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Power "conditioning" question: power cords...


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Posted (edited)

I'm playing the same venue I did last year when my amp crapped out. When in for the "tech" rehearsal tonight, and my amp was sounding like crap. It might be because the repair job wasn't great--and they replaced my winged C tubes with JJs (blechh, but the tech said my power tubes were what caused the blow out last time). 

Tonight, the amp (Hot Rod Deluxe) had very very very mild distortion at a low low volume, did not sound right. To get power to it, the venue tech had two power strips strung to an extension cable to god knows where behind the stage. But I could see AC outlets about 20 feet from me behind the curtain, so I'm thinking I should get a good power cord and plug in there.

Are there special power extension cords for pro audio that don't hurt the sound (something where you don't need a pricey "power conditioner")?? 

I remember when we used a 100 ft cable in high school to get my amp out with the marching band on Friday nights, and it sounded like crap. What can I do to avoid that??

 

 

Seems like something RedEl34 might know.

Edited by arcadesonfire
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I just did some research and found people saying TAD brand 6L6s are the best replacement for the Svetlana winged C's. So I've got an order on the way from Jeff Bezos. Will put the JJs away for backup. 

Levis stopped making my 513s. SED stopped making the winged C tubes. 

Why, why why why, must things change like this??

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A good test would be to run a thick gauge extension cord to that outlet 20 feet away. 

I have been in clubs where it seemed like somebody's unqualified brother in law did the electrical wiring for the owner.

One thing to beware of is ground loop hum from having gear plugged into different outlets on different circuits.

And the dreaded RFI interference hum from fluorescent lights as well.

Lastly, a power conditioner is cheaper than repair work.

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Extension cords need to be thick enough to handle the load that is plugged into them, and the longer the cord, the thicker the wire gauge in the cord needs to be.

Make sure the extension cable that you buy uses heavy duty wire - a lower AWG number means a thicker conductor. IOW, 12 AWG is better than 14 AWG, although anything better than 14 AWG should handle your amp just fine since a 50' or shorter 14 AWG cable can handle ~15 amps. A 50' or shorter 12 AWG cable should be able to handle ~20 amps. 

If they have too much stuff plugged into a cable that is too long and that uses a thin wire gauge, it's a fire hazard. :cop: 

Oh, while you're at it, you should also get a AC outlet tester - that will tell you if the outlets at the venue are wired correctly or not. If they're not, it could be a potential hazard to your gear and to your health... 

https://www.homedepot.com/p/Commercial-Electric-Outlet-Tester-with-GFCI-OTG-102R/206029151

FWIW, I agree with Tom - a power conditioner is cheaper than amp repairs. 

 

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Posted (edited)

Hmmm... Does a power conditioner need to go near the a/c outlet? Or can i plug the cord into the outlet and then put the conditioner near me?? (I.e., does the conditioner “fix” problems introduced by extension cord?) And I just need two plugs: my amp and my voodoo lab pedal power supply.

At any rate, at first last night, the venue tech had me plug into the same funky OLD two-outlet “strip” as last time, and it had a very thin cord. Sounded terrible—and I wonder if that thing related to my amp dying last year. So I unplugged from that and used my strip (with heavy duty cord) into a decent strip that was plugged into “god knows where.”

I’m going to GC today and could go to Home Depot before the show. I’ll make this work. Thanks for the advice!

Edited by arcadesonfire
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Not intending to hijack the thread, but there's an amusing story from the documentary, "Miracles out of Nowhere", the story of the band, Kansas.  They had a gig where they opened for Aerosmith.  Somebody, knowing that Kansas had been quite successful, warned Kansas about Steven Tyler's practice of unplugging an opening act if he thought they were getting too much positive attention.  Kansas came up with an alternative plan.  They plugged a bunch of cords into some outlets near the stage, but the cords just went towards the equipment and didn't serve any of the amps.  They found other outlets and as secretly as they could, ran the cords to their amps.  When Tyler started his little venture, nothing happened and Kansas continued playing to huge crowd reaction.  Tyler went into meltdown about it.  

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26 minutes ago, arcadesonfire said:

Hmmm... Does a power conditioner need to go near the a/c outlet?

 Not necessarily - you can use an extension cord as long as it is beefy enough. Again, just make sure that there isn't a bunch of other stuff plugged into the same electrical circuit - which isn't always obvious since multiple AC outlets in a building can share the same circuit.* 

 

Quote

I.e., does the conditioner “fix” problems introduced by extension cord?

No. If the extension cord is too thin and/or if there's too much plugged into the cord (too much load), then your power conditioner isn't going to fix that. 

