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[timmotte]

hi,

i got a few questions. my setup is win7 64 with m-audio 1010 interface which provides 8 analog outputs. so basically im running a 4.1 system. fine actualy but,

1. my sub lowpass is done by the JRSS engine which works fine . but if im experimenting to manage lowpass with p.equalizer (lowpassfilter 80hz) then the the soundlvl becomes very very low. even if i use roomcorretionto to boosts the channel (sub)  with +20db (=max) its nearly unnoticeable.  this setup uses "stile" to manage bass correction or how it is called.

2. linkwitz riley: i know what it does but cant get it working properly. i would need a simple explaination of the parameters and how to implement it usufully.

thank you for your time

[Jargon]

A Linkwitz Transform is used in sealed subwoofers mostly in order to extend their output to a lower octave.

To properly implement it and to avoid damage you need to know certain values of your sub.

Unless I am mistaken, the Fz and Qz values correspond to the FS and Qs of your subwoofer which are values that must be known by the manufacturer or you if you built it.

Then the Fp and Qp values are the the frequency you want to extend to and the new total Q of the system which also determine the BOOST applied to that range. There is a spreadsheet on the LInkwitz website that allows you to see the total boost required after entering the new Fp and Qp values.

It is very easy to clip the amp or damage the driver of the sub if you don't know what you are doing though and unless you know your sub and amp limits be very careful.

If you have a ported sub do not even bother.

So what sub are you using?

[timmotte]

hi,

thanks, would you give a example with following details: its visaton tiw250 8 ohm (2x) running on a 250w rms amp


Technische Daten
Nennbelastbarkeit    200 Watt
Musikbelastbarkeit    350 Watt
Nennimpedanz Z    8 Ohm
Übertragungsbereich (-10 dB)    fu - 3000 Hz
(fu: untere Grenzfrequenz abhängig vom Gehäuse)    .
Mittlerer Schalldruckpegel    89 dB (1W/1m)
Grenzauslenkung    20 mm
Resonanzfrequenz fs    31 Hz
Magnetische Induktion    0,95 Tesla
Magnetischer Fluss    1500 µ Weber
Obere Polplattenhöhe    10 mm
Schwingspulendurchmesser    5 cm
Wickelhöhe    2,5 cm
Schallwandöffnung    23,2 cm
Gewicht netto    4,4 kg
Gleichstromwiderstand Rdc    5,8 Ohm
Mechanischer Q-Faktor Qms    4,39
Elektrischer Q-Faktor Qes    0,35
Gesamt-Q-Faktor Qts    0,32
Äquivalentes Luftnachgiebigkeitsvolumen Vas    80 l
Effektive Membranfläche Sd    315 cm2
Dynamische bewegte Masse Mms    45 g
Antriebsfaktor Bxl    12 T · m
Schwingspuleninduktivität L    2,35 mH

thanks tim

[Jargon]

I am no expert in this and I am also trying to learn but let me first understand a few things. Is this German? I don't speak German.

These are the driver parameters not the subwoofer as a speaker correct?

So you are running two of these 15"? How have you wired them? In series? Parallel?

First of all the amp seems small to me even without applying an LT but the most important thing is whether they are within a sealed or ported enclosure and what are the dimensions of the boxes? You need to have the measurements (anechoic or at least ground plane) of the speakers (subwoofers).

Yet bear in mind that to increase extension one octave below the FS of the speaker you might need up to 16 times more power from the amp than the Fs down there yet you will still be lower SPL wise at that point.

[timmotte]

thanks jargo, yes its german. the full box is this, but without crossover or mid or hights:

 http://www.visaton.de/de/bauvorschlaege/archiv/vox252/index.html

it says 28hz @ -10 db (70l volume)

my intention is to get a nice cinema sub. your concerns i do understand but the room is only 20² plus soundlvls are quite human.  so what you suggest to start from?

tim