The Closest You Can Get to Analog Recording Without Winding Tape

Guitar Amps: Tu-be Or Not Tu-be

“Whether ’tis nobler in the mind to gig with a tube amp or a solid-state guitar amp and suffer the slings and arrows of capacitor-sniffing tone snobs”

It’s pretty much a given that your more militant guitar tonemeisters prefer tube amps to solid state. According to Professor Alexander Dumble of Dumble* amps fame, “The fragile harmonics live better in tubes than the crystal lattice of transistors.”

To us mere mortals, the simple truth is that the main difference between tubes and transistors lies in their behavior as amplitude increases. Tubes distort gradually with volume exhibiting a natural compression, whereas transistors perform consistently at increasing volume until they go into distortion. When a transistor clips, it chops off the top of the wave (and throws it to the floor rather harshly), which is very unpleasant sounding. Of the two, tube distortion is much more natural and pleasing to our ears. Tubes distort in much the same way our voices do when we go from talking loudly, to a yell, to a scream. Solid-state amps can scream without distorting, but when they do distort, they lose their voice, in a manner of speaking.

Warmest Regards

Perhaps the biggest misconception in analog circuit design is that tubes sound inherently warmer than solid state. In truth, transformers are more responsible for the warmth of a sound than tubes. In fact, solid-state devices can sound quite warm, depending on the circuit topology surrounding them (think Neve 1073). However, when it comes to distortion, cranking a tube amp gives us the “right” sound for guitars. Tube designs sound better to us because there are fewer components in the signal path than solid state. Of course, the number of components in the signal path is more important when using a solid-state device for recording as opposed to instrument amplification. A transformerless solid-state preamp is as transparent as it gets. Transformerless tube designs are expensive and very hard to do.

The Right Amp for the Job

The type of amp you prefer has a lot to do with your style of music. Certain types of metal and thrash, particularly fast playing, seem to do better with tube amps, where high volume is the order of the day, and distortion comes from the tubes themselves. On the other side of the musical spectrum, jazz works well with solid-state amps, especially if you want your clean tones to stay clean regardless of how much harder you may attack the strings (tubes will distort with heavier attacks). The solid-state Roland JC-120 Jazz Chorus became the de facto jazz amp starting in the mid ’70s. Again, it’s a point of personal preference.

In a choice between a tube and solid-state guitar amp, apart from the style of music you play, the major consideration is whether you’re gigging or recording. The harmonic richness of tube amps is generally preferred in the studio, where the goal is the illusion of larger-than-life sound. The advantage of solid-state amps rests mainly in live performance. They’re lighter in weight (easier to carry to a gig) and not subject to vibration damage in transport the way that tube amps are. They also don’t require any warm-up time, so if you’re late to a gig, you can just plug in and play. This is of particular note if you’re gigging in the winter and your tube amp is in the back of a pickup, or left in a van overnight. Tubes respond poorly to having their heaters lit when they’re freezing cold.

FX Math: Analog Plus Digital Effects, Carry the One, Cancel the Tubes

Unless your effects setup is all analog, or a pricey rack unit (such as Eventide’s Eclipse) patched in through an effects loop, playing a gig with a tube amp can be an exercise in diminishing returns if you’re using one of the prosumer digital multi-effects pedals between your guitar and the amp’s input. Apart from the digital processor taking all the depth out of your tube amp (try an A/B comparison if you don’t believe it), you’d be better off with the high-gain-before-clipping response of solid state. Besides, why go through the care and feeding hassles of gigging with a tube amp only to make it sound solid state?

On the other hand, if you’re a purist playing blues, blues-rock, and certain styles of classic rock, the response of a tube amp and pure analog effects pedals will offer the preferred sound. It’s simply a matter of picking your battles. That is to say, if it’s a high-profile gig, then you’ll want your best gear. If it’s a roadside bar where people will be doing their damnedest to talk over you, you may want to go lightweight and solid state.

