Bass amp input impedance/voltage?

[bobby1781]

Hope everyone is enjoying themselves over the holidays.

Weird question, but I know someone in here knows the answer.

This started as just curiosity, but I have decent stereo speakers with adequate low end extension for music. I got to thinking, while I no longer own a sub if it would be possible to use my bass amp for some added low end. Thought it might even add a nice amount of detail to movie effects as it should be a much clearer/transparent sounding driver than just a sub-100hz rumble.

So, from my receivers sub woofer out, I plugged in an RCA-1/4 female adapter and then plugged the TS cable from there to the amp input.

Well, there is output, but it is extremely low (output not frequency) It is receiving a signal, turning the pre/post gains to the max it creates a tiny bit of a kick drum thump but obviously I wont run the amp like that.

So... is what I am trying even possible? I got the idea when reading through a fEarful thread awhile back where someone mentioned they used it for their home theater. Perhaps they also had a different amp for the cab.

I checked the voltage output of my bass guitar vs the subout and it seems that there should be plenty of voltage. Is this being caused by an extreme difference in impedance? I wasn't able to find the impedance of the output section on my receiver.

This morning I was thinking that perhaps the sub out is crossed over around 120hz internally and that the amp might actually have a subsonic filter creating a very narrow range. When I get home tonight I am going to try and use the center channel out and run it full range just to see if there is a difference.

I know this is a bazaar question and purpose, but for the sake of this little experiment I would love to know if its possible and if not why.

FYI: the adapter is a Mono RCA Male to Mono 1/4" Female
the 1/4" cable is a mono TS cable

[chucko58]

Your receiver's subwoofer out should drive any bass amp to full power. Consumer hi-fi gear typically cranks out 0.3-1V RMS on line outs, most bass amps should have a max sensitivity in the millivolts.

How high did you have the volume on the receiver?

[bobby1781]

That's what I found when looking into the voltage.

The receiver wasn't cranked by any means, but definitely loud enough there should have been considerably more bass.

I even adjusted the individual levels on the receiver raising the sub out +10db, each click up...+1, +2 actually created a loud low pop from the amp, similar to the sound if you ever tested a speaker using a battery. at +10db on the receiver and the gains up it was clearly getting the signal, but as you would imagine a very muddy over EQ'd sound.

[Darylt]

I'll tell ya what is possible - when I was a teenage Frankenstein I'd have the odd house party. I would plug a little shelf stereo type thing through my amp at the time, which was nothing massive, and it was insanely loud - had to tweak the eq and fiddle with the gain but worked for sure - enough that neighbors down the street could hear ... ahhh memories ...

[billfitzmaurice]

Originally Posted by bobby1781

I got to thinking, while I no longer own a sub if it would be possible to use my bass amp for some added low end.

It won't work very well, because the response of the average electric bass speaker goes no lower than that of the average hi-fi main. Even a middle of the road h-fi sub goes an octave lower than a bass cab, while a good HT sub goes two octaves lower.