KT77 or KT66 in my amp?

Manhell

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hello there,

my question is, can I swamp the 6L6s in my road king for KT77 or KT66? if so what will be the consequences of the sound and if it is relevant in the sound.

any hint will help

Thanks
 

loktide

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hello there,

my question is, can I swamp the 6L6s in my road king for KT77 or KT66? if so what will be the consequences of the sound and if it is relevant in the sound.

any hint will help

Thanks

KT66 are direct replacements for the 6L6GC, afaik. they're also quite close tonewise.

i have no experience with KT77s
 

Underworld

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KT77 are a direct replacement for EL34 type tubes. You should be good to go, as long as you use the right replacement type on the right type!

As for the sound, a KT77 is a beefed up EL34 - it should sound a bit more toward a 6L6. The opposite goes for the KT66 - it's a 6L6 with a british vibe. It WILL sound different, but not that much. Best thing to do is to try, record some clips and share them with us!
 

Manhell

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Nice, thanks for your help. just one more thing, considering that the amp is a Road King, will I mess the original sound of it, or will I increase its potencial?
 

USMarine75

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^ It's more like different flavors. For example... you can buy a Peavey 6505 with 6L6 or EL34. Neither is better, especially since tone is subjective. But the 6L6 has the more American sound and the EL34 has more of a compressed Brit sound. Both good... just different.

The KT66 is related to the 6L6 and the KT77 is related to the EL34 tonally. They are the Kinkless Triode (hence KT) versions. From my understanding the KT versions have more headroom / breakup later, which is why you see them more in hi-fi equipment and less in low-fi (metal guitar amps). You often hear people talking about the bell like chime of the clean channels on KT tube amps. They often have ridiculous SPL levels without any distortion, so you really have to push them hard to get distortion. When you do it is usually creamier than you find in a 6L6/6V6/EL34 powered amp which is "grainier".

FWIW since the KT77 is based on the EL34, I'd expect it to have that Marshall based sound... with good high volume clarity and less harsh 6L6 fuzziness.

Also, it REALLY depends on amp design. Although basically all amps use preamp and poweramp tubes to generate their distortion, some focus on the overdrive of the power tubes, while others slam the shit out of the power tube by cascading a mass of high gain preamp tubes (e.g. Peavey 5150/6505).

Here's a another good site about tubes:

GM Arts - Guitar Amplifiers
 

wakjob

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KT66's are in the 6L6 family. But get them from a good dealer that will work with you and your Mesa. It's got a selector switch for EL34 OR 6L6 right?

You'll need to get a set of tubes with to correct transconductance/current draw for that amp.

P.S. If I remember right, the KT66's will breakup just a bit faster than others in the same family. But that is for old/classic circuits, Don't put too much emphasis on OUTPUT TUBE distortion in modern amps, they just aren't designed that way. Don't believe me, plug your guitar straight into the FX loop return and crank it. Most amps nowadays are clean as a whistle. What most people are hearing when they turn their amps up is the PHASE INVERTER starting to overdrive.
 

USMarine75

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Most modern high gain amps get their distortion from combination of phase inverter, cascading preamp tubes and slamming the front end, and power amp breakup. Depends on the manufacturer which is predominant. For example, Peavey 5150/6505 slams the front end with crazy cascading 12AX7 preamp distortion even at low volumes. Preamp distortion is usually more odd order harmonics and harsh vs the power tube distortion which is more even order and creamier. But most modern amps combine the two in various forms which is why everyone has a signature tone.

My advice... go with your ears. If you like it then rock it... And record us a clip! ;)
 

Manhell

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It is a Road King, it already has 6l6 And EL34 inside so each power tube has is place.

I just wanted to have a better clean and a nice articulated sound I know that the 6L6 and KT66 are alike, I just wanted a tube to improve the sound.

I think that the distortion is coming from the cascading 12AX7s of the preamp and most of Mesa's power amps are clean and powerful, and probably I need to change the 6L6 but I wanted to do it right because I play 8 strings too and I need it to take it especially on the cleans.

Also I have a Mesa 50/50 power amp, can I use yellow sockets in one of the channels to put some EL84?
 

budda

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It is a Road King, it already has 6l6 And EL34 inside so each power tube has is place.

I just wanted to have a better clean and a nice articulated sound I know that the 6L6 and KT66 are alike, I just wanted a tube to improve the sound.

I think that the distortion is coming from the cascading 12AX7s of the preamp and most of Mesa's power amps are clean and powerful, and probably I need to change the 6L6 but I wanted to do it right because I play 8 strings too and I need it to take it especially on the cleans.

