Putting KT66 Tubes in my Marshall Studio Vintage!
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- Опубликовано: 1 июн 2022
- In this video I compare the stock EL34 power tubes of my Marshall SV20H to KT66 Power tubes (1950s GEC KT66). I'm playing both setups through a 1971 Marshall 1960B 4x12 with G12M25 75Hz Pulsonic Greenbacks using a 2008 Gibson Les Paul R9.
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Both sounded great! I think the biggest factor in the tonal change was that hat upgrade that you made 😉🤣 That adds a warm air to everything you played! God bless and rock on 🎸👍😎
Thanks J, glad to hear it!
Johan is the friend we all wish we had. Hanging out and playing sweet vintage & newer Rock n’ Roll gear all while kicking out the jams.
So, Let’s go…
Kt66 are such badass! Sweet sounding tubes
Johan, you do the stuff we all want to do. Thanks.
Great video as always! Just as a heads up to anyone who's thinking about doing this, it will work, but you need to use matched tubes. The SV20 uses a shared cathode bias resistor, so it is still self-adjusting, but the circuit was designed with the assumption of similar plate current between the tubes (due to the shared resistor).
Thanks Johan! I've been waiting for someone to make this comparison! I've been wanting to swap to KT66s since before getting my SV20... I'm sold!
Thanks! The KT66s are staying here too
@@JohanSegeborn Awesome man! I got some on the way!
I had a pair of GT E34Ls laying around and decided to check them out for fun... They really make the SV20 sound "bigger" imo.
you always make the best content Johan.
Wow! So much fuller sounding with KT66 tubes!
kT66 are always the best. I use them on my own amp builds. Great crunch,better tone and they last forever. Hard to find nowadays the ruby factory burnt down and they had the original GEC equipment. They sold some to groove tubes. And maybe a few other dealers lucky I built up a little stash so I am covered. Great video Johan! Cheers!!
I have NOS Genelex KT66's in my Mick Grabham JTM45 replica. I replaced them with JJ 6L6 power tubes. THEY SOUND IDENTICAL. Not kidding. Same sound without the high pricing.
@@davestephens8033 Hi. I have NOS Genelex KT 66 as well in my JTM 45 built by me. Yes they sound very similar but because of the kinkless triode design you can get a little more clean headroom.
You are my amp's guru! God bless u!
Thanks my friend
I think I heard a slightly more powerful low end with the KT66's, and brighter high end. Or maybe this was because the mids was lower for the 66's?
My impression is that these KT66's have more powerful sound. Always a pleasure to listen to plexis (mini or full size), thanks Johan!
Thanks man, I preferred the KT66s too, so they’re staying there
I can tell that you're really enjoying this little amp. It's on my short list of amps I want to try. Thanks for the vids!!
I slightly preferred the el34's, but both sounded great
Yeah I love it. Hats off to Marshall
Interesting comparison Johan, though I'm hooked on the KT66 tone. I have the same KT66's (1 GEC / 1 Pinnacle working with a GZ34 Mazda and 3 ECC83 by HRS) in my 1966 30w JTM45 Plexi as when I bought it used as a teenager in 1977. The last time I had it serviced the KT66 values were still within 5% of each other ... they are great valves for a FULL sound.
Holy moly! Real 50's Genalex KT66's! Those are probably worth as much as the amp is!
Great tubes indeed :-)
I don’t really understand some of the comments here claiming that the KT66’s sounded warmer…to my ears the EL34’s (slightly) extra warmth was the only real difference here, and my personal preference. I have the SV20 head going through a single 12’ cab (or a 1960A if I feel the need to get loud), and it’s perfect as it is for me.
