Impious

The one I linked to was for flat response. There are several others on that website.

He said he doesn't plan on going active.

Is it possible to have a 2-way frontstage with an 8" mid and a tweeter? Yes, it is. There are some things that need taken into consideration, so these aren't "easy" setups to accomplish. But it's possible. Are you going to do it with an 8" subwoofer like the REx? No, you are not. Just because it's an 8" driver, it does not mean it will make a good mibass or midrange (since the driver would be playing well into the midrange). Drop the idea of trying to use the REx as a mid in a 2-way setup and just go with a pre-built comp set. Those Type-R components are actually fairly interesting; the mid uses a dual-gap motor similar to XBL.

As mentioned above, try reversing the polarity of one of the mids and see if that has any change.

Depending on his vehicle and the wire gauge he is using, the chassis may be a better conductor.

o.p. or OP stands for "original poster", i.e. the person who started the thread. I'm with Duran as far as audibility goes. That is assuming we are talking about changing frequency only and not enclosure size/etc aswell.

While I didn't completely understand your post......if you were planning to try to run the 8" REx with tweeters as your front speakers....No, not going to happen. Why not just go with the XXX comps if you were wanting to stick w/ RE?

I wouldn't go for the Daber given your intended application. Just going by inductance, the driver will have a self-induced roll-off beginning around 280hz, which is more than a half-octave below your desired bandwidth. I'm really not sure where this Qts of .35 thing came from? Qts alone isn't going to help you entirely. There is a significant difference in response between a driver with a Qts of .35 and an Fs of 70hz, and a Qts of .35 and an Fs of 35hz. The 2nd driver would have an F3 approximately one octave lower than the 1st in the same alignment. So you need to consider both the Qts and Fs to really determine the response. Really, what you're actually looking at is Qtc and Fc....in an ideal "IB" environment, Qts = Qtc and Fs = Fc. However, your door may not end up being a true IB environment. So the Qts and Fs may be different than the Qtc and Fc. You need to consider how your door is going to affect the driver, and the effect will be slightly different for every driver depending on it's Vas. The 2nd thing to consider is differences in driver behavior with different Qtc's. A lower Q is going to be more overdamped with a shallower roll-off and generally the least output above F3. Subjectively this is typically said to be a little "dry" or "sterile". A higher Q is going to be a little more underdamped with a steeper rolloff but slightly more output above F3. Subjectively this would be a little "thicker". A Qtc of .5 has optimal transient response at the cost of peak output and a higher F3. A Q of .707 has optimally flat frequency response, the lowest F3 and transient response that is still considered good. A lower Qtc typically has slightly more output at the lower frequencies (somewhere below F3) due to it's shallower rolloff even though the F3 may be slightly higher. F3 is the frequency at which the response has rolled off to a level of -3db. So, the main point of those brief paragraphs was to explain that your target Qts may or may not be ideal depending upon where you want your final Qtc to end up, and also that you can't look at Q alone you also need to consider Fs/Fc. If you were pushing the power limits to get the output you wanted in the midbass, a higher Q alignment may give you a little more output in the 60-100hz (depending on the Fc). Another thing to look at is inductance, or Le. A driver's inductance and resistance create a classic 1st order (6db/oct) lowpass crossover. You can determine the corner frequency with the formula; Frequency = Re/(2*Pi*Le) *Le in henries Ideally you would want this to be one octave above your intended crossover frequency. Additionally the response should be relatively flat within this bandwidth. If you can find some distortion and other measurements to make sure it doesn't experience any cone breakup or distortion issues within your intended bandwidth, that would be a bonus. I would also take displacement into account. The more the merrier. For example, with the Sd of that Aura, it will take 9mm of excursion to reach 100db. If you plan on listening at or above levels of 100db, you will need a driver with atleast 9mm one-way Xmax (with 346cm^2 of Sd). The louder you want to go, the more excursion you will need. Sensitivity.....meh. The only reason I ever really care about sensitivity is in regards to Hoffman's Iron Law. That's what I can think of off hand.

