Distinctly Different

Recently, my wife and I attended a music showcase. One of the bands featured a very good local guitarist, one that I’ve known of for over 30 years. He’s always played well, and he’s well respected.

During the course of the show, he played several guitar solos, all of them top notch, and kept the rhythm going with style the rest of the time. He was using a Fender® Stratocaster®, which looked to me to be either a 57 re-issue or an Eric Johnson signature model, and a Bugera amplifier, with a well-stocked pedal board in between. This brings me to my first point.

Eric Johnson has a signature tone. If you’ve heard him play, it usually doesn’t take long to discern that, ‘that’s Eric Johnson playing.’ Fender recently introduced a new Eric Johnson Signature Stratocaster Thinline model. While talking about this guitar, Mr. Johnson recalled some advice that B.B. King gave him years ago:

“You know, you can do this; you can do that. There’s all these things you can do, but find the one thing you do that’s unique, that nobody else can do, and just go with it!”

B.B. King had an instantly recognizable style. So does Eric Johnson. So do many others, from Carlos Santana to Willie Nelson to Roy Buchanan.

While listening to this great local guitarist play his solos, which were all on point and very good, I couldn’t help but notice his tone. To me, it sounded very, well, generic. It sounded like a Strat played through a pedal board. Nothing distinguishable about it, even though it was musically very good and well placed.

During a break in the show, my wife, who has a very discerning ear for music, had asked me who the guitarist was, and commented that he was really good. She’s very honest about her musical thoughts. If my tone or playing or singing is not very good, she will tell me. She’ll also honestly tell me her thoughts about anyone we listen to. I value her opinion; it’s an opinion forged by years of musical training.

As we were driving home after the show, I asked my wife what she thought about his tone. I asked her cold, so as not to prejudice her response. She replied that his tone, “wasn’t very good. It sounded cheap.” Interesting, especially considering that he was a very good guitarist playing what is considered to be good equipment.

That One Thing

Perhaps the greatest compliment I’ve ever received from anyone came from Mark Daven of the Guitar Radio Show. During an interview with him, after he had played two guitars through two different Texas Tone™ amplifiers, he stated:

“Many times I’ll play amps and you can’t tell one from the other. These are very distinctly different sounding amps. They made me play differently. I started approaching the instrument in a different way as I played each one.”

Mark Daven, Guitar Radio Show

When speaking about my signature amp, the Texas Tone 12, he stated that it has a “a pulsating tremolo. Different than anything I’ve heard before.”  He’s heard lots.

Don’t be generic. Don’t settle for a ‘me, too’ sound. Take advice from two masters, B.B. King and Eric Johnson. Find that thing you do that’s unique, that nobody else can do, and just go with it.

For me, it’s hand made tube amps, featuring the unique Hypnotic Slam Effect of the  Texas Tone 12 tremolo.

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Low Noise

I’m often asked how it is that my Texas Tone amps have so little hum and hiss compared to many other tube amps, and yet have such sweet tone. It’s by design.

So many tube amps today are descended from amps in the mid-1950s to the mid-1960s. Many builders today make tube amps that are either clones or replicas of those amps. Texas Tone tube guitar amplifiers are not clones or replicas. They are new designs that are inspired by those iconic amps of the past. In those rare cases where we make a traditional amp design, it’s updated for low noise and safe operation.

Why not clones or replicas?

Safety

In some cases, the choice is clear – safety. Guitar amplifiers of the past had two-pronged non-polarized AC plugs. Turning the plug upside down reversed the polarity, which was interesting because there was no way to know which end was up. The danger of this is that the so-called “ground” side of the amp chassis could become “hot” and vice-versa. Tube amp builders made compromises and concessions to this. Two of these were the Ground switch and what became known as the “Death Cap.”

The Ground switch reversed the polarity of the plug (equivalent to turning the plug over, when you didn’t want to turn off your tube amp). I recall that the trick was to get all the amps on stage to the same polarity.  How did we do that?  Hold your guitar strings and tap a microphone. If you got shocked, you needed to flip your Ground switch or turn the AC plug over.  Ouch!

The Death Cap was a capacitor wired to one side of the AC power, or to the Ground polarity switch. It was intended to get rid of hum if your polarity was reversed. The reason it’s called a Death Cap is that if the capacitor fails, then your amp chassis, and by extension your electric guitar, could become hot with 120 Volts AC, a most unpleasant situation. Today, all amplifiers are built with a three-prong AC plug and a power ground, or at least they should be.

