EL34 / 6CA7 / KT77 Tube Reviews

(View our complete selection of EL34 / 6CA7 / KT77 vacuum tubes)

Review Notes
Tube reviews written by John Templeton.

It’s not easy evaluating something as subjective as sound. We each have our own personal taste in music and the way it sounds. I have attempted to add some objectivity by defining some aspects of tube performance that affect any listener, regardless of application, budget or musical taste. The EL34 is a very popular tube and is used in equipment that creates as well as reproduces music. This testing was done using tube guitar amplifiers. With this in mind, consideration has been given to construction quality and mechanical noise. These factors are important to musicians but may not be an issue when a tube is used in the home or studio.

Test Amps:

1973 Marshall Super Lead model 1959 This amp is completely stock using NOS pre-amp tubes. The sound was reproduced through a 1971 Marshal cabinet with 4 Celestion G12M "greenback" speakers.

1970 Marshall Bluesbreaker 2x12 combo

Class A Combo Designed and built by Bernard Raunig. This is a true single ended class A amplifier, using a 5Y3 rectifier and a single 5691 pre-amp tube. With a volume and single tone control this amp really lets you hear the tonal differences between the tubes.

EL34 comparison at a glanceRated 0 - 5 where 0 is Poor and 5 is Excellent

Manufacturer	Model	Microphonics	Mechanical Noise	Detail	Harmonics
Siemens / RFT	EL34	5	5	4	5
Electro Harmonix	EL34EH	4	4	5	4
Electro Harmonix	6CA7-EH	5	5	4	4
Gold Lion	KT77	5	5	5	4
JJ Electronic	E34L	4	4	3	4
JJ Electronic	KT77	4	4	5	5
JJ Electronic	6CA7	5	5	4	4
Shuguang	EL34-B	4	5	4	5
Sovtek	EL34WXT	4	4	4	4
Winged "C"/S.E.D.	EL34	4	4	5	5
Tung-Sol	EL34-B	5	5	5	5
Svetlana	EL34	4	5	5	5

