The Conrad Johnson Premiere is one great amp. I also like the Conrad Johnson MV50, an older amp but great none the less. By the way, glad to see you handled glass tubes with gloves, thank you for the video, I enjoyed it.
I had the MV55 before this, and it was great. I upgraded to the P11a due to getting Magnepans. The MV55 actually did OK with the 1.6s but the P11a has a little more gas.
@@mike.thomas I'm glad you are a conrad johnson guy. I always liked CJ, and the other brand I liked is Audio Research, but I tend to lean towards Conrad Johnson.
Tom Zielinski I like Acoustic Research, too. I probably could have gone either way, but I think I got the MV55 at a good price and after that my “matcher” tendencies took over 🤣
I appreciate your concern. Here's what Conrad-Johnson service has to say, in response to an email I sent them on the topic: "The KT120 tubes are electrically compatible with the PR11, enjoy." That's good enough for me.
I also now have a the same CJ 11a and I was also thinking of trying the kt120 but they require a higher voltage and so I'm going to call them to make sure...I would hate to fry the amp...because the original 6550 tubes pull much less voltage... also, if I were you i'd move the amp to the top shelf to prolong tube life with better heat dissipation and to not warp or crack the wooden shelf above your amp... if the tube swap worked, did you like the sound better than the original 6550c❓
@@briancampbell7712 Yes, as I said, I asked them and CJ said it was fine. I would not have run them, otherwise. But you can do your own check, too, for peace of mind.
I have the same CJ 11a...had mine on the bottom shelf like you and just rearanged my gear and put on top shelf...because the heat can disapate much better on top and I was concerned after feeling the next wooden shelf up that the heat could warp or crack the wood over time and extra heat not being good for the life of the tubes ...I suggest you do the same...move to top shelf... also did you check with CJ to see if the transformers could support the kt120 with them drawing a higher voltage from the transformers...? otherwise you could damage the amp...doesn't matter if you adjust the bias if the tranformers are not designed to operate the kt120
@@briancampbell7712 I obsessed over that, but never felt the heat was excessive, and it never did any damage to my rack. YMMV. Indeed I did ask CJ about using the KT120 in the Premier 11 and they said, essentially, “it’s fine … enjoy” (also covered elsewhere in comments here, if you’re interested). A lot has changed for me and my system, but I do miss the tubes from time to time.
@@mike.thomas thanks for the reply...why would you ever go back to SS after having this great CJ tube amp? ... I did the opposite and just put my SS Yamaha M2 amp up for sale after recently getting this CJ 11a...mine is the 11a version not 11... I really like my new CJ 11a Svetlana 6550c russian tubes...this amp to me is of high quality!
@@briancampbell7712 My circumstances and home have changed and I no longer have a dedicated listening room. I went with a Naim Uniti Star (look it up) along with a couple of Mu-So units for whole house audio. It’s like the total opposite of a tube-based separates system 😏. I had to let the Maggies go due to not having a proper room for them, so I ran KEF R3 speakers for a while. Then I found a beautiful 20+ year old set of Thiel CS1.5s which I love. Naim into the Thiels works very well. While the Uniti Star was in for service due to a bad display (about which I was very unhappy, and almost made a hate video), I bought a Muzishare tube integrated amp and used it with a BluOS streamer and fancy DAC setup, which was pretty and fun. I got the Thiels during this period, which was not necessarily the best match. Honestly I was glad to have the Naim back after I got the Thiels since the Naim has a bit more grunt. It’s also pretty elegant and is built like a brick shithouse (except for the display, apparently).
How does changing the tube type affect bass or does this unit not have any crossover adjustments? I can see where resistance from the tube can affect the voltage output on each channel. Ohms laws at work would dictate some kinda frequency control outside the tube as this would be expensive in my opinion. I noticed you love old record players. I found an old Yamaha gear drive for $5.00 at a goodwill store that had an olufsen cartridge. Man this thing stills works after 30 years and sounds great once the arm was rebalanced.
I couldn't tell you how the tube affects the bass. In my opinion, it's probably just audiophile silliness. However, there is the possibility that the tubes facilitate the amp controlling the speakers better and resulting in better bass. I do feel that it does sound a bit better/ballsier with these tubes. However, the mind is easily fooled, when $$$ are spent. In the end, I prefer to think of this sort of thing as pursuing my hobby and customizing my system just for the fun of it. Or if you like -- "audio jewelry".
