stereo pre amp to sub question

[staf]

hi folks

i am setting up my subwoofer which im connecting via the pre outs of my pre amp but, at the moment only using one side of the stereo pre amp as ive only got one interconnect until i get paid, so im wondering what the difference in sound levels would be when i connect both left and right from the pre amp?

is it 3db? or something else?

thanks heaps!

 

[whoaru99]

It depends, probably, on the content of the signal and, probably, how the subwoofer summing function works. In theory, I believe feeding two signals with same content into the summing network would result in 6dB increase.

In an experiment of mine, feeding the same mono signal to both inputs of one of my subs increased the sub's volume by 4.5dB. That does not, however, mean the sub is 4.5dB more powerful, it just means the net gain increased by 4.5dB. To rebalance the level, I had to turn down the adjustment on the sub.

Right now, the bigger thing IMO than a net gain change is that you are missing the content of one channel that is not common with the other channel.

 

[onplane]

hi folks

i am setting up my subwoofer which im connecting via the pre outs of my pre amp but, at the moment only using one side of the stereo pre amp as ive only got one interconnect until i get paid, so im wondering what the difference in sound levels would be when i connect both left and right from the pre amp?

is it 3db? or something else?

thanks heaps!

Staf, doesn't your sub have a volume control? If so there should be no difference in sound EXCEPT for (what whoaru99 mentioned) your lack of bass from the missing channel.

That is, supposing you are listen to a jazz trio with the double bass on the right. If you only connect the left channel to the sub, you'll miss the lion's share of the bass.

Another alternative is that some subs allow for speaker level inputs. Staf, does yours?

Regards,
Jerry

 

[staf]

thanks heaps for your thoughts!

onplane, yes my sub does have both vol and speaker inputs

i was just curious

ill buy another cable tomorrow

 

[onplane]

thanks heaps for your thoughts!

onplane, yes my sub does have both vol and speaker inputs

i was just curious

ill buy another cable tomorrow

Staf, there is well respected sub manufacturer who strongly recommends speaker level inputs for 2 channel music systems. Reasoning behind this is they want their subs to "see" exactly the same audio signal that the main speakers see with all of the phase shifts introduced in the power amp. They claim that connecting this way makes integration in music systems much, much easier.

Regards,
Jerry

 

[staf]

hmmm interesting Jerry

my power amp only has 1 set of speaker outs, would i be able to get a common splitter to double up? or just wire it up with the main speaker output ?

cheers

 

[the skipper]

my power amp only has 1 set of speaker outs, would i be able to get a common splitter to double up? or just wire it up with the main speaker output ?

If you have a powered sub then you'll be fine.

With a powered sub, you're feeding into a very high impedance amp, not a low impedance speaker, so the sub is invisible to the power amp. It doesn't even know it's there.

 

[onplane]

hmmm interesting Jerry

my power amp only has 1 set of speaker outs, would i be able to get a common splitter to double up? or just wire it up with the main speaker output ?

cheers

Staf, you can just wire the sub up to the main speaker output on your amp or if the sub is closer to your main speakers, you can get the signal from them as well.

Many modern speakers have terminals for bi-amping. Staf, if yours has these, you can take the audio signal from the "unused" terminals on your speakers.

As Skipper said, no significant current will flow in the lines to the sub, so you can use the cheapest wire you can find at Home Depot.

Regards,
Jerry

 

[staf]

wow, good to know Jerry!