Double bass reflex information

[Ilianh]

I've been searching for weeks now for any information on double bass reflex boxes, projects, theory.

I just could not find enough information to even start a project.

I suggest we make a collection of information sources, experiences and share projects in this thread.

Any books recomendations? articles?

Heres what I could find.
- http://www.quarter-wave.com/Models/MathCad_Models.html
Wonderfull mathcad worksheets for DBR simulation from Mr. King.

- http://www.geocities.com/fuherb/168dbr.htm
An interesting project with fe168

- http://www.fostexspeaker.de/gehaeuse/83e_enclrev.pdf
fostex recomended DBR for fe83

Thanks!

N.B, I speak here of DBR configuration, excluding all Nth order band pass boxes.

[kelticwizard]

Well, here is a link to a thread about the Double Bass Reflex, but a different configuration and different response pattern.
article about double chamber speaker enclosure

LspCAD models the type you mentioned, and you can download a free demo made for Adrie only-the Shiva, the AV8, etc.

[REDSKIN]

just to make sure that I'm thinking along the right lines. We're talking about taking a ported alignment then splitting the internal volume 2:1 and then joining the 2 created chambers with each other and the outside world using 3 identical ports? Is that about right?

The advantages being what? That you can control cone motion over a wider range than with a normal ported box? That you can get the sound of a sealed with the extra efficency of a ported design, or are there other advantages?

This seems to be a win win design but are there any short commings?

[REDSKIN]

DOH! IT would help if I read the links before commenting. Sorry for stating the obvious. More thought before posting me thinks.

[Lusso5]

Good info here with calcs.

[kelticwizard]

As long as Ilianh understands that the fostex enclosure is a different kind of enclosure from the other kind of Double Chamber Reflex with a different response entirely.

[macky888]

Hi everyone

What is the transient response like of a double chamber bass reflex box that Weem's described?

Where abouts is the notch located? Is it in the passband?

Is efficiency increased at all in dual chamber reflex box?

Adrian

[Ilianh]

As long as Ilianh understands that the fostex enclosure is a different kind of enclosure from the other kind of Double Chamber Reflex with a different response entirely.

Hi Kelticwizard,
Well I noticed it was different, but I dont see in what the response would be entirely different.
Any examples?
Wich is "better"?

Any idea about transient response on those boxes? group delay? impedance?

I heard bad stuff about it, but when I model something in Martin J King's worksheets, everything look preety much as same as a normal ported box.

[claudio]

Hi everyone,
in my site, in the projects area, there is an explanation with measurements of Weems DCR, and comparison with the reflex system.
Hope it helps.

Claudio

[macky888]

Hi CLaudio

Nice looking site, great work!

On the response curves at your site, F2 is a pretty big dip.



But I did notice you said the port response is not included in that curve. Why is this? Where was the microphone placed?

Have you got any response curves with driver + port response combined? Was the dip substantially less when they were both combined?

How did your DCR speaker "sound", to your ears, compared to the standard equivalent bass reflex box? What are the subjective differences in your opinion?

Adrian