Does this exist? Help

[dopey 0]

First, a little about my setup.

I want to run a 4 channel amp on my front stage, a two channel on rear fill, and 2 sub amps.

This means I need 4 sets of preamp outs right? One set for front tweets, one set for front mids, one set for rear full range, and one set for sub amps.

I want to be able to cross over the front mids and tweets at different points, in case I change components. I feel it sounds better if this is done at the HU so the amplifier can concentrate power only on desired frequencys.

I will only use the preamps, so internal amp isn't necessary, infact I'd prefer NO internal amplifier.

Only need CD capability, no MP3, no DVD.

Some sort of time alignment.

Thanks.

[///M5 2,833]

Boo rear fill.

Clarion DRZ9255 and the Ural are pretty much your options for having all of that in the headunit. Do check and see if you can run the bandpass for the midbass full range for your rear fill though. I have never heard of anyone trying that and don't understand but they should be the only two that can really do it.

[dopey 0]

Thanks. If the car wasn't a four door, I wouldn't even worry about it. I usually keep the rear gains just above inaudible. It helps submersion in the sound. Just to tie everything all together.

[ngsm13 1]

Boo rear fill.

Clarion DRZ9255 and the Ural are pretty much your options for having all of that in the headunit. Do check and see if you can run the bandpass for the midbass full range for your rear fill though. I have never heard of anyone trying that and don't understand but they should be the only two that can really do it.

Beat me to it sir.

Good luck on the Ural CDD.

nG

[///M5 2,833]

Thanks. If the car wasn't a four door, I wouldn't even worry about it. I usually keep the rear gains just above inaudible. It helps submersion in the sound. Just to tie everything all together.

Stage killer.

[bigger_george 2]

I have the clarion drz9255. It'll work great but midrange only has a xover that goes down to like 500 hz, so u may hafta use the crossover on your amp to bandpass your front stage. I didn't even know the Ural was ever available here.

[dopey 0]

Search isn't turning up anything on URAL...well nothing I can read. Getting some neat cryllic crap.

If the front stage gets mushy...the rear is too loud.

I'm talking JUST above inaudible. If youre in the back seat...you can't hear it. I can hear it because I know it's there. hey jizzboy, see your way out. youre not welcome in my threads.

[ngsm13 1]

I hope you NEVER come to CA.COM

With a properly setup front stage, rear fill is not needed. AT ALL.

nG

[DevilDriver 28]

Ok, let's think about this for a few moments. First, let's try to avoid telling someone that they're not welcome in any threads. Take the advice given or discard it: it's your choice. At the same time, we want to try and keep things friendly here, so if you have an issue with any member, it's probably better to hash that out in pm's, mmmkay?

Now on to the fun part...

First, let's define what we mean by "rear fill". In a traditional sense, this would be a set of speakers in the rear of the vehicle that cover all frequencies already predominantly handled by your front stage. A more current definition seems to be any set of speakers in the rear of the vehicle, whether this be handled by a highpass, lowpass, bandpass, or allpass filter. It's safe to say that everyone who has posted in the thread is relatively familiar with both sides of the coin, but I'll mention it for a moment anyways.

I'll be very clear in saying that I never, ever, ever use rear fill. As an engineering student, everything I do is based on the laws of physics. The concept, if you're not familiar with it, is that of constructive and destructive interference. Constructive interference occurs when two interacting waves at a given frequency result in an increased amplitude at any point in the period we are analyzing. Destructive interference is just the opposite: the interaction of the two (or more; this can be an infinite number) of waves results in a decreased amplitude. These increases and decreases is a result of the phase of each wave. If the coinciding waves are in phase, we will experience an increase in amplitude. If the coinciding waves are out of phase, we will experience a decrease in amplitude. Perhaps a visual will help here. The example on the left shows two waves, in phase on the bottom, and their summation above. The example on the left shows two waves, out of phase on the bottom, and their summation above.

