Tube-based audio gear has been, and still is, some of the most sought after equipment. But, how exactly can we benefit from having it?
What Makes the "Tube Sound"
In order to understand how tubes can help us, we need to understand what tubes do. We also need to understand what they do not do!
Tubes are used primarily for electrical amplification. Whether it is a preamp, a poweramp, or a gain control in a compressor, tubes can been used in just about any form of audio amplification. However, a piece of gear including a tube does not necessarily mean it will have "that tube sound." Why? Because the circuit design itself can have a huge impact on the overall sound.
Some tube circuits are designed to be world-class, extremely clean processors. On the other hand, others seek to exploit every possible coloration a tube can offer us. For better or for worse, the later scenario is the kind of tube gear most audio engineers think of. But what is that sound exactly?
What is "The Tube" Sound?
The tube sound is often characterized as being "natural, warm, fuzzy". Unfortunately this does not tell us what the tubes are doing to our signal!
Since tubes deal with amplification and gain control, common side effects of using tubes is compression and wave shaping. While some people might think tubes sound natural and compression doesn't, the truth of the matter is tubes can compress! Thankfully tube compression and wave shaping can be highly non-linear making it more subtle and generally less objectionable. Your triple rectifier guitar amp is really a heck of a compression machine!
Other common side effects of tubes are the added noise and the type of distortion they produce. Just as with the compression, tube distortion is very non-linear, and normally produces even ordered harmonic distortion. This type of distortion is highly sought after in guitars and when not overdone. The noise (more affectionately called saturation) is able to subtly enhance our signal... or just make it muddy.
Using Tubes to Our Advantage
In order to effectively use a tube, you need to determine why you want to use it in the first place. Are you trying to beef up a thin sounding source? Does a sound cut too much and needs to be smoothed over? Perhaps your signal needs some subtle harmonic enhancement to stand out? These are all options for tube gear! So picking the right approach is key to making tubes work for you and not just muddy up your mix.
One of the most common uses of tube gear to smooth over harsh sounding signals. The most common place you will find these sort of tube designs is in compressors. There is a reason a lot of the most famous vocal compressors are tube!
Another tip is to use a tube microphone from the start. Many (not all) tube microphones have a smoother top end which can be excellent for taming very breathy instruments, vocals, extra bright cymbals, etc.
- Overly bright sources should start with a clean tube mic if possible. Avoid cheap tube mics that will just make things sound boomy and distorted.
- Harsh vocals and more singing instruments like flutes and saxophones can be tamed with a low threshold low ratio compressor that gently rides the signal. Careful not to kill the dynamics too much though!
- Cymbals can be tamed using quicker tube compression if you are looking for the Foo Fighters or similar sound. If you want a less compressed smoothing, use a tube EQ instead (see below).
Sometimes a source needs just little bit of extra sparkle to pop out of a dense mix. In these situations the little bit of harmonic distortion a well designed tube EQ. These sorts of EQs tend to have just a little extra localized distortion in the band you choose to bump up, and can sound very pleasing to the ear. Harmonic enhancers are also a easy way to get that tube sound if you do not want to bump or cut any more frequencies with an EQ.
- With tube EQs, be careful that you do not overkill on any boost. Remember you probably are already sweetening the source by using tube gear to begin with!
- If you opt to use a sonic exciter, remember to dial in the sound very gently. These tools are normally used to add content that was never there. However, with subtle usage you can make a source sparkle.
- If you happen to have a very dirty tubey sounding piece of gear, just run your signal through it with no effect! Sometimes simply running your signal through a compressor or EQ without actually "using" the compressor or EQ is enough to give a little extra enhancement.
Basic Tube Care
If you have never used a tube piece of gear before you need to remember one key trick. Tubes need time to warm up! While every guitar player out there probably knows this rule, it never hurts to remind.
Tubes take time to become stable and in the process they get warmer. Usually a lot warmer! During this warm up time the tube is fluctuating and can produce irregular outputs. At first it will probably sound thinner than you might expect. Overtime it will begin to develop that tube sound but if you started recording while it was cool and finished as it warmed up, boy oh boy will it sound different!
- Generally speaking most pieces of tube gear need 15 minutes or so to be fully warmed up and stable
- Some special pieces of tube gear allow you to control the actual tone of the tube by forcefully inducing different parts of this warm up phase. The Chameleon Labs TS-1 MKII is an excellent example.
- If you going to not be using the tube gear for a good while, turn it off! Tubes can wear down after enough time has passed and the sound will slowly but surely change.
Tubes are an excellent way to add an extra something to your sound that you may have been missing. This does not make them a be-all-end-all of studio processing, but they are good options to have.
It only takes subtle adjustments to go from solid-state to tube as far as technique is concerned. So if you can work a compressor or EQ, a tube version should be no problem. Just take good care of them, and they should take good care of your mixes. Thanks for reading!