It’s Tube Time

August 9, 2016

Digitech - Ricochet

Written by PGS Staff

If there’s one thing that the vast majority of us can agree on, it’s the notion that tubes are king. Sure, solid-state amps have their place, but to this day, nothing gets the blood pumping like real tube action. Though we know that we prefer tubes, a much smaller percentage of us knows why. This week, we’ll be looking under the hood of your tube amp, giving an overview of power tubes and how the various vacuum valves affect your tone. 


The Tiny Backstory

The quick history: in the late 19th century, scientists were experimenting with gas-discharge and electrical-discharge tubes. Thomas Edison and Nikola Tesla are among some notable scientists who experimented with tube technology and helped lay the groundwork for the modern vacuum tube. The tube amp as we know it was popularized in the ‘30s and as we all know, guitarists took those things and ran with them, discovering that by pushing the tubes they could get a crazy new tone: overdrive! Rock ‘n’ roll was born. 


The Four Tube Groups

When you do the requisite research, you’ll notice that most of the popular tube amps on the market today use a few common tube types (each associated with a certain tone). The typical tubes in use today are: 

EL84This tube is most associated with the “Vox chime.”  It is used predominantly in Class A tube amps—where the amp runs all hot, all the time. The EL84 has sparkling highs and a crunchy midrange that responds very well to being pushed—just like in an AC30. 

EL34Marshall Stack. That is all. The EL34 is the wall-of-rock sound that we all grew up with—whether you grew up with Plexis or JCM800s, you grew up with EL34s. They are known for their ability to produce distortion at lower power, making them desirable and essential for amps that are chasing that full stack sound. Some players are experimenting with swapping out EL34s for KT77s or 6CA7s, often reporting that the 6CA7s offer a good cross between the EL34 and 6L6 tones. 

6L6The big, clean tone that Fender is known for comes from the 6L6. This tube is what gives the Twin and the Super Reverb their power, allowing rich, full bass and sparkling highs. The tone of this tube is typically considered an “American” voiced tone, frequently used in Fender-styled combos and many more-modern American amps. KT66s are sometimes used as a replacement for the 6L6 with many players considering them to be the smoother overdrive of the two. 

6V6The 6V6 is the old-timer of the group—known for providing that sweet tweed tone to smaller vintage combo amps from the 50s and 60s, such as the Fender Champ and the old Gibson GA-40. 6V6s fell out of favor (to be honest, they fell out of manufacturing) for many years and are currently experiencing a resurgence due being available on the market once again. 


ThorpyFX - Fallout Cloud

Swapping Tubes

Changing your tubes can have a drastic effect on your tone. Even simply changing brands can produce a stunning result in your amp. Unfortunately, the only way to know how a brand will sound in your amp is to: put those tubes in your amp. However, the good news is that most of us guitarists are die-hard tinkerers and you’ll probably have a lot of fun experimenting. You typically should not simply swap power tubes in and out—as most tubes are going to have unique or incompatible circuit/voltage/bias specs. We recommend always taking your amp to a pro, unless you are yourself a pro—manufacturing and quality-control variations across brands mean it’s safer for you and your amp to have a tech swap out the tubes and perform any necessary tweaking/biasing/re-wiring necessary to make the jump. If you’re simply replacing a tube with one of the same variety, we recommend handling the tube with a clean, dry cloth; finger oil residue on the tube can linger and create a hotspot, almost ensuring that tube will blow faster than others  


Your Mileage May Vary

There is a ton of manufacturers creating a ton of different types of tubes that will yield—wait for it—a ton of different tones in your amp. With plenty of resources available online, you can start to hone in on a few choices that might yield you an improvement in your stock tone. You’ll need to actually make the leap and get the tubes installed to know for sure, but when you arrive at that glorious moment when you hit a power chord and the sound you’ve been dreaming of comes right back at you—it’ll all be worth it. 

 One of the best resources online is YOU—if you’ve got anything to share about swapping tubes out, let us know in the comments and let’s discuss. Thanks for reading! 



  1. Ricky Rodriguez says:

    I have a rare Ampeg SR212T…..that’s 2 celestion G-12’s and 4 Groove-Tube tubes. Sounds amazing. I’ve had it since 2010 and the tubes are original. When do I change them, how do I know when to change them and what other alternative tubes would be best in that amp? Ampeg didn’t make guitar amps other than bass amps over the last decade I believe, so the amp is really rare but sounds so nice.

    posted on August 9, 2016 at 8:43 am
  2. Wiley S says:

    I like JJ Tubes but Groove Tubes are nice as well.  If it sounds amazing, it doesn’t need new tubes.  If the tubes go telephonic, you will know you have a problem.  G oogle up some JJ or EuroTubes and when are tubes bad.  Plenty of info there.

