Big subs vs Small subs

[ex audiophile]

So I was considering the pros and cons of large vs small subwoofers. Clearly if you need to reproduce 10hz at 100+ db you need a large driver, something from JTR, Funk etc.

But what if you're producing 20 hz at 90db? Does a large driver, say 18" sound different than a small driver, say 12" assuming equal spl and distortion? The frequency range of the cello and double bass overlap, so do they sound the same when producing the same frequency at the same volume?
I don't know, but if the large and the small driver are both moving the same quantity of air at the same frequency they should sound the same. The smaller driver just has to make a larger excursion with each cycle. Would enjoy hearing thoughts of others.

 

[AdamG]

So I was considering the pros and cons of large vs small subwoofers. Clearly if you need to reproduce 10hz at 100+ db you need a large driver, something from JTR, Funk etc.

But what if you're producing 20 hz at 90db? Does a large driver, say 18" sound different than a small driver, say 12" assuming equal spl and distortion? The frequency range of the cello and double bass overlap, so do they sound the same when producing the same frequency at the same volume?
I don't know, but if the large and the small driver are both moving the same quantity of air at the same frequency they should sound the same. The smaller driver just has to make a larger excursion with each cycle. Would enjoy hearing thoughts of others.

Pure subjective experience and opinion here. I had dual SVS Ultra’s 13” subs. Upgraded to dual JTR Captivators 18” subs. The tactile energy they push into the room is palpable. Before with the SVS Subs you mostly hear them. The JTR’s you hear and feel. The weight of the bass is difficult to describe without using a bunch of nonsense subjective terms. It wasn’t an incremental improvement. It was a complete paradigm shift. Saying night and day would be an understatement. With subs displacement and size make a huge difference in the experience. If you’re a Basshead. Get the biggest driver’s you can afford and then thank me later. 12 inchers are not going to fairly compete with 18” drivers. If you have close neighbors or live in a multi family building get the 12’s and you might get away with it. The JTR’s are definitely going to piss off any close neighbors.

Good luck with your search and decision.

 

[sarumbear]

Big sub has the potential to be better but not necessarily so. Learn the criteria for what makes good for you then compare the specs. There are great sites to allow you to compare specs but you need to know what is good for you first b

 

[dasdoing]

The tactile energy they push into the room is palpable. Before with the SVS Subs you mostly hear them. The JTR’s you hear and feel.

this would be for the same SPL? if so, what explains this?

 

[chych7]

this would be for the same SPL? if so, what explains this?

No! It would be sound intensity. Microphones don't measure sound intensity, just sound pressure. We are blind to measuring tactile effects effectively, those type of sensors are uncommon/lab experimentation grade.

 

[AdamG]

this would be for the same SPL? if so, what explains this?

Tactile energy and air movement. Not certain about the science of why. More air compression. @20hz a 12” is pushing it’s limits @20hz the 18” has plenty of headroom and is not compressing. Size of enclosure difference also contributes to the effect. Some of this can be contributed to the same phenomenon of how towers sound larger and wider than Stand-mount speakers. Just guessing here.

 

[kemmler3D]

Does a large driver, say 18" sound different than a small driver, say 12" assuming equal spl and distortion?

Basically no*, although the 12" will tend to have more distortion at a given SPL in real life, so "assuming equal SPL and distortion" is slightly unrealistic.

The frequency range of the cello and double bass overlap, so do they sound the same when producing the same frequency at the same volume?

No, because musical instruments produce a lot of harmonics and resonances on top of the fundamental (on purpose, to sound good), this is what makes them sound unique. But this is exactly what you don't want speakers to do.

*notwithstanding putative tactile effects

 

[kemmler3D]

No! It would be sound intensity. Microphones don't measure sound intensity, just sound pressure. We are blind to measuring tactile effects effectively, those type of sensors are uncommon/lab experimentation grade.

This is something of a new concept for me, can you elaborate and/or link to something that goes into more detail?

 

[Keith_W]

Pure subjective experience and opinion here. I had dual SVS Ultra’s 13” subs. Upgraded to dual JTR Captivators 18” subs. The tactile energy they push into the room is palpable. Before with the SVS Subs you mostly hear them. The JTR’s you hear and feel. The weight of the bass is difficult to describe without using a bunch of nonsense subjective terms. It wasn’t an incremental improvement. It was a complete paradigm shift. Saying night and day would be an understatement. With subs displacement and size make a huge difference in the experience. If you’re a Basshead. Get the biggest driver’s you can afford and then thank me later. 12 inchers are not going to fairly compete with 18” drivers. If you have close neighbors or live in a multi family building get the 12’s and you might get away with it. The JTR’s are definitely going to piss off any close neighbors.

Good luck with your search and decision.

Yeah, that is my experience as well. It was explained to me that it was about the "size of the wavefront" which did not make sense. I wonder if there is an objective measurement that shows what is going on.

