2 Different Subs With Complementary Purposes?

[JiminSTL]

Have been persuaded by the many knowledgeable sources on this Forum that I need 2 subs, given the cubic footage of my listening area.

 

My questions: 

1.       Do I want two subs identical/very close in their technical specs as possible? 

2.       Or, are there any thoughts and opinions about having one sub primarily for very low—primarily HT applications--sub frequencies (18Hz to ??? Hz), and the second sub primarily for a mid-bass range (???Hz to ???Hz)?

3.       Do my fronts (KLF-30s)—going down to 36Hz, my center (KLF-C7), and my surrounds (KLF-20s) going to 34Hz make a difference?  I really would like to/think that I should maximize their 12” and 10” speakers as much as possible.

 

But, rather than attempting to answer my own questions, I really welcome the input of those with more experience.

 

FYI, I am comfortable with some sort of DIY with flat packs or something along those lines, too.

[Paducah Home Theater]

We've talked about #3 elsewhere, it is your own opinion really, you'll have to play with the crossovers once it is set up.  THX is the opposite idea as yours but some guys like their mains to carry more of a load.  The only remotely correct answer is that THX recommends crossing over everything at 80hz.  My experiences confirm that this does sound best for voices plus you can run your speakers harder.  However I like concert movies to be crossed over lower.  

[Coytee]

Technically I don't know your answer.

 

From a seat in the pants point of view, I would (like) to think that although two identical subs are best, that you might be able to mix/match.  This is what I base it on:

 

When I was in college (and that general era of my life), I had a pair of LaScalas and a pair of Electrovoice Interface D's.  I had them both hooked up in the same system.

 

The LaScalas would punch you in the chest but were low on deep bass.  The EV's had a -3db point of 28Hz @ 106 db (if I recall the specs correctly)

 

Either speaker sounded fine & dandy on its own but together, the EV's shook the house (and never felt as though they were punching you in the chest) and the LaScalas punched you in the chest but could never shake the house.  Combined, you had a cacophony of violence that punched & shook & vibrated everything.

 

Was it the highest of pure fidelity?  Nope but when you are in college, you don't always have the best setup available to you.

[willland]

1.       Do I want two subs identical/very close in their technical specs as possible? 

 

There are many advantages to that but it is not necessary for them to be "identical".  It helps for them to share similar tonal characteristics and power.

 

 

 

2.       Or, are there any thoughts and opinions about having one sub primarily for very low—primarily HT applications--sub frequencies (18Hz to ??? Hz), and the second sub primarily for a mid-bass range (???Hz to ???Hz)?

 

When I first got my Revel B15, I ran it and my RSW-10d in that manner.   With the RSW-10d not capable of significant sub 25Hz impact, I utilized it's midbass punch prowess.  I let the B15 handle the lower bass region with it coming in to play at 40Hz on down.  It was a great configuration for music and only marginally good for HT.  The HT shortcomings were not due to the B15/RSW-10d lack of quality, but a matter of room size. Just not enough oooomph for my 6000ft3 room.  That all changed when the SVS SB13 Plus came to the party.    When the RT-10d twins crashed the party, my setup was complete.

 

 

 

3.       Do my fronts (KLF-30s)—going down to 36Hz, my center (KLF-C7), and my surrounds (KLF-20s) going to 34Hz make a difference?  I really would like to/think that I should maximize their 12” and 10” speakers as much as possible.

 

With such large main speakers drivers, then maybe they should be utilized more and get a pair of larger subs to handle the low stuff.

 

Bill 

Edited May 10, 2015 by willland

[JiminSTL]

Hmmm, Willand.  Obviously, you have given your layout, specs, and equipment a lot of thought.

 

Am wondering--now, don't laugh--if I might get by with one 15" or 18" DIY PLUS the Klipsch LF-10 sub?  The LF-10 has the following specs shown below.

 

The fact is that I would prefer to NOT have to buy/build a 2nd sub.  On the other hand, if I must, I will.  No point in doing a half-***** job and not having things be right!

 

P.S.  Have no idea what that 1/8 space below is . . . .

 

FREQUENCY RESPONSE:

19Hz-100Hz(+-)3dB

MAXIMUM ACOUSTIC OUTPUT:

120dB SPL @ 1/8 space, 1 meter

MAX ACOUSTIC OUTPUT:

120dB SPL @ 1/8 space, 1 meter

AMPLIFIER:

BASH® digital hybrid

SUBWOOFER:

K-1073-K 10" (25.4cm) Kevlar / Fiber-composite cone / cast aluminum frame active / Two KD-104-K 10" (25.4cm) Kevlar / Fiber-composite cone passive radiators

LOW PASS CROSSOVER:

Continuously variable from 40-120Hz, 36dB/octave slope above 120Hz

ENCLOSURE MATERIAL:

Medium density fiberboard construction (MDF)

ENCLOSURE TYPE:

Bass reflex via dual passive radiators

[willland]

Hmmm, Willand.  Obviously, you have given your layout, specs, and equipment a lot of thought.

