Did I get a bad subwoofer?

[rover]

I posted a few days ago about connecting a vintage late 70s integrated amp to a subwoofer. I have to use a speaker line connection as the amp has no sub out.

I tried to connect today. Speaker wire from amp to sub and then from sub to speakers.

The result: Nothing. Except for faint base from sub. No sound from speakers and next to nothing from sub. When I turned the amp on in this setup, you can't even hear the power click that it normally happens.

Any ideas? Am i doing something wrong? Is the sub defective? Or as a guy that works on fixing older stereo equipment told me a few months ago-you can't connect your old vintage amp to a subwoofer? It won't work.

[Mr Peabody]

There shouldn't be any reason you can't hook a sub up to your amp using the speaker terminals. It does sound like something is wrong with the connection. How exactly did you hook everything up? If your amp has two sets of speaker terminals, like most vintage amps do, I'd hook the speakers to "A" and the sub to "B" terminals. Try just hooking the sub up by itself to see if it plays louder or allows you to adjust it. You'll have to play around to see which piece is causing your issue. What amp do you have?

[blackraven]

Try running the sub directly off the speaker outs of your amp.

[rover]

There shouldn't be any reason you can't hook a sub up to your amp using the speaker terminals. It does sound like something is wrong with the connection. How exactly did you hook everything up? If your amp has two sets of speaker terminals, like most vintage amps do, I'd hook the speakers to "A" and the sub to "B" terminals. Try just hooking the sub up by itself to see if it plays louder or allows you to adjust it. You'll have to play around to see which piece is causing your issue. What amp do you have?

I have an old Sanyo amp rated at 45 watts per channel. It was hooked up with wire from amp to sub in and wire from sub out to speakers. I've got floor standing speakers hooked up to "A" and bookshelf speakers to "B". I could unhook the bookshelves and connect amp to "B" to see if that works. I don't usually use "B" speakers when listening to music. Mainly have on with "A" during movies. It takes too much punch away from the "A" floor speakers for music, IMO.

One thing I had to do was splice some 18 gauge speaker wire to the 10 gauge wire that ran from amp( "A" ) to the sub in. the 10 gauge was too short to reach amp other wise. I also used the 18 gauge from sub out to speakers. I have some 14 gauge coming, so I'll try that when it gets here.

I'll try just hooking amp to sub to see what happens. I'll try fiddling around with the settings again, but everything was absolutely dead with only the slightest base coming from sub.

[rover]

I got the sub working. Splicing the wire from the amp to sub in was probably not a good idea. Also, I found out that one section of speaker wire was defective.

So it seems to be working, although a little boomy right now. The sub is a Polk Audio PSW-110. I'll see how it sounds after playing it for awhile. And getting it all connected with the 14 gauge wire.

Any advice on settings? Volume, low pass, phase? My main front floor standing speakers are KLHs at 10-250 watts@8 ohms, 12" woofer, frequency response is 28-20,000Hz.

[Mr Peabody]

If the KLH really approached 28Hz you wouldn't need a sub, I doubt if the sub even goes that low. I would start with a sub setting about 50Hz and then dial the volume/gain until it blends with the KLH as best you can get it. Once it's blended you can try raising the frequency on the sub to see if you like it better at a higher point. You may have to play with the sub's position to see where it works best. Many manufacturers claim the sub works better in a corner but if that causes more boom try moving it out from there in small increments.

[blackraven]

One mistake that many people make when they get a sub is to play the bass too loud. The sub should disappear into the sound and should only be heard on bass heavy music but it should be seamless. If the sound has boom to it then the sub is set too high and you may have the crossover too high. I have a Martin Logan sub with my Magnepan 1.6's which go down to 40Hz and maybe a tad lower due to room placement. I have my sub set at 35 to 38Hz. I only notice the improved bass on bass heavy music, otherwise you don't notice the sub.

By the way, what is the frequency response of your main speakers?

A good way to set the sub is to keep turning down the volume of the sub till you do not or barely notice it and then turn it down a smidgen more.

I hope this helps

[rover]

One mistake that many people make when they get a sub is to play the bass too loud. The sub should disappear into the sound and should only be heard on bass heavy music but it should be seamless. If the sound has boom to it then the sub is set too high and you may have the crossover too high. I have a Martin Logan sub with my Magnepan 1.6's which go down to 40Hz and maybe a tad lower due to room placement. I have my sub set at 35 to 38Hz. I only notice the improved bass on bass heavy music, otherwise you don't notice the sub.

By the way, what is the frequency response of your main speakers?

A good way to set the sub is to keep turning down the volume of the sub till you do not or barely notice it and then turn it down a smidgen more.

I hope this helps

Thanks for the info. The frequency response of my main speakers is 28-20,000 Hz.

[rover]

If the KLH really approached 28Hz you wouldn't need a sub, I doubt if the sub even goes that low. I would start with a sub setting about 50Hz and then dial the volume/gain until it blends with the KLH as best you can get it. Once it's blended you can try raising the frequency on the sub to see if you like it better at a higher point. You may have to play with the sub's position to see where it works best. Many manufacturers claim the sub works better in a corner but if that causes more boom try moving it out from there in small increments.

That's a good point. The main speakers have a 28-20,000Hz freq. response. The sub is rated at 32-250Hz freq. response. But the Low Pass is adjustable from 60Hz to 160 Hz. Right now, I have the Low Pass set to lowest(60Hz).

Does that seem right? Maybe a sub isn't going to add much. I'll try listening for awhile more to see. And moving the sub around once I get more speaker wire.