The old BMW 3-way question

If you are just going to do a single passive on the mids/highs there are several useful javascript passive x-over designers floating around on the internet. It would just invove getting x-over parts of different values and experimenting with them in car.

I think the reason why many here love active is because you can buy a cheapie active 2-way off of ebay to split the signal to your amps and get equal to if not better sound than passive and much less hassle, and more adjustability. It would only add one small box to your setup in the trunk, and save you a great deal of time fiddling, and cost equal to or less than all of the parts you would need for the passives. Now if you are going for a very complex active system, eq, 3 or more band x-over, things can get pricey.

I am not super familiar with the 300/4 but you may be able to accomplish an active system with just it, no other crossovers necessary. The other cool thing about active is the speakers get to use a lot more of the power they are sent... I am running 37.5W to my seas mids and they go louder and cleaner than I care to try and still maintain my hearing...

That's exactly the trick. To run a 3 way component set in the front (with a sub on it's own separate channel) would require 6 independant channels and a relatively expensive active crossover network for what could otherwise be handled by a decent 2 channel amp. Power loss through a passive network shouldn't be an issue with a JL 300/2 (150x2) or 300/4 (75x4) on tap.

There might be some advantage to running the 300/4 with the midbasses on their own channels (for independant gain control) and the mid/tweet on another, but there will still need to be a passive network at about 4kHz between them. My though was that the midbass would be better with a little more power on tap from the two channel option.

Adding a larger power and ground distribution network along with an outboard processor increases the complexity and weight more than a passive network on a performance car that I will be trying to keep fairly light.

The real question is the feasibility of the 3 way front setup. Has anyone here actually used something like the 51AT's in a 3 way setup in their car? Does this combination "look good on paper" to the guys with more experience here?

Really, only the ultimate DIY tweaker will really realize any SQ benefit from going all active.
(and since that DIY tweaker understands the issues at play - those are the things driving his tweaks at the controls, after all - the same tweaker could alternatively design a passive crossover to do the same thing )

The question is: What are your standards? Your point of reference?

It's highly likely that if you purchase a good off-the-shelf component set, you'll be more than happy, and have sound exceeding that of any factory system - if you properly prep each location where the components are to be installed (and that might involve a bit of speaker aiming, as well).

Consider not just the pie-in-the-sky dreams of what you can tweak with an all-active setup, but also the limitations...
...realistically, there's only so far you can tweak your Xover point, given a mid/tweet combo. Too high, and the mid will degrade, not being able to really react that fast to produce those high notes. Too low, and the tweet will bottom out, not having the excursion capability to be able to produce those midrange notes.

And of course, there is significant additional expense here...
With a traditional passive Xover setup, you power the entire set with a 2-channel amp (or maybe even just your head unit).
With an all-active setup, you need one channel of amplification for every speaker being powered - the active Xover going before the amplifier, in the chain.
That means it's not just that you are wasting the passive Xovers that came with the set, or that you are purchasing a good quality active Xover to do the job that you want it to - but also that you need to purchase multiple amplifiers...

If budget is any concern, I'd rather see any enthusiast purchase a single, decently powerful, high quality amplifier, and use the passive crossovers that were designed for the component set (and that design - and even tweakability - is likely very good, given a good component set ), instead of spreading that budget thin, maybe buying multiple cheaper amplifiers, a so-so quality Xover, compromising on the cabling, etc.

You already know the arguments for going all-active, those benefits.

I'm middle-of-the-road on the issue.

I have a Civic - my summer "good car" (sponsored SQ vehicle, local shop and DLS) that is currently a work in progress, but is going to be all-active, using a cool processor that'll hit the market in 2006 CES... and believe me, I'm feeling the hurt in trying to fit all these amps in here... four of them just for the SQ portion of the system, and then two bass amps for a separate SPL system.

And then I have a Pathfinder - my foul weather/winter car. it has a homemade Xover that I built, allowing a single big Alpine 2-channel amp to power 11 speakers in the vehicle (two tweets, four mids, four midbass speakers, and a subwoofer).

Both are SQ vehicles... things like imaging and detail being a priority.
It's certainly not that "passive = bad".
But there does seem to be a bandwagon - they can often inflate reality a bit.

geolemon said:

The question is: What are your standards? Your point of reference?

Click to expand...

