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Multiple Subs


chasec2021

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Hey guys, I have a question I wanted to get y'alls opinion on. I have read on here that people would rather have 2 lesser subs than run one higher end sub (or at least that's how I read it). I currently have a newly put together (since Christmas) set up that features the Ref ii line for all of my speakers, with the only exception being the subwoofer. It is a BIC Accoustec (which was a huge upgrade from the yamaha sub I had gotten a decade ago from Best Buy) and was wondering what you guys thought the benefit would be if I were to get a second subwoofer. At the moment, I am running a receiver that has 1 sub out, which will in the long run be switched out for a receiver that is more of today's technology to have atmos, multiple subs, and things of that nature down the road.

 

So here is my question, should I decide to get a second sub to run in this system, should I get a duplicate of the same sub, or should I think about going a different sub to try to hit all the base notes by getting a different sub to run with the current one. Should I go a different route, is there a good Klipsch sub that would be a good compliment to what I am doing? Nothing pressing about this question, but eventually I will want sub number 2 to add to the setup and wouldn't mind having that plan in place when the time comes

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17 minutes ago, CECAA850 said:

2 similar subs are much easier to integrate than dissimilar ones. It can be done but it's a lot more work.

So, getting another of the same that I have would probably be the best route then? or the easier route. I don't have a problem putting in the time and effort to integrate a different sub if there would be benefits to getting all the bass notes. Not all subs sound the same, and I don't have a problem trying to hit all the notes through this process, even if it is time consuming.

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Since two different subwoofers are going to have different frequency response and all that I just can't imagine it being totally smooth, especially when you consider that one sub may be tighter or faster than the other, or have greater musicality or dynamics. I haven't personally tested running two different subs at the same time, but I can imagine all sorts of unpredictability coming out of that many differing characteristics. I imagine it will also take away from hearing the improved quality of whichever sub you get next.

 

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I have had a mixed system of different subs for a long time and they can play well together.  Certain things should be done.  Get subs with similar output capabilities and frequency response.  With good quality subs the tighter, faster and or more musical sub is most a mute point. For the most part, the bass notes are so long in the small HT, they are all mutually coupled.  Most AVR's with 2 sub outputs have an internal Y connector.  Here is a good read on setting up 2 subs. :http://forum.blu-ray.com/showthread.php?t=95817

 

A good smooth response is possible using different subs.  I have 5 different subs varying in size from 6 cu ft to 17 cu ft.  Here is a pic of a recent house curve.

 

 

4.30.2017 House curve 4.png

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A few things on the graph.  It is not a straight line intentionally.  This is an aggressive house that is higher in the low frequencies.  I have a vented sub system.  So, the tappering of the low end near 20 Hz is the hpf at 16 Hz.  This is to protect the driver.  The XO in the avr is 80 or 100 Hz, I can't remember.  

 

This particular house curve will allow Reference level playback, speakers hitting 105 db max and subs hitting 115 db.  plus redirected bass.  The system will get a workout in a couple of hour.  Underworld-Blood Wars tonight!:)

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You always want several of the most capable subs you can afford.  I often recommend 2 lesser subs to folks wanting to stay in a budget. 

More subwoofers will have more cone area and thus will generate XX dB with less cone motion (and stress) each.  That will generate less distortion. 

 

Having had 1, then 2, and now 4 of the same subs, I can heartily recommend multiple subs.  By being in different places they will not all excite a single room mode and you will get more even bass response throughout the room, in addition to prodigious output! 

 

You can always turn the throttle back, but you can't turn it up, if you're already max'ed out. 

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I am in the camp of one quality sub vs two lessor subs.

 

In my living room I am running 3.2, Khorns L/R, a Klipsch RW-12d (ported) in the middle and a DIY 15" (sealed) right, near the side.

 

I have not tried to dial them in, I just went by ear.  I wanted the 15" sub on the right because in an orchestra that's where the low brass sits, baris, trombones and tubas.  I haven't heard any particular improvement by using two subs.

 

I am still in mix'n'match mode so I know there is some performance being left on the table.

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14 hours ago, wvu80 said:

I am in the camp of one quality sub vs two lessor subs.

 

In my living room I am running 3.2, Khorns L/R, a Klipsch RW-12d (ported) in the middle and a DIY 15" (sealed) right, near the side.

