Geddes multiple subwoofer method - 3 subs vice 4


Geddes recommends 3 subs for optimal sound - a different perspective

 

Interesting video depicting Geddes philosophy on using subs. Also, he treats the main speakers as part of the bass solution and does not recommend using high pass filters as this takes away from the total bass capabilities of the entire speaker sub interface system. I am going to experiment this weekend. Also, a higher crossover frequency for the first sub collocated closer to the main speakers is new to me. Recommended above 100 hertz for the first sub and then incrementally lower for the 2nd and 3rd sub in an asymmetric pattern. 
 

I feel like the Geddes approach for sub integration closely resembles what I have been doing for years without even knowing this method. So, my 18” deep bass and 15” mid bass drivers on the field coil speakers become part of the solution instead of being taken out of the equation. That’s what I have been doing and that’s what I thought sounded best to me. Multiple ways to do sub integration but this method is the one that pretty mirrors how I have been doing it for years.

audioquest4life

Dear @deep_333 : My room geometry is not easy to use the Harman calculator, these are more or less the dimensions/shapes:

as I posted my apartment has 2 parlors from the entrance door. First parlor where is not seated the system its wall distance to the other extreme, where is the second parlor/listening area/system, are 9.70m to the window that’s behind the speakers.

Now the speakers are at 95cm. in front of the windows and the left speaker is at 30cm. from the side wall, the rigth wall is at 8.5m from the left one.

The center of the speaker tweeters in between are at 2.60m and the speaker woofers at 3.05m.

Listening area length is 4.70m and the wide is around 4.5m. Exist a passageway of 1m. wide by 14+m. in length. This apartment has 3 bedrooms and two complete bathrooms. All in one floor, so is a little big.

Dining room is big and the dining room central/rectangular table is for 10 seated people.

Both parlors are full of ( mainly ) wood furniture as the dining room and all around exist wood display cabinet ( like seven of them ). The parlor furniture are made from natural absorbtion materials and due to the shape of the wood furniture it works as difussors.

Rigth now the system is working truly fine and till today I think that I can’t do ( ? ) anything to improve its very high quality MUSIC reproduction and very high resolution.

It does not matters the SPLs the room/system just refuse to distort: MUSIC stage always is there/nothing change but SPL. Yes, its noise floor and distortions levels are so low that can be dangerous to the ears with out taking in count due that we can’t be aware of those distortion levels. No, I normally listen at around 82 or even a little lower db SPL and only during some kind of system audio items tests I listen at 95db with peacks at 105+db for only a few minutes.

 

R.

@rauliruegas wrote:

In general I like the immediacy of the MUSIC reproduced sound that’s a main live MUSIC characteristic.

+1

One " but " on horns ( at least to me ) is that I don’t like its reproduced sound seated at near field position ( say 2m. ) I think we need at least no less than 3m. and obviously that depends of the room too.

It depends on the particular horns (and amps) too. Auditioning the popular JBL 4367 monitors (which are somewhat smaller than my mains + subs system) I’ve found them too "hot" sounding over longer durations in being more forward and incisive in their sonic nature than my own system. To by fair, in many ways the 4367’s are delightful speakers; exhilarating, energetic, honest, clean, extremely informative (I’d say a wee bit too "insisting") and - apart from the low octave shifting towards a warmer imprinting - fairly coherent.

The thing is though, to my ears and sensibilities they simply become too much over time, and moreover I find string instruments like violins to have a slightly "plastic"-like and/or nasal character to them (I prefer the M2’s and 4349’s here with their flatter waveguide), which is a dealbreaker to me. My EV main speakers by comparison with their large format horns + subs are sonically more akin to large panel speakers; more relaxed, less "beamy," fuller and more visceral/physical/dense. Where it becomes apparent they’re a larger package overall, apart from their more natural height of presentation, is at higher SPL’s (not least with movies) where the sheer unadulterated force and power is at full display.

It’s what I’ve been saying quite a few times by now: typically, the larger the horn the less it sounds like a horn. Somehow though it goes contrary to what people expect of smaller vs. larger horns in thinking the latter will be too much for its own good in domestic environments (and they may be in smaller spaces), but often it’s the other way ’round and smaller horns sounding more agitated and "aimed" at the listener. Visitors, upon listening to my setup, have often been surprised at the presentation and that it isn’t intrusive or in-your-face. There’s no way around though that horns are more present and in a way more direct sounding with less reflected sound being part of what hits the ears.

At near field position my ADS are way better than horns or electrostatics.

I would expect that too. I’m sitting about 11ft. from my mains, and here they cohere and sum very well. The TH subs, flanking the mains in the corners, are carefully dialed in delay-wise through the Xilica DSP.

Unfortunatelly I never had the opportunity to listen a true horn subwoofer ( at least that goes to 16hz. ) but I tend to beleive you.