 

* This can be a nightmare if something like an AC motor, fridge or lighting rig is running on the same electrical circuit since it can not only potentially lead to an overloaded circuit, but devices like that can also cause noise. A power conditioner can often be helpful here since they can reduce AC line noise, RFI and EMI, etc. The sound tech at the venue SHOULD know if the circuit is free and not being used by other electrical devices in the building, but unfortunately, oftentimes they don't have a clue. 

 

 

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Posted (edited)
1 hour ago, Phil O'Keefe said:

 Not necessarily - you can use an extension cord as long as it is beefy enough. Again, just make sure that there isn't a bunch of other stuff plugged into the same electrical circuit - which isn't always obvious since multiple AC outlets in a building can share the same circuit.* 

 

No. If the extension cord is too thin and/or if there's too much plugged into the cord (too much load), then your power conditioner isn't going to fix that. 

 

* This can be a nightmare if something like an AC motor, fridge or lighting rig is running on the same electrical circuit since it can not only potentially lead to an overloaded circuit, but devices like that can also cause noise. A power conditioner can often be helpful here since they can reduce AC line noise, RFI and EMI, etc. The sound tech at the venue SHOULD know if the circuit is free and not being used by other electrical devices in the building, but unfortunately, oftentimes they don't have a clue. 

 

 

To the * :  ugh. I’m afraid this is an old building. It is quite shocking (not literally) that there aren’t outlets right where musicians would sit. But I saw sets of four empty outlets over on the walls (to left and to the right) behind the curtains, as well as a set through a door on the stairwell that’s literally closer to us. (We’re behind curtains toward center stage.)

So I will at least be able to avoid crappy extension cords. There are rows of professional overhead stage lights. They must have those on an isolated circuit. Must!

I did NOT hear unwanted humming last night, so that’s a good sign. Will plug in amp at home tonight to see if I get that distortion at low volume. Perhaps the amp tech didn’t properly rebias the amp for new tubes.

Edited by arcadesonfire
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Posted (edited)
3 hours ago, Phil O'Keefe said:

Also, make sure any power conditioner you're considering has good surge protection too - power surges can destroy gear. 

On that note:

I've been in the electrical equipment industry since 1990, and hold a patent for a high-end surge protective device design. Pardon the long post, but there's a lot of pure garbage that gets stated about "power conditioners" and surge suppressors, and I think it's helpful to get down to the core facts of what they can and cannot do.

A "power conditioner" doesn't really protect your equipment in any way.  The majority of them are no more than a 60 Hz filter, with perhaps a bit of surge protection.  Unless you are dealing with a noise issue from another ill-behaving load on the same circuit (like a neon sign or failing refrigerator/fluorescent light ballast) , they really are just electronic jewelry.  Surge protectors, however, can provide real value in preventing transient over-Voltage events from damaging your gear or shortening its life.

There are two key performance factors that tell you how a SPD (Surge Protective Device) will operate in the real world, and a third that will give you a sense of how long it will live. The first two are the clamping Voltage, i.e., what is the highest Voltage that the SPD will let through to your equipment when it attempts to clamp a surge event. The second is the Peak kA rating, which determines how much transient energy the SPD can absorb without failing to clamp. These are required test values for any SPD that meets the UL SPD standard (1449, 4th edition). Peak current is sometimes called Nominal Discharge Current, and clamping Voltage is sometimes referred to as VPR (Voltage Performance Rating).

The third value is the total amount of energy that the device can absorb before its useful life is over. Most SPD are based on MOVs, which are sacrificial devices that lose some capacity every time they absorb a transient. A higher "Joule rating" indicates the total amount of energy that the device can take, which gives an indication of how long it will last in normal use. Be careful, though, as a high Joule rating means nothing if the device doesn't have a high enough Peak kA or low enough clamping Voltage rating to protect your equipment.

I like the fact that both Furman and TrippLite give clear, honest ratings information for their devices. It allows you to really compare what they do. The trouble is that many other manufacturers do not, so it can be difficult to get a really solid, fair comparison.

So, have a look at this product:
https://www.furmanpower.com/product/15a-merit-series-power-conditioner-wlights-M-8LX

Look at the spec page, and go down to the bottom, where it shows the peak impulse current, rated at 12,000 Amps. This is actually a pretty reasonable rating compared to most inexpensive "surge strips", as it is double the 6kA that is required for the VPR testing under UL1449. It's limited to 150 Joules so it's not a long-life device, but it will take a reasonable hit before it lets anything through to your gear. The real problem, though, is that the only protection modes are line-to-neutral. A transient that is line-to-ground would not be clamped inside the device, and would force surge current to travel through the neutral-to-ground bonding link either in your equipment or in the service panel. Not a common occurrence, but not a good outcome.

