That was very educational. Thank you for the work you put into making these videos. It would have been interesting to hear that Champ compared to your personal Champ, Chris. But right now I am going to put into practice that simple and practical test to check my ground and fuses have been wired correctly.
Thanks Les. I am very happy that you appreciate the time it takes to make these videos. I wish I had compared the 2 Champs, and as another Commentor suggested, compared the EL34 to the 6V6 configurations.
Wickedly good sound. The Gretsch sounds epic through that Champ, great job! BTW I even check the phasing in the wall sockets..surprising how many are the wrong way round!
I've built several champs out of a Webster 205 reel to reel. They have a 5Y3 and a 6V6 but use 2 6AV6 and a 5879. Ijust use the 6AV6s as theyy are single triodes equivalent to half of a 12AX7 so 2 of them work as 1 12AX7. I use the cabinet and cut an 8 inch speaker in. The cabinet is made out o 3/8 ply. They sound great.
ive tried both ways of dropping the voltage- your way is much better than the usual 1k Cathode Bias resistor that you always hear about. I ended up withe the same setup as this- 3.9k Dropper and 560k cathode bias resistor. Sounds awesome!! Great video!!
Thank you for acknowledging the work that I and my colleagues like @uncledoug , @BradsGuitarGarage and @PsionicAudio put into our videos. It's a lot of work, especially the editing. I appreciate it, as I am sure they do, too. If you haven't found their excellent channels, I think you will find them jam packed with good info. Thak you for watching and joining the family.
A very good video. Champs and clones of them are nice simple little amps especially for a beginner to learn and compare and test many things. For example to try tone circuits or tone stack component values, putting EL84 instead of 6V6 using adapter, tweaking or removing NFB, adding a master volume, lowering B+, connecting output tube as a triode, trying different speakers etc.
@@theguitaramptech I was on the tools myself once upon a time, but I veered away from component level repairs back in the 90s, barring the odd favour and occasional essential maintenance on my own equipment. I went more into sound engineering, FOH and studio. I have a couple of old Selmers in the airing cupboard that are going to need attention, so I'll have to brush the cobwebs off that part of my braincell. Just the one cell ...
Slightly higher screen voltage can sound better in certain amps. If all the other readings are acceptable and the screens are a couple/few volts higher, I don’t worry about it. I’ve had amps sound less pleasing after lower the screens below plate voltage. It’s quite common to find this in single ended cathode biased amps. Yes,WGS sound fantastic in Blackpanel amps. The 10” Fat Jimmy ceramics work well in a Aa764. Adds a bit more lower mids to my ears. Punchier too.
Very interesting comment William. I am always happy to be proven wrong, an excellent way of learning. Here's my take on Screens: Nearly always, I will set to a client’s amp to be more gentle on the tubes and letting the screens run a little cooler helps ... and lets the screen do its job. My understanding is that the main job of the Screen-Grid is to become the PRIMARY ANODE in the tube, attracting the electrons from the Cathode and through the Control Grid. If the Plate is more positive than the Screen, as I suggest, the electrons go running towards the Screen and are then “handed on” to the Plate. If the Plate is less negative, there is not much incentive to move through the Screen. In TRIODE mode, tying the Screen to the Plate, effectively takes the Screen out of the picture and hence becomes a less efficient Triode instead of Pentode. But in some cases, such as this Champ, I go against my own sermon. I opted for a 560R Cathode resistor even though it was above my normal Class A upper limit of 110% even with a cooled Screen. Why? It simply sounded better. From memory 680R was the optimal value for dissipation but sound quality paid the price. Thank you for sharing your insightful thoughts, William.
You are SO right. I officially kick myself in the butt for not thinking of comparing the sounds of the 6V6 vs the EL34. Sadly, the Champ has gone back to Terry, the very happy owner. Thank you for brining my stupidity to my attention ... I think.
... not nearly as much as a speaker with 101 SPL. Save your money, your PT and your OT. Get the speaker. If you double the output power from 5 watts rms to 10 watts rms, you will only get a 3db of gain. But going from the speaker with SPL of 91 to 101 you get the equivalent of going from 5 watts rms to 40 watts rms. That is an 18db gain. The EL34 requires twice the heater current. Very hard on the tiny power transformer of the Champ. --- Thank you very much for the excellent presentation. I enjoyed it very much.
I ended up not using a screen grid resistor, but increased the first power supply dropping resistor to give me the double benefit of lowering the preamp voltages a little. I wouldn't change anything until you take voltage readings and do your calculations. Go through the steps I did in Part Two with your 5F2A as it is very similar to a silverface Champ (except for the tone controls). I would, however, recommend installing a 1K5 grid stopper, as I did.
