also recommend this article from Rythmic. Both helped me understand how to get my subs integrated properly with my mains. http://www.rythmikaudio.com/phase1.html

I love the idea of Moar midbass and have plenty of it with my subs crossed at 120hz. Sometimes I wonder if those who are seeking it have their existing gear set up to get the most out of it.
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post #9 of 96 Old 08-21-2017, 09:54 AM
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@Cam Man

Have you tried doing an Audyssey run with the speakers set to full range with the sub? I'm sure it would correct the delays for you.

Do you measure your post-EQ response with Omnimic or REW?
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post #10 of 96 Old 08-21-2017, 10:32 AM - Thread Starter
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@Cam Man

Have you tried doing an Audyssey run with the speakers set to full range with the sub? I'm sure it would correct the delays for you.

Do you measure your post-EQ response with Omnimic or REW?
I have not done a full range Audyssey run because I doubt I would decide to risk leaving the LCRs to operate at full range at high spl in this large room. The exception might be listening to 2-channel music, but I really don't have a need to since running crossed has such good results. I use Omnimic.

Wait a minute...when you do an Audyssey calibration run, where you have the crossovers set doesn't matter. By default for a calibration run, they are at full range. Based on the Audyssey criteria (presumably the point where the speaker rolls off -3dB) it recommends and sets the crossover at that frequency. You can change that crossover point if your wish, but I don't know if much is done with time domain below that crossover it chooses. That may be the problem that arises with their phase with subs when running at full range, depending on the particular room and layout.

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post #11 of 96 Old 08-21-2017, 10:54 AM
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I have not done a full range Audyssey run because I doubt I would decide to risk leaving the LCRs to operate at full range at high spl in this large room. The exception might be listening to 2-channel music, but I really don't have a need to since running crossed has such good results. I use Omnimic.
If you have it, I suggest using the Omnimic 5.1 test tone disc. It's available from Parts Express. Might be ~$20 but very much worth it!

You can try manually setting the delay with the mains set full range and use the impulse graph to get the timing right. You shouldn't need high SPL's whatsoever to do this.
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post #12 of 96 Old 08-21-2017, 11:08 AM - Thread Starter
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If you have it, I suggest using the Omnimic 5.1 test tone disc. It's available from Parts Express. Might be ~$20 but very much worth it!


You can try manually setting the delay with the mains set full range and use the impulse graph to get the timing right. You shouldn't need high SPL's whatsoever to do this.
BTW, I added an edit after you read my post.

I have the disc, and that's how I am able to measure.

I wrote poorly. I didn't mean to say I was concerned about full range during the measuring. I would not run full range in this room with the HTM-12s with movie content at high levels. There's just no need to.
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post #13 of 96 Old 08-21-2017, 11:58 AM
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Ah, okay. Just catching up now.

So what exactly are you trying to experience? More midbass, better midbass? It's hard to figure out without more data. Can you post a frequency response with separate measurements of the speakers, subs and combined?

There are so many reasons why midbass comes up in discussion and then some people even make "MBM's" to try and enhance it. My feelings are that midbass is covered by the mains. Not the subwoofer. One should have beefy mains to produce nice midbass. Let the subwoofer do subwoofer duty. Although every one seems to have their own definition of what "midbass" is. The popular opinion seems to make a focal point on the 50-70hz range. This is certainly punchy but not true midbass, imho.

If you want that cinema/IMAX midbass, you should build a dual 15-18" cab with pro drivers and integrate it into your subwoofer system. That's one way to do it, at least.


Then there is that whole "small room acoustics" thing that is sort of a big deal...
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post #14 of 96 Old 08-21-2017, 12:13 PM
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This song is what I think of when talking midbass.

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post #15 of 96 Old 08-21-2017, 12:17 PM - Thread Starter
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Ah, okay. Just catching up now.

So what exactly are you trying to experience? More midbass, better midbass? It's hard to figure out without more data. Can you post a frequency response with separate measurements of the speakers, subs and combined?

There are so many reasons why midbass comes up in discussion and then some people even make "MBM's" to try and enhance it. My feelings are that midbass is covered by the mains. Not the subwoofer. One should have beefy mains to produce nice midbass. Let the subwoofer do subwoofer duty. Although every one seems to have their own definition of what "midbass" is. The popular opinion seems to make a focal point on the 50-70hz range. This is certainly punchy but not true midbass, imho.

