[Boatanchors] Speech Amp

[rbethman]

V represents Voltage in terms of DC.  Even as far back in engineering 
tomes dated 1962.

AC voltages, even audio, has been represented as E.

Impedance also requires FREQUENCY.

The BC-610 input is actually 500 ohm, and is given with the frequency of 
400 - 3500 cycles.

70 VAC audio normally is 500 ohm.  Which the BC-610 takes quite nicely.

The 9.+ watts is MORE than the BC-610 needs.

Bob - N0DGN

J Forster wrote:
> Power = Voltage x Current:  P = V x I
>
> Ohm's Law:  Voltage = Current x Resistance      V = I x R, so  I = V / R
>
> Substituting:
>
> P = V x I  = V x ( V / R  ) or in computer V*V/R
>
> QED.
>
> -Jo9hn
>
> ===============
>
> rbethman wrote:
>
>   
>> AFAIK,
>>
>> This formula won't hunt!  Please provide reference for P = V*V/R.
>>
>> P = E*I,   E=I*R and etc
>>
>> Three phase power - P =   3*(1/2)  E line * I Line * cos Theta.  [That's
>> the square root of three BTW.]
>>     
>>> Since Power = V * V /R, if R=600 ohms and V=70 volts, there is only
>>> one possible power output from the amp. (4900/600 = 8.1 W)
>>>
>>>       
>> Bob - N0DGN
>>
>> J Forster wrote:
>>     
>>> Take a look here:
>>>
>>> http://www.dvq.com/hifi/images/260a.pdf
>>>
>>> AFAIK, 600 ohms is used for inputs, not outputs, and is typically
>>> balanced.
>>>
>>> A 70 V line means that the amp output is 70 V RMS at the amp's rated
>>> output. The 70 V is usually stepped down at each speaker to voice coil
>>> impedance. Typical transformers have taps for the desired wattage to
>>> the speaker, so you can hook up a number of transformer/speaker
>>> combos. So on a 10 W amp, you can hook up four 1 W and three 2 W
>>> speakers. The amp looks a lot like a voltage source.
>>>
>>> Since Power = V * V /R, if R=600 ohms and V=70 volts, there is only
>>> one possible power output from the amp. (4900/600 = 8.1 W)
>>>
>>> Nope, 600 ohm and 70 V are NOT the same.
>>>
>>> -John
>>>
>>> ==============
>>>
>>> Barrie Smith wrote:
>>>
>>>       
>>>>   It's my impression that the 70 volt output on a PA amp is 600 ohms.
>>>>         
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>>
>>>       
>> --
>> Bob - NØDGN
>>     
>
> _______________________________________________
>
>   

-- 
Bob - NØDGN