Re: How can I make a spk simulator load
- From: "Phil Allison" <philallison@xxxxxxxxxx>
- Date: Sat, 30 Jul 2005 10:57:29 +1000
"John Stewart"
> Phil Allison wrote:
>
>> "John Stewart"
>> > Phil Allison wrote:
>> >
>> >> >
>> >> > 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.
>> >
>> >
>> >
>> > 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.
>>
>> ** As usual, you are totally wrong.
>>
>> Your circuit only rises to 9.4 ohms at 10 kHz while typical woofers have
>> inductance figures of 0.5 to 2.5 mH - depending on coil size. The
>> impedance
>> at 10 kHz is 20 to 30 ohms, unless a copper shorting ring or pole cap is
>> fitted.
>>
>> Then the figures are like your circuit.
>>
>> ........ Phil
>
> Thankyou for your indication of confidence in my work. I actually measured
> that
> thing & those are the results.
** What a liar - you posted no figures at all.
............ Phil
.
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