Vacuum Tubes Vs. Solid-State. Up Your Production Skills.

Discussion in 'AudioSex Academy' started by Introninja, Jan 14, 2018.

  1. Introninja

    Introninja Moderator Staff Member

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    I modified the original article with updated links & formatting, this is a must read for those who don't fully understand the difference or has never work with hardware that contain Tubes (Manley VOXBOX) & Transistors (API The Channel Strip) Solid State.

    No Shootouts Necessary, but i plan to get members involved, as i don't have access to every product such as UAD, Slate, Aqua, Antelope & Steinberg, but for now i wanna teach you the fundamentals before the fun start (see what i did there lol).

    If your interested please PM me, you can be anonymous in this series if needed, your help would be greatly appreciated. The series will be called Audiosex Ingredients of TONES (A.I.T.) and the chains version will be called Audiosex Kitchen of Recipes (AKR) Patent-Pending, which will be hosted in the preset/patches Sub-Forum and our primary focus will be Strictly Tones. The is gonna up your Production game.

    No gimmicks!!!. I will be releasing my technique how i master nebula and the tools i used to create my OWN CUSTOM GUI's bridging the gap closer between the hardware and software when it comes to Tones & Texture, with the help of third-party libraries & Vsts. Also blending of different libraries/Vsts to create new tone that Acqua Technology/Slate has reserved until now. As y'all already know, my Tutorials don't play and super wicked to understand (hopefully lol) but enough about all that Jazz let's start from the Noise Floor Until Distortion......

    The tube versus transistor debates that you hear most often occur in the pages of consumer and music magazines, with descriptive, but imprecise language like “warm”, “liquid”, “smooth”, and “dynamic”.

    But what do the engineers who actually design the equipment think about tubes versus transistors in terms of objective science and measurements?

    The two professional societies that have the most to say on this subject are the IEEE (Institute of Electrical and Electronics Engineers) and the AES (Audio Engineering Society). Both of these professional societies publish peer-reviewed journals, with articles written by engineers and scientists who work in the professional and consumer audio industry, as well as in cutting-edge academic research. If you are seeking a balanced view on this debate, direct yourself to either or both of these societies.

    Below we point you to some readily available IEEE and AES publications that will help you better understand the differences between solid-state and vacuum tube electronics, their performance, and ultimately their sound.

    IEEE - The Cool Sound of Tubes

    The IEEE published “The Cool Sound of Tubes” in their August 1998 issue of IEEE Spectrum. In the same article, there is also a useful sidebar on tube versus transistor distortion. Finally, there is a useful table summarizing the advantages and disadvantages of tubes and transistors from both sonic and design points of view. Since the table is only available as a graphic image, we transcribe the text from the summary table below while highlighting some of the key points that directly impact sound quality:


    Vacuum tubes – Advantages
    • Highly linear without negative feedback, specially some small-signal types
    • Clipping is smooth, which is widely considered more musical than transistors
    • Tolerant of overloads and voltage spikes
    • Characteristics highly independent of temperature, greatly simplifies biasing
    • Wider dynamic range than typical transistor circuits, thanks to higher operating voltages
    • Device capacitance vary only slightly with signal voltages
    • Capacitive coupling can be done with low-value, high-quality film capacitors
    • Circuit designs tend to be simpler than semiconductor equivalents
    • Operation is usually in Class A or AB, which minimizes crossover distortion
    • Output transformer in power amp protects speaker from tube failure
    • Maintenance tends to be easier because user can replace tubes

    Vacuum tubes – Disadvantages
    • Bulky, hence less suitable for portable products
    • High operating voltages required
    • High power consumption, needs heater supply
    • Generate lots of waste heat
    • Lower power efficiency than transistors in small-signal circuits
    • Low-cost glass tubes are physically fragile
    • More prone to micro-phonics than semiconductors, especially in low-level stages
    • Cathode electron-emitting materials are used up in operation, resulting in shorter lifetimes (typically 1-5 years for power tubes)
    • High-impedance devices that usually need a matching transformer for low impedance loads, like speakers
    • Usually higher cost than equivalent transistors


