# best location for rear fill, rear door or rear deck



## matthewo (Jan 31, 2008)

well, i want to put a small amount of rear fill, which will be T/A. i have my rear door location and my rear deck location. the rear door will take up to like 6" speakers, 6.5 wont fit. the rear deck will take up to 8" speakers. whats the best place. i was thinking the rear deck because i can get a better sound stage by bouncing off the rear glass. the rear door speakers basically fire into the front seats and are way off axis. what about a 5 1/4 component set in the rear deck location and i make a 8" baffle which holds the tweeter and midbass, i guess i could probably even fit a 6 1/2 and tweeter in there.


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## 89grand (Nov 23, 2006)

I would use the rear deck. The rear door locations are useless except for people in the back seat.


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## unpredictableacts (Aug 16, 2006)

I am going to go with up front.


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## matthewo (Jan 31, 2008)

unpredictableacts said:


> I am going to go with up front.


so you dont like rear fill is what your saying...., i already have some up front


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## unpredictableacts (Aug 16, 2006)

matthewo said:


> so you dont like rear fill is what your saying...., i already have some up front


honestly I do not, but I have heard some older set ups using a slight volumed rear fill pretty successfully......only for rear fill if that makes sense.


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## ealvar (Mar 9, 2007)

I'm in the same boat as unpredictableacts.

I've tried rear fill in a number of installs and it just never really worked all that great.

The most successful was a set of Image Dynamics IDQ5 mid-bass drivers in the rear deck of an '03 Mustang.

I've found that in the rear doors, or even in rear pillars of a GMC Sierra extended cab, the improvement in sound is negligible and never worth the money or the amplifier power.

In my last few rides I just fade out the stock speakers and concentrate on having a good front stage.


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## freemind (Sep 11, 2008)

Left in the box at the store.

Thats my story and I'm sticking with it!


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## Candisa (Sep 15, 2007)

If you want to try rear-fill:
- use the rear-deck locations
- use 5.25" midwoofers
- bandpass 200-3000Hz (too low will ruine coupling between sub and front midbasswoofers, too high will pull the stage to the rear)
- if possible, send them L-R and R-L signal instead of just stereo signal.
- add a fair amount of time delay


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## 89grand (Nov 23, 2006)

I used to think I hated rear fill, but I've since changed my mind. It _can_ be very useful for getting a better center image and for stage width.


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## matthewo (Jan 31, 2008)

i have yet to tune my system as far as t/a goes and eq but it just doesnt seem like i get full enough sound at low volumes. and i think the rear fill would help a little. so does anyone else think tweeters are a no no for rear fill? so 200-3000hz would be the best with a pretty good quality full range driver


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## matthewo (Jan 31, 2008)

and when you measure time delay for the rear deck, it would be distance to the glass from speaker + distance to the driver ear from location the speaker hits on the rear glass?


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## 89grand (Nov 23, 2006)

I don't know. My rear speakers are running full range, and I don't have a problem with the imaging being pulled to the rear. My car is a Magnum so my rear speakers are further back than most cars, and they obviously don't fire off the back glass so that probably helps a lot in my situation.


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## 89grand (Nov 23, 2006)

matthewo said:


> and when you measure time delay for the rear deck, it would be distance to the glass from speaker + distance to the driver ear from location the speaker hits on the rear glass?


Just measure the distance from the speaker to your ear.


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## VP Electricity (Apr 11, 2009)

89grand said:


> I would use the rear deck. The rear door locations are useless except for people in the back seat.


Exactly why I would use the rear door. I also go tweeterless when I can.


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## I800C0LLECT (Jan 26, 2009)

http://www.diymobileaudio.com/forum/diy-mobile-audio/22523-hey-werewolf-confusion-about-l-r.html


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## 14642 (May 19, 2008)

If you have TA for the rear, add 12-20mS of delay. Then you won't have to woffy about L-R and all that stuff so much.


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## 89grand (Nov 23, 2006)

VP Electricity said:


> Exactly why I would use the rear door. I also go tweeterless when I can.


The only thing that concerns me about the rear doors is that they are so much closer to the listening position. Maybe it works, I've never tried it, it just seems like it wouldn't add much depth being mounted down low and that close, but maybe it does.


