The "final" Subwoofer Replacement Question?

[mikee72]

if you run the 1ohm amp to a 2ohm sub you will most likely burn the amp up and not be able to play it at all. a new sub will hit lower (around 5-7hz) with out distortion, that is unless it has a foam lip.

Hmm...that's the first time I've heard of an amp burning up from a "higher" numerical ohm load. Usually amps have a minimum ohm load that they will play down to, not a maximum. Where did you get this imformation?

[southernsc300]

it has happened to me 3 different times. but it wasnt a one ohm difference. it was 4 on one account, and 2 on the others. the first time i had a blaupunkt amp with 2 10" jlw0. the blaupunkt heated up within about 20-30 minutes and then shut off. after it did that twice it completly burned out. the other 2 times when the stuff started to over heat i just scrapped the systems. the blau was 4ohm the subs were 8ohm.

[mikee72]

it has happened to me 3 different times. but it wasnt a one ohm difference. it was 4 on one account, and 2 on the others. the first time i had a blaupunkt amp with 2 10" jlw0. the blaupunkt heated up within about 20-30 minutes and then shut off. after it did that twice it completly burned out. the other 2 times when the stuff started to over heat i just scrapped the systems. the blau was 4ohm the subs were 8ohm.

There are a myriad of ways you might have hooked up that amp that those two subs, depending on whether you had them in series, parallel, amp bridged, dual voice coils, etc. I'm going to go out on a limb and say that you had them hooked up in such a way that it created an ohm load that was numerically less than the amp was rated for. Unless the Nak in our cars is somehow different than 99.9% of the amps on the market, there is no harm (other than less volume) in running a higher numerical ohm load than the amp was rated for. In fact, it's actually better for it, since amps produce less power as impedance goes up. That's why amps are rated "down to" x ohms and not "up to" x ohms. This really is common knowledge in the audio world. The fact that the ohm numbers of the speakers and the amp are different by themselves make no difference. It's the result of the two after wiring that determines whether it's "Good" or "Bad" for the amp. That's why it's called an "Ohm Load." :whistles:

[redsully]

As for my stereo, I chose a 6 channel in 5 Channel out Alpine V12 Amp. It runs Cerwin Vega Fronts and rears and 2 12" Cerwin Vegas in the trunk. It sounds really good, but the bass is a little heavy to any listener in the back seats. The driver's and front passenger's bass level is perfect, but I do occasionally hear my gas sloshing around. I'm going to sound-proof it when i get more time.

[AWJ]

I have no idea what you guys are talking about. Aside from speakers and wiring. I had no idea this thread got so dang huge! I'm going to have to read it from page 1 when I get some time. Maybe I will be able to wire my own sounds after that. I usually don't fuss over it though.

I must say, the Cerwin Vega set-up seems bad !Removed! though. I'm trying to catch a sponsorship for some a/v stuffs. It's not quite working yet though. Need more visibility.

[SPORTcoupe300]

Mikee: You're right about the higher resistance in the Rockford probably not doing any harm to the amp, but I didn't reccomend it for 2 reasons:

1) There is the remote possibility that the amp will not like such a high resistance

2) The speaker will produce less than half the sound the original did....so what's the point.

I turned up the gain on my amp a bit today.

I am SOOO impressed with the lows.

Got a few rattles as it gets into the 50+ hZ but down low it sound damn beautiful.

If I turn the gain up above about 70%, I get a weird whining noise in the speaker.

No problem though.....the gain is at 50% now and it thumps good.

Next step: Dynamat

[OKSC3]

He is right about the impedance of an amp, you can run an 8ohm single voice coil speaker off a 1ohm amp, its not going to hurt the amp, but you will sacrifice current.

[mikee72]

Sport, do you have any pics of the amp install? The reason I'm so anal about the aftermarket amp situation is that I've heard that Lexus does not offer a replacement stereo harness if you hack yours up. HEARD is the operative word, so if I'm wrong, please correct me. I also don't want the amp to be seen when you

look in the trunk.

I just don't like things that look like they've been "hot-rodded," if you know what I mean.

If I've followed you correctly, you're still running the stock amp for the rest of the system. One of my other "beefs" with the stock system, is that the 4" mids cause the sound to be "peaky," that is, the tendency to get loud on certain high notes, due to the 4" tendency to want to reproduce high frequencies easier. This being the case, I'd like to also replace the stock 4's in front with 6 1/2's. I've read somewhere that the amp receives a filtered signal from the head unit for the mids. In your experience with this system, so you know if this is the case?

[SPORTcoupe300]

Mikee: My amp is mounted behind the carpet stuff and is completely invisible from the trunk.

I'll get a picture within the next few days, but just so you can picture it, if you open your trunk and look to the left, there is a spot where you are supposed to have a medical kit (most people don't have it).

My amp sits snugly behind that.

It's held down by 1 direct screw, 1 metal bracket piece(custom made), and 1 zip-tie.

I know this doesn't sound too secure, but trust me, I've whipped this car around many times and the amp is solid.

There is no need to touch any stock harnesses. The only thing you'll need to do is cut the wires coming to the stock 10" and get them to your amp.