    Transistors – Advantages
    • Usually lower cost than tubes, especially in small-signal circuits
    • Smaller than equivalent tubes
    • Can be combined in one die to make integrated circuit
    • Lower power consumption than equivalent tubes, especially in small-signal circuits
    • Less waste heat than equivalent tubes
    • Can operate on low-voltage supplies, greater safety, lower component costs, smaller clearances
    • Matching transformers not required for low-impedance loads
    • Usually more physical ruggedness than tubes (depends on chassis construction)

    Transistors – Disadvantages
    • Tendency toward higher distortion than equivalent tubes
    • Complex circuits and considerable negative feedback required for low distortion
    • Sharp clipping, in a manner widely considered non-musical, due to considerable negative feedback commonly used
    • Device capacitances tend to vary with applied voltages
    • Large unit-to-unit variations in key parameters, such as gain and threshold voltage
    • Stored-charge effects add signal delay, which complicates high-frequency and feedback amplifier design
    • Device parameters vary considerably with temperature, complicating biasing and raising the possibility of thermal runaway
    • Cooling is less efficient than with tubes, because lower operating temperature is required for reliability
    • Power MOSFETs have high input capacitances that very with voltage
    • Class B totem-pole circuits are common, which can result in crossover distortion
    • Less tolerant of overloads and voltage spikes than tubes
    • Nearly all transistor power amplifiers have directly-coupled outputs and can damage speakers, even with active protection
    • Capacitive coupling usually requires high-value electrolytic capacitors, which give inferior performance at audio-frequency extremes
    • Greater tendency to pick up radio frequency interference, due to rectification by low-voltage diode junctions or slew-rate effects
    • Maintenance more difficult; devices are not easily replaced by user
    • Older transistors and ICs often unavailable after 20 years, making replacement difficult or impossible


    AES - Tubes versus Transistors: Is There An Audible Difference

    The AES (Audio Engineering Society) published the a journal article in May 1973 titled "Tubes versus Transistors: Is There An Audible Difference" or History of The Mic Preamps to that focuses primarily on the distortion aspects of tubes versus transistors.

    One of the more interesting quotes from the AES article:

    “Our extensive checking has indicated only two areas where vacuum-tube circuitry makes a definite audible difference in the sound quality: microphone preamplifiers and power amplifiers driving speakers or disc cutters. Both are applications where there is a mechanical-electrical interface.”​

    In addition to speakers, disc cutters and microphones we can include phono cartridges and musical instrument pick-ups (ie. guitars) in the world of mechanical-electrical interfaces where tubes have an advantage.

    For impatient readers, skip to the section titled DISTORTION CHARACTERISTICS OF PREAMPLIFIERS, as this section covers the more relevant aspects of tube versus transistor sound.

    This AES article dispels the myth that tubes overload more gently than transistors. This conclusion is reached by comparing variations in the slopes of the distortion characteristics (THD) for silicon transistors, pentodes and triodes. The finding is that there is little variation in how the transistors and vacuum tubes overload. However, there is a difference when they overload. Specifically:

    “Overloading an operational amplifier produces such steeply rising edge harmonics that they become objectionable within a 5-dB range. Transistors extend this overload range to about 10 dB and tubes widen it to 20 dB or more.”

    In the tests conducted for the AES journal article:

    “Further listening revealed that it was only in the range of early overload where the amplifiers differed appreciably in sound quality. Once the amplifiers were well into the distortion region, they all sounded alike -- distorted. In their normal non-overload range all three amplifiers [transistor, hybrid op-amp, and vacuum-tube triode] sounded very clean.”

    and

    “Engineering studios show that any amplifier adds distortion as soon as the overload point is reached. The tests show that all amplifiers could be overloaded to a certain degree without this distortion becoming noticeable. It may be concluded that these inaudible harmonics in the early overload condition might very well be causing the difference in sound coloration between tubes and transistors.”

