Subwoofer connections

[seadzz]

I have no choice but to use the Spker level connections and due to room size, main speaker location and amp location running the first set of wires to the subwoffer and then branching out to the main speakers is trouble for me.

I have connected my main speakers to the amp in the normal way and piggybacked the LH and RH supply to my sub off of the same binding posts as my main speakers. I know the manual says to feed the sub first and branch off to the mains speakers.

Will I do harm to anything by connecting the subs and the main speakers of the same binding posts? I suspect I would lose the crossover bandpass function on the sub but this is not a real issue.

I have attached a rough drawing of my connection since my wording may lead to some confusion.

Many thanks and I did search your forum for an answer to this question prior to posting.

sdz

[travisc]

bump

[formica]

I wish I had a definite answer... but I can only go on

assumptions.

Connecting a second set of wires to the same speaker posts

will put the subwoofer and main speakers in parallel. You are

concerned with the net resistance this produces at your

amp (actually impedance, but I'll not complicate more than it needs

be). We know that Speakers with resistance R1 connected in

parallel to a

subwoofer with resistance R2 will give you 1/(1/R1 + 1/R2).

I don't know what resistance the subwoofer presents to the

speaker terminals in the first place, but I'm guessing that it is pretty high.

I'm basing this on the fact that V=IR and given a fixed voltage... a high

resistance will produce a low current.

This makes logical sense as it only need to read the signal from the speaker wires and not

power itself.

Now going back to the 1/(1/R1 + 1/R2) we see that the larger

the R2 the less it'll effect the net resistance. For example, we have a set of speakers with 8ohms resistance and

to these we add a subwoofer with a resistance of:

8ohms gives a net resistance of 4.00 ohm

64ohms gives a net resistance of 7.11 ohms

512ohms gives a net resistance of 7.87 ohms

4kohms gives a net resistance of 7.98 ohms

After typing that I did find a link to a competitors

subwoofer page who desribe the following...

If your amplifier only has one set of outputs you may connect

your amplifier to your speakers as normal and run an additional set of cables

from your speakers to the Dynamos left and right speaker level (high level)

inputs. It is also possible to connect the left and right outputs of your

amplifier to the left and right speaker level (high level) inputs of the Dynamo

and run an additional set of cables from your Dynamo to the speakers.

In both cases I think you should be safe... []

Rob

[efzauner]

It all depends. If the sub has a high pass connection, by running the speaker cables first to the sub, and then to the mains, the sub will reproduce the lows, and the mains will reproduce the highs (the high frequencies will "pass" to the mains, thus

"high pass"). If you have small speakers (say a 5 inch woofer or less) then this is the way to go. If you have larger, full frequency response mains, then you want to run the mains in parallel with the sub, just as you connected. Another dumb question: is your sub an amplified sub (does it plug into the wall)? if yes then it has high impedance (resistance) inputs and it does not add any extra load to your amp. If it is a passive sub, then it will add load to your amp and Formica (hi, hows it going?) has the right numbers.

Hope this helps.

[Speedball]

I have had mine hooked up the very same way......sub and speaks on the same binding posts and it worked fine.

...........................................[A]