To be fair though, I’m spoiled because I also have a Marshall Astoria Custom combo (best amp I’ve ever owned by a looong way) to get my KT66 fix. 😍
I really love this channel and really admire how the tests are conducted...the best I've ever watched. However, the same as so many thousands of other 'shootout' comparisons like this, I hardly ever hear any difference at all between the items on test. Whatever subtle difference there might be, pull a drummer and bass player around the guitarist and that subtle difference is long gone and who cares. The most enjoyable part of videos like this is reading the cork sniffing comments that describe the tonal differences as 'more open', or 'less breathy', or a 'bigger soundstage', or a 'more silky midrange' and all that kind of nonsense 😉😊
What an excellent idea
Thanks! It wasn’t mine though 🙂
K66 sounded like they had better note separation in the chords and slightly more meat in the bass end. Not a huge difference, but worth the cost I'd say. Thanks for the video!
great as always, Johan. the El34s were bit nasaly, maybe some Mullards/Teslas would fix it. I definitely dug the Kt66, broader spectrum and great punch. Would be interesting to hear new production Kt66, how those compare. cheers
To use some very technical terms 😊, the KT66’s are less bright with less top end sizzle….but it’s very subtle. Thanks for another great vid.
Hi, the EL34’s had more punch for me and were my choice, I thought they were a tad warmer as well, keep delivering these sweet videos Johan…
If you own a Marshall you should automatically be signed up for this channel! So much knowledge! Thanks Johan for trying all the things we think about doing!
Also so since the amp is cathode biased, it is just plug and play with the power tubes? Swap in whatever you like? I thought about some 5881's. Cheers!!!
I had valve art kt66 in a jtm45 clone which I accidentally left in when I sold it. They sounded really good and cant find them to buy anywhere now. I really want those again to try in my sv20
I've tried every variation of different tubes in my EL34 based amp, NOS, Mallards. JJ's, EH, Ruby Tubes, you name it, but I splurged and got a set of Gold Lions a year or so ago, and I've never heard better tubes! Obviously different amps respond to different tubes differently, and it's all subjective, but I finally found the tone I've been looking for, for like 40 years with these tubes. I think maybe I should get a backup set now that tubes are not available from the Russian factories.
I really like Gold Lions too
KT66 more scooped (less mids) compared to the 34's more mids. The 66 can be nice for clean, but I keep coming back to 34's in all my amps for crunch, having tried 66's in my 70s hiwatts and oranges for a bit. The differences between 66 and 34 are even more obvious in those amps being fixed bias and much higher plate voltage, versus the SV20 cathode bias + low plate voltage, which is gonna be more spongy regardless of tube type just from that
Both sound great. While I can hear the difference I do wonder if there's actually more in it in regards to feel as the player.
The EL34 feels a bit firmer to play but I think the KT66 sounds better
Great ! You should try to compare the KT66 to KT88, they made a bigger difference to my sv20 combo !
Both good
I think kt66 more fendery
Interesting to see if altering bass and treble positions to make each sound identical is possible
How very ironic as I was just speaking with my amp tech about the safety of trying other tubes as I have some nice NOS 6550 tubes I wanted to try. Just yesterday, and this is in my feed today. (They’re definitely listening in). But I think I’ll give it a go as I’ve been looking for more headroom. I jump my channels and have both Studio Vintage combo and head. It’s the combo I’m looking for more headroom as the 10” breaks up quickly. I’ve also gone to a 12au7 in the PI , Sweetened the tone but dropped volume. Ah the search. First comment, but I’ve always enjoyed your demo’s.
I like kt66. I wonder how would it sound combined using two amps...
Hi, Johan!
I watched that video twice, trying to understand the sound. KT 66 is good for riffs and for the grange. ET34 must be good for solos, for "wow" effects, like Kirk Hammett plays. But I would like to hear it on Fender too. KT66 on strats and teles can different!
Thanks Siegfried! I hope to do a bunch of Strat videos of the Studio series too soon together with Simon
both sound good, also have used 6L6
tubes, Norman Mozley
Thanks Norman!
