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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?

koestner
clio09
3,355 posts
 

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"

bdp24's avatar
bdp24
9,815 posts
 

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.

wolf_garcia
6,704 posts
 

Who wants their hifi rig to push a 300B to distortion? Hmmm...Pass is into "tube like" sound as illustrated by his XA-25. I have one and it sounds great but not particularly like tubes to my ears...I switch between that amp and a Dennis Had SEP.  SS guitar distortion pedals into a tube guitar amp can sound amazing. I have various ones including my old 1980 ProCo Rat that is my fave...a supposed magic Motorola LM308 transistor is the key to that tone.

greg_f
106 posts
 

I guess you could try a unity gain tube buffer which is normally used for impedance matching between components, I remember reading somewhere there was even a SS device which emulated the 2nd (and others?) harmonic of a tube and the distortion (magnitude of harmonic) was applied in variable steps. I can't recall where I have seen it, I will have a search.

tomrk
73 posts
 

Such digital signal processors already exist.   I've seen them and used them.   They can mimic tubes, all sorts of distortion, and create a unique sound in many ways:

The secret of the perfect sound

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