Guitar Amp Overdrive for the Studio: The 5 Stages of Tone

Knowing how guitar amps distort and create their tones is half the battle. Whether you’re using a real tube amp or an emulation, these are the principles that factor into good overdrive sounds. Image by Benford Harris.

Guitar amps are peculiar musical devices. Especially tube amps and their emulations. Some guitarists regard amps simply as a means to amplify their tone. But others view their amps as instruments in their own right.

Considering the extent to which guitarists use their amps to create unique, signature tones, guitar amps are arguably the most complex type of amplifier you’ll encounter in the entire world of audio. And understanding them will help you get much better tones both in the studio and on stage. 

Gain Staging

Gain staging is a huge and important topic in audio, and this is especially true when it comes to guitar tones.

What does it mean in this context?  Well, there are several points at which overdrive, (aka “saturation”, “breakup” or “distortion”) can be reached on a guitar amp. Each saturation point has its own specific flavor.

“Headroom” refers to the available clean power of an amp, meaning: how high you can turn up the amp volume before it distorts?

Higher-watt amps generally have more headroom. That’s why guitar players who like pristine clean sounds often gravitate toward higher-wattage amps. Even when they’re performing in louder band environments, they can turn up their amps and still produce a clean tone.

On the other hand, guitarists who like amp overdrive often don’t need—or want—nearly as much headroom.

Let’s take a moment to dissect amp overdrive and learn where that saturated amp sound comes from. 

1. Power Tube Saturation

The holy grail of amp overdrive for me—and for many others—is found in the power tube. Power tube overdrive comes from pushing the full output potential of the amp really hard. Think of turning a simple tube guitar amp that has no master volume on it up to at least 8. 

The kind of  overdrive you get from power tube saturation is full and rich. If you push it enough, you may even hear tube “sag”—a term for a compressed sound you get in response to a drop in voltage.

This kind of distortion requires that you run the amp loud. Or at least, nearly as loud as the amp will go. More on this in a minute. For the studio, smaller tube amps can usually offer a very big sound—and at a manageable volume level.

2. Preamp Tube Saturation

As amps evolved to accommodate guitarists’ preference for more overdrive, master volume knobs started showing up on them. Master volume control allows you to push the preamp tubes to create overdrive without requiring massive amounts of volume. 

Although driving the preamp section indeed does indeed create overdrive, it comes with a very different tone than power tube saturation. Preamp overdrive tends to be more fizzy and bright. This isn’t better or worse. Just different. 

Personally, I prefer non-master volume amps. But that’s just my taste. And even for me, a combination of both preamp and power tube saturation can be divine.

To achieve both preamp and power tube distortion in a more simple tube amp without a master volume control, I might run an especially hot signal into the front end to distort the preamp as well by using a pedal to boost the signal I’m feeding the amp. I’ll then turn it up louder than anyone within a four-mile radius would like. 

3: Speaker Breakup 

Depending on the type and specs, speakers can also overdrive or distort if you play your amp loud enough. 

I’m convinced that this is an important component of Clapton’s Cream-era tone. I liken speaker breakup to more of a “fuzz” tone. I think people mistakenly believe Clapton used fuzz, when really it was the combination of preamp saturation, power tube saturation, and speaker breakup on those Cream records. 

Some players don’t like the sound of speaker breakup. David Gilmore avoids this kind of distortion by using very efficient speakers. He prefers to use a Big Muff-style pedal (like the Vick Audio 73 Ram’s Head paired with a Colorsound Power Boost) to get his gain. 

As a general rule, the lower the power handling or the smaller a magnet a speaker has, the more it will drive. 

A speaker with a bigger magnet will tend to remain cleaner in the low end as it’s pushed. This is very important to know when it comes to choosing speakers.

A speaker with a bigger magnet in a lower-wattage amp will be louder, since the speaker won’t get maxed out and become a bottleneck for level. More on this later. 

The rate of breakup depends on the speaker’s cone density and the relationship between the thickness of its top plate and its voice coil winding height. Breakup actually has nothing to do—at least directly—with power rating. You can read more about it here from my friends at Premier Guitar.

4. Output Transformer

Output transformers are the last audio stage your signal passes through before it hits the amp’s speaker. And last is hardly least here. Output transformers too can saturate when pushed beyond their limits. Some guitarists—including me—adore the gentle compression that happens on a 5E5 circuit. (The Tweed Pro style of amp is a popular example).

This subtle kind of compression is achieved by sending a more powerful signal into the transformer than it can “handle,” or perfectly reproduce. This attenuates the low end, and the transformer just won’t pass the full signal along to the speaker. (Leo Fender used this technique to prevent speakers from blowing up.) This can be a welcome trait however, especially for leads.

If you take two amps that are the same wattage and put two different transformers in them, you will notice a big difference. The amp with the more powerful transformer will seem to have a faster attack and a gritty bite with more low-end push. The amp with the lower-rated transformer, by contrast, will feel a little “softer” and have a nice, gentle compression and less of that woofy low end. 

