Best Guitar Amplifier Tubes in 2020

JJ 12AX7 / ECC83 Preamp Vacuum Tubes (Three Pack) Review:

I just received these tubes in the mail yesterday, and I installed them right away in the preamp section of my Jet City 20w combo amp (JCA2112). The tubes in the amp previously were marked "made in china" and were 12ax7R, which I think must be the same as the ax7s, do to their pretty high gain tendency. I picked the JJ's at the recommendation of the Jet City's product support guy, and based on some positive feedback from fellow musicians.

I've only had the tubes in for about 36 hours now, but last night I put them through about 3 hours of gig time and they sounded great. The item description that Amazon provides is really pretty right on- these tubes increase clean headroom nicely. The original stock chinese tubes broke up almost instantly, and while that was fun for heavier rock, I've always been displeased with the lack of clean tones my amp could provide. The JJs changed all that in a hugely noticeable way. I'm reserving my final judgement for a few weeks from now when they've had another 10 hours of playing time, but here's what I've noticed so far:
-Great headroom and very musical, lush breakup- not harsh, jagged distortion, but creamy, bluesy drive.
-tight lows, very pronounced mids, and a nice, chimey high-end that isn't brittle at all.
-The note separation that the increased headroom gives is really great, and even with the preamp gain cranked, lead runs and hammer-on pull-of stuff has a nice, clear quality to it that allows notes to cut through the breakup in a really cool, vintage sounding way.

I guess I should also add that while this 3-pack isn't eligible for Prime, I received the package in 3 days and it was very well-protected. I would recommend the JJs, especially if you have an amp that comes stock with chinese tubes. These really do make a difference in tone.

Electro-Harmonix 12AU7 EH Vacuum Tube Review:

I got this for my Bravo Audio Ocean amp to compare with the stock tube. I burned in the stock tube for around 40 hours, and got a decent feel for it. At this point, I put around 120~ hours into this EH tube. The quality is nice overall. In comparison with the stock tube, the lows are much less pronounced (which is good, as they were almost overbearing with the stock tube) and the lower-mids to mids clarity seems much improved. The highs are most certainly there. Overall clarity (such as instrument separation in the mix) seems slightly better than with the stock tube, but this is difficult to say as I have not burned in the stock tube as much as this. Both tubes had no noise problems for me personally, but it seems like you either have a noise problem or you don't, attributed to whether the tube is defective or not.

In general, this is a very well rounded tube from what I know and what I have observed (not harsh or overbearing in any particular frequency range). However, the difference compared to the stock tube is not as life altering as some people would make it out to be. However, that said, any differences between the tubes may be more noticeable in some genres of music I do not listen to. Genres I tested through this tube include: jazz, progressive metal, classical, and acoustic pieces. This tube seems like a good choice for most genres because of its seemingly well-rounded nature.

For the price, it's worth the purchase even if just to have another tube to switch in and out based upon preference.

Mullard 12AX7 Preamp Vacuum Tube, Single Review:

I'm running 2 Heathkit model A-9B mono blocks as a stereo set. After careful research, I choose these Mullard preamp to replace the worn vintage RCA 12ax7 and 12AU7 tubes I had in these amplifiers. At the same time, I replaced Sovtek 6L6GC output tubes with the current production Tung-Sol 7581A tubes. I'm blown away. Despite these amplifiers being rated at 20 watts RMS, they are driving a pair of Boston A-360 speakers to fill my room with delightfully clear and brilliant sounding music. The bass response is powerful and clear, detailing all of the aspects of the notes whether from Steely Dan's punchy clean style, Chicago's flowing melodic style, or Yes with that distinct Rickenbacher/rotosound combination. For mids and highs, the horn section from Chicago is absolutely stunning through these tubes and the great guitarists playing psychedelic riffs with wa-wa pedals and electrifying leads have a clear and very sweet presence in the sound stage. The quality is both pleasing and exciting to listen to without a shred of harshness and without a single piercing note (you know, that occasional high note that feels like an ice pick to your set drum.) This pair of Heathkit amplifiers just went from sounding pretty darn good to sounding awesome in ways that very very few amplifiers could never touch. If you've ever heard a Marantz or McIntosh with tubes, we are in that arena of fidelity.

