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Bobby

Need a little help in the bass region

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Hi guys,

Need advice on the bass system for my HT. Have six ultimax um-18 in ported cabs on the front in a array and think  about modifying them and put them in sealed boxes,for faster and thighter bass, better group delay and for easier integration,I think. Is a total external volume of about 7 cft sealed box( that is the easiest practical volume after modification)to big for the um18? I saw that on databass it was tested in a 6,16 cft external, and Dayton recommendations is an internal of 4,2 net volume. I have a few Magnum-12 drivers (diysoundgroup)from another project and want to integrate them in a system as midbass modules with the ultimax to split the frequency, the um-18 to about 50Hz and the magnums from 50 to 120Hz, from a single LFE output and split with a miniDsp. The room is about 23’,16’,7,5’ all concrete walls,floor and ceiling; on the back wall is an porous absorber 2’ thick,floor to ceiling,wall to wall.

I ask you if going from ported to sealed is a good ideea? forgot to say that from the six ported boxes,two of them that I put in the center of the grid are smaller And after measurements with rew they look a little bit different that the bigger left and right arrays .If I don’t go sealed,I don’t have the space for the Magnums and the two way bass system.Do you think this will work?

 

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You might wanna ask this question on AVS again, but unless your cab is severely mistuned, the issues you‘re hearing are likely room issues.

I have no experience with the um-18, but apparently it‘s also pretty capable in the mid-bass region. I‘m not sure if dropping those drivers in sealed cabs would yield your desired improvements.

I have seen other people using (multiple) um-18s seeking for better misbass performance, which makes me wonder why not go for the 21ds115 or similar instead. I know in the states they‘re similarly priced and you‘ll lose a bit of deep bass (displacement), but you‘ll gain a lot of sensitivity.

If those magnum drivers are high sensitivity drivers, I‘d give them a shot. Should work rather nicely in sealed cabs.

What other subs are you using in your setup, for which you‘re hoping for better integration?

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Could be room issues. Its pretty easy to stuff your ports and get a sense of what a sealed box sounds like. The larger box volume won't negatively affect the midbass at all. Only really increases efficiency down low. Just make sure to turn off your high pass filter once you seal it... and go easy at first!

But what you really might just need it to figure out if you have some standing waves in that room that negatively affect the bass. Just move the subs and see what happens. I would also consider getting a higher efficiency 18" driver and just switching that. But before doing anything costly, what sort of power are you running to your subwoofers?

 

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22 hours ago, peniku8 said:

You might wanna ask this question on AVS again, but unless your cab is severely mistuned, the issues you‘re hearing are likely room issues.

I have no experience with the um-18, but apparently it‘s also pretty capable in the mid-bass region. I‘m not sure if dropping those drivers in sealed cabs would yield your desired improvements.

I have seen other people using (multiple) um-18s seeking for better misbass performance, which makes me wonder why not go for the 21ds115 or similar instead. I know in the states they‘re similarly priced and you‘ll lose a bit of deep bass (displacement), but you‘ll gain a lot of sensitivity.

If those magnum drivers are high sensitivity drivers, I‘d give them a shot. Should work rather nicely in sealed cabs.

What other subs are you using in your setup, for which you‘re hoping for better integration?

I can’t switch the drivers no more, I will stay with the um’s and the Magnums, that are pretty sensitive drivers and give it a shot; I hope to integrate them with the Um’s and split the frequency range in two, say 5-50Hz to the Um’s and 50-120Hz to the Magnums.

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25 minutes ago, Bobby said:

I can’t switch the drivers no more, I will stay with the um’s and the Magnums, that are pretty sensitive drivers and give it a shot; I hope to integrate them with the Um’s and split the frequency range in two, say 5-50Hz to the Um’s and 50-120Hz to the Magnums.

Ported subs are easy to integrate if they are the lowest playing speakers in the system. If you have ported subs and want to run something below that (like sealed or other deeper ported subs), you'll have a hard time on doing so. FIR filtering might be the only solution, at the cost of delay and ringing. But since that's not the case you won't have to worry about that.

