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Are three inexpensive subs better than one expensive sub-Dr. Earl Geddes Approach

post #1 of 2011
2/24/09 at 8:46pm
Thread Starter 
I am a big believer in multiple subs to smooth out bass in something more than a vice like sweet spot. That being said Dr. Earl Geddes has some very interesting ideas of why three inexpensive subs are all that are probably needed in most any room. I am inviting Dr. Geddes to explain his ideas and his reasons why. I would invite questions from both inexperienced and the gurus on subs.
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post #2 of 2011
2/24/09 at 8:53pm
NO. Depends on $$ but ime three $300 subs can't compare to one $900 sub. Maybe three $600 subs will sound good to a $1800 if the room is really large. But I doubt it. The big sub will probally be louder and sound better than all 3
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post #3 of 2011
2/24/09 at 8:58pm
Thread Starter 
Quote:
Originally Posted by Ironmike86 View Post

NO. Depends on $$ but ime three $300 subs can't compare to one $900 sub. Maybe three $600 subs will sound good to a $1800 if the room is really large. But I doubt it. The big sub will probally be louder and sound better than all 3

Exactly what I want to get started. Some opinions and some replys from Dr. Geddes. Hopefully, Todd from Harmon will also participate. Mark Seaton and others, lets get a good debate going (civil please). Full disclosure, I heard Dr. Geddes approach and I have 2 J&L f113's, SVS Ultra 13 and some others. His room was the best I have ever heard.
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post #4 of 2011
2/24/09 at 8:59pm
Quote:


NO. Depends on $$ but ime three $300 subs can't compare to one $900 sub. Maybe three $600 subs will sound good to a $1800 if the room is really large. But I doubt it. The big sub will probally be louder and sound better than all 3

$$$ does not really dictate the performance of a sub. I can pick 3 $300 subs and they would be better then certain $900 subs. Yes, Im talking comercial and not DIY

Heck DIY $600 solution is better then a $1800 comercial solution, so $1800 DIY is just sick but we need not bother with that discussion. The point here is that $$$ is not something we can place as an indicator of performance.

In the end Multiple subs are better then one beast, anyone that has had multiple subs understand how much easier it is to create a better room response. If numbers do thrill people I would take 3-4 subs total cost $3K over one $3K sub...just have to place them/hide them properly to make them seemless to any room I own.
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post #5 of 2011
2/24/09 at 8:59pm
Randy...I have been following the other threads in the speaker and theory sections about Earl's thoughts and your experience with it. I am very interested in experiencing it myself.
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post #6 of 2011
2/24/09 at 9:04pm
Thread Starter 
Quote:
Originally Posted by penngray View Post

$$$ does not really dictate the performance of a sub. I can pick 3 $300 subs and they would be better then certain $900 subs. Yes, Im talking comercial and not DIY

Heck DIY $600 solution is better then a $1800 comercial solution, so $1800 DIY is just sick but we need not bother with that discussion. The point here is that $$$ is not something we can place as an indicator of performance.

In the end Multiple subs are better then one beast, anyone that has had multiple subs understand how much easier it is to create a better room response. If numbers do thrill people I would take 3-4 subs total cost $3K over one $3K sub...just have to place them/hide them properly to make them seemless to any room I own.

Agreed, but the question is "how low can you go" both in $ and depth. That is something that I think will interest a great many people.
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post #7 of 2011
2/24/09 at 9:05pm
Quote:
Originally Posted by penngray View Post

$$$ does not really dictate the performance of a sub. I can pick 3 $300 subs and they would be better then certain $900 subs. Yes, Im talking comercial and not DIY

Heck DIY $600 solution is better then a $1800 comercial solution, so $1800 DIY is just sick but we need not bother with that discussion but the point here is that $$$ is not something we can place as an indicator of performance.

In the end Multiple subs are better then one beast, anyone that has had multiple subs understand how much easier it is to create a better room response.