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## Candisa (Sep 15, 2007)

The whole point of rear-fill is create the illusion you are in a larger environment by sending fake back-wall reflections to the ear. The best way to do that is to put the rear-fill-speakers as far as possible to the back of the listening invironment --> in a car, that's the rear-deck.


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## jsun_g (Jun 12, 2008)

Agree with this approach, at least it worked well for me in the past. I had an old MTX RTX-03 active crossover which actually had a bandpassed L-R output. The sound sucks for the rear seat passengers though 

I am going to try L-R again in my current install. I also have an Alesis processor that does some neat effects plus time delay that I plan to try.

I like the rear deck location because there are more surfaces (namely the back/hatch glass) for sound to bounce off of for more "ambience".




Candisa said:


> If you want to try rear-fill:
> - use the rear-deck locations
> - use 5.25" midwoofers
> - bandpass 200-3000Hz (too low will ruine coupling between sub and front midbasswoofers, too high will pull the stage to the rear)
> ...


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## gijoe (Mar 25, 2008)

VP Electricity said:


> Exactly why I would use the rear door. I also go tweeterless when I can.


I would use the rear doors too, and if I can ever figure out a way to do a proper delayed L-R signal I'll try it.

The higher frequencies pull the stage back, which is bad for rear fill. Tweeters would be a no no in my opinion. The reason that I like the doors is because the seat will act as a bit of a filter for the high frequencies, for the front seat positions. If you have the speakers in the rear deck the high frequencies will reflect and pull the stage back.


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## Candisa (Sep 15, 2007)

Filtering frequencies is why some smart person invented the crossover network...


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## gijoe (Mar 25, 2008)

Candisa said:


> Filtering frequencies is why some smart person invented the crossover network...


Well unless you have the processor to run rear fill the right way, I don't think you will have this crossover network. My advise was intended to apply to a situation where rear fill is desired and the proper processing isn't available.

Mounting speakers low in the rear doors, behind the seats can help cut some of the high frequencies out of the equation.

Am I missinterpreting your posts or do you really intend to come off as a smart ass? I understand it can be difficult to interpret the tone of the written word, but i don't get the impression you are playing very nicely.


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## ealvar (Mar 9, 2007)

gijoe said:


> Well unless you have the processor to run rear fill the right way, I don't think you will have this crossover network. My advise was intended to apply to a situation where rear fill is desired and the proper processing isn't available.
> 
> Mounting speakers low in the rear doors, behind the seats can help cut some of the high frequencies out of the equation.
> 
> Am I missinterpreting your posts or do you really intend to come off as a smart ass? I understand it can be difficult to interpret the tone of the written word, but i don't get the impression you are playing very nicely.


Candisa's analysis is right on.

If you don't have the equipment, time, and money to do rear fill right it's better just to leave it out.

Doing it correctly requires proper signal processing, period.

Without processing, in most situations, you're simply moving your sound stage back which usually is a bad thing.

Rear fill is not like having rear speakers in a home theater surround system.

I really don't think Candisa was trying to be a smartass... blunt, maybe.


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## monkeyboy (Jun 12, 2007)

I'd say she's getting a little irritated. She is giving the ideal answer. You want to do something this way, and this is how you would get there. This is what the OP seems to be asking for.

Others seem to be coming in and saying other things that don't agree with what she is stating because they do not have the equipment to do such, but nothing is said about that until they are questioned about it. It is misleading even if it is intentional, and can be irritating if you have given the right answer, and people are throwing out wrong answers without any explanation as to why they work like she has.

BTW. I will be running rear fill, just as she has suggested. I have the processing power


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## gijoe (Mar 25, 2008)

ealvar said:


> Candisa's analysis is right on.
> 
> If you don't have the equipment, time, and money to do rear fill right it's better just to leave it out.
> 
> ...



I would agree that if you don't have the processing to do it right, you shouldn't do it. That's why I don't run rear fill.

But, I get the impression from the OP that he plans to do it anyway. My suggestion was my opinion to make the best of a potentially bad idea. If the OP is set on rear speakers, I think the best place for them is low in the rear doors to use the seats as filters.

I know Candisa knows her stuff. I was just trying to offer my suggestion to the OP if he/she is set on running rears, I think the rear deck will be a bad idea. In a proper rear fill setup, I don't disagree with her at all.


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## ealvar (Mar 9, 2007)

The key thing to remember here is the human auditory system's ability to localize sound (tell where the sound is originating).