Put a wire everywhere you see a black line in the picture

It's been out all of a few weeks, there aren't a whole lot of of people who've heard them. From the reviews I've read, it performs as advertised when the proper methods are used when taking the auto-measurements. By all appearances, it seems to be more advanced than the Imprint system Alpine uses, it has 8-channels of routable outputs compared to Imprint's 6 channels, and to my understanding it's user adjustable after the auto-measurements are taken which Imprint isn't. All-in-all, it seems to be the best auto-tune system on the market and given it's advanced algorithms and internal tuning capabilities, it should be capable of achieving better performance with a couple minutes of measurements than an individual could get themselves given several days or weeks (or months) of tuning time with standard measurement equipment. It simply has more access to more features with the auto-tuning than most processors allow a user to adjust. From what I've heard, it can be finicky if the proper steps aren't taken prior to taking the measurements. For example, the speakers need to be relatively level-matched and the system can not be too loud or it'll throw off the measurements, turning your head too far or not far enough will throw off the measurements. So it's not completely idiot-proof. I've been debating whether or not I want to ditch my H701 in favor of the MS-8. From the initial reports, the tuning is very good and it's incredibly quick and easy. To me, the time savings and end results may be worth the premium. To others, it may not be. Or someone may be happy enough with their current system that the added cost isn't worth it. However, to get comparable results for less money expect to at minimum need a decent audio processor (H701, Audison Bit1, etc), access to measurement equipment and a whole lot of time.....it's not something you will accomplish on your own in a weekend tuning the system yourself. But usually, there are minor bugs that get worked out or minor improvements made after the initial release; so I may wait a year, let the street price come down some (or find a used one) and see if any changes get made before I spring for one. There are several hundred pages of info on DIYMA as well as several reviews.

Yes, if you set the switch to "full" then the filter is not effective. This is bad. You want to highpass your speakers.

Indeed, sounds like you need to decrease the frequency for the highpass crossover.

I reversed the polarity on one side of the components at the amp ( with the subs off) there was minimal difference, to me at least. When i open a door and stand outside of the truck there is no real midbass sound. You can hear the bassline in the music of course, but it sounds like a 6x9 with "bass blockers" on it. The supplied crossover doesnt have any adjustments on the mid side. According to the spec sheet the frequency response for the mid is "55Hz - 22kHz". There is nothing that ive found showing what the frequency of the crossover is. I have the filter on the 4channel amp set to "All Pass", and the Deck EQ Bass level maxed at 6 (mids at 5, Hi's at 6.) It won't tell you what the frequency of the highpass crossover for the midwoofer is because it doesn't have one. You need to highpass the midwoofer either via the amplifier's crossover or the HU's crossover. Set the crossover on the amplifier to "highpass" instead of "allpass" and set the crossover frequency unless if you are using a highpass crossover in your headunit. The headunit might not have one, but if it does then you need to look and see what it is set to. What headunit do you have?

Not necessarily. Anyways..."optimal" is a matter of opinion. There are advantages, disadvantages and trade-offs involved with all of the various alignments and a single formula is not going to be comprehensive enough to encompass all of these various factors. What's optimal for one driver or one goal may not be optimal for a different driver or a different goal. This is one of the main reasons you hear things like "you can't model a Fi BTL". You can, the physics are the same. The problem is that when you run the driver's parameters through the formulas for "optimal" enclosures meeting certain target curves such as flat frequency response, the results are nonsensical simply because the driver's parameters don't allow it to meet those target curves. Or if the formula you are using is the formula for optimally flat frequency response, you may be trading off low end extension or end up with too much low end extension for the environment, in which case that "optimally flat frequency response" won't be optimally flat in the actual environment. If you really want to know formulas, DIY Subwoofers has a lot of various formulas to sift through. Being a big proponent of empirical analysis, I find formulas extremely useful. However, when dealing with things like ported enclosures it's best to not focus or limit yourself by the formulas themselves but instead use an accurate analysis tool, such as an enclosure modeling program, to design boxes based on the given set of goals you are trying to achieve.

Good luck man. With any luck this will be an inspiration for me to finally get off my duff and actually start exercising for first time since high school.

