Date: Fri, 31 Aug 2007 19:39:38 -0700
Reply-To: Michael Elliott <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Michael Elliott <camping.elliott@GMAIL.COM>
Subject: Re: Was: Mp3/FM + mono....reccomends? NOW: how much does your CD
unit draw??
In-Reply-To: <c4e7c5f90708311921y3d094db4yd6f13c1c87c5df0f@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I wouldn't worry about it too much. Amplifier A will need pretty much the same current
from the battery as Amplifier B when delivering the same power into Speaker C.
Manufacturers don't like to see their equipment get any hotter than needed else they need
to add heat$inking or suffer premature component failures due to overheating so there
won't be a lot of difference under no-signal conditions, either.
On the other hand, a 1000 watt amplifier is guaranteed to draw more current from the
battery than a 10 watt amplifier ... unless you play them at the same volume into the same
speakers.
--
Mike "Rocket J Squirrel" Elliott
71 Type 2: the Wonderbus
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
KG6RCR
neil N typed:
> cool. I found an ohms law calculator (yes I'm that lazy) online.
>
> I started to get to know that stuff when younger, but I understand
> what you're saying.
>
> It may be that my Kenwood isn't that much less efficient than the Sony
> though the only way to truly know, is to measure how much they each
> draw when set to the same volume output...... I think.
>
> Neil.
>
> On 8/31/07, Michael Elliott <camping.elliott@gmail.com> wrote:
>> Power and volts are related to each other that easily. The rated voltage is how many volts
>> the amplifier needs to operate, and let's just say it's 12 volts -- battery volts.
>>
>> Power is volts x amps. If the amplifier is sending (say) 20 watts into the speaker it
>> needs to get the power from someplace. Stick to watts. If your amplifier is receiving 12
>> volts from the battery, then in order to deliver 20 watts into the speaker it needs to get
>> at least 20 watts from the battery. With a 12 volt battery, the current needed is 20/12 =
>> 1.7 amps.* Actually more because the amplifier is not 100% efficient.
>> "Rated Power" refers to how many watts the amplifier can put into standard speaker loads
>> without exceeding a standard amount of distortion. Believe me, you don't want to get into
>> all this unless you really want to study audio electronics.
>>
>> * See Ohm's Law.
>>
>> --
>> Mike "Rocket J Squirrel" Elliott
>> 71 Type 2: the Wonderbus
>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>> KG6RCR
>>
>>
>>
>> neil N typed:
>>> I think I understand. But....
>>>
>>> Even though they use the term "rated power" in the same category as
>>> Amps/operating voltage used by unit, "rated power" refers to the
>>> actual audio output in watts and how it impacts how many amps drawn?
>>>
>>> "Rated power" does NOT mean "operating voltage" ?
>>>
>>> :^)
>>>
>>> Sorry for such elementary questions. I just found it hard to beleive
>>> that a newer unit would be that much more energy efficient only
>>> drawing 45 Watts.
>>>
>>> (though exactly how Sony got that figure. i.e. how loud stereo
>>> playing, is CD motor spinning, I don't know. Kinda like fuel mileage
>>> figures.... YaBaDaYabba.....)
>>>
>>> Neil.
>>>
>>>
>>> On 8/31/07, Michael Elliott <camping.elliott@gmail.com> wrote:
>>>> The phrase "rated power" refers to however watts the manufacturer claims the unit can
>>>> deliver into some speaker load. I think the KDC-S3007 is rated at 4 x 30 watts, which is
>>>> 120 watts into all four speakers combined. During that 120 watt exercise the power has to
>>>> come from someplace. Like your battery. That's where the 10 amp current draw comes in.
>>>>
>>>> If you're not playing any music, then the current draw will be quite a bit less. How much?
>>>> Depends on the design of the product.
>>>>
>>>> How much current does your Kenwood draw when you're playing the music you like at the
>>>> volume levels you like? Somewhere between 10 amps and the no-signal condition. It might
>>>> not be much more than the no-signal current draw, depending on how loud your music is.
>>>> Mellow Yellow's stereo draws about 1.25 amps when it's playing no music or just soft
>>>> music. If you're a head-banger and are clipping the shit out of your amp then you could be
>>>> drawing 10 amps, sure, and you're asking to be evicted from any campground I camp at. But
>>>> if you, like me, listen to soft music -- maybe a little Coltrane or Baker, maybe a bit of
>>>> Vivaldi or Puccini, whatever -- then you only need to worry about the amp's no-signal
>>>> current draw.
>>>>
>>>> --
>>>> Mike "Rocket J Squirrel" Elliott
>>>> 71 Type 2: the Wonderbus
>>>> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
>>>> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
>>>> KG6RCR
>>>>
>>>>
>>>>
>>>> neil N typed:
>>>>> Ok. So it seems that my in dash CD/FM unit is a "Kenwood" not a Panasonic.
>>>>>
>>>>> A search on the net' tells me the KDC-S3007 is 1996 technology. Hmmmm.......
>>>>>
>>>>> Like, duh.
>>>>>
>>>>> So I RTFM, and it say's:
>>>>>
>>>>> Operating voltage ........... 14.4 V (11-16 V allowable)
>>>>>
>>>>> Current consumption ...... 10.0 A at Rated Power.
>>>>>
>>>>> Via this page:
>>>>>
>>>>> http://www.angelfire.com/pa/baconbacon/page2.html
>>>>>
>>>>> it seems my stereo draws a staggering 144 Watts. Can this be??
>>>>>
>>>>> Another, ahem, more modern stereo, the Sony CDX-GT310 (kindly
>>>>> reccomended to me via pmail), draws 45 Watts.
>>>>>
>>>>> This could explain, in part, the big drain on my house battery.
>>>>>
>>>>> Like duh...... --- ;^)
>>>>>
>>>>> Just in case anyone else was having this problem!
>>>>>
>>>>> Neil.
>>>>>
>>>>>
>>>>> --
>>>>> Neil Nicholson. 1981 Air Cooled Westfalia -
>>>>> "Jaco" (Bustorius)
>>>>>
>>>>> http://web.mac.com/tubaneil
>>>>>
>>>>> Please send me your Vanagon/Westfalia links!
>>>>> http://vanagonlinks.googlepages.com/home
>>>>>
>>>
>
>
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