Noise

The noise floor of many vintage amps (new ones, too) is quite high. Many guitarists just get used to the noise and hum. I know one who doesn’t like tube amps because they hum and hiss.  I told him, “mine don’t.”  Some guitarists buy noise gates or noise filters or line filters to help reduce unwanted noise and hum. This noise is due to two things – component selection and wire lead dress. A little background may help.

Grounding

Many amps are built with poor grounding techniques, with multiple ground points throughout. This is a recipe for noise, as multiple ground points cause ground loops, a main contributor to noise. Texas Tone amps are built with solid electrical engineering ground scheme to eliminate ground loops and ensure low noise operation.  Well-respected electrical engineer and amp builder Randall Aiken has a nine-point plan for proper grounding.  As he states, “Grounding isn’t rocket science.”  Makes me wonder why some amp builders don’t follow basic grounding rules.

Lead Dress

In the mid-1960s Leo Fender sold his company to a large conglomerate. They immediately instituted cost-savings, partially due backorders of items sold but not yet produced. The Fender General Manager, Forrest White, had implemented a quality bonus program to ensure high quality work, but this was one of the first things scrapped to increase production numbers. Due to the rush to push product out the door, and without the quality incentives, amplifiers were built without proper attention to wire lead routing, called “lead dress”. Poor lead dress can lead to hum, hiss, oscillations, squealing, and generally negative impacts. Rather than fix this, the company changed their circuits to add anti-oscillation components, and changed component types and values to save money. The end results was that guitarists began to seek out the older amps that sounded better.

Components, Wire, and Lead Dress

Texas Tone tube guitar amplifiers are built exclusively with aerospace grade military specification wire. It’s flexible and yet holds its shape, even with right-angle bends, is conservatively rated at 150C (300F) and 600 working volts. I’ve seen some tube amps use 105C or even 85C wire rated as low as 300V. Since most tube amps produce between 300 and 500 Volts DC, using 300V wire is asking for trouble.

I make sure that the wiring inside Texas Tone amps does not induce noise, by ensuring that high voltage wires are kept away from signal wires.  Any time wire paths cross, they do so at right angles and sufficient air space.  Many sensitive signal wires are shielded.  There are lots of current spike and noise in transformer center-tap wires and choke wires.  These are kept away from sensitive preamp nodes.  I’ve seen some amp builders, in the name of neatness, bundle wires together with tie wraps – a sure recipe for noise.

Amps of the 1950s used carbon composition resistors. Why? Because that’s what was available and cheap, not because of some “sound mojo”. Allegedly, and subjectively, carbon comp resistors are said to be somehow warmer sounding.  Huh?  Many of these resistors aren’t even in the signal path!  Carbon comp resistors have notoriously loose tolerances, poor drift and noise characteristics, and are responsible for most of the crackling and frying sounds heard in most old tube amps.  I’ve also tested 220k carbon comp resistors that read anywhere from 185k to 240k!  Not good when the circuit calls for two 220k resistors tied together, or using one as your supply voltage for a gain stage.  Rest assured, the gain and distortion characteristics of a preamp with a 190k versus a 240k are quite different.

Most of these carbon comp resistors are rated at 350 Volts, not a happy situation in tube amps that routinely see more that 400V!  The resistors used in Texas Tone tube guitar amplifiers are known for their stability, high temperature and voltage rating, and extreme low noise, and they don’t drift like carbon comp resistors. Here’s a comparison:

Type Tolerance Temperature Voltage Low-Noise
 Carbon Comp 1/2 Watt  ±10% 125C 350V NO
Texas Tone USA ±1% 175C 500V 0.10 μV/V
Texas Tone 1 Watt ±5% 155C 500V -10x Carbon Comp

Not only are these components low-noise, high voltage, and high temperature, they have tighter tolerances and they don’t drift, so they maintain your sound.  You want your sound to be consistent, night after night, gig after gig, session after session. You want a reliable musical instrument, not one that crackles, pops, hums, and is unreliable.

When you hear a Texas Tone amp, you’re not hearing hum and hiss, you’re hearing yourself at your best!  When you sound your best, you play your best.  Your tone matters.