Both are killer but I like the El34 better . They are a little Warmer with more low mids and a softer treble and bass . The KT66 have more upper mids and treble with a firm low end . It's like the difference between pickups with Alnico 2 magnets and pups with Alnico 5 . I prefer the A2
Nobody today makes a GREAT sounding KT-66. The "Gold Lion" are good, but not great. I have always been a fan of that tube, and they run in two of my amps: A JTM-45 clone, and a Marshall Vintage Modern. The EL-34s in my JMP-50 sound amazing though {old Svetlana}. Circuit design determines which will sound best. My guess is that a 1959 would sound glorious with a quad of NOS KT-66.
That famous EL-34 midrange comes through.
I would like to hear it with KT77 tubes .
First chance I get
I have 6CA7 in my SV20H…. Good tubes!
Let's go !!!!!!🤘🤘🤘🤘
Plug in some 6CA7's!!
First chance I get
Thank you Johan for all the SV20 videos you did.
Have you done any mods to your SV20? Did you remove or change the bright cap on the volume 1 pot?
Thank you for a short reply.
Just put some Mullard El34 and Cv4004 preamp tubes in my SV20. Sounds more powerful and organic. Here I kinda like the El34s. More proper girth and roundness. Less splash. A little splash is nice though.
They sound too similar to me to prefer the _sound_ of one over the other. If forced to choose, I'd go for the one that had the better "feel," whatever that means...
Of course, that's from listening to this comparo on my headphones on my computer...who knows what I would've thought if I had been in the room on the day? Or played the amp with the 2 tube types.
was one type more compressed or saggy or spongy than the other? Some other difference(s)?
Either sound great. Love the tone. If you were looking for a 2x12 to go with that amp, which cab would you get? I have the 1x10 combo and have been thinking about the study vintage 2x12 cab or the 1936.
Thanks Isaac, I’d get a vintage JCM800 model 1936 with G12-65 speakers or put vintage Greenbacks in it
@@JohanSegeborn Thank you Johan! You're the best. Appreciate the suggestion-I'll look to get that cab. You're tone is always so great, so I value your suggestion.
Always interesting to hear tube comparisons! Love those KT66 tubes. Johan, what are your thoughts on 6CA7 tubes?
Thanks Jay! I only have those in my 77 JMP 2204 and I love that one but I’ve never A/B tested them with EL34 and KT66
@@JohanSegeborn Very cool - I have them in my plexi - great tubes - love that tone!
@@GCKelloch Very very cool! I just got another pair for my amp (one had failed). EL34s sound fantastic too but love the 6CA7 tone - kinda like an EL34 with a touch of 6L6 😊
Yep. I have a quad of 6CA7’s in my 1977-78?
MusicMan HD130. They’re the really BIG bottle Sylvania’s. I’d hate to have to replace them >>$$. A matched quad of NOS Sylvania’s would probably cost north of $500 today. Crazy times were in.
I really dig those KT66- I a fan of EL34’s but in some circuits they are just too nasal sounding for my liking. The KT66 took away the nasally frequency that grates on me. I’d be interested to hear Johan A/B the KT66 with the 6CA7 too
Is it possible to use 1 of each tube
1 without damaging the amp?
2 yet get good Marshall tones?
Could I go with kt66's in my origin 20c? It's an el34 powered amp. It's not fixed bias though. I know kt77's will work.
I prefer the KT66 tubes. Nice!
Well, guess I have to go out and get a pair of KT66s for my Studio Vintage. Definitely punchier and rounder sounding. Thanks for this demo!
I hope your speakers are all good after that!
Hmmm,, I wonder how my ears/brain would have reacted without the knowledge, that KT tubes in HiFi amps sounds pretty different from EL tubes. 🤪😅
Cheers and thanks Johan,, 🍻😎👍👍
Cheers Irene!
no re-bias needed, did I get that right??? could I also throw in KT88s?
Epic
Glad to hear it!
Nice demo, pretty much proves that vintage tubes just sound better. Its the same thing with my Mick Grabham JTM45. The Genelex KT66's have a sweeter top end, compared to Chinese Lion KT66's.
