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Topic: Brown out from the bull machine |
Brooks Montgomery
From:
Idaho, USA
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Posted 11 Aug 2024 4:14 pm |
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Here’s a new problem (maybe an old problem?) in the wild west:
Yesterday in very rural central Idaho, I sat in with a band at a biker show and barbeque. A typical small-time outdoor band gig…with Harley’s, Triumphs ….and a bull machine. Our stage was a big flat bed trailer under the canopy of a giant weeping willow tree (or whatever the giant shade making thing was).
Next to the ‘stage’ was a bull machine, complete with thick crash pads, and the controller table with the switches and dials for the bull. People lined up and rode the bull while we played.
After the first couple songs, I noticed that my amp was just not clean (Fender Tonemaster Twin w/ Black Box). All of our amps sounded funny, and then we smelt burning, melting, electrical smell: it was the guitar players Peavey Classic 30 tube amp. Then we noticed, every time there was a rider and the bull-machine was going, we got sympathetic interference on the PA and amps with each twist of the bull.
The bull caused a pulsing brown-out. The guitar players amp got smoked.
The power for the stage and the bull machine was coming from an RV park outlet. We ended up running another power cord out from another place, and meanwhile, the guitar player was able to program his Helix pedal board to play (very tastefully) thru the PA. The modeling Helix pedal board saved the day….and honestly sounded better to me because it was spread out and saturated thru the PA speakers and the monitors.
One more thing to be aware of playing out here in the wild west. I gotta think some of you guys are bull machine experienced with your own tales…..
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A banjo, like a pet monkey, seems like a good idea at first. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 12 Aug 2024 4:36 am
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Common 18 gauge extension cables cause severe voltage drops over long distances, and the more power pulled through them the lower the voltage. Thus even if the total load was not enough to pop a breaker the voltage drop could easily toast an amp or other electrical gear. If you look diligently you can find "heavy duty" 16 gauge extension cords but that is not much of an improvement. Note that NEC specifies 14 gauge minimum wire size for 15 amp circuits, the most common 120VAC outlets.
I made up my own power cables with 12/3 SOW cable and a few quad boxes from the local big box hardware outlet, including a stage hod with multiple quad boxes marked "BAND POWER ONLY" and a 150' long feeder for those special venues. We ALWAYS home run our power cables to the source, and all of the gear is on a single ground. With a voltage meter on the amp rack I can keep an eye on things before it becomes a problem.
Sorry to hear about the blown amp, that's no easy fix. |
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Bobby D. Jones
From:
West Virginia, USA
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Posted 12 Aug 2024 1:50 pm
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Good dependable power with proper ground are important for amps and PA systems.
Playing an old community building one night. A light on the stage flickered every now and then.
I plugged my Tube-Fex and power amp into a outlet on the stage. In our first song the light flickered. My Tube-Fex locked up. Had to send it back to Peavy. Cost $90.00 to fix.
We found that a so called electrician had pulled 120 volts off one leg of 240 volts circuit going to a deep fryer in the kitchen near the stage. The thermostat relay was not locking in instant, It was fluttering.
I am with Dave Grafe, I made 1 25ft. 3-12, 4 outlet box, 2 25ft. 3-12, 2 outlet box extension cords. I always take on first time unknown gigs. Bailed our band out several times, On Wedding, Birthday, Christmas party and nursing home gigs. |
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David Ball
From:
North Carolina High Country
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Posted 12 Aug 2024 2:03 pm
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Another 12 gauge drop cord to a quad outlet box user here. Used them for under raised floor 120 service in computer rooms for years.
Most of the stuff I worked with in those days were hard wired 3 phase connections, but we did have the occasional 120 single phase device that needed power...
Dave |
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Jon Jaffe
From:
Austin, Texas
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Posted 12 Aug 2024 4:04 pm
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I feel your pain, Brooks. Brownouts from bulls, whether mechanical or natural, are distressing. Knock on wood; I have not experienced electrical destruction of my equipment. The larger venues I've played at have always had reliable power. For the smaller venues, electrical reliability is inversely proportional to the number of neon signs.
This solution is easier to carry to check circuits than lugging cables.
About $22 retail. |
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Dave Mudgett
From:
Central Pennsylvania and Gallatin, Tennessee
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Posted 12 Aug 2024 10:10 pm
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Up here in the Northeast/Mid-Atlantic, I haven't had to contend with mechanical bulls. I think we got past the Urban Cowboy phase a long time ago, LOL. But an outlet tester as Jon describes is always in my gig bag, and I use it. Anything but correct wiring is a serious electrocution and/or equipment destruction hazard.
I don't play outdoor gigs or a gig with the slightest bit questionable power without my Furman AR-1215 voltage regulator. This is much more than a so-called 'power conditioner' - it corrects both the incoming power voltage and waveform. And if the input voltage is either below or above limits (I believe the lower limit is 90 VAC and the upper limit is 130 VAC), it cannot correct adquately, and thus shuts down the power to the outlets. And yes, it has shut down quite a number of times on outdoor gigs. I insist that they fix the power before proceeding. One time they couldn't - they simply didn't have an adequate power source anywhere - and we didn't play.