Surprised you choosing CJ for magnepan. I thought maggies do well with lots of SS power. I wonder how like 300-600 watts of pass or coda power would do on the magnepans vs CJ.
Honestly, I think people overstate just how much power is needed. Of course, I don't listen to metal at deafening levels, either. I listen mainly to jazz and probably never get out of the mid 70s-80s dB in level. Everything has changed in my listening room (including the room). I now have a pair of old Thiel CS1.5s. Everybody says you need a world of power to drive Thiels, but I had them on a 45 watt Muzishare tube amp that satisfied (again, considering my listening style). I did finally put a Peachtree Nova150 on the case, but I'm damned if I hear a huge difference. There does seem to be that extra bit of "air" that comes from having way more than enough power though, I must admit. I just got my Naim Uniti Star back from service, so we'll see how that does. 80 watts of British power 🤷🏻.
@@Smood47 Yes, I moved from a house with dedicated listening/home theater room to a condo with no dedicated space. I decided to go “minimalist” and so I consigned everything in my setup. I ended up with a Naim Uniti Star (and a couple of Mu-sos), ripped all my CDs and ended up streaming everything in the end. I used KEF R3 and Polk LSiM 730 stand mounts until I got the Thiels in basically NOS condition recently. The Thiels are amazing and have a very small but attractive presence in the room. Not to mention the sound they produce. I’ve never heard more unique and arresting presentation other than with Maggies. The Star’s display broke and being an all-in-one that meant I had nothing for my main room. Thus the experimentation with the Muzishare and Peachtree amps. The Naim is back and now I have to decide whether to keep it or not.
I would have thought the Conrad Johnson 11a would be an end game amplufier❓I see a used one for sale but now not sure...please help me decide...I use vintage Tannoy Betkeley mkll speakers..would the CJ be a good match and better than my present dynaco st70 el34 tubes
@@briancampbell7712 No idea. I assume the Tannoys are ridiculously sensitive, so you won’t be pushing any amp hard. The P11 is indeed a beautiful and great sounding amp, but I honestly can’t say it will be better than your current setup, which you are probably barely pushing. Now I’m no electronic circuit design expert, but I feel like I’ve read here and there on the all-knowing internets 😉 that CJ didn’t do anything astounding with the P11’s design. That is, it’s pretty standard circuitry built to a high level of fit and finish. A lot of this game is just wish fulfillment, in my opinion. If you want one, get it, and don’t let anyone tell you whether it’s a good idea or not. Good luck!
@@briancampbell7712 I can’t really say for sure. I felt like maybe they had a bit more bass, but there was no way to blind test it. I left them in. It’s like having pinstripes or flames on your car ;-)
@@mike.thomas I just have the top portion of the cage removed but I think I'm going to remove the other half… Do you think the extra heat hitting the voltage regulators behind the tubes will do any harm ...?
@@briancampbell7712 I don’t think CJ would design a cage that would damage the tubes due to heat. Remember that old TVs, radios, and other electronics were partially enclosed with wood furniture for decades.
Pietro: I can't reply to your comment because of Google+ commenting (and how it sucks so bad). So, I thumbs-upped your comment. And, the answer is, yes, these tubes are running fine. Listened for a couple of hours last night. Sounds a bit different, I think. Needs more break-in before I know more.
I can reply to this comment :-). Turns out the amp works great with the new tubes. I think I hear a difference, but the mind is a funny thing. The tubes definitely *look* cooler! I still have the little CJ MV-55 (well, it seems "little" compared to the Premier 11 :-)), so I toy with the idea of switching back to that amp to see if I hear a difference in that case.
The MV55 comes to live with the original 6CA7 GE ( fat boy ) but they are rare and pricey,it's one of the best sounding Beam power tubes ever made, new production copes don't come close to the GE, the EL34 is a penthode often wrongly labeled as EL34/6CA7 .............6SN7 GTB RCA black plates have a creamy sound and good nos 12AX7/ECC83 are needed to drive the input voltage amplifier............
Make sure heater supply can handle the KT 120. 4x KT 120 need at least 9 amp heater current. 1.9 amp per tube. U don't want to over kill the power tran r u ?