 

[Sokel]

This is something of a new concept for me, can you elaborate and/or link to something that goes into more detail?

14.2 Sound Intensity and Sound Level - Physics | OpenStax

In a quiet forest, you can sometimes hear a single leaf fall to the ground. But in a traffic jam filled with honking cars, you may have to shout just so...

openstax.org

 

[dasdoing]

No! It would be sound intensity. Microphones don't measure sound intensity, just sound pressure. We are blind to measuring tactile effects effectively, those type of sensors are uncommon/lab experimentation grade.

Tactile energy and air movement. Not certain about the science of why. More air compression. @20hz a 12” is pushing it’s limits @20hz the 18” has plenty of headroom and is not compressing. Size of enclosure difference also contributes to the effect. Some of this can be contributed to the same phenomenon of how towers sound larger and wider than Stand-mount speakers. Just guessing here.

I have a hard time understanding that two omnidirectional soundwaves of the same SPL can have diferent effects, but I will study sound intensity.
in the case of big speaker vs small speaker the diferences in dispersion can explain (small speaker stays omni for longer going up the frequency range)

 

[RayDunzl]

No! It would be sound intensity. Microphones don't measure sound intensity, just sound pressure.

SPL is pressure at a point in pascals.

Intensity is pressure over an area in watts.

 

[Urubamba]

I built two of these, they are corner cabinets with Eminence PA speakers.
I needed to hear those first two octaves.
Goal accomplished.
To achieve the same with smaller speakers, the cabinet would need to be much larger. Hoffmann's famous Iron Law.

" If size is not a limiting factor, we can get really low bass and very high efficiency.

If size is restricted, we have to sacrifice efficiency - or low-end extension.

If you want high efficiency - and small volume - you have to sacrifice deep bass. "

 

[chych7]

I realized the significance of sound intensity from this AVSforum thread.

For HT applications, there's often the hunt for the elusive mid-bass "chest slam". Turns out all you need is an inexpensive ported PA sub, placed right behind your seat to achieve this. Far stronger than a typical 15" HT sub with low frequency port tuning. I have a Behringer B1200D in my system and it gives a huge amount of tactile response (but it did need quite a bit of tuning with a miniDSP to blend well with my main subs and speakers, when looking at SPL vs. freq smoothness).

 

[dasdoing]

Turns out all you need is an inexpensive ported PA sub, placed right behind your seat to achieve this.

I had a sealed 12" behind my couch for a while. couldn't stand it, my ass would vibrate all the time lol. It's cool for 1 or 2 days, but starts to get anoying very fast

 

[Chrispy]

Pure subjective experience and opinion here. I had dual SVS Ultra’s 13” subs. Upgraded to dual JTR Captivators 18” subs. The tactile energy they push into the room is palpable. Before with the SVS Subs you mostly hear them. The JTR’s you hear and feel. The weight of the bass is difficult to describe without using a bunch of nonsense subjective terms. It wasn’t an incremental improvement. It was a complete paradigm shift. Saying night and day would be an understatement. With subs displacement and size make a huge difference in the experience. If you’re a Basshead. Get the biggest driver’s you can afford and then thank me later. 12 inchers are not going to fairly compete with 18” drivers. If you have close neighbors or live in a multi family building get the 12’s and you might get away with it. The JTR’s are definitely going to piss off any close neighbors.

Good luck with your search and decision.

I think this is somewhat beyond the OPs proposed use test case. I'd agree, and am not going smaller from my 18s particularly.

 

[chych7]

I had a sealed 12" behind my couch for a while. couldn't stand it, my ass would vibrate all the time lol. It's cool for 1 or 2 days, but starts to get anoying very fast

Yeah I would emphasize that tuning and integration is very important. Took me a while to get it to sound right and have just the right amount of tactile response. I use a miniDSP with Multi Sub Optimizer; had to play with the target curves and the crossovers/slopes on the miniDSP a bit.

 

[ex audiophile]

14.2 Sound Intensity and Sound Level - Physics | OpenStax

In a quiet forest, you can sometimes hear a single leaf fall to the ground. But in a traffic jam filled with honking cars, you may have to shout just so...

openstax.org

Excellent reference, thanks

 

[Zapper]

At the same frequency and amplitude (SPL) two subs of different size should sound (and feel) the same. They both impart the same energy to the sound field. The differences noted for the 18" sub are because it produces frequencies and SPLs that the 12" just can't.

 

[Waxx]

Even a 5" can produce 10Hz and have low distortion, but only on a very low volume. the bigger the driver, the louder it can go on that frequency. And the harder you drive a driver to it's limits, the more distortion it makes. So a 18" and a 12" at the same frequency and volume will not necesairly sound the same, as the 18" wil probally have way more headroom and less distortion than the 12" (depending on the model and cabinet) as you use less of it's capacity of producing that frequency. It's similar as with amps and headroom.