 

I have not tried to dial them in, I just went by ear.  I wanted the 15" sub on the right because in an orchestra that's where the low brass sits, baris, trombones and tubas.  I haven't heard any particular improvement by using two subs.

 

I am still in mix'n'match mode so I know there is some performance being left on the table.

 

If you sit on one place all the time multiple subs don't help unless you need more volume, then you can stack them for more volume.

 

Mixing subs can do more harm than good due to phase cancellation.

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Agree @jason str.  My subs have not been set up properly and it is very likely they are canceling each other out.  They do sound good as is especially with movies, but I consider movies very low level demand for sub work.  The DIY Reference 15 sounds great with music, the dual sub thing was just for kicks.

 

If I decide to run dual subs I will likely build a second Reference 15 and position them correctly.

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1 hour ago, jason str said:

 

If you sit on one place all the time multiple subs don't help unless you need more volume, then you can stack them for more volume.

 

Mixing subs can do more harm than good due to phase cancellation.

Jason, I don't agree with the mixing subs comment. Neither does Dr. Earl Geddes. He uses 3 that are in different place in the room with different bands and different EQ.

I use two different subs with slighly different bandwitths for a more "musical" blend (I had 4 in my other place, now only use two of the 4). BUT, you have to be able to measure them. The ideal is FIRST, the PLACEMENT, then SECOND, the EQ. Horn subs are best because of their higher efficiency and output, can withstand far more EQ if necessary, with far more headroom and less power amplification.

 

THE very best reference for this is Todd Welti's research paper from JBL. 

 

#1) 4 subs in wall centers is best for the smoothest bass requiring the least EQ

#2) 2 subs Front and Rear in wall centers (almost as good as #1)

#3) 4 subs in corners (less smooth but higher output)

 

Look up Geddes and the attached Welti PDF for the best answers. GET REW and a UMIK to verify.

 

My own setup is #2 with an OThorn sub that is 25-100 Hz. and a Danley TH-50 that is 18-70 Hz. My bass at the sweet spot, blending to my R and L channels, is ruler flat from 18-200 Hz.

 

Your "mileage" will DEFINITELY vary.

multsubs.pdf

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On 5/21/2017 at 4:20 PM, derrickdj1 said:

A good smooth response is possible using different subs.  I have 5 different subs varying in size from 6 cu ft to 17 cu ft.  Here is a pic of a recent house curve.

I agree with this comment about different subs helping to solve the MODAL signal domination of rooms in the bass range.

 

I'm glad you are supplying real DATA to support your comments, unlike others here who merely supply opinions with no data to support it.

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1 hour ago, ClaudeJ1 said:

Jason, I don't agree with the mixing subs comment. Neither does Dr. Earl Geddes. He uses 3 that are in different place in the room with different bands and different EQ.

I use two different subs with slighly different bandwitths for a more "musical" blend (I had 4 in my other place, now only use two of the 4). BUT, you have to be able to measure them. The ideal is FIRST, the PLACEMENT, then SECOND, the EQ. Horn subs are best because of their higher efficiency and output, can withstand far more EQ if necessary, with far more headroom and less power amplification.

 

THE very best reference for this is Todd Welti's research paper from JBL. 

 

#1) 4 subs in wall centers is best for the smoothest bass requiring the least EQ

#2) 2 subs Front and Rear in wall centers (almost as good as #1)

#3) 4 subs in corners (less smooth but higher output)

 

Look up Geddes and the attached Welti PDF for the best answers. GET REW and a UMIK to verify.

 

My own setup is #2 with an OThorn sub that is 25-100 Hz. and a Danley TH-50 that is 18-70 Hz. My bass at the sweet spot, blending to my R and L channels, is ruler flat from 18-200 Hz.

 

Your "mileage" will DEFINITELY vary.

multsubs.pdf

 

What part do you not agree with Claude ?

 

My comment was based on mixing different subwoofers can not will cause more harm than good as in not taking the time to set up correctly.

 

I had a long discussion with Bill Fitzmaurice about mixing different horns of different lengths in the same passband and was told it was a bad idea.

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59 minutes ago, jason str said:

 

What part do you not agree with Claude ?