The higher the frequency, the easier it is for us humans to localize sounds.

With proper sound processing (typically delay and crossing over at frequencies below the human sound localization threshhold) rear fill will enhance the listening experience.

Without proper sound processing... well, it's been stated here several times... it just sounds bad.

There are a ton of good articles regarding sound localization.

Another factor is binaural localization vs monaural localization. The human ear is better equipped to localize binaural sound than monaural.


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## ealvar (Mar 9, 2007)

gijoe said:


> I would agree that if you don't have the processing to do it right, you shouldn't do it. That's why I don't run rear fill.
> 
> But, I get the impression from the OP that he plans to do it anyway. My suggestion was my opinion to make the best of a potentially bad idea. If the OP is set on rear speakers, I think the best place for them is low in the rear doors to use the seats as filters.
> 
> I know Candisa knows her stuff. I was just trying to offer my suggestion to the OP if he/she is set on running rears, I think the rear deck will be a bad idea. In a proper rear fill setup, I don't disagree with her at all.


I think we all agree


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## jsun_g (Jun 12, 2008)

There is a major reason why I don't like the rear doors for fill, and it is this:

the person sitting in one of the front seats (take your pick) may have a more or less direct path between their inside facing ear and the rear speaker in the opposite side door, especially if the mounting location is closer to the rear of the car. When I sit in a vehicle like that as a front seat passenger, the music coming from the left side seems to be coming from the driver's headrest instead of from on top of the dash. Even after attenuating the rear fill volume, there was a bias from the opposite-side rear speaker that pulled the sound stage back.




gijoe said:


> I would use the rear doors too, and if I can ever figure out a way to do a proper delayed L-R signal I'll try it.
> 
> The higher frequencies pull the stage back, which is bad for rear fill. Tweeters would be a no no in my opinion. The reason that I like the doors is because the seat will act as a bit of a filter for the high frequencies, for the front seat positions. If you have the speakers in the rear deck the high frequencies will reflect and pull the stage back.


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## gijoe (Mar 25, 2008)

jsun_g said:


> There is a major reason why I don't like the rear doors for fill, and it is this:
> 
> the person sitting in one of the front seats (take your pick) may have a more or less direct path between their inside facing ear and the rear speaker in the opposite side door, especially if the mounting location is closer to the rear of the car. When I sit in a vehicle like that as a front seat passenger, the music coming from the left side seems to be coming from the driver's headrest instead of from on top of the dash. Even after attenuating the rear fill volume, there was a bias from the opposite-side rear speaker that pulled the sound stage back.


It's a give and take. You can put the speakers in the rear deck, but then you have the problem with the high frequencies reflecting off the glass at head level. That will pull your sound stage back. I suppose, since you are set on using rear speakers (i wouldn't) try both area's and see which works best.


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## Candisa (Sep 15, 2007)

gijoe said:


> Am I missinterpreting your posts or do you really intend to come off as a smart ass? I understand it can be difficult to interpret the tone of the written word, but i don't get the impression you are playing very nicely.


That's just my way of speaking, call it European bluntness


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## gijoe (Mar 25, 2008)

Candisa said:


> That's just my way of speaking, call it European bluntness


Haha fair enough!


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## enerlevel (Jun 6, 2009)

i feel there should be a little rear fill...... it helps in getting a little depth to mid bass. but then , if u dont have rear fill at the deck , u could use them as air ports for the bass to come in ......


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## matthewo (Jan 31, 2008)

i think i have enough processing power to pull it off. audison bitone.1 will be doing the processing and 2 channels will be dedicated to rear fill. so eq, crossovers and time delays will be possible.


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## matthewo (Jan 31, 2008)

also im leaning towards the rear doors to keep the subwoofer distortion away from the speakers. i have a trunk setup, well actually the sub fires into the cabin, but some bass might travel to the rear deck speakers and distort them...


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## gijoe (Mar 25, 2008)

matthewo said:


> also im leaning towards the rear doors to keep the subwoofer distortion away from the speakers. i have a trunk setup, well actually the sub fires into the cabin, but some bass might travel to the rear deck speakers and distort them...


The classic Violent Bass Air! 

Well, it sounds like you have more processing capabilities than I previously thought. If you can delay the rears and cut out the higher frequencies, go for it! You could always use the rear deck, like Candisa suggested, and build enclosures to isolate the speakers from the subs.


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