Is it better to connect subwoofer to speakers or to the amplifier secondary output?

[iiv]

My old 80's amp has two different speaker outputs (but only two channels - the two outputs are identical). It doesn't have a sub output, so I will need to wire it up either using the unused speaker output or by adding more wires from the speakers' inputs. What would be better? Does it matter? Thanks!

 

[skinnypuppy71]

From the amplifier speaker terminals...if the sub is a rel, it should come with the companies neutrik cable....they much prefer the amplifier speaker outputs to the sub.

 

[iiv]

I think I might've not explained it properly: the amp doesn't have a sub out. It does however have two speaker outs (for A/B testing, I presume). My question is whether I should connect the sub to the A out (which my speakers use) or the B out which is currently unused.

 

[skinnypuppy71]

I'd use the output that the speakers are using, the subwoofer will then receive the exact same signal that the speakers are also receiving, I'm assuming you're using a active subwoofer, if you are using a passive sub then this route might not be suitable,

 

[jjbomber]

From the amplifier speaker terminals...if the sub is a rel, it should come with the companies neutrik cable....they much prefer the amplifier speaker outputs to the sub.

Nailed it in one.

 

[Gray]

I will need to wire it up either using the unused speaker output or by adding more wires from the speakers' inputs. What would be better? Does it matter?

You'd be effectively connecting to the same thing of course - so maybe go with whatever is convenient (closest to the sub).

The amp's unused speaker terminals probably involve additional switch contacts - so if you choose the amp end, do as skinnypuppy says and pair off from the currently used amp terminals.

 

[Gray]

if you are using a passive sub then this route might not be suitable,

If he was using a passive sub, wouldn't that be the only suitable route?

 

[twinkletoes]

You have to be careful not all amps like being connected at the speaker terminals. High level. It’s generally better this way but again not always possible with some amps.

To be on the save side I’d connect to preout’s ” low level” doubt you notice any difference in sound quality in all honesty

That’s a assuming it’s an active subwoofer

If passive you’ll need make sure the amp has the power to drive it.

 

[skinnypuppy71]

If he was using a passive sub, wouldn't that be the only suitable route?

I've never used a passive sub, so not certain of the connectivity route. Basically a disclaimer from myself.lol.

 

[roaduck]

My big Danley and BK Monolith + both support direct connection to an integrated amp`s speaker terminals - either bare wire or stacking banana plus to locking XLR neutrik on the back of the subs.

It depends if the sub has dual inputs - I`ve had my BK plugged into sub pre out of a micro system and 2 amp speaker terminals on my int amp simultaneously with no problems whatsoever.

 

[Vincent Kars]

for A/B testing, I presume

No. Most of the time you can choose A, B or A+B. B is supposed to be a second zone.
As it is a 2 channel amp, you have 1 amp per channel hence 1 speaker per amp (A or B) or 2 wired in parallel (A+B) to a single amp.
Check your amp as the specs often are 4 Ohm speaker impedance when using A only and 8 Ohm speaker impedance if using A+B. Simply because 2x 8 Ohm speakers in parallel yields a impedance of 4 Ohm and 2 x 4 Ohm a load of 2. 2 comes close to a short so your amp might not like it at all.

Wiring the sub to A or wiring the sub to B and set the amp to A+B won't make a difference electrically. You simply have your speakers and sub wired parallel.

 

[roaduck]

Subwoofers can have the normal unbalanced low-level RCA phono inputs and balanced high-level XLR neutrik inputs as well but the balanced (earthed) sockets are usually reserved for prosumer, high-end, PA and studio sub-bass hardware.

You can also get round the problem of no pre-sub out terminals on an integrated amp with hardwired in-line male-female phono plug/sockets with built-in resistors and/or trimmer pots.
I have also used simple mini passive preamps with high level inputs with good results in the past.
There are 3 distinct types of units but the most common are line output converters.

The uni/bidirectional hardwired phonos with built-in resistive attenuation are not that expensive either - about £20-£50 upwards.

Something like this would suffice

Audio Attenuators

These audiophile devices simply plug into any input sockets and reduce signal levels by 3dB, 6dB, 10dB, 12dB or 20dB.

www.decibelhifi.com.au

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Or one could utilise a passive pre-amp like this

Amazon.co.uk

Of course this solution is for an active sub.
If the OP only has a passive sub personally I would put the combined left and right output from the second set of speaker terminals into the LOC in parallel.

One can also utilise a subwoofer bass management preamp with mirrored and high-level inputs and DSP like an Antimode.I had the 8033 years ago and it was brilliant - it irons out the boomy peaks and boosts the troughs - all automatically.It is a lot simpler than the Behringer DCX2496 which is very versatile but requires a steep learning curve, patience and plenty of trial and error.I don`t need a sub management DSP unit these days.

PRODUCTS | DSPeaker

www.dspeaker.com

I have one of these that one can use in conjunction with RCA to XLR leads.

Behringer | Product | DCX2496

www.behringer.com

Another solution is an analogue or digital parametric equaliser with high level in or a DSP subwoofer bass preamp from a semi-pro/pro manufacturer.

 

[Gray]

Of course this solution is for an active sub.

I would think so ✅
No passive sub is ever connecting to my amp's speaker terminals, thanks very much.

 

[iiv]

No. Most of the time you can choose A, B or A+B. B is supposed to be a second zone.
As it is a 2 channel amp, you have 1 amp per channel hence 1 speaker per amp (A or B) or 2 wired in parallel (A+B) to a single amp.
Check your amp as the specs often are 4 Ohm speaker impedance when using A only and 8 Ohm speaker impedance if using A+B. Simply because 2x 8 Ohm speakers in parallel yields a impedance of 4 Ohm and 2 x 4 Ohm a load of 2. 2 comes close to a short so your amp might not like it at all.

Wiring the sub to A or wiring the sub to B and set the amp to A+B won't make a difference electrically. You simply have your speakers and sub wired parallel.

That's very useful knowledge, thank you.

As you have assumed, the subwoofer is active. Thanks for the advice everyone!