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Frequency humps and dips
Ok, my turn I guess. Let's discuss what exactly in a car causes spikes and dropouts in a car. I KNOW every vehicle has them.
For those who don't know I have a 2001 Accord 2 dr with an 8" sub/midbass in each door, a mid in the kicks and tweeters in the factory dash locations. To somewhat mitigate the 315 Hz suckout, I moved the xover point to around 400 Hz. I know Kirk has an Acura TL (same basic car) and he has the same 80 Hz hump (his mids are in the doors) which leads me to believe that location is causing the hump. Would be interested to hear other peoples thoughts, experiences, and observations.
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Re: Frequency humps and dips
I'm curious to take some measurements to see how the windows affect the output. I had brought up the idea of doing some plots with the windows either open or covered in such a way that they are not an issue, and compare it to a plot with the windows closed (exposed). I know that you can't really do very much to counteract glass, but until you eliminate them from the equation, you can't see what other problems exist.
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Re: Frequency humps and dips
My car sounds VASTLY different with the front windows down
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Re: Frequency humps and dips
Yeah, and I'm sure all cars do. My point is if you have a problem with a certain frequency and you attribute it to reflection off the window, it's possible that it's not the window, but an issue elsewhere. How will you know unless you eliminate the window from the equation?
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Re: Frequency humps and dips
My issues, same freq, opposite effect, is caused by the footwell building up. When you remove the console it mostly goes away.
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Re: Frequency humps and dips
I can developed the window thing even further, check it........when I open a window (front) the stage changes, of course already been mentioned....but try this...as I open and close, or make minute changes in size of opening, it changes as well. Its funny because I've tuned my car with open and closed, just for fun, and the changes to the tunes are miniscule...but the changes to the sound are not. The changes in the stage with small increment adjustments to the window level demonstrate just how much reflections are influencing my sound. Its amazing that such small angle changes of the reflective surface, can so dramatically change what you're hearing!
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Re: Frequency humps and dips
Does hanging softer surfaces, towels, sweatshirts, et cetera over the hard surfaces noticably change the reflections ?
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Re: Frequency humps and dips
I don't know.....ill try and get back.
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Re: Frequency humps and dips
it makes a big difference in the higher freq's. A 1" towel or foam will only absorbs freqs like 3.5 KHz and above if I did my math right, so not much for mids/lows
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Frequency humps and dips
I have a dip around 300-315hz and I compensated by running my dash speakers down to 250. That took care of that. I also have a suckout at 125hz that I can remedy by flipping polarity on one of my midbasses but then the rest of the midbass bandwidth goes to shit. So I just let my subs handle that. Crossed at 80 hz, 2 15s still retain lots of punch at 125 hz. Just enough in my car to make it sound right.
Sent from my Springfield XD with love!
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Re: Frequency humps and dips
Harmonics can also play a role. If you have a "suck out" try boosting the octave above or below, and conversely if you have a hump that you cant cut enough to flatten it out try the octaves above or below and cut them to help with your issue.
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Re: Frequency humps and dips
Quote:
Originally Posted by
chefhow
Harmonics can also play a role. If you have a "suck out" try boosting the octave above or below, and conversely if you have a hump that you cant cut enough to flatten it out try the octaves above or below and cut them to help with your issue.
It's difficult to fix a physical problem with an electrical solution
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Re: Frequency humps and dips
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Re: Frequency humps and dips
Quote:
Originally Posted by
PaulD
It's difficult to fix a physical problem with an electrical solution
Difficult but not impossible. Another tool in the box is never a bad thing.
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Re: Frequency humps and dips
Quote:
Originally Posted by
chefhow
Another tool in the box is never a bad thing.
That's what she said.
Sorry, couldn't resist :neener:
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Re: Frequency humps and dips
Sorry hic, forgot to report back on the matter....... yes, I played with some of my thick bath towels and had some surprising results.......I had been told before about the need of a dashmat so I started there first.....I think because of my mids and tweets being forward of the dash, there was no discernable changes with the dash padding......but, when I double draped the towels, and closed them in my side windows, it led to a total returned.of said mids and tweets......the result was a slightly sharper focus.....nice..since I knew that this wasn't going to stay I didn't work the tonality all the way through, bit it gave me a nice peek into what reflections were doing in my car......a lot.
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Re: Frequency humps and dips
the top half of the interior is almost all glass, reflections are the name of the game
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Re: Frequency humps and dips
I can solve the reflections for about 50% by dropping my top and opening the windshields.. :D
Aiming is important too... Try to aim on axis, as soon as you want or must install off-axis I recommend to aim the drivers to the least reflective surface..