    The article then digs deeper into the perceived “sound” of the relative distortion harmonics of tubes versus transistors. It was found that:

    “There is a close parallel here between electronic distortion and musical tone coloration that is the real key to why tubes and transistors sound different.”​

    Further reading explains in detail the effects that harmonics have on sound coloration:


    " The primary color characteristic of an instrument is determined by the strength of the first few harmonics. … The odd harmonics (third and fifth) produce a "stopped" or "covered" sound. The even harmonics (second, fourth, and sixth) produce "choral" or "singing" sounds. The second and third harmonics are the most important from the viewpoint of the electronic distortion graphs in the previous section. Musically the second is an octave above the fundamental and is almost inaudible; yet it adds body to the sound, making it fuller. The third is termed quint or musical twelfth. It produces a sound many musicians refer to as "blanketed." Instead of making the tone fuller, a strong third actually gives the sound a metallic quality that gets annoying in character as its amplitude increases. A strong second with a strong third tends to open the "covered" effect. Adding the fourth and fifth to this changes the sound to an "open horn" like character. "


    " The higher harmonics, above the seventh, give the tone "edge" or "bite." Provided the edge is balanced to the basic musical tone, it tends to reinforce the fundamental, giving the sound a sharp attack quality. Many of the edge harmonics are musically unrelated pitches such as the seventh, ninth, and eleventh. Therefore, too much edge can produce a raspy dissonant quality. Since the ear seems very sensitive to the edge harmonics, controlling their amplitude is of paramount importance."

    The last section, RELATIONSHIP OF FACTORS AND FINDINGS, ties everything together. The final paragraph sums it up best:

    “Vacuum-tube amplifiers differ from transistor and operational amplifiers because they can be operated in the overload region without adding objectionable distortion. The combination of the slow rising edge and the open harmonic structure of the overload characteristics form an almost ideal sound- recording compressor. Within the 15-20 dB "safe" overload range, the electrical output of the tube amplifier increases by only 2-4 dB, acting like a limiter. However, since the edge is increasing within this range, the subjective loudness remains uncompressed to the ear. This effect causes tube-amplified signals to have a high apparent level, which is not indicated on a volume indicator (VU meter).

    Tubes sound louder and have a better signal-to-noise ratio because of this extra subjective headroom that transistor amplifiers do not have. Tubes get punch from their naturally brassy overload characteristics. Since the loud signals can be recorded at higher levels, the softer signals are also louder, so they are not lost in tape hiss and they effectively give the tube sound greater clarity. The feeling of more bass response is directly related to the strong second and third harmonic components, which reinforce the "natural" bass with "synthetic" bass [5]. In the context of a limited dynamic range system like the phonograph, recordings made with vacuum-tube preamplifiers will have more apparent level and a greater signal to system noise ratio than recordings made with transistors or operational amplifiers.”

    When playing back early 78 RPM (shellac) disc recordings through a tube phono stage like the Wavestream Kinetics Archival Phono Stage, you will notice a different dynamic character because of the above tube response and dynamics. Subtle artist intonations are clearer and more pronounced, fostering a greater sense of realism and emotional connection to the recording.
     
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  3. Introninja

    Introninja Moderator Staff Member

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    Any opinions on this subject?. Or was it just to much to consume, or maybe your just craving sound samples lol
     
  4. metaller

    metaller Platinum Record

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  5. Introninja

    Introninja Moderator Staff Member

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  6. No Avenger

    No Avenger Audiosexual

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    My first thought: close to too long, but I did read. :yes:

    I looove sound samples. If you can provide some :like: :like: :like:.
     
  7. No Avenger

    No Avenger Audiosexual

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    Some time ago I watched a video with a blind comparison between tube, solid state and soft emu for guitar sounds and except in one case I always liked the solid state best.
     
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  8. Satai

    Satai Platinum Record

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    I like the solid state crammed sound especially in electronica, something to that sound that can't be gotten with tubes. IMHO both are worth giving some love to.
     
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  9. Fudsey Plange

    Fudsey Plange Rock Star

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    [​IMG]

    Jim Marshall
     
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  10. Herr Durr

    Herr Durr Audiosexual

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    after years of stale boring solid state on guitars , I finally went big time tube and got a blues deville reissue...
    more balls than a bowling alley... I have a smaller tube practice amp that breaks up nicely at lower volume...

    at this point I just want to get the solid state stuff out of the way... do agree it's quite acceptable for metal,
    but tube will always add that little something special to the sound... good suggestion about the end of the chain @Introninja

    Have you seen any blind tests where someone can consistently tell the difference
    between tube processed sound and ss? I'm not sure my ears are golden enough to nail
    something like that.. but there is most definitely a difference that's not trivial
     
    Last edited: Jan 16, 2018
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  11. superliquidsunshine

    superliquidsunshine Audiosexual

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    For me and what creams my ears, a tube circuit guitar amp does that for me. It has been a Vox thing these last few years, I have one big and one small practice amp. As mic preamps go, there is room for both. I wish a Sebatron piece and am using solid state currently.
     
