28 replies to this topic

[Luke352]

As muzzy suggested cut lower, there is no reason why a 4" mid shouldn't be able to play down to 200hz cleanly and preferably you want it to go up to 6k or thereabouts. The thing with your midrange is if it can play those freq's use it for them as it is the driver you want to cover the broadest freq range possible to help keep all your imageing cues coming from the same driver aswell as keeping issues like phase coherance as far as possible out of the most sensitive ranges of your hearing.

Here is a test of the 4" exclusive which suggests a cross point of 300hz but also points out that in a car environment there shouldn't be any issues going as low as 200hz. http://www.diymobile...hread.php?t=617

Also one for the trius (vifa/peerless TG9) 3" vs legatia 3", if you decide to go a bit smaller.

[vtviper]

Kickpanels seem the way to go then. I did look at the seas mids, but I only found 1 available on www.sealotus.com.au and thats a very expensive unit, well and truly out of my budget right now whereas the peerless HDS 4" is spot on nearly.

and yeah the 8"s provide some AWESOME kick. considering I have the amp power Im seriously thinking of bridging an amp and giving them 150wrms instead of the 75 they're getting (and loving) now.

[muzzy66]

The reason I recommend crossing the midbass lower isn't that I don't think it can handle midrange duties (the seas 8" are known to be impressive in this regard), but more for the sake of making tuning easier.

Personally, I always aim to have the midrange handling the widest range of frequencies it comfortably can. Out ears are less sensitive to midbass frequencies, so the lower you cross the mids:
1) the easier it will be to blend the midbass
2) the less critical midbass location becomes (as it's only playing 200hz - 300hz and down).

I wouldn't worry too much about actual position of the drivers - what I'd look at is distance. Pull out the trusty old measuring tape, and try to find a location where the midrange and tweeter distances are as close as possible to being equal.

Remember that sensitivity is measured typically at 1m, and a driver with a 92dB sensitivity at 1m could easilly have a 97dB sensitivity at 1/2 metre. Note also that you need to double power to increase sensitivity by 3dB. The result in theory is that as you increase power, one driver pay potentially increase in audible output more rapidly then the other - the result being that the system may sounds 'ballanced' at one volume and then overly bright (if tweeter is closer in distance) or overly warm (if mid is closer in distance) as volume increases. This is only one more 'theory' of mine that I've not had a proper chance to test - however I did notice that the sound ALWAYS seemed better ballanced as the tweeter and midrange locations got closer to being equal.

May or may not be worth taking into consideration

Position is less important.. other theory is that if all of your different sound signals are well ballanced (i.e. equal in output and neutral in response) and of an equal distance, then your ears will not be able to logically seperate the tones and thus localisation won't be an issue. Yet another theory I've not been able to properly test, but all experimenting I've done so far has suggested this.

This is why my next install plans (which won't be for some time) are to keep the tweeter and midrange as close as possible to each other, and then mount the midbass pretty much anywhere as long as it is of a similar similar distance.

Hope these ramblings help

[muzzy66]

P.s.

If you do run the 4" peerless PPB driver (830870) try to run it 30deg off axis, and cross it over no higher then about 3khz, and no lower then 200hz. This should bring best results

If you can somehow run it completely on axis, you can cross it up to about 4khz hapilly but i wouldn't go much higher.

The Nomex version is better controlled, but extremely difficult to find - I don't even know if they make them anymore as a 4".

The Exclusive 4" is better again, but harder again to find. I was personally looking around everwhere for it, and general suggestions are that it is discontinued.

The Focal 4KSlim also appears to be quite a nice driver, but not quite as nice as the Peerless drivers.

As for giving more power to your midbass drivers, it depends what you are after. If you are seeking a ballanced sound and overall harmony, then your aim will be to get equal power to every driver and then use the head unit's active crossovers to adjust the levels according to relative sensitivities. If you seek some emphasis in the bottom end, then you can give more power to the mids however it won't just increase punch/kick, it will also exhagerate lower vocals and give an unnatural boost on lower bass guitar notes, etc.

If you go with more power, but then end up ballancing them out with gains anyway, then my personal opinion is that it's not necessary. Only time I consider more power to be needed is if your current system (as a whole) isn't loud enough (or requires high gains settings to make it loud enough) - then I'd suggest increasing the amount of power to every speaker in order to be able to reduce gains and get a cleaner signal

Edited by muzzy66, 13 March 2008 - 09:38 AM.

[~thematt~]

I think we'll need to clarify a few things, with some scientific principles so we dont get ahead of ourselves!

