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Old 9th January 2009, 10:03 PM   #1111
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I use the AP1 - the later products are too fancy for me, but we have an
AP2 on one of our benches here.

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Old 10th January 2009, 08:32 AM   #1112
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Hi Nelson
It would be nice if you could let us know if the B1 as per the the original design is predominantly 2nd or 3rd order harmonic distortion.
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Old 11th January 2009, 01:38 AM   #1113
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2nd.
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Old 11th January 2009, 08:40 PM   #1114
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Thanks Nelson
OK then hopefully I have made a mistake somewhere.
Can someone check the way I have drawn the circuit.
I am a little unsure about the signal ground/return and output ground/return, and the DC power ground/return.
Any help would be most appreciated.
Thanks
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File Type: jpg spice circuit.jpg (50.9 KB, 1343 views)
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Old 11th January 2009, 09:23 PM   #1115
JimT is online now JimT  Canada
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Quote:
Originally posted by thanh1973
Thanks Nelson
OK then hopefully I have made a mistake somewhere.
Can someone check the way I have drawn the circuit.
I am a little unsure about the signal ground/return and output ground/return, and the DC power ground/return.
Any help would be most appreciated.
Thanks
You do not have things setup completely for an FFT with LT Spice. Try adding the following directives.

.tran 0 30m 0.1u
.step param C list .100u .10100u
.option plotwinsize=0

Test at 1000Hz.

If you want to learn more about LT Spice. Try the forum for it on groups.yahoo.com. I am unable to help you further. I just copied the above from an example I found there. It works for me.

Jim
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Old 11th January 2009, 10:27 PM   #1116
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Just simmed tanh s circuit and indeed it shows that h3 dominates.

Tanh do the sim now at 20Khz and I think youll be even more puzzeled
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Old 12th January 2009, 12:16 AM   #1117
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Whenever spice doesn't match measurement, we look for flaws
in the models first. This would not be the first time that Spice JFET
models have come up a little short.

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Old 12th January 2009, 12:30 AM   #1118
udailey is offline udailey  United States
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Mr. Pass
I read a post by you that mentioned using the AP1 and some other attenuator after the source and before the amp with a buffer or pre inbetween. I cant for the life of me find it now. You talked about maybe having just a few different resistances to choose from before the buffer/pre and then after it to have, I think, the AP1.
Is this to help 'rectify' any source output/amp input impedance issues or what is the reason?
I think this was with a BOSOZ.
Thanks
Uriah
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Old 12th January 2009, 12:36 AM   #1119
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by udailey
Mr. Pass
I read a post by you that mentioned using the AP1 and some other attenuator after the source and before the amp with a buffer or pre inbetween. I cant for the life of me find it now. You talked about maybe having just a few different resistances to choose from before the buffer/pre and then after it to have, I think, the AP1.
Is this to help 'rectify' any source output/amp input impedance issues or what is the reason?
I think this was with a BOSOZ.
Thanks
Uriah

AP1 is measuring gadget , almost capable of computing 42 .

we don't ( we - spoiled kids ) even need to know exactly what's that beast ..........

anyway - I can just imagine using it as attenuator
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Old 12th January 2009, 12:38 AM   #1120
udailey is offline udailey  United States
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Ah, I thought it was the Apox-1
Uriah
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