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Old 23rd May 2014, 08:59 PM   #11
mrneedle is offline mrneedle  Netherlands
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Thanx for the reply's!

but I might just be a bit to new at this, don't have a clue what you guys (Scottmoose, GM) are chatting about. I'll see if I can figure it out and then I'll probably have some more questions
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Old 23rd May 2014, 09:53 PM   #12
GM is offline GM  United States
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You're welcome!

Unless you're interested in learning speaker design at an advanced level you can ignore our 'techobabble'. His design is listed in MJK 'speak':

GM
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File Type: pdf Box_App_Notes.pdf (7.5 KB, 94 views)
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Old 25th May 2014, 10:43 PM   #13
mrneedle is offline mrneedle  Netherlands
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Quote:
Originally Posted by Scottmoose View Post
Since nobody seems to have offered anything, here's an MLTL tuned for some gain through the midbass region.

L = 35in
CSA = 88.5625in^2
Zd = 7in
Vent 13in^2 at the bottom
Stuff 0.75lbs ft^3 & adjust as desired.
Ok being from the metric system a friend and me tried to 'translate' these numbers..

am I correct:

L=Lenght=88,9cm
CSA=?=571,36983cm2 (seen the cab from the top about 20x25cm?)
Zd=?=17,78cm
Vent=Vent=83,8708cm2 (about 9x9cm?)

if i'm right this seems to be bit large... at least large for what i'm used to have in the living room.
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Old 25th May 2014, 11:42 PM   #14
GM is offline GM  United States
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Yes, except of course the 20x25 and 9x9 are too small.

The stuffing density: 0.75lbs ft^3 = 340.1943 gr/0.02831685 m^3

FWIW, I've been using this little program since it came out with nary a mistake [when I input the right numbers of course!]: Convert for Windows - joshmadison.com

Right, and as I noted, why I didn’t bother to post my much bigger one. Bottom line, driver specs dictate the size required for a driver to reproduce ‘x’ amount of bass at ‘y’ tuning [Fb], so the more you shrink the cab, the less bass you have. Factor in that tiny drivers need all the acoustic gain one can afford in size just to get any real bass, it can be all out of proportion to the driver size; which of course makes sense as the larger the driver, the more air it can move for a given power.

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Old 26th May 2014, 09:14 AM   #15
mrneedle is offline mrneedle  Netherlands
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In dutch we have an expression which translates best as rocking the boat but if you would translate it directly it would be "swearing in the church"

Dont want to get off topic but...:

Could one keep the cab smaller while using some kind of filter to push up the lower freqs?

How do those hifi manufacturers make those very sensitive small speaker cabs which blow you away (with to much bass)?
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Old 26th May 2014, 10:28 AM   #16
Scottmoose is offline Scottmoose  United Kingdom
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Quote:
Originally Posted by GM View Post
FWIW, I've been using this little program since it came out with nary a mistake [when I input the right numbers of course!]: Convert for Windows - joshmadison.com
+1 -probably from your tip. Great little program.

Quote:
Could one keep the cab smaller while using some kind of filter to push up the lower freqs?
You could use a very small sealed box & Eq it (preferably digitally). Power handling will be crippled, but it's not impossible providing you listen quietly on undemanding material (i.e. with little LF dynamic range).

Quote:
How do those hifi manufacturers make those very sensitive small speaker cabs which blow you away (with to much bass)?
They can't and don't. They are obliged to operate within the laws of physics, same as the rest of us. Hoffman's iron law: pick any two of these. You can't have all three:

-Small size
-High efficiency
-Low frequency extension

Some might deliberately engineer in a peak at Fb to give the impression of more bass than is actually the case. Not a good idea.
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Old 26th May 2014, 04:13 PM   #17
IG81 is offline IG81  Canada
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Quote:
Originally Posted by mrneedle View Post
How do those hifi manufacturers make those very sensitive small speaker cabs which blow you away (with to much bass)?
As said above, they don't. My guess is the sensitivity parameter usually takes a hit since most people would not see a need for it, at least compared to size and bass extension which will weigh-in heavily.
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Old 26th May 2014, 06:48 PM   #18
chrisb is offline chrisb
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IINM, Mr Hoffman's observation was based in the very early days of the "acoustic suspension" (much smaller simple sealed enclosures and often woofer dimensions than previously) revolution that was enabled by the advent (so to speak) of affordable higher powered SS amps with high damping factors and excellent sonics

well - if you remember the big SS amps of the late 60s early 70s, 2 / 3 ain't bad (Crown DC300, BGW 750 anyone? - no? )

so in other words, unless you're married to tube amps in the single digit or low teens power level, sensitivity is often less of an issue than enclosure volume and driver excursion limits - sure with enough horsepower you can EQ a 4" driver down to sub30Hz without clipping the amp, but not without substantial risk to the driver
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Last edited by chrisb; 26th May 2014 at 06:52 PM.
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Old 29th May 2014, 01:52 PM   #19
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by mrneedle View Post
Could one keep the cab smaller while using some kind of filter to push up the lower freqs?

How do those hifi manufacturers make those very sensitive small speaker cabs which blow you away (with to much bass)?
It's called a Linkwitz transform (LT). When to use in a sealed speaker high Q? It's needed when the speaker is too small and Q>1. You need an extra power amp and a LT circuit, as was mentioned.
Links e.g., Linkwitz Transform Subwoofer Equaliser
http://www.diyaudio.com/forums/multi...ml#post3943704
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Old 5th June 2014, 06:55 AM   #20
ttan98 is offline ttan98  Australia
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Default Freq. Response of Chinese 5in Full Ranger

Hi,
As promised earlier find attached the freq. response of my newly acquired Full Range 5" driver. The images are self explanatory.
The peak at 4Khz maybe a little worrying and comments anyone. Otherwise it seems quite good, the spl is about 89-90db, compared it against GR Research M130 which I know is easy to drive has about 89dB.
Looking forward to use them in a 2way speakers, with a helper woofer.
Attached Images
File Type: jpg Chinese 5in&M130.JPG (249.2 KB, 404 views)
File Type: jpg Chinese 5in FRdirectivity.JPG (250.4 KB, 398 views)

Last edited by ttan98; 5th June 2014 at 06:59 AM. Reason: re-writing the title
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