[JeffB]

I am curious about essentially the opposite of this thread.
What sized drivers are best for bass?
To avoid confusion, I have no scientific knowledge on which to base opinion and I have no set position on this topic.  
I just have questions.
I also don't have a room where I can place a corner loaded horn, so I have been playing with open baffles and that is where my questions are at.

Ed says,

Using large cone area is always better than excursion for low distortion bass

I have heard it stated elsewhere that large drivers are too heavy and slow and therefore an array of smaller drivers can produce better bass.
However, it seems to me that when building an array of smaller drivers, the drivers would need relatively large excursion relative to their size,
to have a reasonably low Fs.   Unless an array of smaller drivers couples in some manner to either lower the system Fs or increase the normal bass response below the Fs of a single driver.  So, if there is some coupling that I don't know about then maybe a longer excursion is not necessary.
Also semantics play into this, because I think it reasonable that a long throw 8" woofer could have the same excursion as a short throw 15" woofer.
I also can understand that a long throw driver might not produce good highs, because of doppler, but I am not sure that it doesn't mean it can't produce good bass.

If say four 8" woofers can have better bass than a single 15" woofer then this leads one to ask about extremes of this design say
24 3" drivers packed into a grid of say 6 x 4 or even some nano-particle like design using 3600 1/8" drivers.
The driving assumption of this is that the smaller driver has less mms and can be controlled better.
However, I need help understanding how 3600 1/8" drivers might produce 20hz.

I will call the above set of questions, smaller is better.

However, then I have the opposite thought process.
Bigger is better.
Here I am thinking more about midrange than bass.
Feastrex says their 9" inch driver is better than their 5" driver.
PAAudio also says their larger drivers are better.
I was looking at the driver graphs on Zaph Audio's web site.
It seems to my untrained eye that the 6.5" to 7" drivers have lower harmonic distortion than the 5.5" drivers throughout most of the frequency range.
However, the bigger drivers have more trouble reaching a useable cross-over point with standard tweeters.
Most of the designs that I have heard that use smaller drivers as midranges sound closed in and (tin-ee sp?).  Even the arrays of 2" to 4" drivers that I have heard from Athena and Polk just don't seem as open as larger drivers.  I have heard an array of 4 7" drivers that don't sound as good as a single 15".
Perhaps it just comes down to implementation.

So small drivers are better because they are faster.
Big drivers are better because their sound is more open and has less harmonic distortion.
I just don't quite know how to put all these thoughts together.

[Russell Dawkins]

not so complicated a crossover: http://baselaudiolabs.googlepages.com/ADVENT_LA_XO.html

[Ed Schilling]

Jeff,
The relationship between cone area, excursion and acoustic output is one of the basics. And the debate between one big and a lot of small is an old one! I would highly recommend a book like either one of these. I do NOT mean that in a smart ass way. You will learn more stuff much more quickly than searching on the Internet for tidbits.

I could spend page after page on your post! And again I do NOT mean that in a smart ass way and actually that is a good thing.

Try these books..............
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-948
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=500-035

Ed

[Graham Maynard]

Hi Jeff,

Just a quick comment here.

Smaller LF drivers tend to have higher Fs with greater efficiency above that frequency, unless they have heavy cones which make them soak up the power.
For equal LF SPL smaller drivers typically need more boost (cabinet and/or electrical) below Fs and more cut (electrical) at/above Fs; thus there is greater phase change over the working range, and greater difficulty in retaining dynamic accuracy.

Cheers ....... Graham.

[WerTicus]

have you looked at a raven r3?

500hz - 30khz  about as wide range as it gets.

then there is BEengineering's gear similar ranges even better designs though (same designer new company)
Their latest flagship driver is $15k or so    But with DIY the savings over what any design using such a device would cost is huge!  



http://estore.websitepros.com/1736754/Categories.bok?category=ALIAN


Anyhow the speakers i've heard using the older version of this 'driver' were easily the best i've ever heard.
It wasnt a single driver solution but rather the cylinder driver plus two focal drivers for the bass.

I believe there is a DIY version called the 'new york noise maker'
but here is a render of the WAR Audio version:

[Ed Schilling]

Graham,
I left that one wide open for you....please explain how much excursion is reduced or increased if the cone size is doubled or halved (for the same output). I think this is critical for where we are at this minute.

