From SBA to DBA (thread titled changed 14/01/29)

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Dear friends,

I am new in this forum.

I apologize me for my bad english language .

I have build a Single Bass Array in my hearing room at the cellar.

The main speakers are a pair of Jim Thiels SCS3 neo. In my ears, one of the worlds best speakerdrivers!

But I heard, its better to take far away deep frequencies of it.
( ohh my english...it's hard to write without experiences)

So I have build 4 Enclosers with 2*2 Tang Band W69 drivers = 8 drivers in front of my room.

The crossover is a digital Alto maxidrive 3.4 pc.

The amplifier for the SBA is a Pioneer M90a
The amplifier for the Thiels are two Marantz M500
Control amp: Pioneer C 90a
CDP: Marantz 7300
Turntable: Transrotor Leonardo with SME 3009 arm and Grado prestige silver pickup


An externally hosted image should be here but it was not working when we last tested it.



So, I hope my first post have success.

Greatings

focal
 
Looks like you can have lots of listening fun in such a dedicated room :)

Are the big things between the bass arrays and the wall corner bass traps? Do they help alot?

Depending on your listening height, the smaller absorbers could be placed lower, if you want to get them into the way of the first sidewall reflection. It looks like they are placed in the height of a standing person, not a sitting one.
 
Dear friends,

thanks for the warm welcome.

@mavo: yes i have a lot of fun in my cellar:D

The big things are corner traps - bassabsorbers ( naturally DIY)

The wall absorbers have the right position. I was trying one year to find this position. In lower position the absorbers take off, too much high frequencies and i have a flanelly sound ( is this the right word?).

Greetings

Uwe
 
its good that you found the best position by testing, i too often try to make everything perfect by theory and not by actual testing :-(

some people even say, that sidewall absorbers are evil, since they are too small to achieve a broadband absorption, so you only absorb high frequencies, and still have the midrange reflections, confusing the listener. well, so much for theory - even better if it works nice in reality :)
 
Welcome to this board Focal!

Was the positionning of your subs predetermined to have an impact ?
you say single bass array ...cause you've split it from a double bass array ? :p

I had never seen such drivers with a squared cone for subwoofers.

Have you made any measurements for the subs in your room ? i wonder how your sub placement has an impact on room modes .
 
Dear friends,

now I was sitting 6 hours in my listening room and i have heard many LPs and CDs.

It is stunning, how many new details are to find on this wellknown discs!

Not only, because more deep frequencie information can be heard, but also because the Thiel SCS3neo is exempt from hard work.

I'am so happy. It was the best decision im my hifi carrier to built this bassarray!

Bad roommodes has never a chance. The SPL-Level in deep frequencies ( 30...100 Hz) is constantly +/- 2 dB at every places in my room!

Here you can see the frequency-response at hearing-chair.
(smoothed 1/1okt.)

Greetings

Uwe
 
Hi Jin,

yes, the SBA is a half of a DBA.

DBA is the very best way to build a subwoofer.

SBA is the first step to realize this.

You wonder why a SBA can have an impact of the room mode???

My english is too bad to give you explanation in this case.

Please search the net for more informations!

Briefly: A SBA makes not a globular soundwave in a room, but it makes an planar wave! This is reducing roommodes considerabelly.

New try for post a pic ( ist very difficult in this forum, this is probably the reason why I can't see very few pics here).

An externally hosted image should be here but it was not working when we last tested it.


You see the frequency response on my listening chair, ( smoothed 1/1 okt.)


The Chassis are Tang Band W 69. The area are like a 8" Chassis.


Greetings

Uwe
 
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 ?
 
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:smash:

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?action=browseT&back=1&sort=lpost&forum_id=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
 
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 ..

:)
 
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:
An externally hosted image should be here but it was not working when we last tested it.


Detail with lamps off:
An externally hosted image should be here but it was not working when we last tested it.



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.
An externally hosted image should be here but it was not working when we last tested it.


Detail with a view to my small vinyl collection.
An externally hosted image should be here but it was not working when we last tested it.



Finally: My haunt:
An externally hosted image should be here but it was not working when we last tested it.



I hope you have a little fun with my article.


Best greetings

Uwe
 
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.:D

Greetings

Uwe
 
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.
 

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