Fight Marketing BS

I was looking at boutique tube amp websites, since I’m in that business.  I’m looking to see what other builders’ websites look like, what they’re selling, what their prices are, etc.   I’m often amazed by the amount of marketing lingo, and frankly, total BS that can be found on some of these sites.  I will list a few of these.

Period-Correct Transformers

This one is pure BS. Household voltages in the 1950s were perhaps 10 volts lower than they are in 2017.  Therefore, if you take an amplifier built in the 1950s and run it on today’s power, the test/idle voltages, bias numbers, etc., will all be off.  The high voltage may as much as 30 Volts DC above specification.

However, an amp built today is built with transformers designed for 120V operation, so that negates any need for “period-correct transformers.”  As a matter of fact, if a 1957 amplifier uses a 115/650VAC transformer, and a new amp uses a 125/650 volt transformer, guess what- they both put out 650VAC, it’s just that one does it with a 115V input, and another does it with a 125V input.

While it’s true that if you run are using an old amp from the ’50s today your voltages will be too high, a new amp is designed for today’s higher line voltages.  A “Period-correct transformer” only matters if you’re replacing a power transformer in an old amp.  To that end, some of the new replacement transformers have two primary taps.  One example used in my amps has a 115V primary and a 125V primary.  Bear in mind also, that although 120 VAC is the modern U.S. standard, actual measured voltage is plus or minus 5%.  I usually see 122 Volts in my shop.  When I test my amplifiers, I always use a variable AC transformer to test at 120VAC.

Tube vs. Solid-State Rectifiers

I read on one site about an amp’s tube rectifier having excellent sonics due to a lack of solid-state components.  That’s debatable enough, as many guitarists like the sound of their solid state amps, but then he goes on to say that solid-state rectifiers slam the tubes on power-up causing excess tube wear.  That is simply not true!

Tube-rectified amps generally behave differently than solid-state diode rectified amps.  In general, solid-state diode amps are “tighter” than tube-rectified amps, and tube-rectified amps generally exhibit a bit of voltage “sag” under high loads, leading toward a compressed sustain.  Again, in general.  Some people like solid-state rectified amps, and those amps have excellent sonics.  Amps such as a Twin Reverb® of Vibro-King® have solid-state rectifiers and excellent sonics.  My Texas Tone™ Ranger comes with a solid-state rectifier, and can also use a tube rectifier.

Solid-state rectifiers do not “slam the tubes on power-up.”  In fact, the type of rectifier has nothing at all to due with slamming the tubes on power up!  That particular symptom is a function of the Standby switch.  The Twin Reverb® and Vibro-King® use solid-state rectifiers and a Standby switch.  When a Standby switch is used on startup, waiting 15 seconds between turning on the power switch and switching the standby switch on, then there is no slamming the tubes on power-up, regardless of the type of rectifier.

The whole idea of slamming the tubes on power up is debatable anyway.  Books have been written about it.  The official tube manuals speak of things such as “cathode stripping” and the need for standby switches, but add a qualifier, “except for receiving tubes.”  Tubes used in guitar amplifiers are all receiving tubes.  Some tube rectifiers heat up gradually, and don’t even need a Standby switch.  I like to use a Standby switch, and I isolate them for trouble and noise-free operation.

Cathode-Biased Watts

Some boutique amp builders claim that their cathode-biased 6V6 tube amps produce 18-22 Watts with two 6V6 tubes in a Class AB push-pull configuration.  Um, no.  With 350V plate voltage you might get 13 or 14 watts.  If you’re running 420V B+ you might even be able to get to 16 watts.  By the way. the 1955 GE tube data lists 315 V DC maximum for their 6V6GT tube; a modern JJ 6V6S indicates a 500VDC maximum.  Either way, you’re going to be hard-pressed to get more than 16 Watts from any cathode-biased push-pull 6V6 amp, and that’s running way-above-spec (for anything but a JJ 6V6S) plate voltage (some people call the JJ 6v6S a cross between a 6V6 and 6L6).  I don’t know where they’re getting those 18-22 Watt numbers.  Instantaneous millisecond peaks at the speaker with 50% total harmonic distortion?  I don’t know.  I rate my amps in real, tested Watts.  My cathode-biased 6V6 push-pull amps will output around 14 Watts +/- 2W, depending upon the model.  No BS.