8:10 just having nice looks is good enough for you? Damn... no way I would bother with a tube amp unless there was a substantial sonic gain over SS. Why bother with something that is much more pricey and annoying to maintain. But sonically there is definitely a gain.
man, unless an amp is designed to accept different types of tubes i wouldn't even dream of swapping different sizes. i know more about guitar amps and i know for a fact that an EL34 takes EL34, EL84 takes EL 84, etc. i would think over time you're gonna fry somethin. the other thing i find interesting with hifi tube amps vs guitar amp tube amps is that hi fi isn't coming close to getting to the real sound of the power tubes. in order to break up guitar amp power tubes you need to really crank the amp, but that of course develops distortion, which is good. in hifi, it's bad. so maybe what i'm saying is hifi tube amps are more gimmicky than anything, only because between EL34s, 6550s and KT120s, although they each have their own tonal characteristics, i don't think anyone comes close to really cooking them unless your amp is cranked. or i could be way off on this. i'd love to know if your amp survived this 'upgrade'
+TheNewGranada It has survived fine. If you look at the other comments you'll see another guy was horrified and made grave proclamations, even though I asked the makers of the amp, Conrad-Johnson, whether it was OK (and they said, "yep ... enjoy"). I tend to agree that tubes in hi-fi are a bit gimmicky, esp in hi-end amps like this one where the goal is accurate reproduction. Aside from that, tube amps supposedly always introduce just a bit of 2nd-order distortion, which sounds good in smal amounts (as opposed to "really cool" in large amounts, as in a guitar amp). So that apparently accounts for the "tube sound" in hi-fi ampliiers. To me, a big part of audio (and music) products is the emotional side. HI-fi guys can get just as emotional about their amps and turntables as guitar guys do about their amps, pickups, and "tone woods".
oh for sure. however, in guitar rigs you can HEAR differences, especially in that different power tubes produce different types of sounds. however again, you aren't reaching those tubes unless you either really crank it or use some sort of attenuator. in hifi, I think because guys shell out so much dough that they psychologically convince themselves they hear a difference. I mean, speaker cable lifts? so cable doesn't rest on the floor? that's a good one. but i'm glad that you are able to swap tubes like that. i'm just amazed that the amp accepts it and glad your gear didn't suffer any calamity :)
Attention , juste warning you to monitor your transformator , it should not overheat or maybe worse and burns out by the use of KT120 tubes !!! Filament current is higher for each KT120 ... the TOTAL current difference is the current consumed by each tube times four ! Temperature in use should not rise above 70°- max 80° .... It's good to experience and to upgrade ........ It's also good and sometimes better to be careful. I also notice by your comments and the way you bias the tubes that you lack experience and knowledge about tubes .........that is not a critic but a simple fact ,you are a user but you seem to think you know tubes as many enthousiast do . I read in the comments I am not the only one to warn you..............We all made mistakes . Normally you should apply HT only after the filaments warmed up for at least a minute ! Happy listening and have a nice day !
Frank Geeraerts Thank you for your kind and informative comment. You are right that I am not deeply experienced with electronics design, esp when it comes to tubes. More of an interested layperson. But it is for that reason that I follow Conrad-Johnson’s biasing instructions very carefully. It is also why I contacted C-J regarding installing these tubes, to which they replied “no problem - enjoy”. I will just hope that they are not trying to get my amp in for service by giving me bad advice :-). I listened for many hours after doing the swap, with no negative effects. Happy listening to you too!
