Stereo FAQ (2 Viewers)

[LBridges]

That isn't right.

....

My suspicion is that the Geek Squad was confusing terms a bit. ...

I agree the Geek Squad would be confused - a little knowledge is dangerous - I'm proof - ask me (not really) about 100 series maintenance foibles.

Unregulated power amps (most on the market, Alpine, Pioneer, etc.) produce output power that scales with the voltage coming from the battery/alternator. Tightly regulated power amps (some JL Audio, old Xtant, others) keep a constant power output regardless of the voltage of the power source.

Does a CD play louder or softer if it's running off just the battery (maybe 13.6V) vice the alternator (maybe 14.4V)? Nope. The RCA inputs/outputs are not in the power stages and except for serious power fluctuations (enough to cause the unit to malfunction) are not subject to variation in output that tracks with the source voltage.

 

[PabloCruise]

I agree the Geek Squad would be confused - a little knowledge is dangerous - I'm proof - ask me (not really) about 100 series maintenance foibles.

Unregulated power amps (most on the market, Alpine, Pioneer, etc.) produce output power that scales with the voltage coming from the battery/alternator. Tightly regulated power amps (some JL Audio, old Xtant, others) keep a constant power output regardless of the voltage of the power source.

Does a CD play louder or softer if it's running off just the battery (maybe 13.6V) vice the alternator (maybe 14.4V)? Nope. The RCA inputs/outputs are not in the power stages and except for serious power fluctuations (enough to cause the unit to malfunction) are not subject to variation in output that tracks with the source voltage.

Okay, I guess I will pick a unit and go pre-amp out to the Nak amp so as to minimize the wiring...

 

[Iocaine]

Wow! Very interesting... I wondered why Crutchfield would not support our LX470s! So even though the RCA outputs are designed to be pre-amp outs, they can change enough to blow the very amp they plug into? Interesting... Did the Geek Squad make it sound like alternator output varies just over the RPM range to blow the amp?

Did you replace the sub or any speakers? Or just head unit?

Thanks!

I didn't touch the speakers or the sub. No need to yet.

The Geek Squad guy stated he sat with a voltmeter on the RCA outputs and noticed a change in output voltage as the engine RPMs increased. No real reasoning given. Just the only thing he noticed out of wack. He stated he called their "guru squad" and after a ten minutes they came to the same conclusion and Best Buy stopped doing LX installs shortly thereafter. He also stated that it was the only one probably twenty of his installs to blow the factory amp in the 13 years of his installing. He has only seen four come back with blown amps as well and all four were with very low end HU's and seemed to be very regional. He actually stated a specific store in Greenville SC, that had numerous poor results?

Also remember that RCA outputs are designed for RCA inputs.. NOT speaker inputs as the Nakamichi has. Maybe after market amps have resistors installed in the inputs?

Food for thought.. If one could gauge what the correct input voltage to the Nakamichi is, it is theoretically possible to put resistors inline between the RCA and the speaker line outs, before the split to speaker wire. This would give a consistent voltage flow?!?

 

[LBridges]

...

The Geek Squad guy stated he sat with a voltmeter on the RCA outputs and noticed a change in output voltage as the engine RPMs increased. No real reasoning given. Just the only thing he noticed out of wack. ...

I guess maybe I wasn't following along carefully enough - this is with an aftermarket headunit being attached to the OEM amp - correct?

The tech measured RCA out voltage while music was playing? To measure voltage levels in music would normally require use of an oscilloscope and repeated play of the same passage.

With a single steady tone? I wonder what difference he saw - voltage will normally go up and down with the loudness of the music so a small difference would have no effect on an amp. A large difference would suggest a headunit that is defective or a model one should avoid using as they have improperly designed the output section of the pre-amplifier.

I wonder... if the headunit output was very high (say 6 volts) and an OEM amp expected a very low input (say 1.7volts), if the resulting clipping would be enough to overheat & kill the transistors in the OEM amp's input section.

BTW, the outputs from a headunit RCA normally fall in the 50-500 Ohm range, while the inputs to an amp are typically around 10,000 Ohms or higher. Unfortunately I no longer have my OEM amp in order to measure it's input impedance and determine if the OEM system followed this convention.

 

[PabloCruise]

I didn't touch the speakers or the sub. No need to yet.

The Geek Squad guy stated he sat with a voltmeter on the RCA outputs and noticed a change in output voltage as the engine RPMs increased. No real reasoning given. Just the only thing he noticed out of wack. He stated he called their "guru squad" and after a ten minutes they came to the same conclusion and Best Buy stopped doing LX installs shortly thereafter. He also stated that it was the only one probably twenty of his installs to blow the factory amp in the 13 years of his installing. He has only seen four come back with blown amps as well and all four were with very low end HU's and seemed to be very regional. He actually stated a specific store in Greenville SC, that had numerous poor results?

Also remember that RCA outputs are designed for RCA inputs.. NOT speaker inputs as the Nakamichi has. Maybe after market amps have resistors installed in the inputs?

Food for thought.. If one could gauge what the correct input voltage to the Nakamichi is, it is theoretically possible to put resistors inline between the RCA and the speaker line outs, before the split to speaker wire. This would give a consistent voltage flow?!?

I guess maybe I wasn't following along carefully enough - this is with an aftermarket headunit being attached to the OEM amp - correct?

The tech measured RCA out voltage while music was playing? To measure voltage levels in music would normally require use of an oscilloscope and repeated play of the same passage.

With a single steady tone? I wonder what difference he saw - voltage will normally go up and down with the loudness of the music so a small difference would have no effect on an amp. A large difference would suggest a headunit that is defective or a model one should avoid using as they have improperly designed the output section of the pre-amplifier.

