Big subs vs Small subs

[sarumbear]

Not sure those small units meet any definition. They are different from a sealed box, and they are different from a ported box, so I call it a horn. Usually, the horn channel has a cross sectional area that increases towards the mouth.

A horn shape has been defined since the 18th century. It’s unnecessarily confusing to call a different shape, a horn.

 

[jhaider]

Examples of designs can be found in the product section on my web site,

The smallest current model sub on your website appears to be this one:

Kvalsvoll Design T6-A

www.kvalsvoll.com

It's roughly 16.5" by 16.5" by 7.5" (420mm/420mm/188mm). While that's roughly 2x the exterior volume of the sub I referenced, or KEF KC62/this teeny little thing I picked up recently to try out for desktop use, I don't ski and presumably ski boots come in bigger boxes than Alden 405s do. Your T6 is smaller than anything measured at data-bass, with a total external volume of <1.2 cubic feet - roughly the size of the OG Peerless XLS10 "application note" PR sub, or 2/3 the size of a commercial sub such as SVS SB12/SB2000 or JL Audio E110. I would quibble with calling it a "horn" - it looks like a vented cabinet tuned to ~30Hz from your pictures and data, though the measurements you post show excellent control of out of band resonances between the design and the highpass. I also echo @gnarly in appreciating the fulsome set of measurements for your subs.

It's a reasonable approach, though my preference a larger piston in a simpler box (and likely need lots more power as well). Perhaps it's prejudice, but I've usually found systems that can excite modes below their nominal cutoff (i.e. closed boxes and 4th order bandpass boxes) to be the most satisfying in terms of tactile bass. Others would prefer greater in-passband efficiency, and that seems like a reasonable option too.

 

[Head_Unit]

my ass would vibrate all the time lol.

Are you sure it wasn't the chili and beer?

 

[Head_Unit]

Does a large driver, say 18" sound different than a small driver, say 12" assuming equal spl and distortion?...if the large and the small driver are both moving the same quantity of air at the same frequency they should sound the same.

Essentially you are saying "if they are moving the same air won't they sound the same?"
Well, er, yes. If they produced exactly the same waveform, it would have to sound identical. BUT that is extremely difficult, speaking as a loudspeaker engineer. The bigger driver will move less, which means less Doppler distortion.* The bigger driver can also have a larger surround and larger spiders, which then the reduced motion will distort those less than a longer-stroking smaller diameter driver. The bigger driver may also have a larger voice coil, equating to less distortion related to heating of the voice coil. The lesser motion makes it easier to keep within a more linear portion of the magnetic field.
--> A bigger driver is easier to have lower distortion
although it really depends on specifics. To add to the wild broad statements subject to specifics, a larger driver in a larger box can be more easily made to deliver output at the lowest frequencies.


*recently Purify has said this is not so important, though Paul Klipsch thought it was.

 

[dasdoing]

Are you sure it wasn't the chili and beer?

I eat a lot of beans and use protein shakes, too....so I do fart a lot.
but the frequency is a lot higher lol

 

[ex audiophile]

Essentially you are saying "if they are moving the same air won't they sound the same?"
Well, er, yes. If they produced exactly the same waveform, it would have to sound identical. BUT that is extremely difficult, speaking as a loudspeaker engineer. The bigger driver will move less, which means less Doppler distortion.* The bigger driver can also have a larger surround and larger spiders, which then the reduced motion will distort those less than a longer-stroking smaller diameter driver. The bigger driver may also have a larger voice coil, equating to less distortion related to heating of the voice coil. The lesser motion makes it easier to keep within a more linear portion of the magnetic field.
--> A bigger driver is easier to have lower distortion
although it really depends on specifics. To add to the wild broad statements subject to specifics, a larger driver in a larger box can be more easily made to deliver output at the lowest frequencies.


*recently Purify has said this is not so important, though Paul Klipsch thought it was.

Quotes imply a word for word replication of the original. What I, er, actually said was "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."

I realize that larger drivers have advantages, but that wasn't my question. If both the large and smaller drivers are operating within their normal operating range at the same frequency, and have equal distortion, are you saying the waveform is different and therefore the sound is different? For instance both the JLA e112 and the JTR sealed 18 easily output 90db at 20 hz (Database) and my conclusion from the commentary is that under those conditions you could not tell them apart in a blinded test environment. I'm assuming similar distortion with these two quality subs but I could not find a reference for distortion.

 

[Deleted member 58722]

The truth

 

[fpitas]

*recently Purify has said this is not so important, though Paul Klipsch thought it was.

Mathematics says it is, too.

This rather odd demonstration on their site seems to disprove their assertion:

Doppler distortion vs IMD? - PURIFI

Let’s get this out of the way first: Doppler distortion is a form of IMD. This is interesting because IMD in general tends to get little interest on loudspeaker forums, whereas Doppler distortion is often made a big deal of. Any distortion process will cause both harmonic and intermodulation...

purifi-audio.com

That FM modulation sounds terrible to me. I wonder if it's the case that different people can hear it, or not.

 

[puppet]

What I, er, actually said was "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."

The problem with your statement above is a smaller driver doesn't react with the atmosphere in the same way a larger driver does. It comes down to radiation resistance. The lower radiation resistance of the smaller driver can only be improved by employing a larger cone area to react with the atmosphere as frequency drops. Increased excursion does not do that. Increased excursion is increased amplitude not increased force on the surrounding atmosphere. The atmosphere is the load. It is capable of absorbing cone energy but that cone needs to be larger in size.

