ModBlog: Tube vs Solid-State Power
Tube vs Solid State Power:
This debate has been around far longer than the twenty-six years ModWright has been in business. It is a valid point of discussion with no right or wrong answer. As with many things audio-related, it’s a matter of physics, design and system synergy.
Many describe tubes as warm, dimensional and musical. Others say that solid-state amps are powerful, controlled and resolving. The fact is all these things are true and correct.
Let’s try to get to the bottom of the debate and separate a few myths from reality…
Myth #1: Tubes Are “More Powerful”
It is commonly said that Tube Watts are more powerful than Solid-State Watts. I understand where this notion comes from, but it is technically incorrect.
People may say: “My 40-watt tube amp sounds louder than my 100-watt solid-state amp.”
This is a matter of perception, not fact. Tube amplifiers clip gently and gradually, so they can be overdriven for short or long intervals, without sounding objectionable. Solid-state amps on the other hand, clip hard and the sound is not pleasant.
A simple visual analogy: tube clipping resembles a gradually stretched bowstring. Solid-state clipping resembles a flat-topped waveform.
When a tube amp clips, additional harmonics are generated and the human ear does not interpret this as objectionable. When a solid-state amp clips, the higher order artifacts sound aggressive and harsh.
So we can see that power is still power. 40W is still 40W, not 100W. If your speakers are not very efficient and your room is large, current delivery and headroom are non-negotiable.
Myth #2: Solid State Is Harsh
Early solid-state designs were modeled after tube circuits, while using transistors. They were designed after a voltage, not a current model and as a result, poor biasing, crossover and current-weak power supplies resulted in sound that was harsh and lacking in musicality.
This is not true of well-designed modern solid-state amplifiers. Current based designs now dominate high end audio solid-state amps and as a result, they now offer the following:
- Lower output impedance
- Higher damping factor
- Greater current delivery
- Stability into difficult loads
- Strong bass control
If a solid-state amp sounds sterile or harsh, that is a design issue, not a device limitation.
So what are the major design differences that set tube and solid-state amps apart?
Tube Amplifiers
Most tube amplifiers:
- Operate at high voltage
- Are output transformer coupled
- Have higher output impedance
- Interact dynamically with speaker load
- Clip gently
Sonically, this can yield:
- Sweet midrange
- Harmonic density
- Organic texture
- Large soundstage and bloom
They also have low damping factors and speaker matching is essential.
A critical point of distinction is that tube amps are Voltage Amplification Devices!
Solid-State Amplifiers
- Operate at lower voltage and higher current
- Have lower output impedance
- Provide great damping factor
- Deliver substantial power into low impedances
- Remain stable under demanding conditions
This typically translates to:
- Tighter, deeper and more resolving bass
- Greater dynamic headroom
- Strong macro-dynamics
- Works well with a broad range of speakers
A critical point of distinction is that solid-state amps are Current Amplification Devices!
It is not a matter of whether Tube or Solid-State amps are better. They are simply different and we all prefer different things.
Distortion Matters:
Tube and Solid-State amps have different distortion artifacts. The way the human ear perceives this difference is key.
While many focus on Total Harmonic Distortion, the distortion spectrum is the critical factor.
Tubes produce predominantly second order and even order distortion harmonics, while solid-state amps produce more odd order and higher order distortion harmonics. This is not hard and fast, and design topology matters a lot here.
It is also true that the amount of Total Harmonic Distortion from solid-state amps is lower, often orders of magnitude lower! This is why many will argue the above point moot. Measurements are invaluable, but they do not yet fully capture how the human ear perceives harmonic structure.
The key to this, is how the human ear perceives the different distortion spectrum.
At ModWright, we design for the Enjoyment of Music.
For listeners who love the dimensionality, body and presence of tubes but want solid-state control and resolution, the KWA MOSFET Monoblock Amplifiers offer the ideal balance.
The use of Exicon Lateral MOSFET in the KWA 99 allows for:
- Body, weight and harmonic richness
- Sweet Midrange
- Musicality and Resolution
- Broad range of speaker compatibility
For larger rooms, difficult loads and more demanding systems, the BJT based KWA 300 Reference Stereo Power Amplifier may be ideal.
Designed around BJT (Bipolar Junction Transistors) and a massive power supply, the KWA 300 delivers:
- High current
- Exceptional Bass control and impact
- Effortless dynamics
- High resolution without strain or harshness
For those who prefer a hybrid / signal-level tube integration:
We offer both the KWH 225i Hybrid Integrated power amp and The Analog Bridge.
A hybrid approach to system design has always been the ModWright way.
Using tubes in line level applications allows for the sonic strengths of tubes:
- Body, weight and dimensionality
- Beautiful midrange
- Big soundstage and live presence
And because we reserve solid-state devices and design topology for the power stage, we still retain the strengths of solid state:
- High current
- Exceptional Bass control and impact
- Effortless dynamics
- High Resolution
Tube character. Solid-state authority. No penalties.
Tube and solid state are different, not opposing, ideologies.
Two approaches with their own strengths. One is not always right for everyone. System synergy is key and each must be assembled with that in mind.
The right choice depends on your speakers, your room, your listening level, and your taste.
- MOSFET liquidity.
- Bipolar authority.
- Tube harmonic integration.
Different approaches. One goal:
To bring you closer to the emotional core of the music.
Elegance. Simplicity. Truth.