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Crown power amp setting ?

L

lms

Active Member
I have an xls 1002 and up until this afternoon I have set the pots to around 1, sometimes 2 o'clock. This sounds pretty darn good, but today when I cranked up the volume I noticed a tad bit of distortion, I think. What I mean is that it just didnt sound all that great. Now, I don't have great gear and I'm just starting out, but have noticed that I'm starting to pick up on what sounds good and not so good. Before, well heck it all sounded great cause I really didn't have a stereo. Yeah, I have a nice surround sound system in the living room, but that doesn't count. So when my GF bought me the crown I read a few posts on the web about where to set the pots, came up with 1 or 2. Now today, and I never did this before, I turned the pots to the max and holy heck, is it just me being silly, but it sure sounds 10 time's better now then it did at 2 o'clock. Is there a reason for this or is it in my head? Cause I went back and forth, and placing the pots all the way up and letting the the pre do the rest sure sounds a whole lot better.
Thx
 
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If you don't hear any background noise (like hiss in the speakers) with them turned up and the preamp turned all the way down, then you're good to go. You were probably driving the preamp into some distortion with it turned up high and the amp down low (the output impedance of the preamp could be coming into play). I have an XLS 1502 and my attenuators on the amp are all the way up.

Some nice home amplifiers don't have input attenuators, they run "wide open" all the time - no reason a nice pro amp can't do the same thing.
 
I don't hear any noise at all. Okay that's not true, if I have the mesh pod plugged in which is close to the pre-amp I can hear a slight signal thump, so I have to unplug that before I play music. What I noticed with them all the way up is that the bass sounds fantastic, and the highs aren't annoying on certain songs. Why do they even have the pots, is that more for pa systems? Anyhoo, I'm keeping them cranked now, had no idea what I was missing.
Thanks much!
 
Yeah, "gain structure" is a big thing in the PA world - home audio, too, if you're unlucky - and having attenuators on the amps helps deal with that.

If you were trying to bi-amp your speakers with a nice little SET tube amp for the highs and that Crown on the woofers, for example, you might find that the little tube amp couldn't keep up, turning the attenuators down on the Crown would make it real easy to get them to play together. Or maybe your preamp had a lot of gain and you could only turn it up a wee bit before stuff got too loud, the attenuators would help there, too. But with a single amp driving speakers with crossovers and a normal preamp, it's not going to hurt anything having them turned up.
 
lms said:
Is there a reason for this or is it in my head?
Click to expand...
There are very good reasons to explain your experience.

In the real world, the gain of virtually every type of component is anything but constant - whether it be a source like a phono cartridge, DAC, CD player, etc. or any number of amplification devices. And each has its own optimum range in which to operate.

What you need to consider is the output level of source driving the input level of that which follows. Standard output of a preamp stage is 2V. Let's complicate that a bit. The standard output of many digital sources which are frequently further amplified by preamps like CDPs and DACs is also 2V. Some time ago, I had a GamuT CD-1 with 4V output - which I drove the power amps directly using stepped attenuators. There is almost always attenuation at some stage going on before you get to the power amp.

Your Crown amp has an input sensitivity of 1.4V. Feed it the industry standard of 2V and welcome to the land of overload distortion.

Achieving the best sound is always about matching components at every level.
 
Rooms and acoustics play a big role in this. At some point the acoustical conditions in the room start to have a noticeable impact on how things sound. Subtle room modes that go unnoticed at lower levels become clearer and change the listening environment.

Try listening again under the same conditions to replicate the sound, so you can identify the sound repeatedly. Then move stuff in the room, move speakers, add chairs with a few layers of towels along bare walls.

My point is that the causes may well he caused by something outside your amp, and these can be cheap or free to fix.
 
I think the room doesn't know/care if
  1. the preamp knob is at "7" and the power amp knob at "2", or
  2. the preamp knob is at "2" and the power amp knob at "7"
as long as the net SPL is the same/similar in either case.

Far as the OP goes, the DriveCore 2 series, of which the XLX1002 is, has selectable input sensitivity 1.4V or 0.775V. If it's at 1.4V you could change it to 0.775V and then you're really be able to rip it out with an even lower setting of the preamp volume.
 
whoaru99 said:
I think the room doesn't know/care if
  1. the preamp knob is at "7" and the power amp knob at "2", or
  2. the preamp knob is at "2" and the power amp knob at "7"
as long as the net SPL is the same/similar in either case.
Click to expand...
I don't think the room knows or cares about the knob setting either. The concept of "the all-knowing room" is an interesting one, though. Could perhaps provide some inspiration for Stephen King.
 
