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Topic: Input controls on Stewart power amp |
Ron Sodos
From:
San Antonio, Texas USA
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Posted 5 Oct 2011 3:24 pm |
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I have a couple of Stewart PA100b power amps that I recently replaced. I notice that when the recessed O/L level controls are turned up the speakers clip real bad. I can reduce the level and remove the clipping but the volume seems reduced considerably. Anybody experienced this issue. Does it imply a problem with the amp or am I just trying to overdrive the amp and need to keep the level turned down to reduce the distortion???
Ron Sodos
Albuquerque NM |
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 5 Oct 2011 7:13 pm
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| I've used Stewart power amps for years and still use one on occasion. I've never had that issue but it sounds to me like the preamp signal may be too high. The power amp is just going to amplify the signal going to it. Not sure what you're using in front of the Stewart, but I would check that first. Second may be a speaker issue. If those fail then the amp may be an issue. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 5 Oct 2011 8:53 pm
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When the amp clips it has essentially used up all the electricity its power supply can produce. When the speaker clips it has exceeded its maximum cone travel. As the amp you are using only produces 50w per side into 8 ohms it is unlikely that you are overdriving the speakers but highly likely that you are not getting the power that you need to cut through a full electric band without pushing the rig into clipping somewhere along the signal chain.
By reducing the gain of the pre-amp or the amp itself you eliminate the clipping, the trick is to identify which element is maxed out. Ideally, your amp should be set to clip just above the pre-amp's max (clipping) level, and your speakers should be rated to handle the resulting max power. Bear in mind that 20 or 30 watts of badly clipped signal can destroy a 100 watt speaker if you keep it up long enough. Here is a quick-and-dirty way to calibrate your rig.
1) set your amp volume controls at 12 noon (1/2 full) and play through the rig with your VP full on, turning up the pre-amp slowly until you hear it begin to distort unacceptably - a little growl is a great thing but as soon as the sound becomes unmusical turn it down a wee bit and make a note of that level position.
2) with the pre-amp set thusly, continue playing and begin to turn the amp levels up slowly, again listening for unmusical distortion. When you reach this clipping point make a note of the amp's level settings. Your rig is now calibrated for maximum headroom, if it is not loud enough when set thusly it is time for you to find a bigger power amp or more efficient speakers. |
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Ken Metcalf
From:
San Antonio Texas USA
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Posted 6 Oct 2011 2:42 am
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When I was sorting out my rack system.....by the end I found that I needed a world 1.2 to achieve the sound I was after.
I sought out professional electric sound help with minimal results.
Can't believe it would take so many watts to drive a system like this.
But little combo amps can run on much less.
_________________
MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes |
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Buddy Castleberry
From:
HAWKINSVILLE GA USA - R.I.P.
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Posted 7 Oct 2011 10:49 am
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the o/l level is the output levels not input levels
i run those full open .i start with the preamp volume
then the gain a little higher then my mpx1 a little higher with the stewart being the highest
clean as a bell |
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Buddy Castleberry
From:
HAWKINSVILLE GA USA - R.I.P.
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Posted 7 Oct 2011 10:50 am
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the o/l level is the output levels not input levels
i run those full open .i start with the preamp volume
then the gain a little higher then my mpx1 a little higher with the stewart being the highest
clean as a bell |
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Ken Metcalf
From:
San Antonio Texas USA
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Posted 8 Oct 2011 3:31 pm
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I guess I should say that I also run the power amp pretty much wide open and the the distortion I got was from cranking up the pre-amp section not the Stewart.
No problems with the Stewart World 1.2
It seems to be plenty loud and clean with exceptional sound.
_________________
MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes |
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