Subwoofer Install Issue

[Justin Pammer]

Hi.

I have a 2006 Lexus IS 250 AWD and had a Memphis subwoofer/amp installed in the trunk. It sounds pretty nice, but makes a terrible noise whenever the car is turned off. The installer could not figure out how to fix this and installed a toggle switch so that I could turn the sub off before turning the car off. I would like to come up with a better fix that doesn't require manual intervention.

I have the luxury package that comes with the Lexus 13-speaker Premium Sound System.

To my knowledge, the issue stems for the fact the amp turns off AFTER a signal is sent through the system whenever the car is turned off. It's this signal that is being picked up by the amp and amplified through the sub. Any ideas?

[CrunchySkippy]

Where are you getting your remote power signal from? Presumably the amp does not stay on after the power to the car is cut off, right? Check this first by turning off your car and seeing if the power LED is on at the amp.

Perhaps you can find a schematic of the factory amp and splice into the switched line source there. If you can't get a schematic (I don't really know how you would), you could always get out a voltmeter and start testing (I'd use the closest wire harness to the factory amp so you're not stripping/breaking wires needlessly while testing.) You'll want to find which wire sending voltage when the radio is "on" but no longer sends power when the radio of "off". Both test should either have the car running or in "Aux" mode, as this will eliminate the constant power. You can use any available ground on the car for your negative lead. Have an assistant help you out up front by pushing the volume knob off and on while you check the wire harness.

Sorry I can't be more specific...I don't know anything about the factory system in the IS. It should be noted that this all just my "best guess". I don't even know where the factory amp is located...

[Justin Pammer]

Thanks for the response.

Let me clarify the circumstances a bit. The noise does NOT occur when the head unit is powered off, but only when the entire car is powered off. There is still 12V supplied to the remote lead to the subwoofer amp for about a second after the engine on/off button is pressed. This is enough time to pick up this audible "signal" that is emitted. Consequently, there is still power supplied to the amp when the car stereo is off. So, turning the car stereo off and then turning the car off results in the same issue.

I suppose the only way I'm going to resolve this is to get my hands on the wiring schematic as you suggest. I don't know if this is possible or not. Potentially I could purchase the complete shop manuals, but those typically cost hundreds of dollars...

[CrunchySkippy]

Can you clarify if the amp is still powered on when the head unit is off? I can't tell if you mean the amp stays on for only a few seconds after the head unit is turned off -or- if the amp stays on indefinitely (until you power off the car).

I'm still trying to determine if you, in fact, have a remote lead tied into your head unit or if the installer simply hooked it up to a switched power supply (probably from the fuse box). Find out where the remote lead is tied to. That will eliminate some of our problem solving.

We know the factory system doesn't suffer from a "power down pop", so you just need to figure out how the factory amp gets its signal. (Let's hope its not computerized version...)

[Justin Pammer]

Yes, the amp still has power after the head unit is turned off. My suspicion is that the installer tied the remote lead to the fuse box directly, but I don’t know because I haven’t had it apart yet. I’ll get back once I can confirm this.

[old timer]

Check your ground. Your electrical system and all of the components connected to it are ground to the chassis of the vehicle. It sounds like when your installer connected the ground wire to the chassis he picked a place that was not ideal, or did a poor job of attaching the wire to the spot chosen as the ground point. Double check the spot and the quality of the connection.

Your amplifier stores energy in small amounts and uses the energy when necessary. All amplifiers have small capacitors built into the electronics; these capacitors store energy until needed. When the stored energy dissipates once the electrical system is shutoff it is not being released correctly because of a faulty ground. Most people installers included do not understand or do not care (installer) about the importance of a proper ground.

If you check all of the connections and are still having this problem you may just have a faulty amplifier.

Just a Thought

Old Timer

[Justin Pammer]

I confirmed that the remote lead does indeed run to the fuse box. This is probably not the best way to have this wired as mentioned. I found the factory amp in the trunk on the passenger side. It's very accessible. I'm trying to get my hands on a schematic, but if I can't the voltmeter route sounds like a viable option.

Old Timer: The ground looks good, very solid. Overall, the installation looks professional. I had this installed at a custom car audio place and aside from this one problem, the job is quality. I believe I tested your theory by cutting off power to the remote lead connected to the amp car still on. There is no "popping", the amp shuts down quietly. In fact, this is essentially what the on/off switch does that the installer provided when he failed to resolve this issue.

CrunchySkippy: In your last post, you mentioned "Let's hope its not computerized version". I'm not sure I understand what this implies. Are you saying that if it is computerized there won't be a simple on/off 12V DC lead but rather a digital signal that communicates instructions to the amp?

Thanks for all the input.

[Scott M]

I confirmed that the remote lead does indeed run to the fuse box. This is probably not the best way to have this wired as mentioned. I found the factory amp in the trunk on the passenger side. It's very accessible. I'm trying to get my hands on a schematic, but if I can't the voltmeter route sounds like a viable option.