The main difference here will be the biasing. It's cathode bias, so different tubes that want to see different voltages will be either more hot or more cold. There's no sound difference between tubes when biased the same way. Proof -> look up Jim Lill and his thorough testing video.
KT 66s seem to be longer than EL34.
Does anyone know if they fit in the SV20 housing without any problems?
Great video Johan - I always wanted to hear how KT66's would sound like in my SV20H. It was recommended to me that I do NOT install in the amp because of the distance between the tubes, low voltages and the space inside the box. I would appreciate anyone's view on this. Thanks in advance!
Do it.
Me too!
I've had kt66s in my sv20h for about 2.5 years now with no issues. I didn't change bias or anything. And I leave the high treble volume at 7-8, so nearly cranked every time I play. (With an attenuator but the tubes don't know that)
@@ultratacoRX7 Thanks for your response. I did install KT66's but it kept blowing a fuse that disabled the low wattage mode. I'm thinking it is to do with component tolerances. So I reverted to EL34's
They sound identical to me.
KT66's are basically identical to 6L6 power tubes. I have vintage NOS KT66's in my Mick Grabham built JTM45, and swapping in JJ 6L6 power tubes, they sound IDENTICAL. That was shocking. I wonder how 5881's would sound in the SV20. I have the SV20, but it suffers from PC board sound, and not good sounding headroom. I loved it at first, but it has obvious failings, so I don't play it much.
That's interesting
Thanks
To me the Kt 66 sounds a little bit fuller? But the EL 34 sounds like a perfect Marshall.The question is? How did the notes feel to your fingers?
I will see how you like this my dad had a marshall major with 4 kt88s in it
Maybe a little 'wider' sounding with the KT's, and perhaps more focused with the EL's, but so close that different speakers would make a bigger difference.
The EL34s sounded slightly more compressed to me and for rock I like that better. But both sounded great but EL34s win for me.
Hey Guys - does anyone know the difference between KT66 and 6L6 tubes What amps were the 66's used in ? Thanks for your help !
First JTM45.... they sound like a 6L6 with added mids. I know because my amp for the last 20 years is loaded with NOS GEC KT66s
Hello! I’m from Mexico and recently I get this amp but de current is 230v and In my country the current is 110v. My question is: this amp has any option to change the 230v voltage to 110v with a internal conection? Any years before this happend with another speaker and I only had to change a little wire inside of this speaker. Thanks!
variac try to check it out !
I think the differences are negliable which is surprising because I thought vintage tubes would sound better. They sounded like the modern Marshall branded ones.
They are interchangeable but would you not still need to re bias for the best results
This amp has no bias adjustment. It is cathode biased. Google is your friend....
so i stopped getting notifications from you, left a comment about it on one of your videos a couple of days ago and the notifications returned. youtube AI slowly learning
interesting comparison with clearly audible difference. kind of sounds like the EL34 is sometimes a little more compressed then the KT66. does it feel any difference while playing?
Glad to hear that :-) EL34 is firmer and a bit easier to play with precision but also a bit colder and fizzier
Don't know if this will make sense but the KT66 tubes sound sharper...not punchier or harsh just each note sounds more sharp, cutting ....I like them
haha i want to hear the inward facing speaker now
I thought kt66 were an alternative for 6L6GC tubes along with more heater current draw
Kt66 have a larger frequency range - more musical sounding tubes - beautiful sounding tubes
Sounds better with kt66 to me. I doubt it can damage the amp in any way, so you still use the kt tubes Johann?
Kt66 sound rounder with more presence. Colorful tone brotha! The EL34 seem flat by comparison 🤔
Pretty much the same thanks Johan, maybe just a little more warmth to the KTs but extremely marginal at best. Cheers.
Fairly close… I heard a tiny amount of a mid drop from the kt66s and maybe a little more top end dynamic at times. But the el34s sounded great and I don’t think I would change them
EL34s are certainly good enough
EL34's sound more rock'n roll to me
How would you describe the difference in feel?
