ScanSpeak 8530

[GringoAudio]

I just acquired a pair of these Scan-Speak 8530 mid-woofers along with a pair of 2905/9500 tweeters. The T/S parmeters given byt he ccompany on the current website are very different than those given by NothCreek Audio. They have used and tested many over the years. But the numbers are S different I am worried about which ones to use or to even use as a rough guideline.

[Notax]

Originally posted by GringoAudio
I just acquired a pair of these Scan-Speak 8530 mid-woofers along with a pair of 2905/9500 tweeters. The T/S parmeters given byt he ccompany on the current website are very different than those given by NothCreek Audio. They have used and tested many over the years. But the numbers are S different I am worried about which ones to use or to even use as a rough guideline.

Put both versions here.

There is 2 versions of 15W/8530:

15W/8530-k00 (magnet 110 mm)

15W/8530-k01 (magnet 90 mm)

Thay have different BL because of magnet. That means different Qes, Qts.

[GringoAudio]

Hi again,
I understand there are two versions. Thank you for that though. I have the 15W/8530K-00. The parameters given by Scan-Speak are an Fs of 30 Hz vrs. 36 Hz from North Creek Audio. The Qts is given as .27 by Scan-Speak vrs. .40 from NorthCreek. The Vas is given as 28 litres by Scan-Speak and is 16 litres as measured in multiple samples by NorthCreek. What gives? Are all T/S parameters so untrustworthy?

[Notax]

Originally posted by GringoAudio
Hi again,
I understand there are two versions. Thank you for that though. I have the 15W/8530K-00. The parameters given by Scan-Speak are an Fs of 30 Hz vrs. 36 Hz from North Creek Audio. The Qts is given as .27 by Scan-Speak vrs. .40 from NorthCreek. The Vas is given as 28 litres by Scan-Speak and is 16 litres as measured in multiple samples by NorthCreek. What gives? Are all T/S parameters so untrustworthy?

Its little bit strange so big differecies. There is from series to series, but it would be smaller. Second, you just must to measure units you got. Its the best way for real TS parameters. Of course, after you breaking in really good unit at resonant frequency few days.
Anyway, all that differecies are from different Cms. So you got different Fs, Qms, Qes, Qts, Vas. Its maybe a strange but that dont influecne at Vb an Fb so much.

For example SS 15W/8530K-00: 1. first Cms=2,165 mm/N
2. Cms=1,281 mm/N, all other relvant parameters the same.Relvant are: Sd, Mms, Re, BL, Rms which produce every other as: Qms, Qes, Qts, SPL (the same, Cms dont inffluence at SPL).

1.Cms=2,165 mm/N

Fs=30 Hz
Mms=13 gr
Sd=95 cm2
Rms=0,5 kg/s
BL=7 N/A
Re=5,8 Ohm

SPL=86 dB
Qms=4,9
Qes=0,29
Qts=0,27
Vas=27,3 L

With standard simulations the best is about 9,6 L and Fb=44 Hz.

2. Cms=1,281 mm/N

Fs=39 Hz
all from first group the same: Mms, Sd, Rms, BL, Re

SPL - same
Qms=6,37
Qes=0,377
Qts=0,356
Vas=16,15 L

With standard simulations you got almost the same as before. Little bit higher Vb=10,2 L and Fb=45 Hz.

Got it?

[GringoAudio]

This is a unit I do not know. Please explain what the two examples with two different Cms means. Thanks.
Greg

[MBK]

There was a post from a Seas engineer some time ago about T/S measurements. Typically measurements are done at line levels (say 100 mV). According to this engineer though, the suspension measures quite differently under average load voltages, say 1 to several Volts. And this is where Cms comes in (mechanical compliance, as in, rubber stiffness of the surround etc AFAIK).

In other words results can easily depend on the measurement conditions and SS themselves may actually have a better estimate on this, knowing their drivers, their average break in periods and therefore the voltage levels to use for measurement. The measurements of a retailer are likely made with a one size fits all setup.

[Notax]

Originally posted by GringoAudio
This is a unit I do not know. Please explain what the two examples with two different Cms means. Thanks.
Greg

Cms is a stiffness of the moving system, and it is not static.
3 relations are conected. Cms, Fs and Mms (mass of moving system).

Fs=1/2*Pi*sqr(Cms*Mms)

Cms (m/N)
Mms (kg)
Fs (1/s)

Two examples are (if you wish, virtualy) the same unit - Scan-Speak 15/W8530K-00 with different Cms which influence at different values of: Fs, Qms, Qes, Qts, Vas but did not influence at SPL, and when you calculate you can see it dont influence at enclosure volume (Vb) and tuning frequency (Fb).

[Notax]

Originally posted by MBK
There was a post from a Seas engineer some time ago about T/S measurements. Typically measurements are done at line levels (say 100 mV). According to this engineer though, the suspension measures quite differently under average load voltages, say 1 to several Volts. And this is where Cms comes in (mechanical compliance, as in, rubber stiffness of the surround etc AFAIK).

In other words results can easily depend on the measurement conditions and SS themselves may actually have a better estimate on this, knowing their drivers, their average break in periods and therefore the voltage levels to use for measurement. The measurements of a retailer are likely made with a one size fits all setup.

That is right.

For all. Check this.

http://members.fortunecity.com/pirim...Impedance.html

and hole tread : Calculations of bass-reflex enclosures - generally !!!

[GringoAudio]

nt

[Notax]

Originally posted by Notax
[B]





and hole tread :

whole

I am shure my bad English can be funny sometimes.