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how big is your woofer, how big is your box, what's your sensitivity

Seems you are making a huge assumption as to the capabilities of the large woofers in question.
The key is displacement volume (SD x Xmax), those 10"ers will be running close to their xmax/power handling(not to mention the increase in harmonic distortion) to produce a maximum of 95 dB@25hz(thats just 20dB above the threshold of audibility).
My JBL's will be just ticking over at around 20w input to produce that level at 25hz .

http://www.diyaudio.com/forums/atta...ement-spl-chart-displacement-chart-metric.gif
 
Tony L said:
True, though extension is but one factor of many in reproducing realistic bass. I'd argue surface area / air displacement was key too, and there's no established or accepted measurement criteria for that one. I've certainly never personally heard anything less than a 12" driver sound like a real bass instrument. The stuff that sounds real to me is always big, and I include ESLs / panels in that - they do the air displacement thing for sure.
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I don't disagree with you. Subjectively, a large woofer sounds more effortless than a small one, even if they are both operating well within their bandwidth. It has more to do with the way they couple with the air-mass in the room. I have often used the analogy of stirring paint with a paddle vs knitting needle to compare and contrast large woofers vs small ones when it comes to shifting air.

cooky1257 said:
Seems you are making a huge assumption as to the capabilities of the large woofers in question.
The key is displacement volume (SD x Xmax), those 10"ers will be running close to their xmax/power handling(not to mention the increase in harmonic distortion) to produce a maximum of 95 dB@25hz(thats just 20dB above the threshold of audibility).
My JBL's will be just ticking over at around 20w input to produce that level at 25hz .
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Again, I don't disagree with you. You are both missing my point about the need to consider extension against size and sensitivity. Notwithstanding, you are more inclined to feel rather than hear 25Hz, and 95dB is plenty loud for me.
 
I had Amphion TWO15 on test, some year ago. Each speaker has two 15cm bass units, and two 15cm passive unit in back. I was so impressed by bass, it was much better than on my gallo ref 3.5
 
James said:
Again, I don't disagree with you. You are both missing my point about the need to consider extension against size and sensitivity. Notwithstanding, you are more inclined to feel rather than hear 25Hz, and 95dB is plenty loud for me.
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I'd generally accept the sensitivity/extension relationship though fail to see size as mitigating against either.
 
James said:
You're all mostly missing one important parameter - bass extension. It's easy to go big and sensitive, but it doesn't do much if the bottom two octaves are missing in action.

FWIW, I have a pair of 80L loudspeakers with only 10" woofers, but they go down to 25Hz in my room.
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10Hz -6dB in free space.
 
Horrendous levels of 2nd harmonic at anything approaching audibility I'd guess :)
 
James said:
You are both missing my point about the need to consider extension against size and sensitivity.
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I'm not actually, the La Scalas proved a bit of a learning curve in that respect! It came as a shock that these huge laundromat washing machine sized horns really do not have anything at all below about 55Hz! I think this is due to horn-loading more than efficiency as they do not have the gentle roll-off of an infinite baffle nor the out of band flub of a port, they just fall off a cliff once they run out of horn. They are interesting speakers and do some things very well indeed, but they certainly highlight another set of compromises.
 
merlin said:
Horrendous levels of 2nd harmonic at anything approaching audibility I'd guess :)
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Not sure if you're replying to my post, but just in case, the answer is no.
The electronic compensation also linearises the drive units and provides a reduction in distortion of approx 10X.
 
Have just bought a set of Tannoy Cheviots, 12" of woofage, 90Db, 65 litres and 35Kg can't fire them up just now as we have people here but big anticipation.
 
S-Man said:
Not sure if you're replying to my post, but just in case, the answer is no.
The electronic compensation also linearises the drive units and provides a reduction in distortion of approx 10X.
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What are these beasts of which you speak?
 
James said:
You're all mostly missing one important parameter - bass extension. It's easy to go big and sensitive, but it doesn't do much if the bottom two octaves are missing in action.

FWIW, I have a pair of 80L loudspeakers with only 10" woofers, but they go down to 25Hz in my room.
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Correct, i'm -3dB @17Hz, love transmission lines.
 
cooky1257 said:
What are these beasts of which you speak?
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I'd be interested too. I've not come across a 10" drive unit that can remain linear over the excursion required to produce loud bass at those sorts of frequencies.
 
Since getting big speakers I've listened to music less loudly on average.

Maybe it's because of age, but it's unexpected because I could rock the Casbah with just a couple of watts.