My pleasure if i can be of any help to you ..........it was wise to consult CJ ! And written proof to cover you if something would have gone wrong . You have a good sounding amplifier and worthy to use good tubes in it ... If you want to do fine bias , after tubes are well run in ...........check the line voltage before biasing, it must be your reference and as close to the voltage printed on the label of your amplifier ......... You can use a Variac to correct and adjust it for the right voltage....they are not very expensive and very useful. Than your bias will be factory correct and minor wall line voltage fluctuations will adapt ........ Tubes respond slowly to bias variations...they need some time to settle to the new working conditions ...........do it slowly with minor corrections and wait .... A well balanced PP will extend and lower the bass range , with greater overal power before the output transformator saturates. Power up the high voltage after the filaments heated up will greatly extend their live .you can do it your self or ask a skilled technician to install a switch between the diodes and the HV outlets of the power transformer. And you can improve the tonal balance of your input tubes with tube dampers from Herbielabs , the only one i like because they do the job and they don't impair on the heat radiation ... PS . the best line voltage is the voltage witch heats the filaments of the tubes as close as possible to 6.3 V.............it can differ a little from the theoretic correct voltage and will expand also tube life as well as installing the correct electric characteristics of the tubes. Feel free to ask if you have any questions . Have fun and play good music. PS : 6CG7 GE .............a lot of up and go .........very dynamic , little bit hint like a military march . RCA............less slam but tonaly richer and colorful ....more like a denser lower midrange , good stressless music like a good concerthall experience , more substance to the human voice .... Same for the 5751...............difficult to find good ones . If you can find RCA triple mica black plates ..........NEW NOS !!!! You will tell me ;) It's like a kitchen , the proof of the pudding is in the eating . DO the Final bias correction after 40 minutes when having played music on your normal soundlevel .
@@frankgeeraerts6243 I'm a new owner of a CJ 11a...please help teach me how to check the line voltage on my amp...and how to set correct it if needed🙏😁
@@briancampbell7712 The most common way is to use a variac to correct the AC voltage IF necessary ! My first goal is to monitor the voltage on the filament , as close as possible to 6.3 V or 12,6V.( most common voltatges ) Changing tubes , assure that the bias currents are adjusted correctly .
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The Conrad Johnson Premiere is one great amp. I also like the Conrad Johnson MV50, an older amp but great none the less. By the way, glad to see you handled glass tubes with gloves, thank you for the video, I enjoyed it.
I had the MV55 before this, and it was great. I upgraded to the P11a due to getting Magnepans. The MV55 actually did OK with the 1.6s but the P11a has a little more gas.
@@mike.thomas I'm glad you are a conrad johnson guy. I always liked CJ, and the other brand I liked is Audio Research, but I tend to lean towards Conrad Johnson.
Tom Zielinski I like Acoustic Research, too. I probably could have gone either way, but I think I got the MV55 at a good price and after that my “matcher” tendencies took over 🤣
I appreciate your concern. Here's what Conrad-Johnson service has to say, in response to an email I sent them on the topic:
"The KT120 tubes are electrically compatible with the PR11, enjoy."
That's good enough for me.
I also now have a the same CJ 11a and I was also thinking of trying the kt120 but they require a higher voltage and so I'm going to call them to make sure...I would hate to fry the amp...because the original 6550 tubes pull much less voltage...
also, if I were you i'd move the amp to the top shelf to prolong tube life with better heat dissipation and to not warp or crack the wooden shelf above your amp...
if the tube swap worked, did you like the sound better than the original 6550c❓
@@briancampbell7712 Yes, as I said, I asked them and CJ said it was fine. I would not have run them, otherwise. But you can do your own check, too, for peace of mind.
I always biased mine (had 2 Premier 11a amps) right on the edge of light off/on... When playing music they'll flicker off/on too... Nice light show
I always love this amp , the best for
vocals
You have an engineers heart for design and function if I was to guess.
I am a software developer, so I do approach many things with a technical pragmatism ;-).
Very well done.
I have the same CJ 11a...had mine on the bottom shelf like you and just rearanged my gear and put on top shelf...because the heat can disapate much better on top and I was concerned after feeling the next wooden shelf up that the heat could warp or crack the wood over time and extra heat not being good for the life of the tubes ...I suggest you do the same...move to top shelf...
also did you check with CJ to see if the transformers could support the kt120 with them drawing a higher voltage from the transformers...? otherwise you could damage the amp...doesn't matter if you adjust the bias if the tranformers are not designed to operate the kt120
@@briancampbell7712 I obsessed over that, but never felt the heat was excessive, and it never did any damage to my rack. YMMV. Indeed I did ask CJ about using the KT120 in the Premier 11 and they said, essentially, “it’s fine … enjoy” (also covered elsewhere in comments here, if you’re interested).
A lot has changed for me and my system, but I do miss the tubes from time to time.