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10 hours ago, Kyle said:

Could be room issues. Its pretty easy to stuff your ports and get a sense of what a sealed box sounds like. The larger box volume won't negative affect the midbass at all. Only really increases efficiency down low. Just make sure to turn off your high pass filter once you seal it... and go easy at first!

But what you really might just need it to figure out if you have some standing waves in that room that negatively affect the bass. Just move the subs and see what happens. I would also consider getting a higher efficiency 18" driver and just switching that. But before doing anything costly, what sort of power are you running to your subwoofers?

 

Have three inukes6000 dsp, one channel for each driver.I will take some more measurements with rew to see what happened.It can still be a room issue to, but since I installed the huge absorber on the back wall the standing waves are diminished pretty much.I always felt that the ported boxes sound boomy sometimes in my room; is a sealed cab gone to sound different in room then the ported box? for budget reasons,can’t sell the um-18 and go with another driver, just modify the ported and make smaller sealed boxes to have space to accommodate the Magnums-12 to take care for the midbass.Do you think that approximately 7 cft exterior volume is ok fot the Ultimax in sealed enclosure?

 

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10 minutes ago, peniku8 said:

Ported subs are easy to integrate if they are the lowest playing speakers in the system. If you have ported subs and want to run something below that (like sealed or other deeper ported subs), you'll have a hard time on doing so. FIR filtering might be the only solution, at the cost of delay and ringing. But since that's not the case you won't have to worry about that.

Thank you!

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Are you using some kind of EQ (manual or auto) right now? 

Do you have any idea how much output you need vs. what you have in the deep bass?  Switching to sealed will give up a lot of it, and you might want to use some EQ to bring response up, at the cost of more headroom.

The other issue will be the integration complexity, especially if the Magnums-12s are ported, as noted in earlier posts.  Will all the different subs be placed close to one another?  That definitely makes it easier.  Will sealed vs. vented Magnum 12s give you enough output?  If so, this will give you the most flexibility with respect to crossover.

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Have some miniDsp for EQ; my goal is to achieve about 130db at 20 and 120db at 10hz in room.Do you think it’s possible with 6 sealed Ultimax and 4 sealed Magnums? What do you think is the ideal enclosure volume for the ultimax?(I’m not familiar with winISD yet)
Want to put the Magnums right beside the Ultimax when sealed.Here is a pic with the actual setup.

4140DA63-7A7F-4CA6-ACC9-E5F3B642AE6E.jpeg

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On 6/25/2020 at 1:06 AM, Kyle said:

Could be room issues. Its pretty easy to stuff your ports and get a sense of what a sealed box sounds like. The larger box volume won't negatively affect the midbass at all. Only really increases efficiency down low. Just make sure to turn off your high pass filter once you seal it... and go easy at first!

But what you really might just need it to figure out if you have some standing waves in that room that negatively affect the bass. Just move the subs and see what happens. I would also consider getting a higher efficiency 18" driver and just switching that. But before doing anything costly, what sort of power are you running to your subwoofers?

 

I sealed the ports,like you suggested, and the overall result is better than before; the abundance of room shaking Low frequency and TR in the couch is diminished,but still there.Next step is to modify the cabs to have the same internal volume on al six,sealed and see the result; maybe the ULF region and lot of TR is not much of my taste, do you think that six or eight high efficiency 18”, like the Lavoce saf 184.03 in sealed cabs can give me the best of both worlds, enough deep bass and much better punch in the midbass? Think that the small concrete walls room has a lot of gain that made the ported um18 to overkill.I read that the Lavoce is almost as good as the b&c at a lower price.

 

 

 

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Hi @Bobby.  Please note my earlier post about EQ and note whether or not you use it, and how you use it if you do.

Application of EQ can both make or break the sound of a system.  If you use any kind of EQ (auto or manual), try shutting it off (except for essential things like protective high pass filters).  If you don't use EQ, you might try adding a gentle shelf filter in the iNukes to attenuate the deep bass and ULF relative to the mid-bass.  If you can measure your response in the room using e.g. REW, you might try measuring in a few different spots to see where you might have room resonances that might also benefit from EQ attenuation.  All of this can be done before spending lots of time and money replacing equipment, and it might give you insight into what changes will actually benefit you the most.

