View Full Version : M7 Frank-N-Polk Revisited
01-23-2006, 08:41 PM
I have been told that the best way to isolate the mid/bass driver (now only midrange) from the (new - to be added) woofer is to shoot expanding foam into the top half of the enclosure inside a plastic bag. This is supposed to be done after positioning a .3 cuft box behind the mid bass driver and relying on the foam to ultimately hold the box in place.
In conjunction with the obvious required Xover mods, this sounds like a reasonable plan to me. Has anyone else had any success with this kind of a mod?
01-23-2006, 08:51 PM
Not much success with mods like this... better to either start from scratch with a new diy speaker and leave it alone. It has been built to specs according to the enclosure it's in now. If you start messing around with the cabinet and internal volume it will greatly alter what it'll sound like. (probably for the worse)
01-23-2006, 08:52 PM
why not take that same 0.3 cu ft box u're talking about, and countersink dowl recesses into the edge of the 0.3 cu ft box and the cabinet itself... then dowel + woodglue = quality work.
expanding foam will throw you're whole enclosure size out of wack, besides, it acts like poly-fill.
01-23-2006, 08:53 PM
How many posts do you have to make, to get the SAME answer?
We don't BUTCHER classic Polk speakers here, jackass. Even if you were to modify it, whomever gave you the advice posted above either is a total f$%king moron, or simply pulled the idea out of their rectal cavity, baited the hook, and watched you jump on the line like a retard.
I have an idea, get some of the expanding foam, and shoot it in your piehole. Report back with your findings.
01-23-2006, 08:57 PM
Pretty funny stuff there Russ.
1) The idea behind a passive radiator is its kind of like a port. Well, not really. But lets run with that thought for a minute.
With a port, its a specific size to get a tune down to the midbass. In a sealed enclosure, the enclosure is also a certain size to get a certain tune out the midbass/woofer. Ok...follow? Now a passive radiator is kind of like a quasi sealed/ported speaker. It has the pluses of a port with none of the draw backs.
You might be expecting this insane amount of bass or something, but those speakers were just not designed for that application, they are designed behind the idea of truthful reproduction to the music.
2) A passive radiator is designed around working with the midbass. And when I say working with I mean the midbass doing all the muscle work and the PR being the slave. The PR does not control the midbass, and you putting an active woofer in the enclosure that was designed around a PR would be a bad thing. The midbass may move to much, distort due to to much pressure in a sealed enclosure designed around something entirely different...
Modding the speakers to utilize an active driver is stupid, wrong, and destroying a great pair of speakers. Don't do it.
Thats about as serious as I can get with this one... hopefully you know why eh.
01-24-2006, 12:11 AM
01-24-2006, 01:24 PM
passive radiators/drivers are another form of 'iso' mount ... just as the clamshell is popular, so is the passive radiator. the result is double the moving mass, but also double the displacement (outside the box) due to the second driver not being directly coupled to the first. it's an intricate design, and i agree, it shouldn't be fooled with. want to build your own and mess with it? fine.. but don't destroy something that's already working.
01-24-2006, 02:11 PM
oh poor little monitor 7's, we hardly knew ye!
01-26-2006, 01:36 PM
Putting a active speaker in a sealed enclosure with midrange drivers will overheat the midrange drivers and blow them. I even tried to put tupperware behind the midrange drivers to create a small sealed enclosure for them but even this didn't work as the tupperware was not rigid enough.
Just wanted to add this as it seems we have discussed the midrange distortion issue but not the physical damage issue.
PS- My mother is still looking for those bowls... LOL
01-26-2006, 01:59 PM
that's it - i'm going back to car audio...
Im officially looking for a new hobby...
And not to mention... Im thankful I did NOT get a job at CC... dealing with THIS all day...I would pull my hair out...and when I ran out...I would go after the customers...beatches!
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