@@mike.thomas
thanks for the reply...why would you ever go back to SS after having this great CJ tube amp? ... I did the opposite and just put my SS Yamaha M2 amp up for sale after recently getting this CJ 11a...mine is the 11a version not 11...
I really like my new CJ 11a Svetlana 6550c russian tubes...this amp to me is of high quality!
@@briancampbell7712 My circumstances and home have changed and I no longer have a dedicated listening room. I went with a Naim Uniti Star (look it up) along with a couple of Mu-So units for whole house audio. It’s like the total opposite of a tube-based separates system 😏. I had to let the Maggies go due to not having a proper room for them, so I ran KEF R3 speakers for a while. Then I found a beautiful 20+ year old set of Thiel CS1.5s which I love. Naim into the Thiels works very well.
While the Uniti Star was in for service due to a bad display (about which I was very unhappy, and almost made a hate video), I bought a Muzishare tube integrated amp and used it with a BluOS streamer and fancy DAC setup, which was pretty and fun. I got the Thiels during this period, which was not necessarily the best match. Honestly I was glad to have the Naim back after I got the Thiels since the Naim has a bit more grunt. It’s also pretty elegant and is built like a brick shithouse (except for the display, apparently).
How does changing the tube type affect bass or does this unit not have any crossover adjustments?
I can see where resistance from the tube can affect the voltage output on each channel. Ohms laws at work would dictate some kinda frequency control outside the tube as this would be expensive in my opinion.
I noticed you love old record players. I found an old Yamaha gear drive for $5.00 at a goodwill store that had an olufsen cartridge. Man this thing stills works after 30 years and sounds great once the arm was rebalanced.
I couldn't tell you how the tube affects the bass. In my opinion, it's probably just audiophile silliness. However, there is the possibility that the tubes facilitate the amp controlling the speakers better and resulting in better bass.
I do feel that it does sound a bit better/ballsier with these tubes. However, the mind is easily fooled, when $$$ are spent.
In the end, I prefer to think of this sort of thing as pursuing my hobby and customizing my system just for the fun of it. Or if you like -- "audio jewelry".
Surprised you choosing CJ for magnepan. I thought maggies do well with lots of SS power. I wonder how like 300-600 watts of pass or coda power would do on the magnepans vs CJ.
Honestly, I think people overstate just how much power is needed. Of course, I don't listen to metal at deafening levels, either. I listen mainly to jazz and probably never get out of the mid 70s-80s dB in level. Everything has changed in my listening room (including the room). I now have a pair of old Thiel CS1.5s. Everybody says you need a world of power to drive Thiels, but I had them on a 45 watt Muzishare tube amp that satisfied (again, considering my listening style). I did finally put a Peachtree Nova150 on the case, but I'm damned if I hear a huge difference. There does seem to be that extra bit of "air" that comes from having way more than enough power though, I must admit.
I just got my Naim Uniti Star back from service, so we'll see how that does. 80 watts of British power 🤷🏻.
@@mike.thomas You sold the CJ ?
@@Smood47 Yes, I moved from a house with dedicated listening/home theater room to a condo with no dedicated space. I decided to go “minimalist” and so I consigned everything in my setup. I ended up with a Naim Uniti Star (and a couple of Mu-sos), ripped all my CDs and ended up streaming everything in the end. I used KEF R3 and Polk LSiM 730 stand mounts until I got the Thiels in basically NOS condition recently. The Thiels are amazing and have a very small but attractive presence in the room. Not to mention the sound they produce. I’ve never heard more unique and arresting presentation other than with Maggies.
The Star’s display broke and being an all-in-one that meant I had nothing for my main room. Thus the experimentation with the Muzishare and Peachtree amps. The Naim is back and now I have to decide whether to keep it or not.
I would have thought the Conrad Johnson 11a would be an end game amplufier❓I see a used one for sale but now not sure...please help me decide...I use vintage Tannoy Betkeley mkll speakers..would the CJ be a good match and better than my present dynaco st70 el34 tubes
@@briancampbell7712 No idea. I assume the Tannoys are ridiculously sensitive, so you won’t be pushing any amp hard. The P11 is indeed a beautiful and great sounding amp, but I honestly can’t say it will be better than your current setup, which you are probably barely pushing. Now I’m no electronic circuit design expert, but I feel like I’ve read here and there on the all-knowing internets 😉 that CJ didn’t do anything astounding with the P11’s design. That is, it’s pretty standard circuitry built to a high level of fit and finish. A lot of this game is just wish fulfillment, in my opinion. If you want one, get it, and don’t let anyone tell you whether it’s a good idea or not. Good luck!
