Members WynnD Posted May 21, 2014 Members Share Posted May 21, 2014 I'm trying to wrap my brain around an amp that claims to be 500 watts and the manual indicates 125 watt draw. Is this just taking 1/4 maximum output and not accounting for any power losses? Or are they lying through their teeth. (amp is an Ampeg PF-500) Ampeg used to be a respectable company. They changed? (My first bassist has an Ampeg tube amp of this style that was 40 watts. It was loud enough for our needs at the time.) Link to comment Share on other sites More sharing options...
Members dboomer Posted May 21, 2014 Members Share Posted May 21, 2014 The draw posted (125W) on the device is assuming 1/8th power so in this case at 62.5 watts output. This is the requirement of UL or ETL for listing the devices (uL65000) Link to comment Share on other sites More sharing options...
Members agedhorse Posted May 21, 2014 Members Share Posted May 21, 2014 Don is correct, the minimum acceptable agency labeling requirement is based on 1/8-power (long term average with 12dB peak to average ratio) but there is also the cavet that if the product is designed so that under normal operation it is intended to be operated above this level then the label number is allowed to be increased to reflect this. Link to comment Share on other sites More sharing options...
Members WynnD Posted May 22, 2014 Author Members Share Posted May 22, 2014 Thanks. I thought my brain was going to explode. I guess that I expected maximum draw levels. (Not that I live at those levels.) So as I understand you, they are listing the expected draw and not maximum draws. From a functional point, is this good enough to calculate maximum demands on a circuit? Link to comment Share on other sites More sharing options...
Members agedhorse Posted May 22, 2014 Members Share Posted May 22, 2014 Generally, yes. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted May 22, 2014 CMS Author Share Posted May 22, 2014 Let's put it this way...the QSC amp I'm presently evaluating has 4 ~1200w amps. Its display shows input voltage, and current draw. Running it (2 channels on subs and 2 on mid-highs) at levels you (Wynn) would consider quite reasonable performance levels, it draws 0.8a. Link to comment Share on other sites More sharing options...
Members dboomer Posted May 22, 2014 Members Share Posted May 22, 2014 From a functional point, is this good enough to calculate maximum demands on a circuit? Yes but remember it never hurts to have a healthy reserve as well. Music almost never pushes an amp to deliver it's rated continuous power. It does drive it to its peak output but when you subtract the dynamic range from the peak level you can see how much average power you are actually getting. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted May 22, 2014 CMS Author Share Posted May 22, 2014 I've also never tripped a breaker with amps. Ever. Some might say I'm just not trying hard enough... Link to comment Share on other sites More sharing options...
Members Axisplayer Posted May 22, 2014 Members Share Posted May 22, 2014 Craig, in the old days before LEDs, I reserved that right for lighting. Tripped lots of them then. Link to comment Share on other sites More sharing options...
Members dboomer Posted May 22, 2014 Members Share Posted May 22, 2014 Hey ... a few CS-800s on an extension cord and it was lights out Link to comment Share on other sites More sharing options...
Members RoadRanger Posted May 23, 2014 Members Share Posted May 23, 2014 Hey ... a few CS-800s on an extension cord and it was lights out Especially if you were runnin' the sub amps solidly in the red with the DDT switched off - Woo! Link to comment Share on other sites More sharing options...
Members musicnmotionz Posted June 14, 2014 Members Share Posted June 14, 2014 Craig, Which QSC amp are you speaking of? Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 16, 2014 Members Share Posted June 16, 2014 Don't get all crazy with "the Amps" like you sometimes do with "the db's" Link to comment Share on other sites More sharing options...
Members WynnD Posted June 17, 2014 Author Members Share Posted June 17, 2014 When you only have 2 - 20 amp circuits for an outdoor gig, you have to consider power usage. (I'm pretty sure that a single 20 amp circuit would trip between the PA, Bass and monitor amps.) At least it's early enough to not need any lights there. Our gig on the 4th of July will require lights too. (Don't know the power availability there yet.) I do have a tendency to overthink things, but I'd rather make sure things work out on paper before loading up. Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted June 18, 2014 Members Share Posted June 18, 2014 When you only have 2 - 20 amp circuits for an outdoor gig, you have to consider power usage. (I'm pretty sure that a single 20 amp circuit would trip between the PA, Bass and monitor amps.) Probably wouldn't. Never have a problem running my entire band on 2-20 amp circuits which presently consists of 2 powered subs, 2 powered tops, a powered monitor, FOH mixer, monitor mixer, a small guitar amp, 3 keyboards, 20 LED lighting fixtures, and a couple dozen or so various processors, effects devices, laptop computers, controllers, wireless receivers/transmitters, etc. And I'm pretty sure we push the mains and subs much louder than you prefer to play most of the time. The only time we've insisted on needing 3 circuits is when we were running some older traditional Par 56 cans. And even then we usually had no problem putting everything on two circuits if that was all that was available to us. (Just not running all the lights full-out all the time was usually all it would take). But as it is now, two circuits is fine unless there's something amiss in the circuitry. Older buildings/wiring can often present some unwanted surprises. Link to comment Share on other sites More sharing options...
