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[raider]

Hi, I have an Asus notebook which I would like to connect to make it into a low cost "home theatre system" for the interim. I don't want to get an AVR at this stage as I am saving for the Yamaha AVR (cost more than I can afford at this stage) that I really want.

I have 2 sets of a cheap class D amplifiers I bought from ebay previously. I do have an existing bookshelf speaker, an existing centre speaker and an existing subwoofer.

Can I use an Asus Xonar U7 soundcard and connect as follows?

Laptop -> USB -> Asus Xonar U7. The Asus Xonar U7 has 2 x RCA out, 1 x 3.5mm line out for side, 1 x 3.5mm line out for centre.
http://blogs.lyceecfadumene.fr/informatique/files/2013/12/E8237_Xonar-U7-manual.pdf

and then...
Asus Xonar U7 -> 2 x RCA out to RCA input of Class D amplifier no.1 -> bookshelf speaker
                      -> 1 x centre line out to RCA input of Class D amplifier no. 2 -> centre speaker

I have JRiver v20.

Will this work?

Thanks

[raider]

Any feedback?

[mwillems]

I do something very similar with the Asus U7.  One thing to be aware of is that the U7 has a stereo RCA, and three sets of stereo 3.5mm jacks, one for RL/RR, one for SL/SR, and one for C/LFE.  That means the center output is shared with the Sub output.  If that's a problem for you, you can work around it using channel mixing in JRiver's parametric equalizer because it sounds like you won't be using all eight channels the Asus provides.

Not sure where you're located, but a fair proportion of the forum members and devs are in the U.S., so you're unlikely to get a reply between 11pm and 3am on a Friday night 

[raider]

Many thanks for your reply It did not come to my mind that it was actually midnight at the other side of the globe! I am in down under Australia.

Oh yes. It seems I left out the sub woofer in my original question. I would like to use that subwoofer in the chain as well.

Could I do this then....

Asus Xonar U7 -> 1 x centre/LFE line out to RCA input of class D amplifier no. 2 -> Right channel go to centre speaker. Left channel go to subwoofer.

Will this work?

I don't have any side surround speakers at the moment (saving money for these + the AVR) so won't be using the other stereo outputs on the Xonar U7.

Appreciate some advice.

Thanks again

[mwillems]

Many thanks for your reply It did not come to my mind that it was actually midnight at the other side of the globe! I am in down under Australia.

Oh yes. It seems I left out the sub woofer in my original question. I would like to use that subwoofer in the chain as well.

Could I do this then....

Asus Xonar U7 -> 1 x centre/LFE line out to RCA input of class D amplifier no. 2 -> Right channel go to centre speaker. Left channel go to subwoofer.

Will this work?

That will work as long as your sub will accept an amplified input.  If it needs a line input you'll need to run left RCA out to the sub instead of the amp.

[raider]

Ok. I am not too sure about this one....the sub is a Velodyne Impact 10 with a RCA input (L) that says "LFE in" and another RCA input (R) that says "Line input"
http://velodyne.com/pdf/impact/ImpactManual.pdf

Can the Asus's centre/LFE channel be connected via a 3.5mm cable to 2 x RCA plug...out of which...

the Red RCA plug goes into the class D amplifier and then the speaker output from the right channel of the amplifier goes to the centre speaker. In other words, the class D amplifier only has 1 Red input connected and only 1 right output used. The white input and the left output is not used at all.

the white RCA plug then goes into another cable which splits into R and L RCAs and both goes into the RCA line input of the sub woofer.

Will this work?

[mwillems]

come to think of it....the centre speaker has 2 binding post red and black...which one should I connect to?

If they're binding posts you'll need to connect to both of them from an amp.  If you don't complete the circuit you will get no sound.

You seem to be confusing line level and speaker level signals.  RCA and 3.5mm connections are line level connections, meaning that they're used for interconnecting audio equipment, but cannot be hooked directly to a normal passive speaker.  Active speakers will take a line-level input, but they'll have an RCA or 3.5mm jack if that's the case.  Each RCA connector is one channel of sound, and each 3.5mm jack is typically two channels of sound.

By contrast amplifiers typically connect via wire to speaker binding posts with an amplified or "speaker-level" signal.  To get one channel you have to connect both binding posts because the red one is the positive or "hot" wire and the black one is the negative wire.

http://stereos.about.com/od/systemsetup/a/How-To-Connect-Speakers-To-A-Receiver-Or-Amplifier.htm


EDIT: looks like you edited your post.  You're on the right track, you'll just need to check it and make sure that the Red RCA is the center and not the sub if you see what I mean.

[raider]

Many thanks for your great explanations. I have saved the entire post for my future reference.

Just asking too...the class D amplifier won't suffer damage if only one channel is being used...correct?

[mwillems]

Many thanks for your great explanations. I have saved the entire post for my future reference.

Just asking too...the class D amplifier won't suffer damage if only one channel is being used...correct?

No it should be fine as long as you don't try to bridge the outputs or something (i.e. don't try hooking up both outputs to the same speaker, just hook up one output like you mentioned).

[raider]

Many thanks again. I will try this setup once I have the xonar soundcard. Cheers.

[raider]

I have now tried the Asus Xonar U7 and I am pleased to say that it works very well with JRiver. The centre speaker works really well with the output from the Xonar.

The Asus Xonar U7 is connected to two integrated amplifier. the first amplifier powers the front left and right speaker and a subwoofer from its preout. the second amplifier only powers the centre speaker. I wanted to maintain the preout to sub woofer as I use the first amplifier for stereo music when I am not watching video.

I have been experimenting with the JRiver PEQ feature and find that if I do the following, I seem to be getting a more dynamic sound effect. Is this the right approach?

1. Add Sub to Front Right
2. Add SL right to Front Right
3. Add Rear right to Front Right
4. Add Sub to Front Left
5. Add SL Left to Front Left
6. Add Rear Left to Front Left

What are the other settings I should apply?

Thanks

[raider]

Bump. Any one able to help on this one?