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Question Wiring up subwoofer to speaker terminals (stereo setup)

Crazeenick

Active Member
I am running a 2-channel stereo system with an Arcam A85 integrated amp paired with an Arcam P85 power amp, driving a pair of B&W CM10 S2 main speakers. I have the Arcam units set up in a bi-amping configuration with the A85 driving the HF/Mids and the P85 driving the LF on the speakers.

I have recently bought a B&W ASW10CM subwoofer to compliment the main speakers and give a little extra bass oomph. The Arcam amps do not have subwoofer or LFE outputs, so I will be connecting the subwoofer using its high-level (speaker) terminals.

I want the main B&W speakers to still see the whole frequency range from the amps. I also want the subwoofer to see the full frequency range, but will use the subwoofer crossover frequency control to select the lower frequencies I want from the subwoofer (eg below 70Hz).

Can someone please advise me whether the following wiring method would work OK?

Wire the two amps to the main B&W speakers as before (A85 to HF/Mid terminals and P85 to LF terminals). Then run a secondary pair of speaker wires from the LF terminals on the main speakers into the subwoofer high-level (speaker) terminals.

Q1. Does hooking up the subwoofer to the LF terminals on the main speakers diminish the LF signal the main speakers see (cf the HF/Mid signal?).

Q2. Would connecting the subwoofer to the HF/Mid terminals on the main speakers give exactly the same result as connecting to the LF terminals?

Q3. What about running the wires from the amps direct to the subwoofer and then secondary cables from the subwoofer to the main stereo speakers? Would that too be the same?

Please advise which would work best!

Thanks!
 

MI55ION

Distinguished Member
Q1: no
Q2: yes
Q3: yes in theory but avoid*

*apply the "kiss" principle, keep them short and follow the path of least resistance to avoid signal degradation.

Option 4 is to use the line level preouts from one of the amps into the line in of the sub. As with using speaker level inputs the sub will do the bass management so you dont need dedicated lfe preouts.
 

RadioRentals

Standard Member
So as not to duplicate pretty much the same question, I hope the OP will forgive me for piggybacking his query.

I have a Jamo 200 which I am connecting to an Aiwa AX7600 tuner/amp of 1980 vintage.
It will be used exclusively for music. The front speaker is a Radio Rentals bakelite case of the 1940s with a more modern driver, which one I cannot recall.

The Jamo 'manual' consists of a few Janet & John pictures and no text nor explanation whatever.

The sub has the options of speaker connections or line in. The amp has no dedicated LFE output, and the only line-out available is Tape 2 as all the others are occupied.
Tape 2 has a Record output of 150mV/<50 kohms.

Will this drive the sub without imperilling the amp? The sub is 22 ohm.

Or should I use the speaker connections? In which case will the cutoff controls on the sub still operate?

What are the relative merits of line in, or speaker connection?

Sorry if this is all rather basic.

Thanking you in anticipation.
 

noiseboy72

Distinguished Member
Do not use line outputs, as these will not be controlled by the the volume control. @Mi550N is talking about using the pre-out sockets, which your system does not have.

The sub does not have an input impedance of 22 Ohms, it will be more like 22KOhms and will not affect the output from the amplifier at all. It does not consume any power, just uses the voltage level.

The sub controls still work in the same way. The speaker input is reduced down to line level inside the sub and then fed into the same circuit as the LFE socket.
 

MI55ION

Distinguished Member
Do not use line outputs, as these will not be controlled by the the volume control. @Mi550N is talking about using the pre-out sockets, which your system does not have.

Hmm, I see where you're coming from. To clarify as the fourth option I was suggesting A85 preouts to P85 as it is connected now. Then using the P85's pass-through line output (normally reserved for looping the signal e.g. tri-amping) into the line inputs of the sub. The A85 should control the master volume in this configuration, the P85 as slave simply passing the signal through. I could be mistaken as its known to have happened once :D but confident it should work in the OPs system.

Of course the high level (speaker) options are still available if required.
 

RadioRentals

Standard Member
And thankyou from me.

After considerable distractions, I fired up the Jamo 200 today.

Connected to the speaker terminals, as suggested. Because I only have one front speaker, a Radio Rentals model 91, for connoisseurs of that brand, I looped the + and -, so it's working in mono.
The cutoff control does indeed still work.

The sub is sited under a small staircase, in a corner of the room. When I say 'the room'; this is not actually the same room as the front speaker. That is in the dining room, at the top of the staircase, the sub is in the sitting room at the bottom of the stairs some two feet away as the crow flies or would if it were unfortunate enough to finds itself in our C17 cottage.
Under the staircase is perhaps not ideal, but it's there or not at all.
It does encourage boominess, OK with R3, not so great with anything more bass-heavy. I'll do some tinkering this evening with the level, the cutoff, and the cutoff and bass controls on the amp.

But, it's working. I bought the sub four years ago, and it's been sitting in a box awaiting the moment when I would next take the staircase out so I could fit the sub in place - it won't fit unless I remove the staircase first - and this happened because I had to do some plastering.
Wouldn't it be boring if everything were simple.

Anyway, thankyou chaps.
 

Ianfromnotts

Well-known Member
I have always found sub bass to be more directional than one might expect and best results when the subs are near the speakers, what I cant get my head round is why is why the usual approach for high level inputs is from the speaker outputs on the amps rather than the speakers themselves?

sell longer cable maybe?

or is there a scientific benefit to connecting to the amp terminals rather than the speaker terminals?
 

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