Hi, very interesting work! Here are a few thoughts. Are you sure your schematic is for the Champ you have? The CBS Champ version around 1979-80 had 420V B+, while older ones had closer to 350V. Regarding your tests, that EL34 was not running at 24 watts, because you based the finding on cathode current, which includes screen current. Tube dissipation ratings are based on plate current. An EL34 in a cathode biased Class A design is probably sending 10ma out the screen. That means the plate has more like .057 ma, and is sitting around 86%, not 100%. Also, EL34s use twice the heater current of a 6V6. Your heater voltage will be lower, which may partly explain the lower power. Low heater voltage can also shorten the tube life and possibly overheat the little transformer. As far as plate voltages, I wouldn't worry. Fender regularly exceeded maximum voltages and dissipation ratings of power tubes. The 6V6s in particular can really take a beating; great tube. Consider using a JJ6V6S. Unlike an older 6V6 that has a 350v stated limit, the JJ can take 500V.
Thank you for those insights, John. Much appreciated. Yes, I usually allow an estimate for screen current to add about 8% to the combined Cathode current.
Hi Steve. The Weber 8A125, but I am a huge Weber fan and as such I would not be surprised if my hearing was biased. Having said that, I would be 100% happy with the WGS.
hi i drive my champ with a 6l6 ,i have 384v plate ,345 v on g2 and 470 ohm on cathode for 53ma dissipation 18watts ,i can pull 6.8 watts before clipping ,i could go up the plate to 450v maybe i could have a little more watts .No problem with a output transformer 100 ma but not less .It takes 35v voltage swing to drive 6l6 ;the same with el 34,you can use kt88 ,807 and many tubes in se ,but dont forget it modify negative feedback when you change tube
That’s cool! 18w sounds stone cold for a 6L6 in Class A. What rectifier are you using? Is it the same power transformer? I think there are other design considerations before you need worry about the 2K7 NFB resistor. But if it sounds good to you and nothing is cooking then I call that a win! Enjoy
hi i made a clone champ 5f1,i use hammond transformer 272 fx and i took a edcor 5k ,100ma for the output transformer ,and use diodes ultra fast for rectifier ,its sound good so its sure this is not original sound with 6v6 but its sound good for me ,my new project a spitfire matchless 15 watts push-pull class A ,its a very good amp .I took a 68k for the feedback on the 5f1 ,i took idea from Dave Hunter ,you can find his shematic on the net .regards @@theguitaramptech
Of course, once you move away from the traditional Champ design you can try anything. I can’t do that on a customer’s classic Fender, but this is exactly what I did with the TweedTone 12A for Artist Guitars. The 12A is too far away from a Champ to be called a modified clone…but it sounds fantastic. If you search for “TweedTone 12A” on my channel or TH-cam you will see what I mean. Have fun with your experiments!
@@kubockferre5532 Yes, I designed the TweedTone12A for Artist Guitars, but they own the schematic. I am sure you understand that I will always respect their rights to the schematic. Its a simple design which is is not too different to a Champ.
An excellent description, Bazza. I describe a flat white as having "silky smooth" milk compared to frothy. I used to think it was exclusively an Aussie-style coffee, but I actually had a very good, a properly sized, flat white in San Francisco.
That was very educational. Thank you for the work you put into making these videos. It would have been interesting to hear that Champ compared to your personal Champ, Chris. But right now I am going to put into practice that simple and practical test to check my ground and fuses have been wired correctly.
Thanks Les. I am very happy that you appreciate the time it takes to make these videos.
I wish I had compared the 2 Champs, and as another Commentor suggested, compared the EL34 to the 6V6 configurations.
Wickedly good sound. The Gretsch sounds epic through that Champ, great job! BTW I even check the phasing in the wall sockets..surprising how many are the wrong way round!
@@giulioluzzardi7632 yes, I have fallen in love with my Gretsch again. Good call for. Checking the power wiring.
I've built several champs out of a Webster 205 reel to reel. They have a 5Y3 and a 6V6 but use 2 6AV6 and a 5879. Ijust use the 6AV6s as theyy are single triodes equivalent to half of a 12AX7 so 2 of them work as 1 12AX7. I use the cabinet and cut an 8 inch speaker in. The cabinet is made out o 3/8 ply. They sound great.
Very cool! I'd love to hear it.
ive tried both ways of dropping the voltage- your way is much better than the usual 1k Cathode Bias resistor that you always hear about. I ended up withe the same setup as this- 3.9k Dropper and 560k cathode bias resistor. Sounds awesome!! Great video!!