Postion is important. How much? Very. Why? Because of the different responses in the near field, as opposed to the far field. Is it as important as pathlength differences? Absolutely. More? Probably. Why? Because pathlength differences only need to be ~30cm or closer in difference to achieve a singular coherent image from two wavefronts. Greater then that, and you'll start getting multiple images, or simply just no image at all because its too diffuse. With positioning, its actually quite critical.

Lets try to understand why.

Near field and far field are two distinctly seperate regions of space, that exist at certain distances away from the polar radiation of a driver. It is based primarily on frequency/wavelength. At 1kHz, its around 0.5 to 1 metre. Closer to a speaker then these distances, and your in the near field. Further away and your in the far field.

So what does this mean for me? Well, in the near field, the primary source of information is the direct wave. In fact, environmental responses have almost no effect at all. If you're clever (and you'll need to be really clever) you can manipulate the environment in the near field to benefit you in the far field. In this zone, intensity is almost equal everywhere. So getting closer to a speaker whilst its playing in the near field doesnt actually make it louder.

In the far field however, environmental responses override the direct wave as being the primary source of information cues. Reflections, refraction, resonance etc. all contribute quite greatly to our perception of sound. And intensity drops off quite quickly. Its 6dB per metre for anachoic conditions, or 3dB per metre for 4pi steradians (think a baffle).

Our tweeters are in the far field. The range of frequencies they play make this a given. In theory, we want BOTH the mids in the near-field. In practice (to achieve 30cm pathlength differences) they'll be in the far field. THEY BOTH NEED TO BE IN THE SAME FIELD TO ALLOW FOR SYMMETRICAL TUNING!!!! You CANNOT have one in the near field, and one in the far field, without a super-duper processor (note: none that powerful exists in Car Audio). Therefore, you MUST NOT mount them in your doors. Otherwise, you starting a 100metre race 200metres from the start line, and will never be able to get to the finish line in time.

The other thing to keep in mind is phase relationships, and sensitivity of the driver. Sensitivity (and the intensity changes when you crank the dial) is taken care of quite easily by matching the gain on your amplifiers (with a DMM/Osciliscope, impossible by ear). With phase relationships, if you have a tweeter playing 'midrange' frequencies (like below 5-6kHz Xover) it will have its own image, and therefore should be mounted within 1/4 wavelengths difference from the mid. This will allow it to be tuned so that you get a strong stable image, and not multiple ones.

If you use your midrange for midrange duties, and tweeters for higher frequencies (as you should in a 3-way), then you can mount your midrange down low, and the tweeter up on the dash and tune to allow the precendence effect to pull your stage up. Just make sure your tweeter is located either on equal pathlengths to the mid (same distance away) or further. Intensity is the key at such high frequencies, and time alignment will not help you.

One more thing. Before you buy a driver, study it. Find out what the cone is made of, and where the breakup nodes are located. A 4" peerless (like the HDS Nomex or Exclusive) use poly cones, and can play up to 4-5kHz easily without nasty breakup. The Seas can also play high, but its breakup is much more noticeable (from what I remember, its around 6-7k) and should be avoided (Xover lower) due to its stiffer cone.

Given the fact that all drivers experience beaming, you can get polar radiation right up to their beaming point (off axis and on axis has the same response). For ANY 4" mid, that means you'll easily push 5kHz without off-axis problems (domes go higher).

So in short, what does that all mean? 4" mids mounted in the kicks are the best, with tweeters in the kicks or the dash/pillars. Environmental response is a major consideration for these units (not the midbass anywhere near as much) and therefore start thinking about the environment MORE then what type of driver to use.

And for Seas drivers, try here....
http://www.madisound.com/catalog/index.php...88d349e92927637
The Mid is $170 US each.

Edited by ~thematt~, 13 March 2008 - 11:21 AM.

[Luke352]

If I remember correctly your in the brissy area arent you vtviper? have you considered coming along to the comp this saturday http://www.mobileelectronics.com.au/forums...539049&st=0 it's a chance to have a listen to some nice cars, and get some input on how your system is going at the same time.

[vtviper]

Didn't even know about the comp until now. Works been cancelled for that day so I might make the trip out, though won't be competeing cars a mess but it would be great to hear some SQ greats and train my ears a little.

In regards to those seas drivers, the W12CY-003 ($160us rrp) looks attractive, a bit larger but should pose no problems if kickpanel mounting (most likely now). How would it compare to the peerless though? its very hard to audition these drivers, the peerless can be had locally for cheaper but I do like the idea using more seas speakers as all have been impressive so far. Either way with a 3.5khz cutoff I'll assume my vifa xt25's can play the low and stay happy?