As mentioned before, point of refernce would be "good" aftermarket passive 2/3 way components such as Boston Pro, JL XR, MB Quart, etc... I understand the stock (even the HK) stereo is nowhere near the SQ level of what most people here consider acceptable.

You are pretty much right on my train of thought with not wanting to spread things too thin with multiple independant channels (and amps, read: weight and complexity) when I can get the job done with a smart passive X-O. Heck, I'll even look at adding a Zobel into the passive XO if that's what it really needs. To me, this is still easier and simpler than a network of signal processors and extra wiring in the trunk.

This car will be a driver, not a show only car, so the trunk needs to remain useful for luggage on trips without removing components. Speaker location is unfortunately pretty much set. I don't want custom door panels, so the stock locations will have to work. I'll do what I can (dampening, baffle reinforcement) to optimize these locations.

So any thoughts on the actual driver choice?

For front components, I'd personally look into a DLS component set - they have a very nice dome midrange that is possibly a decent fit into that location - I say that with the disclaimer that you might need to modify something in there to make it fit behind the door panel - it is a dome, not a cone driver.

But don't feel locked into a 3-way set, just because that's what the car came with...
There are ZERO that are drop-in-replacements for that particular setup, really.

There are TONS of two-way sets out there that cover the entire frequency range without compromise - especially since you mention that you don't have any extra-ordinary needs - and especially since you couldn't call BMW's choice of factory speaker locations really "ideal" by audiophile standards anyway.

By using the factory 5.25" kickpanel location with a 5.25" two way set, and either using the factory tweeter location, or possibly experimenting with a tweeter in your sail panel (behind the mirror), you can greatly improve what you have now, with just a single component set and a 2-channel amp to power it.

And of course, by adding a sub in the back and a single channel amp to power it (or a second 2-channel amp bridged, is often a great balance of power for a SQ system), you'll round out the bass end of the equation. Again, if you have no extraordinary needs, no need for anything outrageous - JL has nice stuff, and if anything, the sub and amp you mention are even overkill - very nice, perhaps a bit pricey, but outside of that difficult to criticize. I hate to mention or recommend specific products or brands, because individual products each have individual properties - it isn't as though one is better than another, most often. What really needs to be considered is the whole chain, the install, the personal past experiences and resulting expectations, etc - it's a system, truly - so that JL W6 for you might be great in one application, bad for you in another application, great for one person regardless of application (no kidding either ), and bad for yet another person in all cases no matter the enclosure, etc...
Hope that helps though.

WOW, dug up an old thread, eh? I guess it's update time...

After a ton of research in inquiries, I settled on committing to a 6.5" installed in the factory 5.25" location in the kickpanel (after a little sheetmetal work) behind the factory grille. This works great and I'm using a Peerless 4ohm driver. The front stage is run by a JL 300/4 for a cosmetic match to the existing 500/1.

The first attempt was with HLCDs. I used ID minihorn bodies with eminence 8ohm drivers. At this point, I chose an active X-O with 1200Hz on both high and low pass @ 24dB/oct. The horn bodies were mounted directly under the dash and as far toward the sides as possible. No real loss of foot room, even with the dead pedal and clutch in there. Sound quality an imaging were PHENOMENAL at one listening level (which was arguably fairly loud). Seriously, if you want to impress people with how loud your system is, this is the sure-fire ticket! I could hear everything even at 80mph with the windows down. Turning the volume down left a big hole where the efficiency of the HLCD and 6.5" cone diverged. There was really no way to sound good at both moderate and elevated levels with overall balance between the drivers. I tried multiple combinations of EQ settings and channel gains, no luck. Since I couldn't live at 100dB all the time, I needed a change...

Next up, active control with a silk dome tweet (Alpine DDDrive 6ohm) and the same midbass. I tried a bunch of different tweeter locations and found the kick panels best overall for imaging. The stock location in the door sucks, but pretty much anywhere on the kick panel is very forgiving. To this end, I found they still sounded great with the tweeter pushed further up and forward on the kick panel, which gave more foot room, reducing chances of a retarded passenger hitting them. This put the tweeter slightly off axis to the listener, but further away, reducing PLD's.

At this point, I was still active with X-O points sounding best around 2kHz/18dB low pass and 2.4kHz/24dB high pass. It sounded cleaner than the HLCDs at moderate listening levels, but still not completely natural with all types of music. Multiple EQ setting changes, and still no luck. I was always finding myself readjusting for each new CD I grabbed.