If you want that cinema/IMAX midbass, you should build a dual 15-18" cab with pro drivers and integrate it into your subwoofer system. That's one way to do it, at least.


Then there is that whole "small room acoustics" thing that is sort of a big deal...
I'm in fine shape. I was just trying to be a good Samaritan by mentioning for discussion what I had discovered. As described in my original post, in case some folks felt as though their mid-bass was lacking, they might want to try different configurations to test (in case they haven't already).

While just experimenting, I stumbled upon a configuration in my system that would result in weaker mid-bass. It's moot for me because that is not a configuration I run in. Like many, I thought I'd try the full range with the subs to see if I heard a difference in the mid-bass. If anything, I expected to hear an excess of mid-bass since it's not EQd for that configuration. I didn't expect to hear less. Since I was "surprised," I thought I'd relate my experience on the chance that others had settled into a similar situation unknowingly. That's all.
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post #16 of 96 Old 08-21-2017, 01:40 PM
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Sorry bout that. To eager to get to 'build stuff' around these parts.

Thanks for sharing! Always interested in what you have to post.
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post #17 of 96 Old 08-21-2017, 05:09 PM - Thread Starter
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Sorry bout that. To eager to get to 'build stuff' around these parts.

Thanks for sharing! Always interested in what you have to post.
Ha, no worries. Thank you for thinking of trying to help me. The only time I find myself doubting my system is when I let myself get fooled by some poor recordings. I so wish that music engineers would mix like film mixers do. The SQ of even most CD releases of movie scores are p*** poor compared to the SQ of them on the BD. That's another thread, though.
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post #18 of 96 Old 08-21-2017, 06:56 PM
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This song is what I think of when talking midbass.

https://m.youtube.com/watch?v=u06DpcFXc4U
Heard this at 16 on Klipschorns with a Carver M 1.0T amplifier driven just to the edge of clipping, in a small room.

Forever ruined.

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, implusivity, uncontrolled or repeated movements.
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post #19 of 96 Old 08-22-2017, 08:59 AM
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Ha, no worries. Thank you for thinking of trying to help me. The only time I find myself doubting my system is when I let myself get fooled by some poor recordings. I so wish that music engineers would mix like film mixers do. The SQ of even most CD releases of movie scores are p*** poor compared to the SQ of them on the BD. That's another thread, though.
I tell ya, that's one of the worst things about having a really nice speaker system is when it is too revealing. Things that used to sound good, don't. Garbage in, garbage out. Ugh!
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post #20 of 96 Old 08-22-2017, 10:48 AM
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@Cam Man
do you happen to have a waterfall/time domain response of the two?

Listen. It's All Good.
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post #21 of 96 Old 08-22-2017, 11:56 AM - Thread Starter
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@Cam Man
do you happen to have a waterfall/time domain response of the two?
I don't. At least not yet.
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post #22 of 96 Old 08-22-2017, 06:10 PM
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I didn't do so to be cautious with the LCRs, I cross those at 50Hz.
My condolences.

You shoulda went 4-way active sealed. My mains are flat from 2Hz to 40kHz


I'm 100% sure that if I took it outside the sweep would be even smoother...
and that's just my mains, my subs and MBM's are beefier (and ran about 15db hotter...)

Who wants to run their LCR's 15db hot @4khz just to get some more mid-bass, when you CAN HAVE dedicated MBM's for that task?

The tonality of the LCR needs to be flat from DC to Infinity, otherwise things will sound "rolled off", or bloated if you try to apply a house curve to the LCR's or try force ported's below their tuning.

Some people like their bass to kill them. Even a single SEOS can kill your ears, but try killing your ears at 20hz... that's no easy task, even for 8 horned 18's! Never enough bass. MOAR!

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With the LCRs left in full range and the subs turned on, a significant, audible, reduction in mid-bass was evident. If the LCRs were returned to their respective crossover points and subs left on, the strong mid-bass returned.

I would think that this reduction in mid-bass occurred due to phase issues between the LCRs and subs at various and unpredictable frequencies in that region below the 50Hz crossover.
Are your mains ported? at 50hz?
As I understand, ported boxes have a phase shift below tuning, so I wouldn't be surprised that forcing it to play to DC might cause all sorts of phase/SPL/driver issues. Sealed doesn't have this issue, it only bottoms out earlier. Everyone needs 32 sealed 32's. Just add more... Problem solved!
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post #23 of 96 Old 08-22-2017, 07:47 PM - Thread Starter
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@bassthathz...and what way is it exactly that your reply/post is helpful to this conversation? No one here has expressed a problem for which you seem to be offering an unsolicited solution. The discussion herein has been in the spirit of the earliest traditions of AVS Forum.