Surface-Mounted Components

One builder claimed a “surface mount capacitor” as the main power supply filtering device.  Huh?  Then he includes a photo and the model of the capacitor.  It’s not a surface-mount capacitor. It’s a multi-section can electrolytic capacitor, the same one used in hundreds of other amplifiers.

These are surface-mount capacitors, not used for power supply filtering in tube amps (they’re tiny, smaller than a dime):

surface-mount

This are multi-section can, of the type used in tube amps (they’re about the size of D cell batteries):

nice

Point-to-Point Wiring

Don’t get me started.  I wrote a whole blog on this.  I do not use “point-to-point’ wiring.  With point-to-point wiring, each component is connected to a tube pin or solder lug or jack.  There are no “boards” whatsoever.  Examples of this style of construction include most old tube hi-fi equipment, 70-era Sunns, and more recently BadCat and Carr.  I sturdily mount all passive components on turret boards or tag boards.  Wires are carefully routed to avoid noise and cross-talk, and I color-code all wiring for easy tracing.

True point-to-point wiring example:

point_to_point_thumb.jpg

Turret board wiring example:

LilDawg12_thumb.jpg

I looked inside one award-winning boutique amplifier advertising 100% true point-to-point wiring.  He is correct, and it’s a mess inside, with gobs of silicone holding everything in place and wires and components everywhere.  On the other hand, I see other builders that seem to be neat-freaks, with wires tied together in bundles, which is a recipe for noise.   Neatness counts, but neatness in correct wire dress, not looks. Substance over flash is one of my values.

It matters not whether an amp uses a PC board, tag board, turret board or true point-to-point wiring.  What matters is whether the components are sturdily mounted and selected for long life, laid out logically, and that signal, power, and heater pathways are routed for low noise and easy troubleshooting, and that you tell the truth about your amps.  Rest assured that all of these criteria are met in Texas Tone™ amps.  In many cases, the hiss is so low that you have to play your guitar to verify that the amp is turned on. It’s why power lights are so important!

Be aware

Don’t fall for marketing BS.  Don’t just buy an amplifier because your guitar hero plays one.  Do you play and sound exactly like your guitar hero?  If not, then using the same guitar and amp won’t make you sound like him.  I can play with a Twin and a 335, and I still don’t sound like BB King, nor if I use a Strat and a Marshall stack will I sound like Hendrix.

If you want a reliable amplifier, with high quality components, low-noise and easy troubleshooting wire routing, and above all great tone with no BS, chose Texas Tone™. Why? Because “Your TONE Matters”.

Your.Tone.Matters.07

I’m not going to lie to you or trick you into buying one of my amps with marketing lingo.

Thanks.

Inspiration

What does “Inspired By” mean?

Vintage amps sound great, or do they? Unless you’re a professional or collector with the means to pay for one, you’ll probably never know, except when you hear someone else play one. You may never hear one, as people that own them often don’t tour with them, because they’re too valuable, or fragile.

One thing is certain. They’re old. They have outdated grounding schemes that are noisy. They have capacitors that have dried out. They have resistors that have drifted from their original specs. It may sound good, or it may not.

So people buy clones. Sometimes they pay large sums for a factory “reissue.” But, what is it that you really want from a good tube amp?

Before you decide, know what you really want.

Sometimes, the most difficult thing to ascertain when making a decision, is, what is the desired outcome, what is the goal? Is the goal to have a 5E3 Deluxe, a 5F6a Bassman, or a JTM45? Why? Because they’re great amp? They were great amps. They’re iconic. They’re the standard.

Many times, though I hear from guitarist questions or complaints about these designs. Things such as,

  • “How can I get more clean headroom from my tweed Deluxe?”
  • “My Bassman/Marshall clone is too loud for the venues I play. I have to turn it down, and then I don’t get the tone I want.”
  • “The amp is great, but it’s heavy” or “it’s too noisy.”

Inspiration

Texas Tone™ tube guitar amplifiers are inspired by famous designs.

The Texas Tone 30 is inspired by the 5F6a Bassman/Marshall JTM45. But it’s not a clone of either one.