Thank you! It makes me very happy to know that I have helped you!
Great info, as usual Chris. Hope to see more of your excellent videos soon!
Good vid again, and the right outcome with that 5U4 and EL34. Save the poor little power transformer!
Great minds think alike! Those little Champs are commanding more money these days and deserve to be treated with care.
Great vid with huge amounts of useful info!
Thank you for acknowledging the work that I and my colleagues like @uncledoug , @BradsGuitarGarage and @PsionicAudio put into our videos. It's a lot of work, especially the editing. I appreciate it, as I am sure they do, too. If you haven't found their excellent channels, I think you will find them jam packed with good info. Thak you for watching and joining the family.
@@theguitaramptech I have already subscribed to to all of you guys!
Legend!
A very good video. Champs and clones of them are nice simple little amps especially for a beginner to learn and compare and test many things. For example to try tone circuits or tone stack component values, putting EL84 instead of 6V6 using adapter, tweaking or removing NFB, adding a master volume, lowering B+, connecting output tube as a triode, trying different speakers etc.
Very true. Thank you for your insightful comment
Breaks up nicely! Modified the proper way. Excellent Chris!🎉
Thank you, Neville. I always appreciate your thoughtful comments.
A very interesting guided tour around the innards of The Champ.
Thank you 👍
I'm happy that you enjoyed it and have joined our family of amp-lovers.
@@theguitaramptech I was on the tools myself once upon a time, but I veered away from component level repairs back in the 90s, barring the odd favour and occasional essential maintenance on my own equipment.
I went more into sound engineering, FOH and studio.
I have a couple of old Selmers in the airing cupboard that are going to need attention, so I'll have to brush the cobwebs off that part of my braincell.
Just the one cell ...
You crack me up. I share your pain. The "Memory Department" of my brain is clinging onto its last remaining cell for grim life!!
Hee-hee; not "Fazed", ay?! Minha, mon cherie☝️. Sounds freakin' awesome! Luv ur work, Chris😉
Thank you so much!
Thanks Chris! Love to Harley!
Harley's going to get an extra sausage with his dinner tonight, thanks to you!
Another great video Chris. Really like your approach, very well explained and easy to understand.
Bravo sir 👏👏👏
That is what I strive for and its so good to be appreciated. Thank you so much.
Slightly higher screen voltage can sound better in certain amps. If all the other readings are acceptable and the screens are a couple/few volts higher, I don’t worry about it. I’ve had amps sound less pleasing after lower the screens below plate voltage. It’s quite common to find this in single ended cathode biased amps. Yes,WGS sound fantastic in Blackpanel amps. The 10” Fat Jimmy ceramics work well in a Aa764. Adds a bit more lower mids to my ears. Punchier too.
Very interesting comment William. I am always happy to be proven wrong, an excellent way of learning. Here's my take on Screens:
Nearly always, I will set to a client’s amp to be more gentle on the tubes and letting the screens run a little cooler helps ... and lets the screen do its job.
My understanding is that the main job of the Screen-Grid is to become the PRIMARY ANODE in the tube, attracting the electrons from the Cathode and through the Control Grid. If the Plate is more positive than the Screen, as I suggest, the electrons go running towards the Screen and are then “handed on” to the Plate. If the Plate is less negative, there is not much incentive to move through the Screen. In TRIODE mode, tying the Screen to the Plate, effectively takes the Screen out of the picture and hence becomes a less efficient Triode instead of Pentode.
But in some cases, such as this Champ, I go against my own sermon. I opted for a 560R Cathode resistor even though it was above my normal Class A upper limit of 110% even with a cooled Screen. Why? It simply sounded better. From memory 680R was the optimal value for dissipation but sound quality paid the price.
Thank you for sharing your insightful thoughts, William.
Excellent job. Thanks😊
Thank you again, Peter. I always appreciate your supportive comments.
Lovely work Chris! It would have been interesting to listen to that little beast with the el34 as well though.
You are SO right. I officially kick myself in the butt for not thinking of comparing the sounds of the 6V6 vs the EL34. Sadly, the Champ has gone back to Terry, the very happy owner. Thank you for brining my stupidity to my attention ... I think.
... not nearly as much as a speaker with 101 SPL. Save your money, your PT and your OT. Get the speaker. If you double the output power from 5 watts rms to 10 watts rms, you will only get a 3db of gain. But going from the speaker with SPL of 91 to 101 you get the equivalent of going from 5 watts rms to 40 watts rms. That is an 18db gain. The EL34 requires twice the heater current. Very hard on the tiny power transformer of the Champ. --- Thank you very much for the excellent presentation. I enjoyed it very much.
