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  Re: What to us for a PA dummy 300W load?         


Author: Michael Black
Date: Jul 21, 2008 11:28

On Sun, 20 Jul 2008, dave wrote:
> Looking for ideas here... I'd like test a PA amplifier rated at 300
> watts into 4 ohms.
> Any ideas as what I could use for an dummy load - apart from some
> actual speakers (drivers) that is! I'd also like the load to be as
> resistive as possible and not inductive as the drivers would be.
> As I don't have a 4 ohm 300 watt resistor in the spares box - any
> ideas what could be used as a "subsitute"?
>
I seem to recall reading about using a toaster, or at least the toaster's
heating element, as a load for an audio amplifier.

It likely helps to explain why you need the load. Once upon a time, every
amplifier needed a load, because the design required it. But most solid
state amplifiers can operate without a load, so the need for a load may
no longer be needed, depending on what you are doing.

Michael
no comments
  Re: What to us for a PA dummy 300W load?         


Author: Eeyore
Date: Jul 21, 2008 10:42

dave wrote:
> Looking for ideas here... I'd like test a PA amplifier rated at 300
> watts into 4 ohms.
> Any ideas as what I could use for an dummy load - apart from some
> actual speakers (drivers) that is! I'd also like the load to be as
> resistive as possible and not inductive as the drivers would be.
> As I don't have a 4 ohm 300 watt resistor in the spares box - any
> ideas what could be used as a "subsitute"?

There are loads of options. Farnell sell ultra-large wirewound resistors
for example.

Graham
no comments
  Source for new old stock or pulled LM741CN Op Amps         


Author:
Date: Jul 21, 2008 10:26

I am looking for a few LM741CN chips made in the 1970's. Does anyone know of
a source for new old stock or any old equipment that used them that can be
obtained cheap to remove them from?

Thanks!

10 Comments
  Re: What to us for a PA dummy 300W load?         


Author: Jean-Yves
Date: Jul 20, 2008 23:51

In article 4ax.com>,
dave 127.0.0.1> wrote:
> Looking for ideas here... I'd like test a PA amplifier rated at 300
> watts into 4 ohms.
> Any ideas as what I could use for an dummy load - apart from some
> actual speakers (drivers) that is! I'd also like the load to be as
> resistive as possible and not inductive as the drivers would be.
> As I don't have a 4 ohm 300 watt resistor in the spares box - any
> ideas what could be used as a "subsitute"?
--
Jean-Yves.
no comments
  Re: What to us for a PA dummy 300W load?         


Author: RST Engineering (jw)
Date: Jul 20, 2008 19:16

First you have to tell us what "rated" means. Is this 300 watts pure sine
wave power or the poorly defined "music power". I doubt that there are
speakers available that would take 300 watts CW.

Jim

--
"It is the mark of an educated mind to be able to entertain a thought
without accepting it."
--Aristotle

"dave" 127.0.0.1> wrote in message
news:rvb784hr7086opqfqf0d4qpth9mm38u4f5@4ax.com...
> Looking for ideas here... I'd like test a PA amplifier rated at 300
> watts into 4 ohms.
> Any ideas as what I could use for an dummy load - apart from some
> actual speakers (drivers) that is! I'd also like the load to be as
> resistive as possible and not inductive as the drivers would be.
> As I don't have a 4 ohm 300 watt resistor in the spares box - any
> ideas what could be used as a "subsitute"?
1 Comment
  Re: What to us for a PA dummy 300W load?         


Author: DaveM
Date: Jul 20, 2008 15:20

"dave" 127.0.0.1> wrote in message
news:rvb784hr7086opqfqf0d4qpth9mm38u4f5@4ax.com...
> Looking for ideas here... I'd like test a PA amplifier rated at 300
> watts into 4 ohms.
> Any ideas as what I could use for an dummy load - apart from some
> actual speakers (drivers) that is! I'd also like the load to be as
> resistive as possible and not inductive as the drivers would be.
> As I don't have a 4 ohm 300 watt resistor in the spares box - any
> ideas what could be used as a "subsitute"?

You will probably get advice to use a string of light bulbs for this purpose,
but I have to advise caution there. The resistance of an incandescent bulb is
very low when cold, and rises significantly when current is applied. It's not
easily predicted and can lead to blowing your amp. The bulbs can easily look
like a short to the amp when cold and kill it before you get started with a
test.
You should look for something that has less resistance change when heated.
Thinking of the heating element from a toaster, electric frying pan, electric
space heater or other household appliance. Of course, you'll have to measure
and combine appliances as appropriate to get the right value.
Show full article (1.46Kb)
1 Comment
  Data entry jobs         


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Date: Jul 20, 2008 05:00

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  Earn 30000 Internet Jobs         


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  Work at Home - $250+/Day         


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Date: Jul 20, 2008 04:51

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