And what would you reccomend in a $200 budget for both tweeters and midbasses It would be better to have this conversation in another thread of your own making

Alton brought up a good point with the phase. There are two different types of phase; Relative phase and absolute phase. The wiring of the speakers (having the positive wire from the amp connected to the positive terminal on the speaker) is relative phase. How the sound waves interact at the listening position (the "peak" of the soundwave from one speaker and the "peak" of the sound wave from the 2nd speaker both arriving at the listening position at the same time) is absolute phase. Relative phase isn't important. What we want is the speakers to be in absolute phase. Achieving this may require that we wire the speakers out of relative phase (reverse the polarity of one speaker relative to the other). Or, in other words, try reversing the speaker wires on one of the mids. Instead of connecting positive from the amp or crossover to positive on the speaker, try connecting the positive wire from the amp or crossover to the negative speaker terminal (and neg from the amp/crossover to pos on the speaker). This may help put the speakers in absolute phase in the midbass frequencies at the listening position, improving response. One word about phase, though. Since all wavelengths are different, some frequencies will be out of absolute phase while others will be in absolute phase. And reversing relative polarity will cause some frequencies to now be out of absolute phase while others will now be in absolute phase. This is one of the allures to using a 3-way front stage....you can wire the midranges out of relative phase without affecting the midbass (or vise versa). So, long story short.....just because all of the positives are wired to all of the positives doesn't mean everything is "in phase" when it reaches your head Unless I've still missed it.....where are your mids currently highpass? The crossover that comes with the speaker only handles lowpassing the mid, not highpassing it.

There is a specific type of filter that is called a "shelf", and it is different than a standard HPF or LPF. I would be seriously surprised if your HU included an actual shelf filter. In fact I'd be very interested in know what HU that was as I don't know of any, and very few car audio processors actually have shelving capabilities. The graph of a standard HPF or LPF look like a gently rolling hill; a shelf filter looks like, well, a shelf (hence the name). DEH-P7200HD also a shelf will have a slope just depends how it's programmed soft knee or hard knee octave (Q) and decibals are all contributing factors. LPF and HPF are shelving filters they are basically true curve EQ's that turn down to "infinity" Also if you have a right angle shelf or cutoff point it will sound unatural and unpleasent, slopes are a must with shelves Since I have a recording and mixing backgroud been doing it for 7 years narrow definitions are a must This is where my understanding comes from. There are highpass shelving filters and lowpass shelving filters, but they are not the same as a "standard" highpass and lowpass filter. Your HU has highpass and lowpass filters, not shelving filters. The two should not be confused. Example of a Lowpass filter; Example of a Lowpass shelving filter;

The Subwoofer DIY Page - 4th Order Bandpass Systems: Box Calculations

Well, this thread got a bit sidetracked. Back tracking to your original question; I would first try solidifying the installation of your current mids before adding any additional speakers. You will want to seal any holes in your inner door to properly isolate the front wave from the back wave of the mid. Sound dampening the door to reduce rattles and resonance can be helpful as well to enhancing performance in the midbass. I may have missed it, but where are your speakers currently highpassed?

Depends on who you talked to I wouldn't have many qualms with that range being loosely defined as "midbass". There isn't a universal chart that everyone in the audio industry uses to define those ranges. They are fairly arbitrary and specific to whatever source you are referencing. 120-150hz is by far the most narrow I've seen, and nobody else in this hobby is going to use such a narrow definition. So don't get confused when people on the forums or manufacturers use a completely different (and less stringent) definition for "midbass". There was actually another thread not long ago on this exact topic; What is considered Mid Bass? - SSA Car Audio Forum It depends on their reasons for saying that. There are some good reasons, and some not so good reasons. First and foremost, there is no set rules when it comes to setting crossovers in car audio. Well, I take that back....there is one rule. That rule; Set them to where ever sounds best. It's that simple. Really, that simple. No one on the internet can tell you where to set your crossovers points, there's far too many factors involved that can't be adequately analyzed over the internet. It's just not possible. There are a few caveats to this ofcourse. One would be the potential for physical damage to the driver due to overexcursion....this can be analyzed pretty well from modeling the drivers and noting their excursion over the bandwidth at a given power level. The other would be distortion. If a driver has been properly measured to exceed acceptable distortion performance, then crossing the driver so that it stays out of this range would be desirable. But pretty much, outside of that, it's whatever sounds best to you in your system. Crossover Slope Basics Read the link. If it's still unclear, feel free to ask and we can fill in the gaps.

