Phil Allison wrote:

"John Stewart"


About a year & half ago I built a Loud Speaker Simulator very much like
that
shown in Phil's article. For the input L I have a 90 microhenry aircore
choke
followed by a 7.5R, 10 watt resistor. The low freqency resonance is formed
by a
Mallory 220 microfarad NP motor starting cap in parallel with a Hammond
159ZC
choke ( 60 mh, 0.7R).


** Such a low value for the input L means you are effectively simulating a
speaker that has a copper cap ( inductance damper) on the pole piece - ie
as is commonly used for wide range or twin cone speakers.

The bass resonance is at 44 Hz but the peak current before saturation is
only 2 amps for the 159ZC, so power input is a bit limited.

.......... Phil

The loudspeaker simulator has a nice measured peak at about 45 Hz.

The rise of impedance caused by the 90 microhenry choke starts at about 4KHz &
is well up at 10 KHz, similar to a real speaker. All of the parts were in my
pile, so easy to put together.

I've also got one each of the Hammond 159ZE & 159ZJ chokes, so other conditions
are possible. In all, very useful.

Cheers, John Stewart