j-FET / Triode Phono front-end
- Cressy Snr
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#286 Re: j-FET / Triode Phono front-end
I don’t need to tune my OTL for 1% 2nd harmonic. It already produces that by the time it reaches 200mW
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- IslandPink
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#287 Re: j-FET / Triode Phono front-end
I don't think so, but then my system would already have some 2nd-harmonic.izzy wizzy wrote: ↑Sat May 04, 2019 1:53 pm
Do you think you were tuning for "1% negative phase 2nd harmonic"?
I remember that I had a first set-up and then a modified set-up that I preferred. Andrew set up a quick Spice model, the first set up on Spice showed essentially no distortion, the preferred set-up showed a 2nd-harmonic peak at 70dB down. The difference in perceived tonal quality was quite significant.
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- izzy wizzy
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#288 Re: j-FET / Triode Phono front-end
Nick mentioned something like that when tuning one of his amps.IslandPink wrote: ↑Sat May 04, 2019 2:10 pmI don't think so, but then my system would already have some 2nd-harmonic.izzy wizzy wrote: ↑Sat May 04, 2019 1:53 pm
Do you think you were tuning for "1% negative phase 2nd harmonic"?
I remember that I had a first set-up and then a modified set-up that I preferred. Andrew set up a quick Spice model, the first set up on Spice showed essentially no distortion, the preferred set-up showed a 2nd-harmonic peak at 70dB down. The difference in perceived tonal quality was quite significant.
I saw something similar in the sim for the output on my phono in that the imbalance of the diff stage with a small tail was a similar harmonic profile to a single ended stage where if the tail had a CCS to force better balance, the 2nd fell away.
It's amazing how so little can make a difference.