    posted on August 9, 2016 at 8:55 am
  3. Jim R Baxter says:

    Tube Amps have one thing that transistor (solid state amps)  really don’t have unless they produce circuits to entice it.
      These are the harmonics and if you don’t know what I mean it’s really simple. The old Juke boxes in restaurants use to let you play music for the whole restaurant to enjoy and it was more than the finished recording had going for it. It was more than that big speaker - it was really the third harmonics created by those early amps and it worked great for time.
    It created a warm run off and carried the essence of the music,all the melody with the vocal inspirations of the singers into a singular expression.
      The effects were an accident that worked. Like the Colaviolin that Gibson distributed in the 50’s (made in France) and sent the song Runaway world wide. These things made music a drug.of its time.

    posted on August 9, 2016 at 9:01 am
  4. tINY says:

    Typical tone report article.  I appreciate generating interest.

    But, these descriptions here are a bit misleading.  For example 6v6 tubes are used in Tweeds and the Blackface deluxe….  The difference in sound is due to the tone circuit and the phase inverter (the pre-amp tubes that drive the output tubes).  The newer amps also used fixed bias instead of cathode biasing…  but those kind of nuances may be beyond your target audience….

    posted on August 9, 2016 at 9:12 am
  5. Larry says:

    Jim Baxter - it’s the clavioline I think you’re referring to.  And yes, it was on Del Shannon’s “Runaway” and also “Telstar” by the Tornados the next year.

    posted on August 9, 2016 at 9:31 am
  6. Thom Opal says:

    Unfortunately, this article reinforces two popular Internet fallacies:

    1. Tonal character resides solely in the power tube choice, rather than the circuit - FALSE

    Power tube character differences are real, but are relatively minor compared to the circuit.  In my experience I’ve found that circuit predominates the amplifier character - thus preamp circuit architecture and voltages, phase-inverter type, power section biasing (cathode- vs. fixed-bias; or single-ended), rectifier type, negative feedback, etc. really determine how the amp responds much much more than the kind of power tube it uses.  So you can get a wonderful Vox AC30 sound with 6V6GT power tubes, for instance, or dial in an incredible tweed-style amp with EL34 power. 

    2. Finger oils cause early power tube failure - FALSE

    This misconception comes from the real risk of finger oils on high-temperature halogen quartz lights.  Power tubes (and miniature preamp tubes) don’t suffer the same risk at all.

    PGS normally has MUCH better quality information and demos, so I’ve come to expect a more professionalism.  Please research prior to recirculating misinformation.  I’m hoping for better in the future - THANKS!

    posted on August 9, 2016 at 9:34 am
  7. 'BluesHarpo' Rafi says:

    I have a vintage tube-amp (1962 ? ) GRETSCH Super Bass 6159, who sounds great. I use it for harmonica. But it’s just too heavy and bulky to carry around for gigs.  What would you recommend in a more handy size and weight for Blues and Rock ?

    Thanks, cheers.


    posted on August 9, 2016 at 9:36 am
  8. Ted Schoenling says:

    What I find odd is that people will run a full blown distortion pedal in front of a clean tube amp.. thus getting all that ‘distorted’ sound from a solid state device… and then deride a ss amp.

    A clean boost in front of a tube amp makes sense… but why be so nasty against SS when you run you RAT or TS in front of an amp thus changing its tone completely

    posted on August 9, 2016 at 9:54 am
  9. zach says:

    Check out some solid state vs tube amp BLIND tests on Youtube, such as intheblues does. Tube aficionados may come away surprised at what modern modeling amps can do when they are not biased (!) by knowing in advance what they are listening to.

    posted on August 9, 2016 at 9:55 am
  10. Michael Gorman says:

    I once went out to buy a Fender Twin from a second-hand music dealer-I found a slightly beaten up one, and 2 of the 6L6 tubes were smashed in it-obviously had seen some rough handling on the pub circuit! Anyway I bargained with the dude saying ‘look man this amp is completely trashed, it is going to take a lot of work to get it working…’ Well I got it for $300, all it needed was a couple of new tubes and it was fabulous!

    posted on August 9, 2016 at 9:58 am
  11. C. Montalvo says:

    I have an old Fender Solidstate amp that I’ve used live for the past 21 years. Over the years I have considered replacing it with a tube amp, but I have yet to find a tube amp, within a decent price range, that sounds anywhere near as nice. The amp starts to breakup around 4…5.