Yeah but I was thinking more like comparing the subs in the same family for easy comparison. Like 3 Hsu Vtf-1 compared to one Uls15. 3 Svs Pb10 to an Ultra. Same maker to make it fair. My two Pb10 don't sound better than my one Valor in sq or spl. And the two PB10 co$t more. So it's hard to compare different manufactures imo. But maybe in a really large room it may make a difference is you just want or need better responce. In a medium size room @ 3K?? I think one is better. But all rooms are different just my opinion.
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post #8 of 2011
2/24/09 at 9:25pm
Thread Starter 
Quote:
Originally Posted by Ironmike86 View Post

Yeah but I was thinking more like comparing the subs in the same family for easy comparison. Like 3 Hsu Vtf-1 compared to one Uls15. 3 Svs Pb10 to an Ultra. Same maker to make it fair. My two Pb10 don't sound better than my one Valor in sq or spl. And the two PB10 co$t more. So it's hard to compare different manufactures imo. But maybe in a really large room it may make a difference is you just want or need better responce. In a medium size room @ 3K?? I think one is better. But all rooms are different just my opinion.

Just to clarify, Dr. Geddes approach actually encourages different subs. I have invited him to the party, but it is late there in Detroit so we may not hear today. Doesn't stop those interested in posting questions comments and opinions. Thanks to everyone for participating.
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post #9 of 2011
2/24/09 at 9:30pm
Quote:


Yeah but I was thinking more like comparing the subs in the same family for easy comparison. Like 3 Hsu Vtf-1 compared to one Uls15. 3 Svs Pb10 to an Ultra. Same maker to make it fair. My two Pb10 don't sound better than my one Valor in sq or spl. And the two PB10 co$t more. So it's hard to compare different manufactures imo. But maybe in a really large room it may make a difference is you just want or need better responce. In a medium size room @ 3K?? I think one is better. But all rooms are different just my opinion.

Yeah, I think you hit the right points.

In the end every situation has its own solution. I do not know many people that would like to see boxes all over a room, Im talking about people outside of this forum.

One sub is clean and takes up some space, One great sub is better then what most people have already

I suspect the discussion in this thread should be about ultimate sub woofer design. We all have to compromise a little in the real world. Thats coming from a guy that has a IB array in one room and 4 subs in another

Btw, I also have 4 SC-8s in my office unused...these are sweet little passive Velodyne subs that are powered by a SC-1250 (600W per sub)! Im going to set them up and see if they can match even one of my 15" DIY subs.
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post #10 of 2011
2/24/09 at 9:37pm
Thread Starter 
Quote:
Originally Posted by penngray View Post

I suspect the discussion in this thread should be about ultimate sub woofer design. .

I want the discussion to focus on what is needed for the "ultimate" setup and what is a waste of resources. That is Earl's approach. It probably is not for the person who is looking to be able to get to a depth that is more than anything but bragging rights. If people want to discuss rotary subs etc. that may be better in a different thread. I want to discuss real world great bass for both music and home theater im "small rooms". Not stereo bass, not auditorium bass, but bass that everyone would say, "I want that in my set-up" in my home theater for both stereo music as well as 5 or 7 channel movies (concerts). Does that make sense?
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post #11 of 2011
2/24/09 at 9:38pm
Quote:


what is a waste of resources.

Im interested in those points.
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post #12 of 2011
2/25/09 at 12:29am
May I ask what is the subwoofers + mains that Earl is using (that you heard)? Summa?

Is his room acoustically treated in the bass freqs btw? That is impt info.
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post #13 of 2011
2/25/09 at 4:18am
Quote:
Originally Posted by 2100 View Post

May I ask what is the subwoofers + mains that Earl is using (that you heard)? Summa?

Is his room acoustically treated in the bass freqs btw? That is impt info.

Additional questions would be:
What is his main priority, (max output vs. deep extension vs. smooth response, etc.)?
Does he use any EQ, (Audyssey, SMS-1, Behringer, etc.)?
How are the subs integrated for level and phase?
What Bass Management settings is he using?

Links to the "other" threads would be helpful also.

Craig
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post #14 of 2011
2/25/09 at 5:04am
Here is a pretty thorough practical test of 1 vs 2 subwoofers. The findings in this test matches the experience I had with two subs in my own living room, and where I ended up co-locating them.

