BassBox Pro, prototype ?

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REALFLEO

Member
Joined 2006
Hi all,

I just download BassBox Pro 6.0.18.

I was wondering if I need to build a 20% bigger prototype and ajust his volume with solid filler after, as suggested in Loudspeaker design Cookbook... ? Or should I trust BassBox and just built it as they are saying ?

I'm building a vented loudspeaker.

What do you guys think about this software ?

Thanks a lot,

REALFLEO
 
R

REALFLEO

Member
Joined 2006
Wait they are saying to make it bigger for a prototype and decrease the size with solid filler later during the tunning phase.

Just because, according to Loudspeaker Desing Cookbook, it is not unusual for losses to be lower than 7.

Thanks for the reply,

REALFLEO
 
S

sreten

R.I.P.
Joined 2003
REALFLEO said:
Wait they are saying to make it bigger for a prototype and decrease the size with solid filler later during the tunning phase.

Just because, according to Loudspeaker Desing Cookbook, it is not unusual for losses to be lower than 7.

Thanks for the reply,

REALFLEO
Click to expand...

Hi,

Yes and its still a stupid idea, because the LDC is a stupid book.
Reducing cabinet volume in most vented alignments is pointless.

:)/sreten.
 
Ron E

Ron E

Member
Joined 2002
REALFLEO said:
I was just looking for a method to ajust box losses in case it's different then 7.
Click to expand...

There is a lot of good beginener level info in the LDC. The author is knowledgeable, but the book is not targeted at advanced amateurs.

IMO the biggest disservice his book does in box design is to focus too much on alignments and make it seem like if your box is not exactly on target it will not sound good. I appreciate his nicely calculated tables and such, but they only serve as starting points, and these alignments actually only exist if the model is simplified to a substantial degree. For more complex box models, there is no such thing as QB3, C4, BB4 and all that nonsense.

Absolutely fantastic vented boxes can be made with the simple rule:
Fb=0.42*Qts^-0.96
Vb=20*Vas*Qts^3.3
...and to be honest it makes just as good a starting point as the tables in the LDC.
 
v-bro

v-bro

Member
Joined 2006
Hi,

exactly, I've seen designs (like vifa 'impuls' and vifa ....I believe it was called 'filigran'?) both shared the same bassmid and tweeter (17WP200 with HT-300D/2) but the one had half the cabinet volume of the other (both ported designs).:rolleyes:

Most commercial loudspeakers were chosen from many similarly designed cabinets (say same volume but different shape...).

Thing is the shape does more to the sound than the volume (volume should be 'aproximately right' as it deals with the 'anti-sound' (radiated from the rear of a driver) which is 'produced' inside the enclosure). The shape influences the front radiated sound (the sound you're supposed to hear...) and it influences it a lot! :)
 
S

sreten

R.I.P.
Joined 2003
Ron E said:


There is a lot of good beginener level info in the LDC.
The author is knowledgeable, but the book is not targeted at advanced amateurs.
Click to expand...

Hi,

TBH I've never read it. But I've read far too many posts from
"beginners"who think they know what they are doing due to
this book, especially crossover design when in fact they have
got no idea of what is actually going on.

The worst louspeaker designers in the world are "electrical
engineers" armed with text book electrical theory, (I should
know, I have a degree in the subject), simply because they
think if anyone understands whats going on it is them.

Miixing up basic electrical theory and filter theory with designing
speakers is a recipe for misinformation and misunderstanding.

:)/sreten.
 
Svante

Svante

Member
Joined 2004
Ron E said:


IMO the biggest disservice his book does in box design is to focus too much on alignments and make it seem like if your box is not exactly on target it will not sound good. I appreciate his nicely calculated tables and such, but they only serve as starting points, and these alignments actually only exist if the model is simplified to a substantial degree. For more complex box models, there is no such thing as QB3, C4, BB4 and all that nonsense.
Click to expand...

Boy it feels good to read this. I repeatedly try to tell people thaqt these equations are not an ultimate goal, but just something that gives a starting point.

Yet, the equations seem to have a great attraction factor to the newcomer, maybe it is because equations seem so exact?