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Re: Frequency humps and dips
That's why my drivers are aimed toward the roof behind the dome light. This way
-they aren't very far off axis adjacent to the listening position
-each speaker is close to the same degree off axis
-the head liner minimizes reflections
-what does get reflected reflects back toward the rear windshield and rear deck
I also have my drivers set forward of the a-pillars (closer to the listeners) to minimize diffraction. I'm sure I am getting some diffraction and reflections off my dash though because my stage sounds a bit diffuse in certain areas. I have yet to address this but I'm hoping a dash mat will help.
Sent from my Springfield XD with love!
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Re: Frequency humps and dips
one of the simultaneous issues/saving graces, of a 4-way install is you can limit the amount of reflection issues.
wide-bander and mid bass 2-way is stuck with that wide-bander's location limitations, one of the things I don't like that much about putting the wide-bander up in the A-pillars or dash.
I like the door spot, just above the knees and it would figure that the width of image is best here, but stage is a little more lop-sided than kick panels.
I can get used to the expansive image when I'm not listening to a compression driver system, which is another animal.
I'll say it here again, (probably going to do a lot of repeating) in that the Aura MR series braxials, had a unique design.
You had a known distance for the passive crossover to function from, but if you turned the entire speaker it put the tweeter's tilt on axis, or slightly near it.
This has the benefit of mating the dispersion of the tweeter's beaming with the woofer's beaming, or basically, it was like aiming two flashlights. By turning the speaker, you could get both directivity patterns to coincide, or mesh at some point in the speaker's axis.
This made for a more cohesive image, and even if you had the Aura emblem "cocked" a bit, it was an aesthetic price well paid for the sonic attribute of a matched output.
OR, I didn't care that the speaker wasn't "squared" because the sound was what I was after.
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Re: Frequency humps and dips
Quote:
Originally Posted by
cajunner
This has the benefit of mating the dispersion of the tweeter's beaming with the woofer's beaming, or basically, it was like aiming two flashlights. By turning the speaker, you could get both directivity patterns to coincide, or mesh at some point in the speaker's axis.
I could see the benefits of a co-axial design for the point-source of them, beaming of the pattern would be if you pushed the limits at x-over points (I think ).
I own a set of MR62's
Quote:
Features Common to all RPM Stage II Speakers are:
• Polypropylene cone for durability, weather resistance and low distortion
• Patented NRT neodymium magnet structures for high excursion, extended bass response, low distortion and high power handling
• Rubber surrounds for deep bass and long life
• Hi-fidelity quality, soft-dome tweeters in all configurations for extended and smooth high frequency response
• High-grade steel frames provide universal mounting as well as strength to avoid flexing
• Shallow mounting depth to fit most common vehicles
6 x 9" 2-way Coaxial Speaker System
The RPM6900 features a 1" soft dome tweeter.
Frequency Response: 28 Hz - 30 kHz.
Peak power: 240 W.
Continuous power: 60 W.
Impedance: 4 ohms.
Sensitivity: 92 dB @ 1 watt/1 meter.
Includes grilles
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Re: Frequency humps and dips
Quote:
Originally Posted by
Hic
I could see the benefits of a co-axial design for the point-source of them, beaming of the pattern would be if you pushed the limits at x-over points (I think ).
braxial is off, time-wise but it's not far enough to matter considering the distance to centers.
what an MR braxial has is an angled tweeter, and I guess the JBL Gti braxials are in this same camp, I believe they also have the angled tweeter, and when you place the speaker "square" into a round mounting location, (for the non-oval types) the tweeter will face up into the cabin, it will drill a beaming hole across the cabin above the other speaker by the amount of angle it's set at.
so, you have the mid cone beaming into the cabin on a vertical, directly across at higher frequencies, and this little tweeter beam, shooting into the window across.
turn the speaker to the right, (driver side) and the angle on the tweeter is now pointing into the windshield, or opposite dash.
turn the speaker left, and the tweeter is pointed towards the passenger's head, a little more and.. well, it's an arc of directivity. You turn the speaker, and the tweeter will follow this arc so that you can make the wavefront of the midrange and the tweeter coincide.
it's not that intuitive, you have to picture it in position and it's hard to make ad copy out of, but it's a design technique that used correctly, pays off big, especially since the whole complication of designing a passive is simplified to the one-case scenario.
You literally can simplify the crossover's schematic and element count, based on the known quantity of where the tweeter is going to be firing from.
