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Subway and generator fail

gln1955

gln1955

Supporting Member
Aug 25, 2014
12,878
61,882
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Ohio, USA
#1
The story begins back in April. The band has a gig at a public park with no electricity. This is our first time supplying our own power. I'm aware of possible issues with non-inverter type generators, so I offer to bring my Honda, although I'm not sure it would be powerful enough for the whole band. The BL says he is all set up with a brand new generator, so I leave mine at home. I get there and it's not an inverter-type unit. I'm not pleased and tell him the first sign of trouble and I'm literally pulling the plug. Well, everything is fine and we play a four-hour gig without issue.

Chapter 2, we play the same site this week and my D-800 won't power up. Absolutely nothing. I play the gig through a preamp pedal to FOH (which is a miserable experience without adequate monitors) and I'm worried the whole time about a possibly damaged amp. Then I get home and plug the amp in and it's perfectly fine. Dodged a bullet, thanks to some protection circuit, I assume.

I won't be using that generator again, but I'm curious about what exactly happened this time, that didn't happen back in April. The only difference was the gig in April was in about 50F weather and Friday it is was about 90F. Could the high heat cause the amp and/or the generator to behave differently enough to cause the fail?

Calling @agedhorse
 
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#4
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#5
The Subway amps have under and over-voltage protection circuitry which will prevent power-up in the event of an out of limits power condition.

It’s not uncommon for budget generators (and poorly maintained generators) to fail to provide stable, undistorted power.
 
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#7
WayneP said:
For those of us clueless, what affect does a non-inverted generator have on electronics? Looked it up and all I could find is that inverter-types don’t ramp up more than needed, and they are quieter.

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An inverter converts the AC from the generator to DC and then back to AC. The way this is done results in a high quality output that is cleaner and more stable. Inverters are more expensive than regular generators with the same capacity. Also the amount of power they can provide tends to be relatively small.

Inverter generators typically have an Eco mode, which is intended to save fuel by running the engine at the lowest possible RPM required to meet load requirements. Since music is dynamic, the current and power requirements for a big PA tend to change constantly. The motor cannot respond quickly enough to cover the required transients, so Eco mode should not be used for live music support.

With a cheap non-inverter generator the motor is typically controlled by a mechanical governor. The engine runs at the specified speed and the line frequency = 60hz. If load is dynamic, the line frequency and voltage will vary. Also particularly with cheap inverters, I think the waveform of the output can be distorted/dirty.

Non-inverter generators are used for power production all the time. But the quality of commercial inverters is much higher than a cheap personal generator you buy at a big box store. Also the power grid uses banks of generators to feed lots of different users rather than one user with an extremely dynamic power requirement.

If it gets hot, everyone tends to turn on their air conditioner (AC). But they don't typically all turn on their ACs at exactly the same time. The transient caused by one customer turning on one AC is pretty much an inconsequential blip for a huge bank of generators. As more power is required, more generators are brought online.

I have done several gigs on commercial grade generators that were properly connected with no problems. I also remember a gig we were supposed to do where the event coordinator cheaped out on the generators. Not enough capacity and the generators and power distribution were not properly connected. This resulted in bad power and was probably extremely dangerous. We did not do this gig and I believe another band that did was not able to complete their show and their equipment was damaged.

I have done a few gigs on small personal generators without problems. As long as the generator has plenty of excess capacity and provides a reasonably clean and stable output it can work. But it's a good idea to use a quality generator rather than the cheapest unit you can find.
 
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#8
Total tangent, but I saw dirty dozen brass band play through a generator failure at an outdoor show in Portland in the 90s. They just marched into the audience and paraded through the aisles. Good time to have a sousaphone bass! Fortunately the power came back before the Nevilles came on for their headliner set.
 
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#9
Pings Bass said:
Total tangent, but I saw dirty dozen brass band play through a generator failure at an outdoor show in Portland in the 90s. They just marched into the audience and paraded through the aisles. Good time to have a sousaphone bass! Fortunately the power came back before the Nevilles came on for their headliner set.
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I worked with the Dirty Dozen many times, great shows.
 
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#11
Along with my real tools and a Fluke, I always have one of these, and a plug-in outlet tester with me and plugged in behind my rig. It's not lab grade stuff, but it's been plenty reliable and has showed issues BEFORE i plugged in my gear, and not just with generators.
61k+RBieqZL._SL1500_.jpg


Available here:
https://www.amazon.com/gp/product/B08HHYG2Y3/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

voltage-tester-400-029-4f_100.jpg

Available almost anywhere, here's a Home Depot link:
https://www.homedepot.com/p/Recepta...3e55b6e16a6948a079ecabb56fe&gclsrc=ds#overlay
 
As an Amazon Associate, TalkBass may receive commissions from qualifying purchases made via links on this site.
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#12
I had one generator show in the early ‘70s and vowed never to do that again.
The noisy, smelly little b******* behind us dominating the sound system. It sent an incessant buzz through the amps also and every time I attacked a note the volume went down instead of up, followed by the governor ramping up the RPMs of the motor.
Was actually glad when someone in the crowd got stabbed ending the show earlier than planned.
Never thought about amps being damaged, but it was the worst sounding gig I can remember back in the prehistoric past.
 
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#13
I played a gig outdoors recently with a generator that used a battery for powering the unit. I hadn't seen one like this before. We weren't using a huge amount of power but it worked great and made no noise at all, a big plus. Apparently they're quite pricey but really nice. It would automatically be an inverter type and I heard no noise on the line at all and had no other issues that I'm aware of using two amps and a medium-size PA. I don't know the size of the battery but the unit was quite small.
 
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#18
kesslari said:
Anyone have a potential answer to the OP's question "but I'm curious about what exactly happened this time, that didn't happen back in April."
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I think Andy @agedhorse answered it in the most likely scenario, which is that the power the second time around was dirty, and the subway kicked in to shut itself down as it supposed to.
 
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#19
bherman said:
I think Andy @agedhorse answered it in the most likely scenario, which is that the power the second time around was dirty, and the subway kicked in to shut itself down as it supposed to.
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Yes, small inexpensive generators are generally inconsistent with regards to power quality, the THD, regulation and noise vary greatly with load, so there's nothing precision about then the protection threshold may be crossed.
 
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#20
bherman said:
I think Andy @agedhorse answered it in the most likely scenario, which is that the power the second time around was dirty, and the subway kicked in to shut itself down as it supposed to.
Click to expand...

But it worked in April with the exact same generator and loads. Only real difference was the ambient temp. S*** happens, I guess.
 

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