Members Gwimlock Posted April 16, 2012 Members Share Posted April 16, 2012 Hey everyone, I'm seriously considering switching to KT66s in my JCA50H, as the 6L6 pair I've currently got installed are finally on their last legs. First, I'm wondering about tube recommendations. Second, I'm wondering about EXACTLY what needs to be done for the tube change. I won't be doing it myself, though my friend and bandmate has offered to do the switch. While he's never rebiased as amp himself, he does regularly do pedal construction and all the guitar-related electrical stuff for my band and friends, and he insists that it won't be a problem. (Better for him to buy a bias probe once, he says, than to pay an amp tech to do the job repeatedly.) Yes, I'm probably asking for trouble by having a non-certified tech do the job. Your thoughts? Link to comment Share on other sites More sharing options...
Members koen77 Posted April 16, 2012 Members Share Posted April 16, 2012 They will work with the same bias settings, but you should look up on the internet and maybe try it yourself. Get a bias tool like the weber bias rite. I did it myself and i am very pleased with the results. As for switching tubes, that's a no-brainer. Fastredponycar has a vid up on youtube where he changes to kt88 tubes and adjusts the bias. I based myself on that video. Link to comment Share on other sites More sharing options...
Members guitarbilly74 Posted April 16, 2012 Members Share Posted April 16, 2012 KT66 on the JCA? Just pop them right in, you don't even have to take the amp out of the headshell. Link to comment Share on other sites More sharing options...
Members Gwimlock Posted April 16, 2012 Author Members Share Posted April 16, 2012 Man, that's the best news I've gotten all day. Thanks, guys! Who makes your favorite KT? Link to comment Share on other sites More sharing options...
Members LA-Ü-RA Posted April 16, 2012 Members Share Posted April 16, 2012 You can use KT66's in that amp. I currently have JJ's in mine. However, you should still check/set the bias on that amp when changing power tubes. Link to comment Share on other sites More sharing options...
Members guitarbilly74 Posted April 16, 2012 Members Share Posted April 16, 2012 Man, that's the best news I've gotten all day. Thanks, guys! Who makes your favorite KT? JJ's are pretty good and not too expensive. Link to comment Share on other sites More sharing options...
Members GRIMESPACE Posted April 16, 2012 Members Share Posted April 16, 2012 Seriously relevant to my interests... please let us know what you think when you do the switch! Link to comment Share on other sites More sharing options...
Members Northstar Posted April 16, 2012 Members Share Posted April 16, 2012 I asked the exact same question to my amp tech two weeks ago. Here's his answer: When you replace 6L6 by KT66, the transformer and the wiring inside will get "stressed" by trying to get more voltage to the KT66s (KT66s require more current than 6L6s). The transformer will age prematurely with a possibility of failure. He told me I run the risk of burning the transformer. It would be like asking a car to tow a camping trailer all year long. Two weeks a year is ok but it's not like asking a car to carry a bigger load 12 months a year. It should work but with a distinct possibility of transformer failure sooner than later. Link to comment Share on other sites More sharing options...
Members Gwimlock Posted April 17, 2012 Author Members Share Posted April 17, 2012 I asked the exact same question to my amp tech two weeks ago. Here's his answer:When you replace 6L6 by KT66, the transformer and the wiring inside will get "stressed" by trying to get more voltage to the KT66s (KT66s require more current than 6L6s). The transformer will age prematurely with a possibility of failure. He told me I run the risk of burning the transformer. It would be like asking a car to tow a camping trailer all year long. Two weeks a year is ok but it's not like asking a car to carry a bigger load 12 months a year.It should work but with a distinct possibility of transformer failure sooner than later. Yeah, I emailed JCA and Dan said pretty much the same thing: "The JCA50H is designed to operate with 6L6 Link to comment Share on other sites More sharing options...
Members BC Audio Posted April 17, 2012 Members Share Posted April 17, 2012 I'm surprised JCA is talking about the output transformer. It's the power transformer that could be stressed by KT66s. A KT66 draws 1.3A of heater current. A 6L6 draws 0.9A. So two KT66s draw 2.6A, while two 6L6s draw 1.8. That's a significant difference. I have always liked Valve Art KT66s. That's what I supply with my Amplifier No. 9. Link to comment Share on other sites More sharing options...
Members Jack Tone Posted April 18, 2012 Members Share Posted April 18, 2012 You might check out the Sovtek and Tungsol Kt66's. Here's a review: http://thetubestore.com/kt66reviews.html I'm not sure if they're "true" KT66's but apparently they draw the same current as 6L6GC's. Link to comment Share on other sites More sharing options...
Members jdog1 Posted April 18, 2012 Members Share Posted April 18, 2012 Hey everyone, I'm seriously considering switching to KT66s in my JCA50H, as the 6L6 pair I've currently got installed are finally on their last legs. First, I'm wondering about tube recommendations. Second, I'm wondering about EXACTLY what needs to be done for the tube change. I won't be doing it myself, though my friend and bandmate has offered to do the switch. While he's never rebiased as amp himself, he does regularly do pedal construction and all the guitar-related electrical stuff for my band and friends, and he insists that it won't be a problem. (Better for him to buy a bias probe once, he says, than to pay an amp tech to do the job repeatedly.)Yes, I'm probably asking for trouble by having a non-certified tech do the job. Your thoughts? If you have a multimeter and bias tool it's an easy switch. I did it with my JCA50H and there was a slight adjustment I had to make. But honestly, the difference between the two tubes is pretty slight. While the KT66 produces a little more bass and seems to offer a little more head room, I eventually switched back as the 6L6's just sound better in that amp. I used JJ's for both. Link to comment Share on other sites More sharing options...