Even though the test is done with 2 and not 3 subs, it is still a enjoyable read, and a good way to pass some time until the debate gets going

http://www.avforums.com/forums/subwo...large-one.html
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post #15 of 2011
2/25/09 at 5:26am
Two DD-18s or one Gotham.
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post #16 of 2011
2/25/09 at 6:16am
A little late in participating.

First my approach is not about what design of sub to use, I pretty much don;t care. I have not seen a big difference from the design or the maker, its all about the room and the setup. So I will de-emphasize the type and focus on the "how".

In my setup the room is special, its designed to be a listening room and it has extensive LF damping. This is always going to be an advantage. But the approach is the same no mater what kind of room you have. The idea is to use multple subs located around the room to smooth the spatial and spectral response at the seating location. The fact that multiple subs does this has been proven time and time again and really isn't an arguable point. IF you want the smoothest bass, then you must use multiple sources, no single source can compete. The room dominates the LF situation in any audio system and its the sources that must be accomodated to the room.

Sure its not great to have subs all over the place, but you have to get your priorities in order. Do you want the "best" bass or not, because if you do, you better get used to multiple subs. But rememebr that because there are lots of them, they don't have to be extremely large. Mine are about 18 x 16 x 14 for what I call the broad band subs which cover about 50 Hz - 150 Hz. These then overlap the mains, which are simple closed box. I use one Ultra Low Frequency sub that covers 25 Hz - 50 Hz for that lowest octave. At these frequencies only one sub is needed and it matters not at all where it is placed as long as its NOT in the middle of the room (given its size that would never happen.)

The most complicated part of using multiple subs is setup. To get it right you need some measurements to set the parameters on the sub amps correctly. This is done top get as smooth a response as possible. A detailed explaination of this technique can be found at DIY by Markus Mehkau and on his web site.

I am thinking about doing the setup calculations for multiple subs as a service to my customers, but this has to be worked out.

I use no EQ in my setup - although it could use some to improve it. The ideal setup would use something like a Behringer DCX9624, but I haven't bit the bullet and got one yet, because I'm not sure how much benefit it would be in my setup. As Randy has stated its pretty good the way it stands.

Finally all of my subs are very inexpensive, the plate amps about $100 and the B&C woofer about $150 makes up the bulk of the cost if you DIY, but the enclosures are pretty easy to build.

Thats all the time I have for now - later.
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post #17 of 2011
2/25/09 at 6:31am
Quote:
Originally Posted by gedlee View Post

I use no EQ in my setup - although it could use some to improve it.

?

Then how can you recommend your setup?

EQ makes a huge difference as even someone with "golden ears" can point out, it is not humanly possible to hear all of the peaks/nulls/valleys, etc. in the pertinent range.
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post #18 of 2011
2/25/09 at 6:37am
Quote:


its designed to be a listening room and it has extensive LF damping

6" thick bass traps, corner traps? or Big sonotub resonators to attack specific LF?
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post #19 of 2011
2/25/09 at 6:48am
Let me ask this variation, Dr. Geddes; can you envision/describe a room where a single $1400 subwoofer would improve the bass response throughout the listening area more than three $300-$400 subwoofers?

And if there's benefit in using different types of subs, is that benefit lost in buying all three from you (once you start manufacturing them), or from any maker's one model line?
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post #20 of 2011
2/25/09 at 6:56am
Quote:
Originally Posted by gedlee View Post


Sure its not great to have subs all over the place, but you have to get your priorities in order. Do you want the "best" bass or not, because if you do, you better get used to multiple subs. But rememebr that because there are lots of them, they don't have to be extremely large. Mine are about 18 x 16 x 14 for what I call the broad band subs which cover about 50 Hz - 150 Hz. These then overlap the mains, which are simple closed box. I use one Ultra Low Frequency sub that covers 25 Hz - 50 Hz for that lowest octave. At these frequencies only one sub is needed and it matters not at all where it is placed as long as its NOT in the middle of the room (given its size that would never happen.)



An alternative is to use a pair of SPL competent "large" R & L front main speakers that roll off in the 40 to 50 Hz area, then crossover at 50 Hz to the single ULF subwoofer(s) location.




