# balanced input and input sensitivity for replacing factory amp



## crvz (Aug 11, 2013)

Apologies if this is redundant, I'm sure it is, but I want to make sure I understand this properly. This is more specific application than general concepts. I've got a 2013 135i on order, and I'm exploring aftermarket audio components (I've worked in the car audio industry in the past, and I've always swapped stuff out on my cars). I'm looking at getting one of technic's harnesses to replace the factory amp, and I'm researching amplifiers. Trick is, I've got a number of amps at the house that I would prefer to use. More recently, I've got two alpine amps in my truck which I will remove when the new car shows up. They are the MRX-F30 and MRX-M100.

Both of these amps have an RCA level input sensitivity of 0.2-4.0V. I don't think I can use that. 

However they also both have a speaker level input from 0.5-10V. 

What is the voltage of the balanced input coming from the OEM head unit (I'm assuming it's over the 4V my amps can handle), and can I just convert the RCAs coming off the technic harness to plug into my speaker level input of the amp?


- chris


----------



## Technic (Jun 24, 2002)

OEM HU balanced outputs are _low_ level, they are not _speaker/high_ level. Meaning, you will be attenuating an already low level signal if you use the high level inputs.

Regardless, those MRX amps do not accept balanced inputs via their low level inputs -I tried it, did not work.

You can get a cheap Audiocontrol Matrix line driver/_balanced to unbalanced converter _on eBay and then you can connect any amp to it...



crvz said:


> Apologies if this is redundant, I'm sure it is, but I want to make sure I understand this properly. This is more specific application than general concepts. I've got a 2013 135i on order, and I'm exploring aftermarket audio components (I've worked in the car audio industry in the past, and I've always swapped stuff out on my cars). I'm looking at getting one of technic's harnesses to replace the factory amp, and I'm researching amplifiers. Trick is, I've got a number of amps at the house that I would prefer to use. More recently, I've got two alpine amps in my truck which I will remove when the new car shows up. They are the MRX-F30 and MRX-M100.
> 
> Both of these amps have an RCA level input sensitivity of 0.2-4.0V. I don't think I can use that.
> 
> ...


----------



## crvz (Aug 11, 2013)

Technic said:


> OEM HU balanced outputs are _low_ level, they are not _speaker/high_ level. Meaning, you will be attenuating an already low level signal if you use the high level inputs.
> 
> Regardless, those MRX amps do not accept balanced inputs via their low level inputs -I tried it, did not work.
> 
> You can get a cheap Audiocontrol Matrix line driver/_balanced to unbalanced converter _on eBay and then you can connect any amp to it...


thank you, sir. check your PM regarding prior harness discussions.


----------

