XPA-5 and adding XPA-1 worth the upgrade ?

[ddmex101]

I am planning of purchasing 2 XPA-1 for my front speakers. My audio rack is about 15 feet away from my Right speakers and 4 feet from my left speakers. The plan is to install XPA-1 (1) foot from each speaker. My system consist of LMC-1 XPA-5 and the ERC-1

I am planning of purchasing (2) XPA-1 for audio listening. 90% of the time I use my system for 2 channel listening. If I upgrade I need a Pre-amp with balance input and currently waiting for the XSP-1 so $2000 for amp and $700 for preamp with balance input. Is it worth the upgrade?

or will the XPA-2 be just as good as the (2) XPA-1?

thanks in advance!

[matt]

At less than 50 feet, I would keep the amp closer to the source (XSP-1) than the speaker. Speaker wire, carrying much stronger current, will not be susceptible to interference like RCA can. XLR is designed to reject interference by cancellation, but I do not think that it is as good as keeping its run short and using speaker wire to fill out the difference. Although with XLR, you probably would not be able to tell the difference unless you run them by some A/C cords, wireless transmitters, fluorescent ballasts, or other strong sources of interference. One advantage to separating the amps may be to distribute the A/C load, depending on how the circuit is wired. Although it could introduce ground hum if the building is wired improperly or their is a faulty appliance connected to the A/C circuit.

I own the XPA-5 and XPA-1. They both sound great, but for larger speakers and at higher volumes, I recommend the XPA-1 for extra headroom. I am currently using RCA with the XPA-1, but if you plan on using XLR, the XPA-1 may have an advantage over the other XPA amps. The XPA-1 is currently the only one with a differential reference design. Although I am not sure how that will affect the sound.

[ddmex101]

Thanks Matt for the info. I can only put the XPA-1 beside each speaker due to space. I have a Martin Logan quest therefore I consider it a
large speaker may be I will benefit with XPA-1 but have to use long XLR cables but the speaker wire be shorter. I need a preamp with balance input I currently own the LMC-1 may be ill will just wait for the new pre-amp.

[matt]

You are welcome.

I recently found something that might be interesting to you. It may be useful to me when I want to move my sub further away from my A/V equipment. XLR noise rejection works by sending the audio signal twice, with the second copy reversed in polarity. The assumption is that noise will be added to both wires in equal amounts, so the device receiving the audio will balance any difference between the wires. This removes the noise that was added to the cable.

If noise is somehow not evenly distributed between the two wires, then the noise rejection will not work as well. I am not sure how much of a practical problem this is, but I guess if there are sharp bends in the XLR cable and noise somehow is concentrated on any of the bends, then noise could potentially be added to one of the wires more than the other. I imagine that this is a fairly small problem unless there are local sources of noise, such as A/C wires running near by. Even then, I am sure that the difference would be too small to notice.

Blue Jeans Cable has a Star Quad XLR cable that doubles the signal paths for the two audio signals. In theory, by doubling the normal and reversed audio signals, noise will be more evenly distributed between the normal and reversed signals, making noise rejection more accurate. When adding additional isolated wires of a signal, you increase the capacitance, which can have a negative effect on the audio quality.

The cable:
www.bluejeanscable.com/store/balancedaudio/index.htm

See "Speaker Wire Capacitance" and "Cobra Cable" for warnings about adding extra capacitance:
www.roger-russell.com/wire/wire.htm#capacitance

I would stick to regular XLR cable unless you have to run your cable near any strong noise sources. In my setup, I make sure that A/C wires are more than 5 inches away from the audio cables. I do not use any wireless devices near them. If I had to, I would keep them more than 3 feet away. This includes an iPhone dock, as cell phones can add lots of noise to audio equipment.