Differences Between 6L6, EL34, & KT88 Tubes

What are the basic differences? I know there's still a bunch of differences between brands and specific models but I'm looking for the basic overview. Which would be considered to have the most clean head room or slowest break-up? Where do each fall in the gain spectrum, from high to low? Are these all interchangable in an RM100 amp?


Thanks in advance.

I'll do the best I can here. In general, EL34's have a very pronounced mid range. Think of that classic Marshall crunch sound, thats the EL34 sound. 6l6's have a more pronounced low end and subdued mids. I've not heard many KT-88's but from what I've read they have HUGE low end plus mid range curnch, kind of like if you took a big 6l6 and an EL34 and combined them.

www.tubedepot.com and www.tubestore.com both have reviews were they compair different brands of each class of tubes

I recently stumbled across this when researching alternate power tubes for my Rocktron Vendetta... hopefully this is of some help to you...

http://bellsouthpwp.net/r/i/ricjohns/Rivera%20Power%20Tube%20Guide.htm

--B

bduersch said:

I recently stumbled across this when researching alternate power tubes for my Rocktron Vendetta... hopefully this is of some help to you...

http://bellsouthpwp.net/r/i/ricjohns/Rivera%20Power%20Tube%20Guide.htm

--B

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Noteworthy about Hendrix is his JTM-45/100 had KT-66s which are much like 6L6s in many respects. Personally I find EL-34s a bit hard and grindy. I would definately recommend 6L6s with British sounds for a more mellow timbre.

First here is what I own currently... Koch Multitone 2x12 combo, Soldano Hot Rod 50 Marshall Slant with greenbacks, Randall Lynch Box. It is worth noting that I own approx... 200 tubes. I've owned 2 JCM 800's in the past, a small marshall 1x12 and some Fender and Peavy amps.

EL34 are that classic British sound which is signified with a top end sparkle, mids that are voiced round and a large warm bottom that can be fartty if your not carefull. Attack is more relaxed spongy. There is a 3 D quality and a wideness to the overall frequency spectrum... a big wall of sound. EL34 tend to sound BIG and loud but not project as well as 6L6.

6L6 are that classic American sound with a tight focused top with less sparkle and more edge, mids that are very pronounced and voiced in the upper mid freqs, a bottom that is tight and punchy. Attack is razor sharp.
There is a very focused sound to the overall frequency spectrum. 6L6 project very well and do not have that BIG wide sound like EL34.

Hope this helps.

Khing

khingpynn said:

First here is what I own currently... Koch Multitone 2x12 combo, Soldano Hot Rod 50 Marshall Slant with greenbacks, Randall Lynch Box. It is worth noting that I own approx... 200 tubes. I've owned 2 JCM 800's in the past, a small marshall 1x12 and some Fender and Peavy amps.

EL34 are that classic British sound which is signified with a top end sparkle, mids that are voiced round and a large warm bottom that can be fartty if your not carefull. Attack is more relaxed spongy. There is a 3 D quality and a wideness to the overall frequency spectrum... a big wall of sound. EL34 tend to sound BIG and loud but not project as well as 6L6.

6L6 are that classic American sound with a tight focused top with less sparkle and more edge, mids that are very pronounced and voiced in the upper mid freqs, a bottom that is tight and punchy. Attack is razor sharp.
There is a very focused sound to the overall frequency spectrum. 6L6 project very well and do not have that BIG wide sound like EL34.

Hope this helps.

Khing

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This sounds right on the money to me! One thing Im wondering because my last few amps have been 6L6 based and now my MOD 50 is EL-34s...When you say 6L6s project well, do you mean that they cut better than EL-34s because of the focused upper mids?

Matt

When you say 6L6s project well, do you mean that they cut better than EL-34s because of the focused upper mids?

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Yes that is exactly what I mean.

An easy way to reference is the Soldano trademark tone... Until the Avenger Soldano amps were exclusivly 6L6. The Avenger is their first EL34 amp. Mike Soldano says that the Avenger is basically a Hot Rod 50 plus with EL34 power amp tubes.

I just sold a 1983 Marshall JCM 800 4104 ( 2x12 combo ) great amp but not quite the sound I look for. It was modded and the preamp section ran hot with a ton of gain on tap. It had a big almost harsh top with muddy lows but nice mids... go figure. i ran Svetlana EL34 in it. They were the only thing I could get that reduced the harsh frequencies of the amp.

One other thing to remember is how biasing effects tone... 6L6 typically bias at 28 - 35ma and EL34's typically bias at 30 - 38ma. The hotter the bias the quicker the tubes break up but also the attack softens up. The colder the bias the tighter the attack and the more brittle the distortion will sound. Ofcoarse this is to a point and within a useful musical range.

Craig

Craig,

I know exactly what you mean. My EL-34 MOD 50 does not cut like my SLO does and my Vox channel breaks up very very early. Maybe Ill try some 6L6s in there. Its so easy since the MOD 50 has external bias points.

Thanks!
Matt

External bias points are the ticket bro. Most modern amps have trim pots with a wide enough range to properly bias El34 and 6L6 along with many other octal base tube types... ie; KT66.

For instance Randall Lynch Boxes and other 100 watt MTS amps have the ability to have a two and two tube arrangment. for example in tube slot #1 a 6L6, in #2 a EL34, in #3 a EL34 and in #4 a 6L6. Since they use a 1 ohm resister in the cathodes of the output tubes for the applied physics... now mv = ma... biasing each tube properly to it's spec is simple.

With the Koch I can do the same but I have to take the head out to reach the test points and trim pots. With the Soldano I cannot because they do not use the 1 ohm resister on the cathode. For amps like that I recommend a Weber Bias rite tool. Still fo rthe Soldano I have to again remove the head to get at the trim pots.

Try a pair of 6L6 and a pair of EL34's some time... I run my Koch that way... the results are very interesting and give you a truely unique tone.

I think you will find that a pair of 6L6 tubes for you 50 might just be the ticket. I recommend that you try Sovtek 5881WXT ( 6L6 ), jj 6L6, or Groove Tubes GT6L6CHP Blackplates. I'm running the GT6L6CHP Blackplates in my Soldano right now. I picked a bias rating of 7 so they are in the cleaner end of "normal" breakup ( 4-7 ). I bias them on the hot side of the range to allow them to clip earlier but maintain quick attack.
I scope bias everything.

Khing

Yeah man, I posted this in another thread, but today I took two Sovtek 5881s out of my SLO and dropped them in the MOD 50. I biased at 34mV and the amp feels much more at home for me next to the SLO. Definitely a tigher attack, more clarity and punch. It feels stiffer but I like it probably because Im used to it. The Vox isnt as Voxy but still sounds **** good. Thanks for the tips!

-Matt

Cool bro it's all good... partof the whole Vox thing is that "looseness".

Craig