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[Scott Holtzman]

One of my summer concert series had to move locations due to covid. It took a few weeks to get the AC power sorted out. To make a long story short - for the first three shows we powered the mains and front line (4) active monitors from a single 20 amp circuit with a 50 foot 12 gauge  cable. We then ran another 100 feet from that same circuit to FOH - 150 feet total.
FOH was a QU24, MAXXBCL, Tascam USB/SD media player which were plugged into a Furman M-8X AR 15A Voltage Regulator.
The input meter on the Furman was showing as low as 105VAC input voltage. Never had a problem with any of the FOH gear. The Furman was able to maintain a stable 120VAC to power the FOH equipment.

That Furman is an interesting device and it is not cheap.  At first I thought it was an autoformer however I don't think you could get one of those in 1U.  Then I saw the specs claim 8 taps on the toroidal transformer.  Now we are getting somewhere.  Maybe 4 taps are buck and 4 are boost?  Some type of real time switch can select from the 16 combinations of windings to achieve the voltage regulation?  Does anyone know how this actually works?

[Steve-White]

^^^ For 1800W they could probably fit a toroid coil inside it without too much grease.

https://www.furmanpower.com/product/merit-series-15-amp-voltage-regulator/

[Geoff Doane]

Maybe 4 taps are buck and 4 are boost?  Some type of real time switch can select from the 16 combinations of windings to achieve the voltage regulation?  Does anyone know how this actually works?

That's how the original version of this (AR-115?) from 30 years ago worked.  They engineered zero crossing switching into it when it changed taps, so it was pretty seamless.  It does have the disadvantage of drawing even more current when it's boosting the voltage, perhaps making the voltage drop even worse.

I have a fair bit of experience with double-conversion UPSs in studio and mobile recording situations, and they all have the problem that they have fans running all the time, so generate quite a lot of acoustic noise.  We could only use them when an isolated machine room was available, so plunking one next to your console in a quiet concert hall will not be an option.  They also don't work well as the only load on a generator.  They draw a lot of current when charging, which causes the generator to slow down, which causes the UPS to switch to battery, which causes the generator to speed up...

The fix was to have about half the load not on UPS.  In the mobile that could be the HVAC and non-critical systems, and that damped the speed fluctuation enough that the UPS was happy.  In the setup I looked after, we had a 12 KW Onan diesel generator, and two 3 KVA Eaton UPSs, each loaded to about 40 or 50%.  The HVAC and lighting load was typically about 3 KW as well.  But trying to run just the two UPSs off the generator by themselves was asking for trouble. 

GTD

[Ned Ward]

Our marching band has a Cyber Power PR2200LCDRT2U UPS unit to protect the TF5 mixer.

Last Saturday was a double whammy - power at Huntingon Beach HS failed, and our generator (Champion 100158R) decided to stop working (engine ran, GFCI outlet kept tripping). Ran the 8 minute show on just the Cyber Power UPS.

Besides the Yamaha TF5, also had these speakers also on the unit:
EV ETX-35P x 2
EV ETX-18SP x 2

Worked fine. Getting the generator checked/tuned up to understand what's tripping the GFCI - I suspect crappy old low gauge 100' Home Depot extension cables that may have shorts, too low a gauge, too long, or a mix or all those.

[Brian Jojade]

That's how the original version of this (AR-115?) from 30 years ago worked.  They engineered zero crossing switching into it when it changed taps, so it was pretty seamless.  It does have the disadvantage of drawing even more current when it's boosting the voltage, perhaps making the voltage drop even worse.

Any voltage regulator is going to have that problem. If you're increasing final stage voltage, you're going to pull more current from the lower voltage segment. There are no free watts.  The exception being with variable current draw devices that can store power within, recharging when power isn't being needed.  That's a different beast though.

[Tracy Garner]

Our marching band has a Cyber Power PR2200LCDRT2U UPS unit to protect the TF5 mixer.

Last Saturday was a double whammy - power at Huntingon Beach HS failed, and our generator (Champion 100158R) decided to stop working (engine ran, GFCI outlet kept tripping). Ran the 8 minute show on just the Cyber Power UPS.