You are smart guys, RonE and Streten!
 
richie00boy

richie00boy

Member
Joined 2003
readresearch.co.uk
Ron E said:
Absolutely fantastic vented boxes can be made with the simple rule:
Fb=0.42*Qts^-0.96
Vb=20*Vas*Qts^3.3
...and to be honest it makes just as good a starting point as the tables in the LDC.
Click to expand...

Bit hazy now, but is that from one of the Weems books?

sreten said:
TBH I've never read it. But I've read far too many posts from
"beginners"who think they know what they are doing due to
this book, especially crossover design when in fact they have
got no idea of what is actually going on.

The worst louspeaker designers in the world are "electrical
engineers" armed with text book electrical theory, (I should
know, I have a degree in the subject), simply because they
think if anyone understands whats going on it is them.

Miixing up basic electrical theory and filter theory with designing
speakers is a recipe for misinformation and misunderstanding.

:)/sreten.
Click to expand...

I totally agree with you about neglecting acoustic responses. I'm an EE myself, but please don't lump us all in the same basket ;)

I suggest you read the LDC before you slag it off, it does actually cover taking the acoustic responses into account. It's just further into the section and most beginners seem to just glimpse at the beginning...
 
Svante

Svante

Member
Joined 2004
richie00boy said:


Bit hazy now, but is that from one of the Weems books?
Click to expand...

As far as I understand, these equations originate from a paper by Margolis/Small (which I don't have at hand right now).

Edit: I found it, it was in a JASA article from 1981: Personal calculator programs for approximate vented-box and closed-box loudspeaker system design, JASA vol 29 no 6 1981 june p 421

The article is written at a time when calculators were frequently used for designing loudspeakers. The simplistic natrure of these formulas were great back then, but nowadays when computers are available they have more or less served their purpose. At best, the give an initial suggestion on where to start.
 
Svante

Svante

Member
Joined 2004
sreten said:

Miixing up basic electrical theory and filter theory with designing
speakers is a recipe for misinformation and misunderstanding.

:)/sreten.
Click to expand...

Haha, I missed that one. I would say that electrical theory and filter theory are essential to understanding loudspeakers. It is just that one needs to understand acoustics as well.

But maybe that was what you meant?
 
S

sreten

R.I.P.
Joined 2003
Svante said:


Haha, I missed that one. I would say that electrical theory and filter theory are essential to understanding loudspeakers. It is just that one needs to understand acoustics as well.

But maybe that was what you meant?
Click to expand...


Hi,

I meant it is best not to mix basic (electrical theory and filter theory)
and loudspeaker design in a book, it all gets horribly confusing, and
nearly every beginner gets the wrong end of the stick in understanding.

Glossing over the acoustics and expounding innapropriate basic
theory is typical, is what I meant, I find it extremely frustrating.

Take a look at Speaker Workshop's guide to designing crossovers ......

:)/sreten.

P.S. rb - only lumping EEE's who only know textbook electrical theory together.
 
R

REALFLEO

Member
Joined 2006
Nice to have opinion of experimented persons about LDC and audio in general. I love Internet. Without this forum, LDC would prolly be my bible ...

Sreten, these are params of my protoype:

Q params I mesured myself:
Qes=0.46
Qms=3.125
Qts=0.4

Vifa's Q params:
Qes=0.4
Qms=2.46
Qts=0.34

I used my Q params to calculated Box volume:
Vb:21.542lts
Fb:40.1713
F3:40.6007
Lp:41.6768
Dp:3inch

To this volume, I added 4.3084lts(20%) and 1.50305lts(port volume)

and now when I calculated Ql and I obtained -0.12 ...

Thanks a lots guys,

REALFLEO
 
S

sreten

R.I.P.
Joined 2003
Hi,

Please add Vas and Fs of your driver, and Vas and Fs of specs.

Note for a typical driver in a typical box, if Fs is higher, Vas lower and
consequently Qts somewhat higher than manafacturers specification,
it doesn't really matter too much as long as Vbox < ~ 0.5 Vas.

:)/sreten.
 
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