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Discussion Starter #1
I've noticed that many people are doing a 3 way setup with a midrange in a custom made kickpanel. My question to you is, why don't people have tweeters in the A-pillars and the kicks. Wouldn't it sound better? Have a normal 3 way setup but add an extra pair of tweeters to the kicks. I have seen few SQ cars do this. Any ideas?
 

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Usually the tweets in the kicks are the primary ones, with the tweets in the pillar primarily used to raise the soundstage.
 

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If they are used in the same frequency band, it would most likely cause phaseshifting and worse soundstage.

If crossed quite high, like 10 000 hz, they would not interfere quite as much, as the ears are most direction sensitive in the midrange area. Therefore you can accomplish a higher soundstage despite having most of the speakers in the kickpanel :)
 

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Correct me if I'm wrong here, but isn't the main reason for keeping your speakers low in the kick panel area to keep your path lengths as equal as possible? If positioned correctly, tweets and mids in the kicks will give you a great sound stage.
 

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Also, there's no need for several tweeters because they tend to be much more efficient than mids. What I mean is, If your mid is 87 db sensitive and your tweet is 91 db sensitive, you have a 4 db discrepensy. So, you can run 80 watts rms to your mids and 40 to your tweets and they should come out sounding about equal. Now imagine you've got two pairs of tweeters. That's an extra six db for the second speaker running in the same frequency range. So, you'd need to cut you're power in half two more times to even it out. That would be roughly 10 wrms to the two pairs of tweeters to be equal to your one pair of mids with 80 wrms. This is why you typically see twice as many mids as tweets. Well, part of the reason. It's much deeper than that, but you get the idea. I'm a little tired so my math may be a touch off. But it shouldn't be by much. Let's see, 80 wrms would give a gain of about 20 db. I said the mid was 87 db sensitive so that's roughly 107 db over all. Now, two pairs of tweets at 91 db sensitive would yield 97 db at 1 wrms. So to get 107 db to match the mid, you'd need 10 more db. That's about 10 wrms. so yeah, that works out.
 

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From what I remember from past studying, based on cutoff frequencies, there's a certain distance one speaker should be from another. If you cut off a mid at 2k and a tweet at 4k, you'd take the quarter wave length or half wave length, I forget which, and that's the distance apart the two speakers should be. Each frequency has a different wave length. The higher the frequency, the shorter the wave length, the closer the speakers should be to each other. Tweets and mid ranges should be closer than the midrange to the mid base, etc. It's really based on your cross overs though. I forget the actual math to it. If I wasn't so tired, I'd look it up. I think it was covered in the loudspeaker design cookbook.
 

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so in my case ( mids /tweets) in the pillars

how does one overcome path length differences

as kicks are not a option since

#1 the distance from kick panel to ear is over 60" or so

#2 the foot pedal is so close to the driver kick such that I cant really aim the drivers side at all


nice explanation by the way
 

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Wow airforce, thats some good knowledge your tossing about. I think the general rule of thumb is to have the tweet within 18" of your mid...
 

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in order to equal out your path lenghs with the tweets so high up, you'd have to use a signal processor to delay one channel. I'm sure there's others on this post who can help you correct that issue better than me. The speed of sound is approximately 1129 fps. Divide that by 3khz, you get about .38 feet, or roughly 4.5" So, two speakers with a xover giving them a 6db downpoint at 3khz should be approximately 4.5" apart. I think that's how that worked. To estimate the time delay from one side to the other, You'd want to measure the distance from your head to each speaker. With the speed of sound being about 1129 fps, take the difference between the two distances (in feet, i.e. 1.5) and divide it by 1129. That would be about the amount of delay you'd want on the speaker closest to you. Drivers side. For example, lets say there was about 2.5 feet of difference in the distances. 2.5 divided by 1129 is about .002 or 2 miliseconds. It sounds trivial, but when you're going for perfection, every little bit counts. That's it for me, I'm going to bed. Thanks for the challenging conversation. I'll keep checking back for new posts, if you want hit me up on me e-mail too. I'm off to the desert in Jan. Hopefully I'll still be able to get on the boards from there. Peace out.
 

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So Say i have a midrange and tweet mounted in a set of Apillars, Right now looking at the Hivi DMA for midrange and i have the LPG 26 already in my pillars. The Hivi will be mounted just under and a little towards the windshield with respect to the tweeter, mabey 2-3" away from tweet center.