Members Phrophus Posted April 18, 2012 Members Share Posted April 18, 2012 I swapped out the stock 6L6's in my Engl thunder with Gold Lion KT-66's and me and a friend rebiased it. It would have worked without rebiasing, but I wanted to try it. Huge improvement in the sound of the amp. Link to comment Share on other sites More sharing options...
Members Gwimlock Posted April 18, 2012 Author Members Share Posted April 18, 2012 I decided not to mess around with KT-66s yet. Between the concern about component life and the fact that the only power tubes I've had in the amp have been the stock Chinese 6L6s and later, a well-worn set of Mesa STR 430s. The latter type, most of you know, is just a rebranded Sovtek 6L6WXT+, which is neither the best or worst choice for a 6L6. I instead bought a matched pair of SED Winged-Cs, based on the absolutely GLOWING reviews from, well, pretty much everyone and their mother. While people seem to either love or hate JJs, Sovteks, etc., there's really been nothing but positive comments about the Winged Cs, so we'll see how that goes. I can always switch to the KT66 later, but seeing as how the Winged Cs are the same price, I may as well start here. Thanks, everyone! Link to comment Share on other sites More sharing options...
Members shane159 Posted April 18, 2012 Members Share Posted April 18, 2012 The winged C's are my favorite tube, hands down. They are higher but it is very worth it IMO. Huge bottom and super clear!! Link to comment Share on other sites More sharing options...
Members guitarbilly74 Posted April 19, 2012 Members Share Posted April 19, 2012 I decided not to mess around with KT-66s yet. Between the concern about component life and the fact that the only power tubes I've had in the amp have been the stock Chinese 6L6s and later, a well-worn set of Mesa STR 430s. The latter type, most of you know, is just a rebranded Sovtek 6L6WXT+, which is neither the best or worst choice for a 6L6. I instead bought a matched pair of SED Winged-Cs, based on the absolutely GLOWING reviews from, well, pretty much everyone and their mother. While people seem to either love or hate JJs, Sovteks, etc., there's really been nothing but positive comments about the Winged Cs, so we'll see how that goes. I can always switch to the KT66 later, but seeing as how the Winged Cs are the same price, I may as well start here.Thanks, everyone! FWIW, I tried a lot of tubes on my JCA100 and the 6L6WXT are the ones that sounded the best. It's also what Mike Soldano recommended to me when I spoke to him, he also uses them as OEM equipment on his Soldano line. Link to comment Share on other sites More sharing options...
Members Gwimlock Posted April 19, 2012 Author Members Share Posted April 19, 2012 FWIW, I tried a lot of tubes on my JCA100 and the 6L6WXT are the ones that sounded the best. It's also what Mike Soldano recommended to me when I spoke to him, he also uses them as OEM equipment on his Soldano line. Billy, I heard about Soldano's preference for the 6L6WXT as well. The Mesa/Sovtek was definitely a huge improvement over the stock tubes, but I thought I'd try something different, and supposedly "better". It remains to be seen (or heard, rather) if the Winged Cs will be my favorite. My bandmate has a 68 Fender Dual Showman that needs new tubes as well, and he's considering replacing the current GTs with JJs. At least we'll be able to switch the tubes back and forth to see which amp sounds best with what tube. Link to comment Share on other sites More sharing options...
Members guitarbilly74 Posted April 19, 2012 Members Share Posted April 19, 2012 Billy, I heard about Soldano's preference for the 6L6WXT as well. The Mesa/Sovtek was definitely a huge improvement over the stock tubes, but I thought I'd try something different, and supposedly "better". It remains to be seen (or heard, rather) if the Winged Cs will be my favorite. My bandmate has a 68 Fender Dual Showman that needs new tubes as well, and he's considering replacing the current GTs with JJs. At least we'll be able to switch the tubes back and forth to see which amp sounds best with what tube. Cool, let us know what you think. I tried the WXTs, C's, some old GT's, JJ's, Ruby's and the stock ones. I ended up liking the WXT the better. Link to comment Share on other sites More sharing options...
Members Gwimlock Posted April 23, 2012 Author Members Share Posted April 23, 2012 Well, I got the C's from TubeDepot specifically because I also wanted to order a bias probe and multimeter at the same time, but the Bias Rite was on backorder. (Next time, I'll order from Laura at Valvequeen for sure, as we're both in Ohio, and I'm a fan of supporting local [or close enough] businesses.) The C's sound huge, super spongy, and mmmmmaaaybe a little bit cleaner, but I'm not too sure. Time will tell. They're great, for sure, but are they $30 better than, say, the JJ's? I'll have to wait for my buddy to pick up a pair of JJs so the switching can begin! Link to comment Share on other sites More sharing options...
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