Can I fit a subwoofer to a regular amp?

Paddy O Dawes

Standard Member
Can I fit a subwoofer to a standard type amp, with only standard L&R speaker connectors? I was told I could connect a subwoofer to any of the line out sockets (tho' I'd have to make any volume adjustments on the subwoofer itself).

Assuming that's right, is the line out you can see here (on the bottom) the right one to use?

f3uirc.jpg


(It's an old Harmon Kardon system, with all the components brought together and feeding into the one 'Main in' pair you can see next to it.)

I'm guessing I'd need an active subwoofer.

Thanks for any advice.
 

Berties

Banned
Yes and no. Yes you can connect a subwoofer with RCA cables, but line level is fixed so whenever you adjust the HK amp, the sub volume will stay the same which is pretty stupid unless you never change the volume on the amp. You'll have to use high level (speaker cable) outputs/inputs instead, so from stereo speaker binding posts to a subwoofer with speaker level inputs. That way as you adjust volume the sub changes volume relative to the speakers.

Unless your amp has pre-outs, then you'll need to use high level.
 

Paddy O Dawes

Standard Member
Thanks for responding.

The guy in the shop did say that I'd need to adjust the volume on the subwoofer unit...apart from that, he was right and it is possible, if I understand you right. That wouldn't be a major problem, in truth - this is for a kitchen, and I really only need three volumes: low (dinner), medium (cooking), high (party).

Or, if I understand you right, I could connect the speaker terminals on the amp to the subwoofer, then the regular speakers to outputs on the subwoofer, then the whole lot would respond to changing volumes on the system?
 

Berties

Banned
Correct on both but why would you choose the first? Pain adjusting subwoofer everytime you adjust the amp. Do it right the first time.

You could do the latter, some subwoofers offer high pass crossover, so for example if you're sending full range from a integrated amp to tiny satellites, it'll be too much bass for them to handle. So by going amp---->sub--->speakers the sub will pass the high frequency out onto the speakers.

Usually only better subs have this though. I think I'm doing that with the SBS SB12+ but not at speaker level but at line level so

preamp pre-outs----->sub---->poweramps----->speakers
 

Paddy O Dawes

Standard Member
Thanks again Berties. I think the basic reason to go that route is that my system is too basic to allow the more sophisticated one. It's an all-in-one Harmon Kardon system (Festival 300), and the connections are pretty basic. I don't think it has a pre-amp/poweramp. As in the pic, there's just the one 'Main in', which takes the feed from the CD/tuner/tape inputs combined, with the Line out next to it.

I'm off to bed now - just in case you respond and I don't - but thanks again for your help.
 

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