Are the KT-120s still on the amp or did you revert back to the 6550s? Thanks for sharing.
Hi. I do still have the KT-120 tubes in.
Nice amp.
what preamp do you use with this? I was thinking of getting a conrad-johnson , premier 10 preamp
@@briancampbell7712 ruclips.net/video/0bApV569dEY/видео.htmlsi=qOmffEZECeeQPNgS
did you end up liking the kt120 better than the stock 6550 tubes❓
@@briancampbell7712 I can’t really say for sure. I felt like maybe they had a bit more bass, but there was no way to blind test it. I left them in. It’s like having pinstripes or flames on your car ;-)
@@mike.thomas
I just have the top portion of the cage removed but I think I'm going to remove the other half… Do you think the extra heat hitting the voltage regulators behind the tubes will do any harm ...?
@@briancampbell7712 I don’t think CJ would design a cage that would damage the tubes due to heat. Remember that old TVs, radios, and other electronics were partially enclosed with wood furniture for decades.
Pietro: I can't reply to your comment because of Google+ commenting (and how it sucks so bad). So, I thumbs-upped your comment. And, the answer is, yes, these tubes are running fine. Listened for a couple of hours last night. Sounds a bit different, I think. Needs more break-in before I know more.
I can reply to this comment :-).
Turns out the amp works great with the new tubes. I think I hear a difference, but the mind is a funny thing. The tubes definitely *look* cooler!
I still have the little CJ MV-55 (well, it seems "little" compared to the Premier 11 :-)), so I toy with the idea of switching back to that amp to see if I hear a difference in that case.
The MV55 comes to live with the original 6CA7 GE ( fat boy ) but they are rare and pricey,it's one of the best sounding Beam power tubes ever made, new production copes don't come close to the GE, the EL34 is a penthode often wrongly labeled as EL34/6CA7 .............6SN7 GTB RCA black plates have a creamy sound and good nos 12AX7/ECC83 are needed to drive the input voltage amplifier............
Make sure heater supply can handle the KT 120.
4x KT 120 need at least 9 amp heater current. 1.9 amp per tube. U don't want to over kill the power tran r u ?
+thuanlu1 I contacted Conrad-Johnson and they gave me a thumbs-up.
How do you do this on a MV-60?
8:10 just having nice looks is good enough for you? Damn... no way I would bother with a tube amp unless there was a substantial sonic gain over SS. Why bother with something that is much more pricey and annoying to maintain. But sonically there is definitely a gain.
I said a few things there, the key word of which is “fun”. YMMV.
@@mike.thomas You do you.
@@Smood47 Always have. Thanks.
@@mike.thomas Cool proud of you.
@@Smood47
😮please show more respect to the author of this video...
man, unless an amp is designed to accept different types of tubes i wouldn't even dream of swapping different sizes. i know more about guitar amps and i know for a fact that an EL34 takes EL34, EL84 takes EL 84, etc. i would think over time you're gonna fry somethin. the other thing i find interesting with hifi tube amps vs guitar amp tube amps is that hi fi isn't coming close to getting to the real sound of the power tubes. in order to break up guitar amp power tubes you need to really crank the amp, but that of course develops distortion, which is good. in hifi, it's bad. so maybe what i'm saying is hifi tube amps are more gimmicky than anything, only because between EL34s, 6550s and KT120s, although they each have their own tonal characteristics, i don't think anyone comes close to really cooking them unless your amp is cranked. or i could be way off on this. i'd love to know if your amp survived this 'upgrade'
+TheNewGranada It has survived fine. If you look at the other comments you'll see another guy was horrified and made grave proclamations, even though I asked the makers of the amp, Conrad-Johnson, whether it was OK (and they said, "yep ... enjoy").
I tend to agree that tubes in hi-fi are a bit gimmicky, esp in hi-end amps like this one where the goal is accurate reproduction. Aside from that, tube amps supposedly always introduce just a bit of 2nd-order distortion, which sounds good in smal amounts (as opposed to "really cool" in large amounts, as in a guitar amp). So that apparently accounts for the "tube sound" in hi-fi ampliiers.