Also I have a Mesa 50/50 power amp, can I use yellow sockets in one of the channels to put some EL84?

How old are the tubes in it now?

"better cleans" and "articulate sound" sounds like a power section retube, fresh strings, a set-up (adjusting pickup heights included), and some EQ'ing.

The tubes may not be a "magical" answer.
 

Manhell

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How old are the tubes in it now?

"better cleans" and "articulate sound" sounds like a power section retube, fresh strings, a set-up (adjusting pickup heights included), and some EQ'ing.

The tubes may not be a "magical" answer.


Yes indeed, I'm guessing the power tubes could have around 5/6 year and the guitars are already taken care of, so since I got it used I think it needs the retubing.

Also is my first time with rectifier tubes, should I need to change them too? cause there's no signal passing through them so I suppose they're good
 

budda

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You can - there is a noticeable change, but I don't think it's that massive. AVWII on here totally retubed his triple rec, and he noticed a change but I don't think it was a night and day kind of thing.

5-6 years, I'd do the power section first then wait and see if you think it warrants the preamp section too.
 

neotronic

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Most modern high gain amps get their distortion from combination of phase inverter, cascading preamp tubes and slamming the front end, and power amp breakup. Depends on the manufacturer which is predominant. For example, Peavey 5150/6505 slams the front end with crazy cascading 12AX7 preamp distortion even at low volumes. Preamp distortion is usually more odd order harmonics and harsh vs the power tube distortion which is more even order and creamier. But most modern amps combine the two in various forms which is why everyone has a signature tone.

My advice... go with your ears. If you like it then rock it... And record us a clip! ;)

usualy it's exactly the other way. Preamp gives usually even harmonics, as all the tubes operate in class A. But the poweramp runs in class A/B (all of the 20W or larger amps), which always gives you mostly odd order harmonics no matter what.
 

lemeker

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How old are the tubes in it now?

"better cleans" and "articulate sound" sounds like a power section retube, fresh strings, a set-up (adjusting pickup heights included), and some EQ'ing.

The tubes may not be a "magical" answer.

I agree with this.

I did sort of the same thing with my Dual Rec. I wanted sparkly jangly clean cleans (not that the mesa isn't capable already) that I wasn't getting from the el34's, so I switched to 6l6's, and it did the trick.

The tubes will improve the sound but will not change the way it sounds. Meaning.....that my recto still sounds like a recto regardless of the tubes, but the tube choice changed some of the nuances. I don't have the brittle grainy el 34 sound, but a round wholesome sound with my 6l6's (my views based on my playing only).

Changing the rectifier tubes will tighten up the amp just a tad, and remove a bit of sag....but not like a boost will. I noticed a minimal difference, enough to where it made the purchase worth it to me
 

Manhell

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I know it will not change the sound of the amp, I just want to give it new life and probably it has a sound a little bit worn off by the years of the tubes
 

USMarine75

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usualy it's exactly the other way. Preamp gives usually even harmonics, as all the tubes operate in class A. But the poweramp runs in class A/B (all of the 20W or larger amps), which always gives you mostly odd order harmonics no matter what.

Woops... the tone description was right but I think I was thinking odd for "odd" sounding and got it backassward. Yeah they both actually create both types of harmonics, but the preamp creates mostly even... and the power tubes create mostly odd, because the even cancel out. It's been awhile since I took basic electronics and the military stopped using tubes awhile ago anyways.

tl;dr... F it, by a Kemper/Axe-FX and quit worrying about tubes.
 

Manhell

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Woops... the tone description was right but I think I was thinking odd for "odd" sounding and got it backassward. Yeah they both actually create both types of harmonics, but the preamp creates mostly even... and the power tubes create mostly odd, because the even cancel out. It's been awhile since I took basic electronics and the military stopped using tubes awhile ago anyways.

tl;dr... F it, by a Kemper/Axe-FX and quit worrying about tubes.


AHAHA, already got an Axe Fx that's why I bought the road king so I can have a real tube amp and a "fake" tube amp
 

dunwichamps

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kt66s not exactly a drop in for 6l6s, they have a different plate impedance and this will change your output tap secondary impedances.

I have used JJ Kt66s before, they have a big glass envelope as large as their Kt88s so space might be needed if your amp is cramped. they bias up the same tho. tone wise, somewhat like 6l6s but they have a bigger lower end and a very sweet sound but YMMV.
 


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