I thought you'd get my hint! But your point is a good one too.

I suggest the books because then you have a handy reference for the basic stuff that might make one grab a calculator.

Ed

[doug s.]

the new york noisemaker was a zalytron kit that used the raven f3 crossed over to two peerless 10" woofers at 800hz.

the alian tweet referenced that goes for $15k each looks like a coax driver.  i like the coax ribbon driver used in the top line piegas - they cross over to mid-woofers at ~550hz...  coax x-over is at 3.5khz.  i have a pair of p5 ltd mkll's that have this driver.  quite nice.     (an unfortunate turn in personal fortunes mean i may have to put these up f/s soon.    )



doug s.

[JeffB]

Thanks Ed,

I don't mind reading a little.
Arg!! but I have so much to read in other areas.
If only the learning process was quicker.

And the debate between one big and a lot of small is an old one!

Ok, but is there a consensus as to which can made to sound better?

[chrisby]

Thanks Ed,

And the debate between one big and a lot of small is an old one!

Ok, but is there a consensus as to which can made to sound better?

definitive consensus in DIY audio?

Ed,  Graham, the floor is yours boys...

let's all play nice now...

[Graham Maynard]

Reading did not get me the audio we have recently appreciated in our lounge, and I'm sure the same applies to others too.

For instance when I see the LF LS in the thumb above provided by WerTicus - internally I go yeough !  I'm so off avoidable monopolar room/building pressurisation (boom-boom) now !

Also there is insufficient correlation between SPL and dynamics to limit the sole usefulness of frequency response curves whether measured or design simulated.

Concensus - No !
Some folk appear to be tolerant of phase change within the reproduced soundwaves, like quantity masking quality, and too many articles or A-B test results are used to prove the relevence of this or that aspect.
How can anyone fully comprehend the strengths and weaknesses of something they have not experienced, for ultimately it could well be the weaknesses which have the greatest impact upon acceptance, no matter how fantastic the strengths !  (No good being the best players in existence if you lose by scoring own goals.)

I am SO fed up with everything needing to be demonstrated in terms of 'flat' SPL, no matter what other contraindications or weaknesses might be being overlooked in order to thus achieve. 
At LF the choice between monopolar-V-dipole, is enclosure volume-V-driver area; sub Fs SPL-V-dynamic clarity;  it just depends what is most important to any indivdual.
(How many 'Hi-Fi' systems can accurately reproduce music which has been recorded live from a stage as opposed to mixed in a studio - does it matter to those who accept the 'sound' superimposed by their own systems and have not heard different types of LS system ?)

My view remains that a single widerange driver gives the best reproduction when compared to typical 2 and 3 ways etc., but that it might be necessary to use as widerange only and then help it at LF and HF if necessary in order to enjoy music at decent listening levels.
Yet even with dipoles and U/H frames which store negligible energy, an indicated flat SPL characteristic still cannot indicate by how much eventual acoustic music transduction has become group delay distorted due to the different predominances between driver/crossover characteristics around say 200Hz.

Hi Ed. 

Re the LF - it is unavoidable energy storage mechanisms like cone mass, enclosure air spring and tuned volumes which I seek to avoid because these all take additional energy from a first half cycle and return it later at some different non-musical resonant frequency which intermodulates reproduction.
Re driver size - smaller drivers frequency double at higher frequencies, ie. you can often hear output of near inaudible 20Hz through an 8" driver but not from an 18" when both are generating the same displacement with equal efficiency.  Someone might conclude the SPL generated by the 8" is better !!!


Cheers ......... Graham.

[Ed Schilling]

http://www.stereophile.com/reference/1104red/

Some light reading..............

Graham, Agreed on the reading thing....sort of.....nothing beats experience but for reference nothing beats written down stuff!

I think it important to learn the basics. Books are good for that....much better than the Internets I think.

The point you make about the 8" driver is scary! It never occurred to me people could be so easily fooled.

You wrote:
"My view remains that a single widerange driver gives the best reproduction when compared to typical 2 and 3 ways etc., but that it might be necessary to use as widerange only and then help it at LF and HF if necessary in order to enjoy music at decent listening levels."

