# Help! - Bypass Lexus IS Amplifier



## Dspencer (Sep 5, 2013)

I've been searching like crazy and having trouble finding quality information on the subject.

I know I can use something like the LC7i from Audio Control, or Bit-One, or 3.sixty.x from Rockford Fosgate (bit on the pricey side though), using the speaker outs from factory amp and summed by the LC7i or other unit.

HOWEVER, I've been reading that the factory amp enforces a 35hz subsonic filter that cannot be defeated (big bummer, as I plan to use 12" sub size minimum and don't want it unable to go below 35hz). 

Also, Tnutt19 was telling me he never was satisfied with the system sound, after trying many options, with his previous Lexus IS, using factory amp speaker outs as the source for his aftermarket equipment. The factory amp seems to do too much processing on the signal, including crossover function, delays, and such.

He offered the suggestion to install an aftermarket head unit where the factory cd/dvd changer is (under my NAV/touchscreen unit). He found a way to still keep the touchscreen/nav and other functions in play, by mounting the factory hu/source behind glove box.

This may be an option I'll go with. But, after consideration, I'd prefer to keep the stock dash area the way it is, if possible. If for no other reason, for stealth and cosmetics (I like the way it all looks stock - adding an aftermarket HU, because of how the area is stock, will look odd).

I've heard that someone figured out how to bypass the factory amp - using pre-amp signal for aftermarket dsp>aftermarket equipment. However, I cannot find this info anywhere after hours of searching around.

Please help!


----------



## [email protected] (Nov 7, 2010)

I would guess the problem is that the signal from the headunit to the amplifier is a fixed level, meaning you would have no volume control from your radio. If you used a DSP with its own controller that could control the volume. 

What year is the car?


----------



## [email protected] (Nov 7, 2010)

and which audio system does it have?


----------



## Dspencer (Sep 5, 2013)

2007 IS350 with navigation, non-ML.

Yes, I think I read somewhere that the stock pioneer built amp/processor, located in the trunk, processes the volume adjustment, along with crossover for speakers, and time delays. 

I wish this vehicle wasn't such a pain to upgrade audio for.

If I would be best off going with head unit replacement option, I did find some dash kits, surprisingly, to help install the aftermarket HU where the stock source unit/cd changer is. But if I understand correctly, I would have to keep the stock source unit (at least the board) and install hidden somewhere, so the climate controls work (climate control buttons/nobs are not on the source unit though - but I guess it somehow integrates in and processes the climate control function). 

I'm just trying to figure out the simplest way to upgrade audio for this car with the best possible signal to my aftermarket equipment - using dsp or LOC from the amp speaker outs, even summed, is going to mean some frequencies aren't there - I know below 35hz will definitely not be there if I went this route - and that is simply unacceptable. 

Thanks for any help/advice any of you provide!


----------



## Dspencer (Sep 5, 2013)

Since it seems the stock amp handles volume control, and bypassing for my system would mean the only audio control would be a volume remote from the dsp or amp(s), anyone ever figured out how to defeat the 35hz subsonic filter of the factory amp? If I could defeat that somehow, there will be no issue using a dsp post factory amp.


----------



## HiloDB1 (Feb 25, 2011)

Have you looked into the Beatsonic kits? I have an 01 LS430UL with ML/Nav. The Beatsonic kit for my car removed the entire factory hu and kept AC controls. It came with a module to retain the AC controls on the touch screen and even let me tap a signal into it so I could play video on it.


----------



## Dspencer (Sep 5, 2013)

HiloDB1 said:


> Have you looked into the Beatsonic kits? I have an 01 LS430UL with ML/Nav. The Beatsonic kit for my car removed the entire factory hu and kept AC controls. It came with a module to retain the AC controls on the touch screen and even let me tap a signal into it so I could play video on it.


If I can find one for the Lexus IS350, that will be a HUGE help!!  Maybe I need to get better at doing searches - I've had issues finding much on the IS350.

Thanks for letting me know this may be a possibility!!


----------



## thehatedguy (May 4, 2007)

Looked on my.is forums?


----------



## Dspencer (Sep 5, 2013)

thehatedguy said:


> Looked on my.is forums?


Yes, I've been all over the Lexus forums for months. I haven't read every single post, but I've used the search functions as best as I could and read the threads that seemed pertinent. 

In my own research today, I did find the beat-sonic adapter as mentioned by someone else, that may work for the IS350 - I need to contact them to be certain it will still retain all the oem functions. 