    I guess my input here is that you really need to shop the amp, not the tube.

    posted on August 9, 2016 at 10:08 am
  12. BK Butler says:

    Tubes have been very good to me… ;)
    (My unending thanks thanks to David Gilmour and Eric Johnson…)
    Here is probably the most definitive article ever written about the ‘Tube Sound’ vs.
    Solid State:
    Btw, it’s the 2nd order harmonic that is the most predominant and musical in the tube sound.
    There are many other factors that come into play with tube preamps and tube power amps including overdrive threshold point, impedance loading and damping factors… but discussions of every aspect within the tube sound would take up waaaay more space than we have here…
    Bottom line:  ENJOY the TUBES!
    /BK Butler

    posted on August 9, 2016 at 10:55 am
  13. soulman says:

    Nice try PGS staff but there is a fairly abundant amount of misinformation here some of which Thom Opal points out.  Amp circuits may be designed around a particular type of power tube but the type itself plays far less importance in the character of the amp than the circuit design itself does.

    posted on August 9, 2016 at 11:44 am
  14. Walter Bonczek says:

    I have a peavey tube classic with strat copy….Would replacing the bridge with Seymour Duncan give me more bite?...

    posted on August 9, 2016 at 11:45 am
  15. Walter Bonczek says:

    I have a peavey tube classic with strat copy….Would replacing the bridge with Seymour Duncan give me more bite?...or would I be better off with celstions

    posted on August 9, 2016 at 11:47 am
  16. Juan Antonio Cagigas says:

    I agree with Thom Opal about the “finger oils” hurt tubes bit.  This article was not so hot losing validity on that alone.  No hard feelings I still enjoy reading what you guys print overall.

    posted on August 9, 2016 at 12:17 pm
  17. Bob Wentworth says:

    I’ve played both types of amp and I do prefer the even-harmonics of tubes. I must point out that the greatest sound difference is in the speaker(s) and/or the cabinet.  The speaker and cabinet translate the amplified signal into sound.  Great amp + bad speaker = flat lifeless sound and feel.
    Great speaker + so-so amplifier = pretty good sound and feel. Great speaker + great amp =
    awesome tone and feel.  I’ve played modeling amps that sounded great ,,, through a good speaker and cab.  The room you are playing in determines the type of speaker cab you should use.
    The worst thing for tubes is to come in from the cold and not allow time for the tubes to warm up.
    One must try different amps and instruments to discover what works for you.  The search is your quest !!  Enjoy it.

    posted on August 9, 2016 at 3:03 pm
  18. Rob Fawcett says:

    What a lousy, shallow, uninformative, downright misleading article. There’s more insight and expertise in the comments, and much still unsaid. Not even any mention of preamp tubes, which need no rebiasing and can be swapped out cheaply and with great results.

    The ubiquitous preamp input tube is the ECC83 (12AX7). I like a crisp crunch to my sound, without too much fizz or compression, and find that swapping the preamp V1 for a very similar but lower gain 5751 makes me happier with most amps and absolutely transforms many.

    BTW JJ Tesla offer an odd take on the 6V6, a much larger bottle than is conventional, which I like a lot, and their EL84s are great. I agree with the poster who suggests that tonal differences are much less to do with the power tubes than many assume, but whatever the ultimate factor I do tend to fall in love with EL84 amps remarkably regularly.

    posted on August 9, 2016 at 5:33 pm
  19. Michael Breeman says:

    The article is rather limited in it’s information but hey how many of you in guitar-land really understand electronics let alone valve/tube electronics, so I believe although a bit short on technical information it is useful as general information. Some respondents are on the right track re the nuances of valves/tubes, especially when they mention the compression so apparent in early Vox ac30s, just listen to some early Shadows instrumentals. Also valve/tube amplifiers provide a unique tone which is also partially due to the output transformer and the valve rectifier circuits they employ. Again some current amps offer both valve and SS rectifiers which are readily switchable and provide significant difference in tone when the amp is driven into overload.
    Having said all of that i believe that many guitarists are sucked in by the hype but looking for that unique tone is a worthwhile pursuit.
    Did like the article!

    posted on August 9, 2016 at 6:26 pm
  20. Bob Radke says:

    I am a tone junkie and its not a bad thing. I have been playing guitar since 1962 and I cut my teeth on a tele played through on old amp playing the theme song to Bonanza. For me it all started there. It all goes back to making sure you have a good amp that works well with your playing style, it will make your guitar and you shine like the Sun.

    I believe every man , woman, boy or girl who becomes a guitarist will find there tonal niches by discovering there own amps of choice, for instance.  A 1953 Gretsch artist amp I bought for $10 was what got me into tube amps it had a 10 inch Rola speaker 6v6 tubes and sounds like a tiger with an attitude. Over time I went wild and purchased a tweed fender Champ,a tweed Princeton, a tweed Harvard and a tweed Deluxe, as well a brown fender Princeton and brown Deluxe, and then came the blackfaces a Champ, VibroChamp, Princeton, Princeton reverb, Deluxe reverb and Vibrolux reverb and Pro reverb. Still have them all,  most are running with RCA tubes. remember no one amp can do everything so step out and do some experimenting. The new Fender American Vintage reissue series amps and the Vox ac15 reissue amps are great amps to get rollin on. Then you can start buying a bunch of cool guitars. Keep on playin.


    posted on August 9, 2016 at 6:26 pm
  21. CD Woodbury says:

    “...Sure, solid-state amps have their place, but to this day, nothing gets the blood pumping like real tube action.”

