[tryan77]

Looking for some ideas on where you guys set your x-overs at and what you guys think "sounds good". I know that it is different for everyone because of taste and preference but I am still curious.

Lows - Mids - Highs and Slope

Just starting to get my head around tweaking and tuning and I am curious to see what you guys set them at. It would also be nice if you could state "why" you set them where you did, did you set them there because thats what you have always used and liked, or did you just tinker until you think you got it where you want it with your latest setup?

 

[tryan77]

Come onnnnn....

 

[chad]

It's like asking "should I do it?"

 

[tspence73]

I was thinking about starting a thread about this very topic. A couple of days ago, I was listening happily to my system when I noticed a vocal resonance that I didn't like coming from my fiberglass kickpanel. I knew it wasn't the speaker, but the actual kickpanel itself vibrating at what sounded like 150-250Hz range. I recent put my highpass on the kickpanel to 150Hz.

After hearing that vocal resonate the kickpanel on that track, then I started hearing the same resonating on acoustic guitars! ARGH! I HAD ENOUGH!

So, yesterday after work, I went to town on my car trying to figure out how to minimize or remove the resonating tone on vocals and some acoustics bass instruments.

I turned up the highpass on my amp to 250Hz(it's max). I turned off my subs and disabled my midbasses. Then played a few seconds of a track that resonated the panel over and over and over again. Making EQ adjustments and volume adjustments then realizing the slope of the highpass just wasn't steep enough at 18db/octave to kill the upper bass resonance.

So, I re-connected the active crossover's "high-pass" section to the RCA line going to my amp's kickpanel input jacks. (I was just using the active crossover to lowpass the midbass to complete a bandpass.) So the active crossover's highpass was turned up to 300Hz and used in conjunction with my amp's 250Hz highpass to effectively give as steep a slope as I could get.

I found I actually needed every bit of that slope and maybe a tad more. Finally, at moderate volume the resonance was gone and only at high volume 95db+ SPL does the resonance get audible to a small degree. I lowpassed my midbasses at 270is and boosted their output a tad then compensated with a lowering of 160Hz & 400Hz (400Hz for the lack of lowpass filter steepness to match the highpass on the kick) on my EQ while keeping the deeper bass at 60Hz up at normal output. I found my midbasses play this upper bass region without resonance because the door is so well treated.

I reblended the sub-50Hz subwoofers in and then after a bit of midrange EQ trial and error ended up with a beautiful sound with no resonance and just this velvety sound. Add to that, being able to hear deeper into just about every mix.

After achieving this tuning result, I couldn't stop listeining to music. People who passed by must have thought I was crazy. I sat in my car for 3 hours enjoying track after random track and hearing things I either didn't hear before or haven't heard in years since I had a good home audio system. A particularly pesky track that makes my computer speakers resonate, and my kicks resonate is the Brian Eno - Dune Prophecy track. There is a very high synthetic upper-bass tone that hangs that makes most plastics hum and resonate that are directly coupled to the driver. I think the ensolite under the fiberglass perch in the door has decoupled the midbass enough to really reduce most direct resonances.

So, IMO if you can identify something in your sound or acoustics that you hear that just craps on the experience, tuning or adjusting can fix those issues. I think I'm just lucky that my midbasses in my doors are acoustically treated well enough to be able to move a problem frequency to a location where it doesn't give issues.

 

[chad]

Spence, do you have a CD of test tones? i think the Focal downloads posted here have a test or tools disc, that helps a bunch for finding stuff like that. But you may find that a single pure tone won't drive it as nuts as say a guitar tone with a bunch of harmonics in it.

Another thing to try, If you have a center console in your car, if it's ever out, fire up the system and listen to it without the console in, you will be amazed at what is going on with that thing in terms of guiding and reflection. Also, just for grins, if you find an issue at say, 160, do a light cut at 320 just to see, sometimes that helps.

 

[tspence73]

Well, I fixed it. I don't necessarily think of it as a 'bandaid' fix as the crossover frequency is still low enough that it didn't effect imaging and the issue has been eliminated from audibility. There might still be a resonance when going with high SPL, but I can't hear it when the system is really loud. That's likely due to masking effects of neighboring frequencies reaching a threshold that masks the resonating fiberglass.