Members WynnD Posted June 19, 2014 Author Members Share Posted June 19, 2014 I'm sure that if we get everything well split between the two circuits, we should be OK. Link to comment Share on other sites More sharing options...
Members StratGuy22 Posted June 19, 2014 Members Share Posted June 19, 2014 I've ran my entire sound rig & back line off two 20A circuits as well. The generator didn't have the 30A twist lock I usually use, it had the spike style which wasn't going to work that day. Link to comment Share on other sites More sharing options...
Members agedhorse Posted June 19, 2014 Members Share Posted June 19, 2014 2x 20A ckts. are not going to be a problem. Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted June 19, 2014 Members Share Posted June 19, 2014 Dealing with power is very often a "make do with what you got" situation. Yes, we stipulate that we require 3-20A circuits in our contract, and are usually given verbal assurances ahead of time that everything will be as we request, but then we show up at some otherwise beautiful venue out in Wine Country or someplace similar only to be handed a single extension cord sticking out of an outlet that appears to have been wired up sometime during the Coolidge Administration. And, of course, it's Saturday and whoever passes for "electrical engineer" at this venue is gone for the weekend. Sure, the signed contract would give us the legal right to walk out and not perform, but the real-world realities are that we are not going to do that. Instead we're going to huff and puff a bit, and then scramble around to find at least one more outlet that presumably belongs to some other circuit and gingerly wire up stuff, fire it up and hope for the best. In Wynn's case, I'd offer up the same advice he offers up for virtually every other situation on this forum: "turn down the volume!" Link to comment Share on other sites More sharing options...
Members WynnD Posted June 20, 2014 Author Members Share Posted June 20, 2014 This is our first public performance after joining up. I've had a ball at the 3 rehearsals in preparation for this two hour show. We have a 4 hour show coming up on the 4th of July. It will be interesting to see how much additional volume is reached for being the gig is outdoors. I'm bringing speakers for side fills, but not really expecting to need them. (Couple of SX100 EVs on tripods.) If there's a bit of restraint, things should go well. Link to comment Share on other sites More sharing options...
Members sibyrnes Posted June 20, 2014 Members Share Posted June 20, 2014 At a recent wedding I had to run a system for a rock/dance band consisting of two SRX 712's powered by a QSC 3602 over two PRX618S-XLF and two Alto Ts112A's as monitors. That and the band on one 20 amps circuit-no problems! Believe it or not! Beautiful facility, first class all the way and ONE circuit for the band:eek: Link to comment Share on other sites More sharing options...
Members Vito Corleone Posted June 20, 2014 Members Share Posted June 20, 2014 Beautiful facility, first class all the way and ONE circuit for the band:eek: So many times the people at these facilities don't even have a clue what a "circuit" even is. They think that if they give you 2 different outlets (or even two plugs on the same outlet) that they've provided you with 2 circuits. And, of course, sometimes they have. But good luck finding anyone at the place who knows which outlets go where.... Link to comment Share on other sites More sharing options...
Members Kalina2 Posted June 20, 2014 Members Share Posted June 20, 2014 Hi guys! I think that nothing bad will happen if we use just one power line ... Every Saturday, I use only one power line for "Martin black line," two heads "Martin" with gas discharge lamps - 250 watts, a couple of scanners "Martin" 250 W and a dozen different LED lights .... all my requests to spend more at least one power line, I hear only the fifth year promises Link to comment Share on other sites More sharing options...
Members wesg Posted June 22, 2014 Members Share Posted June 22, 2014 How are circuits fused in your country, Kalina2? In North America, the norm is a 15A circuit that is rated to run at 12A continuously. At 110VAC (the low end) that translates to 1320W assuming your equipment has a power factor of 1. If you are moving the same current in a 240VAC country, you only have half as much power available. Link to comment Share on other sites More sharing options...
Members WynnD Posted June 22, 2014 Author Members Share Posted June 22, 2014 Power wasn't a problem. I think my Airport Express expired. Fortunately, my DL1608 works fine with the ipad docked. Others aren't so lucky. This will be my first Apple product to fail under warranty. (Doesn't work lights flashing and won't reset.) Some have suggested that less use means longer life. This one only gets used for shows and rehearsals. It's never on when not needed. Will see what Apple says. Thanks for all the replies. Hated using all the extension cords. It was about 75' from the power to the staging area. Link to comment Share on other sites More sharing options...
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