So how is this relevant in a vehicle? Quite simple. Assume speaker A and speaker B are wired identically. From a relative phase standpoint, they are in phase. That's great. But what if these speakers are placed in areas that make them not equidistant to each other? Let's assume for a moment that speaker A is 2.5 feet away from your ear and speaker B is 3 feet away from your ear. Let's assume each speaker plays a 1000 Hz sinusoidal wave. To complete one period (or one full wavelength), the sound pressure from each speaker must travel approximately 1.2 feet. Speaker A will complete approximately 2 full periods (2.5/1.2=2.08). Speaker B will complete approximately 2.5 periods (3/1.2=2.5). At this point, the speakers are in fact, out of phase, in an absolute sense. Here, we're experiencing destructive interference. Simply put, we're seeing nulls in our frequency response that shouldn't be there. This just isn't a good thing.

But it's much worse than that! Sound is directional and gives directional cues. A speaker in the rear sounds like a speaker in the rear, believe it or not. It will undoubtedly pull your sound stage rearward, which is never a good thing from a matter of accurately reproducing music. But...

There are in fact logical and understandable reasons for using "rear fill", no matter what our definition of this is. When was the last time you could easily fit a large format midbass driver with considerable output in your kickpanels or doors? A little discussed fact is that high midbass output down to 40-50 Hz is one of the big differences between award winning sq vehicles and "also-rans". In fact, you'll find this fact to be demonstrated frequently throughout car audio history. Richard Clark's Buick Grand National had midbass in the rear. Harry Kimura's best sounding vehicles have had rear midbass; in fact, almost all of the best sounding Speaker Works vehicles have had midbass in the rear. There is in fact, empirical evidence that midbass in the rear works because the directional sacrifices that are made are overcome by the presence and output of the midbass. This is just one legitimate reason.

Second, any rear passengers in a car will have a very hard time experiencing the front sound stage that you worked so hard to perfect. The vehicle is a horrible listening environment if you're trying to please multiple people: stuff gets in the way. Give your rear passengers a chance to experience the music in a relatively decent fashion: add some rear fill. Even if this is a considerably diminished presence in the rear, it does give something to the passenger. Heck, maybe you've been to a concert where you heard sound reverberate off the back wall and you're wanting to duplicate that.

Lastly, rear fill can be an easy way to make some improvement with very little effort. There's no need to EQ, Time Align, or change positioning of your drivers if adding a couple speakers in the rear deck brings a little more height to you. Sure, this isn't a great solution, but it's easy and that's good enough for you. Or maybe you are one of those weird bass heads who packs 8 18" high excursion drivers on 10 kW in your vehicle: adding a couple of speakers may help add some SPL to your frequency response at certain frequencies.

In general, it is safe to say that "rear fill" is not an absolute or technically correct solution when aiming for the most accurate reproduction. At the same time, some people do, in fact, prefer it for a reason. I think it is well worth educating someone on why you may or may not disagree on the use of rear fill, but perhaps there is a more appreciated way in which you can convey your opinion without telling someone their desires are wrong or why their advice is unwarranted.

[dopey 0]

Ok, let's think about this for a few moments. First, let's try to avoid telling someone that they're not welcome in any threads. Take the advice given or discard it: it's your choice. At the same time, we want to try and keep things friendly here, so if you have an issue with any member, it's probably better to hash that out in pm's, mmmkay?

Now on to the fun part...

First, let's define what we mean by "rear fill". In a traditional sense, this would be a set of speakers in the rear of the vehicle that cover all frequencies already predominantly handled by your front stage. A more current definition seems to be any set of speakers in the rear of the vehicle, whether this be handled by a highpass, lowpass, bandpass, or allpass filter. It's safe to say that everyone who has posted in the thread is relatively familiar with both sides of the coin, but I'll mention it for a moment anyways.

I'll be very clear in saying that I never, ever, ever use rear fill. As an engineering student, everything I do is based on the laws of physics. The concept, if you're not familiar with it, is that of constructive and destructive interference. Constructive interference occurs when two interacting waves at a given frequency result in an increased amplitude at any point in the period we are analyzing. Destructive interference is just the opposite: the interaction of the two (or more; this can be an infinite number) of waves results in a decreased amplitude. These increases and decreases is a result of the phase of each wave. If the coinciding waves are in phase, we will experience an increase in amplitude. If the coinciding waves are out of phase, we will experience a decrease in amplitude. Perhaps a visual will help here. The example on the left shows two waves, in phase on the bottom, and their summation above. The example on the left shows two waves, out of phase on the bottom, and their summation above.