I choose these Tung Sol 7581A power tubes for this application because of reviewers who criticized them for being too clean in a guitar amplifier. Given this excellent performance in my High Fidelity system, I would agree; these tubes contribute no discernable distortion which would make them undesirable in a most guitar amplifiers, but it makes them AWESOME in a home stereo!

My choice of the Mullards for the 12AX7 and the 12AU7 tubes was based on similar research where the Mullards were being criticized as too clean for guitar amp service but praising the small Tung-Sol tubes for a sweet guitar amp tone.

These Heathkit A-9B amplifiers were speced out for less than 0.1%total harmonic distortion at the rated 20 watt RMS output with less than 1% Intermodulation distortion and a flat response curve from 6 Hz to 50 kHz and a -70dB signal to noise ratio. With these tubes, I have no doubt these amplifiers are acting as good as or better that their impressive specs. 20 watts rms never sounded so powerful or moving!

If you are considering a high fidelity retube, I very highly recommend this combination.

JJ Electronics Amplifier Tube (T-6L6GC-JJ-MP) Review:

Remember kids:
When replacing your Power Output Tubes (such as these) it may be best to have your amp biased/checked for proper plate voltage settings by a qualified service technician!

If the settings are too hot, it may sound great but the life of your tubes will be much shorter.
Too low and your sound may be brittle or sterile lacking the balls and oomph you like so well.

I have 9 Fender Pro Tube amps and have played full time for over 27 years.

When choosing between 6L6's and EL34's I tend to go for the 6L6's sound that has a more "American" sounding bottom end, not quite as "woody" as the English overdriven tube sound. The bottom end sounds clearer and more distinct with 6L6's, but there is also a lot to be said about the EL34's, too!

Similar to Dell, Gateway, HP, Compaq, etc. not making computers, JJ's does not manufacture tubes, but rather they test and rate them , eventually pairing like kinds within similar tolerances and voltages. This is critical if you have an amp that uses two of these. This will ensure that both sides of the amp output stage are as equal and balanced as possible before any biasing or adjustments.

The "burnt silver/black" inside the tube is called the "getter" which is a chemical that is burnt upon first initial firing and burns up any leftover oxygen or air inside the vacuum tube.

Very nice price - lower than most other places online!

Hope this helps!

Matched Pair (2x) Genalex Gold Lion 12AX7 tube (ECC83) Review:

Really glad I took the plunge on these. I'd rolled through a handful of other 12AX7s in the phono stage of my old Harman Kardon A-300 amplifier -- JJ, Tung Sol, EHX -- and settled on the Tung Sol. And everything sounded PRETTY DARN GOOD. But I kept feeling like something was missing. I couldn't stop tweaking the tone controls and repositioning the speakers ('90s Klipsch Forte II's). Everything sounded fine, better than average, even. But I couldn't help feeling a tiny bit disappointed. It just wasn't quite right yet.

So I dropped a little more cash than I normally would on a matched pair of these Gold Lions and BOOM. There it is. These tubes haven't even had a chance to burn in yet and they already sound like a million bucks. No complaints at all. They recovered my missing lows (the bass control is finally set to flat, no boost), sit my mids right where they belong (very natural, neither too brown nor too boxy) and the highs are clean, warm and distinct with no harshness whatsoever. Soundstage is wider and more engaging, even at background listening volume.

I did a lot of research and read a lot of reviews and opinions before placing my order. A number of easy-to-find reviews online essentially painted the Gold Lions as snake oil, rebranded EHX for three times the price. NOPE! I love EHX. I prefer their tubes in my guitar amplifiers over several other more expensive alternatives. But the I've A/B-ed EHX and Gold Lion back to back in the same amplifier and the new Gold Lion beats a lightly broken-in EHX in this application hands down without even having had a chance to open up a little bit yet. No contest.

I am very impressed. Definitely worth the money and I pray they maintain this level of quality until the next time I need a new set of preamp tubes.