 

Just as little.  

 

Am wondering--now, don't laugh--if I might get by with one 15" or 18" DIY PLUS the Klipsch LF-10 sub?

 

I am sure a DIY 15 or 18 would be awesome but I really don't have a clue about the LF-10.

 

Bill 

[twistedcrankcammer]

Hi JiminSTL!

 

I run 4 subs with a total of six 18 inch drivers. Like you are suggesting, I run two KPT-684s as musical subs for output down to 35Hz and two Velodyne HGS-18IIs for movie content down to 15Hz.

 

If it were me, as I did, I would buy two low frequency monsters first, before I would mix the set. I do however enjoy the KPT-684s very much on music.

 

Mustang guy runs a similar 4 sub setup with two KPT-684s and two Danley Lab  Horn subs for the Low content.  Mustang guy believes that his Danleys play much Louder, however with the KPT-684s having a max acoustic output of 130Db, I suspect he thinks this because of how much content you don't hear with the KPT-684s because they do only go down to 35Hz. He is also filling many more cubic feet with sound than I.

 

Perhaps Mustang guy will also weigh in with his own thoughts on this matter.

 

Roger

[CECAA850]

Dissimilar subs obviously work but similar subs are easier to calibrate IMHO. 

[JiminSTL]

Like your thoughts.  Keep 'em coming!

[Scrappydue]

Hmmm, Willand. Obviously, you have given your layout, specs, and equipment a lot of thought.

Am wondering--now, don't laugh--if I might get by with one 15" or 18" DIY PLUS the Klipsch LF-10 sub? The LF-10 has the following specs shown below.

The fact is that I would prefer to NOT have to buy/build a 2nd sub. On the other hand, if I must, I will. No point in doing a half-***** job and not having things be right!

P.S. Have no idea what that 1/8 space below is . . . .

FREQUENCY RESPONSE:

19Hz-100Hz(+-)3dB

MAXIMUM ACOUSTIC OUTPUT:

120dB SPL @ 1/8 space, 1 meter

MAX ACOUSTIC OUTPUT:

120dB SPL @ 1/8 space, 1 meter

AMPLIFIER:

BASH® digital hybrid

SUBWOOFER:

K-1073-K 10" (25.4cm) Kevlar / Fiber-composite cone / cast aluminum frame active / Two KD-104-K 10" (25.4cm) Kevlar / Fiber-composite cone passive radiators

LOW PASS CROSSOVER:

Continuously variable from 40-120Hz, 36dB/octave slope above 120Hz

ENCLOSURE MATERIAL:

Medium density fiberboard construction (MDF)

ENCLOSURE TYPE:

Bass reflex via dual passive radiators

sorry I'm on my phone so I can't highlight just a few words. To me you just said yourself! Don't halfa$$ anything. Build two similar subs and call it a day. Buy once cry once. You will be happier in the end and won't have that ohhh man I wish I would have done this feeling.

[mustang guy]

I don't have Danleys. I have two B Fitzmaurice THT's and two KPT-684's. Currently I am only running the THT's, but I am on the verge of implementing a 4 sub setup. 

 

Mind you, my space is 78,000 cu ft. My experiment will be to have the KPT-684's on the side walls half way back and facing eachother. The THT's will be on the front and back walls, also mid-room and facing eachother. The phase will be set at zero. This should give the most even distribution of bass throughout the room.

 

The THT's are non-existent below 22Hz. The KPT-684's are eq-able flat to 25Hz. Not much difference there. THT's are single 15" horn loaded, and the 684's are reflex port tuned dually 18's.

 

In such a large room, I don't want to go much below about 30Hz anyway. Movie houses are pretty much the same. A couple KPT-684's is all they would have in a theater with 250 seats, for instance, and no eq on the sub.

Edited November 5, 2014 by mustang guy

[Paducah Home Theater]

Personally I don't know why you're still messing around with that little 10, just sell it or stick it in a bedroom, it's just taking up space.  Trying to incorporate it is more trouble than its worth, you're not really gaining anything by trying to squeeze one 10" sub in the mix.  

 

Are you using it now?  I haven't heard you say this.  If not, hook the thing up and see if it will even remotely do what you want it to.

 

2.       Or, are there any thoughts and opinions about having one sub primarily for very low—primarily HT applications--sub frequencies (18Hz to ??? Hz), and the second sub primarily for a mid-bass range (???Hz to ???Hz)?

3.       Do my fronts (KLF-30s)—going down to 36Hz, my center (KLF-C7), and my surrounds (KLF-20s) going to 34Hz make a difference?  I really would like to/think that I should maximize their 12” and 10” speakers as much as possible.

If you want midbass, you already have several 10's and 12's and 8's all around you.

Edited November 5, 2014 by MetropolisLakeOutfitters

[Don Richard]

It's difficult enough to integrate 2 similar subs into  a system. Different subs would be harder to get right, even with help from a DSP.

