What exactly is "tube warmth"?

[Jay2U]

Tube warmth is the heat caused by the filament.

 

[ThisBass]

A Marshall guitar amp with a well designed bass enclosure is killer.

An SVT with a fridge is a killer, but that's only me.
An SVP pro with a Digam 5000 is a killer, but that's only me
Anything is a killer, but I ain't to be anything.

 

[MDBass]

Nope, there are even and odds added.
The 2nd may be strongest in context, that's all.

I’m well aware both are added.

The OP is specifically asking about the phrase “warmth”.

“Warmth” comes from the added even harmonics, which are also sometimes described via the other adjectives I mentioned.

Odd harmonics are never described as “warm”: they are made up of thirds and instead of 5ths and octaves, which makes them gritty and aggressive sounding.

Brian May’s tone is a classic example of even harmonic warmth: Dimebag Darryl’s tone is a classic example of odd harmonic grit and aggression.

 

[Koshchei]

Tube warmth is a Czech man using century-old equipment to hand-make electronic lightbulbs after several pints over lunch.

The other kind of "tube warmth" is the steaming-hot ******** that some people invent when they romanticize them.

@agedhorse's posts are the only ones you really need to read in this thread.

 

[ThisBass]

It’s the even harmonics being added to the signal from driving the tubes.

Generally described as “warm”, “thick”, or “round”.

Why don't you do mention the odd harmonics that are naturally involved as well?
Why don't you do mention the interaction/relationship of even vers odd harmonics that may provide a distinct/unique texture of sound?

 

[SoulReflection]

I love the warmth of my Ampeg 20T for my home studio but I have also owned two, modern, class D amps. I have an Ampeg 15 plugin for Reaper and it does emulate a tube amp extremely well.

I agree with @agedhorse and others that the current offerings of Class D's can come very close to the warmth of tubes.

If I was playing out, current Class D's would be my choice for price, power, weight and sound.

 

[dbsfgyd1]

And weight. Warmth must be very heavy.

Well, when you lug an 80lbs SVT up three flights of steps, Brother it’e warm! LOL!!!

 

[legalbass]

@agedhorse's posts are the only ones you really need to read in this thread.

That is typically the case.

 

[Paul New]

My first bass amplifier was an Ampeg B18X. Second was a Dual Showman. I loved the way they both sounded, but also love the way my modern and older GKs sound. They all are very different from each other. If someone figures out the toobyness please copy me when you send the memo.

 

[ThisBass]

Tube warmth is a Czech man using century-old equipment to hand-make electronic lightbulbs after several pints over lunch.

Might be a true story cause the first Pils was brewed in Pilsen (Czech) in the year of 1842

 

[MDBass]

Why don't you do mention the odd harmonics that are naturally involved as well?
Why don't you do mention the interaction/relationship of even vers odd harmonics that may provide a distinct/unique texture of sound?

The OP is asking where the “warmth” from tube amps come from.

It’s from the even harmonics: odd harmonics don’t sound “warm”.

I explained all of that, including both technical detail as to the “why” as well as real world examples of each, in the reply that you’re now totally ignoring in order to continue arguing.

 

[ThisBass]

The OP is asking where the “warmth” from tube amps come from.

It’s from the even harmonics: odd harmonics don’t sound “warm”.

I explained all of that, including both technical detail as to the “why” as well as real world examples of each, in the reply that you’re now totally ignoring in order to continue arguing.

At best you explained your persoanl imaginations, science wise you did explain nothing.
Again adressed to you, how do you explain to other folks the relationship/interaction of even and odd order harmonics in the total outcome of sound?
Thank you!

 

[Patrice B]

This one is pretty easy to explain in scientific detail...
Turn on your tube amp and wait for about 30-45 seconds. Hold the palm of your hand up and facing the power section tubes, roughly 4-6 inches away.


Feel that?...tube warmth!!

Remind me of summer 2021 when one my friend, a guitar player, came home to play with me: he used my Traynor YGL-3 and I plugged my bass through an Ampeg V4 and a Traynor YBA-3 (ABY pedal). It was 30 celcius degrees outside with a lot of humidity. Even with the windows opened, it was « too warm » with 12 big bottles cooking!

 

[ThisBass]

Btw some folks might think that a mild "tube like" saturation might naturally generate even order harmonics.
It must be told, this assumption is untrue.

 

[agedhorse]

It’s the even harmonics being added to the signal from driving the tubes.

Generally described as “warm”, “thick”, or “round”.