Behringer Tube Ultragain MIC100 Audiophile Vacuum Tube Preamplifier with Limiter Review:

This little gem filled its intended purpose perfectly. I play harp (harmonica) at local open mic/jam sessions with friends. Mostly it's classic rock, southern rock, blues and some country. I used to play through the "house" PA, but found that to be restrictive in some ways, so I bought a small, 20W instrument amp to have a little more control over my sound. Well the little amp has difficulty keeping up with the more powerful guitar amps without driving it too hard (leading to distortion/muffled sound quality).. I didn't want to go with a bigger, more powerful amp, because I don't want to have to lug around big, heavy equipment, so I thought I'd try this pre-amp to keep from pushing the main amp too hard.

I haven't tried it "live" as yet, but I did test it at home. Without the pre-amp, I had the main amp volume set to 8-9, and the three EQ setting equally high. The poor 8" speaker was definitely not happy. Once I plugged this pre-amp in between the mic and the amp, all that changed. With the pre-amp gain control set to almost the minimum setting, and the "output" (volume level) set to the 9 o'clock position, I get more sound out of the main amp with it's settings at 5 than I did with just the main amp set to 8-9, and the sound is SO much cleaner. I am dying to experiment with the gain setting to see what kind control over the overdrive I can get.

The fact that this unit will take either XLR (balanced) or 1/4" TS (unbalanced), or a combination of the two, is a real bonus. The other controls are all very useful, especially the 20dB mute and the 48V phantom power. Not features expected from a device at this price point. The old school knobs allow instant tactile feedback in a dark venue, and the unit puts out very low noise unless the gain is turned way up. One other cool feature - the LED signal level meter doubles as a tube-warmup countdown timer...the LED's progressively extinguish (R to L) until they're all off. At that point, the tube is presumably warmed up. Nice feature, given the absence of an on/off switch.

I did open up the unit to see how easy/difficult tube changes would be, and was impressed by the build quality and design. I'm an electronics tech by profession, so I'm very critical of those things, and this unit is made well, period. I didn't notice any tendency for the power plug to come loose. There is a cheap plastic clip adjacent to the port, to retain the power cord, but it is virtually useless - the ONLY criticism I can make of the entire unit. As a bonus, it is compact enough to fit into my small canvas bag, along with mics, cables, and my harp case.

I look forward to many enjoyable sessions with this little device.

UPDATE: Several sessions later, I continue to enjoy this unit. I can get a very nice "Chicago Blues" sound by driving the gain up and controlling any feedback with the level control. In conjunction with my small amp, I can more than keep up with the loud guitar amps and drums. A keeper.

Mullard Reissue EL34 Power Vacuum Tube; Matched Quad Review:

I ordered a matched quad of these for an ST-70 Custom amp. This amplifier, based on the dynaco ST-70, of course, only has two parts from an original dynaco. Those two are the OutPut Transformers (OPTs) - all other parts are new, including chassis and beefier power transformer and higher value PS capacitors. It's 6EJ7 input tubes are connected triode rather than pentode. Each EL34 output tube is biased individually. All connections on back panel. It drives a pair of Klipschorns which were recently recapped by me. Main sources are CD and streaming 320.

The amp came with JJ's EL34s which had problems. With my ears 3-4 inches from the speakers, I could hear noise which I attributed to the extremely high sensitivity (usually called efficiency) of the cornerhorns.

Then I replaced the JJs (with unknown history, but all four guidepins were broken off) with these Soviet Mullard reissues. Wow! I now have black backgrounds - no noise, not even with my ear against the grill cloth. Mids much more resolved - the JJs sound recessed in comparison, giving them a darker sound. Highs crisp and clean. Now this is more, especially the mids and the lack of noise.

Remember that this is a suspect set of JJs, so not a fair comparison. I will be sticking with these reissues myself - they seem to deserve the Mullard name. I'm ordering another quad.