I understand its better to have the one speaker play the widest band it can and cutoff the midbass lower, but I am somewhat limited in my useable crossover filters here. If i cutoff my midrange around 300hz, Id lose the ability to run any low cutoff on the midbass at all (only high pass it). Are there any inline active crossover filters available on the market without having to resort to equalisers? my JL amps only have high pass OR low pass filters, so bandpassing is difficult at the moment.

[~thematt~]

The Seas drivers have a very very close tonality to your current midbass unit. Similar motor design, similar cone profile etc. etc. You'll be hard pressed to tell the differences tonally. Compare to the peerless? Well, the peerless has a poly cone, so its breakup nodes are less evident and it has a more forgiving sound (read: less detail). The poly in the peerless isnt anything special, so its strength is okay but not super-duper. This translates to impact not being as visceral (like the sting a Seas can deliver). The sound can be said to be 'smoother' and 'warmer' as a result. The Paper cone peerless is also like this, but more so.

Think of it this way. Paper is at one end of the scale, and sounds warm whilst going 'thud'. Metals like Magnesium and Aluminum are at the other end of the scale, have move detail (can be 'thinner') and go 'snap'. Poly is in between. Seas is comparable to Scanspeak, and peerless is a cheaper version of Scan, so IMO the technology employed in the Seas is head and shoulders above the Peerless, but at a cheaper price, the peerless is more cost effective.

When you crossover, dont use 4kHz specifically, and because you are getting a good mid, dont go below that. Aim for around 5-6kHz. That way, your mid is playing the mid frequencies, and your tweeter is playing the highs. Otherwise you'll get problems like I mentioned before.

There are active filters on the market, yes. They are from Audiocontrol. Hit their website up for a gander at some of their products. Far superior in control to what you've got now, obviously. And quite cheap too.

[Luke352]

vtviper, on Mar 13 2008, 03:02 PM, said:

Didn't even know about the comp until now. Works been cancelled for that day so I might make the trip out, though won't be competeing cars a mess but it would be great to hear some SQ greats and train my ears a little.

Yeah come along, introduce yourself at the little tent thing and if Dan is around he's sure to point out some of the rest of us. You can always enter novice just to get some judgeing feedback, there not going to have a bitch about the car being messy on your first comp. But even if you don't want to enter thats fine, we always like to welcome people coming along even if it is just for the social aspect and to hear some other cars etc...

Luke

p.s. sorry for the OT people

[vtviper]

Awesome can't wait. Won't compete this time, but if anyones willing to have a listen to my system I'd appreciate some feedback.

Also considering some car audio type midranges instead of the usual home stuff. I see Morel CDM54's for say all the time, and being a small 3-4" diameter would mean I could potentially mount it next to the tweeters. I know dome's arent very useable below 500hz.
Also been recommended dynaaudio dome midranges as well, same size as well (think theyre 6ohm tho, but very efficient). Any opinions on these? Other advantage of the above drivers is that theyre far easier to find for auditioning.

[BMWTurbo]

vtviper, on Mar 14 2008, 09:32 AM, said:

Awesome can't wait. Won't compete this time, but if anyones willing to have a listen to my system I'd appreciate some feedback.

Also considering some car audio type midranges instead of the usual home stuff. I see Morel CDM54's for say all the time, and being a small 3-4" diameter would mean I could potentially mount it next to the tweeters. I know dome's arent very useable below 500hz.
Also been recommended dynaaudio dome midranges as well, same size as well (think theyre 6ohm tho, but very efficient). Any opinions on these? Other advantage of the above drivers is that theyre far easier to find for auditioning.

CDM88's are smaller then the CDM54's, not sure if this is of concern to you though. I believe there will be a car with CDM54's in it there Sat

[mooingchicken]

yer thanks bmwturbo

yer im running 3-way morels, using the 54's, your welcoem to have a listen. just ask me on saturday.
also the factory x-over for the morel midrange is 300hz.

[BMWTurbo]

http://www.morelhifi.com/products/mob_alig...cross_mx33.html

300Hz 6dB high pass on the CDM54's from the Accuset MX33.3 Crossover.

Edited by BMWTurbo, 14 March 2008 - 01:33 PM.

[Luke352]

I've got the DLS UR2.5 aswell which is similar to the CDM54, which you can hear and compare the differences.