I'm starting to somewhat understand what is being said above. First, I really cant move anything around the room as its a multipurpose basement den, so to speak. But I do hear a difference when I drop the window shades, etc. I think one of the biggest issues is that the ceiling is really low.
In regards to the selectable input sensitivity, should I try the lower level?
Thx much.
 
Some of the crowns have internal jumpers to set the gain, beyond the knobs. It's pretty uncommon for anyone to change it from factory unless specifically needed. Iirc it increases it a bit.
 
lms said:
In regards to the selectable input sensitivity, should I try the lower level?
Thx much.
Click to expand...

Where is the volume control on the preamp now, with the attenuators on the amp turned up? If you have to turn the preamp almost all the way up now to get a listenable volume, then using the lower input sensitivity would let you use a lower preamp volume setting. If you can get it loud now with say 50 to 75% on the preamp volume control, then the lower amp sensitivity might limit your preamp volume control to like 0 to 20% usable range - then you are back to turning the attenuators on the amp down.

If it's working OK now and gets loud enough without having to crank the preamp all the way up, you're probably good to go.
 
I like my music pretty loud, listen rock, mostly. With the pots on the crown all the way up, the max I can have the preamp now is half way, so I'm good to go I think. I might turn the pots down on the crown one or two notches and test.
Oh, and the crown I have the sensitivity is adjusted using the menu items, so pretty easy.
Thx.
 
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Sounds to me like you're pretty much in the sweet spot, that's about how I like mine to be as well.

I don't think you'll need to, and I personally wouldn't, but if you decide to experiment with the amp sensitivity setting be sure to turn the preamp all the way down first. It'll be a lot louder for the same preamp setting and you might damage something if you accidentally have the preamp turned up to where it was at the 1.4v setting.
 
Not everyone chooses the same output levels for their pre-amps and not all amps have the same sensitivity. So getting things matched up can be a challenge. Some amps the sensitivity is .5 to ..7 volts and matching pre-amps are designed to operate at the same level. Some amps can require close to 4 volts to reach rated out put so a pre amp rated at .7 volts even with extra head room might not work that well. And pre amps designed to be use at 3 volts with a 10 volt capability wouldn't work well with that amp rated at .7 volts. Most Crowns are in the 1.4 to 1.7 volt range with the controls wide open. You might want to back them off to the 4:00 position if you hear any noise at your listening position. Don't go sticking your ear in your speaker. Odds are there will be noise. As long as you can't hear it where you sit you will be fine. You might want to make sure when no body is home or when everyone is asleep just incase.
 
The Crown manual suggests using the High sensitivity setting (0.775V) when used with components with RCA connections (aka consumer electronics). That's the setting I use and it works fine without any issues.
 
lms said:
...
In regards to the selectable input sensitivity, should I try the lower level?
Thx much.
Click to expand...

No harm in trying. The biggest pitfall could be only that there isn't much resolution in volume adjustment; a little change in position makes a big change in volume.

Far as Crown's recommendation for 0.775, that's lower number/higher sensitivity than usually found in the typical "consumer" SS power amp. I find they tend to be in the 1.2 - 1.7V range for rated output.
 
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I gave it shot and its a no go for me. Like stated, turn the volume on preamp and it increase volume way to much.
 
lms said:
I gave it shot and its a no go for me. Like stated, turn the volume on preamp and it increase volume way to much.
Click to expand...

What are the speakers?

If you've got high sensitivity speakers, that might be part of the issue. I ended up modifying my pre, even though it had a db pad option, it wasn't enough to really use. One notch was too quiet, two was too loud. I replaced the resistors and now 10 notches is what two was before.

Somebody must make db pad rca jumpers, like an fmod?
 
loudnoises said:
What are the speakers?

If you've got high sensitivity speakers, that might be part of the issue. I ended up modifying my pre, even though it had a db pad option, it wasn't enough to really use. One notch was too quiet, two was too loud. I replaced the resistors and now 10 notches is what two was before.

Somebody must make db pad rca jumpers, like an fmod?
Click to expand...

Or just leave the amps on the 1.4v setting.
 
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