To recreate this kind of light transformer compression at lower volumes, I use an Effectrode PC-2A tube compressor to emulate transformer saturation and tube sag. (More on sag in a moment.) This comes in handy when I have to use a big amp at a smaller venue and need some nice saturation without maxing the amp out.. 

Mark Baier from Victoria Amplifier wrote a wonderful article on this subject if you’d like to explore it more deeply.

5. Rectifiers 

In technical terms, a rectifier converts the AC current coming into your amp to DC current. There is a lot more one could write about this process, but it’s not super-important for understanding its influence on tone. 

There are two styles of rectifiers—tube and solid state. I like to think of them as computers. Older computers (tube rectifiers) can’t process information as fast as newer ones (solid state). But unlike the case with computers, in guitar amps, older doesn’t mean obsolete. 

As you play an amp louder and louder, more sonic information has to be translated from AC to DC. The faster the rectifier can translate it, the more attack and transient response and the less “sponginess” the amp will have. 

The slower the rectifier makes this translation, the more “squishy” the amp will feel. It will sound like gentle compression. You may also hear “sag” when really pushed hard: when the rectifier is at its limit, it will duck the signal for a brief moment when you hit a note or chord. (This sag effect can also be replicated using the Effectrode PC-2A tube compressor mentioned earlier.)

Tube rectifiers are slower to convert AC to DC than are solid state rectifiers. Tube rectifiers will therefore compress and sag much more than solid state amps— and some tubes will do so more than others. Solid state rectifiers won’t compress much, if at all, and will keep more attack in the signal, even near their limits. 

Again, it’s not a matter of better or worse. Rather, it’s how you want your amp to sound, feel, and respond. I’m a big fan of tube rectifiers. But solid state has its place, and many even prefer it. 

A Rubik’s Cube of Tone

As you can see, there are quite a few points at which amp saturation can happen. 

If you’re using a master volume amp and keeping the master volume on the low side, you’re not just missing out on power tube saturation—you’re also missing transformer saturation, rectifier sag, and speaker breakup. 

So what kinds of saturation do you want? It really depends on what sound you’re inspired by or looking to re-create. 

The Beatles used Vox AC30s with tube rectifiers and no master volume. When you hear crunchy Vox tones on their records, it’s important to know they’re coming from several places in the amp. 

Using an amp with preamp gain and a master volume control along with a solid state rectifier just won’t get you that sound. The speakers aren’t being pushed, and neither are the transformer or rectifier. 

If you’re into more modern sounds with tight overdrive versus loose, vintage overdrive, you’ll want master volume control. You may also not want any sag or transformer saturation. 

Both tones have their place, but if you had to choose just one type, II would argue that it’s easier to recreate the pre-amp saturation tones of master volume amps than it is to recreate non-master volume tones. This is especially so in the studio.

Into the Wild

Although I prefer non-master volume amps, they can be tricky in certain live venues. For example, I love my Victoria 35115 Tweed Pro-style amp on volume 5. It’s a sweet spot for me. I even go so far as to use a Brown Box to ensure the amp is getting the same voltage every night. This way I know volume 5 sounds like volume 5. 

But some venues just can’t take that much volume. So I have to lower it. But then everything changes! All of a sudden, there is less of that gentle rectifier compression, and all of my pedals just sound “off”. It’s kind of like baking cookies and not adding enough sugar. Gain staging the amp is a major part of my tone. 

If I had a master volume amp with a big transformer, a solid state rectifier, and high headroom speakers, I could probably go from volume 5 to volume 3 and keep a much more consistent tone. It’s just not my kind of tone. But it’d be easier. For better or worse, I happen to like the sound of amps when they’re at their limit, gasping for air.

In the controlled environment of the studio however, you have more flexibility for getting an isolated amp right up to its sweet spot. Unless of course “your studio” is also “your apartment”. Then you may also run unto this same trouble.

By now I hope you’re feeling justified about being so tweaky with your amp as well. Guitar players get a bad rap for always trying to find a sweet spot worth their volume. People often think they’re nuts. But guitar amps are just not like other amps. There is a lot of chemistry that goes into a great guitar amp tone. I hope this article shines some light on the many inputs that affect your tone.

Sure, you could use a digital modelling amp that emulates all these components, but where’s the fun and sense of danger in that? If you were to go that route, at least you’ll know go in knowing what makes each of those emulations sound the way they do, and what variables you can adjust to get the kinds of tones you’re looking for. You’ll also know what kind of fun you’re missing out on.

Special thanks to Wayne Jones of Headstrong Amps and Chris Benson from Benson Amps for supplying me with a wealth of amp knowledge and assistance with this article!

Mark Marshall is a producer, songwriter, session musician and instructor based in NYC. He has created a full-length course on guitar tones called  “Producing and Recording Electric Guitar”.

Please note: When you buy products through links on this page, we may earn an affiliate commission.