I have some Seas Lotus 8" woofers Im installing in the front doors of my VT commodore sedan soonish, but I'm not completely sure how well they'll work just mounted in my doors (granted theyve been deadened and sealed). I only need them to play down to around 70hz or so. Ive been doing some research and read a fair bit about Aperiodic membrane enclosures. Should I need to resort to this or should the speakers sound fine without having an AP setup? I'll be using the speakers in a 2-way setup, they'll be playing up to around 2khz or so. My goal is primarily SQ not SQL, but I'll be able to feed them around 75rms

Specs for the speakers are:
Powerhandling: 150/300 Watts
Frequency Range: up to 2500 Hz
Sensitivity(1W, 1m): 87 dB
Nominal Impendance: 4 Ohms
Voice Coil Resistance: 3,2 Ohms
Voice Coil Inductance: 0,60 mH
Force Factor: 8,7 N/A
Free Air Resonance: 32 Hz
Piston Area: 220 sq.cm
Moving Mass: 51,88 g
VAS: 31,9 L
QMS: 2,39
QES: 0,41
QTS: 0,35

Cheers

You'll have no issues, if there the RW220's, as from reports they are quite comfortable playing down to 40-50hz and still maintain fantastic output.

Theyre the CW21EX001 8" drivers

Just checked it on the Seas site, and combining the specs you listed, it's xmax performance etc... I think getting a strong low end performance will be the last thing likely to bother you.

strong low end performance isnt really the only goal of AP door enclosures anyway.

I say read up on them, it looks very easy to make a DIY AP mat, but much harder to tune the thickness/breathability to get a good response.

Why not contact some of the more senior members/installers who've actually built these before: DD PHil, Proclass, abmolech etc. they should be able to point you in the right direction.


then just do it mate. Take a leaf out of Zion's book. The home install pussies on this forum would be blown away i reckon (and yes, I'm one of those pussies too). if it doesnt work, what have you lost? also remember however that AP enclosures are very inefficient, so you'll probably need quite a bit more power to keep up with the rest of the front stage. At least, thats what I read somewhere when I was considering the same thing....

Yeah Ive read efficiency is lost, which is a concern cause amplifier power is somewhat limited, and my tweeters are fairly efficient already.

My main concern is about installing these into my front doors, whether a door thats sealed and dynamated will act enough like an enclosure to keep them happy.

First thing I'd do (if you haven't already) is have a very good look at the specs and tech sheets of those drivers.

8" drivers typically don't play well much above 1khz, especially off axis in a car door.

As for bottom end response in doors, I'd avoid it if you can because:
1) The driver typically won't play as low in doors as it will in an enclosure (air leaks, etc)
2) Even if the door was sealed, door volume is typically up around 30L - if not correctly modelled first, oversized enclosures can lead to inballanced bottom end response depending on the driver
3) Even if you do get away with both of these factors, and you do manage to get a mid playing down flat to 70hz in your doors, the amount of rattles and extra resonances you will encounter will struggle to make it all worthwhile.

So in short, given a choice I'd say go an enclosure over a car door any day of the week - dont know a whole lot about AP enclosures (i.e. don't actually know what they are), however even a standard sealed enclosure will give better results most of the time then a car door will, even with the limited volume.

I'd honestly suggest if you can to place your focus on midrange performance rather then bottom end extension of the mids - limited extension can be countered for reasonably easilly (good tuning, higher crossover points, etc) but if your midrange sucks, then it sucks and their isn't a while lot you can do (short of hammering it with EQ, which I wouldn't recommend).

Definately try to get some response data on the 8" drivers (if you haven't already) before getting them, as they may not be well suited to a 2-way setup. Off the top of my head, I can only thing of one 8" mid that plays reasonably flat up to about 2khz and that is a Peerless model (HDS Exclusive) - even then, i'd be concerned about higher frequency distortion.

Personally, I think you could get similar results out of a good 6.5" / 7" driverin terms of bottom end, only with a better upper midrange and less install headaches!

Up to you though

Like all 8's, these will be privy to beaming BUT they have fantastic distortion figures all the way up to ~3/3.5k. From what I can remember, the breakup node is around 3.5k, but with a low playing tweeter and a notch filter, thats no problem. The Excels have phenomenal midrange capabilities, and the low end is about as stupid as any one driver can get. Deadening of the door is a must. These are perfect for a 2-way set with a good tweeter.

You can try AP just to be different, and the Excels have quite good specs to run them, but all that extra efforts isnt really worth it. If I were to run AP, it would only be for one of two reasons. First is to drive down through Fs, because I want low end extension. The other would be space, as running AP means I can get a MUCH smaller enclosure with the same dampening response. So unless you want either of these reasons, or you just want to be different (in which case, do it to your subs, not your midbass) then IMO its not worth the effort.

