Benobs

XLS DriveCore - Dealing with mono input in bridge mode for subwoofer application.

6 posts in this topic

I just added an XLS2000 to my HT system to power a passive sub-woofer I had laying around. My main speakers are powered by a Rotel Integrated amplifier.

My concern right now is the mono signal required by the XLS in bridge mode. Right now I have a work around by using the dedicated output from a sound card, but my next upgrade on the list is a quality DAC (stereo only). No need to specify that I use unbalanced outputs.

Do you guys have an idea that could save me some headache?

Here are my current alternatives :

1) An external "mixer" that mix left and right into a mono out. (Any suggestions appreciated)

2) Go stereo and plug each voice-coil (dual 4ohm) into 1 channel. (I dont think its a good idea...)

3) Parallel the voice-coil (total is 2ohm) and use 1 channel only (not sure I will get enough power)

4) Make an home-made passive stereo to mono adapter with resistances to protect the DAC. (Ouput level may be to low)

5) Sound-card.... (Currently, no sound-card seems to fill my needs in terms of quality and flexibility...)

*What happen when you run the XLS in Stereo Mode but a speaker is plug in bridge?

Thanks all!

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DO NOT USE THE "BRIDGED OUTPUT" CONNECTION UNLESS THE AMP IS IN BRIDGE-MONO MODE!

I suggest you just go stereo and place (1) 4-ohm coil (load) on each channel. Based on the info given, that is your best option.

Any small two channel mixer can be used to force mono (like a Behringer XENYX 502): Plug your DAC's left output into one mixer channel, and itsright output into another, make sure the "pan" (balance) knobs are centered and both signals will be combined at the mixers LR outputs. It doesn't mater which mixer output you use, (L, R, or both) they will have the same summed/combined signal.

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Well, one more option you didn't consider...

I don't know which sub you have but I understand it has dual 4 ohm voice coil, then connect the voice coils in series and then you have an 8 ohm driver you can safely power with the 1300W the XLS2000 has to offer in bridge mono mode.

Other then that you need to check if the signal coming out of your Rotel has enough voltage otherwise it might be cheapest to get a small mixer like the mackie 402-vlz3, for the 100$ it costs it can boost the signal to the required levels and another important feature for the low end drivers and that's summing the signal from both channels.

Avi

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Beeing too poor to invest in unneeded equipment, i'd run in stereo mode myself. 8 ohms bridged and dual 4 ohms will give you the same total power. So use dual, since you have all that is needed already. You will only need one more speaker cable. The 1/4 and RCA input connectors can act as a loop thru to your other amp.

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Thx, this is what i thought.

I will probably add a mixer to my wish list, it will give me the possibility to use the Rotel pre-out, sum it to mono and keep total control over the sub-woofer gain (Right now, the volume is ok/quiet with the gain set at max on the XLS2000).

Until I find a DAC, I'll test dual to see what kind of sound i get :)

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