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The Dude
12-25-2008, 02:55 AM
Ok Due to moving my sounds into a different room i now have the old "sub too big/Room too small" problem which results in crappy sounding bass. Is there anything at all i could do to compensate? I have a JBL 4645c sub with a Citronic PPX 900 amp runnin in mono mode and a 100 Hz low pass filter. can set the LPF to 50Hz if i want and i have a basic EQ with 25,40,63 and 100 Hz bands.

Don Mascali
12-25-2008, 07:01 PM
The most productive thing may be to move the sub and/or your seating position around and make sure you're not sitting in a null zone.

Also check your wiring and make sure you are not phase reversed to your mains.

Don C
12-26-2008, 10:36 AM
One of these inexpensive kits can help with measuring the problem.
http://www.harmanaudio.com/search_browse/product_detail.asp?urlMaterialNumber=RABOS%20KIT

The Dude
12-26-2008, 12:24 PM
The RABOS kit could be good.Might pick one up just for the sake of it,but could maybe,with a bit of begging,get a loan of an ARTA 80 real time analyser. probably a good idea to to check that some way or another.as for phasing and wiring, all is positive to red = forward piston movement,but since you mention it, i might try phase reversal on the sub only.i have somewhere a little switch i wired up so i could reverse phase quickly. if i can find it and its wiring,ill hook it in for a couple of days and have a good listen. thanks for taking time to help.Much obliged.:)

boputnam
01-02-2009, 07:17 PM
...crappy sounding bass.
It may be, or may not be, that phase is the "new" issue - everything was OK before, right? But it's difficult to give advice - we know little.

How different is the "new" configuration? Are the mains and sub in the same relative positions (but in a different room)...? Try inverting the sub, but if the positions are the same it is unlikely the relative phase between the two is now a problem.

What was it you liked before about the sub response that is now missing? It could be your listening position was at a lobe and the listening position was not representative of the overall sound - but, you got used to it. Now, you may not be siting at a lobe and you miss that character.

Are their unintended bass traps in the new room?

Like I said, we know little about the two conditions - old and new. Makes it hard to diagnose... :dont-know

JBL 4645
01-04-2009, 05:31 PM
Hey Dude

There is free download of (REW) Room Equalizer Wizard once joined up with Home Theatre Shack. The software would require a simple basic measurement microphone and preamplifier. Behringer is cheap as biscuits for (ECM8000 mic and MIC100 preamp) though digital village or any other PA studio suppler in the UK.

The package is easy to use to find the frequency response at listening position to see how many dips and peaks that need attending too within your room.

The programs function is to work with parametric EQ Behringer BFQ2496 can’t remember model number for the DSP unit? I think the DSP is, discontinued the BFQ2496 I think is still in current production. All three units shouldn’t cost no more than £200.00 The BFQ2496 offers 20 bands of parametric EQ on each channel A and B, I use one myself.

Here is the sites main page, to download you have to register with the site and the guys there are quite friendly and more than willing to help you out with the program and unit.
http://www.hometheatershack.com/forums/ (http://www.hometheatershack.com/forums/)