The functional difference between the 6L6 and the 6V6 is that the 6L6 is a much higher power tube (about 25w), which means in practice it has a punchier tone with tighter bass and glassy highs. The 10w 6V6 on the other hand is more mellow with a creamier midrange-rich tone, sounding closer to an E34 – all tube tone with less volume, similar to an EL34.
In this article, we’re going to look more in-depth at both tubes and their uses in guitar amps, and hopefully help you decide which one to choose for your own situation.
What is the difference between 6L6 and 6V6 tubes?
The 6v6 is only designed for a max signal power of 5 watts output while the 6L6 can handle 10.8watts of maximum power output. Sonically, the 6V6 sounds warm but gritty – it does a gnarly overdrive without any strident highs. The 6L6 on the other hand is the all-tube sound that is smooth – think melted chocolate.
6L6s generate more power than 6V6s so an amp with 2 x 6L6 tubes can be cranked up louder and will stay clean much longer than an amp with 2 x 6V6 tubes. If you want more headroom use the 6L6 (higher wattage tubes), if you want to break up at a lower volume, use the 6V6.
The 6L6 yields a more focused low-end and the highs have a more pleasant chime. On the other hand, 6V6 tubes have less low end and more mids. They sound compressed when the volume is cranked up (and if you’re going to do that at home, think of the neighbors and get some curtains made for sound absorption).
To most people, the 6V6 sounds more musical for blues. That being said, the amp design also plays a big role in the final sound so these categorizations only serve as general guidelines. They both are great and your choice should be based on your application i.e. playing style and genre.
Can I use a 6L6 instead of a 6v6?
The general answer is no, for the most part, 6L6 and 6v6 tubes are not interchangeable as they don’t bias close enough. Amps are calibrated to use specific valves (6v6, 6L6, EL84, etc.) and are not always well suited to multiple valve usage without circuit modifications. I would strongly advise against it unless you understand the amp design and are comfortable with the technicalities of swapping power tubes.
They need to be rebiased, which is not a simple task. It is much better to let an amp technician handle this situation because it involves advanced soldering. The three key reasons are output impedance, filament current and plate current.
First off, the 6v6s need a higher load than 6L6s for optimum power. You can compare this to the difference between a 4ohm and 8 ohm speaker. Secondly, you don’t want to risk any permanent damage to the transformer or other auxiliary components by trying modifications if you aren’t sure what you are doing.
In simple words, it can be said that one 6L6 tube requires the same electrical space as 2 6V6 tubes. This means that substituting 6L6s into an amp that is powered by 6V6 tubes will need twice the juice from the power transformer.
If your amp lacks a beefed up power supply to house the 6L6, it will end up damaging the amp. The 6L6 heater is rated at 6.3 volts, 900 ma, two times the existing draw of the 6V6. So in amps like Fender Princeton that run on 6V6, replacing the tube with 6L6s will almost always lead to overheating the power transformer and burnout issues.
Similarly, doing it the other way around – swapping 6L6 tubes with 6V6 tubes – can lead to fast burnout. The circuit is optimized for higher power and will eat through the 6V6 very fast if internal tweaks aren’t made to ensure that there are no bias voltages.
The best way to tell if your amp allows any interchangeability is to check the website or the User Manual. If the manufacturer hasn’t categorically stated that you can swap the tubes, it is best to never try this.
Famous Amps with 6V6 Tubes:
The Egnater Rebel 20, Fender Super Champ X2 and Tone King Imperial MKII 20w Head are names you’ve probably heard before. The best known example of a powerful 6v6 combo amp would be the all-tube Fender ’57 Deluxe – a sophisticated unit with a versatile tone that can produce fat and crunch as well as it can do sparkling highs and harmonically rich clean tones. They are also present in the Fender ’64 Custom Deluxe Reverb 20watt Tube Combo Amp.
Famous Amps with 6L6 Tubes:
Marshall, Mesa and Fender amps were all famous examples with the Fender Hot Rod Deluxe, and Fender ’73 Twin Reverb being the most popular. They have also been used in Greer, Carol Ann, Plush and some other boutique and off-the-beaten path amps like the Port City Pearl Amp.
What are 6v6 tubes? A Brief Overview
The 6V6 is a beam tetrode tube that goes all the way back to 1936 – launched as the 6V6G by Ken-Rad and Raytheon. The company was looking for a viable low-powered alternative to 6L6 that required less heater power. Raytheon came up with the 6V6 as a scaled down version of 6L6, which would be ideal for home use.
This made way for 6v6 amps and combo amplifiers – low-wattage amps that have slack low-end but syrupy highs. These amps produce good overdriven tones and they break up very easily at high volume. A single tube can produce 5watts of continuous power and a push pull pair can produce 14 W of power.
Today, they are synonymous with the prevailing ‘All American Tube Sound’ with unflinching and rock-solid tones that have focused lows and prominent highs. They can generate roughly twice the power produced by EL-84 tubes. These vacuum tubes are sold as matched pairs. Here are some good recommendations for 6V6 tubes:
- Genalex Gold Lion 6V6GT Matched Pair
- Electro-Harmonix 6V6GT Matched Pair
- JJ Electronics Amplifier Tube 6V6 S Matched Pair
What are 6L6 Tubes? A Brief Overview
The 6L6 tubes were also launched in 1936 but are very different in design and function. They have a plate voltage of 500v, a 55 watts power outlet and max resistance of 5.6-kilo ohms. After eight decades, their design is largely unchanged and they are still the most widely used power output tube. These tubes redefined guitar amplification and Fender was the first to jump onto the bandwagon in the 1940s.
Most of the good vacuum tubes are designed and manufactured in Russia by brands like Sovtek, Genelex, and TungSol. However, JJ Electronics (Slovakia) and Tube Amp Doctor (Germany) are also famous for making top shelf tubes. Here are KGR’s top three picks for 6L6 tubes:
- Tungsol Reissue 6V6GT Matched Pair
- JJ Electronics Amplifier Tube Pair (T-6L6GC-JJ-MP)
- Tube Amp Doctor – Premium Matched 6L6GC STR Pair
There are some additional variations to consider as well. For instance – the Tungsol Reissue is available in soft, medium and hard classifications. These classifications signify the headroom level and the hard setting has the most headroom. Different tubes are famous for different tones – so do some research before you commit to a purchase.
Final Thoughts on 6L6 vs 6V6 Tubes
Especially if you’re new to tube amps, learning the differences between different types of tubes can seem overwhelming, but by taking a little time to understand how they work in the greater context of your amp, you’ll be better able to squeeze the maximum possible performance from your rig.
In summary, the 6L6 is the higher-powered tube of the two, and delivers smooth, warm tones. On the other hand, the 6V6, has a lower power rating, and this results in a more aggressive, almost snarling tone.