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Thoughts on the difference in sound between tubes and solid state

Started by Koreth, February 09, 2010, 04:16:59 AM

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flester

Surely the Tube Sound happened by accident. Tube amplifiers were used to make guitars louder and they did. Then SS amplifiers were used and they also made guitars louder using smaller components and less energy. But they sounded different. Why should we strive to make them sound tubey?

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jfetter

This is a harmonic profile pics of a triode single-ended.
I'm not aware of any solid state component that can do this across wide range of output levels.
The circuit is a 6sn7 / ne5532 hybrid.



teemuk

Any asymmetrically distorting circuit will produce similar profile. E.g. single-ended common emitter amp.

And no, triode (in a specific circuit) won't do it across a wide range of output levels either: With small signal input the magnitude of distortion is negligible, as usual. With modest overdrive the distortion profile is as depicted. And with harder overdrive the magnitude of distortion increases (this including higher order harmonics), second and third harmonics becoming less prominent overall.

With a push-pull circuit the same triode produces almost no even order harmonic distortion at all, as usual.

Loudthud

Quote from: teemuk on October 15, 2019, 03:43:04 AMWith a push-pull circuit the same triode produces almost no even order harmonic distortion at all, as usual.
That is true, until you start drawing grid current on the input side like when you overdrive a power amp. Depending on the source impedance, odd harmonics will drop out.

See experiment with TDA2040 here:
https://music-electronics-forum.com/showthread.php?t=48223


solidstate2199

To me the most obvious difference in the preamps ss vs tube
Is the onset "fizz" of the opamp or generally transistor when it
Starts to clip. At least i figure this is from transistors because all ss
Amps that i have do it.  I have a marshall 3203 which, if it wasnt for
That fizziness would sound rather close to a marshall 2204 or similar.
Maybe its just bad design from the old marshall ss amps.
Maybe jfet dont fizz.

edvard

Quote from: solidstate2199 on March 09, 2020, 02:54:37 PM
To me the most obvious difference in the preamps ss vs tube
Is the onset "fizz" of the opamp or generally transistor when it
Starts to clip. At least i figure this is from transistors because all ss
Amps that i have do it.  I have a marshall 3203 which, if it wasnt for
That fizziness would sound rather close to a marshall 2204 or similar.
Maybe its just bad design from the old marshall ss amps.
Maybe jfet dont fizz.

I'm inclined to believe the "fizz" is from "ringing" when the signal gets clipped.  Tubes naturally go from clean signal to squared-off clipping in a very gradual manner that doesn't "ring" like squared-off waves do.  Transistors are clean until they hit the limits, then *BAM*... Gibbs Phenomenon.  This is why people like (ab)using CMOS chips (and JFETs, to a lesser extent) for "tube-like" distortion; they exhibit a gradual onset of clipping as the signal approaches the limits, though not completely analogous.

Loudthud

CMOS circuits can fizz, especially when you lower the Voltage (this increases the gain) and you won't see any ringing on the waveform. Increase the Voltage and the gain goes down and they start clipping softer. Fizz is mostly from too much feedback. Solid state circuits have hundreds of times more feedback of tube circuits. A tube power amp may have 20dB of feedback. A typical opamp has 40 to 60dB or more feedback. Same goes for chip power amps.