Why a 3" driver can give "good" bass

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#42
These might be of interest 😉

BaryBass

The BaryBass from Philips is the world's first miniature, low-frequency sub-woofer. This ground-breaking development in audio technology allows deep bass reproduction from a small loudspeaker enclosure; something that has long been considered a kind of a 'holy grail' in the audio world. The BaryBass opens up a whole new range of possibilities in adding a true bass sound to integrated flat TV loudspeakers, miniature portable digital audio players and even in-car entertainment systems.

Philips Research Technologies - Philips' BaryBass technology
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IMPROVING PERCEIVED BASS AND RECONSTRUCTION OF HIGH FREQUENCIES FOR BAND LIMITED SIGNALS

ABSTRACT

Bandwidth extenstion methods are required in systems that playback bandlimited signals (e.g. telephone, MP3) or that are not capable of reproducing signals with a large bandwidth (small or inexpensive loudspeakers). The first part of this paper deals with reproducing low pitched signals through small loudspeakers. This work is based on psychoacoustic phenomena to invoke a deep bass impression using only higher frequency components. The second part of this paper deals with high-frequency bandwidth extension of music and speech. In this method, no additional information on the original wide band content is required. It aims at providing a more pleasant and brighter sound impression.

www.extra.research.philips.com/hera/people/aarts/RMA_papers/aar02n4.pdf
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Philips Dynamic Ultra Bass US patent 6,134,330

To improve the perceived audio signal, it is known to use a harmonics generator to create the illusion that the perceived audio includes lower frequency signal parts than really available. In addition to improving the perceived so called ultra bass signals (for example 20-70 Hz) also the signals in the frequency band between the ultra bass signal and the normal audio signal are improved.
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#43
Yes, and I agree with that Bob. But I think bass sounds better on a bigger woofer that can reach deeper. Even though I think the mid range of a 4" sounds better. So the attack part of a kick drum will sound better (generally) on the small diameter driver, but the thump will sound better on the larger woofer. I do believe these can be evaluated independently. Kevin seems to think that isn't possible. I think that's coming from the notion that the music must bring the bass and mids together, which is true. Which is why I'd ultimately take the 4" driver. So far I haven't heard a 3" driver that can do it for me. The ultimately sacrifice to much of the "thump" to satisfy me.
 
#44

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#45
tuxedocivic said:
Yes, and I agree with that Bob. But I think bass sounds better on a bigger woofer that can reach deeper.
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I would also agree it is often the case, but that is not to say you can't get deep bass from a full-ranger. The methods that will help you do this include:

1. Use an array of more than 1 (but choose a driver with low Fs to start with). Start with at least 4" driver.
2. Use significant cabinet loading - transmission line is good
3. Make sure cabinet design has been optimised for good response curve
4. Make sure baffle-step correction is sufficient
5. Make sure amp has sufficient power to drive the bass (which will be more power hungry than the equivalent large woofer design)

Get it all right and yes you can get match most commercial (compact domestic) large woofer systems, infact few people will believe your bass capability (from such a small cabinet footprint) until you demo it!
 
#46
Zero D,
Thanks for the links to the Phillips technologies for psychoacoustic methods to improve the 'perception' of deep bass. If I am reading this right, the harmonic distortion for such a system where the sub is a one-note (literally because it operates only at resonance) tone, the harmonic distortion could well be in the several hundred percent levels.
 
#47
Can't believe people still don't understand that deep bass from small speakers is possible. I've made enough mentions of the bose soundlink mini, which produces 'REAL' bass, not just a thump, but well defined solid bass able to produce the harmonic bass products of the music.
It will obviously not beat a subwoofer when it comes to films which demand great bass power and the fact it only goes as low as 55hz with a steep rolloff there after.
Go for a demo and play a music track known for good tuneful bass. The only downside is the stereo stage, which having only a seperation of approx 4inch between left and right drivers is not going to give much spatial spread.
I'm sounding like some bose salesman, but this is the level you need to match if you are planning a diy small speaker and I don't think anyone could match this little bose
 
#49
Bob Brines said:
The frequency in the little white box if you can read it is 41.20Hz. The fundamental is nearly 20dB below the first overtone at 82.4Hz. This is, of course the open E-string, and a perfect example of why string players avoid open strings when possible. However, the bottom line here is that even small speakers can convincingly produce very low notes. (Some one elsewhere posted a spectrum on a 4-string bass guitar. The fundamental was only down 6dB!)
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It really depends on the placement and type of the pickups that track the movement of the bassguitar strings. I play bassguitar myself and I've designed/build several bassguitarcabinets. The sweetspot for the tuning of the port of such a cabinet is IME around 48hz if you also want the low B to be heard with some heft. If you would tune to 80hz you would indeed have enough bottom end to amplify the 2nd harmonic of the low E, but when you switch to a basscab that has more low-end extension you definitely hear that you miss something in the lowest octave with the higher tuned one.
Btw. I also play EUB(electric upright bass) and I have designed a small horn-reflex enclosure with an 8" driver for it. The tuning is approx 70hz and it really works great with the piezo pickup of the EUB.

