Impious

That is quite possibly part of your problem. Most car audio mids are designed to be used infinite baffle in a door, putting them in a small sealed enclosure is going to potentially suffocate them and kill the midbass response. You need to determine how much airspace you have in there. What I've done in the past is create an opening in the rear of the kickpanel that mates to an opening in my kickpanel area that vented to the fender well....making my kickpanel an infinite baffle. Second option is to try cutting a hole in the back of the kickpanel and vent it into the carpet. This of course assumes you have some fiberglass skills to potentially fix anything that causes a negative instead of positive change. You can see what I'm talking about in my build log for my old kicks:

Midbass has a lot to do with installation. I assume this is a door installation. Have you deadened & sealed your doors? If not, that's step one. No sense in changing speakers until you have the installation solidified.

It is. It's called "salesmanship"

I presume a passive crossover? Terrible idea. Without knowing the crossover frequency, you are just throwing darts at the board. If you don't use drivers of the same impedance as the crossover was designed to be used with, you will change the crossover frequency and end up with giant gaps in the frequency response. If the passive has any built-in extras, such a zobel networks, they will be rendered useless and change the behavior of the crossover. Generally speaking it's less than ideal to use a passive crossover with any speakers other than those with which it was designed to be used. I think you need to take a step back and come up with a better plan for something within both your budgetary, equipment and knowledge constraints. No offense, but based on your posts in this thread I don't think an active setup would be a great plan for you right now at this moment in time. I think your best plan of attack would be to find a good pre-designed component set. What are your speakers right now?

I don't care what the website says. Don't use that driver up to 5khz.

I'm not sure I understand. You were going to run both 8" mids together in parallel bridged from the amp? DO NOT do that. What were you planning to use for a crossover?

LOL....they aren't useable up to 5khz, atleast not by my definition of "useable". Depending on your definition of "useable" you could claim an 18" subwoofer is "useable" to 20khz. How are the mid and tweeter going to see 250w ?? That amp is rated 80w x 4 @ 4ohm

Didn't answer all of the questions. Need to know the model of the midbass, what your goals for the system are, what equipment you will be using, what your preferences are if you know them, etc etc.

Would need significantly more details about the system, goals, etc. Most importantly the model # of the mids, Selenium made more than one 8" mid.

Personally I would probably just wire one amp per coil. Saves the issues of figuring out how to strap, a simple DMM can be used to match the amplifiers, and there's no loss in performance.

You are not going to want to mate an 8" driver to a supertweeter. Really most 6.5" driver's won't really work well either. Supertweeters don't play low enough, any driver of reasonable diameter isn't going to play high enough unless you plan to aim them all on-axis and even then that only partially solves one of many issues. Best solution is to ditch the supertweeter and use something more logical.

Country and rap are the same thing. Both talk about nothing but women, drinking and their vehicles.

I was literally reading this sentence when my son walks in and asks if he can eat some pickles. Gnarly.

I was unaware it was a consistent problem. My bad.

Let's keep the classifieds in the classifieds and not in OT.

Just as an FYI, this is a message Don just posted on another forum a few hours ago. I hope he doesn't mind I'm posting it here, but it explains why it can sometimes take him some time to respond to a message:

What are the details of the enclosure they are in now, and how much room do you have in the vehicle that you are willing to dedicate to the enclosure?

Took you up on your sarcastic suggestion and performed some "real world tests". Measurement system consisted of my laptop connected to an M-audio Mobile Pre using a Dayton EMM-6 mic. This was connected to my HT receiver driving a Coustic 306P 7" mid. So this includes the entire signal chain, from source to amplifier to speaker reproduction. I used HOLMImpulse to perform the measurements. The short cables consisted of a 3' Dayton RCA cable and 3.5' length of Stinger 14ga speaker wire. The long cables consisted of a 17' Stinger RCA cable and 10.5' length of Stinger 14ga speaker wire. The first (red) measurement was with the short RCA cable & short speaker wire. The second (blue) measurement was with the long RCA cable and short speaker wire. The third (green) measurement was with the long RCA cable and long speaker wire. As you can see from the graph, the measurements at the initial impulse for all three measurements pretty well overlay each other. Within the resolution of the measurement (tenths of a millisecond), they are for all intents and purposes identical. If there were going to be significant differences due to cable length, it would be revealed here in the impulse measurement as the "slow" signal cable transfer would have an initial impulse later in time. The results indicate rather definitively that there is not going to be any real world difference in the performance of the system due to any realistic differences in speaker wire (7' difference) or RCA cable (14' difference) lengths within a typical car audio system. In summary.....the physics dictates that the differences are beyond the realm of audibility and well below a level that would affect system performance in the slightest. Real world testing confirms this to be true as there was no realistic difference in impulse response time between cables with relatively large (relative to typical audio cables) length differences. So, we are left to revert back to my original analysis. You are simply attributing the issues you experienced in various systems to the wrong variable. The variable you are attempting to claim was the cause of the issue, delayed signal transmission due to varying lengths of cables, can simply not be the cause......either directly or indirectly. If you have an explanation as to how any of the systems you described were able to defy the laws of physics, I'd be more than interested in hearing about it. Otherwise, we'll agree they obey the laws of physics and you're understanding of the cause of the the issues within the systems was simply incorrect. *For reference, the impulse is negative because the mic was located on the rear side of the speaker when I measured. Also, an absolute time measurement isn't important here, we simply needed to determine what the relative differences in impulse time between measurements were. As long as the results are consistent, the absolute value isn't of consequence. So the absolute value of the impulse isn't properly aligned as I simply didn't take the time to mess with it as the results were consistent. I took multiple measurements with each cable to verify the results were consistent with each cable. Damn, the picture is smaller than I had hoped I think it still conveys the information though.