Now, compare to this product:
https://www.furmanpower.com/product/20a-advanced-power-conditioner-wsmp-no-lights-9-outlets-1ru-10ft-cord-P-8 PRO C

Note that it doesn't use MOVs, so there is no Joule rating - it should absorb surges throughout its useful life. Trouble is, its initial clamping value is only 3,000 A, and it's max is 6.5 kA - roughly half of the other device. It's about tradeoffs, and the trade-off here is that a relatively moderate transient event would pass through this device and get to your gear.

Now, what would I recommend? Something more like this:
https://www.tripplite.com/isobar-12-outlet-rack-mount-surge-protector-15-ft-cord-3840-joules-locking-switch-cover~ISOBAR12ULTRA

Have a look at the spec sheet. Clamping Voltage of 140VRMS. Peak current of 96 kA, which is more than a standard 120/240 VAC panelboard can handle. Joule capacity of 3840. UL1449 approved. Note that it also include Line-to-Ground and Neutral-to-Ground protection modes, as well. This is a serious SPD that actually does the job, and will keep doing it for a long time.

There's a lot of snake oil in this part of the electrical industry, along with some reasonably good products that are just over-priced for what they deliver. The key to not getting ripped off is to understand the specs and use them to understand what the various products will really do.

Full disclosure - I used to run the engineering team for a company that made SPDs (not one of the ones I have mentioned here). I've moved on to another part of the industry, so there's no conflict of interest with this post.

Finally, as Phil noted above, your power cables should be as short and as thick as you can get them.  I won't let anything smaller than 14 gauge anywhere in my gear, and I prefer 12 gauge.  As a comparison, the NEC (electrical code) won't let you wire any 120VAC service in any house or commercial building with anything less than 14 gauge wire, and higher gauges are required for long runs (to meet Voltage drop requirements).  12 gauge is required for 20 Amp circuits.

 

Hope this helps....

Edited by SteinbergerHack
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Posted (edited)

First, 12ga extension cords with quality plugs and connectors. I use 12ga SO or SOOW cord with Leviton industrial hardware, you make them up yourself. Second, take a VOM with you and check the actual voltage when everyone else is plugged in, if it's an older venue it could be everything is running off of one circuit or the circuits have other devices pulling from them that are not on the bandstand. JMO

Here is one of mine.

20200310_095250[1].jpg

Edited by Telecruiser
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5 hours ago, AJ6stringsting said:

12 ga. , an ETA power conditioner and the it feeds into my Monster 2500 power conditioner ....never failed to give me surge protection and kills any RFI interference.

ETA makes some decent stuff - the EPD8LR would be a really good choice for just about any rack application.

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I been dealing with surge protectors for at least 40 years now.  I work in the business equipment industry and we include one with every piece of equipment we sell.

ESP, The manufacturer guarantees repairs on any piece of gear damaged by a voltage surge.  So far we've only been able to collect on a couple of them and even there we couldn't be sure if the damage was caused by an actual surge or defective surge protector which simply failed. 

What you don't know is how many times that unit actually did its job and protected the gear.  Most do not have any kind of logic to tell you how many times its protected, but we do have new style units that actually have that and are sold with units costing over 100K now.  Given the fact most business equipment is networked these days its important their power source isn't loaded with voltage spikes which can cause data and reboot problems when there is voltage problems, especially in a city like Houston which is noted as being the most air conditioned city in the US. 

Between all those AC units and violent tropical storm systems we see here, it put allot of stress on the AC grid and the surge protectors seem to arrest the spikes that can do the most damage. 

To the OP.  What power conditioners cannot do is prevent the loss of power.  They can prevent large spikes in voltage but only a UPS/battery backup or a backup generator can prevent low voltage/brownout conditions.  If the voltage sags, it sags.  nothing you can do about it.  If the conditioner is any good it only protects against voltage spikes and noise as SteinbergerHack mentioned.  For most tube amps they don't do jack squat for you, in fact they might introduce more noise then they remove if its a conditioner designed for  computers. 

Your power transformer in a tube amp does far more to separate your gear from the AC supply. Its primary coil is separate from the secondary coils and only mirrors what the primary coil sees using inductive transference.  The secondary is then converted to DC where there is plenty of capacitance to smooth any spikes that may make it past the transformer.   AC voltage would need to be a good 20V lower before much of a difference in tone might be heard with most tube amps. The exception might be when the amp is a hybrid and has SS components that have narrow voltage parameters. 