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I use a miniDsp and after EQ,the response is pretty flat from 10 to 120Hz;Kyle mentioned a few posts above that I need to turn off the HPF after sealing the ports, I’m a little confused now, do sealed subs need an HPF? I will try to set a 5 to 10db peak filter in the minidsp in the 60Hz region(??) to see if the um-18s can give me what I’m looking for.How do you think would the Lavoces perform compared to the UMs if I decided to make the switch ( or any other pro driver with equal specs) in sealed cabs? Do I loose completely the ULF and win better midbass?

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Can you post your EQ settings?  Also, can you post any measurement data you have (preferably before EQ is applied)?  Data for measurements taken at multiple locations is even better.

In my experience "frequency response" measured in-room, especially at only a single location, is not a reliable direct indicator of subjective sound quality.  It's not that frequency response isn't important.  In fact, FR matters a lot!  The problem is that the in-room FR at the seat is not really the FR that you hear.  EQ that makes in-room FR appear "flatter" can actually degrade sound quality.  Measurements at multiple locations can help reveal and distinguish modal room resonances from interference effects.  Modal resonances are audible and likely to benefit from EQ treatment.  Interference effects are less audible and much more difficult to treat using EQ.

Other than that, I suggest experimenting only with broad (low-Q) changes, mostly cuts rather than boosts.  Often times, cutting bass in the right place (i.e. where cut is actually needed) can paradoxically make it seem louder and more intense.  Your 5-10 dB peaking filter at 60 Hz is likely to just emphasize whatever FR problems exists in that region, which may make things better or worse.  Applying a broad dip centered at the "inductance hump" for your sub may be helpful if you have any outdoor measurement data to refer to, but this hump is hard to see in an in-room measurement.

At the end of the day, the sound quality of the result is what's important, not how the FR picture looks.  Always listen to the result of any EQ you apply and consider playing with the gain to see if you can find a balance point.

====

Sealed subs don't necessarily need a HPF like vented subs do.  Below their tuning frequency, vented subs essentially behave like leaky boxes and excursion tends to rise very rapidly for the driver, even though it's not making much useful sound.  Driver motion in sealed subs is constrained by the air cushion.

As for what you get with pro-style drivers vs. UM18s, the answer is complicated.  The differences are as follows:

(1) Headroom/output capability:  This is important if you are running the system hard and are constrained by output capability.  The pro drivers will have quite a bit more mid-bass output than the UM18s.  In sealed cabinets, they will have less deep bass and ULF output.  With that said, you seem to have a lot of output capability in there, so unless you're really hardcore, you're probably not constrained by output capability.

(2) Innate/baseline frequency response differences:  This affects the sound without EQ and also with EQ to the extent that you don't completely compensate for the difference in response shapes.  Pro style drivers will typically give an FR with more mid-bass and less deep bass.  A sealed sub will give up even more deep bass, but may allow ULF output to lower frequencies than your current vented subs are capable of.  Pro style subs often (but not always) have better management of inductance, which reduces "humping" that often shows up in the 40-60 Hz range and can overemphasize this region at the expense of everything else.  Realize that, in principle, innate frequency differences can be compensated for using EQ, but in practice this can be difficult.  So even when using EQ, it might be advantageous to start with a baseline that has more mid-bass emphasis and maybe less severe inductance hump centered at a higher frequency.

(3) Non-linear effects, in terms of distortion and compression:  Different types of drivers exhibit different non-linear behaviors.  The is more of a driver-by-driver thing, but inductance non-linearity may be quite important here.  So drivers that manage inductance better are also less likely to exhibit inductance non-linearity.  Note that non-linear compression is not necessarily the same at all frequencies, so non-linear effects can involve frequency response changing with driver level.  For example, the "inductance hump" might be diminished at high drive levels relative to low drive levels.  EQ (which acts linearly) cannot compensate for these non-linear effects.  So to the extent these things matter (and unfortunately, there's no simple answer here), drivers with lower distortion and better managed inductance are likely to sound better.