If you have a constructive suggestion rather than a...whatever that was....you are welcomed to make it. Otherwise, nobody here has a need to bear the burden of your bombastic bass. You can put that bass back in your pants. Just joking.
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post #24 of 96 Old 08-22-2017, 11:05 PM
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No one here has expressed a problem.
You expressed your problem right here in the first post. Which was the whole point of making this thread, I assume.

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With the LCRs left in full range and the subs turned on, a significant, audible, reduction in mid-bass was evident. If the LCRs were returned to their respective crossover points and subs left on, the strong mid-bass returned.
Sounds like a problem to me...
Who on earth would run ported boxes (be it mains or subs) full range?
It's been known since forever, that ported boxes need a HPF (Unless we are talking a 1Hz tuned box the size of a house...)

Do you have measurements you can share for this supposed reduction of mid-bass?

Crossovers cause phase shift for sure, at least if we are talking DCX's, inukes, entry level crowns, minidsp's and any other IIR-based dsp (which is most of them.)

I'm not 100% sure but I'd imagine the ports have phase shift as well, below their tuning.

Although all of this is at a reduced SPL, of course...

We have no idea what settings you've used for the time delays of your mains or the sub, nor their precise distance.
The further object should have no delay, and the closest object should have the most delay, of course...

We also don't have a birds-eye blueprint of your room with the exact locations of the sub(s).
Maybe your sub is in a corner and the mirrored main is firing into a fire place and the other side is firing into an open L-shaped room.

We need actual data to make a technical/informed conclusion/opinion, let alone an expert one, otherwise we are just blindly swinging at a pinata here.
I could say that my system has strong or weak mid-bass too... it's all relative to the number of emptied beer cans.

Properly place and time align your stuff. Don't overlap XO's by large amounts (if you don't want cancellation). EQ only if needed. Don't run horned or ported boxes full-range (use a HPF). Problem found. Problem solved!

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post #25 of 96 Old 08-23-2017, 06:38 AM - Thread Starter
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@BassThatHz , I commend you for your enthusiasm to help fellow members when you interpret a post as a description of a problem and an appeal for help. That is not the situation I am in, nor is that the subject of this thread. In the first two sentences of the original post I state:

"I am lucky to have strong, linear acoustic response down to 25Hz in my system. So, "weak" mid-bass is not a factor."

This means I don't have a problem in my system that would be defined by me subjectively (or objectively if measured) as "weak mid-bass." "Linear" for me is defined as +/-3dB of the target curve utilized in the room.

It is a discussion thread regarding why many people, especially those here in the DIY field, feel they don't have as much mid-bass as they would like. I was curious as to why they felt this way; what was causing this perception. I asked myself whether this was a real, measurable problem that exists or is it just a subjective perception.

So, I was referring to what other people describe as a "problem," although it may well just be a personal preference as part of the fun of being an enthusiast. I experimented with settings in my system to see if I could replicate the shortcoming they described. I was, but I didn't know if the way I created the "problem" in experimentation is what was happening in their system. On the chance that it was, I brought it to attention with this thread.

With regards to your extensive descriptions and notes on achieving the VLB for your system/room, that is another very interesting subject. Back in 2014 I joined an excellent discussion thread that AVS Associate Editor imagic began titled "Bass: How Low Should You Go?

Upon finding this thread, I reached out to one of the major sound mixing facilities about VLB content in cinema and BD mixes with a lot of questions. My questions were forwarded all the way to an engineer at the facility who responded over numerous emails with long, detailed responses. Somewhat due to the fact that I worked in the movie industry, he trusted me with a ton of time and information. The trade-off was that I could not quote him directly or identify his company, since he was responding officially from the company. But the company is big. As big and accomplished as there is in the industry. Think big and high. I entered the discussion in that thread with a report on the feedback from the mixing engineer.

It is there that I explain how I landed (coincidentally and pragmatically) at a low end of 25Hz in my system, and how that coincides with specific SMPTE specs for cinema dubbing stages (mixing stages). There is an excellent, robust discussion there on the subject with many making excellent points. You might enjoy taking a look.

That thread begins here: https://www.avsforum.com/forum/113-su...l#post24714716

My first post is here (#357, page 12): https://www.avsforum.com/forum/113-su...l#post26772641 and discussion continues on that onto page 13.