As for 3" drivers producing bass, I have a Tangband W3-1364sa, right now it's running in 4liters tuned to approx 70hz and there's definitely bass comin' out of that tiny driver, though I think the driver will feel more comfortable in a TL of approx 1.2mtrs long.
 
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#50
If I read you right, you are indeed tuning your cabinets to fogo the fundamental of the bottom E or B string. This makes sense as it greatly reduces cabinet size and power requirements that would be required for a basically inaudible frequency. The "punch" or "thump" in rock music is usually up around 80Hz anyway.

My only comment about missing the fundamental is that in orchestral music, where it is common to have as many as a half dozen double basses, fundamentals off of the E string can be felt.

Bob
 
#51
Bob Brines said:
If I read you right, you are indeed tuning your cabinets to fogo the fundamental of the bottom E or B string. This makes sense as it greatly reduces cabinet size and power requirements that would be required for a basically inaudible frequency. The "punch" or "thump" in rock music is usually up around 80Hz anyway.

My only comment about missing the fundamental is that in orchestral music, where it is common to have as many as a half dozen double basses, fundamentals off of the E string can be felt.

Bob
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Indeed, tuning to the fundamental would make the cabs to big so most of the time basscab-makers choose some tuning inbetween.
 
#52
arjank said:
I think the driver will feel more comfortable in a TL of approx 1.2mtrs long.
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Yes, exactly right. Mass (port) loaded will shorten this. This is actually an advantage of full-range drivers; you only need one main cabinet cavity so the whole cabinet can be used. 3-ways, often require separate cavities and the bass loading is limited by the largest cavity, so you end up with a massive box to get the fullest bass. With a descent FR design You can get decent bass that only starts dropping off drastically in the 20's with some good design and it is not the driver size but the cabinet that is doing it. The driver is effectively converting electrical power into spl at the cabinet port (and may not indeed be moving much at all). This is the key concept of 'loading'. With this design driver power handling is key (go for relatively high RMS), then drive it with a descent powered solid-state amp (in-fact need not be anything expensive).
 
#55
Returning to post #1, speakers with small drivers are not producing 40Hz, they are producing 80Hz. The speaker's F3 is probably in the 60Hz range anyway. Discussing distortion at 40Hz is irrelevant since there is no sound, hence no distortion. At 80Hz the distortion levels may be rather well behaved.

Bob
 
#57
Bob Brines said:
Returning to post #1, speakers with small drivers are not producing 40Hz, they are producing 80Hz. The speaker's F3 is probably in the 60Hz range anyway. Discussing distortion at 40Hz is irrelevant since there is no sound, hence no distortion. At 80Hz the distortion levels may be rather well behaved.

Bob
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Ah, have to disagree with you there. Unless you use a HP filter the signal will reach the driver. The port is a short for the fundamental tone, but not for harmonic distortion, so that is ALL that the driver is producing.

I experienced this with a 15" 2x PR subwoofer system that I once built. The tuning was in the low to mid 20's and a group of us were listening to the system play organ music. There was a very low 16Hz pedal passage and there was suddenly some audible tones coming out of the sub. Someone leaned over to me and said "that's all distortion" and he was right!

If you look at the plot in post #4 of this thread, you see exactly this phenomenon. For example at 30Hz the frequency response of the system is down and is crossing the distortion curves - that is 100% distortion! Distortion doesn't "go away" just because the system can not generate much SPL at that frequency. The distortion level is only down about 25dB from the passband level of the system and will definitely be audible on a pure tone. For music, it might only be coloration which some may even enjoy but nonetheless its not great fidelity.
 
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#58
Wait, when did we bring multiple drivers into this? How does a 3" physically offer just as much Vd as a 12" all else equal. Who can't hear 40hz? Why do multiple drivers require more power than a single? Since when is distortion considered HiFi?
 
#59
I don't buy it. Your saying I could turn my sub off and not miss it? And an organ playing g and c has a beat freq that sounds lower, it's not a brain thing. If your right, why bother with 32' pipes when there not needed?
 
#60
And I've never heard 3 inch speakers with good bass, and I doubt any filtering will help. If there was a practical way of doing this I'm sure in these days of everyone wants small speakers, one of the large manufacturers (Sony, Bose, etc) would be doing it.
 
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