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#26 2009-03-17 19:16:35

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>how much excursion are you putting some
>driver though and for how long?

???? ..... I was trying those (Monacors) as 1 foot
OBs with considerable low boost....maybe not all
that much excursion (before gargle) but sometimes
I leave my system run for days.

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#27 2009-03-17 22:04:46

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Innerconflict wrote:

If the Vas # is high, that means the suspension is stiff, right ? If the Fs goes down , then wouldn't that correlate to a looser suspension , or a lower Vas # ?

No, it means it's weak, ergo as Fs goes down it's the suspension (primarily the spider) breaking in (working the starch out), increasing Vas:

Fs = ((1/Pi)/2)*((1000/(Mms*Cms))^0.5)

Vas = 1.43*Sd^2*Cms

where:

Mms is in grams and Cms is in mm/N

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#28 2009-03-18 00:17:17

Nihilist
Knucklehead
From: South Suburbs of Chicago
Registered: 2005-12-09
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Hitsware wrote:

The 2 things that determine Fs are mass and stiffness.
Mass doesn't change but the suspension looses springyness.
Fs is independent of input level.....

I agree, except for the input level. As input levels are increased , temperature levels in the driver increase and parameters change , including Fs. This is not instantaneous , but after a short time of constant input power.

A suspension scenario :

A 10 gram cone is resonant at 50hz with a Vas of 3cu.ft. If the suspension is somehow loosened (Vas # goes down , right ?) , say to 1.5cu.ft. , then the Fs becomes lower ?

Do I have the right idea here ?


I thought I knew what was going on, then people confuse me . . . . .


GM , you posted while I was typing. So what you are saying is the higher the Vas # , the looser the suspension is ? The lower the Vas # , the stiffer the suspension ?






.........................................Blake

Last edited by Innerconflict (2009-03-18 00:21:00)


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#29 2009-03-18 02:44:06

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Correct, so for a given mass, INCREASING compliance (Vas) LOWERS Fs and vice versa.

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#30 2009-03-18 20:34:17

Nihilist
Knucklehead
From: South Suburbs of Chicago
Registered: 2005-12-09
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Driver scenario :

Qts. .38
Fs 20hz
Vas 2 cu.ft.

In a Qb3 alignment, this would yield a box requirement of 2 cu.ft with a tuning of 20hz. (These are approximate numbers.)

Different driver :

Qts. .38
Fs 20hz
Vas 4cu.ft.

In a qb3 alignment , would require a 4 cu.ft. box tuned at 20hz.


This seems somewhat counterintuitive to me. The driver with the "loose" suspension (4cuft) requires a larger box ? Why is this , because the looser suspension's equivalent air volume (4cuft) is larger ? A larger volume of air has less "spring" to it, or basically more area to compress ?


So if we have a tight suspension , it typically requires a "tight" air spring , or in other words a smaller volume of air behind the driver (smaller cabinet )?


Common sense would say that if you had loose suspension , you would want a tight air spring to compensate for the suspensions lack of suspending , or if you had a tight suspension, you would want a looser air spring to compensate for the suspension being so tight.

This concept turns me all around.


And to think I thought I knew what was going on ! ! ! roll


............................Blake


Funny how an Open Baffle can leave some people openly baffled. wink
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#31 2009-03-18 21:41:06

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>So if we have a tight suspension ,
>it typically requires a "tight" air spring ,
>or in other words a smaller volume
> of air behind the driver (smaller cabinet )?

I grock your confusion smile

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#32 2009-03-18 23:35:49

Nihilist
Knucklehead
From: South Suburbs of Chicago
Registered: 2005-12-09
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

"I grock your confusion "

Not sure what that means. Grock was a clown , but I dunno how that fits.Perhaps my confusion amuses you ?





.................................Blake

Last edited by Innerconflict (2009-03-19 00:30:01)


Funny how an Open Baffle can leave some people openly baffled. wink
Pics of CalRad mods
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#33 2009-03-19 00:39:30

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Well, I guess therein lies the crux of the matter, to me it's intuitive........

Yes, all else being equal, for a given alignment, Vb is proportional to Vas.

Right, viewed from an acoustical impedance POV, the driver wants to 'feel' a matching impedance, so one can argue that from the driver's perspective it always wants to 'feel' a Vb = Vas and why I prefer to do so whenever practical.

My common sense says that if there's a stiff spring (low compliance), then a weak one (high compliance) acting on it won't be able to remain linear in excursion unless it has a very powerful force acting on it to offset its high compliance and why a driver with a huge Vas (high compliance suspension) requires a huge Vb if the motor is weak (high Qes) and a tiny Vb if it's strong (low Qes).

