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[Geoff Doane]

Indeed. Most of the Furmans units use MOVs the same thing that's an any home grade $20 power strip. You are getting shafted if you are buying these. They don't protect anything very well.

I think you and Thomas are being a little bit harsh about the Furmans here.

It's true that their ability to "clean up" dirty power (whatever that is) may be suspect, but they do give you some indication of what the line voltage is.  Even if the absolute accuracy is not that great, it will tell you if the voltage is sagging on the kick drum hits, or if it goes high when the club's air conditioner kicks in on one of the other phases (yes, I've seen both).  It's a whole lot better than a regular power bar because it's mounted in the rack, and it's always there, not something you have to remember to plug in.

And even if MOVs are not the best protection technology, they do work when those gross overvoltage situations happen.  Just last month, on a gig I was supplying gear for, the bass player arrived first, and plugged his powerbar (not a Furman) into the quad box the event company had put out on the stage.  There was a brief BANG, and the powerbar sacrificed itself.  My tech on site pulled out his voltmeter, and measured 213V on one duplex and 112 on the other.  Classic case of somebody mixing up a neutral and hot when they replaced an L14-20 plug.  (The event company was quite unapologetic. "It's not like we were charging you for the powerdrop.")

Even when the power has been metered first, things can go south in a hurry.  A number of years ago with another rig, the neutral fell off at the tie-in point (connected by the house electrician, but obviously not torqued down tight enough.  I suspect it was cross-threaded.).  The feed to FOH went high, but everything in the rack was plugged into a PL-Plus, and it clamped the voltage to something tolerable, resulting in no damage to the rack equipment.  The console, which was not on the load side of the Furman, suffered a failed bridge rectifier in the PSU (possibly an under spec'd part to start with), and had to be replaced before showtime.  I don't recall if the breaker in the Furman tripped or not, but the bottom line is, most of the equipment was undamaged, and the failed gear was fairly easy to fix.

The only downside I can see is that the MOVs can become leaky, and actually inject noise into the ground of your system.  Many people clip them out for this reason, but replacement would make more sense, since they are giving you some measure of protection from unpredictable power.

Of course they can't do anything about brownouts or any noise that is on the line.  For that, a double-conversion UPS is really the only solution, but as has already been mentioned, it's just not practical to power your amplifiers from that.

GTD

[TJ (Tom) Cornish]

; "power conditioners" unless built by SurgEx, don't really condition anything

To be completely correct, SurgEx devices don't "condition" anything either - they are a higher-quality surge suppressor that clamps at a lower voltage than MOVs, and do so in a non-sacrificial manner.  They are the best surge protectors on the market, however they don't fix bad power.

As Geoff mentioned, truly conditioning the power - changing whatever garbage arrives into a clean sine wave - requires a double conversion UPS - one that uses line power to charge the battery, and the load is always run from the inverter.

[Tim McCulloch]

I think you and Thomas are being a little bit harsh about the Furmans here.

It's true that their ability to "clean up" dirty power (whatever that is) may be suspect, but they do give you some indication of what the line voltage is.  Even if the absolute accuracy is not that great, it will tell you if the voltage is sagging on the kick drum hits, or if it goes high when the club's air conditioner kicks in on one of the other phases (yes, I've seen both).  It's a whole lot better than a regular power bar because it's mounted in the rack, and it's always there, not something you have to remember to plug in.

And even if MOVs are not the best protection technology, they do work when those gross overvoltage situations happen.  Just last month, on a gig I was supplying gear for, the bass player arrived first, and plugged his powerbar (not a Furman) into the quad box the event company had put out on the stage.  There was a brief BANG, and the powerbar sacrificed itself.  My tech on site pulled out his voltmeter, and measured 213V on one duplex and 112 on the other.  Classic case of somebody mixing up a neutral and hot when they replaced an L14-20 plug.  (The event company was quite unapologetic. "It's not like we were charging you for the powerdrop.")

Even when the power has been metered first, things can go south in a hurry.  A number of years ago with another rig, the neutral fell off at the tie-in point (connected by the house electrician, but obviously not torqued down tight enough.  I suspect it was cross-threaded.).  The feed to FOH went high, but everything in the rack was plugged into a PL-Plus, and it clamped the voltage to something tolerable, resulting in no damage to the rack equipment.  The console, which was not on the load side of the Furman, suffered a failed bridge rectifier in the PSU (possibly an under spec'd part to start with), and had to be replaced before showtime.  I don't recall if the breaker in the Furman tripped or not, but the bottom line is, most of the equipment was undamaged, and the failed gear was fairly easy to fix.

The only downside I can see is that the MOVs can become leaky, and actually inject noise into the ground of your system.  Many people clip them out for this reason, but replacement would make more sense, since they are giving you some measure of protection from unpredictable power.

Of course they can't do anything about brownouts or any noise that is on the line.  For that, a double-conversion UPS is really the only solution, but as has already been mentioned, it's just not practical to power your amplifiers from that.

GTD

And the Furman and similar units will fail sooner or later when used to power up an amp rack of any significant capacity.