    Believed that for 25 years, these days rocking a Quilter MicroPro head with WGS 4x 10” speaker equipped cab. Have guitarists asking me about my “boutique” amp all the time at my gigs. Solid State has (finally) caught up.

    Currently selling a ‘71 Super Reverb, the last tube amp in my collection.

    posted on August 9, 2016 at 6:26 pm
  22. stratopastor says:

    It IS great to swop tubes (valves) around for different sounds, but there aren’t “a ton” of manufacturers. There are four, I think. There are more than four different-sounding 12AX7s (for example) but they only come from a total of four factories.

    posted on August 9, 2016 at 6:33 pm
  23. Andre Bordeleau says:

    @ tiny…you are right….like in the maybe you should not be here….snob much?

    posted on August 9, 2016 at 9:58 pm
  24. Steve says:

    I have had solid state and tube amps. I know that I definitely prefer tubes. Until recently, with the tonal advances in solid state & modeling amps, I never would have considered solid state again. But there is some fantastic equipment out now. The only problem (in my opinion) is to get a non tube amp that sounds fantastic, you are going to spend as much as you would for a good tube amp. Pro quality equipment always comes with a price… so I’m sticking with my tubes, three knobs, class A, fantastic tone.

    posted on August 9, 2016 at 11:49 pm
  25. Bryan Spacecat says:

      There are certain instances where any amp will do, mostly depending on the guitar you play, whatever effects you use, how much volume you need and whether or not you have to run your signal through the mixer and front speakers. Then there are instances where a tube amp shines like a diamond in a goat’s ass. That leaves you with two choices. Either buy a nice tube amp, or break down and buy both an ultra dependable SS amp AND a sweet tube amp.

      I opted to buy 7 tube amps and 3 SS. I’ve pretty much got it covered.

    Oh yea, the SS amps are; 2 made for acoustic guitar, and 1 ultra small practice type amp. The tube amps range from a tiny 1 watt bug the size of a stomp box, to a 22 watt Deluxe Reverb. I’ve been down the 100 watt and up stage and found that the only time you need that much power is if you are playing outdoors without a sound system. Plus the weight and space limitations have a way of wearing you down. Oh yea, and eventually you get smarter. ;)

    posted on August 10, 2016 at 2:50 am
  26. Dennis Davidson says:

    I think I understand the answer to the question, “Why are tube amps preferred to solid-state amps?” to be “Because tubes produce overdrive.” The question could be reframed a bit more meaningfully, that is in the context of the period. Guitar players at the time that Rock and Roll was conceived used what was available to them, which was tube driven audio. If solid-state technology had been around, they would have used that, and overdrive may never have been a thing. Therefore, rock and roll may not have endured or even survived after a few years without tube driven guitar amps, and that’s what makes them “better.” Sure, you may have an opinion as to which technology you prefer for an amp, but the heart of the rock and roll sound lies with tube driven amps.

    posted on August 10, 2016 at 12:28 pm
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  28. james beavers says:

    A few random observations, not even gonna try to write “well”, but anyway..Tubes Rule. Tube amps remain best. Their sound is sublime, with a depth and shimmeriness nothing else can match. Now with that said, I must admit that SS and digital amps have come a long way. It’s surprising how good my Fender Frontman 2x12 sounds, and that’s with the generic speakers. I’ve listened back to the 2, 3-minute noise segments, er-um-uhh, I mean “songs”, me & friends have done, and I once had to think hard to remember what amp I used on one. It was the Frontman. I was thinking it may have been my AC30, no joke. And I ordered a Marshall Code 25 just to be an irresponsible retard, and the sounds within are WONDERFUL. Involuntary “Wow"s were happening between me and a friend. 
      My Bugera 1990 and my Marshall DSL15 both use “American” tubes, and yet their sound is VERY “British”.
    Thx for putting up with me, All. ;)

    posted on August 12, 2016 at 2:04 am
  29. dave jones says:

    Umm , Andy ?

    You never did really answer the question did you ?
    Why most people like tubes ,,
    just saying

    posted on August 13, 2016 at 12:38 pm
  30. Greg Coats says:

    I agree that you should just shop around for what sounds the best to your ears I’ve had Fender Blues Jr’s that sound great as a pedal platform and I had a solid state Vox that I didn’t realize had a unique sound until years later when I tried to replace it. I kick myself for selling it.

    posted on August 15, 2016 at 8:44 am

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