* Dumble amps were made by H. Alexander Dumble in the late ’70s to ’80s. The preferred amp of guitarists such as Eric Johnson, Robben Ford, Carlos Santana and Larry Carlton, each Dumble was hand-built and voiced to the playing style of its eventual owner, who waited three to five years for their amp. Only 300 made, Dumbles sell on the vintage market for anywhere from $25,000 – $50,000, and as high as $160,000.

Cables pretty much don’t do anything but pass signal. As a result, the materials and properties of those materials are turned into features, and subsequently the subject of marketing-speak and endless screeds of pros and cons. For example, oxygen-free copper (OFC) is supposed to have better conductivity, and therefore “sound” better than standard copper wire. The problem is, that’s kind of hard to prove unequivocally.

According to Roger Russell (former director of acoustic research at the McIntosh Laboratory) who is quoted often in online debates regarding the benefits of oxygen-free copper, better sound through increased conductivity is not a feature of OFC. According to Russell, “Highly refined copper (C10100 Oxygen Free Electronic or OFE) with silver impurities removed and oxygen reduced to 0.0005%, has only one-percent higher conductivity than C10200, known as Oxygen-Free (OF). Its conductivity rating is no better than the more common C11000 grade. However, C10200 has a 0.001% oxygen content, 99.95% purity and minimum 100% IACS* conductivity.” He further states that C10100’s improved conductivity is insignificant in audio applications.

You’ll never take me alive, coppers

Naturally, such a statement causes manufacturers of audiophile cables to foam at the contacts. One opposing argument is that Russell only mentions two types of copper, and there are more types of OFC. Beyond that, there isn’t a specific, universally agreed-upon set of manufacturing specs and processes to make OFC, and nothing quantified for audio applications.

So, when manufacturers tout OFC, are they taking you for a ride? Not really. Keep in mind that Russell was attempting to debunk the notion that OFC speaker wire did nothing to enhance sound quality in home stereo systems other than separate audiophiles from their trust funds. However, his main thrust was conductivity alone. Perhaps there’s more to the story than a simple conductivity rating? Some cable designers say you need to look at the atomic level.

One possible explanation for the perceived improvement of sound with oxygen-free copper cables is the fact that copper is crystalline in nature, with each crystal being a boundary that electrons have to cross. Typical high-purity electrical grade copper has approximately 1500 crystals per foot, which must be crossed by signal being transmitted through the cable. Now, think of the impurities in copper wire like knots in a rope, around which electrons have to navigate. Travelling around these impurities can cause phase shift and distortion that degrades sound quality. OFC is like pulling the knots tighter, which reduces the hurdles electrons must travel through, thus reducing distortion and phase shift. Another take on OFC is that the process of electrolytic refining also removes other impurities, most notably, iron, which can cause resistance. Be advised that the length of cable for these effects to be noticeable is up for grabs—some say over 50 feet—which for the home stereo is not an issue, but if you’re wiring a recording studio, oh yes it is.

Another perceived benefit of oxygen-free copper is due to the susceptibility of copper to corrosion when exposed to air. If you’ve ever had the pleasure of removing an old car battery, you know that copper exposed to oxygen corrodes battery cables, and stops conductivity dead in its tracks (electrons go in, but they don’t come out). According to tests, oxygen-free copper also runs cooler than other conductors. It’s more resistant to shorts, more durable and long-lasting, and is far less likely to corrode, due to the reduced oxygen content—at least, that’s the common wisdom.

Oxymoron no more

In light of all this, it becomes clear that the reason for OFC is due to consistent signal transfer in precision applications, longer life, greater reliability, and better performance over long cable runs. As such, if you’ve just installed a Rupert Neve Designs 5088 console in your studio to the tune of six figures, you’re going to want your cables to carry that tune all the way to number one on the Billboard charts. And, as Mogami states, there is no single magic bullet to creating superior cables. Rather, a combination of several factors, of which their years of research has determined that OFC copper is one. That, and the fact that cable is not meant to modify or alter signal in any way. Its job is to pass audio as transparently as the laws of physics will allow.

Finally, if you’re one of those engineers who likes to tweeze every microgram of sound out of your equipment, oxygen-free cable certainly isn’t going to hurt.

* IACS: International Annealed Copper Standard