USX4085 AMP Problem ?

[jeepsrock 10+ year member]

I have a US Acoustics 4085 Amp in my Jeep, been working nicely for a long time.

Channel 1&2 are used for my front infinity components and 3&4 are bridged for a Kicker Sub. I noticed something the other day that didn't make much sense, hopefully someone can clarify. If i disconnect the RCA in cables for Ch3/4 the sub still works, as if the Front (Ch1&2) RCA in cables are providing signal for all the Channels ?

Is their a setting that i am missing or did the internal components just give up on me ?

Thanks,

Pete

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[jeepsrock 10+ year member]

No one knows if this is normal ? ?

 

[Shinju 10+ year member]

100% normal, Some multi channel amplifiers have the option to run just 1 input to run the whole amp for those who have a source unit with only 1 preamp out.

Alot of multi channel amplifiers now day's have a switch to run chan 3 and 4 from chan 1 and 2 input, alot of older amplifiers just did the switching inernal.

 

[jeepsrock 10+ year member]

So whats the point of connecting the Sub PreAmp outs then, i mean it doesn't seem to be making any audible difference ?

Is there of verifying if the internal switching mechanism does indeed exist in this amp or if its just a blown/bridged internal situation.

pete