Leach Superamp problems

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i am not spending my money on wheel caps !
Better on Chevys than on pills and thrills !

Here is an oldy that should be next to nothing on Ebay:
 

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Hi Guys,

Couple of questions.

The scope software that jacco linked says it is for Windows 95. Does anyone know if it will work on XP or 98?

Also, I have a couple of software tone generators. Any reason why those wouldn't work for this?

jacco,

When you say high value resistor, can you give me an ideal of what values to look for?

Thanks, Terry
 
still4given said:
Hi Guys,

Couple of questions.

The scope software that jacco linked says it is for Windows 95. Does anyone know if it will work on XP or 98?

Also, I have a couple of software tone generators. Any reason why those wouldn't work for this?

jacco,

When you say high value resistor, can you give me an ideal of what values to look for?

Thanks, Terry
It should work on 98. As for XP, as long as it does not use realmode DOS drivers you are fine.

:D
 
Terry,

sorry, i forgot to add the resistor part.
Regular soundcards have a line-in that can handle something in the order of 2 volts.
The mic-in you should not use, max voltage is only a few 100mV.

Means you risk blowing up your soundcard if input signal has a high voltage level.
You can add some protection by applying a voltage divider.
Suppose your Leach can have 75 volts max on the output.
If you take a 12 KOhm and a 200 Ohm resistor in series, the line-in of the soundcard connected to the middle of the two resistors, the end of the 200 Ohms connected to ground, max current would be 6 mA.
That way you can get away with a 0.5 watt resistor for the 12 KOhm, and max voltage on the soundcard entrance is a little over 1.2 Volts.

PC soundcards do 44.1 KHz or 48.
The scope program of the nice Russian gentleman goes up to 20 KHz.
if you like to take a closer look at your leach, get a scope for 50.
 
Some recent experiences tell me that some soundcards may not be able to drive a power amp. I became suspicious when an amp I was trying to insert in RightMark loop-back test showed unbelievably bad figures. (An aside: I already knew I needed a divider and isolation between the output and line-in.) While I don't have the most discerning ears I was pretty sure I would have noticed something amiss were the amp truly generating 20%THD!

Initially the added resistance from a 100k pot at the amp's input was sufficient to get believable numbers. Next step is a proper buffer.
 
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