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EL34 Reviews 

Electro Harmonix 6CA7-EH - At last something to replace the hole left since the EI 6CA7 went out of stock. These tubes sound every bit as good as the old EI tubes and are probably my favorite tubes for Hiwatt guitar amplifiers. It’s like they were made for each other. These tubes are like EL34’s on steroids. They handle high voltage and current without problems. As mentioned, there is nothing like a Hiwatt head powered by 6CA7 tubes and driving a 4x12 cab loaded with Fane speakers. This is classic rock tone at its finest. It’s the sound of Pete Townsend and The Who. The 6CA7 has more headroom than an EL34 and by the time you get it really crunchy sounding your pants are flapping in the breeze. Just the right amount of compression for great thick rock tone. Biasing levels can be dialed in from warm to hot without causing significant tonal changes. The EH is well constructed and should not pose any noise problems. If using these tubes in more reasonable systems the EH 6CA7 is capable of some really nice clean tones thanks to that extra headroom. If you want early Van Halen, these are not the tubes for you. If you want something loud and proud, you want to put the EH 6CA7 in your amp.
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Gold Lion KT77 - This tube was a treat to listen to. Since many of us have never actually listened to a KT77 from the original producer, I can not say that they nailed the reproduction. You really have to think of this tube as its own entity. Here is what I can tell you about it. The Gold Lion KT77 is a drop in replacement for an EL34 or 6CA7. The sound however is not typical of an EL34 or 6CA7. It is more of a hybrid. The tube delivers all the mid punch you would expect in an EL34 but also has a top end that is more open and bright. It’s definitely got a bit of a 6L6 designed into it. I tested it in a Marshall 2205 50w head and was able to get that '70’s rock sound but with some bias adjustment could also dial in a VOX-like chime. This really has to be looked at as a new choice in power tubes. If you have a Marshall and never could decide if 6550 or EL34 was the way to go, you now have a third option.
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JJ 6CA7 - Prior to this tube being introduced the choice in a 6CA7 tube was NOS or the Electro Harmonics 6CA7EH. JJ has provided another choice and another price point. JJ tubes tend to be well made and this model fits well into the family. Nice construction, good glass, and the base and pins are well assembled. Although this is a replacement for the EL34 tube, the 6CA7 tube looks nothing like a pentode. In fact, an examination reveals what look like the beam forming plates you usually see on a 6L6 power tetrode. I’m not 100% sure of what’s going on in there. The JJ 6CA7 tube looks and sounds like a 6L6 but biases like an EL34. When installed in a 50W Hiwatt head these tubes just roar. It’s a classic sound for beefy rock anthems. The sound is firm and articulate. A number of customers have reported that this 6CA7 tube is darker sounding. Your mileage may vary but I found nothing dark about them at all. Smooth yes, dark, not so much in my testing.
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JJ E34L / EL34 - JJ is the new name for the Teslovak (Tesla) tube company. A good general purpose EL34. As previously mentioned, the sound is well balanced with tight bass response and great mids.
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JJ KT77 - The KT77 has been gone for many years and original NOS pieces are rare and expensive. JJ electronics has revived the design and released their own version. To my ears it sounds a lot like a 6L6 but has the heater current, max plate voltage and output rating of an EL34. The JJ KT77 has published specs that are identical to the original Genalex specs. The base has pin 1 included but there is no connection to any internal element. The sound is somewhere between an EL34 and a 6L6. Overall a nice balance of tone in bass, midrange and treble. The breakup is earlier than a 6L6 with more compression but not as compressed as the EL34. Unlike an EL34 this tube can be used in place of a 6L6 in Fender amps with minimal modifications. Vintage Fender amps usually use pins 1 and 6 as tie-off points for input grids and screen grids, mounting resistors on the socket. A standard EL34 can’t be plugged in because the input grid would be shorted to the suppressor grid via pin one. The KT77 avoids this. The only caveats are to ensure that your power transformer can supply an extra 500ma of heater current per tube and that the range of bias voltage adjustment is correct. If you have a Marshall amp and find EL34’s too compressed and 6550’s too crunchy the JJ KT77 may be just the ticket.
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NOS Siemens / RFT EL34 - Back when we started doing reviews of EL34 tubes, an old and somewhat tired set of Siemens EL34 was used as the reference standard. To have them available again for what I consider to be a reasonable price is great. These are the real deal. I tested three pair of the NOS tubes with different “perfect pair” matching numbers just to see if there was consistency and I’m happy to report that when biased the same they were very consistent. When I think of German power tubes I think of a big warm sound that doesn’t cause listening fatigue after an hour of playing. Many will say that Telefunken is king but the Siemens brand was always under rated. I ran three different types of EL34 tubes through the Marshall in one night of testing and the Siemens was the only one that required me to reduce the bass response. These tubes are extremely warm sounding and if you have one of those amps that sounds thin at lower volume levels, these should take care of that problem in short order. Midrange response seemed slightly skewed toward the bass side. This is no doubt where the extra warmth is coming from. The high end was smooth and clear without a trace of harshness. Construction is very good with the straight, flat-top bottle that is characteristic of the Siemens EL34 tube. No issues at all with noise and this is likely because of the thick laminated plate structure. You can see how heavy these plated are by examining the four large crimps down each side of the plate. This is a great opportunity to own NOS EL34 tubes without breaking the bank. And based on Siemens track record they should last longer than anything being made today. Home audio, guitar amps and those big old Grundig and Normandy console stereo units will all benefit. Enjoy.
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Shuguang EL34-B - For many years no one would have believed that Chinese tube factories could turn out work of this quality. The construction of this tube is first class, with a well-supported plate structure that rests in a large straight bottle that tapers to a well finished brown base. These tubes represent a very solid piece of construction with almost no mechanical noise and an overall feeling of quality.
The sound is loud and clear with a very nice sonic range. Not excessive in tops, mids, or bass, they are accurately described as well balanced. The sample tested had no audible microphonics and an average background noise level. Harmonic content was rich, lending that pleasant "swirl" and sustain that guitar players crave.
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Sovtek EL34WXT - Sovtek has come a long way with this tube since the EL34G. Construction has been improved greatly reducing mechanical noise. Very good sound but not in the same range as the Svetlana. It seems as if the frequency response has been shifted toward the midrange band. Harmonics are rich and fairly balanced but the high end can get a bit bright. Great in a darker sounding amplifier.
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Svetlana EL34 - The Svetlana is the perfect tube for classic rock. The midrange is very pronounced and the high end is smooth. The bottom end response is not the best, but in a guitar amp it becomes a moot point. In the test amp the mids just rip through the mix. No guitar player is going to get lost in the mix using these bottles. These tubes deliver incredible crunch making them perfect for that ZZ Top, old EVH sound. Seven string down-strokers may not be as pleased because they don't have that crushing deep bottom end. (Note: the amp used for this review was done in a 100 watt Marshall JMP)
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Tungsol EL34B - The Tungsol EL34B is likely to become the #1 choice of currently produced EL34 tubes. The build construction is great all around and the move to welded plates will likely keep “EL34 rattle” to a minimum over time. The manufacturer claims that this tube has a hint of 6L6 in its tone thanks to manipulating the plate impedance. This is absolutely true, but the effect is most notable when playing clean and to a lesser extent when the tube is driven hard. At lower volume settings you hear a very pure balanced tone with a bit of the 6L6 sparkle in the higher frequencies while providing a midrange that is a little less prominent than most EL34 tubes. The tubes were very open and airy. The bottom end was percussive in the 2x12 open back combo. When driven into distortion it starts off a bit crunchy like a 6L6 but as you push it, the sound blooms into that singing EL34 tone with great sustain and modest compression. I love these tubes. Over the years I’ve tested many tubes but this is the first time I’ve had to tell myself to stop playing and get on to the next set!
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Winged "C" / SED EL34 - If you want one EL34 tube that will do anything the Winged "C"/SED EL34 tube is money well spent. There is ample bass response but it is firm and controlled. The mids are smooth and the top end shimmers. Nice swirling harmonic content. The construction of the tube is outstanding and I feel it contributes to the overall performance. Lots of clean headroom from this tube with a smooth transition into breakup. Probably great in home audio applications, but if you want raunch at lower volume levels keep reading.