====

So probably the first thing you want to figure out is whether you are constrained by output capability.  With 6 ported 18s in there, I rather doubt it, but if you are in fact constrained in the mid-bass and have extra headroom in the deep bass and ULF, then moving to more pro-style subs is likely to help.  If you have enough headroom, then you can try experimenting with EQ (or with turning it off! ) to see if you can improve things that way.  If not, then a move to pro-style subs could still help for reasons (2) and/or (3) above.

FWIW, I do lean toward recommending pro-style subs in general because small listening rooms tend to provide substantial boundary gain to compensate for the relative deficiency of bottom-end output with such subs and because they almost always handle the higher mid-bass frequencies better.  Pro-style subs have also become quite popular in the DIY community, and a lot of people swear that they sound better or "slam" harder than traditional home-theater style subs.  This is likely due to some combination of (2) and (3) above, and I mostly lean toward (2).  Of course, you've already invested a lot of time and money in your existing setup, so IMO it's worth trying to get the best out of it before changing it.

Good luck with whatever you do!

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Will post some measurements on Sunday cause I’m out of town until than.Thanks a lot for your time and help, I really appreciate it;I really had invested a lot of time and money in my theater, learned a lot and have so much more to learn and I don’t want to give up before the bass ,that is so important to be  done right , is not so how I imagine to be to my ears.

Very through and very interesting topic what you said about FR in room vs what you hear, but I think it depends from one room to another; A very nice guy, AVS member, that helped me to understand REW , crate filters in rew for my inukes that I applied and the frequency response was perfectly flat from port tuning to 120Hz, but”paradoxically “ how you say, it sound very, very bad in room, the abundance of ULF was so present, I couldn’t turn the volume more than-10db on Wotw, pod scene for example, I think the house was falling apart.Since I sealed provisional the subs and applied just a little EQ-3 points, it sounds better but thhis loud bass from the ported, that was sometimes fun too, disappeared.

Although I put a two feet thick absorber on the whole back wall, I have this problems in the ULF, that hope to solve.

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Hi guys!

modified the cabs from ported to sealed ( approx. 6,2 cuft net internal volume) and don’t loose much on ULF, not so loud like the ported around 20Hz, but now extended until 10 and under.Will attach a measurement pic ( black is raw and green is with EQ).I realized that I will never achieve the midbass that I’m looking for with the UMs, no matter what I do and how the in room measurements look like, they are sluggish in my opinion and so I made the decision,on peniku8 and Kyle’s suggestion,to sell the UMs and buy some high efficiency drivers.

 Don’t know if I can afford to buy B&C,but I find the Lavoce saf184.03 for 200€ and can buy 8 of them( can accommodate another two sealed cabs behind the screen)Presume the 8 can give me the kickbass that I’m looking for and makes a drum solo sound more real life like and think that output is not a problem, but do they reach 20Hz and a little bit under in the ULF? or are there alternatives to the Lavoce until 300 per driver?

 

 

8856BE1B-B4DF-44F3-A7C6-DB07E0406D9A.jpeg

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6 hours ago, Bobby said:

Don’t know if I can afford to buy B&C,but I find the Lavoce saf184.03 for 200€ and can buy 8 of them( can accommodate another two sealed cabs behind the screen)Presume the 8 can give me the kickbass that I’m looking for and makes a drum solo sound more real life like and think that output is not a problem, but do they reach 20Hz and a little bit under in the ULF? or are there alternatives to the Lavoce until 300 per driver?

 

200€ for the 184.03 is very good, it's about 240 where I usually order. 8 sealed 18" drivers with some 15mm of one way excursion will probably be enough to dig below 20Hz. Maybe not below 10Hz, but that's better handled by dedicated TR devices anyways.

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I don’t think wanna go under 10, although,with the sealed UMs, I here things in some ULF movies that I never heard before,pretty cool.Find the LaVoce in a store in France,tlhp.I’m in Germany too,can you model the eight Saf for me please, I’m not so good with winISD.Can contact me if you want.

Thanks all alot for your help!

 

 

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