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Old 15th January 2008, 03:03 AM   #11
JinMTVT is offline JinMTVT  Canada
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Join Date: Jul 2004
Location: MTL
Focal :

you are doing great with the english ...keep it coming!
i strongly believe that english beeing a "simple" language, it is very good at transferring information even when there are many errrors in syntax or even orthograph..so do not worry ..most of us here are not english borned neway


Please explain your understanding of the planar wavefront , and also about the single/double bass array.
I am currently working on it myself ( design stage )
and would like to use any possible chances to learn more about its use.


Could you take in room measurements at different location ? do you have any mean of measuring room modes in your setup ?
i've very like to see how it performs on the lateral and vertical modes ...

if you have interesting links about DBA, please !LINK! US!

what is the Xover freq. of your front sub ?
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Old 16th January 2008, 07:31 AM   #12
focal is offline focal  Germany
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Location: Near Dresden/ Germany
Hi Jin, thanks for flowers .

This forum is a good possibility to learn english by doing.

In moment i have few time, I am at work

With a SBA ( better DBA) you eliminate the room modes in the length of yor room. This is the result of the planar wavefront ...

The roommodes in width and height are ever existent, but her energylevel is smaller as without SBA.

I have not understand the pysically theory of this phenomenon.
In the german forum named HiFi-Forum are a few experts of this theme an they helps me.
Look here:http://www.hifi-forum.de/index.php?a...72&thread=1358

I think the user poison nuke is good in english conversation and helps you friendly.

Briefly:
A DBA are two SBA, one in front, one in rear of your room.
The second SBA must have a inverted signal and you must make a timedelay between the SBA's.

A must have for the perfekt function of a SBA/DBA is a cuboid ( ashlar?)- shaped room.
Any jutties (?right word?), alcoves and so on, deranges the function of DBA.

My x-over frequence is 125 Hz.

Greetings

Uwe
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Old 19th January 2008, 03:18 PM   #13
focal is offline focal  Germany
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Dear friends,

some new pics.

I have finalized the speaker-covers ( the right term?)

Click the image to open in full size.

Click the image to open in full size.

Greetings

Uwe
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Old 20th January 2008, 04:45 AM   #14
JinMTVT is offline JinMTVT  Canada
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Join Date: Jul 2004
Location: MTL
covers is ok i guess
i often see the use of : "driver grille"

Will you be able to take measurements of the low frequency response of your system at different location in the room ?

you should try and measure the influence of modes on your system with the DBA approach ..

maybe measure response very close to driver
and then compare to measurements at listening location
and others ..

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Old 26th January 2014, 06:09 PM   #15
focal is offline focal  Germany
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Location: Near Dresden/ Germany
Default System Upgrade

Hallo my friend,

it is long ago, since i was here . My english language is not better, altough i had vacations in Toronto Canada last summer. Sorry.

I have made some changes:

First: I built new boxes for the Jim Thiel Coaxial Speakers. A lot of 22 mm ( 1") Birch MPX Layers was stapled one above the other and fixed with glue.

Finally the boxes was encased with veneer.

The stand is a 100 mm (4" ) Steel Pipe, filled with dry sand.

The bottom platform is also steel.

Here you see the new front, lamps on:
Click the image to open in full size.

Detail with lamps off:
Click the image to open in full size.


Second: The big Change; I finalized the rear SBA: The DBA is complet.
This are the same TangBand Speaker like in front , tough without covers/ Speaker grills. One also sees my library of SF-books.
Click the image to open in full size.

Detail with a view to my small vinyl collection.
Click the image to open in full size.


Finally: My haunt:
Click the image to open in full size.


I hope you have a little fun with my article.


Best greetings

Uwe
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Old 26th January 2014, 06:16 PM   #16
adason is offline adason  United States
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now that's a candle!
very nice focal
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Old 26th January 2014, 07:22 PM   #17
focal is offline focal  Germany
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Join Date: Jan 2008
Location: Near Dresden/ Germany
Thank you adason.

My listening room is in the Basement of my house.

Previously was this a storeroom für potatoes and somethings.

The walls are all massive stone, the ceiling and the bottom is concrete.

Under the concreteceiling was mounted a ceiling from plasterboard , to hide heating- and water-pipes .

L/W/H: 6,1m ( approx 20') /3,4 m (approx 11.5')/2,05 m (approx 7').

The DBA make in this small room an amazing bass, clearly and without any boom and rumble. Unbelievable. I am very satisfied.

Greetings

Uwe
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Old 10th April 2014, 01:13 AM   #18
JinMTVT is offline JinMTVT  Canada
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guten tag Focal,

sorry to be late on the comeback,
haven't been on that site since i started to build my new house ~ 6 years ago ..

I was wondering,
why have you not place your sub array in a manner
that it would make a perfect mirrored infinite planar wave ??

After our discussion on this thread, back then ..
i went on to search and think about how i would build my HT/music room in my new house and finally decided upon a "mirror" type front array
of subwoofer that "should" provide with a approximation of a planar wave
type output, to help alleviate lateral and vertical room modes.

your current setup still exhibits those modes right ?
Only the forward/backward mode is removed ?

Here is a picture of how i have positionned the 16X 15" subwoofer holes
in the front wall of the room.
Attached Images
File Type: jpg htsubsetuppic.jpg (96.7 KB, 23 views)
File Type: jpg 2blocs.jpg (92.3 KB, 25 views)
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Old 10th April 2014, 04:01 AM   #19
puppet is offline puppet  United States
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^ Is that a footing or air bag under your walls?
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Old 10th April 2014, 03:15 PM   #20
JinMTVT is offline JinMTVT  Canada
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Join Date: Jul 2004
Location: MTL
Quote:
Originally Posted by puppet View Post
^ Is that a footing or air bag under your walls?

It is obviously some VIP bags stacked together for improved insulation!!
( vacuum insulated panels )


canadian simple footing forms...

Fastfoot Residential Overview
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