It isn't as simple as adding higher tube distortion. The Carver concept of transfer function actually works though, to signmake a solid state amp sound like a matching tube amp, which is exactlly matching the electrical output of two amps. But I suspect the reverse won't work, matching a tube amp to a solid state one. Carver did the comparison matching one of his amps to I believe a Conrad Johnson. The listening panel agreed(after 2 tries I think). And I personally spoke to Gordon Holt and he confirmed that Carver suceeded.
A Black Box to Solve Everything
Tubes vs. solid state?? There's a thread out right now about this exact question (there always is), but I didn't want to take it off subject. So my question is; is there a device that could go between the preamp and amp that has variable harmonic distortion capabilities? I know there are tube buffers, but they are not really addressing the point because they use line level signals and don't have the distortion of a good 300B tube being pushed beyond its limits. My thinking is that of a black box with switches and knobs to adjust harmonic distortion to mimic different tube types. It would also have to have a bypass switch so we could readily and quickly A/B the thing. Any ideas?
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About a year ago I watched a video (on YouTube iirc) in which Nelson Pass spoke about an amp he was working on, one that was intentionally designed to add harmonic distortion to the input signal. He also explained the rationale for doing so. I could be mistaken, but I think it may have been in an interview with Steve Guttenberg, recorded in Nelson's listening room. |
Nelson Pass's DIY Nutube preamp kit allows for adjustment of distortion. Here is a description from the design document: "The attraction of the Nutube in an audio circuit is the Triode character, allowing adjustment of the distortion by operating the device in a specific voltage/current load line. For a given amount of current through the tube there is a point at which the square law effects of Cathode current and Plate voltage cancel, nulling out 2nd harmonic distortion and leaving 3rd harmonic. This is the lowest output distortion setting. If you increase the Plate voltage, the circuit takes on a positive phase 2nd harmonic distortion character, and if you lower the Plate voltage it has negative phase 2nd harmonic. These distortions increase as you adjust the Plate voltage farther from the null point" |
THAT'S the one @clio09! So it's a pre-amp, not an amp. I'd love to hear Nelson and Ralph Karsten discussing the related subject together. Roger Modjeski too, but that's not going to happen. |
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