You are 100% right.
I agree on the double shot, my friend. But I'll take it black with a sugar.
A double shot espresso!! Yum. Sadly my cardiologist has strongly advised me to phase that liquid gold out of my life. Enjoy it
@@theguitaramptech A smart guy like you trusting a cardiologist - why? They are liars and murderers!!
Great vlog
Thank you. And how is your Moody GA40 going?
cool
Thanks mate!
You decided to put a 470 ohm screen resistor in for the 6v6? Should I do that for my home built tweed Princeton 5F2A?
I ended up not using a screen grid resistor, but increased the first power supply dropping resistor to give me the double benefit of lowering the preamp voltages a little. I wouldn't change anything until you take voltage readings and do your calculations. Go through the steps I did in Part Two with your 5F2A as it is very similar to a silverface Champ (except for the tone controls). I would, however, recommend installing a 1K5 grid stopper, as I did.
Hi, very interesting work! Here are a few thoughts. Are you sure your schematic is for the Champ you have? The CBS Champ version around 1979-80 had 420V B+, while older ones had closer to 350V. Regarding your tests, that EL34 was not running at 24 watts, because you based the finding on cathode current, which includes screen current. Tube dissipation ratings are based on plate current. An EL34 in a cathode biased Class A design is probably sending 10ma out the screen. That means the plate has more like .057 ma, and is sitting around 86%, not 100%. Also, EL34s use twice the heater current of a 6V6. Your heater voltage will be lower, which may partly explain the lower power. Low heater voltage can also shorten the tube life and possibly overheat the little transformer. As far as plate voltages, I wouldn't worry. Fender regularly exceeded maximum voltages and dissipation ratings of power tubes. The 6V6s in particular can really take a beating; great tube. Consider using a JJ6V6S. Unlike an older 6V6 that has a 350v stated limit, the JJ can take 500V.
Thank you for those insights, John. Much appreciated. Yes, I usually allow an estimate for screen current to add about 8% to the combined Cathode current.
Having listened to bother the WGS and the Weber, which one do you prefer on a Champ?
Hi Steve. The Weber 8A125, but I am a huge Weber fan and as such I would not be surprised if my hearing was biased. Having said that, I would be 100% happy with the WGS.
hi i drive my champ with a 6l6 ,i have 384v plate ,345 v on g2 and 470 ohm on cathode for 53ma dissipation 18watts ,i can pull 6.8 watts before clipping ,i could go up the plate to 450v maybe i could have a little more watts .No problem with a output transformer 100 ma but not less .It takes 35v voltage swing to drive 6l6 ;the same with el 34,you can use kt88 ,807 and many tubes in se ,but dont forget it modify negative feedback when you change tube
That’s cool! 18w sounds stone cold for a 6L6 in Class A. What rectifier are you using? Is it the same power transformer? I think there are other design considerations before you need worry about the 2K7 NFB resistor. But if it sounds good to you and nothing is cooking then I call that a win! Enjoy
hi i made a clone champ 5f1,i use hammond transformer 272 fx and i took a edcor 5k ,100ma for the output transformer ,and use diodes ultra fast for rectifier ,its sound good so its sure this is not original sound with 6v6 but its sound good for me ,my new project a spitfire matchless 15 watts push-pull class A ,its a very good amp .I took a 68k for the feedback on the 5f1 ,i took idea from Dave Hunter ,you can find his shematic on the net .regards
@@theguitaramptech
Of course, once you move away from the traditional Champ design you can try anything. I can’t do that on a customer’s classic Fender, but this is exactly what I did with the TweedTone 12A for Artist Guitars. The 12A is too far away from a Champ to be called a modified clone…but it sounds fantastic. If you search for “TweedTone 12A” on my channel or TH-cam you will see what I mean.
Have fun with your experiments!
hi.the 12a sound very well ,i would be curious to see the shematic ,i saw on the net but i did not found this.regards
@@theguitaramptech
@@kubockferre5532 Yes, I designed the TweedTone12A for Artist Guitars, but they own the schematic. I am sure you understand that I will always respect their rights to the schematic. Its a simple design which is is not too different to a Champ.
What is flat white with coffee, is it just a different term for milk?
A flat white is basically between a latte and a cappuccino. You could think of it as a cappuccino without the foam, therefore it is flat.
@@bazzathegreat3517 Appreciate it!
An excellent description, Bazza. I describe a flat white as having "silky smooth" milk compared to frothy. I used to think it was exclusively an Aussie-style coffee, but I actually had a very good, a properly sized, flat white in San Francisco.