As for your mid issue, I've found that the sub now produces enough low to balance it all out and I'm happy with the way the system is now.

So to answer your question: I have no idea whether the 4" are run by the amp or directly by the headunit.

I'm pretty sure it's the amp though.

Right now I have my Bass and Treble both turned to 75% and it sounds very nice.

This system (I have Premium, not Nakimichi) is one of the best stock systems I have ever heard.

It was a little weak in the bass department and I have taken care of that.

Now I do not feel the need to do anything else to it.

[mikee72]

Mikee: My amp is mounted behind the carpet stuff and is completely invisible from the trunk.

I'll get a picture within the next few days, but just so you can picture it, if you open your trunk and look to the left, there is a spot where you are supposed to have a medical kit (most people don't have it).

My amp sits snugly behind that.

It's held down by 1 direct screw, 1 metal bracket piece(custom made), and 1 zip-tie.

I know this doesn't sound too secure, but trust me, I've whipped this car around many times and the amp is solid.

There is no need to touch any stock harnesses. The only thing you'll need to do is cut the wires coming to the stock 10" and get them to your amp.

As for your mid issue, I've found that the sub now produces enough low to balance it all out and I'm happy with the way the system is now.

So to answer your question: I have no idea whether the 4" are run by the amp or directly by the headunit.

I'm pretty sure it's the amp though.

Right now I have my Bass and Treble both turned to 75% and it sounds very nice.

This system (I have Premium, not Nakimichi) is one of the best stock systems I have ever heard.

It was a little weak in the bass department and I have taken care of that.

Now I do not feel the need to do anything else to it.

Ah ha! If you don't have the Nak system, the only amp you have in the back is a sub amp, according to http://www.technicalhelp4u.com/ The Nak system is complex and has three differnent plugs that go to the amp. This means that those of us with the Nak system will have to run both amps, so I'll have to run a new power wire. I'm still not clear about how you get the signal for the "remote" turn-on without interfacing with the stock wiring. Ditto for power, unless you ended up running new wires.

[SPORTcoupe300]

Mikee: I did run a separate 10 gauge cable for my amp.

For the remote turn on there are infinitely many places you can hook it up.

If you are gonna run a separate power wire (highly recommended), might as well run the remote turn-on alongside it.

To find out where to place it, get a multimeter and check some places on the fusebox while the ignition is on and while it's off.

The remote turn-on wire needs a 12Volt signal.

As long as it's 12 volts, it doesn't matter where it comes from.

For mine, I used one of those blue electrical taps to tap one of the wires coming to the stock amplifier, so my amp turns on when the stock amp turns on.

One thing I like to do is put a switch on the remote turn-on wire in case I want to listen to the music while the car is off without draining the battery too much.

[mikee72]

I found this searching another forum, on the subject of adding an additional amp:

"No speaker adapter is needed. The inputs to the circut board are RCA from the head unit wire direct to a rca male plug.

The power cable is not that difficult to run, you do not need to run a remote or inputs since you can tap these from the sub amp or the NAK amp depending on which you have."

What the heck is he talking about? I didn't see anything resembling RCA plugs anywhere in the wiring diagram.

[ChicagoLexus]

bought my rfz3410 today anything i need to know about the install? Remove the sub then the copper support for it right?? Didnt get it yet, just want to prep.. I think I'm going to throw the sub in then have a shop run the amp... what would be an appropriate cost?

[SPORTcoupe300]

Chicago: Check your PM

Mikee: Where did you get that piece from?

He's probably talking about an aftermarket head unit there.

Anyways, here are the pics you asked for:

Cover on

Cover Removed

Closeup of bracket

Zip Tie

If you want to see the pics in more detail, check my car in the "garage"

[mikee72]

Free beer for Sport!

I quoted that bit from Club Lexus audio forum. Most of the folks over there disgourge using the hi-level inputs. You said that you tried that, and that you got lots of whine/noise from it. Does the RF amp list a range of how "hot" of a signal it can withstand?

[SPORTcoupe300]

Thanks.

I'm not sure what the limits are on the voltage the RF is designed to receive but for me, using the high level inputs worked much much better than the conversion to RCA.

There was a lot more whine with the RCA converter, even after I added a ground loop isolator.

The other annoying thisng with the RCA converter setup was that the amp would only pick up loud thumps in the low frequency range.

So when I was playing music, the sub would only hit on the hardest notes (sounds terrible)

I like when the sub is constantly doing something (enriching the music instead of hitting once every few seconds)

The only noise/whine I get now is when I turn the gain(output volume) on the RF to over 70% but this is no problem since it produces enough juice at 50% gain.

[Autofanatic]

i haven't read all of the posts here, but i think that i have the perfect solution to the sub replacement problem. i have just finished building a box that i have fitted up under the rear deck, where my stock sub was, and i have fitted a JL 8W7 in exactly the same position as the stock sub. the box i made came out to be around .9 cubic feet, and is perfect for the W7. this sub is unbelievable, both for sound quality and output. i am using a JL 500/5 amp that is powering JL's 650 CSi's in the front, infinity kappa coax's in the back, and the 8W7. i have pictures of the entire process if anyone is interested, but i must forewarn you....THIS IS A TIME CONSUMING PROJECT!!!

