Power requirements of sound system

Desert Rat
Desert Rat Solar Expert Posts: 147 ✭✭✭
in Off Grid Solar & Battery Systems #1
I'm installing a small solar electric system that will power a PA system. Another guy is supplying the sound equipment, and we are having a disagreement.
Here are the published specifications of a powered speaker that will be used in the system (there will be two of these speakers).

Amplifier
    Low frequency range  Max output power    700W
    High frequency range  Max output power   300W

Power supply
    Voltage (fuses)
          120V, 60Hz (T6.3A H 250V)
    Power consumption    Max 110W

What I'm concerned with is the electrical draw of the speakers. Looks straightforward to me:  Max 110W as stated in the specifications.
He says they can draw 12.6 amps @ 120 volts, but I think he's confusing the fuse size with actual power draw. He also says that "if the speakers can put out 700 watts, they can draw 700 watts". I think he's comparing apples and oranges. Comments?
· Share on Twitter

Comments

  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    #2
    Yes 700w is 700w, the thing is most sound systems are rated at a true peak, the most they could possibly output before blowing the speaker.  So imagine that loud screech of feedback, that might pull that much for that second or two.  Most likely you are running 1/10 that during a loud song and 1/100th of that for speaking again unless your running white noise flat out.  I would make sure you get a true sine wave inverter of a minimum of 1000w, but I would guess realistically your going to pull 100w average with a "loud" song.  If you get a mod sine wave you will get a lot of buzz and the amps will get a lot warmer and burn out.

    Honestly for a system like that you might look at 12v system from a good auto setup and avoid the inverter.  The other option would be a powered speaker with a battery / amp built in, far less picky about the power you feed it and the amp and the speakers are matched for each other.  But it all depends on what you intend to do with the system.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #3
    From what little I know--Audio power output ratings are basically "lies".

    Your best bet is to get a Kill-a-Watt type meter and measure the actual loads (rough peak wattage), and kWH per session/day/etc... Even if the audio system can output 110 Watts--It would be unusual for the system to output that power level continuously--Real audio is going to have high and low volume output running. You need the total power usage under field conditions.

    http://www.solar-electric.com/kiacpomome.html

    Note that audio systems can also be pretty efficient or very inefficient (i.e., AC power consumed may have little to do with the level of audio output). Again, the Kill-a-Watt meter will tell you a lot.

    -Bill

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
    · Share on Twitter
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    #4
    A sales brochure tells lies?  Bill, are your sure?  Hee hee.

    The other thing is that some of the new gear automatically goes to stand-by and draws very little power. The subs will shut down and the system can be very efficient. I know the nice Yamaha unit that Costco sells is so efficient that you see mostly audio power on the
     K-Watt.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

    · Share on Twitter
  • H2SO4_guy
    H2SO4_guy Solar Expert Posts: 213 ✭✭✭
    #5
    Depends on how it is played.  If the bass is pushed hard, the Kill-A-Watt meter will have trouble picking up the peaks and sharp fast peaks (Like thumping bass) can take a battery down quicker than the numbers would imply.  Also depends on the headroom of the inverter to handle the peaks too.  The Peukert effect is a factor on the large quick power draws to charge the transformers and caps on the amps. 

    Bottom line, if it is loud, it will last a lot less time than expected. 


    12K asst panels charging through Midnite Classic 150's, powering Exeltechs and Outback VFX-3648 inverter at 12 and 48 volts.  2080 AH @ 48 VDC of Panasonic Stationary batteries (2 strings of 1040 AH each) purchased for slightly over scrap, installed August 2013.  Outback PSX-240X for 220 volt duties.  No genny usage since 2014. 
    · Share on Twitter
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #6
    Dave, which Yamaha units are you referring to?  I looked and only see exterior speakers on the .Ca site. Are they only in the US?
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
    · Share on Twitter
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,891 ✭✭✭✭✭✭
    edited March 2016 #7
    Just saw it again yesterday on my monthly costco run out of the mountains. Gawd I hate the civilized world of city life.
    Some items are not on-line and they had a Sony unit also. I think the Yamaha had 2 billion watts in 7 speakers.

    I found this link but I do not know which model I saw.... sorry.

    http://www.avsforum.com/forum/90-receivers-amps-processors/2185057-costco-receivers-yamaha-rx-v775-vs-yamaha-tsr-5790-a.html

    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

    · Share on Twitter

Categories