I haven't overlooked anything you have said. You are overlooking the fact you are ascribing the issues you had to the wrong variable. It wasn't due to differences in arrival time of the signal due to differences in cable length, either directly or indirectly. You have yet to give any explanation consistent with the laws of physics that would allow what you have stated to be true, other than "I've seen it, so just believe me." You've stated scenarios in which you think it was the cause of the issue, and again I will tell you that you are ascribing any differences to the wrong variable. No matter what cable was used, no matter what amplifier was used, no matter if they were common chamber or separate chambers.....the signal transfer is going to be such a significant percentage of the speed of light that it is not the issue. If I get time later and if I can get my measurement setup to work properly, I will measure the difference in impulse response between different cable lengths and post the results. If what you are claiming is true, then it will be readily apparent in the impulse response measurements.

For the love of god I wish people would quit using that term just because they have found something else they like that is less expensive.

The science books say it's impossible or improbable.....because it's impossible or improbable. There is nothing that changes in this particular scenario between the science theory and reality that would make the latter different than the former. The signal transmission is simply too fast to make any noticeable difference at the distances we are discussing. If you think the Bronco somehow defied the laws of physics, I'm sorry to disappoint you....but it did not. If what you are claiming is true, there are a hundred different scenarios in audio applications where this would rear it's ugly head. Helotaxi listed one such aspect above. Another issue would be with amplifier RCA pass-through outputs....you wouldn't be able to use them due to the time delay involved. Overall this issue of time delay would be a significant factor in every system design. The fact is that it isn't. And the reason it isn't is because of the physics involved, and these physics are the same between the science books and the "real world". It's simply too quick of a signal transfer to make any noticeable difference. I'm sure there were some bugs in the system in the Bronco. And I'm sure you made some changes that corrected them. I'm not disagreeing with that aspect of your experience. What I am saying, however, is that you are ascribing the differences that existed to the wrong variable. It wasn't due to a time delay resulting from a difference in RCA/speaker wire. It's simply not possible according to the laws of physics.

Impedance changes based on frequency, enclosure, temperature of the voice coil, etc etc. But the goal of the DMM method isn't to set the gain based on the impedance of your subwoofer. What you are attempting to accomplish with the DMM method is setting the gain based on the output voltage of the amplifier at a known power output at a known impedance, namely the impedance the amplifier's output power was rated at. If the amplifier is rated 100 @ 4ohm and you are attempting to set the gain....in theory it doesn't matter if your subwoofer is 4ohm, 3ohm, 2ohm, 1.3ohm, 3.6ohm, etc. What you need to know is what rail voltage the amplifier should be operating at, and adjusting the gain control of the amplifier to achieve that rail voltage. Ideally the output voltage of the amplifier would actually be independent of impedance. If the amplifier is rated at 100w @ 4ohm, that means the amplifier is capable of operating with a 20v rail voltage. In a perfect world, this voltage (20V) would remain the same no matter what impedance load was connected to the other side. The actual power output would depend on the load, as that determines the current output and ultimately the power output, but the rail voltage itself wouldn't change. So, in a perfect world, all we need to know is where the output voltage of the amplifier should be, and we determine this based on the rated power (which is a specific power output into a specific impedance load) and not what the impedance of the load is that is actually being connected. In practice it does matter as there are some design features and losses that occur within an amplifier that affect it's ability to maintain that rail voltage at higher power/higher current output situations. In many amplifiers the output voltage will decrease as impedance decreases, which decreases it's power output (normally due to current output constraints, power supply constraints, etc etc). But, again, we can use the rated power to approximate where the rail voltage should be for the approximate nominal impedance of the load we are connecting. It won't be perfect, but it doesn't need to be as small differences won't be noticeable in either direction. Another issue is where rated power falls in relation to actual power output. The amp might be capable of more or less power than it's actually rated for into the specific impedance it was rated at. In all but the most extreme circumstances they will be different but not by an excessively large amount. That means the voltage setting could be a little high or a little low....but again, small differences won't matter. The larger issue for me is the level of the test tone. If you use a 0db test tone (which most people use/recommend), 90% of people will end up unhappy with the result and think the need to buy a more powerful amplifier. Since music hardly spends any time at 0db, you will have a very low average power output from the amplifier. With a -6db or -10db test tone (depending on circumstances), the DMM method is good enough to get the gain set to a level that is relatively safe and leave most people happy. The problem is, you could probably do just as well by setting it by ear....so why bother? There are other issues as well that overall just make setting the gain by ear the easiest and best solution a majority of the time.

For some "real world tests", let's consider the speed of signal transfer. The speed of electric signal transmission depends on construction and materials of the copper wire, with co-axial cable being on the low end at ~66% the speed of light. I'm going to round this to 70% because I was able to find a wikipedia page that already has already used that number, so it saves me the time of having to manually calculate anything. With a signal transfer of 70% the speed of light, it would take a signal 4.76 nanoseconds to travel 1m. That's 0.00000000476 seconds to travel ~3 feet. I'll leave it to the reader to calculate the associated phase shift resulting from a 0.00000000476 second signal delay. And for reference, that's also many orders of magnitude below the audibility of human hearing for signal delay. I'll defer to your experience with "real world tests" and await an explanation as to how a 0.00000000476 second delay resulting from extra RCA cable length or speaker cable length is going to cause an audible delay or audible phase shift within the system.

Unless he is wrapping the speaker wire around his car a few times first, which I doubt, then I seriously doubt a foot or two difference of speaker/RCA cable is going to make any audible difference at all. I would question your test methods.