The EL34 are tighter and easier to play but colder and fizzier
Interchangeable, but you need to re-bias. Right? Sounds Pretty cool.
Thanks, no as I understood it I didn’t since it’s Cathode biased, but I may be exposing my ignorance here 😆
@@JohanSegeborn oh right! I forgot these are cathode biased. I literally commented about that the other day too. Lol
Even my wahsing machine would sound better with a pair of 50s Genalex KT66!! Hahahaha!
Did you just put the KT66s directly? No changes in the resistor configuration of each valve?
Thanks for the video comparison!
Thanks! 😄 I just swapped them
KT66 rules!!!
Genelec not General Electric lol but that's awesome, a good NOS pair of those can go for 2 grand.
It was my understanding that these tubes are not directly interchangeable....pentode, tetrode thingy. What gives? I'd try it, but research doesn't seem to show this is advisable without some circuit changes. Anyone around?
Traylestrat. I’m no expert but I have been rolling different nos power tubes in amps for many years and I have not run into many problems at all but there are a couple rules to keep in mind…….
Most importantly do a little research on a particular amp and tube before just throwing it in there.
Also you are usually safe running 6l6gc’s and kt66’s in a amp that is designed for el34’s. Not always safe putting el34’s or kt66’s in a 6l6gc amp without a some modifications. Again do some research.
Also I find it’s safer to do this with fixed biased amps with a large enough sweep on the bias pot to run the tube at its recommended plate voltage. The SV20 is cathode biased, so it’s probably running those kt66’s a little hot. But those old gec’s are super sturdy tubes that probably take the higher plate voltage just fine. But eventually they will fail faster than they would running at their optimal plate voltage. You could change the cathode resister to run the different type tube to optimal voltage. That’s probably what I’d do if I decided to keep those tubes in that amp. Especially since those particular tubes are worth $600/1000 a pair. Even though I have a closely matched high testing pair I found a few years ago for $350. Remember of the three main (40/50 watt per pair) guitar power tubes, el34’s are the hottest, 6l6gc’s are the coolest and the kt66’s are a middle ground.
Also it’s better to do this with a good amp with overspec’d quality transformers and good tubes with plenty life left. And constantly monitor the heat coming off the transformers and watch that the tubes don’t start red plating. If so, immediately shut it down. Hope this helps
Not enough of a difference to really matter imo. Maybe the feel is better one way or the other?
Have you looked at the price of vintage tubes they cost more than the amp
The point where you have out-experimented the experiment!
I love my EL34's but I really likes the KT66's. Worth trying a swap, I like the thicker/mature sound of the KT^^
Thanks!
now how about kt88s?
So you don’t have to do any biasing with the kt66 in SV20h ?
The SV20 is cathode bias... Plug and play.
Dig the warmth from those KT-66s and also your hat ;)
Thanks Andy! 😄
For rock el34
Johan, Check with Marshall before using Kt66 valves in SV20, I don't think it is advisable, too many mismatches I believe,it will work apparently but not for long I have been informed.
EL34 everytime.
KT66 sounds a bit fatter and rounder to me. Very Nice!
Thanks! I prefer them too
KT66's pull about 50% more current on the heaters, i wouldn't leave them in too long, just a word of caution.
The amp has been DESIGNED to run kt66 along with all of the like pinned tubes.
Distortion was the same. KT has a harsher tone, EL sounded creamier.
KT66s were definitely had more body - and so better - to my ears. Thanks Johan.
That's a cool swap but to my ears it sounds like nothing the tone can't also be changed using the tone controls to shape.
They are similar indeed, but the 66s are more natural sounding to me
@@JohanSegeborn true you are hearing it up close and personal and I'm hearing it on my cellphone 8,000 miles away from your room haha!
Will KT88's fit/work?
I've since learned they won't
@@counterbalancelife4305 different sockets, if I'm not mistaken
For blues kt66
kt77 are huge and fat tone .yeahhhh nice one from the king of tone.
Thanks!
EL34s warmer