There is a specific type of filter that is called a "shelf", and it is different than a standard HPF or LPF. I would be seriously surprised if your HU included an actual shelf filter. In fact I'd be very interested in know what HU that was as I don't know of any, and very few car audio processors actually have shelving capabilities. The graph of a standard HPF or LPF look like a gently rolling hill; a shelf filter looks like, well, a shelf (hence the name).

I can't say I've ever seen a broadly accepted definition for "midbass". Just a simple google search for the definition of midbass results in 3 different frequency ranges from 3 different sources. The definition of "midbass" is going to vary depending on the source. There's no authority, that I'm aware of, that can or has defined the "official" range of frequencies that encompasses "midbass". Everyone's opinion and definition will vary. And just an FYI to others, when most people on the forums are discussing "midbass", as well as most manufacturers in our hobby, they are not talking about such a narrowly defined range. Here are the google search results; Regardless, our identification of sound and localization cues has little to do with what frequency range we arbitrarily define as being "midbass", and everything to do with the wavelength of the frequencies in relation to the dimensions of our head and the physiology of human hearing. If the slope of the crossover is decently steep, a subwoofer with a crossover point of 250hz should be pretty well within the realm of what I described above. That said, I wouldn't recommend a 250hz crossover point for a subwoofer for a number of other reasons. Without hearing the system, there are a number of reasons why the subwoofer might be obviously identifiable as being "behind" you. First would be any rattles/buzzing/humming/etc that may be coming from panels behind the listener. Second would be any mechanical noises that subwoofer might be producing. Third would be tactile sensations....for example, feeling the vibration of the back of the seat. That's a quick but certainly not comprehensive list of a few reasons.

Long subject. Unimaginably long subject. I'll try to condense it down into a digestible version. We localize midbass in the lateral plane only (i.e. left to right). We don't localize it on a vertical plane (high and low), and we don't localize it "front to back". Midbass is localized by way of what's known as Interaural Time Difference (ITD). That is, the brain localizes midbass laterally due a difference in the time arrival of the sound wave between the left ear and right ear. ITD dominates our localization ques in the frequency bandwidth where the wavelengths of the soundwave are longer than the distance between our two ears. Generally the more ITD you can generate, the wider the potential imaging. From this very basic knowledge, a couple things can be extracted. First, any midbass location that results in identical ITD will be indistinguishable to the ear....above your head, below your head, in front of you, behind you, it doesn't matter......as long as the ITD stays the same, your ears and your brain won't know the difference. Second thing we should notice is that worst location for a midbass is at a location that results in an ITD of zero; that would be directly in front of you, direct behind you, or directly above you. Related to this, since "imaging" in the lateral plane is a function of ITD, the "best" midbass location is a location that results in maximum ITD (i.e. the wider you can get the speakers, the better). Now, a few caveats to this: First, hearing rattling/buzzing/etc as a result of the midbass speakers exciting panel resonances (door panels, etc) or other noises will ruin the illusion. Second, the speakers must be operated within the bandwidth where ITD is the mode of localization. If you operate the driver outside of this bandwidth (this includes driver distortion, etc), then other factors will begin to contribute to our localization of the sound. Proper time alignment of the midbass drivers will need to be maintained with the other drivers in the system as well as between the midbass drivers themselves. Lastly (I think lastly, I'm typing this up semi-quickly), this does not take into consideration the effects of other factors such as reflections or other anomalies. In the midbass region, the physical aiming of the driver doesn't matter. The wavelengths are very large in comparison to the diameter of the cone. What this means is that the frequency response on-axis and off-axis is going to be identical. You don't need to worry about trying to aim the drivers at the listener or anywhere in particular. There is going to be no difference in response between being directly on-axis and 60* off-axis, for example. Drivers operating within a bandwidth where the sound is non-directional (i.e. no difference between on-axis and off-axis sound) are said to be in their "piston range". So, what did we learn from this very brief primer to midbass? Yes, you can mount midbass drivers behind you....your brain doesn't know the difference. Mount the drivers as wide as possible to maximize ITD. Aiming the drivers doesn't matter.

I guess I don't see the point in adding another set of speakers to a system just to cover a single octave. Seems to me if we knew more about the system there may be better solutions. Anyways, if you are dead set on adding these 8" midbass, and they are going "in the rear", why not port them aswell?