Help set up Active subwoofer, No pre-out.

[A_Hodge]

Hello,

 

I have recently enquired a Kef PSW2000, which has these inputs:

 

http://imgs.segundamano.es/images/483/48399755516.jpg

 

and i have a Pioneer a-400, which does not have a subwoofer pre-out.

 

I have never connected up a sub woofer before, so the help is appreciated.

 

I understand that the easiest way would be to run speaker wire from my amp to the sub woofer and connect to the speaker wire terminals. Is it best then to have wires from the sub to the speakers, or to run the speakers in parallel.

 

But i have read that by doing this the sub woofer will be drawing power from the amplifier. Obviously i would rather the subwoofer power itself.

 

What options do i have here?

Thanks

 

Another Question, is it possible to connect both hi and low level inputs?

 

 

 

[RankStranger]

which is the Amphion Impact500 you have the option of running speaker level either via the sub to the speakers or via the speakers to the sub. If you run to the sub first this will run the signal through a low pass filter and not send a full signal to the speakers. The manufacturer recommends this for high volume use. If you run to the speakers and then the sub you get full bandwidth to the speakers and they recommend this for the best sound quality (my preference). Your's might be different but that's how mine works.

 

RS

 

[A_Hodge]

Yes i would idearly like to get the full bandwidth to my speakers as they are kef 104ab's. i would like to get a more subtle bass when listening to music, and more "boomy" bass when playing games.

 

For music i use a DAC to AMP

for games i use XFI > 3.5mm jack to RCA > AMP

 

How would i go about setting the speaker wire from the speaker to the sub?

 

[rom661]

With all due respect to the prior post you are running the sub in parallel off of the power amp, regardless where you make the connection. You would have to run the signal through the sub crossover and out of a separate output for it to be a series connection.

 

The subwoofer speaker level input is a very high impedance input. Compared to your 4 or 8 ohm speaker, it doesn't exist for all practical purposes as far as your amp is concerned.

 

This is my favorite way to run a sub in part because your amplifiers low frequency sonic signature is at least partially present, making integration easier . Let the speakers run full range and bring the sub in below them. Bring the crossover setting up to what seems right. Don't pay too much attention to the frequency on the dial; there are too many variables. If you don't have a meter, trust your ears. Once you're close there, play with the phase settings and see if different settings sound more "right". These are all interactive so it's best to go back and forth. Sometimes the "wrong" phase can help compensate for room nodes as well.

 

This is kind of an art in itself but a little time and you should get decent results. A well set up sub not only provides low frequency music information, it also provides the brain with spatial information; it can really make a soundstage bigger and more believable.

 

Good luck

 

Rick

 

[A_Hodge]

Hi thanks for the information.

So just to clarify I would run speaker wire direct from AMP > Speakers and AMP > Subwoofer, by use of the binding posts.

 

or is it better to run AMP > Subwoofer Hi level in/ Hi level out > Speakers. So to use the sub crossover.

 

I am concerned that by using the high level input my amp will not be powerful enough, or will the sub still be self powered.

 

 

 

 

 

[Part-Time Audiophile]

I think it's considered best to run the following (as you mentioned):

 

Amp >> Subs

Amp >> Speakers

 

Do not use the line level inputs on the subs. Unless ....

 

Well, I have a preamp (which you don't?) with two sets of line outs. One goes to my amp and one to my subs. Most would argue that this means that the subs "don't get the character of the amp" and therefore would be harder to integrate, but since I use a pair of OTL tube amps, this is probably a good thing. YMMV.

 

Note that doubling up on the posts on the amps might be a tight fit for spades. If your posts do both bananas and spades, might want to mix it up.

 

[A_Hodge]

Line level is the red and white RCA correct?

and Hi Level is the speaker wire?

 

Currently i have banana plugs, i will try use some spades as well.

 

So i will have:

 

negative left -left speaker negative

negative left -Left negative on sub woofer

 

positive left-left speaker positive

positive left-Left positive on sub woofer

 

negative right-Right speaker negative

negative right-right negative on sub woofer

 

positive right-Right speaker positive

positive right-Right positive on sub woofer

 

So i dont have to worry that the sub will be drawing power from the amp?

 

 

 

 

 

[rom661]

No need for your concerns. There is nothing you can do that would cause your subwoofer to no longer be powered short of taking out the amplifier in it and rewiring it. Trust me.

 

This has no affect on your amplifier. Your speakers are low impedance/resistance. The speaker level input on the subwoofer has very high input impedance. This means that virtually all of the current is flowing into your main speakers. Your amplifier will never know the difference. It's like sticking a hose into the Mississippi river. Absolutely no meaningful effect on your power of the power amp.

 

[A_Hodge]

Thanks guys, thats pretty much everything cleared up!, one last question, is there a preferred type of speaker wire for a sub?

 

[rom661]

My opiinion only, of course. Hopefully this won't start a flame war on cables.

 

I am an advocate of cables making a difference, sometimes very significant, and I include both digital and analog. However, and I have played with it a lot, I don't find that to extend to subwoofers. Low level or high level, I just don't hear anything.

 

Richard Vandersteen has a short pigtail of Audioquest Sky (2700/M) coming out of the crossover boxes that roll off the input to his speakers that have a self amplified subwoofer. This carries the full range signal. The cable he gives you with his external subs, the one which only accepts speaker level inputs, is anything but expensive. Richard is know for saving money anywhere he feels it doesn't much matter and spending it where he does.

 

So no, in my opinion, save your money for where it will buy you more performance.

 

[RankStranger]

I don't actually understand the technical aspects, I was just going by what the owner's manual said and my Finnish isn't as good as it could be.

 

I will vouch for saving your money on speaker wire though. The nicest sub I ever heard was a REL and the cable they supplied had a nice connector but it was a pretty light, basic cable.

 

RS

 

[rom661]

Your Finnish is far better than mine if you even figured out from the manual that it's a subwoofer.

 

Your point about REL is totally valid. I've been a dealer for many years and once substituted a more serious cable with a Neutrik connector. No difference that I could tell.

 

Happy listening and holidays.

 

Rick

 

[Part-Time Audiophile]

Cables may make a difference, but I've never had them make a difference on a sub. YMMV, but I wouldn't expect it to. Great opportunity to try out a set of Blue Jeans Cables.

 

[rom661]

Years ago I had to change out the crossover on a Wilson Watt/Puppy. Wilson has always had a close relationship with Transparent and it was perceived that there was a synergy between them. Once I got into the thing, I think a 5.1 series, I discovered that it took two soldering guns, not irons, to melt the solder on the lug that fed the woofers. The cable? Heavy gauge, multi stranded Monster car audio cable, the antithesis of "serious" cable. First I was shocked, then I started laughing. In fairness, everything else was Transparent.

 

I think all their internal stuff is Transparent now but it does make the point about the low frequencies. They maintained this worked best. It's a good reminder when I start taking myself too seriously...

 

Rick

 

Please don't take this as meaning you need a heavy gauge cable for your sub. There is very little current flow into the high impedance input so high conductivity is not an issue.

 

 

 

 

 

[RankStranger]

My Finnish is just as bad as anyone else's here. Amphion put diagrams in there and the rest I owe to google translate. I might have lost something in the translation of the series/parallel stuff.

 

RS

 

PS being a rally fan I do know the Finnish word "sisu" which means will, determination, perseverance and courage (or kurridz as they say it) which I think can apply to hifi just as well as it does to rally driving