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Power Tube Descriptions
Eurotubes - JJ Electronic EL84
JJ Electronic EL84 Factory Data Sheet: EL84   Factory description: Gold plated control grid for improved fidelity and a plate dissipation of up to 12 watts. Our observation: We’ve compared these to all of the classic European EL84’s, U.S. 6BQ5’s and the current Russian EL84’s. The JJ’s seem to fall right between the Philips 6BQ5’s and the Mullard EL84’s. Very smooth with a sweet chime, a very defined mid and tight punchy low end. Overall, one of the best EL84’s we’ve ever heard.  Mike Zaite of Dr. Z amps gave the following review of the JJ EL84 " The JJ tubes are long lasting, strong and give increased power output. This tube excels in headroom and balls. Great rock tone, punchy, with a strong attack." The JJ EL84's were reviewed by Dick Olsher on enjoythemusic.com in a review of the Manley Labs Stingray amp where they stated the following. " The end result was a definite WOW! The sound of the Stingray was transformed into a darker and richer sonic life form."
Eurotubes - JJ Electronic EL844
JJ Electronic EL844 Factory Data Sheet: EL844   Factory description: Gold plated control grid for improved fidelity and a plate dissipation of up to 9 watts. Our observation: In 2009 we asked our good friends at JJ Electronic to build us a low power EL84 and they agreed to do it! It's not an easy task to build a tube that has never been built, but JJ has proven they are the people to do it. The new JJ EL844 is an entirely new tube that dissipates 9 watts and is a drop in replacement for EL84's in most all amps. It has a very smooth sweet breakup just like the JJ EL84 and it will breakup a couple decibels earlier.  These will drop into most cathode and fixed biased amps like the Orange AD amps, VOX AC amps, Laney VC amps, Crate V and VC amps including the Palomino, Budda amps, Fender Blues and Pro Junior amps. It is also an option for all the 5 watters like the Valve Junior, Blackheart, Mini Cat and others. If your amp is adjustable bias like the Marshall 201 and 401 or Bugera V22, Jet City or Carvin then because the EL844's dissipate 9 watts these must biased 25% lower than standard EL84's. For those of you who are familiar with the old EL83, the EL844 plate structure is quite similar but the EL844 is NOT a replacement for an EL83!!! It is quite different.
Eurotubes - JJ Electronic EL34
JJ Electronic EL34 Factory Data Sheet: EL34   Factory description: Gold plated control grid for improved fidelity. Our observation: This tube is as close to an NOS Mullard as you can get. They are very smooth and have the biggest low end of any current production EL34. We still prefer the JJ E34L for most applications simply because of it's extended low end and the fact that it's tighter and punchier, but if you’re after a real vintage EL34 tone then these tubes will take you there.
Eurotubes - JJ Electronic E34L
JJ Electronic E34L Factory Data Sheet: E34L Factory description: Gold plated control grid for improved fidelity. Special plate alloy improves plate dissipation as compared to the standard EL34 resulting in stable performance at higher power levels. Our observation: This tube has about 20% more head room than the standard EL34 and it also has a deeper, tighter low end. The E34L is also a bit punchier and more aggressive than the standard EL34 which makes it a great tube for Matchless, Bogner, Carvin, Peavey and all Marshall amps. The JJ EL34, E34L and the JJ KT77 are the only EL34 type tubes that we have found that will stand up to the 700 plus plate volts found in the Musicman HD 130 amps.
Eurotubes - JJ Electronic KT77
JJ Electronic KT77 Factory Data Sheet: KT77   Factory description: Gold plated control grid for improved fidelity. Special plate alloy to improve plate dissipation. This is a hand aligned Beam power tube resulting in stable performance at higher power levels. Our observation: The story behind this tube is that it was made by JJ at our request after meeting with them. We quietly sacrificed a pair of our original GEC KT77 for them to test and then break apart (while Bob wasn't looking) to reverse engineer. The result is a stunning new production KT77 that has all the qualities we coveted in the original. The JJ KT77 has a slightly deeper low end than the JJ E34L and they have a nice sizzle on the top end without getting brittle and the mid range harmonic structure is very complex. The clean tone is very fat and full and the when driven to saturation the crunch has more of a chunk to it. We LOVE these in Marshall DSL's, TSL's and JVM's! (See the Retube Kits in the online store) We also use a lot of them in Peavey XXX and JSX amps. They are also one of our fave's in Mesa Rectifier amps that can accommodate EL34's if you're after a British sound. The impedance of these tubes more closely matches a 6L6GC and is higher than the impedance of an EL34 so if you have a specific application which is an EL34 only circuit please contact us about using them. These are also great in most vintage and current production Hifi applications as you can tell by some of our customer reviews.