Quote:
Originally Posted by gedlee View Post


The most complicated part of using multiple subs is setup. To get it right you need some measurements to set the parameters on the sub amps correctly. This is done to get as smooth a response as possible. A detailed explaination of this technique can be found at DIY by Markus Mehkau and on his web site.



As you said, you need to take measurements. mark Seaton drove that into my head years ago. You also have to know how to interpret the measurements after you take them. In addition you have to know that measurements can be a bit deceptive, so confirmation of settings is required listening to music and the like.




Quote:
Originally Posted by gedlee View Post


I use no EQ in my setup - although it could use some to improve it. The ideal setup would use something like a Behringer DCX9624, but I haven't bit the bullet and got one yet, because I'm not sure how much benefit it would be in my setup. As Randy has stated its pretty good the way it stands.



The only EQ that is use in my setup is Boundry EQ that is part of my subwoofer's electronics. I have my ULF subwoofer front corner located, and the Boundry EQ does compensate for the FR obtained from that corner location.
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post #21 of 2011
2/25/09 at 6:56am
Quote:
Originally Posted by Johnsteph10 View Post

?

Then how can you recommend your setup?

EQ makes a huge difference as even someone with "golden ears" can point out, it is not humanly possible to hear all of the peaks/nulls/valleys, etc. in the pertinent range.

If you read some of the reviews of his setup, people seemingly very well acquainted with high-end HT are bowled over by what they hear at his place.

As for EQ, when I entered the hobby, because the EQ gear at the time seemed to add a layer of noise (and cost, and separation from the source material), I avoided it myself. For the most part, I've been very lucky with the acoustic characteristics of the rooms my gear has lived in over the years.
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post #22 of 2011
2/25/09 at 7:11am
Quote:
Originally Posted by Johnsteph10 View Post

?

Then how can you recommend your setup?

EQ makes a huge difference as even someone with "golden ears" can point out, it is not humanly possible to hear all of the peaks/nulls/valleys, etc. in the pertinent range.

EQ should be thought of as the exception, not the norm. As Randy points out the bass in my room - WITH NO EQ! - is the best that he's heard. Based on that how can you say that its necessary?
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post #23 of 2011
2/25/09 at 7:17am
Quote:
Originally Posted by J_Palmer_Cass View Post

An alternative is to use a pair of SPL competent "large" R & L front main speakers that roll off in the 40 to 50 Hz area, then crossover at 50 Hz to the single ULF subwoofer(s) location.

I would not consider this an "alternative" at all. The mains have to be located for imaging and other HF "stuff" and cannot be moved or set for the best bass without compromising the rest of the bandwidth. So uncouple the problem by locating the mains where they need to be and don't worry about trying to take them low - this has huge benefits in power handling and cone excursion. Then distribute subs and use their indivudual freedom of settings (gain, LP and phase) to smooth out the response - augmenting the mains if you will. In my system the mains do go down to about 50-60 Hz so they are still active sources at LFs. I just don't try and push them down to the lowest frequencies, let the subs do that.
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post #24 of 2011
2/25/09 at 7:21am
Quote:


As Randy points out the bass in my room - WITH NO EQ! - is the best that he's heard. Based on that how can you say that its necessary?

People posting "Best they heard" without proof is meaningless because of obvious BIAS during the experience.

The only way to confirm if its good is to post the measurements!
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post #25 of 2011
2/25/09 at 7:21am
Quote:
Originally Posted by loopguru View Post

Let me ask this variation, Dr. Geddes; can you envision/describe a room where a single $1400 subwoofer would improve the bass response throughout the listening area more than three $300-$400 subwoofers?

And if there's benefit in using different types of subs, is that benefit lost in buying all three from you (once you start manufacturing them), or from any maker's one model line?

I could never recommend one sub over three no matter what the cost or capability. The problem simply requires a spatial solution and one sub cannot do that.

If I sold three subs for one room, I would slightly stager their tuning. If you bought all the subs from another manufacturer then this wouldn't be easy to accomplish, although it could be done.
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post #26 of 2011
2/25/09 at 7:22am
Quote:


In my system the mains do go down to about 50-60 Hz so they are still active sources at LFs. I just don't try and push them down to the lowest frequencies, let the subs do that.

