My SVS story - never underestimate human stupidity... (1 Viewer)

[Dave Jewett]

Hello all,
I'm a short time lurker here (about 2 months or so), but I've finally achieved what I started out to do four months ago... build an awesome HT! The last piece of the puzzle arrived this afternoon, my SVS 25-31PCi. Trembling with anticipation, I unboxed it and set it up. Try as I might though, I just couldn't seem to get much bass out of it! I checked and double-checked the connections, reversed the polarity on the sub, and tweaked the levels up a bit. Nothing worked. It sounded good, but not exceptional.
I gave up for a while, figuring that my room must be to blame (3000+ cu. ft.), or something must be wrong in the sub placement. After all the hype, I was definitely disappointed. So I'm walking back to the kitchen about an hour ago, and I have one of those Homer Simpson-esque moments...
"You idiot! You didn't check the polarity on the sub cable!"
DOH! Sure enough, I got the dang thing reversed! So I fixed it, and it's taken every shred of will I have to tear myself away... this thing is AMAZING! I wish it wasn't 1am, or I'd crank it up and see what this thing can REALLY do! Man, I can't wait for tomorrow!
Cheers,
Dave

 

[steve nn]

Dave I here you. Sounds like you will have a exciting Saturday. My wife used to un-hook my sub cables because they ran across entrance to the HT living room. I would plug in a DVD and then say, "OK what's wrong with my sub". A few times I turned on the midnight function and forgot to turn it off, which would cause me to wander OK where is the oomph in my sub the next time I viewed something. Con-grads on your new purchase. Be sure to let Huston know that your cooking.

 

[Brian Kleinke]

Dave,
Welcome to HTF!! And welcome to the ranks of the Proud SVS owners... You'll have to tell us more after you really fire that baby up!
Brian

 

[JoelM]

Sounds similar to my story. I had 2 SVS25-31CS+'s hooked up and I was hereing absolutely nothing. Then I realized I had to get the Denon2802 on screen menu to work in order to turn on the sub. Finally after a couple of...shall I say...disappointing hours I finally got the menu up. Then I crossed my fingers and fired one of them up I literally jumped into the air. After I amped up the second I was absolutely shocked. I never knew how much deep extension I was missing. I waiting for my girlfriend to get home, and her reaction was similar to mine. Oh how I love SVS stories.

 

[David_D]

OK - I don't mind being stupid.... What do you mean when you talk about the polarity of the sub cable?

 

[Kimmo Jaskari]

He got the two poles of the cable crossed compared to the rest of the system. When his other speakers were outputting a bass sound, the sub would have been outputting the reverse of that, causing a cancellation rather than addition... needless to say, that would not make for very SVS-like sound to the system.
That's why it's important to make sure every speaker in the system is wired correctly to the amp.

 

[jeff peterson]

So he was using the speaker level inputs versus the low level input? When I hear the word "cable" I think of an interconnect rather than speaker wire.

 

[Dan Hine]

I was thinking interconnect too, which caused me confusion. I just didn't want to ask (thanks David). Especially since it's a PCi sub and not one of the CS series.
So Dave, for those of us that are curious, are you using the speaker level inputs or the line level sub output? If the later, could you explain what you mean by the polarity of them?
Regards,
Dan Hine

 

[Dave Jewett]

Hello all,
I am using the line level output of the sub. But the cable I bought (25ft. AR sub cable) has a specific direction for the signal to follow. When I first had it hooked up I had the direction of the cable reversed, hence the lack of bass. Maybe "polarity" isn't quite the word, but I don't know what else to call it...
Dave

 

[Kimmo Jaskari]

Uhh... ok, I'm a huge doubter of all things like "cable directions" etc. I might possibly accept an extremely minor marginal microscopic improvements if I really stretch, assuming some fairly out there theories I've read about fall into place, but hardly anything revolutionary. A cable isn't a diode... it conducts electricity in both directions.

Perhaps something else changed when you moved the cable. If your connection wasn't good at first but it got fixed when you unplugged it and replugged it? Otherwise I'd be tempted to attribute it to placebo effect, but not if the difference was as major as you say.

I read sloppily and assumed this was one of their passive models being fed by an amp and normal speaker wire, sorry for confusing the issue.

 

[Dave Jewett]

Kimmo,
Yeah, I had my doubts, but it definitely made a large difference in my case. When I had it reversed I got some sound, but it mostly just caused the objects in the room to resonate. After reversing it I don't get any of that excess resonance, just good, clean bass.
Here's a link to the cable I bought:
AR AP053 sub cable
Do you think the direction would matter because the cable is balanced?
Dave

 

[David_D]

This is very interesting. I have some interconnects which asre supposedly directional. I conform to the advertised direction, but I've never thought it really made a difference. Maybe I'll experiment.

 

[Michael R Price]

The interconnect's ground (shield) is only connected at one end. If you plug in the wrong end there is a very loose (or nonexistant) connection at the subwoofer end, which would cause a signal loss like the one you describe because there is no return path for the signal. I guess that might have been the problem, certain cables are made that way and I don't know why.

 

[Mark Tranchant]

The interconnect's ground (shield) is only connected at one end. If you plug in the wrong end there is a very loose (or nonexistent) connection at the subwoofer end, which would cause a signal loss like the one you describe because there is no return path for the signal.

With only two connectors, if the ground were not connected at one, it wouldn't matter which way around you put it, you'd still only have one connection. The difference would be whether the shielding was at subwoofer ground or amp ground. This technique is sometimes used to avoid ground loops, using the mains earth as the return path. The alternative is to lift the mains earth from the equipment, which is potentially (:b) dangerous.

I'd suggest that you had a dodgy connection on your first attempt, or possibly flipped a phase reversal switch on the subwoofer during the re-connection. I'll bet (reputation not money...) that if you try changing ends again, the sub would still work fine.

I am convinced that cable directionality is inaudible and a marketing tool. One day, I might build a cable with a diode inline for the ultimate directional cable - I would not expect to be able to hear the difference between the positive half or the negative half of most recordings.