Cheers.
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post #26 of 96 Old 08-23-2017, 06:55 AM
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I'm currently in the process of setting up my system to maximize midbass but frankly it totally depends on the power and the design of the speaker as far as I can tell.

I will be useing 3 JBL 4647(JBL 2226HPL) and I might add my "doom box" a JBL 4648A-8(2 JBL 2226J) to the mix. These output solidly down to ~30hz but shine 35hz and up. They are teamed up with two JBL Synthesis S1S(they use the JBL 2245H) for anything under that 35hz area down to about 18hz which is what JBL says it'll work fine to. You can see everything is not setup correctly just yet this is just me testing to make sure all the tech is working.

I should get a lot of midbass out of my system I'm powering all of them with a Inuke NU3000DSP.

Here is a picture attached of all the crazy that is going on, also I should note this setup is frankly cheap.
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post #27 of 96 Old 08-23-2017, 07:49 AM - Thread Starter
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Quote:
Originally Posted by DocOrange88 View Post
I'm currently in the process of setting up my system to maximize midbass but frankly it totally depends on the power and the design of the speaker as far as I can tell.

I will be useing 3 JBL 4647(JBL 2226HPL) and I might add my "doom box" a JBL 4648A-8(2 JBL 2226J) to the mix. These output solidly down to ~30hz but shine 35hz and up. They are teamed up with two JBL Synthesis S1S(they use the JBL 2245H) for anything under that 35hz area down to about 18hz which is what JBL says it'll work fine to. You can see everything is not setup correctly just yet this is just me testing to make sure all the tech is working.

I should get a lot of midbass out of my system I'm powering all of them with a Inuke NU3000DSP.

Here is a picture attached of all the crazy that is going on, also I should note this setup is frankly cheap.

Hi...If the S1S subs are the current S1SEX, they are THX Ultra2 certified which means they will reach 20Hz for sure in a chamber. The older S1S, IIRC, were THX Ultra certified, and started unloading at about 35Hz presuming room gain. Still, they are capable of very high performance. Four of those in any room under 9000 cu feet would do very well with placement and EQ.


Looks like a fun project.
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post #28 of 96 Old 08-23-2017, 08:18 AM - Thread Starter
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Quote:
Originally Posted by DocOrange88 View Post
I'm currently in the process of setting up my system to maximize midbass but frankly it totally depends on the power and the design of the speaker as far as I can tell.

I will be useing 3 JBL 4647(JBL 2226HPL) and I might add my "doom box" a JBL 4648A-8(2 JBL 2226J) to the mix. These output solidly down to ~30hz but shine 35hz and up. They are teamed up with two JBL Synthesis S1S(they use the JBL 2245H) for anything under that 35hz area down to about 18hz which is what JBL says it'll work fine to. You can see everything is not setup correctly just yet this is just me testing to make sure all the tech is working.

I should get a lot of midbass out of my system I'm powering all of them with a Inuke NU3000DSP.

Here is a picture attached of all the crazy that is going on, also I should note this setup is frankly cheap.
What is that huge black processor in the middle of the image?
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post #29 of 96 Old 08-23-2017, 08:50 AM
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Quote:
Originally Posted by Cam Man View Post
It is there that I explain how I landed (coincidentally and pragmatically) at a low end of 25Hz in my system, and how that coincides with specific SMPTE specs for cinema dubbing stages (mixing stages).
The "problem" is that "small room" acoustics are very different from cinema dubbing stages. There is deep bass content in movies now that you'll never hear in a theater, but which can add dramatically to the experience in a home theater. But you have to go lower than 25Hz.
But now we're not talking about mid-bass, so, back to your point: when I added one MBM (Behringer 1200D), it made a big difference. When I tried to integrate a second, it just cancelled the effect of the first. So I use one.
Which is why measurements, experimentation, and patience are so important.
Michael

Did you really need to quote that entire post in your reply?
Welcome to AVS - Get out while you still can!
Don't guess, measure: https://www.avsforum.com/forum/91-au...l#post22789786
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post #30 of 96 Old 08-23-2017, 09:32 AM
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These "small room acoustics" are what mess up the midbass, actually.

It's much harder to recreate that theatrical bass sound at home because our response in that meaty 60-250hz range are usually s**t.
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Last edited by Scott Simonian; 08-23-2017 at 09:51 AM.
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