It’s an experience that’s difficult to explain. Those who’ve heard horn subs often find them to sound more convincingly extended than smaller direct radiating subs, even though the latter may extend deeper on paper. For horns to go below 20Hz very large size is required. Mine roll off below 25Hz, and below 20Hz there’s no information whatsoever - both due to the specific design limitations and that they’re high-passed below 20Hz (36dB/octave BW).

It is interesting how strongly bass affects our perception of audio. Owning the JBL 4367 I more or less agree Phusis take on them but will add my thoughts as this thread is about bass.

I have been using them with subs for the last year (60-65hz highpass) and recently got rid of my subs (sold one and gave one to a friend) in prep for new subs on order. With the subs the system as a whole is warm and impactful, I can play them very loud with no ear fatigue at all.

But without the subs the speakers seem a touch bright to me (they measure “flat” with a bit of HF roll off in my room). The interesting thing is the subs are the only change and they were measured and adjust flat to 25hz and roll off from there. Now that it has been a month or so without subs the speakers sound a touch warm again. All in all pretty interesting with no change to the mids or highs. Just that lass octave and 1/2.

I don’t have much horn experience other than these speakers and demos of the Klispch line (which I did not really care for if I am being honest). I sit 10’ from my speakers and a well damped room, 7” broad band panels at first reflection points, fully treated ceiling, full carpet, big soft fabric theater seats, so that might play into it too. My UHF adjustment is 0.5db down which makes a bigger difference than one might think.

The 4367 currently is my favorite speaker I have owned, their flaws are minor at their price point and have honestly given me a moment of pause as I am not sure what I would change too. which leads me to changing my subs and trying a more active approach and I plan to dip my toes into digital correction and see how it goes

 

 

Dear @deep_333 : My room geometry is not easy to use the Harman calculator, these are more or less the dimensions/shapes:

as I posted my apartment has 2 parlors from the entrance door. First parlor where is not seated the system its wall distance to the other extreme, where is the second parlor/listening area/system, are 9.70m to the window that’s behind the speakers.

Now the speakers are at 95cm. in front of the windows and the left speaker is at 30cm. from the side wall, the rigth wall is at 8.5m from the left one.

The center of the speaker tweeters in between are at 2.60m and the speaker woofers at 3.05m.

Listening area length is 4.70m and the wide is around 4.5m. Exist a passageway of 1m. wide by 14+m. in length. This apartment has 3 bedrooms and two complete bathrooms. All in one floor, so is a little big.

Dining room is big and the dining room central/rectangular table is for 10 seated people.

Both parlors are full of ( mainly ) wood furniture as the dining room and all around exist wood display cabinet ( like seven of them ). The parlor furniture are made from natural absorbtion materials and due to the shape of the wood furniture it works as difussors.

Rigth now the system is working truly fine and till today I think that I can’t do ( ? ) anything to improve its very high quality MUSIC reproduction and very high resolution.

It does not matters the SPLs the room/system just refuse to distort: MUSIC stage always is there/nothing change but SPL. Yes, its noise floor and distortions levels are so low that can be dangerous to the ears with out taking in count due that we can’t be aware of those distortion levels. No, I normally listen at around 82 or even a little lower db SPL and only during some kind of system audio items tests I listen at 95db with peacks at 105+db for only a few minutes.

@rauliruegas 

I'm having difficulty visualizing this with the written description. Do you have a top view sketch/schematic with distances, etc (that you can post here)? "Picture says a thousand words", Confucius said.

 

I’ve found them too "hot" sounding over longer durations in being more forward and incisive in their sonic nature than my own system. To by fair, in many ways the 4367’s are delightful speakers; exhilarating, energetic, honest, clean, extremely informative (I’d say a wee bit too "insisting") and - apart from the low octave shifting towards a warmer imprinting - fairly coherent.

The thing is though, to my ears and sensibilities they simply become too much over time, and moreover I find string instruments like violins to have a slightly "plastic"-like and/or nasal character to them (I prefer the M2’s and 4349’s here with their flatter waveguide), which is a dealbreaker to me. My EV main speakers by comparison with their large format horns + subs are sonically more akin to large panel speakers; more relaxed, less "beamy," fuller and more visceral/physical/dense. Where it becomes apparent they’re a larger package overall, apart from their more natural height of presentation, is at higher SPL’s (not least with movies) where the sheer unadulterated force and power is at full display.

 

...know about that "plastic’y" sound all too well and it goes all the way up to their top end line. The measurement heavy JBL/Harman PhDs don’t seem to care too much, as long as it measures great! They may need to put their big egos down and learn a thing or two from the likes of Borresen, Yamaha, TAD, etc.

What horn subwoofers do you use? DIY? or something else? I might be interested in getting one.