Besides the Yamaha TF5, also had these speakers also on the unit:
EV ETX-35P x 2
EV ETX-18SP x 2

Worked fine. Getting the generator checked/tuned up to understand what's tripping the GFCI - I suspect crappy old low gauge 100' Home Depot extension cables that may have shorts, too low a gauge, too long, or a mix or all those.

This is awesome info. The only thing I need to protect is an external powered hard drive and a Behringer X-32. As long as I have the AVR, it should work for what I need. The X-32 would only reboot on really hard peaks on the generator. This makes me believe the battery would have time to recover.

[boburtz]

This is awesome info. The only thing I need to protect is an external powered hard drive and a Behringer X-32. As long as I have the AVR, it should work for what I need. The X-32 would only reboot on really hard peaks on the generator. This makes me believe the battery would have time to recover.

We installed regular ol' Cyberpower PR500cdrt1u into our console cases, just to run the console in case of a power interruption, thinking this would save us from the headache of a reboot in a short power loss. What we found was, they do not like generator power. Any deviation in the ac supply would cause them to go into battery mode, even if briefly (~10 seconds at a time). This was happening so often that it would deplete the battery and then possibly shut down completely. It happened every time we used generators as our power source, and these were multiple different rented multiquip whisperwatt (or equivalent) high power diesel units. I'm sure a double conversion system would avoid this, as they operate as regulators, not just battery backups. We removed them from our console cases and no longer use them in production. My experience is that they cause more headaches than they solve. I would advise double-conversion regulators or nothing.

[Steve-White]

We installed regular ol' Cyberpower PR500cdrt1u into our console cases, just to run the console in case of a power interruption, thinking this would save us from the headache of a reboot in a short power loss. What we found was, they do not like generator power. Any deviation in the ac supply would cause them to go into battery mode, even if briefly (~10 seconds at a time). This was happening so often that it would deplete the battery and then possibly shut down completely. It happened every time we used generators as our power source, and these were multiple different rented multiquip whisperwatt (or equivalent) high power diesel units. I'm sure a double conversion system would avoid this, as they operate as regulators, not just battery backups. We removed them from our console cases and no longer use them in production. My experience is that they cause more headaches than they solve. I would advise double-conversion regulators or nothing.

No snobbery intended here - but, a $350 solution to a $1000 problem could be what went wrong.  I run multiple tower UPS's on generator without issues - haven't tried a 1U or 2U Rack Mount yet.  What it takes is being able to adjust the power quality sensing in the input of the UPS and decent generator power.  You probably had pretty decent power, but low end UPS's.  Learning how to do it took some testing, upgrading generators and testing.

Testing is your friend.  However, if renting generators testing could get expensive and may not be worth it.  I own my generators. 

[boburtz]

No snobbery intended here - but, a $350 solution to a $1000 problem could be what went wrong.  I run multiple tower UPS's on generator without issues - haven't tried a 1U or 2U Rack Mount yet.  What it takes is being able to adjust the power quality sensing in the input of the UPS and decent generator power.  You probably had pretty decent power, but low end UPS's.  Learning how to do it took some testing, upgrading generators and testing.

Testing is your friend.  However, if renting generators testing could get expensive and may not be worth it.  I own my generators. 

You are correct that these were consumer level ups units. We were trying to solve the Yamaha USB drive recording from being corrupted by a power interruption. Our solution was to use a relay feeding the gpi and the UPS being the failsafe. These inexpensive units were not the solution, thus my advocacy for double conversion units. In our situation, they needed to be rackmounted for ease of setup and portability, as they were installed in a rackspace beneath the console inside the road case, and always connected to the gpi. We are a mobile company, so we get generators of multiple sizes (from Honda EU6500 to multiquip 160kva and higher, depending on the necessity) from multiple vendors. The cheap UPS units didn't like any of them. Ultimately, we decided it was more of a headache than it was worth, and scrapped the idea of an onboard UPS. We may revisit once business gets back to full swing, but will be using double conversion for the next experiment.

[Steve-White]

^^^ Look for UPS's that you can adjust the power quality sensing on the line input and you'll be set bro.

I went through several UPS's and about /12 dozen generators getting things sorted out and learning.  Glad I did now, but it was frustrating.

[ProSoundWeb Community]