 

My comment was based on mixing different subwoofers can not will cause more harm than good as in not taking the time to set up correctly.

 

I had a long discussion with Bill Fitzmaurice about mixing different horns of different lengths in the same passband and was told it was a bad idea.

While I have a lot of respect for Bill Fitzmaurice and his horn designs, he has never published peer reviewed papers in the AES on the subject.

The "idealized" behavior of his horn curves are just that. The measurement I got from the unit I bought from you years ago bears this out when the horn behaved RADICALLY different in different rooms and listener positions.

 

So, having SUCCESSFULLY created the flattest bass I've ever had in my life from 18-200 Hz. using the bottom end of Danley Synergy Horns coupled to two different Tapped Horn subs that use 2 different horn lengths, different drivers, resulting in two different bands that you can clearly discern when doing room correction test tones. The only thing these two cabinets have in common is the PRINCIPLE of tapped horns, which have peaks and dips in different spots according to their designers, who I have also communicated with. I have also successfully integrated two IDENTICAL subwoofers (Front and Rear Wall Centers), and non-identical subs in different assymetrical room positions.

 

While I admit that, perhaps, having identical subs do make SOME things easier, it doesn't negate the FACT that assymetrical subs and assymetrical room positions ALL with minimal EQ, can provide a workable solution. The proof is in the pudding, so to speak.

 

Based on my own measurements, CLEARLY, room MODES dominate the resultant bass and are never flat. This concurs withe Todd Welti studies, which were made easier for HIM by using identical subwoofers for his experiments. But once his conclusions were reached about IDEAL "top 3" configurations, having different subs with different bands were not mentioned but proven to work by Dr. Earl Geddes, which gave me the idea that it could work and, indeed, did work very well in two different places.

 

I do think, though that things get more difficult if you mix direct radiator subs with horn subs, but I think subs that work on the same FAMILY of principles can have different sizes and bandwithds, profivided they are still optimized via POSITION.

 

In God we trust, all others provide data, so I shall practice what I preach.

 

Below you will find a 1/48th octave resolution RTA measurement from my sweet spot. The OThorn in front and the Danley TH-50 (both tapped horns) are exactly the same distance from the microphone, which is what the REW RoomSim told me was the best place for my head and the resultant microphone placement. This is Right and Left channels, and both subs on (2.2). The subs are configured in mono so they get the same signal. However, they are individually EQ'd a little differently to suit their particular behavior in their respective room positions.

 

 

sh50_2.2rtanatural.jpg

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The THT i sold you had a budget driver installed as mentioned before sale, the frequency response may have differed from published graphs, i never had a chance to measure it. The driver was approved by Bill so i went with it.

 

My current THTLP is near flat from 18 - 85 Hz where it falls off quickly on both ends but works perfect with the La Scala's. A bit of EQ on the sub and some on the La Scala bass bin made a world of difference.

 

I'm not going to provide any graphs, take my word or don't as its no worry of mine.

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Here's my uneducated view, in my living room, before my wife made me move all my wares, I had an SVS 20-39 PCI ported cylinder in the front right corner of the room, and my little SW-10 active 10/12 passive right behind the couch, directly in the middle.  In my situation, I used the SW-10 to bring in more of the upper register as the 20-39 didn't have great response in the upper bass frequencies, to my ears anyway.  The near field of the SW-10 gave the music more of the punch and the 20-39 flaunted the lower register.  I blended crossover points by ear, tried phase, to no avail, but the darn setup rocked pretty hard, sounded good to me.  I'm sure if I had a mic/software, or have heard systems like you guys have, I may have a different opinion.  My point being, I don't see the negative in using different subs, as long as they're tuned right.

 

I just recently finished my single UMAX 15, and I'm still trying to get the sound right.  It's a 2.1 setup now, and I'm already considering a second one.  I only have an SPL meter now and found a big drop between 62.5 and 70 hz, at or more than 10 db considering bands on either side.  I'm messing with the INuke software to try and level that drop but am still learning about Q effects, filters, room modes, etc.  Anyway, if I had the budget I would probably try an HO 12, 10, or even an 8, to boost that hole and blend it with the UMAX 15.  I don't see where using different subs to achieve different bandwidths is a negative.  It's all in the setup, and ultimately boils down to the listener.

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