S3100 resonant frequency

[Bernard Wolf]

Hi - I know on the last forum someone answered this question for me but I can no longer find the posting. Does anyone happen to know what the resonant frequency of the 3100 is ? I am planning to use some EQ and do not wish to boost below that frequency.

Many thanks - Bernard

[4313B]

G.T. thought it was in the 30 to 35 Hz range but he couldn't remember for sure. I believe that he recommended not boosting much below 30 Hz. You can measure Fb yourself or have it measured by someone with the necessary equipment. Here is a link that describes several methods JBL recommends - JBL Enclosure Information Manual

[Bernard Wolf]

Thanks Gisgard. I think you are right about the 30-35 hz range as that is what I also seem to recall. I guess I may try to borrow an ocillator and give it a whirl. I am thinking of trying a Marchand Electronics WM8 BASSIS bass correction eq.

Thanks

[Jan Daugaard]

Hi Giskard,

some time ago you provided the T/S parameters for the ME150H as follows:

Fs = 38 Hz
Qms = 6.4
Vas = 130.3 liters
Cms = 0.116 mm/N
Mms = 0.153 kg
Rms = 5.708 mohms
Xmax = ?
Xmech = ?
P-Dia = 337.5 mm
Sd = 0.089 sq.m
Vd = ?
Qes = 0.35
Re = 5.6 ohms
Le = 1.12 mH
Z = 6.72 ohms
BL = 24.2 N/A
Pe = ?
Qts = 0.33
no = 1.969 %
1-W SPL = 95.09 dB
2.83-V SPL = 96.64 dB

I'm still wondering what Rms and Pe are?

[Earl K]

Hi Jan

Hope this helps;

Fs = 38 Hz

I believe you'll find it's more like 28 hz. Since you have a pair . Why not take out one of those brutes and measure Fs for us . Pics would be nice .

Rms and Pe ???

I don't know what Rms might represent .

Pe is power handling in rms watts.

It looks like JBL didn't do a full TS workup. That's likely because the speaker wasn't meant for "over the counter" sales. Reconing appears to be a no-go. Only replacement drivers appear to be avaliable. That sort of makes sense. There may be a huge QC issue at play here. Something more than just dropping a 2235h cone-kit into a 2227h must be at work here. Tinkering with added mass , etc. to get the target weight mms / Fs would be my speculation . Maybe even a rim-ring shim is necessary to centre the coil in the gap - it's all unknown to me .

regards <. Earl K

[4313B]

"I believe you'll find it's more like 28 hz."

One might obtain that Fs after break in, which would also change other parameters. Bottom line - measure the TS parameters of your own drivers after you break them in.

"It looks like JBL didn't do a full TS workup."

This is internal information - it isn't for general public consumption.

"That's likely because the speaker wasn't meant for "over the counter" sales."

You got it

"I'm still wondering what Rms and Pe are?"

Here are some links you can read through -

UNDERSTANDING LOUDSPEAKER DATA

Impedance measurement and Thiele-Small parameters computation

There are many, many other sites you can get information from as well.

[Jan Daugaard]

Hi Earl K,

I downloaded 2 pictures of the ME150H in August 2002, probably from this site, so I don't have to take one of my four S3100 apart to see it.

[Jan Daugaard]

And another picture of the ME150H:

[Earl K]

And up we go !

One might obtain that Fs after break in, which would also change other parameters. Bottom line - measure the TS parameters of your own drivers after you break them in.

I've only broken in 2 of my 4 ME150H woofers. Both settled into an Fs of about 27.5 hz.

And yes, the rest of the TS parameters are in need of some updating .

I might pay someone in the new year to do a pro workup of them .

, Earl K

[Bernard Wolf]

Thanks for that info Earl.... now I know I can boost down to 30 hz. That should save me the need for a sub.


Bernard

[Earl K]

Hi Bernard

You're welcome.

Remember though, the "box tuning" of your S3100 is not likely much lower than 32 or 33 hz ( my guess based on running some tunings ) .


Have you ever "sized" your enclosures to get a "guesstimate" of their internal volume ? FWIW, that enclosure "seems" quite oversized for the unofficial TS parameters .

It seems these newer generation woofers don't mind operating as "under-damped" systems .

regards <. Earl K

[Bernard Wolf]

Hi Earl - well, I'm not much of a "techie" - just like to listen to music ... but with reference to what you just posted, I was lead to believe that the s3100 was overdamped .. what gives ? In any case, as I do now boost occasionaly at 40hz, depending on the music, 32 hz would be real interesting although I will need a different eq as mine bottoms out at 40.

Bernard

[Earl K]

Hi Bernard,

Regarding what I just posted above. It's merely speculation on my part based on running numbers through a software package with suspect TS parameters .

My woofers are operating in @ 2.8 cu' test enclosures - tuned to about 40 hz.

This size, definately gives a very "over-dampened" sound . Very constrained .

That's why I was curious about the internal dimensions for the S3100.
Both you and Jan have spoken very highly of this system .

<. Earl K

[Bernard Wolf]

well then, I will try to figure out the internal dimensions for us all. Let you know.. if I manage that is.. these things are angled as you know so it might take some creative math, at which I am not too good.

B

[Earl K]

Thanks !