Axiom Home Page Forums General Discussion Advice from Axiom Owners BFD - Opinions on My Latest Graph Plot

Here is my plot from the re-eq session tonight. Is this about what everyone calls a "house curve"? Any thoughts from all the experts?. Anyone see anything they think I should change about my curve?

All of my Axioms are blending wonderfully with my twins!!

Updated pic links at the bottom of my post..

Thanks guys..
Rick



TV with Axioms
http://www.stampcometal.com/files/axioms.jpg

Dual SVS 20-39 PC+
http://www.stampcometal.com/files/dualsubs.jpg

Back Left and Rear Back QS8's
http://www.stampcometal.com/files/surrounds.jpg

Rick, I haven't a clue about subwoofer mojo, but I sure do love that entertainment center. A+ home theater in my opinion.

Rick,

First some questions:
Where do you have your crossover set?
Did you play your test tones with only your subs on, or with the subs and mains?
What SPL did you use as reference?

It'll be easier to analyze your graph with these answers.

Rick, as long as the blue line isn't after, you're doing great! Peter raises interesting questions, and I assume that you ran the sub alone. It would help to understand the before peaks if you'd give the room dimensions and the sub position.

Peter and John,

My crossover is set at 80 and the tones were run with my sub and all of my speakers turned on, even the suurounds. I was under the impression that it was correct to have them all on since the plot would determine how they all interacted with the sub. Please correct me if I am misunderstanding this concept.

Regarding the SPL: Since I had such initial high peaks I started with the 16hz tone registering at 70 on my meter. I had read about how hard it is on the voice coils if you run the tones too loud so I was afraid to push it too high. Is there a right or wrong number to start with regarding this as well?

All in all I like how it turned out and what I hear now but I don't want to be staisfied with that if it can even be better!

All constructive help and insight is appreciated.

Thanks guys..
Rick

PS John..yes the pink line is what my final target was and not the blue..Room size is 20x20 with a vaulted ceiling of 8-13 feet and if you looked at the pics the TV is directly across from the blue couch. So the subs are to the left of the main listening area in the corner.

Thanks for the extra details, Rick.

If all your speakers were playing during your measurements, then I see a problem. It is very strange that the right side of the graph (from 80Hz upward) dips so low. Ideally, it should be at the same average level as everything to the left of 80 Hz. This would indicate a problem with your speaker calibration, and not your subs, however.

Your adjusted sub response is very good, so I'd leave that alone, but I'd suggest recalibrating your Axioms to bring them up to the same level (about 85 dB) as your subs.

Peter,

Thanks for your thoughts. After I re-eq'ed my subs I did re-run my calibration levels using my DVE disc to readjust the SPL for my subs. Using DVE I calibrate at 75db on my mains and surrounds and 85db on the subs.

I see your point about the curve should stay higher at the end but how would I get this to change?

I am confused now(but I stay that way most of the time..LOL) I only have one more filter I can use on my BFD and doubt that only one would fix that but most of all they speak against using a filter to add gain, especially since it would be such a large increase.

Note Dennis's graph here..
http://www.axiomaudio.com/boards/showflat.php?Cat=&Board=HT&Number=90033&page=1&view=collapsed&sb=5&o=0&fpart=

Is his big dropoff due to only calibrating using the sub and not using the rest of his speakers or do you know?

Any more info for the confused would be apreciated..

Rick

Do you folks mind if I chime and ask a dumb question? Didn't think so .

Anyway, regarding the graph and in laymans terms, what are you looking at and what should it look like. I suppose in otherwords, what is the graph telling you?
Thanks and excuse my ignorance.

BrotherBob,

The more the merrier!!LOL

If you note my graph...the blue plotted line is the uncorrected SPL (or db) level at each given frequency when that specific tone is played. Note the ups and downs. That means that certain frequencies are played louder (i.e. 28hz & 63hz) or softer (i.e. 100hz) at the same master volume setting . What one wants to accomplish is to have all of the frequencies play at the same level (db)so across the board everything is balanced.

Using the BFD's (Behringer Feedback Destroyer)parametric EQ feature you apply filters at a set frequency to increase or decrease that frequency. It has a total of 12 filters than can be used.

Some users have stated a slight downward slope (the pink line)from the lower frequency to the higher frequencies works well for them. They call this a "house curve". Some try to target a complete straight pink line.

Here is the setup guide for the BFD. It explains it in detail.

http://www.snapbug.ws/bfd.htm

Hope this helps..
Rick

Sure does, thanks Rick.