Unused Amp input

[loupy31]

Hi All,
I have an XPA3 and an XPA5, If I dont use all the inputs, for eg: only use 3 of the 5 in the XPA5 or only use 2 in the XPA3.
the unused amp, will it be damaged if no speaker load on it.

Peter

[sharkman]

This concern comes up occasionally and some who only use 2 out of 5 channels were told if they crank it up to levels above 200 watts, the channels in use could draw more current than designed for and over time it could stress the electronic components in those channels. You would need to be listening at or above reference levels, or well above 100 decibels depending on the sensitivity of your speakers, to stress anything.

I have an XPA-3 that I only use 2 channels of. I find that I don't like volume levels above 100 decibels, and I'm comfortable with under 90. With my speakers rated at 91db sensitivity, that means I'm using only a few watts at most out of 200 per channel.

[loupy31]

So It wont damage the amp, having no input and no load

[loupy31]

So It wont damage the amp, having no input and no load.

[MUGEN]

I ordered a XPA-5 but will only be using it for LCR until I decide to ad rear channels, which maybe awhile.


From another thread on this issue.

Nov 23, 2009 22:30:27 GMT -5 lonnie said:

The short answer to the question is yes, you can use the amp with fewer channels running than what it was designed to do. As long as you stay within the power specs we state and give the amp plenty of air to cool, this won’t be an issue.

However………..

This is a question where the answer is both easy and complicated at the same time. You see when you use less than all five channels. All the energy of the power supply (well in excess of 1K watt) is directed at however many channels that are being used (which are designed to dissipate 300 watts RMS). This means the rail voltage on a specific channel goes up significantly which causes that channel to produce more heat (because it is dissipating more energy). Thus it is going to need adequate cooling to keep from stressing the channel(s). With the increased rail voltages you get more power and as long as you stay within the rated spec, no problem. But how do you know if you are within the rated spec? Honestly there isn’t any way for the average Joe to know without a lot of sophisticated gear to measure the output. So if you plan on driving the amp hard, you could over drive the module which isn’t good. But if you listen at a reasonable level, say something short of your ears bleeding then no problem. Honestly there are a lot of other things that should be considered, like the impedance curves of the speakers (how low do they dip), what other equipment is in the system (are they using an EQ with a lot of boost), etc. but we won’t go down those roads (not enough time). So there are a lot of factors involved in what we recommend and since we never seem to have all the information, I always tell everyone to err on the side safety. Stick with what the equipment was designed to do and everyone wins. I have told a lot of people that we don’t recommend using the multi-channel amps for strictly stereo or mono-block use. If you want a high power stereo or mono-block amp, then that is what you should buy. Using anything in a manner other than what it was designed for is never a good idea. ;D

emotivalounge.proboards.com/index.cgi?action=gotopost&board=amps&thread=7639&post=112676

[slbenz]

No problem. Most of the time, I run my XPA-5 in two channel even though it is set up for five channel.

[roflcatdown]

Nov 2, 2010 5:19:44 GMT -5 loupy31 said:

So It wont damage the amp, having no input and no load

The short answer is... Maybe.

If you're not using the power on a channel, then the voltage from the power supply can go elsewhere. Pretty much the two channels being used can now go over 200 Watts (300 @ 4 ohms)... I believe Lonnie has stated previously that the heat sinks are really only capable of dissipating the 300watts RMS per channel.

So, like others have said. If you crank it you could hurt the channels being used over time. The unused channel will not be drawing much power, so it's really only going to passively experience heating from the other amp boards near it.

[aussie]

Really depends on how you have the amp/s set-up and how much you drive them.

But as much as some folks say never use just 2 channels on a multi-channel amp what happens when you use a pre/pro like the UMC-1 or a AVR in just stereo mode or some other 2 channel mode?

[roflcatdown]

Nov 8, 2010 15:20:08 GMT -5 aussie said:

Really depends on how you have the amp/s set-up and how much you drive them.

But as much as some folks say never use just 2 channels on a multi-channel amp what happens when you use a pre/pro like the UMC-1 or a AVR in just stereo mode or some other 2 channel mode?

Short-term use it's not a problem. Long-term at extended volume pretty much every manufacturer (Including Emotiva) will tell you it's a bad idea.

When you're not using a channel, the power that it would normally use is available on the rail for the other channel/s. If the power draw exceeds your cooling ability, you're risking if not causing damage to your hardware.

If you look at the XPA-3. It's 200 Watts RMS @ 8 Ohms, or 300 @ 4. So looking at this would be able to infer that cooling-area wise each channel has sufficient cooling for 300 Watts RMS minimum. Running an XPA-3 2 channels should yield a max RMS of 300 Watts @ 8 Ohms. It probably would be mostly "OK"

An XPA-5 on the other hand... Well, you're taking the rail voltage normally reserved for 5 channels and funneling it into 2... So, theoretically you could potentially shove 500W per channel through amp modules designed to dissipate heat from 300W per channel.

At least, this is how I understand it.