"Mr.T" MrT@home wrote in message
u...
"Alan Rutlidge" wrote in message
...
Yes, I'm sure they do. With a SS BTL bridged power amplifier, reading
the
output might be problematical with a nice solid earth on one leg.
You have already heard of transformer coupling I assume, if you are using
bottles.
Actually if you read back a few lines I was actually referring to bridged
solid state (SS) amplifiers.
Obviously valve amps with transformer coupled outputs present no problem in
this case, nor would a normal single ended (non-bridged) output SS
amplifier.
How do you go about determining the maximum output at the onset of clipping
with a soundcard? Surely most soundcards alone would not be able to accepts
input voltages of more than a few volts without some form of attenuator at
the front end to prevent overloading? Would this not involve additional
components?
I notice that the Audiophile 192 soundcard you provided the link to (thanks)
does have a maximum input voltage limitation of 4 volts RMS, which across an
8 ohm load only amounts to 2 watts RMS - not a particularly powerful
amplifier. Whereas my AWA F242A N&D set will accept up to 30 volts RMS
without the need for external attenuators allowing amplifiers of just over
100 watts RMS (assuming an 8 ohm load) to be evaluated for power output,
distortion and noise performance. Still need a suitable dummy load though.
Jug elements - hmmmmm... nice constant resistance when they warm up?
Just like wire wound speakers.
I'm curious about this. Just based on reading a conventional kettle
element, the hot and cold resistances aren't the same. Typical readings are
58.2 ohms cold resistance; 24.2 ohms hot resistance (water boiled). Would
this temperature co-efficient characteristic not be similar in a jug element
and would it need to be immersed in water for cooling if measuring the
output an amplifier with several hundred watts output at or close to full
power?
As a matter of interest what is the typical resistance of a jug element?
Cold =,? hot = ?. Could be a lot cheaper alternative to a 300W wirewound
resistor mounted o a ruddy great heatsink.
Does it work just as effectively with toasters?
Quite possibly, but I've never tried.
Actually I thought Phil might be able answer that one. :P
Cheers,
Alan
Never really thought of them but
I assume you've tested them (jug elements that is) for suitability and
stability. Personally I find the average PC soundcard has a bit too much
residual background noise of meaningful noise measurements in high
performance gear, but once again these may only be the limitations of my
PC
and not necessarily yours.
Exactly!!
(I did say *decent* sound card. Try
http://www.m-audio.com/products/en_u...e192-main.html for a
relatively inexpensive example)
MrT.