 

[ex audiophile]

The problem with your statement above is a smaller driver doesn't react with the atmosphere in the same way a larger driver does. It comes down to radiation resistance. The lower radiation resistance of the smaller driver can only be improved by employing a larger cone area to react with the atmosphere as frequency drops. Increased excursion does not do that. Increased excursion is increased amplitude not increased force on the surrounding atmosphere. The atmosphere is the load. It is capable of absorbing cone energy but that cone needs to be larger in size.

I did not state that the drivers move the atmosphere in the same way, perhaps you should read the original post. My question from the beginning is can you hear a difference between a larger and smaller sub playing the same frequency at the same volume with the same distortion? The differences between driver size regarding distortion and the difference in the radiation pattern are interesting but the conclusion seems to be that you cannot tell the difference. Are you saying that because of "radiation resistance" you CAN hear a difference in this scenario?

 

[Kvalsvoll]

The smallest current model sub on your website appears to be this one:

Kvalsvoll Design T6-A

www.kvalsvoll.com

It's roughly 16.5" by 16.5" by 7.5" (420mm/420mm/188mm). While that's roughly 2x the exterior volume of the sub I referenced, or KEF KC62/this teeny little thing I picked up recently to try out for desktop use, I don't ski and presumably ski boots come in bigger boxes than Alden 405s do. Your T6 is smaller than anything measured at data-bass, with a total external volume of <1.2 cubic feet - roughly the size of the OG Peerless XLS10 "application note" PR sub, or 2/3 the size of a commercial sub such as SVS SB12/SB2000 or JL Audio E110. I would quibble with calling it a "horn" - it looks like a vented cabinet tuned to ~30Hz from your pictures and data, though the measurements you post show excellent control of out of band resonances between the design and the highpass. I also echo @gnarly in appreciating the fulsome set of measurements for your subs.

It's a reasonable approach, though my preference a larger piston in a simpler box (and likely need lots more power as well). Perhaps it's prejudice, but I've usually found systems that can excite modes below their nominal cutoff (i.e. closed boxes and 4th order bandpass boxes) to be the most satisfying in terms of tactile bass. Others would prefer greater in-passband efficiency, and that seems like a reasonable option too.

What those graphs for the T6 does not show is the output from the port (I tend to call it port, because that is what it looks like, doesn't really give the impression of a large horn mouth..). This port output contributes significantly to the sound all the way up to around 100Hz, and this is different from an ordinary ported box, where port contribution is a quite narrow band around the tuning. So the acoustic loading of the driver is different, it has a wider frequency bandwidth.

The intention of this small design was to make a very small unit with sound character similar to the larger bass systems. It can not play very loud, but if that is never required, it is nice to have smaller subwoofers, and if the sound is similar for low and medium volume levels, there is no benefit of having a larger system.

 

[puppet]

Yes, that's what I'm saying ex audiophile. The fact that both drivers, large and small, react differently to the atmosphere means they will each have an individual perceived sound to them. As an example, a low tone produced by each driver may not be heard by the smaller driver even though the cone is moving violently. It's radiation resistance is too low. Therefore, large vs small, sound different.

 

[ex audiophile]

Yes, that's what I'm saying ex audiophile. The fact that both drivers, large and small, react differently to the atmosphere means they will each have an individual perceived sound to them. As an example, a low tone produced by each driver may not be heard by the smaller driver even though the cone is moving violently. It's radiation resistance is too low. Therefore, large vs small, sound different.

well, puppet, when you have evidence of an audible difference i'd love to read all about it.

 

[Puddingbuks]

I eat a lot of beans and use protein shakes, too....so I do fart a lot.
but the frequency is a lot higher lol

 

[puppet]

well, puppet, when you have evidence of an audible difference i'd love to read all about it.

You're joking, right? There are studies the predate my birth on this subject ... and I'm an old guy. Crack a book.

 

[sarumbear]

This port output contributes significantly to the sound all the way up to around 100Hz, and this is different from an ordinary ported box, where port contribution is a quite narrow band around the tuning. So the acoustic loading of the driver is different, it has a wider frequency bandwidth.

In other words the port resonance has lower Q than it normally is? If I’m not mistaken low Q port design was analysed by R. Small on his Ph.D. thesis.

 

[audiofooled]

well, puppet, when you have evidence of an audible difference i'd love to read all about it.

I do think we truly need science to test any hypothesis and come up with an evidence. But if I may, when it comes to subwoofers, they are specialized in playing low frequencies. If they are in a domestic environment, and not outdoors, the room will dominate. As we all know, we need multiple subs, DSP, room treatment.

My point is, put a single sub at different locations in room, chances are it will sound different in comparison to itself. On more complicated waveforms, and not only single frequency, chances it will sound different are a lot greater.

I suppose It is possible to come up with a test of two different subs and make them sound "the same", at least occupying the same location which is hardly possible, or use DSP to make them audibly the same in a blind test.

Why not take advantage of wide variety of subs and pick one or more to one's liking?

 

[sarumbear]

Yes, that's what I'm saying ex audiophile. The fact that both drivers, large and small, react differently to the atmosphere means they will each have an individual perceived sound to them. As an example, a low tone produced by each driver may not be heard by the smaller driver even though the cone is moving violently. It's radiation resistance is too low. Therefore, large vs small, sound different.

but that’s the difference due to the enclosure tuning, which is reflected in the frequency response. If a small and a large driver both tuned the same way with the same f3, Qt and slope, will they sound different?

 

[ex audiophile]

@Ron Texas I'm headed your way

 

[Ron Texas]

@Ron Texas I'm headed your way

Literally or figuratively?