After about three months of staring at the RMB-8 I've had on my shelf(compliments of the cookie monster:p), I finally decided to throw the sucker in. I had some issues along the way though.


I first hooked it up using the line level leads that go to the factory amp. This setup made the speaker work fine but when I turned the HU off, I would get a most pronounced transient signal spike causing the speaker to POP . Not ACCEPTABLE.

So I went out and got hold of an RCA trigger off pop eliminator. This thing is designed to cut the rca signal when it senses an off signal from the HU remote wire. IT DID'NT work. I'm guessing that the transient is being sent a split second before the power is killed to the trigger circuit. I went back and hooked things back up to the the factory sub and found that if you stick your ear close to the sub you can here a very faint pop. So, it stands to reason that if you hook the same signal to an after-market amp, that faint pop would turn into something nasty.

What now? Well, I noticed that the "other" four speakers don't have the same problem, so why not take advantage of the built in cross-over of the sub channel in my 5 channel amp. I went to Radio Shack and bought two Y-connectors and split the rear speaker input leads between rear and sub to the amp. BINGO! No turn off pop.

But Iggy,,,,,,,,,,,,,,,now when you fade to the front your sub will fade as well. It don't matter in this case, because when I did the EQ bypass that is how it how it WAS. It's actually not a bad deal for me when I have the kiddies in back sleaping on a long road trip I can fade the whole kit and kabootal to the fronts for me and the wife. The JL's don't have that much of a low end punch when they are on their own in this instance, but it works great with sleaping kids. However.......when dad is on his own with all five working and a little volume..........look out!


Anyway, I set the x-over to about 80HZ(whitch is a good non-directional high freq. cutoff) and it seems to work pretty well. I realize this speaker was intended to be a mid bass and not a true bass sub, but I did some isolated tests with the factory sub alone and the Kicker alone and I must say the Kicker is a vast improvement over the factory POS. In my limited experience with this stuff, if you add a few more watts to a sub, it may not add much more volume but it will add a more depth.

Like drcookie said:
------------------------------------------------------------------------------------
With default settings on the amp. I can defintely hear the bass coming from the back; a lot better than the crappy, cheesy stock sub. However, the new sub does not provide as much PUNCH as the enclosed 10" or 12" subs that take out some space in the trunk. Hey ! it's only an 8" sub and it's IB.
Anyway, the current for the input line from the HU is pretty low, I have to boost it up by cranking up the gain and the boost step to +12dB on the new amp.

So, the conclusion is:
In my opinion, the project is well spent and worth every single penny. I am not a heavy bass listerner. So the bass provided by the new sub is more than enough for me to enjoy the music/radio.

Keep in mind that this is a mid bass sub. It does not give you deep bass frequency below 35Hz and it will not kick your seat or shack your rear view mirror. But, it will give your a better, tighter, and cleaner bass compare to the stock sub.
------------------------------------------------------------------------------------


Anyway, I'm still looking for a setup where I can mount a "true sub" under the rear deck with minimal fuss. Until then, the RMB-8 is the way to go.

That's my story and I'm sticken' with it.

Iggy

ps- how's that for a write-up southy?

 

Iggy,
That was a grade "A" write up. I find that you can't ever provide too much information about a subject that is interesting or pertinent to a specific install or problem. I know I ramble on to the point that most people probably quit reading... but if they are REALLY interested in the subject or it pertains to some trouble that they have gotten into, I'm sure they're happy for all the clack-yack that they can get.

I'm still bone stock with my electronics... just listening to the four upgraded Polks in the doors. You were wondering why the stock amp seems to power up with the ignition key even when the HU is off? I can't really think of any reason either, except that it doesn't hurt to have it on without any signal. Maybe it's one of those Class D amps that takes some time to bias up and there would be an obnoxious delay between the time when you turned on your headunit to the time that you actuallly heard clean music???? Sounds like you've gotten around it in any case.

I have a question... What impedance is the Kicker RMB-8? The stock subwoofer is like 1/2ohm. What would happen if you drove the RMB-8 directly from the stock amp? Would it not produce enough output level? Or would it be another easy mod for someone like me, who doesn't want to tear into the electronics quite yet? How hard of a mechanical install is it? Does it physically fit without major grief?

Contrats on yet another triumph over the BLOSE system! You are persistent and methodical about your troubleshooting techniques. Good deductable reasoning powers.... Must be a life of too many checklists

Take Care!
Southy

 

Hey, all:

I too am using the Kicker, and have experimented with a range of settings on the crossover.

Just a thought, but you might want to try bringing up the bottoms of the door speakers to maybe 110 or so, and also the 8" up to 150+...............

For me, it seemed to let the midbass handle more of the frequencies it was designed for.

Just my .02!

John