For me, these situations are usually smallish, relatively low-volume, outdoor affair where some clown runs a 100-300 foot 16-18 gauge cable from a normal wall outlet inside a restaurant/bar/winery/brewery/whatever to a distant outdoor 'stage' - um, this is never a stage, it's some impromptu thing set up haphazardly. I'm not coming to a situation like this ready to completely circumvent a complete lack of thought about providing any type of reasonable power source. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Aug 2024 2:19 am
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| Jon Jaffe wrote: |
This solution is easier to carry to check circuits than lugging cables. |
Being able to check power only tells you when there is a problem, but it's not a solution. I carry a VOM and there's a voltage monitor on the amp rack, but especially in summer when outdoor stages are some distance from power sources "lugging cables" is still a wise course of action, and the only way to ensure proper voltage and ground to your band's gear. |
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Brooks Montgomery
From:
Idaho, USA
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Posted 13 Aug 2024 4:39 am
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Thanks all for your recommendations. We’ve got a Fair gig coming up where no one seems to know what our power will be. I have a feeling the misadventures might continue.
I suppose the fair will have real bulls without voltage issues.😎
_________________
A banjo, like a pet monkey, seems like a good idea at first. |
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Brooks Montgomery
From:
Idaho, USA
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Posted 13 Aug 2024 5:18 am
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I recently bought a Hughes Power Watchdog 30amp surge and cut off protector for my Airstream trailer. Would that work as a safety surge and cutoff in a band scenario? Expensive little unit….
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A banjo, like a pet monkey, seems like a good idea at first. |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Aug 2024 7:24 am
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| Brooks Montgomery wrote: |
| I recently bought a Hughes Power Watchdog 30amp surge and cut off protector for my Airstream trailer. Would that work as a safety surge and cutoff in a band scenario? Expensive little unit…. |
It would protect from over-voltage surges but not the chronic under-voltage condition that comes from driving a stage with long 16 gauge extension cords, which can kill gear just as dead as a high voltage surge. A complete solution involves filtering noise, the ability to maintain proper voltage when the source is inconsistent, and visual monitoring to let you know what's going on, and this is not inexpensive.
https://www.sweetwater.com/store/detail/P1800AR--furman-p-1800-ar
https://www.grainger.com/product/TRIPP-LITE-Power-Conditioner-20A-5JK12 |
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Brooks Montgomery
From:
Idaho, USA
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Posted 13 Aug 2024 7:35 am
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Thanks again Dave. The power watchdog does shut off under power—it has done it with my trailer, but I’m pretty ignorant about how little or if it is applicable to amps and such.
I will look into the solutions you provided. Thanks mucho amigo.
_________________
A banjo, like a pet monkey, seems like a good idea at first. |
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Jeff Highland
From:
New South Wales, Australia
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Posted 13 Aug 2024 12:03 pm
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How does undervoltage kill a traditional valve amp? given that many techs bring an amp up to voltage on a variac.
Just wondering.
_________________
Duesenberg Fairytale
1949 Supro Supreme
1950 National New Yorker
2008 Highland Baritone Weissenborn
2020 Highland New Yorker.
2020 Highland Mohan Veena
2021 Highland Weissencone |
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Dave Grafe
From:
Hudson River Valley NY
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Posted 13 Aug 2024 6:54 pm
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| Jeff Highland wrote: |
How does undervoltage kill a traditional valve amp? given that many techs bring an amp up to voltage on a variac.
Just wondering. |
When you use the amp at a lower line voltage, the high voltage power supply (B+) and the (12.6 or) 6.3 VAC heater supply will be lowered proportionally. The heater supply specification is typically +/- 10%. Below a certain level, the tubes are going to shut down. This includes tube rectifiers which supply power to the rest of the amp.
When the B+ supply is lower, the output power is going to fall, the power supply caps are not going to fully charge, they will not be able to supply the current that the amp was designed for. The voltages at the tube plates will be lower. The operating point of the tubes is going to shift resulting in compression and then distortion. If the operating point shifts too much the tubes will shut down or partially shut down depending on the input swing of the signal that is feeding them.
A variac is a device that allows you to reduce or boost the line voltage by turning a knob. The variac plugs into the wall, the amp plugs into the variac. Sometime people use these on guitar amps to lower the line voltage. Van Halen for instance used to lower the line voltage to 90 volts on his Marshall 100W amp. At 90VAC, the amp distorted in a good way. Below 90 VAC and the amp lost its sweet sound and farted out. I mention this because dropping from 120 to 90 is 30 volts. Quite a bit. He used to re-bias the power tubes to operate them properly at this voltage. You can't do this if the amp has a tube rectifier.
At a lower line voltage, the character of your amp is going to change. How much so depends on the line voltage drop, the design of the amp, and the specs of the components. In general, the power supply caps and resistors will do fine at a reasonably lower B+ voltage. The amp will operate at a lower line voltage within the specified operating voltage range of the amp. Beyond that, the power tubes are pushed too hard. The higher current draw through the power tubes also stresses the power transformer. This could put a strain on some of the components in the power amp. If the tubes blow, they could take other components and even the output transformer with them.
That's how under-voltage kills valve amps. |
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