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Topic: Distortion in a class D, SSAmp |
Tom Wolverton
From:
Carpinteria, CA
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Posted 21 Jul 2014 11:14 am |
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I played a gig yesterday and my small rig with a 12†BW and an GK MB-200 sounded distorted. I checked everything in the signal chain and could not find the source of the distortion. It was just minor distortion, but it was clearly there. The only thing I did notice was that the power to the location we were playing at came thru a long extension cord. Is it possible that the line loss from this AC cord could drop the voltage going into the GK MB-200 enough that it started to distort? I did not have a meter to check the line. It’s what I finally decided must be happening. I played the gig with sucky tone. Anyone ever have this happen? If I had brought a tube amp (like a Showman), would this have happened?
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To write with a broken pencil is pointless. |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 21 Jul 2014 11:34 am
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Could be low voltage from a long extension cord, although I would think the this would cause a class D amp to sound utterly horrible to not work at all.
Yes, low AC voltage can make a tube amp sound bad. I once played on a barge in the Susquehanna river at a festival in downtown Harrisburg to an audience on-shore. The power was from a very long extension cord, and the nominal voltage was low, I measured it somewhere around 105 VAC. But there also wasn't enough current capacity - every time the bass player hit a strong, sustained note, the voltage dropped even further, to the point where you could hear the guitar amps - there were two old Fenders - just about cut out.
I had dealt with low voltages before, but after this, I got a rack-mountable Furman AR-15 voltage regulator. It gives 12-15 amps of clean power down to something like 90 VAC input voltage, never had a problem since. I take it to most any gig, and certainly any gig where I'm not sure about the power. |
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Robert Parent
From:
Gillette, WY
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Posted 21 Jul 2014 12:51 pm
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| My bet would be on the low voltage..... The early class D amps were very sensitive to low voltage. No idea on your amp design, but very likely. |
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Robert Parent
From:
Gillette, WY
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Posted 21 Jul 2014 12:52 pm
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| My bet would be on the low voltage..... The early class D amps were very sensitive to low voltage. No idea on your amp design, but very likely. |
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