I also found axxess/metra parts that MAY do the job for an aftermarket HU install. I need to contact them as well, as it doesn't mention retention of climate controls - it will retain steering will volume controls and some others it mentions in the product description, but it mentions nothing about retaining use of oem touchscreen and other controls...

Either way, looks like $200+ just to get the adapters/units needed for IS350 integration for aftermarket HU and dash kit. The budget may have to stretch, lol.:laugh:


----------



## Dspencer (Sep 5, 2013)

Once I get all of this figured out, I'm going to post a new thread with appropriate keywords so others can find easily with search function in the future.


----------



## Dspencer (Sep 5, 2013)

Can anyone confirm if some of the DSPs on the market will help bring back the sub 35hz bass that the stock amp rolls off? 

My understanding is that the factory amp subsonic filter cannot be defeated, by I read somewhere that it may be possible to have the DSP boost the sub bass to compensate.


----------



## thehatedguy (May 4, 2007)

Well my IS300 wasn't that much of a pain...lol.


----------



## HiloDB1 (Feb 25, 2011)

I think pulling signal before the amp and its built in processor is going to be the best way to go. Pretty sure you can find wiring diagrams online and find the signal going into the amp and tap off of that.


----------



## Dspencer (Sep 5, 2013)

thehatedguy said:


> Well my IS300 wasn't that much of a pain...lol.


No doubt! :laugh:


----------



## Dspencer (Sep 5, 2013)

HiloDB1 said:


> I think pulling signal before the amp and its built in processor is going to be the best way to go. Pretty sure you can find wiring diagrams online and find the signal going into the amp and tap off of that.


Yeah, that is what I was thinking too...UNTIL I found out that the factory amp controls volume (not the source unit). In other words, I would lose all volume control (along with fade/balance, eek) using the stock knobs & touchscreen.

The only way to control volume then would be with a remote from the DSP, but that isn't ideal, and wouldn't include balance/fade - not to mention that my touchscreen would then be completely useless for anything audio system related.

I wish I could speak with the system designers for this vehicle and ask them why they decided the complicated system integration was a "good" idea...


----------



## HiloDB1 (Feb 25, 2011)

I think in this case youre better off with a new source unit and bypass the stock system completely.


----------



## Dspencer (Sep 5, 2013)

HiloDB1 said:


> I think in this case youre better off with a new source unit and bypass the stock system completely.


Yes, that may be what I have to do. BUT, then the use of the stock touchscreen, which is actually quite nice, is gone, and the total system budget will have to increase.

I'm hoping what I read about the ability of DSP to boost the frequencies under 35hz (to compensate for the factory amp filter) is true - that would be the best scenario as I prefer to keep the stock controls/look in the cabin. Either that, or I'll have to just do without the lowest bass frequencies...ugh


----------



## Dspencer (Sep 5, 2013)

Maybe I should just sell the Lexus IS350 and get another vehicle! :laugh:


----------



## HiloDB1 (Feb 25, 2011)

Dspencer said:


> Yes, that may be what I have to do. BUT, then the use of the stock touchscreen, which is actually quite nice, is gone, and the total system budget will have to increase.
> 
> I'm hoping what I read about the ability of DSP to boost the frequencies under 35hz (to compensate for the factory amp filter) is true - that would be the best scenario as I prefer to keep the stock controls/look in the cabin. Either that, or I'll have to just do without the lowest bass frequencies...ugh


Well I didnt loose much in the way of my touch screen. As its now my monitor for viewing videos and also still handles the A/C controls. The only thing I did loose and miss is the steering wheel controls. But Im trying to figure a way to get a pac module to work.


----------



## Dspencer (Sep 5, 2013)

HiloDB1 said:


> Well I didnt loose much in the way of my touch screen. As its now my monitor for viewing videos and also still handles the A/C controls. The only thing I did loose and miss is the steering wheel controls. But Im trying to figure a way to get a pac module to work.


I believe Axxess Metra has the equipment that will accomplish steering wheel control using aftermarket source unit for our vehicles. SonicElextronix sales them, might also check eBay, and of course verify via the Axxess website which unit/model/adapter numbers you need for the vehicle.


----------



## HiloDB1 (Feb 25, 2011)

Dspencer said:


> I believe Axxess Metra has the equipment that will accomplish steering wheel control using aftermarket source unit for our vehicles. SonicElextronix sales them, might also check eBay, and of course verify via the Axxess website which unit/model/adapter numbers you need for the vehicle.


There is no current option out there for my vehicle. I have checked all these manufacturers and none have one.


----------



## Dspencer (Sep 5, 2013)

Auto manufacturers could probably save money AND get rid of these types of problems just with a little bit of conventional wisdom...


----------

