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Old 27th February 2013, 12:42 AM   #41
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Quote:
Originally Posted by dadod View Post
Antonio simulation shows output voltage before an inductor(.ac sim) only. Certainly it shows an influence of the cap connected after an inductor influence, but the same influence shows on the voltage after an inductor. I was trying to show the difference between output voltage(or in my case, impedance) after and before a inductor, actually a speaker line garbage suppression by showing V(out)/I(I1)/V(vout)/I(I1) in dB. Could be that my result are not good enough, I did not include any cabel resistance/capacitance, but I think it was not importand.
Sorry but it not easy for me to express my self in English technically correct.
BR Damir
I think your simulation is not a reliable indicator of RFI behaviour.
A constant current source in series with the output inductor can provide essentially unlimited volts to maintain the current as the impedance increases.
Surely this can not be realistic?

Do not worry about the difficulty to express yourself. You ideas make sense whereas many native speakers write fluent nonsense.

Best wishes
David
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Old 27th February 2013, 04:13 AM   #42
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Quote:
Originally Posted by dadod View Post
JLH used 0.22R only and I like the sound of that amp.
I suspect he may also have done it 'soften' the sound by reducing the damping factor but of course I cannot be sure. But, this is still not the best way to couple an amp to a speaker. And, if the amp is not stable without the resistor, or with an inductor, then those are separate, fundamental issues that should be resolved first before inserting the resistor.
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Old 27th February 2013, 06:03 AM   #43
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Quote:
Originally Posted by Dave Zan View Post
I think your simulation is not a reliable indicator of RFI behaviour.
A constant current source in series with the output inductor can provide essentially unlimited volts to maintain the current as the impedance increases.
Surely this can not be realistic?

Best wishes
David
Hi David,
I am not telling that I do all correctly, I am not a spice specialist, still learning to use it.
Please look again this link, it explains how to simulate an output impedance in LTspice. This is a small signal analysis and the current source is used as a load here.
http://www.cs.toronto.edu/~relu/audi...pice-zout.html
BR Damir
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Old 27th February 2013, 06:06 AM   #44
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Quote:
Originally Posted by Bonsai View Post
I suspect he may also have done it 'soften' the sound by reducing the damping factor but of course I cannot be sure. But, this is still not the best way to couple an amp to a speaker. And, if the amp is not stable without the resistor, or with an inductor, then those are separate, fundamental issues that should be resolved first before inserting the resistor.
Yes I think the bass is a bit softer and not so punchy as with my TT amp with high dumping factor.
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Old 27th February 2013, 09:20 AM   #45
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How do you find it images left to right and front to back compared to your TT amp?
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Old 27th February 2013, 09:38 AM   #46
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Originally Posted by dadod View Post
Hi David,
...I am not a spice specialist...
Please look again this link, it explains how to simulate an output impedance in LTspice.
I also am not a Spice specialist, that's why I wrote with a question mark
My hope is to learn as we work this out.
I read the article earlier and understand it calculates output impedance but I am not convinced this is a useful way to simulate RFI tolerance.
Edmond Stuart did some RFI simulation of his new front-end and I will check there to see how he did it.

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David
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Old 27th February 2013, 10:18 AM   #47
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Originally Posted by Bonsai View Post
How do you find it images left to right and front to back compared to your TT amp?
Tough question, I am not good at this. First of all TT is my design, and JLH was modified by me. I like both, JLH with laterals is softer and less powerful, imaging is good for both. I never have a chance to have someone with "golden" ears to listen at my house and to give some opinions.
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Old 27th February 2013, 10:24 AM   #48
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Quote:
Originally Posted by Dave Zan View Post
I also am not a Spice specialist, that's why I wrote with a question mark
My hope is to learn as we work this out.
I read the article earlier and understand it calculates output impedance but I am not convinced this is a useful way to simulate RFI tolerance.
Edmond Stuart did some RFI simulation of his new front-end and I will check there to see how he did it.

Best wishes
David
I just simulated output impedance before and after the inductor and devided after impedance with the one before and got ratio in dB. How good this could be interpreted in RF suppression I am not sure.
BR Damir
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Old 27th February 2013, 11:28 AM   #49
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RF suppression and stability have a lot to do with the layout and track lengths. Spice will be inaccurate in the VHF if you do not include these strays.
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Old 27th February 2013, 12:13 PM   #50
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Originally Posted by davidsrsb View Post
RF suppression and stability have a lot to do with the layout and track lengths. Spice will be inaccurate in the VHF if you do not include these strays.
The question asked here was how much output inductor and associated Zobels helps to suppress a disturbances coming from the loudspeaker side, not RF in general. The layout was dicussed in length in an other thread.
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