Old Timer: The ground looks good, very solid. Overall, the installation looks professional. I had this installed at a custom car audio place and aside from this one problem, the job is quality. I believe I tested your theory by cutting off power to the remote lead connected to the amp car still on. There is no "popping", the amp shuts down quietly. In fact, this is essentially what the on/off switch does that the installer provided when he failed to resolve this issue.

CrunchySkippy: In your last post, you mentioned "Let's hope its not computerized version". I'm not sure I understand what this implies. Are you saying that if it is computerized there won't be a simple on/off 12V DC lead but rather a digital signal that communicates instructions to the amp?

Thanks for all the input.

I think Old Timer may be on to something.

When I did the Home Theater install in my house, I had a horrible super low frequency rumbling noise coming from my sub-woofer, but only when everything was powered off.

When power was on, the sub worked perfectly and the rumbling noise was gone.

I went through everything (drove me nuts) and it turned out to be a bad ground plug.

I replaced the ground and the problem was resolved.

[smooth1]

are you using the factory head unit? If so, does it have a sub out or how is the amp connected to it?

I guess I'm trying to understand this signal thing you talked about after the car is turned off. Why then don't the other amps pick up that same signal? I think you have a connectivity issue.

[CrunchySkippy]

CrunchySkippy: In your last post, you mentioned "Let's hope its not computerized version". I'm not sure I understand what this implies. Are you saying that if it is computerized there won't be a simple on/off 12V DC lead but rather a digital signal that communicates instructions to the amp?

I really don't know how the factory amp gets its signal to power down. I was hoping it was the traditional method of current being sent down the remote line. But my reference to a "computerized" version was that there could be another way...maybe signals via pulses of sound/power/etc. There's a lot of things I don't understand...like fax machine initiation protocol's!

I still believe you need to source a signal from the factory head. Either from the factory amp or another accessory.

Perhaps a brain storm of the forum users will produce other sources to tap into. Does anyone know if our cars has an external CD changer option? (It may be outdated technology.) Too bad you don't have a power antennae!

[Justin Pammer]

I finally got this issue resolved over the weekend. Thanks to everyone for their input.

It turns out there were multiple things wrong with the installation that led to this issue. I had this installed at a place called Sounds Deluxe in Clarendon Hills, IL. I wasn’t planning to disclose the installer (or the butcher as I now like to refer to him), but after what I found (and what I paid), I felt I had no choice.

To answers a few questions posed earlier in this thread…

• I have a 2006 Lexus IS 250 with Navigation System / Parking Assist (Rear view Monitor) / Lexus Premium 13 speaker audio. Nothing has been modified on this vehicle, except the addition of this sub.

• I had a Memphis subwoofer amp (Memphis 500:1) installed, with a Memphis 12” dual voice coil sub. This is a mono amp, but requires both a right and left input signal.

So, what was wrong?

• The left input signal going to the Memphis amp was tied to the tweeter of the left rear door. Subwoofer amps have a very hard time amplifying frequencies in that range.

• The right input signal going to the Memphis amp was tied to the woofer of the right rear door. Slightly better than the first bullet, but still incorrect as the Lexus factory amp does not send the lowest frequency ranges to the woofer’s found in the doors, it reserves those frequencies for the down firing sub found in the trunk.

• The right input signal’s polarity was reversed. Yes, that’s right, reversed. Slowing turning the gain up on the amp actually REDUCED bass initially as it was cancelling out the factory sub.

• The remote lead to the sub was pinched into the fuse box by a fuse. I can’t remember exactly what it was connected to, but it doesn’t matter because it was incorrect.

The net affect of all of this is a very weak and unusable input signal to the Memphis amp which means the input gain and the bass enhancer (the bass enhancer can be thought of as kind of a volume control on the amp) had to be at MAX to get any bass at all. Enter the rumbling noise when the car was shut off… Any noise at all on the input end that falls in the 20-200Hz range is going to shake the earth since the amp is set to max output.

The fix:

Simple really. I took the car apart until I could get at the factory down firing sub in the trunk (you have to get at it from the back seat, but not really that hard). Now you know exactly which wires need to be tapped and can easily deduce the polarity since you can actually see the connections going to the speaker. The butcher spliced line after line trying to find the correct ones. Unfortunately, I found all of his damage, and some of the splice marks weren’t even taped! How could you ever figure out what the correct wires were from trial and error? There’s like 60 wires in each bundle! More than half probably aren’t even for the audio system. Madness.

The second part of the fix was to tap the remote lead into the correct line. I took CrunchySkippy’s advice and used a voltmeter to test each line leading to the factory amp until I found what I was looking for. Basically, it breaks down like this: There are four connectors going to the factor amp. The first has four wires, two are “always on” 12V signals and the other two are grounds. The second connector is for speakers. The third connector (which has much finer wires leading to it) is the one of interest. And the fourth is more speakers. So back to the third connector… This connector encompasses all the leads that tell the amp what to do. For example: turn on/off, volume up/down, equalizer adjust, etc. There are two orange leads that go to this connector that will work nicely for tapping in the remote lead.

