Adding a 2nd Sub to a 2 Channel System

I run 2 JL E112 using their crossover between my preamp and amp. 

With that said one sub sounds terable compared to two. The room just does not balance out and my nodes were crazy. With two it sounds great. 

One of my subs was at the dealer for crossover repair (first run issue, fixed now...) and it sound so much worse than two I just stopped using it until the 2nd sub was fixed. 


 I doubt you will be able to tell the subs are running in mono. Honesty mono has some bennifits of eliminating room nodes. 

Depending on the positioning of the subs and on room acoustics it could very possibly help to smooth out and flatten the frequency response in the deep bass region, as perceived at the listening position.

However I suspect that you would run into an impedance problem. The input impedance of the E-110’s line-level input is only 10K, and if the PL’s mono line-level output is connected to two such subs it would be loaded by half that amount, or 5K. As a tube-based design the PL’s mono output is probably driven via a coupling capacitor, which I suspect would cause its output impedance to rise at deep bass frequencies to much too high a value in relation to 5K. The result being roll-off of the deep bass content of the signal that would be supplied to both subs.

Also, while the E-110 provides speaker-level inputs which could be used, I note that its manual states that those inputs are provided for convenience only, and are not the preferred connection method.

So before going any further I would suggest contacting PL or its distributor and asking if connecting a 5K load impedance to the mono output would be suitable.

Regards,
-- Al

Just as two heads are better than one so it goes with subs.

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Martin

Al,

Thanks for the technical aspect of adding a 2nd sub. I didn't think of a possible impedance issue so I'll contact PL as suggested. 

Thanks, Ron

Additional subs will excite modes and contribute to a fuller sound and flatter response. A left and right signal will further benefit sound quality and lushness in these respects and in higher frequency bands depending on layout and recording.

I dont see high level speaker inputs on the back of that fathem. If it lacks them you can get speaker line to RCA adapters and wire a left and right. I have done that before. Although Im not familiar with that particular amp so you might want to double check specifically. Some amplifiers need to be grounded. Its safe with some while with some others its not. I recall encountering the hazard note that applied to hooking a sub to a particular tube amplifier while using speaker line outs. Although it might not apply with the adapter connection aforementioned. A neutrik was being utilized in the other situation.

Measurements would answer this question.

While, in theory, a second sub, assymetrically placed, would help, the benefit could be very small.

Bass Traps, and sub EQ (if not already there) are the first things to add. Then, if measurements suggest you still have important room modes to treat, a second sub.

Best,


Erik

Two subs will sound substantially better than one because you won't be able to localize where the bass is coming from.

@limniscate You can't localize a single sub either, when "properly integrated". I defy anyone to hear either my main speakers or my sub as distinct  sound sources. :)

Again, it's all about configuration, and configuring a sub is a major PITA. :)

Best,


Erik