Also the slight compression with even harmonics slight overdrive as opposed to odd harmonics of solid state.

My experience is that it's IMPOSSIBLE for a tube amp to generate only even ordered harmonics, in fact in terms of energy the harmonics are generally present in roughly equal ratios until you get into very heavy clipping of solid state devices (ie. distortion pedals) which push the harmonic orders higher and tend to favor a higher ratio of odd ordered harmonics.

I think "warmth" is a combination of particular a) EQ characteristics, b) clipping characteristics, and c) compression characteristics, at least where tubes are concerned. "Warmth" more generally can mean different things, to me. Tubes are hard to accurately emulate, and not many have truly done it with solid state electronics. All-tube amps really have their own sound, and even tube hybrid amps (tube preamp, solid state poweramp) don't quite hit the mark, even if it's otherwise a fine amp.

In my experience with tube amps, tube hybrid amps, and solid state tube emulations, the first two characteristics are generally reasonable to emulate in solid state electronics, but tube compression is a much harder effect to nail.

Since each tube amp has its own sound, emulating a tube amp has to start with a particular tube amp first. Tubes are not particularly hard to emulate to a reasonable degree, and IME it's more important to accurately emulate the voicing of the particular amp you are trying to emulate.

Nope, there are even and odds added.
The 2nd may be strongest in context, that's all.

This matches up with my experience too.

 

[Patrice B]

valves are non-linear. What you get out is not an exact (but louder) copy of what you put in. Transistor amps are linear and are a "hi-fi" reproduction of the input signal. In practice, what the non-linearity means is that if you put a sine wave in, you get a deformed sine wave out. Think a pure sine wave that is -5V to +5V. Through an exaggerated valve amp, the first 1V would be the same, the next one would only be 0.9V, the next one 0.8V, then 0.7 then 0.6V. The top of the sine wave is a bit flatter than it should be. That, in a sense, emphasises odd numbered harmonics (so 3x the fundamental, 5x, 7x etc).

When you drive a transistor amp into distortion, you get a sine wave with a flat top and very sharp corners between the sloping sides and the flat top. That adds huge amounts of very high harmonics which can sound harsh unless you have a low pass filter. Valve amps continue with the non-linearity. You eventually get a flat top to the wave form, but with rounded corners between the top and the sides. Tube distortion is less bright and less harsh.

Tube amps can be built targeting the more linear curves of the tubes. I have hifi tube amps from the 60´s with really low THD at rated power. There is quite a difference between MI amps and high fidelity - aka music listening - amps.

As said @agedhorse (I think, not really with these exact words though), an SVT is really clean and detailed unless you crank it a lot.

 

[ThisBass]

@agedhorse (I think, not really with these exact words though), an SVT is really clean and detailed unless you crank it a lot.[/QUOTE]

An SVT amplifier might by anything but clean.
I have got one. a 70's one, and I can tell you, this amplifier is NOT clean in the meaning of HiFi.

 

[Patrice B]

An SVT amplifier might by anything but clean.
I have got one. a 70's one, and I can tell you, this amplifier is NOT clean in the meaning of HiFi.

I should had put the obligatory « IMHO ». For me, it’s clean as I only play in my basement home studio at decent levels. Even tried it with my iTunes library with my YBA-3 to have big stereo sound.

A little 5 watts tube amps cranked to max with my Telecaster is my definition of « not clean »…

 

[agedhorse]

In terms of MI amps, the SVT is pretty darn clean up to close to rated power.

Hi-fi amps looking for very low distortion numbers tend to use some global feedback in the preamp and higher global feedback factors in power amps.

 

[MDBass]

My experience is that it's IMPOSSIBLE for a tube amp to generate only even ordered harmonics, in fact in terms of energy the harmonics are generally present in roughly equal ratios until you get into very heavy clipping of solid state devices (ie. distortion pedals) which push the harmonic orders higher and tend to favor a higher ratio of odd ordered harmonics.




Since each tube amp has its own sound, emulating a tube amp has to start with a particular tube amp first. Tubes are not particularly hard to emulate to a reasonable degree, and IME it's more important to accurately emulate the voicing of the particular amp you are trying to emulate.


This matches up with my experience too.

You’re a wealth of knowledge Andy, and TalkBass is lucky to have you posting here regularly.

I’ll just point out that I never said anything about tube amps only producing even harmonics.

Since even harmonics sound “warm”, and odd harmonics do not, I suspect the answer to “where does ‘tube warmth’ come from” has much more to do with the even harmonics tubes produce than the odd harmonics they also produce.