The midrange can only go down to around 1k, Not as low as i'd hoped, but still not completely sure on midrange, i'd rather have it go down to 500hz or so. But Midbass would xover at that point down in my stock Door locations and down to around 63hz. Would there be any need for TA...as i'm trying to get away from using TA at all. And still have a very nice sound, with very good imaging and such.

Right now i have no TA on my tweeters and they sound VERY nice, but i have TA on my midbasses, as they go up to 3k, but placing a midrange with the tweets would i need to TA to get very good dash imaging? Or would this placement still need TA to get proper imaging......

This is hopefully going to sound nice for both front seats, not just driver.
 

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demon2091tb said:
How would Tweets in apillars, midrange in kicks, and midbass in doors do?

Believe it or not this is a common setup. The key to making this setup work is the find a midrange that will play atleast 6khz and up. Now for the door mounted midbass I would start like this. First measure from door to door the find out how wide the car is, lets say it is 2 meters wide. Now divide the speed of sound (330 meters per-second) by that which will give you 165, 165 hz is the highest you should run your door mounted midbass so that is dosn't affect your staging and imaging.

Here is some very good reading from Mark Elderidge

..........................................................................

The real skivvy is that you want to minimize the differences, for a lot of reasons. Especially in the mid-bass through the midrange regions, the difference between left and right pathlengths is CRITICAL! In fact, between 100 and 400 Hz, the angle of the speaker won't even matter, as imaging cues are almost 100% determined by path length, not by intensity differences. Above 2000 Hz, imaging cues can be controlled by speaker angle and other intensity controlling techniques. Path lengths above 2000 Hz are not critical.

As far as the path length differences between the mid-bass driver, midrange, adn tweeter on a single side, you'll probably never get them exactly the same. The real problems with path length differences here will be int eh frequency and phase response in the crossover range. Signal alignment can help some here, as long as the speakers aren't too far from each other. It's more acceptable to have a mid-bass amd midrange separated than to separate the mid and tweeter. The mid-bass frequency range can make a difference in the perceived stage depth,a dn the center image stability. But, the upper midrange and high frequencies are responsible for the stage height, width, and depth, as well as image focus. Keeping these frequency range drivers close together will be a lot easier to control all the variables than separating them. If you need additional stage height because the mid and tweeter are in the kick panel area, then add a second set of tweeters high and wide, and crossed over pretty high as well (somewhere between 8000 and 20000 Hz). This configuration is what has been used in most all fo the best sounding cars that use conventional drivers. And in most of the HLCD systems, the additional tweeters are used for the same reason.

Anyway, locate the midrange drivers first, and work with them in their intended frequency range to achieve the best overall stage depth and center image. Don't worry too much about stage height or width yet.

Next, locat the mid-bass drivers so they blend well with the mids, have solid output, and do not detract from the center image. Doors will likely not be the best place for them. They can be mounted under the dash, in the floor, in the firewall towards the center of the car from the kick panel, or where ever else they work, adn can have a large enough enclosure.

The tweeters are the easiest. Mount them as close to the mids as possible, and make sure they give you the width and height you want, and help to focus the image performance. If you need the additional height, add the second set of tweeters.

Path lengths are a different animal. They're kind of like the impedance of a woofer. Industry wide, we call a speaker a "4 ohm" or "2 ohm" speaker, when in reality, it is only really that impedance at one or maybe two frequencies. That's the "nominal" impedance which means "in name only." The actual impedance varies widely accoring to frequency. A "4 ohm" speaker in a box may have impedances as high as 50 ohms at resonance, and as low as 3 ohms elsewhere.

Likewise, the sonic cues that affect what we percieve as staging and imaging are frequency dependent, and there is no one single number, technique, or what ever that can be used across the frequency board.

Good luck!

--------------------
Mark Eldridge
Mobile Soundstage Engineering
[email protected]
 

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MY god, Thanks alot. That was incredible.

Now when you talk about the highest a midbass should be played, dependant on car width, as your example was 165hz, Is this for a centered image, or what? I have my CA18's playing from 63hz up to 3khz and i have no problems with the midbass range you speak of. But is this specifically for say the 3way setup i was referring to? With respect to your example, there is no midrange that can go down that low....to 165hz, what would you do in this case.

