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Old 5th February 2004, 01:47 AM   #1
Ilianh is offline Ilianh  Canada
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Default Double bass reflex information

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.
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Old 5th February 2004, 05:14 AM   #2
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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.
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Old 6th February 2004, 12:16 AM   #3
REDSKIN is offline REDSKIN  England
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Default dbr/abc boxes

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?
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Old 6th February 2004, 12:20 AM   #4
REDSKIN is offline REDSKIN  England
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Default dbr/abc boxes

DOH! IT would help if I read the links before commenting. Sorry for stating the obvious. More thought before posting me thinks.
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Old 6th February 2004, 12:56 AM   #5
Lusso5 is offline Lusso5  United States
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Good info here with calcs.
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Old 6th February 2004, 06:44 AM   #6
Wizard of Kelts
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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.
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Old 6th February 2004, 07:28 AM   #7
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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
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Old 6th February 2004, 07:02 PM   #8
Ilianh is offline Ilianh  Canada
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Quote:
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.
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Old 6th February 2004, 07:34 PM   #9
claudio is offline claudio  Italy
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Default Weems DCR

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
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Old 7th February 2004, 12:13 AM   #10
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Hi CLaudio

Nice looking site, great work!

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

Click the image to open in full size.

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
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