Old Stereo Receiver w/ subwoofer?

2003-07-24 20:38:08

I have a Harmon Kardon stereo receiver HK 630i or 670i I think (with A/B speaker outputs) from about 10-12 years ago. There is no sub out. I have a pair of 23 year old Luxman speakers (2-way) that I'd like to keep. I have a new Klipsch subwoofer that doesn't have outputs for the speakers, only inputs. My question is how do I hook-up the sub to this receiver. Do I put the Luxmans on the A channel and the sub on the B and run both? Or do I route the Luxmans and the sub all off one channel?

Sorry if this has been discussed, I searched this forum for answers and couldn't find anything. I got two different answers from the two decent audio stores in town (the two options I described above) and each person said that the other option was not good. Confusing, eh?

Thanks for any help you can provide.

synchros

Old Stereo Receiver w/ subwoofer?

Reply #1 – 2003-07-24 21:37:30

Well, the funny thing is that most stereo receivers that have A/B speaker outputs just connect the speakers in parallel when you select A+B, so the two options you describe are really exactly the same thing. And without buying anything else it is really your only option.

The only problem with it is that the bass frequencies will still be going to the Luxmans, and I imagine that they're not too big or you wouldn't have bought a subwoofer. I suspect that there must be some sort of external crossover for this situation that you could use, but I haven't seen one. Alternatively, you could just put a capacitor in series with the Luxmans to provide a cutoff for the bass.

Old Stereo Receiver w/ subwoofer?

Reply #2 – 2003-07-24 23:09:56

Thanks for your response. I was thinking about whether an external crossover was something that existed. I assume that something like that is what is in these subs that "pass-through" the signal to speakers via L and R speakers out connectors.

And you are right, the reason I'm adding the sub is that the Luxmans are fairly small.

Thanks again for your help.

synchros

Old Stereo Receiver w/ subwoofer?

Reply #3 – 2003-07-24 23:43:49

External crossovers that turn speaker lines into RCA pre-outs do exist - I use one for the subwoofers in my car  . Go to a place such as Myer Emco or Circuit City - I'm sure they will have a part for either car / home audio that allows you to do what you want. Just hook the converter to the B channel. Enjoy!

PS - IIRC, the part I bought cost around $10 to $15, so this should not cost lots of money  .

Old Stereo Receiver w/ subwoofer?

Reply #4 – 2003-07-25 00:01:56

I found this at Parts Express, but am not sure if it is right.

http://tinyurl.com/hz3h

Lots of crossovers/kits there.

Converting the speaker-out to RCA pre-outs in just changing the connector, right? I can wire the speaker-out into the sub, there are connectors on the sub for the speaker wire inputs. What I'd like to do is filter out the sub frequencies before sending the signal to my bookshelfs.

Thanks,

synchros

Old Stereo Receiver w/ subwoofer?

Reply #5 – 2003-07-25 00:54:19

You'd need a crossover & another amp if the sub is not self powered.

Is the sub self-powered?

If so then DO NOT connect speaker level out to the line-in (RCA) on the sub, it will ruin it.

If the sub is not powered then you will need a separate amplifier for it.

For crossover it may be wise to get an M-Audio Revo card (has bass management) if you use the system for PC-only listening.

Old Stereo Receiver w/ subwoofer?

Reply #6 – 2003-07-25 01:13:59

Some subwoofers, like mine (Mirage FRX-S8), have what are called "High Level Inputs".  These are very simple, you simply connect two speaker wires together on one end (minding the positives and negatives) and hook the connected end up to the High Level Input on the Sub and the two single ends into the Amp and the main speakers.  This reduces sound quality a little but it eliminates the need for a modern amp.

Old Stereo Receiver w/ subwoofer?

Reply #7 – 2003-07-25 02:16:09

I don't suppose your reciever has jumpers for pre-out/amp-in?  If so, then you wuld
put a line-level crossover there and the amp-in gets your main (highpassed) signal
from the crossover.

You could also do this at the tape loop, except then the volume control would only
work on the high side (unless you have a 4 channel reciever like my old technics)

Old Stereo Receiver w/ subwoofer?

Reply #8 – 2003-07-27 01:00:40

Which Klipsch sub in particular are you referring to here?

Old Stereo Receiver w/ subwoofer?

Reply #9 – 2003-07-29 03:20:44

Sorry was away for a long weekend.

The sub is powered, a KSW-10. It does have the RCA in, in addition to an input for regular speaker wire. I'm using the latter with the B channel, the A channel goes to the R and L speakers. And, no, the HK doesn't have pre-out.

I guess since it is working (at least it sounds like it is...) with the A/B my only issues are that the small speakers are still trying to output the low frequencies when they don't need to, and I've lost the ability to use the receiver to run a second set of remote speakers on the B channel that the sub is now using.

BTW, thanks for all the good info, this is a very helpful crowd!