On Thu, 28 Jul 2005 13:21:04 +1000, "Phil Allison"
wrote:


"Robbie"

I want to put a load on small tube amps that simulates the reactive load
of a
speaker, not just a resistor... I know that spk models are very complex,
but a
simple circuit should be possible. I'm thinking of a regular full range
spk like
a guitar amp speaker, shouldn't be too hard? I saw such a circuit before
but
can't locate it.



** Figure 2 in this article has what you are asking for:

http://sound.westhost.com/vi.htm


The resonant frequency of the parallel tuned circuit is 50 Hz .

You could alter the inductor to 10 mH and the 22 ohms to 33 ohms for
simulating a guitar speaker.


Hey thanks a lot!

I notice the 6r8 resistor and the coil - should I compensate these values, EG if
the coil was 6r8 then I wouldn't need the resistor? Just from experience I
expect a 1mh coil to be around 200 turns free air... maybe a few ohms depending
on the wire I can find.

Also, that cap is big, I guess a back-to-back electrolytic?

Thanks again!