[drcruz]

Hi all,

I'm the nut case who bought a six channel passive pre-amp from Promiteus (go here: http://www.audiocircle.com/index.php?topic=50970.0 )

Any way I'm tuning in my Force subs (x2) and trying to blend them w/ my mains. To make a long story short, after tweeking and experimenting w/ the ACI sub cal CD, I'm currently getting a nice flat response from ~35Hz to ~95Hz (the flatest response so far). Before I had this UGLY dip at 50 Hz and 110 Hz (settings were 0 phase angle; crossover @ 150Hz; Volume @ 70db's @ 60Hz).

The current setting (w/ flatest response) is Sub "A" @ 0 phase angle; Sub "B" @ 180 phase angle; crossover @ ~80Hz. When I play music though, the bass sounds BOOMY and muddy, when I turn the subs off the bass really tightens up.

I'm sure this is a case where I should "trust my ears", but what's confusing is the measurements look good.

Any advice would be much appreciated. Thanks in advance. 

[bpape]

OK - time to ask the obvious questions. 

- Are you cutting off your mains or doubling the frequencies the subs are covering?

- Have you level matched the subs to the mains and not just worried about frequency response?

- Have you treated the room?

- What does the FR look like with the subs off?

Bryan

[NewBuyer]

Personally and no matter what you end up doing, I think you should always trust your ears on these things - since we do all this so our system will sound good subjectively to our ears, and not to the measuring microphone. I am betting you eventually will end up using your subs, but tweaking them by ear, rather than worrying so much about flat measured response...

[drcruz]

Hey Bryan

- Are you cutting off your mains or doubling the frequencies the subs are covering?

I think this is the area where most of my problem is. There's a big overlap w/ subs and mains, I seemed to get the best (flatest) response when I do this. The mains have this BIG dip around 50Hz, 80Hz and 110Hz in my room. When the subs are measured seperately the subs have a dip around 50Hz and 110Hz. With the subs and mains together and w/ the settings stated above I only have the dip at 110Hz.

- Have you level matched the subs to the mains and not just worried about frequency response?

YES

- Have you treated the room?

NO. Wife will end up in jail for homocide if I accustically treated my family room.

- What does the FR look like with the subs off?

See above

[bpape]

Sorry - must be blind.  Not seeing any plots above or in your links.

In general, we don't want to overlap the mains and sub.  If you must, you might want to play with the slope of the xover to the sub to blend better and knock the level down a few DB.  With the ACI subs, you can also use the dual phase adjustments as a filter of sorts.  You don't necessarily want both phase adjustments the same on the same sub.  There's a lot of flexibility there on that little plate amp.  If you know where you're getting the 'boom', you can kinda filter it out by selective cancellation.

On the other hand, it may be as simple as your room reacting to proper level 50hz instead of the big null.  If that's the case, then treatment is in order (likely in order anyway but WAF sounds like an issue).  Or, you may want to consider bringing 1 sub in below 50hz to reinforce the bottom end but only half the overlap with the mains.

Lots of options. 

Bryan

[drcruz]

Bryan,

You are not blind, it is "I" who is a MORON(!). I'm going to plot one more graph then scan and post them here.

[DR]

You gotta use the ACI crossovers.

 

[drcruz]

That's what I don't get, the measurements look good, but it sounds like crap. 

[DR]

drcruz,

I don't use measurements anymore. Just warble tones and my ears. When I first tried the Sapphire XL's with the Force XL it sounded muddy and confused also. My conclusion was I was loading the room with bass from too many points. The Sapphires really don't need a subwoofer. That is why I now cut them off at 65hz and load the room from a single point below that. It actually works better at 85hz but I can hear the sub.

I assume each of your Forces are located with the mains? As an experiment you might try putting them together. I think Mike even said you can stack them. Then see if removing one load point helps.

One more comment, I listen to all kinds off music. Rock and Pop however are so poorly recorded that I have no choice but to constantly adjust the sub.

Using Jazz and Classical to really get a feel for the sound helps.

Just a thought.

[Mike Dzurko]

Drcruz:

How's it coming along? Lot's of good advice here, just wondering how you're progressing . . . .

[bpape]

You said measurements looked good but it sounded bad.  Have you measured decay time or just frequency response?  Try Room EQ Wizard (free download).  It'll let you look at waterfalls of the room.

Bryan

[drcruz]

Bryan,

I just performed measured freq. response and not decay time.

Mike,

Wehhhllll...

I was planning on posting again, but I wanted to make a couple more graphs for scanning then posting. I just need the time.

But the short version is, I turned down the crossover from ~90Hz to 65Hz and the improvements were HUGE(!). No more muddiness and the mid to upper bass of a bass guitar sounds wonderful. The sub volume might be a little high on the really low part of the freq. range, but that's why I want to take a few more measurements.

I'm so happy w/ the results because music now sounds better w/ the subs on rather than off (before it was the opposite).

I did more tuning for movie LFE, and watching War of the Worlds was THE BOMB (or should I say "THE DEATH RAY").

Like I said, when I get more time I'll do a couple more graphs then post everything.

[bpape]

Good deal.  It's amazing how much difference you can make with careful attention to xover point, xover slope, and phase adjustments. 

Bryan

[DR]

Bryan,

Does Room EQ Wizard work on Vista?

Thanks

DR