[Martin]

Hi all!
 How does one incorporate a subwoofer into a
2 channel system. I don't have a seperate sub out
at the back of the CD/DVD player. My interconnects
run from the CD to TLPn to Aksa 100n and then
speaker cables to speakers.
  Can I build a "Y" and run it out of the TLP
to send a signal to the sub amp?
  Will this cause signal loss?
 Any imput would be appreciated.
Thanks
Martin

[PSP]

Martin,
I run a sub with my TLP and it works very well.  If you look at the top of the volume pot (attenuator, whatever you are using) there are two signal wires for each channel that go to the TLP input.  I ran a second set of signal wires (tightly twisted, of course) to two Sub Out RCAs (my Marchand XM-9 crossover does the channel summing).

Because this simple approach leaves open the possibility that noise in the crossover and/or interconnects to the crossover could inject noise into your TLP, I put a series resistor (somewhere around 1k - 4.7k ohms) in the signal path to the sub out RCAs to attenuate this noise simply as a precaution.  If you use too much resistance you will not be able to turn up the gain far enough on your sub amp; if you use too little resistance there might not be enough attenuation of noise from the XO and interconnects.  This is something that you can easily determine for yourself.
 
Somewhere many posts ago, Hugh recommended taking the sub out signal before, rather than after, the TLP because the tube may not pass the very lowest frequencies.

Hope this helps,
Peter

[doug s.]

run line out from tlp to a crossover (like the marchand); then hi-pass to the 100n monitor amp, low-pass to the subwoofer amp.  if using a powered sub, use the rca inputs to it, & set its internal x-over at its highest setting - use the active x-overs' electronics for more transparency...

doug s.

[Oz_Audio]

Hi Martin,

Thanks to the Home Theater set, adding subs is one of the most missunderstood areas of Hi Fi.

The Sub out from your DVD will probably be set to either 100 hz, 120 hz or 80 hz. and will only work as designed with DVD's with 5.1 encoding,  not CD's with no encoding.  So when listening to CD's either non of the sub frequencies will be coming out of the sub out, or the whole frequency range.

The next problem is powered subs.  These have RCA inputs that crossover the frequencies at the desired point and then send the lows to its own amp to drive the sub and some outputs to go the the main power amp for your main speakers.  The crossovers are normally First order or 6dB/octave, if you turn your mains off you will still hear voice from the sub - not good.  Some with have Second order or 12dB/octave, stll not good enough.  What you need is Third order, 18 dB/octave or Fourth order, 24dB/octave.  Every few powered subs have these crossovers.

The best way to add a sub is the have the interconnects from the Pre Amp to an active crossover of 18dB or 24 dB then going to the separate amps for mains and sub.  This works for 2 channel or 5.1/7.1  If using multi channel, turn the Sub Off on the meneu of the DVD or 5.1 amp if using one.

There are plently of DIY crossovers on the net (read up on the subject at www.linkwitzlab.com and http://sound.westhost.com/ ), or buy a second hand pro audio unit such as a Rane or DOD.

Adding a sub is worth while, but it will take a lot is experimenting with frequencies and levels to get the required result, and your mains may not be suitable or will need modifying, if you have normal vented mains, block the vent, the vent is onlt their for the low frequencies and it will not interact well with the sub if you do not.

The goal is to have a seemless sound with no noticable low frequencies, just natural sound (another thing you will not get from a powered sub).

Mark

[Martin]

Ok.....so how do I bring a signal to a powered sub
out of my CD/DVD if there isn't a sub "out"?
 Do I use a signal splitter on my R & L audio out of
the source...CD/DVD?
 Sorry guys, I'm not fluent in DYI audio and need
to keep it simple and I mean the Oklahoma kind of simple!
Thanks
 Martin

[AKSA]

Martin,

A signal splitter cable is just fine - one of those gizmos that has one RCA connected to the CD player and which then branches out to two RCAs;  one for the TLP, and one for the powered sub.

Cheers,

Hugh

[Martin]

Yeeeeeeeeehhhhaaaaw Hugh!
 Now thats what I call simple....but won't I have to adjust
two volume controls: one for the sub & one for the Aksa (thanks dg)?
 Why not split it out of the TLP to the sub & the Aksa?
Can I get another set of outputs off the attentuator (refering to Peters post)?
I don't understand the part about interjecting noise back into the TLP from the interconnects and crossovers.
'member...keep it simple ya'll.
 Martin

[Al Garay]

Martin,

Since the sub is powered, it will have a gain control to adjust the volume ... independently from the satellite amps.

You could add another set of ouput RCAs to the TLP and use that to connect the sub. Then you don't need a Y-adapter... do not degrade the signal to your satellites.

Good luck,

Al