JJ Electronics Amplifier Tube (T-EL84-JJ-MP) Review:

When my long lasting Russian-made Electro-Harmonix EL84EH tubes, that came with the Cayin HA-1 headphone amp, finally gave up, I was looking for replacements pretty rigorously. If I had the option, I would have most likely settled with KT77 amps (specially the Gold Lion ones), but unfortunately, my Cayin HA-1 only supports EL84s. So, after lot of research, I settled with JJ Electronics EL84s for few reasons. Here are the pros and cons that I discovered:

+ Excellent high quality product
+ Came as 'Matched' set that were already tested and passed quality. Had unique IDs on the box
+ One of the best values for money in current market
+ Said to have last longer
+ Break-in period is not as 'long' as other tubes
+ Breath-taking, fuller low-end definitions when used with good, capable headphones. Immediately noticable
+ Mid-range (voice) is (almost) equally good compared to other tubes I have

- Treble seems to be little recessed. Not sure if they are tubes' characteristics. But hopefully it will open up after some break-in period
- It doesn't specify the warranty period anywhere. But with Amazon, the return window seems to be 60 days
- I still prefer Gold Lion KT77 lush mid-range, but it's entirely my personal preference

Other considerations:
~ Genalex Gold Lion EL84. I have their KT77 for my another tube amp, and absolutely love them for musicality. Can be expensive
~ Mullard EL84. Another affordable alternatives. I have personally never used it, but I heard nothing but good things. Just a tad more expensive than the JJs.
~ Amperex Bugle Boy EL84. Heard good things from other reviewers. But they are very expensive and I didn't want to spend that much money for now

My headphone audio gears are as follows:

For Home :
1) Geek Pulse DAC
2) Cayin HA-1 Headphone Amp (now with JJ EL84 vacuum tubes)
3) Sennheiser HD-650, HiFiMan HE-400S, AKG Q-701
4) AudioQuest Evergreen RCA cable, Pangea Audio Premier SE USB Cable
5) FLAC, ALAC, WAV and DSD lossless music files
6) J River Media Center software

For Traveling/Workout:
1) AudioQuest Dragonfly Black and Geek Out DAC
2) Final Audio Design E3000, 1More Triple Driver, and Apple Airpods
3) iPhone 6
4) MP3 and AAC lossy music files

Final thoughts:
Wish I also had the Mullard's EL84s on hand so I could compare them side by side. As I said earlier, since I still have almost 60-days to try these JJ tubes out, I am willing to take my chances and time to test them fully. Although initially little displeased with their high frequency responses out of the box, I'm impressed with their overall performance thus far. But I do hope that they will open up over time. Because, for the price, they just can't be beat.

Eurotubes Bias Probe for Octal Base Power Tubes. Review:

And top quality parts and tools.

Eddie has been helping me suss out some issues that I am sure are pedestrian to someone of his vast knowledge and experience in all this, but he's been super cool and patient. In the end, although I have purchased tubes and parts from several outfits over the years, Eurotubes get all my business from now on. I would highly suggest you do the same.

A bit of a story here. I have a good friend who for many years custom built some of the best tube amps in the US. He retired from it some yrs back and we lost touch. While attempting to reconnect with him since my amp appeared to be having some minor issues I purchased this Bias Probe from ET to begin testing things myself. Part of my issue was that some of my tubes were new/old stock when the amp was built some 12 yrs ago and some were now unmarked. Long story, short, I lined out the amps "sound" issues with Eddie at Eurotubes and sent him pics of the inside of the amp.
While he was researching the issues and considering which tubes I should change to, to achieve more clean headroom, I finally heard back from my old friend Dr. J. Did I mention he worked as an electrical engineer dept head at Los Alamos lab? Yeah, this guy knows more about high-end electronics than most people alive which is why his amps rocked. Additionally, since he had special parts access all those yrs, his amps were built with all Mil-Spec parts which are far superior to anything commercially available in any era. Dr. J lined out a new set of tube types that would get me where I wanted to be, most of the tubes were not exactly what I would have expected. And they were NOT the tube sets that other tube company's advised me to get. My point? When Eddie of Eurotubes got back to me a day or so after that, he advised me to try using the IDENTICAL set of tubes and in the EXACT same locations as my friend Dr. J advised. Now, what does that tell you about Eddie and Eurotubes? It is not often we find "experts" in any field who are actually "experts" outside of their own imaginations. Eddie is one such person and Eurotubes is obviously that as well.