Review and Measurements of Crown XLS 1502 Amp

[Rahan]

I wish a could live without music more than a day.

 

[aschemkes]

Yep - crank the gain too much on the power amp, and you can potentially hear the noise floor .... which IMO is why there are reports of Hiss...

Lots of people make the mistake of running with the Gain at MAX - cos you know ... more power!... and then complain about hiss!

Totally agree and this is exactly what is going on! I WAS hearing some hiss and noise too at first installation! So I disconnected the inputs, gone was the hiss , Zero, nada nothing to be heard. Changed my interlinks/rca cables, rerouted them away from any other cables and noise "generators", turned the gain down to normal (1,4V) and gone was the hiss... The amp has a SN ratio of 100dB, impossible to hear that at listening position. (4 meters)

 

[Deleted member 71304]

Totally agree and this is exactly what is going on! I WAS hearing some hiss and noise too at first installation! So I disconnected the inputs, gone was the hiss , Zero, nada nothing to be heard. Changed my interlinks/rca cables, rerouted them away from any other cables and noise "generators", turned the gain down to normal (1,4V) and gone was the hiss... The amp has a SN ratio of 100dB, impossible to hear that at listening position. (4 meters)

But if I understand correctly one can keep the gain aprox at 50% and still drive the amp pretty loud, right? I mean it is not strictly necessary to turn the gain knobs all the way up, correct? At least this is the case in my place (25 sq m living room)

 

[Jonas_h]

But if I understand correctly one can keep the gain aprox at 50% and still drive the amp pretty loud, right? I mean it is not strictly necessary to turn the gain knobs all the way up, correct? At least this is the case in my place (25 sq m living room)

Gain has nothing to do with power.

You set the gain based on the component connected to the amp. When you have your pre amp on maximum volume, your Crown should have the gain which corresponds to the maximum SPL you want to achieve in your listening position. This will give you the best signal to noise.

 

[Deleted member 71304]

Gain has nothing to do with power.

You set the gain based on the component connected to the amp. When you have your pre amp on maximum volume, your Crown should have the gain which corresponds to the maximum SPL you want to achieve in your listening position. This will give you the best signal to noise.

So if I understood you correctly, I should start with Preamp to max and gain to min and the turn the gain up 'til it reaches a volume I could consider as an acceptable maximum from my listening position... richtig?

 

[Jonas_h]

So if I understood you correctly, I should start with Preamp to max and gain to min and the turn the gain up 'til it reaches a volume I could consider as an acceptable maximum from my listening position... richtig?

That is how I do it. I reach reference level in my theater when my surround processor is at 0dbFS.

 

[GabrielPhoto]

I thought that was the opposite of what we are supposed to do..now I am curious.

 

[Deleted member 71304]

To be honest I have not really understood the difference between gain and volume- I mean I know they are not the same but never grasped much of the explanation...

 

[Theta]

In my case the hiss is not relevant, like stated above it only appears when the Crown is on and the preamp is off.
Once I turn on the preamp there is no hiss and it sounds just great. It is really amazing for 430€ (I have compared it with a Hypex and I cannot hear a difference, not that I have particularly good ears but it is certainly worth a try)

I also own a Crown XLS 1502 amp 2d generation; works for me great with the RME ADI as a preamp. I have so called "better amps" but no one including me needs better.

 

[staticV3]

To be honest I have not really understood the difference between gain and volume- I mean I know they are not the same but never grasped much of the explanation...

Input voltage*Preamp gain*Amplifier gain*Loudspeaker sensitivity=Output volume (SPL)

 

[GabrielPhoto]

I have always been told from research that you leave the amp at max and use the pre to adjust the level needed so looks like the opposite has been said here

 

[staticV3]

I have always been told from research that you leave the amp at max and use the pre to adjust the level needed so looks like the opposite has been said here

Most Amps nowadays have a pre built in (e.g. Crown XLS 1502) and most DACs nowadays can function as DAC+pre thanks to built-in digital atenuation.

In that situation, you'll get the best SNR by maxing out the DAC and attenuating using the Amp's built-in pre.

If you have e.g. a CD player plugged into an external pre, plugged into an Amp with its own volume knob, then it does not matter if you use the external pre or the Amp's built-in pre to control volume.