Having played enough clubs to know what you're dealing with your issues may be related to beat up outlets with damaged grounds. Last club I played that had stage outlets, most of those outlets were so beat up you could barely get a connection and if you did they were so loose the music could vibrate the plug right out of the wall. 

The bass player in my band is a licensed  electrician with full certifications.  When we play a club that has bad/questionable outlets he brings an electrical snake that connects directly to the breaker box.  We also use 20 amp isolation transformers which takes us off line and prevents ground loop issues too. 

Given the OP's description I think the cause of his issue probably doesn't have anything to do with the power. Its more likely a defective tubes.  If you didn't buy the tubes yourself you have no way of knowing whether they stuck used tubes in that amp either.  Its not like tubes have a meter on them to tell you how many hours they've burned. 

Even buying them from reputable dealers is no guarantee you couldn't have gotten some defective tubes.  Last time I bought tubes for my Blackface I had to send the first 2 sets back  for being defective.  I bought Ruby tubes first which means they were shipped from china to Ruby half way around the world, where they unboxed and powered each one for matching them.  Matching doesn't test the audio quality, it simply measures current rating for biasing.  After that they reship them to customers so the elements have seen allot of vibration and banging around being shipped. 

The first set started arching out with large popping within 30 seconds of power up.  They went back immediately.

Second set were JJ's and had the same kinds of issues.  Noise in the background when simply idling.   I learned a long time ago tubes don't get better as the burn in. They only get worse. The third set were Electro Harmonix and were as good as another set I bought for another amp.  The JJ preamp tubes were awful too. Low output,  Midrange tones and distorted easily.  I switched to JJ's and it was like day and night.  Bright, clean, low noise and low distortion.  Makes a Fender amp sound Like I was using RCA tubes in it again. 

I had good luck with Groove tubes too.  Got nearly 20 years out of that set.  Fender owns them now which is a good move for them.  The tubes are sold with three different power levels so you can choose clean, driven of in between depending on the amp you have. 

My advice.  if the amp sounds bad at home, I doubt the power at that gig had anything to do with it.  You may have moved the amp before the tubes had time to cool off and damaged its filaments when knocking the amp around.  The other possibility is the load was incorrect for the head.  An impedance too high will burn your power tubes up very quickly and the fidelity can go right down the tubes.  (Pun Intended)  In other cases you can even damage or blow the screen resistors.  Check and make sure make sure the power tubes don't glow cherry red. If they have a blue tint you're probably OK.  If you have an extra preamp tube try swapping them one at a time and see if you can isolate the bad one. 

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assuming you are not using a rack, Furman does make a power conditioner/surge suppressor in a power strip configuration; I have used one for almost a decade. I like this one because it has spaced outlets to accommodate wall warts and large industrial plugs; there are other models like the SS6B which are straight in-line. We've used a Furman w/lights like SBH linked to in our band PA rack for about twenty years.

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15 hours ago, SteinbergerHack said:

ETA makes some decent stuff - the EPD8LR would be a really good choice for just about any rack application.

I bought my ETA power conditioner in 1997, it's still works great. A nasty power surge hit, all I had to do was put in a new fuse and it was still good as new.

Is ETA still in business ?

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Posted (edited)
On 3/10/2020 at 6:08 AM, thankyou said:

Not intending to hijack the thread, but there's an amusing story from the documentary, "Miracles out of Nowhere", the story of the band, Kansas.  They had a gig where they opened for Aerosmith.  Somebody, knowing that Kansas had been quite successful, warned Kansas about Steven Tyler's practice of unplugging an opening act if he thought they were getting too much positive attention.  Kansas came up with an alternative plan.  They plugged a bunch of cords into some outlets near the stage, but the cords just went towards the equipment and didn't serve any of the amps.  They found other outlets and as secretly as they could, ran the cords to their amps.  When Tyler started his little venture, nothing happened and Kansas continued playing to huge crowd reaction.  Tyler went into meltdown about it.  

I heard Mr. Tyler tried that with Pat Travers and Van Halen too.

Quiet Riots road manager did the same stunt on White Snake , when John Sykes was playing for David Coverdale.

Edited by AJ6stringsting
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4 hours ago, AJ6stringsting said:

I bought my ETA power conditioner in 1997, it's still works great. A nasty power surge hit, all I had to do was put in a new fuse and it was still good as new.

Is ETA still in business ?

Yes.  Monster is not, however.

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