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Multiple Subs


chasec2021

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1 minute ago, derrickdj1 said:

Omnimic is a great tool and easy to learn as another option for taking measurements.  It is more expensive but, one can be up and running in 20 min.  It will take several days for the new user to learn the in's and out's of REW.  The manual is around 90 pages.

I saw that when I was looking at the REW setup process.  I believe the Omnimic kit is around $300?  Either way, I need something better than the RS SPL meter.  I still feel kind of cool when I use it.  How many other folks are even trying that hard.  Patting myself on the back here.

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2 minutes ago, derrickdj1 said:

Omnimic is a great tool and easy to learn as another option for taking measurements.  It is more expensive but, one can be up and running in 20 min.  It will take several days for the new user to learn the in's and out's of REW.  The manual is around 90 pages.

 

Yeah but a simple sweep is a matter of choosing a calibration file, hooking up the wires, and choosing which frequencies to play.  Just not hard at all.  

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3 minutes ago, ACV92 said:

Let us know how you like the mini-DSP.  I've been considering getting one for my baby HT setup in the basement.

 

The normal ones aren't that good for sub use, they clip too easily.  Make sure you get the HD version.  Those should be fine.  I'm switching to Xilica.  

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2 minutes ago, MetropolisLakeOutfitters said:

 

Just doesn't matter with subs nowadays.  Some of the best and highest extending and most accurate midbass drivers are 18's.  Better to match than to try to partake in such things.  It's a solution to a problem that doesn't exist.  

I'm working off of old school thoughts.  I guess I'm not considering the dynamics of current driver/cab design and use. 

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So, riddle me this.  I don't have the room for 18" drivers to run the mid/low mid/upper bass range.  I come to you and say, "I have a UMAX 15 with 3000DSP with a hole around 65hz.  I'm thinking of running an 8" sub high pass at, let's say, 50hz - 55hz, with a low pass of 70hz to fill the void.  I want to run a 1000DSP to the 8".  What would your suggestions be?

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2 hours ago, ACV92 said:

So, I guess my question to everyone is this.  If you could have a choice of 2 scenarios, which would you choose?  Scenario one, two 15's ported/sealed, with two 8's ported/sealed, or scenario two, only two 15's ported/sealed.  To my layman brain, I would choose scenario one.  Why, I could tune the 8's to the upper low end, tune the 15's to pick up where I'm cutting the 8's.  Why, to me, certain size drivers are better suited to perform given tasks.  Hence, why we don't use 4" diameter dome tweets for our highs.  

It is hard to answer with the limited info.  Room size, avr, sub EQ like MCACC Pro, Auddysee, etc. all need to be considered.  For many HT's, there is no need for Mid bass driver if the system can be calibrated.  MBM have become popular over the last year or two.  People employing have lots of sub and may be running into cancellations issues in the midbass.  They are fighting themselves in a respect.

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A given room and gear can only equal so much perfection.  Proper integration of mains and subs=This is the most well-known symbol of the Bahá'í Faith. The 9-pointed star has many meanings, but the most popular of these is the symbol of unity and perfection.  

 

This is an image of perfection and unity.  This should sound good and be slightly different in multiple setups.  Since there is no one perfect time alignment, this represents the best that can be achieved in X room with Y gear and Z correction(EQ and room TX, ect.) with multiple subs.

 

The circle represents the HT and good bass.  The spike are the negative aspect of the calibrations and HT due to being  close to walls, suck outs from door or hallway open, asymmetry  and what ever else in the room that prevents the perfect response.

 

Unless you are in an anechoic chamber or free field with no wind or atmospheric changes, you for the most part are dealing with this diagram.  Even the work by Harman and Geddes has to be taken into  perspective and the room that their findings are based one type of room or a room built for  good acoustical sound.  Horn subs are no exception.   Sound wave physics still applies.   They bring their own deck of cards to the table.  Just decide which deck you would rather play with.  The game is the same, the expertise in setup may not be?

 

This is an excellent topic and not easily answered in a few post and should generate good discussion.  Ask more questions, refute any point that you don't agree with.  This is how we all learn.  Also post some graph for teaching purpose and to be educational.  The subwoofer bassband is something we all can bend to our will with the right knowledge.

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Just a side note, I have never read anything where Geedes said you need identical subwoofers or it can't work.  He has mentioned the the LF sub should match the main.  Setup myths have no place in the scientific approach to settting up multiple subs.

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6 hours ago, ClaudeJ1 said:

I think you missed my point. First I was very happy with that sub, the driver, and it's performance. Primarily, it's  shape just didn't fit the living room, blocking a through way unacceptably. In the basement, the room dimensions changed curves drastically, which was discovered by listening and measurement from my listening position. In the horn mouth it was reasonably flat, but that's not where we listen, right?

 

I'm sure you THTLP is very good also, but you are still talking a single sub, and not TWO, which is what the OP was trying to solve. My response was about that.

 

No worries here either, but in order to disagree with you, I had to show that I had done it successfully. Although, admittedly, my success might have had a little luck thrown in along with good practice and measurement. After all, it's always a SYSTEMS approach, but the ROOM always dominates, no matter how we use to  "shake the air."

 

Sorry Claude i missed this post. If you were able to get your subs to work for you that's great, very happy you are happy. :emotion-21:

 

Why i see the need for multiple subwoofers if you are running a less than stellar model and for home theater due to multiple seating positions i for one am happy where I'm at, I ran multiple subs many times for testing after builds ( up to 6 at a time ) and would never swap them out for the THT or Table Tuba for that matter. Yes i have thought about building another one and where to put it but it was out of boredom when no work was around and not because i was in any way unhappy with the sound.

