[tubegroove]

Has anyone connected an active powered subwoofer in parallel to a RM10 - the way I am thinking about it is to connect the amp to the speakers and again the speakers to the speaker level input of the sub?  is this a safe and effective way to hook up a sub?  I use a passive pre and as far as I know I cannot connect a line level output to a sub
Would appreciate any input on this, thanks

[Roger A. Modjeski]

Has anyone connected an active powered subwoofer in parallel to a RM10 - the way I am thinking about it is to connect the amp to the speakers and again the speakers to the speaker level input of the sub?  is this a safe and effective way to hook up a sub?  I use a passive pre and as far as I know I cannot connect a line level output to a sub
Would appreciate any input on this, thanks

Unless you listen at low power levels, it is always best to take the sub signal off the preamp and put a small capacitor in series with the input of the main amp so that it is not duplicating the sub signal. This takes load away from the amp and speaker. What kind of passive do you have? What is its output impedance?

[tubegroove]

I do listen at low levels (but sometimes turn it up).  I connected the sub over the weekend to my speakers. Makes only a marginal improvement and not certain but it may even be interfering with the mid range decay.  Perhaps I havent dialed it in well enough-its my first time
I use a transformer coupled passive from a company called Music First Audio.  Has only one set of RCA outputs.  Don't know the output impedance (no specs provided).  What I have been told is that it can drive an power amp >=5k ohms input impedance.

[Roger A. Modjeski]

I do listen at low levels (but sometimes turn it up).  I connected the sub over the weekend to my speakers. Makes only a marginal improvement and not certain but it may even be interfering with the mid range decay.  Perhaps I havent dialed it in well enough-its my first time
I use a transformer coupled passive from a company called Music First Audio.  Has only one set of RCA outputs.  Don't know the output impedance (no specs provided).  What I have been told is that it can drive an power amp >=5k ohms input impedance.

Given the low output impedance you can put a Y connector on the output and drive the woofer through it's RCA jacks.

In an ideal system, you would have an electronic crossover after the preamp which would then split the signal at the crossover point sending the divided signal to the appropriate amps.

[tubegroove]

Yes, I guess I could drive the sub from the pre using a Y connector.  As I listen (mostly jazz), I seem to like my setup without the sub!  It sounds more natural, although not as extended in the low registers as with the sub, but not greatly lacking either.  Need to convince myself that I really need a sub  and then can get into all the $$ and work required for an external crossover, integration etc

[Roger A. Modjeski]

I can make a simple 6 dB/octave crossover for a sub with a line level input. It has several advantages over a Y connector for passive preamps or preamps that do not like much load. One of the problems with a Y connector (or a second pair of output jacks) is that the long run to the sub needs to have a low total capacitance. With the crossover I make there are no highs on the sub cable so its length or capacitance is no longer an issue.

A further advantage of this passive crossover is that it filters the signal to the main amp via a single capacitor. To do this properly the input impedance of the main amp and crossover input must be known. I have made these in die cast metal boxes with the same custom gold RCA jacks I use on all my amps. These typically cost $175. Other than a steep active crossover this is the best way to go.

[tubegroove]

Roger, good to know you can do a passive x-over should I decide to go the sub route. However, as I am playing around with a borrowed sub to figure out if I like the sound with a sub, how much of a compromise (or risk) is it to drive the sub from the main speakers using the speaker level inputs?