Re: Assistance Choosing 3-Way Component set
If you want it to sound its best, you DO NOT want multiple drivers on each side playing the same freqs. Midbasses facing each other has zero, zip, nada, niete, to do with cancellation. The pathlength from the speaker to your ear does. Unless you have the pathlengths perfectly equal physically or you use time correction for EVERY driver, you will end up with a peaky response. Also, cancellation does not occur at every frequency. Depending on pathlength and wavelength, some frequencies will have perfect cancellation and others will have perfect reinforcement. As you add more drivers at a given frequency, you create more different pathlengths that you have to deal with. This creates even more peaks and valleys in the response curve and the overall result is your speakers sound much worse than they potentially could. These phasing peaks and more importantly valleys, cannot be fixed with EQ either. If you create a cancellation valley in the response curve, you are pretty well stuck with it. As I hope you can tell by what I have said so far, the install is more important than the number of drivers when it comes to good frequency response.
If you want good midbass response there are a few key things that you must address. first you need a true midbass driver, not just a large midrange. Just because it is 6.5" doesn't mean that it has good low end extension. You want good usable output down to at least 80hz and lower is better. You don't really care about the response above 300-500 hz, you will let the midrange pick it up somewhere around there (exact frequency will depend on the install and the particular drivers). It should have pretty good excursion or be a larger driver like an 8" (it needs to move a good amount of air to produce enough volume to blend in well with the subs). Once you have found the driver that is going to do what you need, you need to figure out the best way to install it. Location is one part of the equation, but probably the more important for a midbass is the enclosure that you put it in. Just like your subs, your midbass drivers need to be properly enclosed for them to perform their best. You should design and build an enclosure for them based on their Theile/Small parameters and you can go either ported or sealed, just like with subs. If you are running large subs or they are ported and pretty loud, consider porting your midbasses as well to give them the extra output they need to keep up with the subs. Once you have figured out how and where to mount them you need to power them. If you are going with a JL amped system, the 450/4 will give you what you need, as you have already figured out. 150 per side should be plenty for most any setup. Tuning the setup is the last and most often overlooked step in getting the sound you want. The biggest concern with dividing the frequency range among multiple drivers per side is getting them to blend with each other to produce a smooth frequency response. This task is made a bit easier with the use of active crossovers with infinitely variable cutoff frequencies and multiple channels of amplification. The first step is to set the crossovers in the ballpark of where they will be in the end. You can guess a bit here. Set the low pass for the midbass and the highpass for the midrange at the same frequency to begin with, although they might be at slightly different frequencies when you are finished tuning. Next set the gains on the different amps to match the levels. Set the gains of each pair of channels normally first and then turn down the pair (midbass or mid/high) that are louder. An RTA can help with this step by showing you which is really louder. Next you want to adjust the crossover points for the smoothest response. By playing with the overlap or gap between the low- and high-pass sides of the crossover, you can do a lot to fill valleys in the response or tame peaks. Try adjusting the relative phase of the individual drivers as well, as this can make a big difference. Remember that just because the wire is labeled + doesn't mean that it will sound best connected to the + terminal on the speaker. We are dealing with AC, current flows both ways, there is no + or -. They switch every cycle. The labeling is just a reference, not a hard and fast rule. If you have done things right up to here, your system should sound excellent. You should have been able to address the worst of the irregularities in the response curve using just location, phase and crossover points. That is what makes a good install. You have given yourself a solid foundation for excellent sound quality. Small bumps and dips in the response can be smoothed from here with a little bit of EQ if you so desire, but for daily listening, it likely won't be required.
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