Amp not getting enough voltage?...What's going on?

George Kimery · From: Limestone, TN, USA

I played a gig Saturday night and took my Session 500 out for the first time. I had to turn the pre and post gains all the way up and push the volume pedal half way down to get enough volume to play. Also, the quality of the sound was just not there. I have played my 112 there for 2 years without a problem. My brother could only get minimum volume out of his bass amp on a previous gig in the same building, but the amp has never had any problems anywhere else and worked fine Saturday night. My 500 worked perfect when I brought it home. The stage outlet that I was plugged into had one of those 6 outlet boxes mounted to it. The only other thing plugged in was a string of lights. The building did have 3 110v. portable air conditioners running. On stage, we had a PA and a guitar amp plugged into other outlets as well as the bass amp and the 500. I suspect, but don't know, that everything on the stage is on the same circuit. I did all the normal checks for problems. Tried different cords, took the RV-3 out of the chain, hooked up a different volume pedal, plugged straight from the guitar into the amp, which gave more volume, but still not what it should have.

I tried the guitar player's 85 watt amp and it worked OK. There was definately something going on with the amp, but only in that building. I will be back there on Saturday and will try running a 15 ft., 14 gauge extension cord to another outlet on the front of the stage to see if that will help. Anybody else had a problem like this and can it be that the circuits were just overloaded and I just wasn't getting enough "juice" to it?

Earl Blake · From: Minnesota, USA

I had the same thing happen in June. My Nashville 1000 was fine for sound check. Then when the band kicked in, The amp started cutting out. We changed to a different circuit and it was fine. Then everyone could hear my mediocre playing. Earl

Erv Niehaus · From: Litchfield, MN, USA

I think the above situation is a good reason to have a power strip w/voltage regulator part of your setup. I have a Furman high end unit in my rack and it analyzes the current when I turn it on and adjusts it accordingly if it is off. If the current is too far off, it shuts things down.

Jim Bates · From: Alvin, Texas, USA

George, I had the exact same symptoms on my Session 500 at an old hall in west Houston a few years ago. During warm-up and tuning my amp sounded great and stayed that way for about an hour, and we were really playing loud. I was taking a solo break when my amp just turned into a mushy sound with low volume. We were close to break time, I felt the amp and it was very hot so I turned it off during the break. After break, turned it back on and it was fine for about 30 minutes, then it turned to mush again. I had the biggest and oldest amp in the group so mine was the only one affected. Some of the band had played that hall before and said that amps had problems with the bad voltage there - mine was one.

I described to a local repairman and he said it was classic problems from low voltage and the overheating caused some thermal limiters to kick in which kept the amp from self destructing (his words).

The amp has been fine at other places since and no problems.

A final note for the 'old' hall I mentioned above, it burned to the ground two weeks after we played. Cause was bad wiring. (it was the old Bill Mraz hall for you Houstonians)

Thanx.
Jim

Mike Brown · From: Meridian, Mississippi USA

Sounds like a line voltage problem to me.

John Billings · From: Ohio, USA

Plugging into other outlets doe not always mean plugging into a different circuit. I have 4 outlets in my kitchen, but they're all on the same circuit, and breaker. I played a club where the voltage turned out to be 87VAC! My '56 Pro Amp sounded terrible.
In my studio at home, I have a Furman Balance Transformer.
http://www.worthpoint.com/worthopedia/furman-1220-balanced-ac-low-noise-79632360

chris ivey · From: california (deceased)

maybe mike can shed some light on this:
i played a backyard party where my nash400 had a weak and fuzzed out tone. i went home and got my ltd400 and it was fine.

the nashville has been affected that way before but is normally fine with good power source. why is the ltd not as sensitive?

Mike Brown · From: Meridian, Mississippi USA

Could be a couple of things. Call me at 1-877-732-8391, ext.1180 Monday through Friday CST. Thanks.

George Kimery · From: Limestone, TN, USA

The 500 was not even usable Saturday night in the same venue that I played the previous Saturday night. This time, I still could not get much volume but worse....it was distorted like a fuzz box. Plugged in my 112 and no problems. I checked the voltage and it was 115.6. I came home, plugged the 500 in, and it worked perfect as it always has at home. I checked the voltage at home and it was 123.7. So, the culprit looks like low voltage, although it seems to me that as long as you get 110 volts, minimum, the amp should work OK. I even ran a 50 ft. 16 ga. extension cord to another part of the building, and checked the voltage on the extension. It as the same. 115.6

I am not taking the 500 back to the gig. I have just decided that the 500 watt amp is just too much for the outputs of the electric outlets in the building.

John Billings · From: Ohio, USA

Hmmmmm,,, you might check the voltage when the band is playing.

George Kimery · From: Limestone, TN, USA

John, when I checked the voltage, I was the only one on stage. There were two other amps and the PA plugged in, but they were all turned off. The amp was distorted and it was the only amp turned on. I didn't see any point in checking the voltage while the whole band was playing. I don't think the voltage would have increased. Also, on my original post, I said there were 3 110 volt window air conditioners running. I was in error. I checked Saturday night and they were all 220 volt units.

John Billings · From: Ohio, USA

George,
Didn't realize that. Sometimes things can go haywire when the band are all fired up. Specially the bass player.

Rich Santucci · From: Perkasie Pennsylvania USA

George,

It just seems like such a weird problem.

Do you have a tech that can put this amp on a Variac and raise and lower the AC voltage to it while running a signal thru?

Its just one way of checking power supply regulation.

Rich

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