I am trying to locate some info right now on the DLS IR3 dome midrange, as alot of people seem to swear by it, and it can go fairly low....(actively being used by many people down to 350hz), so that looks like my best bet, if it isint expensive (which i doubt).

When you say pathlengths are critical for the midrange region. This is why many people mount there midranges in there kicks, not because its at there feet (throws me off how they can still get a dash image being so low) but to get equal PLD's. I can see why people mount them down there for PLD but how does psychoacoustics go into play by not noticing that the drivers are down in the kicks, yet sound radiates from above the dash? Where would be the proper place to aim these kick drivers? (If i go this route, i will simply cutt into my panels, stiffen them up ALOT and place the dome in the panel) Then re-tune the car. Then i would have the problem that Midrange would be in the kicks, closer to midbass, probobly 1'-1.5' And farthest away from tweet, up in A-pillars a good 2-3' above it. How would you get them to blend rather good? Without having 2 different sets of tweets for main tweets in kicks and an upstage kit?

Sorry for so many questions....I really think that explination needs to be put into the DIY Tutorials....As a sticky.

BTW anyone know where to get just a pair of DLS IR3, not the whole 6.3 or 8.3 setup? For really cheap?
 

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demon2091tb said:
MY god, Thanks alot. That was incredible.

Now when you talk about the highest a midbass should be played, dependant on car width, as your example was 165hz, Is this for a centered image, or what? I have my CA18's playing from 63hz up to 3khz and i have no problems with the midbass range you speak of. But is this specifically for say the 3way setup i was referring to? With respect to your example, there is no midrange that can go down that low....to 165hz, what would you do in this case.

You are correct, this is the get a stable center image, but this is from both seats. You are also correct it aplies to the 3 way setup.

There are a few midranges to can play the low and high. Right off the top of my head all of the MB Quart QSD drivers can do it. Well the 4 and the 6.5 can. I think the 5.25 falls I a little short on the top end. The QSD165 plays for like 50hz up to 7khz and the $" fron like 80hz up to like 8khz.


I am trying to locate some info right now on the DLS IR3 dome midrange, as alot of people seem to swear by it, and it can go fairly low....(actively being used by many people down to 350hz), so that looks like my best bet, if it isn’t expensive (which i doubt).

I to really like the IR3. It is on of the easiest driver to work with as far as setup up for good staging and imaging. It does take a little more tuning to dail it in. It will play down to 315 nicly with a steep crossover slop. I can get them being the only DLS dealer in Miami, but as you said it is not the cheapest dome to buy. $210.00 plus shipping.

demon2091tb said:
When you say pathlengths are critical for the midrange region. This is why many people mount there midranges in there kicks, not because its at there feet (throws me off how they can still get a dash image being so low) but to get equal PLD's. I can see why people mount them down there for PLD but how does psychoacoustics go into play by not noticing that the drivers are down in the kicks, yet sound radiates from above the dash? Where would be the proper place to aim these kick drivers?
Man you are put my brain on overload. On the psychoacoustic thing it has something to do with the way our brain processes sound. Not by location, but by distance. Not being and Acoustic Engineer I’m hurting myself here. Someone help me out here. I have to info somewhere; I will have to dig it up.

On aiming the drivers, this is where all the work comes in. there is no set angle to use. You will have to play with the angle the get the best possible staging and imaging. I good starting point is aim them around 3 to 4 inches in the front of the listener on the opposite side at eye level and work from there. Now back the IR3, it is one of the easiest driver to get this done with. I a lot of cases you can mount them flat in the kicks or nearly flat and get great staging and imaging.

demon2091tb said:
(If i go this route, i will simply cutt into my panels, stiffen them up ALOT and place the dome in the panel) Then re-tune the car. Then i would have the problem that Midrange would be in the kicks, closer to midbass, probobly 1'-1.5' And farthest away from tweet, up in A-pillars a good 2-3' above it. How would you get them to blend rather good? Without having 2 different sets of tweets for main tweets in kicks and an upstage kit?

Sorry for so many questions....I really think that explination needs to be put into the DIY Tutorials....As a sticky.

BTW anyone know where to get just a pair of DLS IR3, not the whole 6.3 or 8.3 setup? For really cheap?
With a dome midrange that may be possible, but with a cone driver its not that easy. Even with the dome I would still play with the angles.

