Barybass From Philips

[sagarverma]

hi
i stumbled upon the following link bout something which philips calls as barybass.
http://www.research.philips.com/tech.../dsp/barybass/

anyone heard b4?technical knowledge?

is it similar to ELF sub woofer on esp site?

pour in any knowledge u got

[timpert]

Hi,

From what I can read it is not an ELF by far. The ELF works by operating a closed box woofer below its resonance frequency, compensating the resulting 12dB/oct dropoff electronically. This is very inefficient, but it results in a very compact woofer box without having to resort to passive radiators, bass-reflex or other stored energy effects.

From what I read, I guess the Barybass speaker is a speaker in a closed box with a very high Q tuning. That would mean weak suspension, weak (=cheap) motor and a very large excursion capability in order to displace enough air. By means of some signal processing, an entire band is "mapped onto this singe frequency" that can indeed be reproduced by a fairly small box, with little power. But the bass note takes some time to gain strengt, and also it doesn't stop instantly, as you must expect from a transducer that relies on a strong resonance. So I guess that the net effect would be a single-note bass, amplitude modulated as needed, from a very small piece of <dirty word suppressed>. Nice for boomboxes and HT of the kind where looks are more important than performance. But for serious audio enthousiasts, something to steer away from.

But on the other hand, I may be wrong on this, and Philips might totally surprise us. But based on their description, I doubt this.

btw, isn't the loudspeakers forum a more appropriate place for this post?

Jurgen

[dhaen]

btw, isn't the loudspeakers forum a more appropriate place for this post?

Yup, moved

[sagarverma]

i suppose that the picture of barybass painted by u out here is very mediocer(of barybass).

i read on a site which claims it to be revulutionary.reason being that cheap woofers(loose and small magnets) in wierd shaped small boxes r made to deleiver the performances that r found in high quality woofers placed in voluminous boxes.

what particularly amuses me is the claim of huge spl generated by woofer in small box ,with high effeciency.small box,huge spl without using too much power......wow! its ideal for car.4 to five small monsters in the boot


there is very little technical info available on the subject.any light on the subject is welcome.

[RJ]

From what I read, I guess the Barybass speaker is a speaker in a closed box with a very high Q tuning. That would mean weak suspension, weak (=cheap) motor and a very large excursion capability in order to displace enough air. By means of some signal processing, an entire band is "mapped onto this singe frequency" that can indeed be reproduced by a fairly small box, with little power. But the bass note takes some time to gain strengt, and also it doesn't stop instantly, as you must expect from a transducer that relies on a strong resonance. So I guess that the net effect would be a single-note bass, amplitude modulated as needed, from a very small piece of <dirty word suppressed>. Nice for boomboxes and HT of the kind where looks are more important than performance. But for serious audio enthousiasts, something to steer away from.

Well I'm both a serious audio enthousiast and I like to have fun. I build speakers for both. It really helps understand what's going on underneath all that theory. I've built a test box using a 15" MCM aluminum woofer with a Qts of 1.44 in a 4.0 cu. ft. sealed box. It calls for a 43 cu. ft. box. In the pic the white line is the 1 15" woofer the yellow a 12" Goldwood with a Qts of 2.0 in the same size box (4 cu. ft.)... The other 2 graphs are for 2 drivers respectfully.
I tuned it to 60 hz to accentuate the kick drum which is compressed on many recordings and so far it's working really good. I'm in the process of building a wwmtm using the 2 - Goldwood 12's in a 8 cu. ft. box. You're statement that stored energy at resonance creates a one note bass got me curious. On WinIsd the group delay is also peaked at 60 hz but doesn't exceed 15 ms. Is this the cause and effect of stored energy. I don't hear a one note bass unless the song was written for it, like disco & hip-hop. On jazz it really brings out the stand up bass and the lower half of the piano which is also compressed in recordings.
Well, back to group delay, on other boards and discussions on the subject, it doesn't become a factor in sound quality until it exceeds 22 ms and some say 29 ms.
I did test an 8" high Qts driver in an Aperiodic box and almost got the resonance flattened, but I didn't notice the bass being tighter.
On ported boxes, sometimes I see a group delay in the mid 20's and there are 2 of them. I don't seem to care for bass in ported boxes and I think that might be the cause.
The best sounding bass comes from my line arrays. This may be due to a low group delay ( sealed box) and phasing.
I'm not knocking your analysis. It just peaked my curiosity on woofer resonance, stored energy and group delay. It looks like I need more 'intel' on these subjects...

Open one door - only to see that the room has 5 more doors!!!!

[tade]

Warning: Large Picture!

http://www.research.philips.com/news...dsp_03-0_h.jpg

I like the B&W monitors used to test their test software! : )

If this is new technology, i am excited. i like new technology!

[timpert]

Hi,

RJ, I made a guess about how they worked, and I definitely agree that more intel is needed. However, you mention you have made a woofer enclosure using a Q of 1.44. In terms of barybass, that might be a tad low, because it only achieves 3 dB extra efficiency at resonance. If you were to take a Qtc of, say, 4 then you would have 12 dB extra efficiency, but only at resonance. Philips claims an increase up to a factor of 10. Would that mean Qtc = 10? Also the impedance would rise to a very high level, meaning that you would indeed need very little power to make an awful lot of racket by exciting it at the exact resonance frequency. The physical part seems to me a driver with relativelty heavy cone, mounted in a small box in order to achieve this high Q and low fs. Rdc is fairly unimportant, because the impedance at resonance will be far greater than it (thinner wire can be used = cheaper) and the dissipated power only minimal. Also the magnet may be fairly weak (again: lower cost).

Up to now, I have described a woofer system that most of us think of as being totally unusable. However, I think that the clever bit lies in this: <start quote>"The key to the success of the BaryBass is that the rest of the low-frequency tones, in this case approximately 20 to 120 Hz, are all mapped onto this single frequency, where efficiency is at a maximum. The frequency range above this is undisturbed."<end of quote> So the trick is in what they call mapping. The URL is another giveaway: part of the url reads syst_softw/dsp. So I am not thinking it will be a single note bass, they are practically admitting it themselves, and they claim to have found a way so that the problem isn't being noticed (by the average joe in the street? Who knows, we'll have to wait for the answer on that.). But still it would be great for portable things like Ipod speakers, laptops, thin TFT screens and other stuff where space is tight. But for serious Hi-Fi? I doubt it.

Jurgen

[RJ]

they claim to have found a way so that the problem isn't being noticed (by the average joe in the street

I agree with you on that point and thanks for the reply.
I get a Qtc of almost 2 with my test setup and almost 6 db gain at 60 hz. I'm just waiting for freinds and family to come hear and get they're opinion on this test setup. I'll betcha they'll like it. I think it has the 60's and 70's style bass sound they used to sell back then. It was done for fun and a learning experience. They do sound good though on some recordings. I think I'll write down the songs that sound good and make a Cd or DVD. Also, I could fix that hump with an Aperiodic vent ala Dynaco.

[sagarverma]

So the trick is in what they call mapping

this is the trick that i suppose can be reproduced by many a learned who throng this great forum.

as mentioned,the 'intel' on this topic is very little on the internet.i found the following

http://www.dse.nl/~rmaarts/

a book about BARYBASS related theory, anyone read the book,share the knowledge.




offrecord::is elf worth building?is its performance good?

[RJ]

anyone read the book,share the knowledge.

Sheesh, at $120.00, at least the pdf at Wiley's bookstore is enough to get enough information as to what is going on.
http://www.wiley.com/WileyCDA/WileyT...470858648.html
Thanks sagarverma for the link. I hope others jump in with their thoughts on this subject.