IOW, the flattest, most linear speaker system is one where the driver's Vas and effective Qts combined matches the cab's compliance and from this we see that motor strength is the dominant factor in calculating Vb.

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#34 2009-03-19 00:47:23

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Innerconflict wrote:

"I grock your confusion "

Not sure what that means.

Apparently you've never read 'Stranger In A Strange Land' or you would have understood even though he misspelled 'grok': http://dictionary.reference.com/browse/grok?r=75

GM

Last edited by GM (2009-03-19 00:50:59)


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#35 2009-03-19 11:36:05

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>even though he misspelled 'grok'

Groking evedently doesn't demand spelling smile

My intuition is bass ackwards on that also.
Seems the floppier the suspension the smaller
the box. I have learned by rote what's right,
but still have no feel for it.

>Perhaps my confusion amuses you ?

Only in that I share it.
That is why I try to stick with OBs.........
WAY simpler.

Last edited by hitsware (2009-03-19 11:40:21)

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#36 2009-03-19 12:56:36

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

hitsware wrote:

Seems the floppier the suspension the smaller
the box.

This would be true IF you wanted the box compliance to provide ALL damping as is normally the case with a PR, i.e. there is no such thing as a too large a PR Vas spec, only a point of diminishing returns for a given Vb, Fb.

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#37 2009-03-19 19:59:21

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>so one can argue that from the driver's
>perspective it always wants to 'feel' a
>Vb = Vas and why I prefer to do so
>whenever practical.

Yes. That's a simple rule ergo, a good one.
I like Fc = Fs also (or I might mean F3 ?)

anyways -3db spl @ Fs

Last edited by hitsware (2009-03-19 22:33:06)

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#38 2009-03-19 22:22:24

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Yes, Fc or Fb = Fs, though generally not a good plan if driver Qts is > ~0.707 if sealed or ~0.403 for vented.

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#39 2009-03-19 22:47:34

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>Fc or Fb = Fs

c = cabinent
b = box

OR

c = cutoff (-3db) hence F3 ?

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#40 2009-03-20 00:51:13

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Fc = sealed box Fs
Fb = vented box Fs
Fp = pipe (vent or TL) Fs

Where the (-_ dB) point of Fs is a function of the Q of the roll off slope, though Fc = F3 in a T/S max flat sealed alignment and Fb = F3 in a vented alignment when Fs = Fb, Vb = Vas.

F3 = half power (-3 dB) frequency of speaker system response
F6 = quarter power (-6 dB) frequency of speaker system response

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#41 2009-03-20 21:54:43

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>for a given alignment

what does "alignment" mean ?

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#42 2009-03-20 23:24:07

GM
Member
Registered: 2005-07-31

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

?? You know, the speaker's design. Remember, T/S speaker design is based on electrical filter theory, so from an electrical ckt. POV it means the proper adjustment of the various components for coordinated functioning, which is what we do when matching enclosures to drivers, drivers to drivers with XOs, etc..

GM


Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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#43 2009-03-21 20:29:12

hitsware
Moderator
From: Sacramento, Ca.
Registered: 2005-08-06
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

>?? You know, the speaker's design.

O.K.
Why are there ' alignment tables '
for BR and TL but not sealed ?
(BR for sure via Dikensons book ....
If you have the formula, why resort
to tables?

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#44 2009-03-21 21:38:50

planet10
Member
From: Victoria BC NA Sol 3 Milky Way
Registered: 2005-07-28
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

hitsware wrote:

If you have the formula, why resort
to tables?

In the old days when the tables were developed (and usually alighned to "named" filters), you were either doing the calculations by hand or with a slide ruler. Compter SW (and to a lesser extent, calculators) have made the tables an historical artifact.

dave

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#45 2009-03-30 20:29:24

Nihilist
Knucklehead
From: South Suburbs of Chicago
Registered: 2005-12-09
Website

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

Back to the original topic. . .


How about those Betsy K's , Fred ? Any new info ?






..........................Blake


Funny how an Open Baffle can leave some people openly baffled. wink
Pics of CalRad mods
Pics of my SV1000 mods
My Page Of SV and DIY Stereo Links

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#46 2009-03-30 20:45:44

karlsonkab
Member
Registered: 2006-03-21

Re: Wild Burro Audio Labs new USA fullrange 8" speakers

BEtsyK seem really good - in the interest of "break-in" I ran 2 watt 16Hz sine = no problem but my old pc got stuck on a really loud video audio track on top of the 16Hz and popped a tinsel lead loose from one of the cone's eyelets plus one channel of my ancient NAD seems to fail - if I ever run across a spool of solder then will see if B-K can come back to life - in the meantime I built a lopsided interted tapped horn for 15"   _ I don't care if BK hits fs or not as specs even out for alignments and an 8" won't play the bass I like very well

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