And there you go...........EXACTLY what sent me on the 10 year quest that resulted in my favorite speaker. And I think by now we all know how I "solved" that for me. And  WAY too many don't understand the point you just made. But that is NOT the point of this thread! However I am glad you made it. ZU gets it. If you can make a 3 way behave as a single driver but yet play at levels a large format single driver can't dream of, I'd say the 3 way (or 2 way with sub)  is a better speaker. Especially when we are talking about LARGE single driver speaker cabinets.....A big speaker that can't play loudly is not a good thing...even if it is a single driver. Why bother?

But lets keep asking questions......how about this.....people claim all the time they can "hear differences in wire".....if that is so doesn't it make sense that a cone flopping back and forth might be a source of audible distortion if it is also making "treble" at the same time?

Wouldn't deliberately limiting this excursion (low bass) result in a cleaner sound from the single driver? And why would this be a problem when a dedicated sub would be much better at making it anyway?

So, do we really want or need a 10 gram 6 inch tweeter trying to make bass as if it were in a 2 way?

Ed

[Graham Maynard]

but for reference nothing beats written down stuff!  I think it important to learn the basics. Books are good for that....much better than the Internets I think.

The point you make about the 8" driver is scary! It never occurred to me people could be so easily fooled.

Ed - we've all been fooled - initially the books did this - some who were fooled (taught to understand in a specific way) still perpetuate the 'book blinkered' view !  (I'm not saying that the books are wrong, just that minds focus on what is read, and thinking beyond a well reasoned authoritative text becomes difficult.  So often it is the application of theory which is inadequate, not the theory itself.)

Near everything is based on sines;  more recently there have been impulse based transforms, neither of which look at complex dynamic interactions during music time.
This being where cable differences become audible whilst not showing significant measurable steady sine or impulse difference, and why I use LS sited voltage output monoblocs with low impedance signal feeder drive to prevent cable losses.
Current drive and high Q LF drivers increase dynamically induced amplitude distortion, which might or might not be desireable depending upon bandwidth.

Gilbert Briggs showed the frequency doubling with 8"ers compared to 12"ers 50 years ago, commenting that the unexpectedly high output when driven with constant input below 50Hz was not pure. 
More recently Decware have shown how the LF output of the Fostex FE206 can be cleaned up, see 2/3 down;-
http://www.decware.com/paper79.htm.
Hence the Fostex would output more LF than the Decware on an OB - depends what we want !

Even the Visaton B200 I use distorts harmonically at LF, this being the main reason it 'sounds' good to listen to alone on a large OB - it fills out the LF reproduction with euphonic distortion - but the acoustic waveform is no longer like the recorded electrical waveform.


Cheers ........ Graham.

[Graham Maynard]

... doesn't it make sense that a cone flopping back and forth might be a source of audible distortion if it is also making "treble" at the same time?

Rewrite -

... doesn't it make sense that a cone flopping back and forth might be a source of audible distortion if *different parts of the same cone are* also making "treble" at the same time *but out of time with each other too* ?

and it is keeping LF out of the widerange which is our defence against scoring these own goals; ditto keeping sub frequencies out of mid-bass drivers !
also defending against losing the game due to treble which is made at the same time by different parts of our 10 gram, 6" tweeter cone  !

Lynn Olsen's aim with his OB project also applies the logic of increasing cone area with decreasing LF.  He proposes the use of different Q as well as different sized LF drivers, which again will affect group delay relationships within and between individual driver bandwidth ranges, yet could still be useful at lowest frequencies.

Cheers ......... Graham.

Ed.  Any chance of a hyperlink to your current loudspeaker project if uploaded anywhere ?

[Ed Schilling]

Just a quick one.....
I stumbled on this and it happens to be in the same area where we are  now, .....and I could not agree more on this..... I have said the same thing a zillion times. Nice to see someone who is not an idiot (like me) say it. I hope it's OK how I am using this quote.

My own experience is that excursion-limited distortion plays a large role, and getting bass extension at the price of excursion limitations is not a good tradeoff.


Here is the place and the quote is from Mr Joppa's post.   http://www.audioasylum.com/cgi/vt.mpl?f=hug&m=136611

Now don't get me wrong he is exactly right as far as I am concerned, now, figure out why someone (like me, and countless others, for instance) would knowingly build something that does use extreme excursion to "make bass"? And they obviously "work"....so what's the deal?