Last ditch effort, back to passives. For simplicity, I grabbed the Alpine passive network that originally came with the tweets. The DDDrive mids left a lot to be desired, but I always liked the top end, so why not use this with my new Peerless setup? I changed from 4 channel active to 2 channel passive 75wrms/ch into the passive network. Instantly things sounded more natural. After a little EQ work, I reduced the massive bump in cabin gain around 600-800Hz and pretty much nothing else needed adjustment. Almost any CD I grabbed now sounded like it should. The overall level was lower than with the active network, but a compromise I'm willing to make for not having to constantly readjust. Imaging is still strong with good center location and L/R separation. Sound stage is right about dash level. Not bad considering the actual speakers are all at toe height. I'll be keeping this setup.

For reference, the final combo ended up being:

Eclipse CD head unit with 24bit D/A and full EQ (I forget the damn #)
JL 300/4 and 500/1
Alpine Silk Dome Tweets on the top/forward portion of the kick panel
Peerless 6.5" 4ohm midbass in stock location enlarged to fit.
Alpine passive X-Os hidden beneath rear seat
JL 10W6v2 in custom 1 cu ft sealed fiberglass enclosure in trunk corner

Digging this old thread up for another go-round...

I decided to give the horns another shot with some proper adjustments. The fundamental problem I had with the HLCD's overpowering the rest of the stage was link to amp gains. I was running a 1:5 power ratio (~15wrms to the horns, 75wrms to the mids) , which just wasn't enough. The extremely high sensitivity of the HLCD (appx 111dB @ 1w/1m) means that as volume is turned down they just don't lose output the way the mids would. They are so efficient that they play "loud" with very little power.

The solution ended up being even less power to the HLCDs. I went down to a 1:10 ratio (~7.5wrms to the horns) and finally found it livable. The horns now blend seamlessly at all listening levels, with a single EQ setting. I'm happy with where it sits now and don't see how I'd go back to traditional 1" domes. All crossover duties are now done completely active in the two JL amps' settings.

I ended also improving the bass output by porting my existing sub enclosure. I was running a ~1cu ft sealed box with a 10w6v2 in the left rear corner of the trunk running off a 500/1. The BMW's unforgiving transfer function really worked against me here since the M3 doesn't have a ski-pass available to directly couple the sub to the cabin. Breaking out the box calculator and double-checking JL's site showed that a port tuned to ~39Hz should give me at least a 3dB boost across the board from 30-80Hz right where I needed it. I chose a 2.5"ID flared port tube from Parts Express and simply popped it in. Surprisingly, the math works. This change alone netted a dramatic improvement in in-cabin bass without any excessive port noise, noticable decrease in subjective SQ. The guys at the Michigan meet heard it a while ago and I don't think anyone was left asking "where's the bass?"

Overall, the system meets my "KISS" theory with a minimum of extra weight or complexity. It has enough bass to pressure load and images well enough to forget what kind of speakers are playing and where. Not bad for 5 drivers and an amatuer install. The car is for sale if anyone is seriously interested.

Bringing this one back up...sorry!

First of all, to eficalibrator...what do you mean by "Now sporting dueling LSx's for summer and winter..."? Sounds tasty!

Fellow (estoril) E36 M3 guy looking to change an aftermarket system. I've owned the car for three years now and the system has always bothered me. I'm a relaxed audiophile, I love great, accurate sound but don't need to go overboard. This system has all great components but none of them work well together. The sound is WAY to forward and bright. It just sounds horrible to me. The Alpine speakers driven by an Eclipse 5000 head unit in my Jeep sounds much better and costs half of what the PPI amps does in my M3.

So I've reconfigured the system to save weight (I autoX) and hopefully change the sound. I'm running an old school Hafler mse88ti amp bridged to the front and a Soundtream Ref. 404s power the rear fill and sub which is easily removeable (BSW enclosure). I set the headunit crossover at 80hz. I'm not 100% of the brand but the front consists of a passive three way setup with a 5.25" metal midbass, a 3" metal mid, and a 1" metal tweet. I'm now convinced it is the speakers causing the bright sound and not anything else.

What is a good affordable system that will fit the stock E36 locations up front?