Yeah I researched these drivers before getting them, and they appear very able to play fairly high quite cleanly as well as a fair bit of down low oomph. I tested them a few days ago on a baffle board I had set up (filter only to play above 700hz) and they were able to play upto 2.5khz quite well, although best results were achieved with them slightly off axis (say 30 degrees) so thats the angle Ill be setting them up at in my doors. The tweeters Im using are Vifa XT25s (mounted in the A pillars), I've had them running set to a 2.5khz cutoff on a 24db slope and they seem to be handle that without issues.

As for AP I wasnt too keen on the idea to begin with, and as this stage I have no desire to be THAT different, I'm just after a nice clean sound. With a Fs of 32hz it seems it'll have no trouble playing down to around 60hz in my front doors (hopefully).

I don't have anything except an extremely basic equaliser (basic headunit fare) so I need to get my install 100%. In the long run if I do need to also include a dedicated midrange would it be better in my kicks or just halfway up the door (inbetween woofer and tweeter). Door would be harder than kicks but Id be worried about pathlength differences with them in the kicks. Also does a midrange need to be mounted in a seperate enclosure to the woofer?

Pathlength difference tends to be best with kick mounting, and worst with top of the door mounting. Get out a tape measure and see the differences, as ofcourse, it will change in each car.

If the midrange is a sealed unit (some include 2/3 DLS mids, Morel, Dynaudio) then no, it will not need a seperate enclosure, or an enclosure at all. If the mid is not a sealed unit, which is most cone mids (Focal, Rainbow, Peerless), then yes, you will need a seperate enclosure.

Isnt it better to have the midrange closer to the tweeters than the woofers? Ive looked at the kick panels in my car, they seem like an extremely poor position, theyre right next to the pedals and as you sit driving the car the lower half of the dash half blocks them (at least how I drive).

Anyhow hopefully the woofers will play cleanly enough as is so I don't need to go 3 way, as who can afford it this time of year?

Those woofers will be more then enough for your needs.

Take note though, you dont need the woofer to be within viewable distance of you to hear them. Using the environment for your advantage is part of car audio, and how the pro's end up doing things.

Mounting your tweeters near your woofers is the shortcut way, but not exactly true. Mounting them away will require a bit more understanding on acoustics, but when done properly, is very effective.

Cheers.

Im going to start a "my ride" thread tonite and post up a few pics of the install sofar.

I'd say your best results if you go three way would be tweeters and mids both in the pillars, with midbass wherever you can fit them (as close in distance as possible) and preferably not in doors (if it's at all avoidable).

Personally, I'd never run midbass drivers in doors myself, but given the complexity involved in other alternatives, many choose to stick with doors for the sake of simplicity. Far from optimal though.

Just oiut of curiosity - given the depth and diameter of the drivers, will you actually be able to realistically fit them in your doors at 30deg off axis? Just curious

The XT25's do have issues with distortion below about 3.5khz, but depending on your experience with audio you may not notice it.

Remember these are the Lotus models here - I've read they are based heavily on the Excels, but it's possible that their performance may vary. I've yet to see distortion or response data for these specific models.

Also remember that while the Excels have a good reputation for midrange potential, they also have a great reputation for being exceptionally difficult to work with. Whilst Peerless and Scanspeak products are typically pretty good out of the box, the Seas are known to need quite a bit of taming to get them to a good level.

Also, if the response graphs are anything to go by, the midbass performance of the Excel mids is abysmal at best. In the case of my Scan gear the Response graph characteristics are almost perfectly consistent with actual real world (i.e. in-car) characteristics.

I've no idea how well Seas graphs reflect real world performance, but based on the graphs alone they seem to get real weak below 700hz, and above 700hz they seem to require exactly 30deg off axis to beo good (on axis they look to be highly peaky, and at 60deg they seem to get erratic and lose capabilities above 2khz).

Not sure how closerly the Lotus units relate to these, but if those response curves are at all accurate they look like one hell of a pain in the ass to get them sounding good.

The door skin in my VT protrudes into the car a few inches, combined with service wholes in the door already I should be able to get them to mount fairly close to 30degrees.

If you prefer not to install midbass drivers in the doors where do you rather then be? I cant really think of anywhere else you could get the required volume for them to play in.

As for the XT25's, honestly my audio experience really isnt that extensive, to my "untrained" ear theyre doing a pretty decent job.

This whole setup is my first real forray into SQ, and though my setup isnt optimal by far I really couldnt expect it to be, especially considering Im stuck to a very strict budget.

Muzzy Seas drivers are a brilliant example of how graphs can't always tell the whole truth, because Seas drivers and especially the the Excel range (these appear to be based of the old W21EX001 excel range) are known for some of the best midbass output you can get, beat by a smidge only by the Scan Rev range. Completely the opposite to what the Seas graphs appear to show, especially when compared to something like the Peerless HDS (5.5mm +- peak xmax) which appear to have great midbass on paper but when placed in a real world enviroment are straining at best to keep up with the Seas (12mm linear and 19mm peak). Graphs are great but unless you take the other figures like xmax into comparison it doesnt tell the whole story I think you'd find the Seas drivers to have great midbass output and with even more midrange output, whereas the HDS would have acceptable midbass output with a nice linear midrange continuance, of course place these drivers into a car environment and the midbass ability will come in handy and once placed off axis (most setups) the very bright midrange of the Seas driver will hopefully be toned down a bit.


