mriches

where do you get those CF speakers?

-ANNX-

They are Memphis Car Audio 15-msync8.

rocketgyrl

The midbass region is from ~80-250hz, midrange from ~250hz to 2KHz, and treble from ~2KHz+. These are NOT arbitrary numbers picked out of a hat. They're selected by the manner in which our ears are shaped, and thus capable of hearing different frequencies, and therefore how we can work with physics to create a musical system.

Generally the subwoofer's should only play from 80hz and down. Why? Because if they are allowed to play higher, our ears will easily localize them behind us. An 80hz sound wave is ~6" long - similar to the distance between our ears. Frequencies lower than this (and thus longer in length) become increasingly difficult to locate because we haven't heard the entire wave. In my car, I'm using a 31hz low pass for my subwoofers, and 40hz high pass on my midbass. The tC has a ton of cabin gain in this region, and thus "fills in" the gap naturally. I don't suggest anyone use these ultra low crossover points unless you've got some killer midbass drivers, and/or don't jam on the system. However, there's a HUGE difference between 40hz and 80hz. The speaker will move 4X as much for the same output at 40hz vs 80hz! You can see how quickly you'll run out of mechanical excursion. I suggest something in the middle for most listening - say ~60hz @ 24dB/oct. Do NOT mix and match crossover slopes! This will result in several phase issues. Generally speaking - in car audio, steeper slopes (24dB/oct) are better, and use the same frequencies on each side of the xover. For example: 80hz low pass for the sub, and 80hz highpass for the midbass.

Let's remember that IDEALLY we want our stereo's to reproduce music as if we were at the venue it was recorded at. Visualize an acoustic performance - say at a coffee shop where the band members are setup left to right against a wall, with the lead singer centered. Our table is 10 feet back, and left of center. Of course, NONE of the musicians or their instruments are behind us, making 100% of the musical energy coming from in front of us.

Our car's should be able to reproduce this exact sonic experience. One of the ways we can do this is to properly set the crossover points. The lower the crossover frequency we use for the midbass, the more musical energy will be coming from in front of us. Subwoofers should only add to the impact in the lowest octaves. I would suggest using a high crossover point from the midbass the tweeters...something ~2KHz+. This will force most of the critical midrange to come from ONE pair of speakers, and will help maintain sound stage focus and thus image placement and stability will be much better.

rocketgyrl

By the way, the 8"s in the doors is SWEEEEET! GREAT JOB!

Keeshwah

Good info, I was wondering when you were gonna tie it back to the thread though.

-ANNX-

How do I do that?

rocketgyrl

Do what? Set your crossover points? What's the rest of your system consist of (CD player/amps/etc.)?

-ANNX-

I'm sorry, I was asking how to tie back info to the thread? But, what you said is enlighting and I think I love you for talking so dirty.LOL.

-ANNX-

Actually I do have a Question for you. Do I set my 8" components to 80hz highpass? What about my 5 1/4 components that I have in the rear location, set them to 250hz highpass?

My system consist of :
Pioneer D-3
Memphis M/class 50x4 @ 4ohms
Memphis M/class 500d @ 2ohms
Memphis 8" components
Memphis 5 1/4 components
Pioneer Shallow Mount 10" sub

Adidude

I know. The last time I did this in my last car it was not optimal, I ran the 8" underlapped from 63-250Hz and the mid from 315-4K and the tweeter up from there. In this install I am using a different mid and tweet. I am still in the planning phase but I hope to run the midbass from ~63~150 and the mid from 150-4K and the tweeter up from there. I am still in the planning phase and may have to make some changes since the tweeter I wanted will not be available until August. So far I have the midbass, a prototype DLS 8", the mid 1 4" Scan Speak Revelator home speaker and the sub which is an Image Dynamics IDQ15. Still trying to decide on the tweeter at this point.

rocketgyrl

Yes. That's a good starting point, though the 8"s could handle a bit lower - even at higher output levels...I'd try something like 60hz.

The rear speakers will just have to try and keep up with the 8"s. I'd try something like 80-100hz, and reduce the output to the point where you can't directly hear them, but if you keep reducing the output, it starts to sound like some thing's missing...

BTW Adidude - Sounds like you've got the makings of a very nice system! The Scanspeak 2904/6000 tweeter is a great match for those 4"s...