This naturally, only works well in positions where obstructions are not an issue, like above the knees in the doors.
I imagine it also would work in a way, to reduce reflection issues in a 4" braxial in the A-pillars, by turning the mounted speaker so the tweeter's angle is focused optimally away from near-surface reflection areas.
You don't see this kind of speaker much anymore, I think. It's different from a bayonet, or post mounted tweeter that's angled, in that the braxial design gives you an adjustment range by rotation, for both time-aligning and what I'm saying here, pattern or directivity control.
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Re: Frequency humps and dips
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Re: Frequency humps and dips
Quote:
Originally Posted by
claydo
looks like the left side is about 30 degrees or more off axis... :P
Sent from my Lumia 920 using Tapatalk
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Re: Frequency humps and dips
claydo,
How's that working in an automobile ? You happy with the sound ? Have you heard anything that sounded better ?
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Re: Frequency humps and dips
Quote:
Originally Posted by
WOOSEY
looks like the left side is about 30 degrees or more off axis... :P
Sent from my Lumia 920 using Tapatalk
Aww, picky picky.......but yea, they are actually are aimed to cross at about 6" in front of the right side of your head......if ya want to get all technical!:nana:
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Re: Frequency humps and dips
Quote:
Originally Posted by
Hic
claydo,
How's that working in an automobile ? You happy with the sound ? Have you heard anything that sounded better ?
Its working great hic, its by far the best I've ever had. The width is good, height good, biggest challenge has been depth.......not the front of the stage depth, its right on the windshield, but getting it to extend out past the Hood has been a challenge......the best thing about it is the adjustable nature of the mounting system, I've been amazed several times at the improvements I've made with slight angle adjustments, that has really helped the tuning come a long way, and as you know most speaker installations are fixed......once installed you have what you have......with these I have a shimming method for toe in, toe out....and probably 30° or more in up down angle........I can't begin to tell you how much that has helped. Yes, I've heard technically better, more pleasing to me?.......nope....
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Re: Frequency humps and dips
Quote:
Originally Posted by
Hic
claydo,
How's that working in an automobile ? You happy with the sound ? Have you heard anything that sounded better ?
I can attest that it works very well in Clays vehicle. The only thing that setups like this consistently lack (IME) is stage width on the left side. It's very hard to achieve a wide balanced stage with this setup. But center image and tonality can be extremely good and Clay has done an excellent job of that in his install/tuning.
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Re: Frequency humps and dips
Well, my thanks doesent seem to be working........ so ill just say it, thanks capn!
Ok, came back later and now its working. Good, that makes it all official!
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Re: Frequency humps and dips
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Originally Posted by
captainobvious
The only thing that setups like this consistently lack (IME) is stage width on the left side..
I've actually found the opposite to be the case. My width actually increased all around.
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Re: Frequency humps and dips
The only thing in this car I have to compare it to is two way in the doors and tweets off axis in the sails. Its definately wider than that was. In my current setup my drivers side stage is beyond the drivers.....but with that big freaking pod in yer face, the visual cues are hard to ignore........when ya close the ol eyes, or at night the image swells substantially.......:thumbup:
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tuning/judging should be done with your eyes closed as much as possible
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Re: Frequency humps and dips
Quote:
Originally Posted by
erinh
I've actually found the opposite to be the case. My width actually increased all around.
Not everyone can run full range subwoofers in their a-pillars.
Sent from my Springfield XD with love!
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Re: Frequency humps and dips
http://i1360.photobucket.com/albums/...ps4fe80e97.jpg
Subwoofer! :snap:Actually, iirc he crosses these over to the jl's lower than I do my 4"s.
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Quote:
Originally Posted by
Fricasseekid
Not everyone can run full range subwoofers in their a-pillars.
Sent from my Springfield XD with love!
What clay said. I cross the 5's at 350hz. That's higher than most folks cross their 3's. ;)
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Dammit, made me read back.......I said lower, meant higher......looks to be too late for an edit!
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I abuse my poor little 4s down to 160! @ 18 DB!
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Re: Frequency humps and dips
I'm sure that cone area has something to do with your amazing width.
Sent from my Springfield XD with love!
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Re: Frequency humps and dips
Quote:
Originally Posted by
Fricasseekid
I'm sure that cone area has something to do with your amazing width.
Sent from my Springfield XD with love!
I've had speakers in that location for the past few years. And they weren't all 5's.
Who said "amazing" anyway? Not me. No need to be snarky dude.