I have no problem with using them or their ilk on lower current draw items that need or benefit from such protection, but PA system power amps do not need them.

[Tim McCulloch]

To be completely correct, SurgEx devices don't "condition" anything either - they are a higher-quality surge suppressor that clamps at a lower voltage than MOVs, and do so in a non-sacrificial manner.  They are the best surge protectors on the market, however they don't fix bad power.

As Geoff mentioned, truly conditioning the power - changing whatever garbage arrives into a clean sine wave - requires a double conversion UPS - one that uses line power to charge the battery, and the load is always run from the inverter.

fixed it

[TJ (Tom) Cornish]

I think you and Thomas are being a little bit harsh about the Furmans here.

It's true that their ability to "clean up" dirty power (whatever that is) may be suspect, but they do give you some indication of what the line voltage is.  Even if the absolute accuracy is not that great, it will tell you if the voltage is sagging on the kick drum hits, or if it goes high when the club's air conditioner kicks in on one of the other phases (yes, I've seen both).  It's a whole lot better than a regular power bar because it's mounted in the rack, and it's always there, not something you have to remember to plug in.

And even if MOVs are not the best protection technology, they do work when those gross overvoltage situations happen.  Just last month, on a gig I was supplying gear for, the bass player arrived first, and plugged his powerbar (not a Furman) into the quad box the event company had put out on the stage.  There was a brief BANG, and the powerbar sacrificed itself.  My tech on site pulled out his voltmeter, and measured 213V on one duplex and 112 on the other.  Classic case of somebody mixing up a neutral and hot when they replaced an L14-20 plug.  (The event company was quite unapologetic. "It's not like we were charging you for the powerdrop.")

Even when the power has been metered first, things can go south in a hurry.  A number of years ago with another rig, the neutral fell off at the tie-in point (connected by the house electrician, but obviously not torqued down tight enough.  I suspect it was cross-threaded.).  The feed to FOH went high, but everything in the rack was plugged into a PL-Plus, and it clamped the voltage to something tolerable, resulting in no damage to the rack equipment.  The console, which was not on the load side of the Furman, suffered a failed bridge rectifier in the PSU (possibly an under spec'd part to start with), and had to be replaced before showtime.  I don't recall if the breaker in the Furman tripped or not, but the bottom line is, most of the equipment was undamaged, and the failed gear was fairly easy to fix.

The only downside I can see is that the MOVs can become leaky, and actually inject noise into the ground of your system.  Many people clip them out for this reason, but replacement would make more sense, since they are giving you some measure of protection from unpredictable power.

Of course they can't do anything about brownouts or any noise that is on the line.  For that, a double-conversion UPS is really the only solution, but as has already been mentioned, it's just not practical to power your amplifiers from that.

GTD

Some Furmans have over-voltage shutdown, and that is indeed valuable.

Expanding on what you are saying about lost neutrals, the neutral wire will always be "pulled" towards the leg with the most load - amps or lighting.  This will result in an under-voltage configuration, something that a "power conditioner" will not be able to help - another reason why they are of limited value on high-current devices.  In FOH racks, a device with over-voltage shutdown is a good thing.

[jasonfinnigan]

True that none of these really offer conditioning but they do offer protection which can always be valuable, espcially if you are running on a generator. Though some of them anymore do a pretty good job on there own on the nice once that we have rented. they've come a long way.

To get true conditioning you would need a UPS but it's very impracticable my other job is a Network Administrator and  I can tell you would not want to lug these around. for one the space it takes up, your looking at multiple racks full of UPS power. Not to mention these can be very dangerous they can explode easily it usually take a cord somehow getting losing in the UPS or the battery units and shorting out - but that just siting in racks in a data center think of touring on the road with something like that, they would get beat around all the time. Not a good idea.

I also don't think you usually need a conditioner on power amps. Class D amps yeah they probably would, but a rack of amps are a lot more tolerable to power fluctuation than a class D amp or a digital console (granted your output power might suffer some on the amps).

[TJ (Tom) Cornish]

Class D amps yeah they probably would?

Why do you think so?  Many class D amps have universal power supplies and can accept 100-240 volts.  The better ones have power factor correction, meaning they can function on much weaker supplies than conventional amps.

[Russ Davis]

I have no problem with using them or their ilk on lower current draw items that need or benefit from such protection, but PA system power amps do not need them.

I've always adhered to that philosophy, but... how does one protect the DSP on amps so equipped?

[TJ (Tom) Cornish]

I've always adhered to that philosophy, but... how does one protect the DSP on amps so equipped?

Why do you assume the DSP needs protection?  Amp designers know what they are making - a DSP engine that has to survive strapped to a rocket ship that sucks the mains voltage down to 100 volts on heavy peaks, etc. 

[jasonfinnigan]

I've always adhered to that philosophy, but... how does one protect the DSP on amps so equipped?

Most power supply's do their own filtering of some sort using Capacitors and etc. While I'm sure it *Could* be damaged the likely hood of that being damaged without the whole thing going down is low. I would assume most of the engineers know more than us when building a power circuit.

[ProSoundWeb Community]