Adidude

Do you happen to know if the Scan D2904/9400SE is the same tweeter but just in a large format? If so I may just pick up a set on sale from Madisound and save $60

Tcguy85

[quote="rocketgyrl"][quote="1nicescion"]i don't agree, if you set both of the crossovers at the same point you will get a lot of overlapping. i have my sub crossed at 63hz at a 12db slope and the interiors at 80hz at a 12db slope and it sounds much more natural than if i crossed them both over at 63 or at 80. i do agree with you saying to always use the same slope.

anyway... great job on putting an 8" in the doors. where is the mid and tweeter located? any pics of those?

rocketgyrl

By setting one at 63, and the other at 80hz, you've created a "notch filter" (similar to an EQ)...nothing wrong with that, as long as it sounds better! It's likely the vehicle needed reduced output in that region..most cars do.

Anyway, the Linkwitz-Riley filter alignment provides -3dB at the xover frequency from BOTH drivers, and when summed = 0dB. Please see:
http://en.wikipedia.org/wiki/Linkwitz-Riley_filter

The ScanSpeak tweeter is similar, but not identical. I'm sure either one would be an excellent choice, but since the 2904/6000 is much smaller, it would be my #1.

nodsetse

Using the same filter frequency for both drivers is just a general rule because that's what has been common for years, and works well for many people. There are many exceptions and variations that also work, because what's best is subjective to a great extent.

The optimal attenuation rate ("slope" or "rolloff") varies depending on many factors, and that's the main issue I have with what you implied. Most people who have been heavily into audio for a long time tend to agree that steeper slopes are better, and 4th order L-R is superior to 2nd order Butterworth in many ways. This really only pertains to active filtering, as there are additional factors when considering rates for passive crossovers. Sometimes it can even be best to use 1st order filters to cross over between drivers, such as when a mid and tweeter are separated by a great distance.

Glad you found what works best for you in your install, but also hope you'll be open-minded about trying steeper rates (and even the same XO point between drivers) in the future, as they might benefit a different system or set of ears.


I think you meant to say L-R is -6dB at the XO freq and sums flat, not -3dB like the more common Butterworth alignment has. Of course I'm sure you're already aware of the other advantage L-R has over most others, which is the output phase. Once people use 4th order L-R active filtering, it's often difficult to be satisfied with anything less.

Tcguy85

i would have done an 18db slope but my deck only allows for a 12db slope for the interiors but an 18db slope for the sub but i know it's best to not mix slopes.

and i'm pretty open minded and have tried numerous settings and tweaks. my passion is cars, especially car audio.

rocketgyrl

L-R = -6dB My bad.

I forgot to mention that my system has mismatched crossover frequencies. I'm using 31hz (LP) for the subs, and 40hz (HP) for the midbass - to 3.15KHz, then 3.15KHz+ for the tweeters - all at 12dB/oct (my H/U won't do 18 or 24). I've found that the tC "booms" in that region (30-50hz, like most cars), and in order to get the bass to sound right, removed those frequencies out electrically, and allowed the tC to acoustically fill them back in.

Tcguy85

nice.

nodsetse

You said that a couple times, but didn't state why you feel that way. I'm curious what your rationale is, so it'd be great if you could provide a technical explanation, such that others might understand your perspective.

I really like your choice on the 4" drivers, and that you're going the DIY route. As you're familiar with Madisound (save the money and use those tweeters, imo), I'd guess you also know about Parts Express, since they have a good selection of drivers too. If you don't know, another place you might want to check is MCM, as they have quite a few too, and ApexJr is another site that might have some interest to you.

nodsetse

Underlapping like that is fine, and could improve the fidelity of many systems if more people understood it. One reason it works in a lot of systems isn't just due to the vehicle's transfer function helping to fill in the gap, but because most people have their sub amp's gain set such that the amplitude difference (relative to the MB/MR) really makes up for a lot of the frequency underlap. That's one reason why a lot of people have systems that produce too much midbass boom, when they don't underlap, and have the sub SPL at a much higher level than the mids.

I understand what you did, why you did it, and believe it works very well for your system. However, I am a bit uncertain about your sub's filter, did you really mean "31Hz LP", such that they're only getting the signal below 31Hz? I'd have thought they were getting at least up to 50Hz, considering the dB you're able to reach when competing. I've actually done kind of the opposite for many years, as I really like the advantages that subsonic filters provide, and mine is 6th order with a -3dB point at 27Hz.

Aren't you running a 3-way system, with the subs and the Seas components? If so, I'm really surprised that the mids can handle 40Hz to >3k, while still playing cleanly at loud volume. Getting a greater than 6 octave range while maintaining good performance throughout that entire passband is a lot to expect from any dynamic transducer, but based on your apparent success, that must be one heck of a speaker.