  1. I dispense with the Bright channel, and add a Lead channel. Why? The Bright channel simply had a high-pass capacitor that bypassed high frequencies around the Volume control. My Lead channel actually changes the gain and frequency response of the channel, allowing for both more distortion and a better ability to take pedals.
  2. The resistors are chosen for low-noise, stability, and long life.
  3. Modern grounding techniques allow for less hum and hiss.
  4. I use a phase inverter that is more balanced and still high gain, and a different output transformer, to push the output tubes to optimal performance.
  5. I scale back the Presence control with a more subtle Voicing control.

The results is a loud 30 Watt 12″ combo amp that can play with sweetness or crunch. I call it my BB King amp, because with it, even I can get those sweet tones.

The Texas Tone Ranger is inspired by the Marshall 18W amp, but it’s not a clone, or even close. For starters, it uses a pair of cathode-biased 6L6 output tubes for the full-range tone those tube are famous for, rather than the EL84 tubes of the Marshall. Secondly, I use the ‘normal’ channel as a practice channel, with less volume and a single non-interactive tone control that is a high-pass/low-pass design, rather than a simple treble roll-off. The TMB channel is a rocker.

Inspiring Better Living through Better Tone

It’s my experience that when you have better tone, you’re inspired to play more, to play better. I once told a band mate that if you have the right tone, you can play anything. Think of your favorite guitarists. Chances are, he has a signature style, a signature sound, a signature tone.

Inspire yourself. Go practice. Sound good and be heard.

Cheers.

Please, Not Another Clone!

There are a handful of famous tube guitar amplifiers: Fender tweed Deluxe and Bassman; Marshall JTM45; Vox AC30; Fender Deluxe Reverb and Twin Reverb. They’re considered icons, the best of their breed. I don’t build clones of those amps – who needs another tweed Bassman? Modern solid-state amplifiers make use of modeling or digital technology more on that later and can be made for low-cost overseas and offer a wide variety of features, but none have attained the icon status of the great amps of the 1950s and ’60s.

“Hollow-state” technology is non-linear in its response, i.e. how a preamp tube responds- in frequency response, dynamic range, distortion, and amplification -varies depending upon the instantaneous input signal. When you realize that live electric guitar signals are nothing like the waveform-generated signals of a workbench, you also can visualize why creating a musical signal that can replicate this instantaneous harmonic distortion and non-linear response is quite unrealistic, and must depend upon approximations and false assumptions. A modeling amp can sound “sorta” like a vintage amp, at least until you play it side-by-side with a real vintage amp under real live musical situations.

The tube amplifiers that I build are designed to re-introduce these vintage circuit characteristics and combine them with modern quality components, build techniques, grounding techniques, and electrical principles to produce a guitar amplifier that creates a new sound that still seems “vintage” in quality. While I might base my designs around the tweed amps circuits, compared to them I utilize a preamp that operates under higher clean headroom conditions, which both provides a means of highlighting output distortion and makes my amps very pedal friendly, something that wasn’t even considered in the late 1950s or early ’60s. Changes such as voltage and filtering levels, and a low TSR index create a larger input dynamic ranges, reduced third order harmonics and wider input dynamic range at the phase splitter. The resulting sound is what you expect from a hand-built tube guitar amplifier- sweet, dynamic, touch sensitive tones that make your guitar sing.

While my amps are not clones, they’re certainly inspired by those great amps, but with a few good modern touches, all built by hand in Austin, Texas. Maybe that’s why one happy owner recently replaced his famous British amp with a Texas Tone 12.

TexasToneJSB

Better Living Through Better Tone.

-Texas Tone tube guitar amplifiers.

Why Re-invent the Wheel?

When discussion turns to new amps designs, the phrase, “Why re-invent the wheel?” often comes up in the conversation.  I heard it twice at the 2015 4 Amigos Guitar Show in Arlington.  This is usually accompanied by a discussion of the iconic, Holy Grail amps of the mid-1950s to mid-1960s, especially the Fender blackface “Reverb-Amp” designs, the Fender tweed Deluxe, and the tweed Bassman, a design which was also the basis for the iconic Marshall JTM45 amp.  A well-known website for finding amplifier schematics actually links to the Bassman schematic as the JTM45 schematic.

With these three amps being considered the epitome of tube guitar amp design and implementation, do we really need new or even different amp designs?  Do we need to re-invent the wheel?

Leo Fender’s preamp.