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  12. fiction

    fiction Platinum Record

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    I have been reading about this subject years ago, and my conclusion was that tube behaviour can so often be emulated by the right choice of both the combination of bipolar and FET transistors as well as the appropriate circuitry. I have never considered tube amps on the consumer side because the amount of people using them are negligible.
    FET often don't match Tube amp behaviour because
    A) The designer prefers to avoid high voltages in the circuit for various reasons
    B) High-voltage MOSFETs optimized for analog audio instead of low-loss switching applications are quite uncommon because most power supply and switching circuits require fast switching time and low on-resistance both leading to higher efficiency and less heat.

    Nonetheless, it's possible to get closer to tube behaviour than most consumers will be able to identify even in A/B testing.
    This article summarizes quite well what I think about the subject:
    http://www.electronicdesign.com/ana...ate-audio-amps-last-word-or-house-fire-part-2
     
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  13. Blorg

    Blorg Producer

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    Me too. They gotta be old, too -- pre-CBS for Fenders, metal switches for Marshes. Why? Voodoo grigri. That's my story and I'm sticking to it.
    [​IMG]
    Neil Young's main rig, '59 Deluxe. Box on top just turns its knobs :)
     
  14. Cav Emp

    Cav Emp Audiosexual

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    I skimmed that WHOLE post for samples and didn't find a single one.

    I'm not mad, I'm just disappointed
     
  15. Seedz

    Seedz Rock Star

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    imho a geeetar is only half an instrument without tubes, you need em before it'll start talkin' to ya.
     
  16. Fudsey Plange

    Fudsey Plange Rock Star

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    Introninja mentioned this...

    [​IMG]

    What you have to understand about this unit is that it engages the compressor before the preamp.

    The knob marked GAIN controls the drive on the negative feedback circuit in the tube preamp, such that at the setting shown, it generates as close to pure uncoloured amplification as the tube can allow. Upping the gain drives the tube into marginally stronger odd-harmonic distortion, making the sound sharper, zazzier and brighter, lowering the GAIN drives the tube into marginally stronger even harmonic dostortion, making the sound warmer, rounder and richer. That's the essential ability of this preamping unit, to allow you to select the kind of marginal distortion you get, when driving the INPUT level. It is magical beyond words on a voice. Using the warmth on bass guitars is to die for, and running a good synth into this, you have a myriad of interpretations of whatever your core signal is.

    Transistors tend to distort into odd harmonics, because the circuit designs that cause that, are so much cheaper and easier to build than designs that go even.

    People think tubes mean warm. They don't, they mean easy to build, value-for money devices that react with a degree of organic feel and sound great when you push them into distortion. Transistor circuits often just go hard and harsh. That's a circuit design effect, not an intrinsic quality. That's why setting the VOXBOX is more like cracking the combination on a safe, and less like twiddling the knobs a bit till it sounds good.

    But hey, it's whatever floats yer boat innit.
     
  17. Blorg

    Blorg Producer

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    A common/simple guitar amp mod. Add a high-value (250k to 1meg) pot in series with circled resistor. Or simply snip the wire, you might like it. Gobs of extra gain & noise.
    [​IMG]
    Not quite. Transistors, like tubes, can be thrown together in many different ways (different circuit topologies), each with unique saturation/distortion profiles.
     
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  18. Introninja

    Introninja Moderator Staff Member

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    How Mullard Tubes were made, Loving the old school manufacturing practices & procedures
     
  19. Herr Durr

    Herr Durr Audiosexual

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    4 Grand for the real deal... it makes me drool tho
     
  20. GreatJobChamp

    GreatJobChamp Producer

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    THIS!!

    The post of the century.... absolutely astounding information here.
     
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  21. Fudsey Plange

    Fudsey Plange Rock Star

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    There's always the UAD unreal deal. Very, very tasty.
     
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