I wonder... if the headunit output was very high (say 6 volts) and an OEM amp expected a very low input (say 1.7volts), if the resulting clipping would be enough to overheat & kill the transistors in the OEM amp's input section.

BTW, the outputs from a headunit RCA normally fall in the 50-500 Ohm range, while the inputs to an amp are typically around 10,000 Ohms or higher. Unfortunately I no longer have my OEM amp in order to measure it's input impedance and determine if the OEM system followed this convention.

I wonder what kind of low-end head units we are talking about? And have the head units gotten any better since '98-'07? These things are 18 to 9 years old now...

 

[PabloCruise]

It looks like the Kenwood that @Iocaine selected has pre-amp out voltage of 4v/10 kOhms and impedance of <600 ohms:

Specs | DDX372BT | Navigation and Multimedia | CAR ENTERTAINMENT | KENWOOD USA

 

[JMC5000]

Hello, I posted separately but trying again here since this thread has provided a lot of great info.. I have just had a new double DIN head unit installed in my 01 LC and its the type that the touch screen flips up to access CD/DVD port but the fit is too close at the top edge to allow the screen to flip up and out. My installer thought he would have to shave the top edge of the dash facia and I was not open to that just yet.. Does anyone know if the unit can be pulled forward just enough to provide the clearance? Or, would this not result in a secure installation..? Many thanks for any insight. JMC

 

[RobRed]

You should be able to pull the unit forward. I had a similar pioneer unit though it was a perfect from the get go.

post pics for better help.

 

[JMC5000]

I will try to take a pic that shows the as-is install. It's a Pioneer unit (AVH 4200-NEX) which, according to my installer does not require an installation mounting kit so I assume it just slid into the slot where the factory unit came out of but not sure what holds it in place. It should just need to come forward about 1/8" is my guess..

 

[RootMeanSqr]

I have the same unit. It's definitely tight. I had to loosen the mounting screws and move the head unit (up/down) to just the right place. Sounds like yours is a tad too high, doesn't take much to jam the actuation. Sometimes I have to use my thumb to move the trim to allow the Pioneer face place to move freely. A few actuations and it's okay, albeit a little slow sometimes.

 

[JMC5000]

Here's a couple of pics (the best that I could do) of the upper right and lower right corners. It's tighter at the top. I will try to loosen and adjust as noted. Thanks much, JMC

 

[Patineto]

Perfect Timing..

I'm installing a Pioneer AVIC-Z130BT, connected to a Infinite reference amp (newer speakers too).

I have the stock wire bundle of the Avic (the one from the avic has like 20 wires, the one from the land cruiser like 12) and also the RCA bundle but still confused (for the speak signal for sure) when you use one and not that other..

Also where do I get the wires for the speakers..?? from the two bundles that go into the OEM amp (Do they sell a female connector for the pigtails..?? do I take the amp apart or just take apart the pins at the connector under the seat, or do I rewire them from the doors..

 

[Patineto]

I've only used dynamat extreme in mine. I was able to get a great deal off of ebay.

Do you have a link, name of the company...??

 

[LEX]

@JMC5000 It looks way too far in. I have a similar unit with a motorized screen (AVH-X4700BS) and it moves freely like it should. I'd open it up and see if you can move it out some. Shouldn't be a problem if you're able to just a tad. I'll try to snap a pic of mine.

*edit*

 

[Docboy]

There's a 2003 LX470 I'm looking at purchasing. 2 things I'm looking at:
1) The subwoofer in the cargo area near the 3rd row driver's side is blown. Can anyone recommend a replacement? Crutchfield doesn't have the exact size, and the dealership wants $550 + $270 for an OEM. Any suggestions?

2) Not sure if this is right thread, but the DVD player in the cargo area/3rd row passenger side is shot, can't read DVDs. Is there a replacement also for this DVD player?

Apologies if this has been discussed before,

Thanks!

 

[Quick]

@JMC5000 It looks way too far in. I have a similar unit with a motorized screen (AVH-X4700BS) and it moves freely like it should. I'd open it up and see if you can move it out some. Shouldn't be a problem if you're able to just a tad. I'll try to snap a pic of mine.

*edit*

View attachment 1338403

Any pict of the dash to see how it looks and what year LX is it in?

Thanks

 

[LEX]

Any pict of the dash to see how it looks and what year LX is it in?

Thanks

'99 LC

 

[Patineto]

Sorry for the request..

MY 100 has no "Hole" on the thermal shield, so I do have a reference to where to drill the hole on the fire wall..

I guess is not a big deal, I can just make sure is nothing on the other side..

Thanks

 

[BillZ260]

For LC/LX's with Nav, I've seen a singe DIN unit added while keeping the Nav, but the install was done at a stereo shop. All the Nav sounds came through the new head unit and worked as normal.

If you Google Image Search "Land Cruiser Nav Stereo Install" the 5th link is a Youtube video to install of the pic below.

So this is doable, and it's my intention of doing so. I know I'll probably dump the stock amp, and the door speakers are shot so I'm not too worried about that stuff. To me, it seems like the hardest part will be making the little 'winglets' that fill the sides of the single din radio.

When I figure it all out i'll let you know, any help with the understanding of the interface between Nav and Stereo is appreciated. Thanks

Land Cruiser Nav Stereo Install

 

[JMC5000]

Reporting back on install of Pioneer AVH 4200 in '01 LC.. To LEX and others who provided knowledge and experience... Installer adjusted unit outward with a couple of washers behind mounting screws to allow motorized screen to flip up and out. All good. Thanks much.