Eurotubes - JJ Electronic 6CA7
JJ Electronic Big Bottle 6CA7 Factory Data Sheet: 6CA7  Factory description: Gold plated control grid for improved fidelity. Special plate alloy to improve plate dissipation. Our observation: The JJ Big Bottle 6CA7 is another welcome addition to the already extensive line offered. It has the harmonic complexity of an EL34 in the upper mids and highs and the round low end of a 6L6 so it's as close to mixing an EL34 with a 6L6 in one bottle as you can get. We just loaded up Marshall DSL50 with a pair of these and and the first word that came to mind was "woolly". The low mids were FAT, and the high end sparkle was outstanding! These are a great "in-between" tube for the Peavey XXX and JSX amps as well as just about any other EL34 type amp such as Marshall, Laney and Mesa to name a few.
Eurotubes - JJ Electronic 6V6S
JJ Electronic 6V6S Factory Data Sheet: 6V6S Factory description: Gold plated control grid for improved fidelity. Special plate alloy improves performance over any 6V6. This tube has the ability to handle 450 plate volts in triode mode and 500 plate volts in pentode mode! Our observation: This tube has spectacular performance capabilities! This is truly one of the best 6V6 tubes we have ever auditioned. They have a amazing low frequency extension without getting boomy and a high end much like an RCA until they get into saturation where they are more like the old Sylvania 6V6's only fuller and a bit more focused. Absolutely wonderful in Deluxe Reverbs!  These are also just the thing for Fender Hotrod Deluxe amps if you want less power and an earlier breakup. The JJ's can handle the plate voltages with ease!  DO NOT try this with the sovtek or the EH or new tungsol 6V6's, these are all sovtek tubes and cannot handle the higher plate voltages.
Eurotubes - JJ Electronic 7591S
JJ Electronic 7591S Factory Data Sheet: 7591S Factory description: Gold plated control grid for improved fidelity. Our observation: Finally a real 7591! This tube will out perform most all original 7591's and is a drop in replacement.
Eurotubes - JJ Electronic 6L6GC
JJ Electronic 6L6GC Factory Data Sheet: 6L6GC   Factory description: Special plate alloy material and gold plated control grid. Plate dissipation of up to 30 watts. Heavy gauge glass. Best sounding 6L6 ever made replacing all 6L6/5881 tubes in all applications. Our observations: This tube is a work of art! And it sounds as good as it looks. The lows are deep, big and round. The mids are very harmonically rich and natural while the highs are thick, creamy and very detailed. This is the tube for Peavey, Fender, Mesa, Soldano, Bogner ect. We have run these tubes in place of 7027A’s in the old Ampeg gear at 600 plate volts with no problem.  We also stock the JJ 7027A for you guys that just have to have them.
Eurotubes - JJ Electronic KT66
JJ Electronic KT66 Factory Data Sheet: KT66   Factory description: Gold plated control grid for improved fidelity. Special plate alloy to improve plate dissipation. This is a hand aligned Beam power tube resulting in stable performance at higher power levels. Our observation: These are a wonderful addition to the JJ line and it's great to finally have a real new production KT66 that has all of the sonic qualities of the original! A very thick and rich sound with lots of harmonic complexity and a wonderfully smooth breakup when driven into saturation. These are killer in the Dr Z RT 66. We have been sending these to Mike at Z for a while now and he loves them! We are also using these in Mesa Dual and Triple Rec's all by themselves and in combination with KT88's and 6L6GC's. We have researched the proper grades to get the bias right where is should be with no bias mod. You can find kits in the online store! In case you have heard horror stories about the metal bases being connected to a pin and causing shorts, the culprits are the sovtek KT88 and KT66 tubes. This is NOT the case with the JJ Electronic KT66's and KT88's where the bases are isolated as they should be.
Eurotubes - JJ Electronic KT88
JJ Electronic KT88 Factory Data Sheet: KT88  Factory description: Has more power, a wider frequency response and dynamic range than any other KT88/6550 on the market. Gold plated control grid for improved fidelity. Specially designed heat dispersion wings on the plate add more performance, stability and allow plate dissipation up to 50 watts. Our observations: THIS TUBE IS THE BOMB!! Bob uses these tubes in most of his old SUNN gear. They are extremely thick and rich sounding with no loss of high end like the chinese made KT88’s. Any amp using 6550’s can also use the JJ KT88’s for a different sound. You want THUNDER from your vintage Ampeg SVT? Then this is your tube. You guys with 800 series Marshall's and mid to late 70's Mark II series Marshall's using 6550’s these are a drop in replacement, just re-bias and play! See the photo of two 800’s one with JJ E34L’s and one with JJ KT88’s in the tube substitution section. (Photo’s courtesy of long time friend Jim Songer.)  None of the pins are connected to the metal bases so there are no possibilities of shorts.
Eurotubes - JJ Electronic 6550
JJ Electronic 6550 Factory Data Sheet: 6550  Factory description: Gold plated control grid for improved fidelity. Special plate alloy to improve plate dissipation. Our observation: Everyone here at Eurotubes took a step back when we first auditioned the new JJ 6550! Most 6550's and especially new production tubes are pretty sterile sounding so our benchmark was to A/B the JJ 6550 against some of our NOS GE, RCA, Sylvania and Coke bottle Amperex 6550's. Most of the time JJ Electronic tubes will hold their own with NOS equivalents or even surpass them but in the case of the JJ 6550 these are hands down the best 6550 we have ever heard. They are very warm with a great clean tone and the breakup raw, crunchy and gritty. If you want an Angus - AC/DC type tone then these tubes really deliver! they are simply a lot of fun to play. The JJ 6550 will not make as much power as the JJ KT88 and the KT88 is thicker sounding, in fact some players feel it's too thick, so if you want a fatter sounding tube than a 6L6 that breaks up earlier than a KT88 then the JJ 6550 may be just right.