So how is this relevant in a vehicle? Quite simple. Assume speaker A and speaker B are wired identically. From a relative phase standpoint, they are in phase. That's great. But what if these speakers are placed in areas that make them not equidistant to each other? Let's assume for a moment that speaker A is 2.5 feet away from your ear and speaker B is 3 feet away from your ear. Let's assume each speaker plays a 1000 Hz sinusoidal wave. To complete one period (or one full wavelength), the sound pressure from each speaker must travel approximately 1.2 feet. Speaker A will complete approximately 2 full periods (2.5/1.2=2.08). Speaker B will complete approximately 2.5 periods (3/1.2=2.5). At this point, the speakers are in fact, out of phase, in an absolute sense. Here, we're experiencing destructive interference. Simply put, we're seeing nulls in our frequency response that shouldn't be there. This just isn't a good thing.

But it's much worse than that! Sound is directional and gives directional cues. A speaker in the rear sounds like a speaker in the rear, believe it or not. It will undoubtedly pull your sound stage rearward, which is never a good thing from a matter of accurately reproducing music. But...

There are in fact logical and understandable reasons for using "rear fill", no matter what our definition of this is. When was the last time you could easily fit a large format midbass driver with considerable output in your kickpanels or doors? A little discussed fact is that high midbass output down to 40-50 Hz is one of the big differences between award winning sq vehicles and "also-rans". In fact, you'll find this fact to be demonstrated frequently throughout car audio history. Richard Clark's Buick Grand National had midbass in the rear. Harry Kimura's best sounding vehicles have had rear midbass; in fact, almost all of the best sounding Speaker Works vehicles have had midbass in the rear. There is in fact, empirical evidence that midbass in the rear works because the directional sacrifices that are made are overcome by the presence and output of the midbass. This is just one legitimate reason.

Second, any rear passengers in a car will have a very hard time experiencing the front sound stage that you worked so hard to perfect. The vehicle is a horrible listening environment if you're trying to please multiple people: stuff gets in the way. Give your rear passengers a chance to experience the music in a relatively decent fashion: add some rear fill. Even if this is a considerably diminished presence in the rear, it does give something to the passenger. Heck, maybe you've been to a concert where you heard sound reverberate off the back wall and you're wanting to duplicate that.

Lastly, rear fill can be an easy way to make some improvement with very little effort. There's no need to EQ, Time Align, or change positioning of your drivers if adding a couple speakers in the rear deck brings a little more height to you. Sure, this isn't a great solution, but it's easy and that's good enough for you. Or maybe you are one of those weird bass heads who packs 8 18" high excursion drivers on 10 kW in your vehicle: adding a couple of speakers may help add some SPL to your frequency response at certain frequencies.

In general, it is safe to say that "rear fill" is not an absolute or technically correct solution when aiming for the most accurate reproduction. At the same time, some people do, in fact, prefer it for a reason. I think it is well worth educating someone on why you may or may not disagree on the use of rear fill, but perhaps there is a more appreciated way in which you can convey your opinion without telling someone their desires are wrong or why their advice is unwarranted.

That was one of the best posts I have ever read. Thank you VERY MUCH for taking the time to post that.

This is the reason I want a HU with time correction (phase adjustability). I'm not too aweful concerned with PERFECT sq, just lsq. actually Lsq.

And btw, this jizzlobber has followed me around, posting chit in my threads, getting off topic, making fun of me, my system, and all kinds of chit. I don't know if he's jealous or what...but he's acting like a total jack ass. I have NEVER posted crap in his threads, and I generally try to stay away from people with that bad vibe. But he won't stay away from me.

The mods have had to modify his posts on numerous occasions, because he has been such a complete waste of bandwidth. It should be cool now. He's on /ignore.

Again, devildriver thank you very much!