Advice needed...sub/tweeter phasing, etc.

[Richard G. Pecoraro]

I've been lurking this group for a while, and am by no means an expert audio
person; please keep that in mind if my questions seem a bit naive.

I have a 97 Mazda MX-6. Focal 165K in front, stock 5X7 in rear, 2 12" RF
DVC subs in prefab 1.25 cu. sealed enclosures.

My initial impression was that the bass was muddy (in layman's terms I
couldn't 'imagine' the bass pedal hitting the kick drum). I initially
thought this was a midbass problem, since I hadn't dynamatted the doors.

I played around with the Head Unit's parametric EQ and discovered that it
wasn't a midbass problem...if I boosted at the crossover frequency (3.5 khz)
I had the snap back and it sounded 'better'.

Keep in mind I brought much of this on myself, as the mids are in the door
and the tweeters are on top of the dash. (I didn't want to mess with
building custom kickpanels for the focals, maybe another day.)

Anyway, I discovered that if I reverse the phase of the tweeter and Subs,
leaving the mids alone, I don't need to have the 6db boost at the crossover
frequency, and the pedal hits are still crisp. Undoubtedly the separation
between mids and tweeter was causing considerable cancellation.

I'm not sure, however, how this has effected the high end. The tweeters are
still fairly smooth, I just think they are perhaps a bit less defined? less
'up front'? I could be imagining this as a result of the improved upper
midrange response.

I know many people have experimented with sub box placement and positioning,
and done testing, etc. Is there any comparable info on tweet/mid phasing
and it's consequences? Would I get the same result if I 'un' phased the
tweets and mids and just reversed the phase on the mids?

Thanks for any responses,
Rich

[MOSFET]

The reason you don't hear people as concerned about phasing issue involving
tweeters is that high frequency sounds are very directional and generally
the sound from your tweeters reach your ears before interference with the
other tweeter can occur.

With lower frequencies this is not the case. Bass goes EVERYWHERE and
considerable cancellation can occur before the sound reaches your ears.

Of course, cancellation CAN occur with high frequencies and should not be
ignored. But in your case, focus first on low frequency cancellation
issues. Hope this helps.

MOSFET

"Richard G. Pecoraro" > wrote in message
...
> I've been lurking this group for a while, and am by no means an expert
audio
> person; please keep that in mind if my questions seem a bit naive.
>
> I have a 97 Mazda MX-6. Focal 165K in front, stock 5X7 in rear, 2 12" RF
> DVC subs in prefab 1.25 cu. sealed enclosures.
>
> My initial impression was that the bass was muddy (in layman's terms I
> couldn't 'imagine' the bass pedal hitting the kick drum). I initially
> thought this was a midbass problem, since I hadn't dynamatted the doors.
>
> I played around with the Head Unit's parametric EQ and discovered that it
> wasn't a midbass problem...if I boosted at the crossover frequency (3.5
khz)
> I had the snap back and it sounded 'better'.
>
> Keep in mind I brought much of this on myself, as the mids are in the door
> and the tweeters are on top of the dash. (I didn't want to mess with
> building custom kickpanels for the focals, maybe another day.)
>
> Anyway, I discovered that if I reverse the phase of the tweeter and Subs,
> leaving the mids alone, I don't need to have the 6db boost at the
crossover
> frequency, and the pedal hits are still crisp. Undoubtedly the separation
> between mids and tweeter was causing considerable cancellation.
>
> I'm not sure, however, how this has effected the high end. The tweeters
are
> still fairly smooth, I just think they are perhaps a bit less defined?
less
> 'up front'? I could be imagining this as a result of the improved upper
> midrange response.
>
> I know many people have experimented with sub box placement and
positioning,
> and done testing, etc. Is there any comparable info on tweet/mid phasing
> and it's consequences? Would I get the same result if I 'un' phased the
> tweets and mids and just reversed the phase on the mids?
>
> Thanks for any responses,
> Rich
>
>

[MZ]

Ditto what MOSFET said. When it comes to phase, it's not the tweeter's
interaction per se, but the interaction between the tweeter and midrange
speaker. In fact, most component sets already have the tweeters wired out
of phase, mostly to account for the phase shift caused by the crossover. So
what I suspect you're doing is adjusting the relative phase between the
midrange and tweeter. Play around with it until it's where you like it.

And yes, aiming is crucial. Perhaps even more crucial than the quality of
the tweeter itself! Note also that "directly pointed at you" is not always
best. Try 20-30 degrees off axis, or even bouncing off the windshield.

No one said it was easy. You could spend months tweaking...


"Richard G. Pecoraro" > wrote in message
...
> I've been lurking this group for a while, and am by no means an expert
> audio person; please keep that in mind if my questions seem a bit naive.
>
> I have a 97 Mazda MX-6. Focal 165K in front, stock 5X7 in rear, 2 12" RF
> DVC subs in prefab 1.25 cu. sealed enclosures.
>
> My initial impression was that the bass was muddy (in layman's terms I
> couldn't 'imagine' the bass pedal hitting the kick drum). I initially
> thought this was a midbass problem, since I hadn't dynamatted the doors.
>
> I played around with the Head Unit's parametric EQ and discovered that it
> wasn't a midbass problem...if I boosted at the crossover frequency (3.5
> khz) I had the snap back and it sounded 'better'.
>
> Keep in mind I brought much of this on myself, as the mids are in the door
> and the tweeters are on top of the dash. (I didn't want to mess with
> building custom kickpanels for the focals, maybe another day.)
>
> Anyway, I discovered that if I reverse the phase of the tweeter and Subs,
> leaving the mids alone, I don't need to have the 6db boost at the
> crossover frequency, and the pedal hits are still crisp. Undoubtedly the
> separation between mids and tweeter was causing considerable cancellation.
>
> I'm not sure, however, how this has effected the high end. The tweeters
> are still fairly smooth, I just think they are perhaps a bit less defined?
> less 'up front'? I could be imagining this as a result of the improved
> upper midrange response.
>
> I know many people have experimented with sub box placement and
> positioning, and done testing, etc. Is there any comparable info on
> tweet/mid phasing and it's consequences? Would I get the same result if I
> 'un' phased the tweets and mids and just reversed the phase on the mids?
>
> Thanks for any responses,
> Rich
>