I 100% agree, I never understood why people are so attached to full range mains....80Hz or higher is great for mains and let a sub system handled the LF properly.

Im a huge fan of multiple subs for this reason....multi-sub placement can solve things even EQs can't.
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post #27 of 2011
2/25/09 at 7:28am
Quote:
Originally Posted by gedlee View Post

A little late in participating.

First my approach is not about what design of sub to use, I pretty much don;t care. I have not seen a big difference from the design or the maker, its all about the room and the setup. So I will de-emphasize the type and focus on the "how".

In my setup the room is special, its designed to be a listening room and it has extensive LF damping. This is always going to be an advantage. But the approach is the same no mater what kind of room you have. The idea is to use multple subs located around the room to smooth the spatial and spectral response at the seating location. The fact that multiple subs does this has been proven time and time again and really isn't an arguable point. IF you want the smoothest bass, then you must use multiple sources, no single source can compete. The room dominates the LF situation in any audio system and its the sources that must be accomodated to the room.

Sure its not great to have subs all over the place, but you have to get your priorities in order. Do you want the "best" bass or not, because if you do, you better get used to multiple subs. But rememebr that because there are lots of them, they don't have to be extremely large. Mine are about 18 x 16 x 14 for what I call the broad band subs which cover about 50 Hz - 150 Hz. These then overlap the mains, which are simple closed box. I use one Ultra Low Frequency sub that covers 25 Hz - 50 Hz for that lowest octave. At these frequencies only one sub is needed and it matters not at all where it is placed as long as its NOT in the middle of the room (given its size that would never happen.)

The most complicated part of using multiple subs is setup. To get it right you need some measurements to set the parameters on the sub amps correctly. This is done top get as smooth a response as possible. A detailed explaination of this technique can be found at DIY by Markus Mehkau and on his web site.

I am thinking about doing the setup calculations for multiple subs as a service to my customers, but this has to be worked out.

I use no EQ in my setup - although it could use some to improve it. The ideal setup would use something like a Behringer DCX9624, but I haven't bit the bullet and got one yet, because I'm not sure how much benefit it would be in my setup. As Randy has stated its pretty good the way it stands.

Finally all of my subs are very inexpensive, the plate amps about $100 and the B&C woofer about $150 makes up the bulk of the cost if you DIY, but the enclosures are pretty easy to build.

Thats all the time I have for now - later.

Dr. Gedess,

Could you provide a link with detailed info for the 3 sub solution?
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post #28 of 2011
2/25/09 at 7:29am
Quote:
Originally Posted by penngray View Post

People posting "Best they heard" without proof is meaningless because of obvious BIAS during the experience.

The only way to confirm if its good is to post the measurements!


This is humorous since I usually rely only on measurements and everyone says -"Its not the measurements that count but what it sounds like!"

First, I had never met any of the people who's reviews are posted on my website prior to their visit, so they came with no "bias", only an open mind. So if there was any bias it could only be because of my charming and magnetic personality which, for those of you who know me, know that's NOT the case.

Second, you are absolutely correct about the measurements and it is my intention to post them. But I simply have not had the time to do this. I think that you will find that they cooborate (SP?) the reviews, which should not be discounted entirely and especially not because they were biased.
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post #29 of 2011
2/25/09 at 7:29am
Thread Starter 
Quote:
Originally Posted by craig john View Post

Links to the "other" threads would be helpful also.

Craig


http://www.mehlau.net/audio/multisub_geddes/

http://www.diyaudio.com/forums/showt...hreadid=134568

I don't think that you should accept anecdotal evidence other than to look at the science behind it. In addition, if you already own more than one (or preferably two) sub, then you can try it and report back. Nice thing is they don't have to be high end.
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post #30 of 2011
2/25/09 at 7:31am
Quote:
Originally Posted by penngray View Post

Im a huge fan of multiple subs for this reason....multi-sub placement can solve things even EQs can't.

This is almost the entire point. EQ CANNOT solve any spatial problem at LF - you fix one point only to make another worse. Only if you solve the spatial problem first, then EQ can be effective. But I have found that once you get the spatil problem solved, the resonse is much smoother and EQ is seldom required.
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