On the distance between the midrange and tweeter, that is where finding a midrange that can play up to at least 6khz. Far as the blending of the drivers it goes back to the thing about, above 2khz PLD is not very important. It is also about choose good crossover settings and slopes.

The way I see it you can never ask to many question, how else are we going to learn. I know I have ask a ton in my time and will be asking a ton more. The key is to take the newly found knowledge and go out the try it in a real world setup. Having the knowledge does us not good it you can make use it or should I say employ it. As we in the Army or has been in the Army say, to be great at any given trade you MUST BE BOTH TECHICAL AND TACTICAL PROFICIENT.

Here is some more good reading from Mark Elderidge. Just remember most of this info is for obtaining great staging and imaging from both seats. It is not as hard to obtain great staging and imaging from one seat. If you one seat wonder is what you are looking for.


……………………………………………………………………………………..

To get loud, low midbass, you'll most likely need to install in the door as most high output midbasses are designed for IB applications. So then, because pathlenght differences cause problems above 100 HZ, these door mounted midbasses must, as a rule, run between 50 or 60 Hz up to 100 Hz, with lots of power.

Challenge now becomes to find a midrange driver that plays clean down to 100 HZ and up to as high as 5500 to 6500 Hz (if tweeters are A-pillar mounted).

It looks more and more like a 4-way front setup if you want loud low midbass and A-pillar mounted tweets, like this:

A-pillar tweet: around 6000 Hz and up.
Mid : 400 Hz to 5000-6000 Hz optimize the pathlenght & angle. I would use a 4- inch mid.
Mid Bass: 100 Hz - 400 Hz optimize pathlenght, angle is not as important. Maybe a 6 inch bass driver.
Bass : Door mount IB 50 - 100 Hz. Pathlenght not as important under 100 Hz. I would use an 8 inch shallow mount designed for high output IB enclosure.
Subbass: Below 50 or 60 Hz.


Lots and lots of variables to consider..........

Remember, below 400 Hz, down to around 100 Hz, imaging is 100% pathlength (or arrival time) dependent. So, having your midbass drivers in the doors, creating a big path length difference between left and right, is causing a lot of the problems.

If you get the system so that it images better and has a smooth spectral response in this frequency range, more than likely, you'll be able to bring the overall apparent stage height up also. Poor spectral response and imaging qualities can draw a lot of attention to areas you don't want to stand out.

Can you mount the midbass drivers just inside the kicks in the floor? Maybe with a heavy, non-resonant grille to protect them? Talk about eliminating path length differences.....

The horns and 8's might work. But, an 8 that can keep up with the high sensitivity of a horn usually will not play much below 50 Hz at best. Better plan on a sub too.

--------------------
Mark Eldridge
Mobile Soundstage Engineering
[email protected]
Team JBL Member 002
 

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Thanks again, IS there any cheaper place to get the DLS IR3? Is 210 for a pair or just for one?

Any info on the Dyn MD140/2, hopefully its just as good, with a much lower price.
 

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210 is for the pair. Let me see what I can do, I might be able to give a slightly better deal.
 

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demon2091tb said:
Thanks again, IS there any cheaper place to get the DLS IR3? Is 210 for a pair or just for one?

Any info on the Dyn MD140/2, hopefully its just as good, with a much lower price.
I don think the Dyns will be any cheaper, if not more expensive....
 

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Discussion Starter #19
Wouldn't crossing over a tweet at such high levels such as 8khz or 20khz be damaging to a tweeter? I would think that most tweeters would hiss or have several problems between these frequencies.

Also, I guess you could have 2 sets of tweeters after all. I could have my Focal 4w2 in the kick with a good sounding tweeter and then find the perfect tweeter to crossover at these high frequenices in excess of 10khz for my doors. Team that up with a custom crossover and good midbass driver and I'll be all set up. Any ideas on a tweeter that can crossover this high or can do most of this.
 

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atomicquad said:
Wouldn't crossing over a tweet at such high levels such as 8khz or 20khz be damaging to a tweeter? I would think that most tweeters would hiss or have several problems between these frequencies.
if they have hiss or several problems between those frequencies....


they are going to have them no matter where they are crossed over :)
 
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