 

 

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6 hours ago, ACV92 said:

So, riddle me this.  I don't have the room for 18" drivers to run the mid/low mid/upper bass range.  I come to you and say, "I have a UMAX 15 with 3000DSP with a hole around 65hz.  I'm thinking of running an 8" sub high pass at, let's say, 50hz - 55hz, with a low pass of 70hz to fill the void.  I want to run a 1000DSP to the 8".  What would your suggestions be?

 

99.5% chance the issue is not really a problem with the subwoofer itself.

 

Most likely=

Microphone position

Phase

Placement

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4 hours ago, jason str said:

and would never swap them out for the THT or Table Tuba for that matter.

Neither would I. I have never had anything but horn subs either.

However the OP had chosen Direct Radiator subs. So I had to include comments that were more relevant to his cause.

While, under SOME unfortunate circumstances (aren't all rooms unique to each owner?), getting dissimilar subs to work MAY be more difficult, but I think the OP's setup is more typical than ours. IOW, most of the rest of the world uses "subwoofers" that are 8-18" diameter in Bass Reflex boxes, most of them being 8, 10, or 12" cheapos from China bought at Parts Express or that come from Costco or Best Buy (gag me with a fork).

So anyone who can buy, build, or commssion YOU to build a horn sub will STOMP all these "little boxes" that call themselves subwoofers into the ground in terms of performance. People should to to Data-Bass.com to see all the OUTDOOR measurements. The horns, full, or tapped always outperform all the rest, even when they use the same driver.

But I digress....................

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With regards to multiple subs, there is theory and then there is reality.

 

Reality is that it can and will work, if thought out, perfectly.  It's been proven over and over in the real world.

 

In my main HT theater, I have Ultimax 18s in big boxes and Legacy 15s in medium size boxes (4cft is medium now in my world :)) 

They integrate perfectly and seamlessly, with a ruler flat response from 10hz to 100hz, absolutely no phase issues, across the entire couch (8ft across).

 

How I got there -- and how DDJ got his setup where it is, and everybody else who has done this, is through an exceptionally large amount of testing and retesting.  It's a challenge, and one that can be solved.  I will not ever move my 4 subs in the theater ever, unless I move or need to change the setup for some reason.  It's that good at this point imo.  

 

CEC (moderator here) imo is perhaps the most astute I've come across here regarding multiple subs.  It's as he has said -- more complicated, and has the possibility of creating a worse setup, if done incorrectly.  But when it is right, it's the BOMB!  

 

Changing the sub positions and delays is a seemingly endless process but one if followed that leads to Nirvana :)

Measurement is beyond critical to do this...and I agree with many above, REW at it's most basic level is actually plug and play.  I took measurements within 10 minutes of setup and was able to use the basic functions decently within an hour or two.  Over a period of weeks and lots of measurements and reading, I have learned what most of REW does, each tab another exploration down the rabbit hole of acoustics....

 

This is an 8 foot couch, 5 measurements across the ear level listening position, and then 3 more towards the front of the couch one in each seat.  The same positions I use when running Audyssey.   These 4 subs require ZERO PEQ, only Audyssey runs to bump up one small broad dip in the lower bass area.  It can be done!  

 

5925c2dadc2a8_Subs8positionusedinAudysseyfullcouch.jpg.41109d66af4ecde9f2ffea821bc93fa5.jpg

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That is an excellent graph Rob.  People need to post graphs because a picture is worth 1000 words.  It also show what is possible.  Your point on Theory and our small HT is right on target.  There are so many people using multiple subs now and employing NF sub.  This sets up a scenario where the NF subs and far field sub in the room are most likely not identical due to room and space restrictions..

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16 minutes ago, derrickdj1 said:

That is an excellent graph Rob.  People need to post graphs because a picture is worth 1000 words.  It also show what is possible.  Your point on Theory and our small HT is right on target.  There are so many people using multiple subs now and employing NF sub.  This sets up a scenario where the NF subs and far field sub in the room are most likely not identical due to room and space restrictions..

 

A picture may tell 1000 words but it does not tell the whole story, my door is always open for skeptics.

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2 hours ago, derrickdj1 said:

That is an excellent graph Rob.  People need to post graphs because a picture is worth 1000 words.  It also show what is possible.  Your point on Theory and our small HT is right on target.  There are so many people using multiple subs now and employing NF sub.  This sets up a scenario where the NF subs and far field sub in the room are most likely not identical due to room and space restrictions..

Someone mentioned earlier in this thread or another one that they liked your sub graph, that it better supported the arguments going back and forth with data.

 

Geddes did in fact suggest that a HT enthusiast try putting their largest subwoofer in a corner, almost inevitably a front corner, and then use one or more additional subs (I seem to recall him using 3 in his case-study) to fill in where there are issues within the room.  In suggesting that he is in fact saying that having different subs is not only practical but usually relatively straight-forward to integrate.   

 

Sometimes the "rules" or best practices can become mantras that get in the way of having a deeper understanding of a concept (imo).  It may be a best practice to only use all vented subs, or sealed subs, it may be a best practice to use all identical subs, it may be a best practice to put them in a certain place in a room.  But none of those best practices are anything more than guidelines.  They provide insightful shortcuts and ideals.

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On 5/24/2017 at 4:33 PM, RoboKlipsch said:

Geddes did in fact suggest that a HT enthusiast try putting their largest subwoofer in a corner, almost inevitably a front corner, and then use one or more additional subs (I seem to recall him using 3 in his case-study) to fill in where there are issues within the room.

 

 In suggesting that he is in fact saying that having different subs is not only practical but usually relatively straight-forward to integrate.   

Mr. Geddes suggested putting the largest sub in a front corner?  :o

 

Mr. Geddes obviously never had Khorns.  B)

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