How does this apply to single driver speakers.....and it does, BTW.

Just questions to ponder..................

Ed

[Graham Maynard]

Subs have low bandwidth and don't carry the harmonics we recognise as musical intonation.  You can distort and clip sub output, but if the upper bass remains cleanly reproduced by another driver or widerange/tweeter, then you do not notice.

However having upper bass riding on the back of wideband cone excursion does modify harmonic relationships is most noticeable.

The questions are whether to augment and how - aperiodic, dipole types, horn, line and tuned types - whereupon the widerange can still command the musical performance if its clean output range (recognisable harmonics) extends down to upper bass frequencies.

Cheers ....... Graham.

[DanTheMan]

So the case against a 10gram 6 inch tweeter basically looks like this:  break-up and beaming?

For such a thing used as a FRer:  limited volume and depth of distorted bass combuned with unequal power response?

Does that sum it up in layman's terms or was there even more?

thanks,

Dan

[Graham Maynard]

And yet both break up and beaming (which also exacerbate the FR rising response with frequency) can be reduced by foam in front of the cone, such that a 10 gram, 6 inch tweeter can still be pleasantly useful.

Cheers ....... Graham.

[Ed Schilling]

Graham....a little poke at you ( )...... yea,  you can do all kinds of things to make a driver "do stuff it shouldn't",  like for instance,  add mass to a cone in order to raise QTS and lower Fs at the same time with a sensitivity penalty (and therefore a lowering of power handling)....but is it a good idea?
?
?
?
?

Yea, works fine.....used the technique  with good effect many times....and often wondered why it's not more common given it's effectiveness.

Ed
(I sure hope some of you speaker builders out there are getting any of the good hints sprinkled all through this thread)

[Graham Maynard]

Graham....a little poke at you ( )...... yea,  you can do all kinds of things to make a driver "do stuff it shouldn't",  like for instance,  add mass to a cone in order to raise QTS and lower Fs at the same time with a sensitivity penalty (and therefore a lowering of power handling)....but is it a good idea?

Squeak !

Given that I am writing in the single driver (full range type) category the only alternative is electrically limiting the range/output of the main driver and using others to augment output.

I suspect you are writing about adding mass to drivers for LF only, and when you do that you often end up needing to either pad the main driver or separately amplify the LF one, which is somewhat removed again.

Clearly we would not have a tweeter or even a good FR/WR driver if mass were added to it.

Long ago I found it best to counter the beaming on a WR driver using air side felt/foam (no series R, or crossover other than to bandwidth limit if required) and blend in augmentation using light cone larger driver(s) for LF. 
I also found (because I have tried) that heavier cone, higher impedance, or air-mass tuning of drivers all made for dynamically impaired or audibly detached (slow) bass with poor bass/mid integration.  I too tried adding mass to an already existing cone/suspension and felt it was a botch-up which did nothing right.

The most important thing at LF is cone acceleration/excursion, and adding mass immediatly reduces the dynamic capabilities for any given power drive.

So, adding mass is not a good idea amongst my read only memories - buy the right driver and do the job properly.

Cheers ........ Graham.

[Ed Schilling]

Graham,
Actually it has been used to very good effect on the 1197 by John Cockcroft in his "Simpline". Published in Speaker Builder.
I built several pairs as Christmas gifts many years ago. They sounded excellent but of course were very inefficient and had limited output. Not unlike many single driver systems built using inefficient drivers to start with. Most of those speakers are still being used every day!

I'm fighting a virus on my network now....but I can scan the article later if anyone cares.

The technique while not a "good idea" has been shown to "work". Quite well in that design I should add.

But really I agree with your post on most every level.....

Clearly we would not have a tweeter or even a good FR/WR driver if mass were added to it.

And that statement right there sums up my opinion of a FR driver with a high mass to start with! And that said, the Simpline defies that very notion. What's a guy to think?

One can build the Simplines for about 30-40 bucks in about 2 hours to test the concept...they may be the best balanced single driver speaker they have heard. They really are very good.....but only for small rooms and moderate SPL's. The Fostex 103 will work perfectly in place of the 1197. It should since they are "the same".

Ed