Eurotubes - JJ Electronic EZ81
JJ Electronic EZ81 Factory Data Sheet: EZ81  Factory description: Special plate alloy material and improved design for better performance, stability and life. Our observations: This is a great rectifier tube for the little 20 watt Marshall's or any other small guitar or Hifi amp that uses a 6CA4. The same great JJ quality that we are all used to.
Eurotubes - JJ Electronic 5Y3S
JJ Electronic 5Y3S Factory Data Sheet: 5Y3S   Factory description: Special plate alloy material and improved design for better performance, stability and life. Our observations: This tube is a real directly heated tube unlike it's russian and chinese counterparts which are stiffer because they have higher voltage output than 5Y3 spec. It's very dynamic and a great replacement for for any 5Y3.
Eurotubes - JJ Electronic GZ34
JJ Electronic GZ34S Factory Data Sheet: GZ34S Factory description: Special plate alloy material and improved design for better performance, stability and life. Our observations: This tube is as close as it gets the old Mullard GZ34 that we all know and love! In fact the plate construction looks to be almost identical to our large base Mullards with the straight edge plates. Bob’s been using these in all his old SUNN amps now for years with great results. They seem to know just when to give in to get that wonderful rectifier sag. We also use these in Mesa Dual and Triple Rectifier amps in place of the stock 5U4's to get a little less sag but to maintain that rectifier sound. A perfect tube to replace the chinese or sovtek 5AR4's that we have all grown to dislike so much... The JJ GZ34 will get  your Deluxe sounding like a vintage amp.
Eurotubes - JJ Electronic 5U4GB
 JJ Electronic 5U4GB Factory Data Sheet: 5U4GB   Factory description: Special plate alloy material and improved design for better performance, stability and life. Our observations: This is a great replacement for any 5U4. It has the a sound and feel that is as good as an RCA or a Sylvania. Just the right amount of sag at higher volumes! very dynamic.  
Eurotubes - JJ Electronic 2A3-40
JJ Electronic 2A3-40 Factory Data Sheet: 2A3-40  Factory description: Plate dissipation up to 40 watts gold plated control grid, heavy gauge glass and support rods with thicker alloy plate, ceramic base. Our observations: This tube is an absolute wonder. It's detail is even better than the 300B which we thought was impossible... Very warm and liquid sounding. We loaned a pair to David Bardes for a review he was doing on 2A3 amps for Vacuum Tube Valley magazine so he could compare them to the chinese 2A3's and after trying them they remained in the amps for the remainder of his review simply because there was no comparison, the JJ 2A3 was hands down a far superior tube. You can read a review of the JJ 2A3-40 here. 
Eurotubes - JJ Electronic 300B
JJ Electronic 300B Factory Data Sheet: 300B   Factory description: Plate dissipation up to 40 watts gold plated control grid, heavy gauge glass and support rods with thicker alloy plate, ceramic base. A directly heated tube with real magic performance. Our observations: Very detailed and smooth. Customer feed back on these tubes has been extremely positive. We have done a lot of A/B listening with the Sovtek and Svetlana 300B’s in our JJ 322 amp and the JJ’s are very up front and pure compared to them.
JJ Electronic EL34II Factory Data Sheet: EL34II  
Factory description: Gold plated control grid for improved fidelity. Special plate alloy and completely new anode for improved fidelity and performance. Our observation: The JJ EL34II prototypes came to us in September of 2014 for testing and we were all amazed that JJ could come up with yet another variant that has it's own sound and distinct place in the already heavily populated EL34 family! The EL34II's are fuller sounding than the standard EL34 but not as "in your face" and aggressive as the JJ E34L. If aggressive, tight and punchy is what you want the E34L is King. The EL34II is a perfect choice for players who love  a traditional EL34 sound but need to fill out the low mids and low end without losing any upper mid and high end crunch or definition. They are very warm and sweet sounding!
JJ Electronic 5881 Factory Data Sheet: 5881   Factory description: Special plate alloy material and gold plated control grid. Plate dissipation of 23 watts. Heavy gauge glass. Can replace any 6L6 in all applications. Our observations: ThisThe JJ 5881 prototypes came to us in September of 2014 for testing. We were very excited to see the traditional stubby bottle and completely new internal construction. We had spoken to JJ about the need for a really great 5881 that was built to be a lower power 6L6 just like the originals and they sure came thru on this one! One of the first amps we auditioned them in was a Blackface Twin. The very first words spoken to describe them was "Wow, its like Tweed in the bottle!" The power was noticeably down, the breakup was earlier and very smooth in transition. They have "jangle" for days! We LOVE these tubes! A wonderful option for any 6L6 amp.
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