Leo Fender’s guitar amplifiers set the standard for guitar amps.  Not only are his tweed Deluxe and Bassman amps considered all-time classics, his black-faced Deluxe Reverb and Twin Reverb amps are also classics, the amps by which others are judged.  All of these amps, including clones and reissues, are widely used today.  The same can be said of the famous Marshall Amp designs.

Although today’s guitarists appreciate those tweed amps for their sweet sustain and creamy, compressed distortion, Mr. Fender didn’t intend for them to be distortion machines.  Looking at the evolution from tweed to blackface amps, one can see that Leo Fender was on a quest for more clean headroom, which is what the Twin Reverb is all about – clean and loud.

1959FenderTweedDeluxe-058

Throughout his changes in circuit designs, power, voltage, and headroom, one thing remained fairly constant over 15 years – his 1st stage preamp design.  Leo certainly didn’t re-invent the wheel.  He used stock Western Electric circuits right out of tube manuals, and even paid licensing fees to Ma Bell (AT&T).  In fact, the component values for the little-to-no clean headroom tweed Deluxe and the lots-of-clean-headroom Twin, are essentially identical.  The 100kΩ load/plate resistor, the 25µF cathode bypass capacitor, and a 1.5kΩ to 1.6kΩ cathode resistor.  How does that work?

1st_stage_preamp

The only difference between the 1st stage preamp design on a tweed Deluxe and a blackface Deluxe or Twin is that the tweed amps used a lower gain 12AY7 and the blackface amps used a higher gain 12AX7.  Oh, and one more thing.  Higher DC supply voltage, especially on the Twin.  A tweed Pro preamp had a supply voltage of 250V, while the Twin had 410V!  All other things being equal, more supply voltage lends to more clean headroom.  For example, the 1st 12AX7 in a blackface Deluxe Reverb idles at about -1.3V bias voltage, while in a blackface Twin, this same tube idles at about -2V bias.  That extra -0.7 Volts is an indicator of how much more signal the tube can take before it saturates, 1.4 Volts peak-to-peak (-0.7 x 2) – that’s the extra clean headroom.

This higher voltage rule of thumb also applies to the power tubes, by the way.  All up to a point, of course.  There is such a thing as too much voltage or current, and the key here is “all other things being equal.”  When the values of Ra, Ck, and Rk are the same in a tweed Deluxe and a black faced Twin, the supply voltage becomes the big difference.

So, why reinvent the wheel?

Some people don’t want the crunchy distortion of a tweed Deluxe, or the clean and loud of the Twin Reverb. They may not like the higher noise floor of the tweed amps for when they’re recording.  There are any number of compromises, cons, and drawbacks to any amp.  There are other ways to get clean headroom and smooth distortion characteristics besides higher voltages, including the choice of cathode resistors. Even though the 5F6a tweed Bassman and the JTM45 Marshall share the same circuit diagram, we find that Marshall Amp voltages, and preamp cathode resistor and capacitor values, are quite different than Fender’s, as are the tubes used, and the tone stack component values, all of which help account for the different sound of Marshall amps compared to Fenders.

When I designed the Texas 2:10 special, it was for a friend who played a tweed Bassman clone in small clubs.  It was too loud for him; he couldn’t hit that tube amp “sweet spot” at the low volumes required in these clubs, so he resorted to using boost pedals to get the tone he wanted.  What did I accomplish with the design?  I built an amp with almost no circuit noise that can go from clean to dirty at reasonable volume levels.  An amp that can go from the “scooped Mid” feel of blackface clean to a punchy midrange grit, all without being too loud for small clubs or studio use.

It’s not the end all of guitar amps.  It’s just really good at what it does.  I’m pleased by all the positive reviews I’m getting on it, words such as “amazingly impressive”, “the best amp at the show”, “coolest amps I have ever seen” and “the crisp cleans, and crunchy punch and pop that I’m always looking for.”

Thanks for all the kind words.

-Bruce

Why Do Tube Amps Sound Better… or Do They?

Many guitarists, especially those that play rock, blues, or country music, seem to agree that “tube amps sound better”.  Almost all guitarists would agree that given the same rated output power, that “tube amps sound louder”.  A 30W amp tends to sound louder than a 65W solid state amp.  Of course, for some types of music, solid state is the preferred amp, and it’s for very reasons that tube and solid state amps sound different.   A jazz guitarist who is not going to overdrive his amp may like the cleans that solid state amps offers.  A metal guitarist or “shredder” may like the very overdriven tones that solid state amps produce that make them so very different than tube amps.

