Confusion has occupied my head!

sobazz · 22nd January 2004, 09:23 PM

D***... I downloaded Speaker Workshop today. Normally I model drivers in WinISD, but SW is a more comprehensive solution and I'm about to measure response on some small speakers I've made, for which SW seems brilliant.

In order to get to know the program I entered the data for the midbass driver used, a Vifa TC11SG, and modeled the frequency response with the same enclosure and port data.

But the response computed by SW is very different from WinISDs. Instead of an almost flat response around 70hz I got a 5db peak at 80hz! Why?

I've confirmed the parametres several times, but they are exactly the same as the ones used in WinISD.

SY · 22nd January 2004, 09:33 PM

Is there a difference in the assumed box loss parameter (Q_L)?

sobazz · 22nd January 2004, 09:57 PM

No. I changed that the WinISD values too. By the way... it has suddenly changed to the worse... now I have a peak of 8db at 145hz and a rolloff below 0db from 115hz... I cannot see what I've done!?

WinISD first:

sobazz · 22nd January 2004, 10:03 PM

Ehh.. sorry about the freq. response range.

Here's SW

sreten · 22nd January 2004, 10:07 PM

Sad but true, freeware is not always accurate,
they don't have to be.

I don't know the answer to this but;

the secret to using freeware is what it does right.

All freeware is extremely limited compared to the
professional products, simply thats the way it it is.

WinISD is simplistic but AFAIK never too far wrong.
SW claims a lot more than it can deliver, IMO.

sreten.

sobazz · 22nd January 2004, 10:13 PM

Huh.. I thought the formulars used were pretty standard formulars for calculating speaker response with T/S.... Arghh...

sobazz · 22nd January 2004, 10:16 PM

Another reason why I dislike Speaker Workshop: it's interface is extraordinarily inefficient...

sreten · 22nd January 2004, 10:24 PM

A port length of ~ 6" and ~ 2.8 " diameter is not for an 1/8 cuft box.

you may have your radii and diameters confused.

sreten.

sobazz · 22nd January 2004, 10:31 PM

No way. 6" = 150mm is ok. The same in WinISD for Fb = 68hz. The port diamter is 1.378" (and not what you wrote) = 35mm. The box volume 1/8 ft^3 = 3.5L.

All of the above is perfectly ok.

officeboy · 22nd January 2004, 10:39 PM

Quote:

Originally posted by sobazz
No way. 6" = 150mm is ok. The same in WinISD for Fb = 68hz. The port diamter is 1.378" (and not what you wrote) = 35mm. The box volume 1/8 ft^3 = 3.5L.

All of the above is perfectly ok.

no, in Speaker workshop, the port RADIUS is 1.378"

22nd January 2004, 09:23 PM	#1
sobazz diyAudio Member Join Date: Apr 2003 Location: Jutland	Confusion has occupied my head! D***... I downloaded Speaker Workshop today. Normally I model drivers in WinISD, but SW is a more comprehensive solution and I'm about to measure response on some small speakers I've made, for which SW seems brilliant. In order to get to know the program I entered the data for the midbass driver used, a Vifa TC11SG, and modeled the frequency response with the same enclosure and port data. But the response computed by SW is very different from WinISDs. Instead of an almost flat response around 70hz I got a 5db peak at 80hz! Why? I've confirmed the parametres several times, but they are exactly the same as the ones used in WinISD.

22nd January 2004, 09:33 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Is there a difference in the assumed box loss parameter (Q_L)? __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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22nd January 2004, 10:07 PM	#5
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Sad but true, freeware is not always accurate, they don't have to be. I don't know the answer to this but; the secret to using freeware is what it does right. All freeware is extremely limited compared to the professional products, simply thats the way it it is. WinISD is simplistic but AFAIK never too far wrong. SW claims a lot more than it can deliver, IMO. sreten.

22nd January 2004, 10:13 PM	#6
sobazz diyAudio Member Join Date: Apr 2003 Location: Jutland	Huh.. I thought the formulars used were pretty standard formulars for calculating speaker response with T/S.... Arghh...

22nd January 2004, 10:16 PM	#7
sobazz diyAudio Member Join Date: Apr 2003 Location: Jutland	Another reason why I dislike Speaker Workshop: it's interface is extraordinarily inefficient...

22nd January 2004, 10:24 PM	#8
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	A port length of ~ 6" and ~ 2.8 " diameter is not for an 1/8 cuft box. you may have your radii and diameters confused. sreten.

22nd January 2004, 10:31 PM	#9
sobazz diyAudio Member Join Date: Apr 2003 Location: Jutland	No way. 6" = 150mm is ok. The same in WinISD for Fb = 68hz. The port diamter is 1.378" (and not what you wrote) = 35mm. The box volume 1/8 ft^3 = 3.5L. All of the above is perfectly ok.

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