Crown XLS 1000 hisses with nothing connected.

[But it Hertz]

I just picked up my first proper amp, a Crown XLS 1000.

I'm going to be using it to power a pair of SLA's in the living room.

The SLA's aren't built yet but I'm playing with the amp in my office with some old speakers of mine.

There seems to be ALOT of hiss from the amp even with nothing connected. It's going to drive me INSANE. I know it already.

Is this normal or do I have a dud?

Seems rather disappointing.

[AntonZ]

2x500W is quite a lot for the living room, especially for high efficiency cabs like SLA's. You may want to use a smaller amp for that? The XLS are intended for PA application, playing a lot louder. The hiss would probably hardly be noticed there, as a PA system will typically run in a larger room with a lot more background noise.

[But it Hertz]

Still crappy though. Imagine a speech at a wedding or whatever.

I at least expected it not to hiss with the volume turned all the way down on the amp.

[BrentEvans]

Still crappy though. Imagine a speech at a wedding or whatever.

I at least expected it not to hiss with the volume turned all the way down on the amp.

What type of speakers do you have connected to it?

[But it Hertz]

What type of speakers do you have connected to it?

I'm embarrassed to say I'm between speakers right now... I just set them up with some car 6x9's in a couple of boxes I made.

Apart from the embarrassment factor they actually sound quite good... considering.

Parts for SLA's in the post as we speak.

[Grant Bunter]

500W is the 2 ohm load.
It should be more like 215W @ 8 ohm load. Which is still a lot for home use.

Are you saying just the speakers are hooked up and with no input at all there is hiss?
If there is an input lead, is it long and unbalanced? Or poor ish quality and near power leads?
Obviously you think it's the amp, but just trying to identify other possible causes...

[But it Hertz]

Yeah, I know it's over kill for the home but I thought I would be future proofing myself.. especially as I'll be building some bigger speakers down the road.

So yeah. Nothing connected except for the speakers and I get very noticeable hiss with the volume turned all the way down on the front of the amp.

Hard to quantify but too much for the living room for sure!

At the moment I'm just testing with unbalanced line level inputs from a PC... as expected that introduces more hiss... but the amp is hissing on its own as above.

[BrentEvans]

At the moment I'm just testing with unbalanced line level inputs from a PC... as expected that introduces more hiss... but the amp is hissing on its own as above.

Is it hissing with nothing plugged into the ports, or with something plugged in but the volume all the way down?

Also, with your SLAs, you can wire in series to reduce sensitivity (which reduces the volume of the hiss), and then gain back the volume with power handling. otherwise, that amp will be too stupid loud anyway.

[But it Hertz]

it is hissing with nothing plugged in and the volume controls on the front turned all the way down.

[Ryan A]

Might be noise coming from the AC plug...have you tried a different outlet? Just guessing here. Sometimes other appliances or electronics connected to the same circuit can introduce noise.

[Bruce Weldy]

I have three XLS amps....and they are all very quiet....much quieter than the xti that I have.

Go into the dsp and make sure everything is set correctly. If so, then find someone with some other speakers to try it with....in another setting.

If that fails, take it back.

[But it Hertz]

I just checked. Factory default is Stereo Bypass... and that is indeed how it is set.

It is brand new out of the box (just this afternoon).

I'll have my SLA's built in a couple of weeks. Still waiting for parts but I'm going to start on the back & sides tomorrow.

I'll be able to check it out properly soon enough.

I would have thought that the SLA's would make it sound worse being more sensitive.

Reading reviews on these amps people rave about them. Plenty of people using them at home... I must have something wrong. Strange.

[But it Hertz]

I'm probably totally over analysing this now but I just put a scope on the speaker output of this amplifier with nothing connected and with the volume controlls turned right down.

The results really surprised me. I have an approx 400kHz ripple at about 0.6v always there. I wonder if this is normal? Must be the Class D "sampling" frequency?



Settings are 1 microsecond per division horizontally, and 0.2v per division vertically...

Freq = 1/t
Freq = 1/2.5 micro seconds
Freq = 1/0.0000025
Freq = 400,000Hz.

I doubt this signal would travel far down a speaker cable but what does everyone think? Normal or not?

[But it Hertz]

I have also tried my best to measure the hiss. Using the amp with nothing connected, turned all the way down and with only one speaker connected...

I held my SPL meter about 12 inches from the speaker. I waited for the ambient noise to subside and held a piece of paper in front of the tweeter blocking the SPL meter.

It is difficult to get a steady reading because of traffic noise tonight but I reckon I have about 2.5 to 3 dBa of measurable hiss that the piece of paper blocks!!

[Tom Smit]

I don't have any experience with said amp, but I would think that something is wrong. Is the noise still present when the amp is presented with a signal such that the music/speech overcomes the noise? As an aside, I use an amp through which one can hear hiss when it's turned up to 7 or more. SLAs willl definitely show the noise, even more so than your 6x9.