[2XLexV8]

Good Evening,

I replaced my Nak sub with a Punch z RFZ3810.

You'll need a Poineer sub for the bracket.

With the new sub on the Pioneer bracket, it fits perfect.

The NAK sub is 5 ohm, I used the 8-ohm R-F.

The stock amp sounds a lot better, but those who want real bass will need more amplification.

Good Luck.

[mikee72]

Good Evening,

I replaced my Nak sub with a Punch z RFZ3810.

You'll need a Poineer sub for the bracket.

With the new sub on the Pioneer bracket, it fits perfect.

The NAK sub is 5 ohm, I used the 8-ohm R-F.

The stock amp sounds a lot better, but those who want real bass will need more amplification.

Good Luck.

Hmm... my stock sub in my nak system is 1 ohm. Printed on the back of the magnet plain as day. Are you sure about yours being 5 ohms? My car is bone stock.

[mikee72]

i haven't read all of the posts here, but i think that i have the perfect solution to the sub replacement problem. i have just finished building a box that i have fitted up under the rear deck, where my stock sub was, and i have fitted a JL 8W7 in exactly the same position as the stock sub. the box i made came out to be around .9 cubic feet, and is perfect for the W7. this sub is unbelievable, both for sound quality and output. i am using a JL 500/5 amp that is powering JL's 650 CSi's in the front, infinity kappa coax's in the back, and the 8W7. i have pictures of the entire process if anyone is interested, but i must forewarn you....THIS IS A TIME CONSUMING PROJECT!!!

By all means, post those pics! Let's make this thread the definitive SC sub thread!

[mikee72]

This *might* be what some of us are looking for:

http://www.installer.com/wires/index.html

I'll email them to see exactly which system this works with, and what functionality is lost from the stock amp.

[SPORTcoupe300]

If they mean for you to power your amp by that tiny 20(ish) gauge wire, they're on crack.

Those wires aren't meant to hold more than 5 amps.

The average 300Watt amp draws almost 20amps.

Run Separate power and connect the ground to the frame of the car.

With the knowledge that the remote turn on can be any steady 12 volt source that is off when the car is off, you can get pretty creative.

As I mentioned before, it's up to you how you want to wire the remote turn on.

I usually get it from my ignition and put a separate manual switch on it.

This way, I can flip the switch to turn off the amp if I want to listen to my radio while the car is off (key must still be on ignition).

As for the inputs for the amp, if the amp is good quality such as the RF, using the High Level Input should be fine (Mine sounds great)

I am strongly against that little harness.

[mikee72]

Well, I think most of us would rather Plug n' Play using a harness, if we had the choice. The kicker, is that since I posted that, I have leaned with reasonable certainty, that filtering is done at the amp level, meaning that I replace the entire Nak with a large 5-channel, I'd be able to let my future 6 1/2" in the doors play down to where I like them. I had previously thought that the stock HU sends two sets of signals (hi/low pass) to the amp, meaning that replacing the Nak amp wouldn't allow me to lower the cutoff on the mids, so there would be no point in messing with the mid part of the system.

[Theodore]

Back for another Opinon.

I hope you guys are happy all this talk about systems got me all geared up desiging my system as we speak.

What im doing?

Pioneer Free Air sub Max 500 watts go to crutchield amp pusing it will be a MRDM500 Alpine about 500 rms keep it low and cool. 3ont ever clip.

Now the secret guys............... Doesnt matter how many boxes or subs matters on location and how you hook it up. To get awsome bass outta the smallest speaker you need this tool called an epicenter. There on ebay. What this does it allows you to equalize the bass make it louder deeper etc. NOT an EQ but an EPICENTER. Very usfull. Will give off nice bass from affar.

AND dont forget your radio should have FOUR VOLT PRE OUT. To get the maximum quality out of ur AMP. If your using an HI/Low to power your sub . Thats a No No. But if there is no option, and you dont wanna change the radio. Then go with a FOSGATE AMP that has a BUILT in HI LOW IMPENDENSE CONVERTER>

Hope this helped out. sorry for the long message figured it would go with this long ASSSSSSSSSSSSS thread.

[SPORTcoupe300]

If your using an HI/Low to power your sub . Thats a No No.

But if there is no option, and you dont wanna change the radio. Then go with a FOSGATE AMP that has a BUILT in HI LOW IMPENDENSE CONVERTER

Thanks for you input Theo.

You're right, the best input to the amp should come in 4V RCA flavor, but we were talking about changing just the sub (stock head unit)

I'm plenty happy with the mids and highs, but there wasn't enough bass for me.

I don't want to put in an aftermarket HU because I like things looking stock.

Like I said before, I tried the external converter (from high level speaker wire to low level RCA) and it performed miserably.

I then figured out that RF's high inputs worked very well.

If I wanted to make my stereo really nice, yes I'd swap out damn near everything, but I'm pretty happy with the rest and I'm pretty sure there are at least a few people in my shoes.