Why do so many think tubes sound better?  I am one of them.

Here’s why:

Guitar amplifiers are often severely overloaded by signal transients, (THD 30%), especially in today’s world of high output pickups and pedals. Under this condition there is a major difference in the harmonic distortion components of the amplified signal, with tubes, transistors, and op-amps separating in distinct groups.

Op-amps produce strong third, fifth, and seventh harmonics when driven only a few dB into overload.  The resulting sound is metallic with a very harsh edge, which the ear hears as strong distortion. Because the sound may be objectionable, op-amps are rarely operated in their saturated region.  This results in a very clean amplified sound with little coloration and true dynamic range (within the limits of the amp).  This dynamic range is not necessarily a good thing, because of the limits of the rest of the system.  The top end of the dynamic range contains transients, but lacks solid pitch information.  The result?  Clean, but perhaps sibilant and cymbally.  Colorless.  Dull.  Perhaps you don’t want your amp to “color” your sound.

Transistors produce buzz or white noise when severely overloaded, caused by the edge produced by overloading on transients, mostly seventh and ninth harmonics. The ears hear this dissonance as noise. Another factor is a lack of “punch” due to strong third harmonics, a kind of blanketing of the sound. Transistor amps exhibit a strong third harmonic when driven to overload, producing that blanketed sound.  This sound, compressed lack of punch, and strong odd order harmonics, may be what some guitarists are looking for.

Tubes generate a whole spectrum of harmonics when overloaded, particularly the second, third, fourth, and fifth, to give a very full bodied sound.  Tubes also differ from op-amps and transistors in that they can be operated in the overload region without adding objectionable distortion.  A slow rising edge and open harmonics combine to create an ideal sound.  Within the 15-20 dB overload range, the electrical output of the tube increases only 2-4 dB, creating a natural compression.  Since the edge is increasing within this range, the subjective loudness remains uncompressed to the ear.  It is this effect cause tube amps to have a higher apparent volume level not indicated on a volume (VU) meter.

Tubes sound louder and have a better signal-to-noise ratio because of the extra subjective headroom that transistor amplifiers do not have.  Tubes get their punch from their natural overload characteristics.  Since loud signals can be reproduced at higher levels, the softer signals are also louder.  This is the famous “sweet spot” that tube amps exhibit.  Strong second and third harmonics give a feeling of a more natural bass response.

The sweet spot will sound loud clean and full, and exhibit wonderful touch sensitive dynamics that follow the guitarist’s playing dynamics.  Roll back the volume control on the guitar or play softer, and you get the full, rich tone at a quieter level.  Dig in, or roll up the volume control, and now you have that natural, sweet, singing tube overdrive that we love so much as guitarists.  This is why we love tube amps!

Notes on harmonics. The primary color characteristics of an instrument are determined by the strength of the first few harmonics.

  • Odd harmonics (3rd and 5th) produce a stopped or covered sound.
  • Even harmonics (2nd, 4th, & 6th) produce choral or singing sounds.

The second and third harmonics are the most important.  The second, an octave above the fundamental, adds body and makes the note sound fuller.  The third harmonic is a musical 12th.  Instead of making the sound fuller, it blankets the sound and makes it sound softer.  Adding a fifth harmonic to a strong third gives the sound a metallic quality that gets increasingly annoying as the volume increases.  A strong second with a strong fifth tends to open up the covered effect that the third induces (this is usually what we want).  Adding fourth and fifth to this will change the sound to an open horn like sound.

Higher harmonics, above the seventh, give edge or bite to the sound.  As long as this edge is balanced, it will reinforce the fundamental and give a sharper attack quality.  Too much of the higher harmonics- seventh, ninth, eleventh – will give that raspy, dissonant kind of sound.  The human ear is sensitive to the edge harmonics.

The major characteristic of tube amps is the presence of strong second and third harmonics, sometimes in concert with the fourth and fifth.  Remember, a strong second with a strong fifth tends to open up the covered effect that the third induces, and strong second and fourth harmonics help create that singing sound we all love so much in our tube amps.