Joe
 
Sorry chaps, I cannot tell you much about them because the IP belongs to a friend of mine.
However, they were demoed at Scalford in 2012 so despite some members concerns that they are just dreamware, they do actually exist.

So what can I tell you...
They use a novel method of drive unit control using electronics to cancel out some of the drive unit parameters. The result is that the driver does not care what size of box it is in and it inherently has a 1st order lf rolloff. It also does not matter (within reasonable limits) what drivers are used, I chose 7" drivers to fit in an 8" wide box to match my main speakers, 3 was the maximum number I could accommodate vertically. The designer told me that theoretically this is not enough cone area to provide high output at 20Hz, experience has shown that is it adequate for 99.9% of music recordings but certainly not for home theatre - there is some serious stuff on movie soundtracks at well below audible frequencies!

The interesting thing (to me anyway) is that the lower I set the lf rolloff frequency the tighter the bass gets. I speculate that this is due to improved group delay. The other interesting thing is that room interaction is much less apparent that when I used to run ported 2-ways with much less lf bandwidth. Final point - they are not bass monsters i.e.they don't do Wilson style bass.
 
Forgive my wanting more information S Man. It's just that your friend seems to have destroyed the laws of physics yet there's nothing about them anywhere.

At my age I do tend to take this sort of thing with a pinch of salt. There is a big difference between the sensation of bass and a true high level clean bottom octave. IME, 20hz should be felt rather than heard by most people and you are referring in infrasonic frequencies below that.

I hope you can find some more information on this technology and share at some point. There's certainly some interesting home cinema developments from the US with regards to servo control and feedback.
 
Rythmik Audio do something similar albeit using servo feedback. They state that it's worth going down to 14Hz to get a more solid sounding bottom end response.

My friend has not destroyed the laws of physics, he has used the laws physics and has reams of maths proving the theory of how they work. It took him 10 years of research and experimentation to get to this point.

It's perfectly OK to take this with a pinch of salt. My friend has got the same response from various industry experts at AES conferences etc. Everone else seems to be stuck on box tuning and playing around with mechanical parameters.
 
S-Man said:
Sorry chaps, I cannot tell you much about them because the IP belongs to a friend of mine.
However, they were demoed at Scalford in 2012 so despite some members concerns that they are just dreamware, they do actually exist.

So what can I tell you...
They use a novel method of drive unit control using electronics to cancel out some of the drive unit parameters. The result is that the driver does not care what size of box it is in and it inherently has a 1st order lf rolloff. It also does not matter (within reasonable limits) what drivers are used, I chose 7" drivers to fit in an 8" wide box to match my main speakers, 3 was the maximum number I could accommodate vertically. The designer told me that theoretically this is not enough cone area to provide high output at 20Hz, experience has shown that is it adequate for 99.9% of music recordings but certainly not for home theatre - there is some serious stuff on movie soundtracks at well below audible frequencies!

The interesting thing (to me anyway) is that the lower I set the lf rolloff frequency the tighter the bass gets. I speculate that this is due to improved group delay. The other interesting thing is that room interaction is much less apparent that when I used to run ported 2-ways with much less lf bandwidth. Final point - they are not bass monsters i.e.they don't do Wilson style bass.
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Thanks.
Servo control or not a cursory examination would indicate you need your 6x180mm drivers to have an xmax of +/-25mm to produce 92dB at 12hz
So I'm unclear how given the inescapable mechanical limitations of all drivers how it can't matter particularly what drivers are used, it in fact would indicate a very specific driver spec/requirement.
Pity you can't elaborate more, the Meyer X10 is a servo controlled monitor that sounds awesome, so the tech is there for sure but they manage to stay within the laws of physics.

http://meyersound.com/sites/default/files/x-10_ds.pdf
 
As I said, IME there is very little on music CDs below 35Hz so I don't tend to run out of excursion. DVD sound is an entirely different kettle of fish and if this were my main application I would either increase the lf corner and/or get (lots) more drive unit area.
 
The system is 6dB down at 10Hz. That is its measured response. In practise, since there is nothing below about 35Hz on 99.9% of CDs I don't have a problem with excursion. On DVD soundtracks, the drivers hit their endstops dramatically at high SPLs.

All this has already been stated (sorry if it's not clear). The reason to extend the bass to such a low freqeuncy is not to hear, or feel, extra stuff - it's so that the stuff that is there is played at the correct time and stops when the signal stops.
 
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