After all these modifications were made, the gain on the amp is at about 5% and the bass enhancer is at 0. So the rumbling/popping is completely gone when the vehicle is shut off (or inaudible). The new remote lead tap probably helped too. And the amp sounds MUCH better as it doesn't have to struggle so hard to produce bass.

In hindsight, I never would have done this if I know it was going to turn into such a mess. The butcher assured me that he knew what he was doing, but I think it’s safe to say that wasn’t the case. It’s a bit nerve racking to have a $40,000 dollar car in pieces in your garage.

BTW, I was also able to obtain a schematic of most the wiring in this model IS if anyone is interested (got this just after I figured stuff out the hard way). I have it as a hard copy right now, but can scan it in if there is interest.

Again, thanks to everyone for their help.

[jrobsea]

Did you have to run a dedicated power lead all the way from the battery, or is there somewhere in the region of the trunk that you can tap off of without overloading the circuit?

Assuming you had all this info up front, would you just do it yourself next time? I don't mind paying a bit for a professional install, but I don't like the idea of paying hefty fees for a hack job. I'd rather do it myself than have an amateur do the install.

I appreciate you sharing your experiences in this thread. I've been considering adding a subwoofer since I got the car, but I hadn't heard how difficult it is. It sounds like it's fairly simple as long as it's installed properly.

[smooth1]

this isn't about "look at me", But in the 01-05 IS 300 forum, I posted the install I did called audio revamp project in the Dream Ride thread. that install took me a day and a half.

If your adding any audio gear or changing anything out, you really have to know what your doing, or else you end up with the first post in this thread.

I feel for ya man. Do it yourself?-Am I a pro???

Have someone else do it?- Are they a pro???

I was in the audio biz for quite a few years, so it was never a question about whos gonna do the work on my car, But I have heard alot of stories worse than yours about letting someone else do the work also. Atleast you have the brain cells to figure out the problem and fix it the right way. Most others would have been relagated to the stupid switch thing. Hats off for the recovery... :)

[Justin Pammer]

Did you have to run a dedicated power lead all the way from the battery, or is there somewhere in the region of the trunk that you can tap off of without overloading the circuit?

Assuming you had all this info up front, would you just do it yourself next time? I don't mind paying a bit for a professional install, but I don't like the idea of paying hefty fees for a hack job. I'd rather do it myself than have an amateur do the install.

I appreciate you sharing your experiences in this thread. I've been considering adding a subwoofer since I got the car, but I hadn't heard how difficult it is. It sounds like it's fairly simple as long as it's installed properly.

Yes, you must run a dedicated power lead directly from the battery to the amplifier. It's usually a very heavy wire (mine is 0 Gauge). This was done correctly and so was the grounding of the amp with the initial install, so I didn't have to modify this. When I was initially troubleshooting this issue I followed this lead from front to back. It does not look that difficult to install. There is a very convenient hole in the firewall to get the lead through and running it to the trunk would just require removing the lower door jam trim on both driver's side doors. The rest of the run goes behind the back seats which you will need to remove anyway.

If I had all the information up front, I might not have done it at all. I say this for a couple of reasons: I rarely work on cars and I'm a bit intimated to work on something this complex (which is why I hired someone in the first place). I always had this fear that I was going to fry the Nav or something. And it is impossible to not break some little plastic clip somewhere (I broke three during my adventure - make sure you have epoxy on hand). Lastly, I don't know what this does to my warranty, but I suspect bad things.

If you're serious about doing this, let me know and I'll post more detailed instructions along with the schematic on a new thread.

[jrobsea]

Did you have to run a dedicated power lead all the way from the battery, or is there somewhere in the region of the trunk that you can tap off of without overloading the circuit?

Assuming you had all this info up front, would you just do it yourself next time? I don't mind paying a bit for a professional install, but I don't like the idea of paying hefty fees for a hack job. I'd rather do it myself than have an amateur do the install.

I appreciate you sharing your experiences in this thread. I've been considering adding a subwoofer since I got the car, but I hadn't heard how difficult it is. It sounds like it's fairly simple as long as it's installed properly.

Yes, you must run a dedicated power lead directly from the battery to the amplifier. It's usually a very heavy wire (mine is 0 Gauge). This was done correctly and so was the grounding of the amp with the initial install, so I didn't have to modify this. When I was initially troubleshooting this issue I followed this lead from front to back. It does not look that difficult to install. There is a very convenient hole in the firewall to get the lead through and running it to the trunk would just require removing the lower door jam trim on both driver's side doors. The rest of the run goes behind the back seats which you will need to remove anyway.

If I had all the information up front, I might not have done it at all. I say this for a couple of reasons: I rarely work on cars and I'm a bit intimated to work on something this complex (which is why I hired someone in the first place). I always had this fear that I was going to fry the Nav or something. And it is impossible to not break some little plastic clip somewhere (I broke three during my adventure - make sure you have epoxy on hand). Lastly, I don't know what this does to my warranty, but I suspect bad things.

If you're serious about doing this, let me know and I'll post more detailed instructions along with the schematic on a new thread.

Thanks. I'm not eager to remove seats and trim panels on my car. I might hold off until I find a local installer who's got some good references for an IS250 or 350 and have it done by them.