To me, a big part of audio (and music) products is the emotional side. HI-fi guys can get just as emotional about their amps and turntables as guitar guys do about their amps, pickups, and "tone woods".
oh for sure. however, in guitar rigs you can HEAR differences, especially in that different power tubes produce different types of sounds. however again, you aren't reaching those tubes unless you either really crank it or use some sort of attenuator. in hifi, I think because guys shell out so much dough that they psychologically convince themselves they hear a difference. I mean, speaker cable lifts? so cable doesn't rest on the floor? that's a good one. but i'm glad that you are able to swap tubes like that. i'm just amazed that the amp accepts it and glad your gear didn't suffer any calamity :)
Attention , juste warning you to monitor your transformator , it should not overheat or maybe worse and burns out by the use of KT120 tubes !!!
Filament current is higher for each KT120 ... the TOTAL current difference is the current consumed by each tube times four !
Temperature in use should not rise above 70°- max 80° ....
It's good to experience and to upgrade ........ It's also good and sometimes better to be careful.
I also notice by your comments and the way you bias the tubes that you lack experience and knowledge about tubes .........that is not a critic but a simple fact ,you are a user but you seem to think you know tubes as many enthousiast do .
I read in the comments I am not the only one to warn you..............We all made mistakes .
Normally you should apply HT only after the filaments warmed up for at least a minute !
Happy listening and have a nice day !
Frank Geeraerts Thank you for your kind and informative comment. You are right that I am not deeply experienced with electronics design, esp when it comes to tubes. More of an interested layperson. But it is for that reason that I follow Conrad-Johnson’s biasing instructions very carefully. It is also why I contacted C-J regarding installing these tubes, to which they replied “no problem - enjoy”. I will just hope that they are not trying to get my amp in for service by giving me bad advice :-).
I listened for many hours after doing the swap, with no negative effects. Happy listening to you too!
My pleasure if i can be of any help to you ..........it was wise to consult CJ !
And written proof to cover you if something would have gone wrong .
You have a good sounding amplifier and worthy to use good tubes in it ...
If you want to do fine bias , after tubes are well run in ...........check the line voltage before biasing, it must be your reference and as close to the voltage printed on the label of your amplifier .........
You can use a Variac to correct and adjust it for the right voltage....they are not very expensive and very useful.
Than your bias will be factory correct and minor wall line voltage fluctuations will adapt ........
Tubes respond slowly to bias variations...they need some time to settle to the new working conditions ...........do it slowly with minor corrections and wait ....
A well balanced PP will extend and lower the bass range , with greater overal power before the output transformator saturates.
Power up the high voltage after the filaments heated up will greatly extend their live .you can do it your self or ask a skilled technician to install a switch between the diodes and the HV outlets of the power transformer.
And you can improve the tonal balance of your input tubes with tube dampers from Herbielabs , the only one i like because they do the job and they don't impair on the heat radiation ...
PS . the best line voltage is the voltage witch heats the filaments of the tubes as close as possible to 6.3 V.............it can differ a little from the theoretic correct voltage and will expand also tube life as well as installing the correct electric characteristics of the tubes.
Feel free to ask if you have any questions .
Have fun and play good music.
PS : 6CG7
GE .............a lot of up and go .........very dynamic , little bit hint like a military march .
RCA............less slam but tonaly richer and colorful ....more like a denser lower midrange , good stressless music like a good concerthall experience , more substance to the human voice ....
Same for the 5751...............difficult to find good ones . If you can find RCA triple mica black plates ..........NEW NOS !!!! You will tell me ;)
It's like a kitchen , the proof of the pudding is in the eating .
DO the Final bias correction after 40 minutes when having played music on your normal soundlevel .
@@frankgeeraerts6243
I'm a new owner of a CJ 11a...please help teach me how to check the line voltage on my amp...and how to set correct it if needed🙏😁
@@briancampbell7712 The most common way is to use a variac to correct the AC voltage IF necessary !
My first goal is to monitor the voltage on the filament , as close as possible to 6.3 V or 12,6V.( most common voltatges )
Changing tubes , assure that the bias currents are adjusted correctly .