[CECAA850]

It's difficult enough to integrate 2 similar subs into  a system. Different subs would be harder to get right, even with help from a DSP.

 

 

x2

[willland]

It's difficult enough to integrate 2 similar subs into  a system. Different subs would be harder to get right, even with help from a DSP.

 

Not really hard, just time consuming.

 

Lot's of trial and error.

 

Bill

[CECAA850]

A question then with hypothetical dissimilar subs.

 

Using a receivers crossover, we won't worry about the top end as both subs will be cut off at the same frequency.

 

Sub A is flat + - 3dB to 25 Hz.

Sub B is flat + - 3dB to 20 Hz.

 

Both subs are calibrated at the listening position.  How do you account for the 6 to 10dB loss at the frequencies between 20 and 25Hz?

[willland]

Both subs are calibrated at the listening position. How do you account for the 6 to 10dB loss at the frequencies between 20 and 25Hz?

 

In my case, both the SVS SB13 Plus and the Revel B15 test about the same with pretty even output.  The corner loaded RT-10d's drop off pretty rapidly below 25Hz but the other two easily handle the gap.

With just two subs, it may be more of a challenge in your scenario.

 

Bill

[derrickdj1]

I also do not think it is hard to integrate non-identical subs.  It just takes time.  It is easier if the subs have similar power handling capabilities, FR, and tonal qualities.  I have used identical and non-identical subs with success.  First, you have to decide on what you want out of the bass system in the HT/music.  Room volume plays a big part in what you need to get the job done.

 

I would sell the small sub.  An 80 Hz XO is fine even with large speakers.  It will provide better power management of the system.  I have not read one scientific paper that said trying to XO large tower lower is superior to letting the subs do their job.  I have no problem XO my system at 80 Hz. Getting the bass right in a system is the hardest thing to accomplish and may cost some money to do it right.

 

The answer to the question on what if there is a 10 db difference when mixing subs, don't worry to much about it.  It is usually in the lower register where one sub is stronger and bass is omnidirectional.  These frequencies are usually around or below 20 Hz and are not audible.  In this situation with the two subs, it is the best that can be accomplished with that setup.  The biggest thing is integrating them to work together over their given FR.   Also, if using a much smaller sub, place it close to the MLP and level match the subs.

 

The one point that is not up to argument is that multiple subs lead to the best FR in the room and is supported by E. Geddes and the Harmon papers.

Edited November 6, 2014 by derrickdj1

[Heritage_Head]

 

1.       Do I want two subs identical/very close in their technical specs as possible? 

 

There are many advantages to that but it is not necessary for them to be "identical".  It helps for them to share similar tonal characteristics and power.

 

 

 

2.       Or, are there any thoughts and opinions about having one sub primarily for very low—primarily HT applications--sub frequencies (18Hz to ??? Hz), and the second sub primarily for a mid-bass range (???Hz to ???Hz)?

 

When I first got my Revel B15, I ran it and my RSW-10d in that manner.   With the RSW-10d not capable of significant sub 25Hz impact, I utilized it's midbass punch prowess.  I let the B15 handle the lower bass region with it coming in to play at 40Hz on down.  It was a great configuration for music and only marginally good for HT.  The HT shortcomings were not due to the B15/RSW-10d lack of quality, but a matter if room size. Just not enough oooomph for my 6000ft3 room.  That all changed when the SVS SB13 Plus came to the party.    When the RT-10d twins crashed the party, my setup was complete.

 

 

 

3.       Do my fronts (KLF-30s)—going down to 36Hz, my center (KLF-C7), and my surrounds (KLF-20s) going to 34Hz make a difference?  I really would like to/think that I should maximize their 12” and 10” speakers as much as possible.

 

With such large main speakers drivers, then maybe they should be utilized more and get a pair of larger subs to handle the low stuff.

 

Bill 

 

Great looking room bill. Have you considered putting some panels up? I bet you would hear an upgrade. 

[Heritage_Head]

Personally I don't know why you're still messing around with that little 10, just sell it or stick it in a bedroom, it's just taking up space.  Trying to incorporate it is more trouble than its worth, you're not really gaining anything by trying to squeeze one 10" sub in the mix.  

 

Are you using it now?  I haven't heard you say this.  If not, hook the thing up and see if it will even remotely do what you want it to.

 

2.       Or, are there any thoughts and opinions about having one sub primarily for very low—primarily HT applications--sub frequencies (18Hz to ??? Hz), and the second sub primarily for a mid-bass range (???Hz to ???Hz)?

3.       Do my fronts (KLF-30s)—going down to 36Hz, my center (KLF-C7), and my surrounds (KLF-20s) going to 34Hz make a difference?  I really would like to/think that I should maximize their 12” and 10” speakers as much as possible.

If you want midbass, you already have several 10's and 12's and 8's all around you.

 

I agree. The 10" will hold you back and make everything harder than it needs to be. But if you can get it near field. I mean like right next to the lp. Then a 10" could hang with a bigger sub thats placed on the other side of the room.