<a href="http://www.seas.no/images/stories/vintage/...04_w21ex001.pdf" target="_blank">http://www.seas.no/images/stories/vintage/...04_w21ex001.pdf</a>

<a href="http://www.madisound.com/catalog/PDF/peerless/830884.pdf" target="_blank">http://www.madisound.com/catalog/PDF/peerless/830884.pdf</a>

Luke

P.S. I actually just found out why the Seas drivers all appear to have quite rough FR's partially is due to the fact that the are measured in enclosures (most other driver brands measure free air) and actually have a 6db baffle step shown in there response graphs, something which won't be apparent in alot of other drivers FR's due to the fact that they account for this in the FR etc... I'd take this as Seas being extremely honest in the way there drivers may behave in the real world. Goes to show being able to read a graph is great but unless you know the exact way those measurements were taken, you're going to be guessing at best as to there in car performance since it can make it very hard to account for the measurement techniques when trying to apply that FR to your situation.

^^ Agreed Luke. I've heard the Excels in an old mates Orion setup (plans from Linwitz's website) and the midbass is stupid. Think Rainbow kickbass but snappier, more authority and can easily go lower. A lot must be said for the Aluminium cone when its done well (and the Rainbow's only have poly plop cones from memory!!).

Knowing HOW the FR graphs are measured goes a long way to understanding them. Not everything is what it seems (plus Seas measures at 0.5m, whilst Tymphony always measured at 1m from memory. BIG difference)

I've done several systems with exotic midbass/subs up front.

A Civic we did used 8s in the doors with AP mats, I also did a VL Walkinshaw with 8s in the kicks, with AP mats venting through the floor with Gortex.

Both worked really well, but considering the effort I'd say I've had as good results from "normal" door installs, or sealed enclosures in the kicks / floor.

By far the best so far though is our demo ute, but it has 12s in the floor for midbass.

Phil

Fair enough, as given the reputation of the Excel drivers I've always been a little weary about fully trusting their graphs.

I wouldn't say they are more honest with their graphs though - if they represent real world performance as poorly as they seem to (i.e. a massive bottom end weakness which - by reputation - isn't there in the real world) then it doesn't give a very good representation of real world performance.

Seas seem to be the odd ones out with their mids, as they seem to be the only drivers in which the responses don't really accurately represent real world sound. I've noticed with many other brands (such as Focal, Morel, Dynaudio, Scanspeak, Peerless, etc) all seem to very accurately reflect real world performance in their graphs.

I'd have to agree with you that bottom end performance of the Peerless HDS range isn't spectacular, however i wouldn't say it's because of their xmax purely. You mentioned the Revelator having a stronger bottom end then the Excel, but the Revelator's only have about 1mm xmax over the Peerless (6.5mm or so). Unless you mean the 22W/8851 Revelators which have about 9mm xmax - but i wouldnt recommend these for midrange use.

I really would like to hear one of the Excell's to hear how they sound for myself. They (along with the HDS Exclusive) seem to be amoung a very select few 8" drivers that are competent at producing a solid midrange. Given that everyone seems to love them, I'd assume so many 'experts' couldn't be wrong... but then again in this day and age that's a dangerous assumption to make.

The Rainbow Kick-bass drivers are available either in Profi (paper / natural fibre cone) or Vanadium (aluinium cone) form in their highest level of dress. They are also available in SLC range (fibre cone from memory) and CMX Power guise (aluminium cone - but not sure if they are they are available here).

Indeed aluminium cones do have their strengths, however they also have their weaknesses. Typically lower distortion characteristics, but cone breakup typically makes them more difficult to get good results with.

If only someone could make a bloody perfect material ...

Well I started on the pods for these this avo, pretty much its just a MDF/Fibreglass setup that fits where the factory 6.5" space is, and enlarges it to 8". Doesnt look like I'll get that 30 degrees, simply not enough leg room on the drivers side for the bottom of the woofer to stick out that far, but its a much better angle than what the factory provides. Only thing Ive noticed that MIGHT be a problem is the magnet on the Seas driver takes up nearly the entire hole in the door for the speaker to vent into. Is it very critical that the woofer has plenty of space to vent into the door? Its not a tight fit really but its probably only got a 10mm gap or so between the magnet and the door frame.

time to pay a visit to Mister Dremel...

Damn those flamin' dremels!

Something tells me I should not be cutting the door metal

We say you should

Dont cut the metal. its not safe, its not legal, its not nessescary
peace
Cyberpunky

x2

do the install properly.
If you do cut the metal, it will have to be reinforced, and an engineer's cert. provided.

^Just like the hole in your battery tray for cooler pipes

Door sheet metal isnt exactly structural.

That said it still remains illegal

Yeah I avoided cutting the metal by sacrificing a LITTLE bit of angle on the speakers, that said they still sound pretty good.