So, other than moving the problem to another location, what are some good ideas to eliminate fiberglass resonance in upper-mid bass? I appreciate the advice Chad, but I used a steep highpass slope by running my active crossover's HP @ 300Hz and my amp's xover @ 250Hz (it's limit) to create a 36db/octave slope (or something close to it) to keep those pesky tones away from my kickpanel's midrange, then I used a bit of EQ trickery at both 160Hz and 400Hz off my HU's EQ. It has worked so well, the SQ has jumped to a whole other level. It seems there is a lot to be said about killing resonances and acoustic vibrations (especially resonances you didn't even notice you had at first) when aiming for high end sound. Plastic and fiberglass seems to be very susceptible to midbass tones and those issues aren't so easily kicked as metal is with damper.

 

[tspence73]

Once you identify the source and the reason, you can attack it by either moving the resonance out of the driver passband (adding mass or making it more rigid, each takes it in a different direction) or if it is two pieces hitting one another, isolate them with ensolite or something similar.

I might not be able to. The fiberglass is molded to secure fit to a metal rail on the side of the car just under each door. So, it's a direct fiberglass-on-metal contact that is secured by a screw at two locations. One location is on the rail and the other is only accessible 'inside' the kick and forces me to remove the midrange driver to get to it. The rail portion is where the fiberglass is bare but on the back of the pod, it's got the fabric shielding it a bit. I know it's the fiberglass that is resonating likely because it's a smaller pod. Not really big and 150Hz or so at high SPL makes a heck of a resonance for a small pod.

This unfortunately might be a problem I have to live with and I have resolved it with a steeper highpass slope and a bit of EQ trickery.

 

[tspence73]

I'd be suspect of that fg to metal contact point. That's the sort of place I use some foam weather stripping tape prior to bolting something down.

The problem is, the rail is the very place the pod is venting into the frame of the car, so I can't have anything obstructing the venting so as to keep the design as close to IB as possible.

 

[J0ne]

I hate my Xover settings because I hate my drivers.

does that help?

 

[falkenbd]

The problem is, the rail is the very place the pod is venting into the frame of the car, so I can't have anything obstructing the venting so as to keep the design as close to IB as possible.

fiberglass touching metal wouldn't be happening in the vent itself. its the area around the vent that i'd be worried about.

writing stories about your kick panel isn't really relevant to this thread.

To the OP: Is there a specific problem you are dealing with? (besides tspence dumping in your thread)

 

[falkenbd]

Also to the OP: There are a bunch of nice threads here on tuning. Check out the tutorials section.

 

[tspence73]

(besides tspence dumping in your thread)

I thought the info in this thread would be helpful to the OP. Hmm. I meant well anyway.

 

[chad]

I thought the info in this thread would be helpful to the OP. Hmm. I meant well anyway.

you dun fine.

 

[MiniVanMan]

I thought the info in this thread would be helpful to the OP. Hmm. I meant well anyway.

Nope, just fine. Hopefully you're seeing the difference between constructive dialogue, and non-constructive babbling.

Actually there is some good dialogue in this thread. Now back on topic.

 

[falkenbd]

I thought the info in this thread would be helpful to the OP. Hmm. I meant well anyway.

ya i kind of jumped the gun. i reread your stuff, sounds very helpful.


hopefully the op comes back

 

[Hillbilly SQ]

My crossover settings are where they are because it keeps my drivers well within their usable passband and most importantly the slopes used have them in ACOUSTICAL PHASE. I'm willing to bet more than half the people on here don't even have their speakers in ACOUSTICAL phase

 

[falkenbd]

My crossover settings are where they are because it keeps my drivers well within their usable passband and most importantly the slopes used have them in ACOUSTICAL PHASE. I'm willing to bet more than half the people on here don't even have their speakers in ACOUSTICAL phase

Good point, there are a lot of things crossovers can do for you. Do you set your crossovers where you know the acoustical phase will be correct? Or do you adjust phase after you find the slope you like?