6 replies to this topic

[Big_Valven]

I thought this might be a good topic for discussion on the forums.

I'm getting closer to using a 3" cone midrange in my car. I'd like it mounted up high, in an enclosure capable of getting it down to around 400Hz, even if not ruler flat, good enough to work with from an EQ point of view. Whether it's capable of this without distortion is another point, but it's where I'd like to start aiming.

The idea will be to mount them on the zero delay plane with their respective tweeters, with the mids in sail panel builds and tweeters on the pillars. That only leaves me with room to build an enclosure just big enough to house the midrange however, which won't achieve the frequency response I want.

I was considering using aperiodic damping or a flow resistor to vent down the sail panel cavity into the door trim. I know it's used for subwoofers but what do people think from a midrange point of view?

[syd-monster]

Its been done, but is a tune as you go style install. I mean, I don't know or ever heard of a program, table, chart or paramaters that help you make aperiodic membraned style enclosures.
The mechanics of it all still apply, your tuning/colouring the driver to effect the way it plays the sound. We all know, done right it can work well.

Keep going with this!

[SQXPRT]

If you can stretch to a 4", the Esotar² works great in 0.25 litre.

Otherwise, the AP for a 3" would need to be "experimentally" determined

[TMM]

I ran a setup like this on my sub (ported box lined with polyfill, and also in the port). It isn't so much a 'bigger sealed box' as just a ported box with an attenuated port. I don't think it would work that well if your enclosure is way too small in the first place - if neither ported or sealed will work for the volume you have, aperiodic isn't going to work either because it can only be somewhere inbetween ported and sealed. If ported will give you the extension you need but with a large peak in response, then stuffing the port will allow you to iron that out and achieve an enclosure that is 'just right'. That's my 2c anyway.

Personally i'd just make a sealed enclosure as big as possible, fill it with acoustic stuffing and work around the frequency response you get. Is it possible to have the enclosure extend into the cavity behind the door trim? As long as the part going from the sail to the door isn't too thin it should still act like one sealed enclosure. If that isn't an option then it can't hurt to try the aperiodic enclosure, worst case you just block it off and turn it into sealed .

Either way, porting or using a specific size sealed enclosure to extend the range of a mid probably isn't the best solution. There is no free lunch, anything you do to improve the bottom end of a mid will cause a phase shift, so you might just be better off cutting your losses and crossing to the midbass at a higher frequency.

Edited by TMM, 01 June 2012 - 03:33 AM.

[Lunchbox.inc]

There is no free lunch,

no no, i am completely free!

i would actually think thatAP would be a great way to go about it, i'm not 100% familiar with the use with wider frequency band drivers, only moreso with midbass/sub bass drivers, but with what you need to get out of the setup, i think AP would work quite well for, TMMs point isn't exactly what i would call true AP, just more of an attenuated port (as he said), AP should be able to give you a critically dampened driver, at the expense of senitivity, now i'm not 100% sure on the real world ramifications of a critically dampened midrange, as the cone moves so little in the first place, but the requirement of the tiny enclosure should definitely work to your advantage, and as a mid range is quite efficient to begin with, your not really going to be effected by that...

as other have said, the real world "tuning" of AP is alot more experimental than other enclosure styles, but i think it should yield some great results, especially in low end extension...

[Big_Valven]

Good responses so far. FWIW I'm not intending to make the poor little thing do more than it's capable of, perhaps more just wanting to give it the best chance it can get in the install

Definitely not able to stretch to an esotar unfortunately Pulse...

My thoughts keep changing, but with the right setup, taking the chamber into the door cavity / door trim would allow me to get closer to an IB arrangement if done properly. But I don't know if that would support my aims in terms of FR, I just haven't done midrange enclosures to know. But I would think that even AP would require the AP to 'vent' to a different airspace than the driver to work properly.

Maybe even some benchtop tests would be in order, to grab an RTA and do a nearfield comparison of an ideal sealed chamber versus experimental AP ones. To have time...

[SQXPRT]

Just think of the midrange enclosure as a smaller version of a sub bass enclosure... if it's too small, what can you do make it seem bigger?

(I use Bass Box for mids too) - *hint*