Can anyone assist me in calculating BL?

[mondogenerator]

I have just finished measuring some t/s parameters using the method described in Weems' book.

I would now like to calculate BL. I have used an equation i found here in another thread but i get an answer which to be at least seems a little off, i get about 2 when the published spec states 5.6. im not sure im using the wrong units or something.

my measured specs are:

Qms 4.750
Qes 0.450
Qts 0.411
Sd 0.0078 m²
Fs 47
Re 5.6
Vas 10.823 litres


Any help or advice would be appreciated. THanks

[mondogenerator]

Originally Posted by mondogenerator

I have just finished measuring some t/s parameters using the method described in Weems' book.

I would now like to calculate BL. I have used an equation i found here in another thread but i get an answer which to be at least seems a little off, i get about 2 when the published spec states 5.6. im not sure im using the wrong units or something.

my measured specs are:

Qms 4.750
Qes 0.450
Qts 0.411
Sd 0.0078 m²
Fs 47
Re 5.6
Vas 10.823 litres


Any help or advice would be appreciated. THanks

can a mod remove this lol i was using litres for Vas and not m³.......silly mistake ....doh!

[stavros]

in my web (sorry in greece)
http://www.speakerlab.gr/papers/parameters.pdf
1. find Cms=Vas/(1.18*345^2*Sd^2*10^8)= 1,25 mmN
2. find Mms=10^6/(Cms*4*3,14^2*Fs^2)= 9,15 gr
3. find BL=[(Re^2*Mms)/(Qes^2*Cms)]^0,25 = 6,30 Tm

[stavros]

1. find Cms=Vas/(1.18*345^2*Sd^2*10^-8)= 1,26 mmN
Sd in cm^2 yours=78 cm^2

2. find Mms=10^6/(Cms*4*3,14^2*Fs^2)= 9,06 gr
3. find BL=[(Re^2*Mms)/(Qes^2*Cms)]^0,25 = 5,77 Tm

stavros

[Gustava]

As a quick and painless solution run Unibox. It provides BL as a product of the driver parameter entry. Also, one of Martin King's Mathcad worksheets includes a BL calculation.

Good luck,
--Steve

[richie00boy]

Were you the guy getting funny readings using Rod Elliot's method? Did you figure out what the problem was?

[PeteMcK]

What Gustava said; Winisd does the calculation too.

[mondogenerator]

Originally Posted by mondogenerator

can a mod remove this lol i was using litres for Vas and not m³.......silly mistake ....doh!

[holdent]

mondogenerator:

Using Martin's T_S_Consistency_Check_Vad worksheet, it generates the following results with your data:

Cms = 1.248 mmN
Mms = 9.192 gm
and
BL = 5.812 newton/amp (or Tm)

I worked through stavros' results by hand and think the difference is simply his rounding off numbers such as Pi. The published spec is quite close to what you've measured.

Martin's worksheets are great and well worth the cost!

[mondogenerator]

Originally Posted by holdent

mondogenerator:

Using Martin's T_S_Consistency_Check_Vad worksheet, it generates the following results with your data:

Cms = 1.248 mmN
Mms = 9.192 gm
and
BL = 5.812 newton/amp (or Tm)

I worked through stavros' results by hand and think the difference is simply his rounding off numbers such as Pi. The published spec is quite close to what you've measured.

Martin's worksheets are great and well worth the cost!

lol its ok thanks...i realised my mistake before anyone replied but couldnt figure out how to delete the post...

I used the equation from an old post on here that someone else wanted for a BL calc, and substitued the numbers into excel..i get 5.787 and i round to about 3dp. its close enough to the 5.6 specified for me to be happy, in fact higher so im a little happier!

thanks anyway rfor you help but i wont be needing MJK's sheets any time soon, as useful as im sure they are. I prefer a pen and paper or just excel lOL