 

[Jonas_h]

I have always been told from research that you leave the amp at max and use the pre to adjust the level needed so looks like the opposite has been said here

Search for research regarding gain structure. Lots of info online. Amp gain adjustment is a one time Thing. After it has been setup you will of course use the pre to adjust the volume.

 

[Clmrt]

I have always been told from research that you leave the amp at max and use the pre to adjust the level needed so looks like the opposite has been said here

No. Amps have attenuators. Plugging an amp into your speakers with the gains at max will display whatever noise they make through the speakers. Usually pretty quiet. But you want the signal, not noise, so by attenuating at the amp you drive noise down, then hit it with a stronger signal to compensate. Better Signal-to-Noise ratio.

If you simply run the attenuators wide open, all the noise will still be there, and your signal from the preamp / source will have to be reduced. You want signal, not noise.

If you do it right by attenuating noise at the amp, but cannot get the volume you are looking for, then you have to open up the attenuators on the amp, leading to compromise. Granted, this usually happens with little to no audible penalty.

I run an old AB International pro amp off my Marantz NR1510. I have to keep the attenuators wide open because that amp needs a strong signal. Even so, it is nearly silent at 3 inches from the tweeter. Bringing the attenuators down quiets it down to nothing, but then I run out of preamp signal.

Then there's input sensitivity...

 

[GabrielPhoto]

@Clmrt @Jonas_h @staticV3
But we want to maybe measure with a scope to make sure we don't clip the signal we are sending to the preamp in the quest to not run the amp at max gain?
Hope that made sense


Also, for example, if I set my AVR LFE to -10 then my MinIDSP channel connected to a crown 1002 or NX6000 is set to say -6. I am better off maxim out the MiniDSP to 12 then lowering the amp for a better noise signal ratio?

 

[calvados.boulard]

Gain has nothing to do with power.

You set the gain based on the component connected to the amp. When you have your pre amp on maximum volume, your Crown should have the gain which corresponds to the maximum SPL you want to achieve in your listening position. This will give you the best signal to noise.

Is there a danger when having your pre-amp set to maximum volume that it is clipping or distorting on the output from the pre-amp, or input to the Crown? I've done similar, but set my pre-amp to around 3/4 volume, then adjust the Crown to what would be maximum listening volume at my listening position. I'm wondering if re-doing this with the pre-amp set higher in volume would increase the sound quality a smidge. FYI, in my current setup the Crown gain is set 3 'ticks' up from minimum, (or approx 7 o'clock), so I'd be lowering the Crown further if I did this.

Thanks,
C.

 

[Neekomax]

I'm using the Crown XLS-1502 in my system, and it's getting the job done. It only has to drive the coax mid/tweet array, as the 8" subwoofer drivers each have their own plate amp on the back on the speaker. I originally used this amp to power my drummer's stage monitor (he needed extra oomph compared to our active wedges power outputs).

In regards to the discussion, I have my 1502 set at like 2:00, which gives me my maximum desired in-room volume when my Wiim Ultra is set to 100 (max). The SMSL M-500 DAC is set to 36 out of 40.

 

[Neekomax]

I wish a could live without music more than a day.

You could, it just wouldn't that great a day

 

[Clmrt]

@Clmrt @Jonas_h @staticV3
But we want to maybe measure with a scope to make sure we don't clip the signal we are sending to the preamp in the quest to not run the amp at max gain?
Hope that made sense


Also, for example, if I set my AVR LFE to -10 then my MinIDSP channel connected to a crown 1002 or NX6000 is set to say -6. I am better off maxim out the MiniDSP to 12 then lowering the amp for a better noise signal ratio?

Absolutely that makes sense. You are on the right track. You want your preamp driving a clean signal into an amp that is not also magnifying noise. Every step of the chain has an opportunity to add noise, and overdriving one of them (output or input) rips it all down.

 

[JeffGB]

I've been running a Crown XLS 1500 for years. It's now driven by an SMSL DO100 balanced output into a Schiit Magnius and then balanced to the Crown. It's in a near field situation with the Crown controls set to 100, the DAC set to 100 and the Magnius set to high gain and there is zero noise, even with my ear to the speaker drivers (JBL A130's). My source is a PC running EqualizerAPO to correct for the JBL deficiencies. I'm always reading about people having noise with the Crown but it must be from their source or they are using very high efficiency speakers.