I know you don't have a huge number of views and comments but believe me, it's coming to the right people. I really appreciate you making this as it has cleared up many questions for me. It's literally us or nothing, these amplifiers exist on the community that support them. Please keep doing what you're doing, I'd love you to get into the nitty gritty as you said and share your knowledge with us.
I have a couple comments if you don't mind. You probably know these already, I understand you're trying to keep things simple here. -The grid leak resistors' job is mainly to reference the grids, to ground in this case. Because the input impedance of the grids is very high, there's going to be very little voltage drop in the grid leak resistors, meaning the grids are going to be at close to 0V with no signal. -The cathode bypass caps actually form high pass filters, so they boost "high" frequencies. The thing is, if the bypass cap is large enough in capacitance, the cutoff frequency of the high pass filter may include bass frequencies as well. IOW, with a large bypass cap you're boosting the whole spectrum of frequencies, not just the lower end, while a small bypass cap will only boost the high end. Again, the larger the cap, the lower the frequency cutoff. -Push Pull power stages can be class A as well (not necessarilly always class AB), depending on the operating point, plate and screen voltages and OT primary impedance. If those are set so that both tubes conduct at all times, that's class A. If the tubes reach a point where one of them stops conducting when the input signal reaches a certain amplitud, that's class AB. -I believe another reason why they picked lower values for the filter and reservoir caps back then is because rectifier tubes have their limitations with regards to the current spikes they can withstand. When you switch on the amp with the caps discharged, theres a big current spike until those caps get to 300V or 400V or whatever. If the caps were much larger in capacity, it would take longer to charge them and the current spike may destroy the rectifier. The datasheet of that 5Y3GT specifies an input cap of 20uF. That's probably why Leo picked 16uF for the reservoir cap.
Wow, thank you for this comment. I was aware of a bit, but not all of the info you mentioned. That's the beauty of social media, different perspectives allow for better understanding. My filter theory has a long way to go and that makes a lot of sense what you mentioned about the cathode bypass cap in particular. Fascinating insight into the filter cap sizes too. Thank you again for the comment, this is great!
ahhh this was a cool comment to read. I ALWAYS find myself wondering just exactly WHY certain values were chosen. It's great to hear reasoning like this. cheers
What I dont get is with what kind of physics tubes can get dc power from same cable that our instrument signal is going on , I know I can put effort and find it online and I will , just sharing what I think most newbies like me will ask too Thx for the awesome video
Quite a bit oversimplified but, this would be good for someone who was thinking of getting into tube guitar amps and had no idea what anything was except that guitar amps have tubes. I won't break down everything and explain as that would be a page of info that no one would read anyway but rest assured there is more to it.
Yes, so your video would be like this. To the point and a perfect primer. We are dealing with a matrix of rc networks directing electron traffic. It can get so much more granular, but that's not the purpose of this video. A deeper dive would be great, so please get to it.
Hey I made a schematic based off of a class a amp I was wondering if you could help me out to see if I would get proper signal flow and right placement of the tone stack and getting as much gain as I can
Good question, the 10k is but the 22k isn't. The 10k drops the b+ voltage a little bit for the screen grid of the 6V6 power tube. The 22k drops the b+ voltage so it's in a suitable range for the 100k plate resistors for the 12AX7 preamp tube.
I know you don't have a huge number of views and comments but believe me, it's coming to the right people. I really appreciate you making this as it has cleared up many questions for me. It's literally us or nothing, these amplifiers exist on the community that support them. Please keep doing what you're doing, I'd love you to get into the nitty gritty as you said and share your knowledge with us.
Thank You :)
"Yeah!"
Really enjoyed this video. Brings back memories from HS electronics class ... a very long time ago.
Thank You!
I have a couple comments if you don't mind. You probably know these already, I understand you're trying to keep things simple here.
-The grid leak resistors' job is mainly to reference the grids, to ground in this case. Because the input impedance of the grids is very high, there's going to be very little voltage drop in the grid leak resistors, meaning the grids are going to be at close to 0V with no signal.
-The cathode bypass caps actually form high pass filters, so they boost "high" frequencies. The thing is, if the bypass cap is large enough in capacitance, the cutoff frequency of the high pass filter may include bass frequencies as well. IOW, with a large bypass cap you're boosting the whole spectrum of frequencies, not just the lower end, while a small bypass cap will only boost the high end. Again, the larger the cap, the lower the frequency cutoff.
-Push Pull power stages can be class A as well (not necessarilly always class AB), depending on the operating point, plate and screen voltages and OT primary impedance. If those are set so that both tubes conduct at all times, that's class A. If the tubes reach a point where one of them stops conducting when the input signal reaches a certain amplitud, that's class AB.
-I believe another reason why they picked lower values for the filter and reservoir caps back then is because rectifier tubes have their limitations with regards to the current spikes they can withstand. When you switch on the amp with the caps discharged, theres a big current spike until those caps get to 300V or 400V or whatever. If the caps were much larger in capacity, it would take longer to charge them and the current spike may destroy the rectifier. The datasheet of that 5Y3GT specifies an input cap of 20uF. That's probably why Leo picked 16uF for the reservoir cap.
Wow, thank you for this comment. I was aware of a bit, but not all of the info you mentioned. That's the beauty of social media, different perspectives allow for better understanding. My filter theory has a long way to go and that makes a lot of sense what you mentioned about the cathode bypass cap in particular. Fascinating insight into the filter cap sizes too. Thank you again for the comment, this is great!
ahhh this was a cool comment to read. I ALWAYS find myself wondering just exactly WHY certain values were chosen. It's great to hear reasoning like this. cheers
Dude this video has been sorely needed. Perfect for the greenhorns out there. Ty
Thank you
Excellent discussion. Thanks.
Glad you enjoyed it!
The youtube algo has been recomending some great small channels like yours lately. Great content, mate. Subbed.
Thank You!
I think you should have explained how the current through the tube gets amplified. If I was a beginner, I would find this very confusing.
Great suggestion!
What I dont get is with what kind of physics tubes can get dc power from same cable that our instrument signal is going on , I know I can put effort and find it online and I will , just sharing what I think most newbies like me will ask too
Thx for the awesome video
Quite a bit oversimplified but, this would be good for someone who was thinking of getting into tube guitar amps and had no idea what anything was except that guitar amps have tubes. I won't break down everything and explain as that would be a page of info that no one would read anyway but rest assured there is more to it.
Yes, so your video would be like this. To the point and a perfect primer. We are dealing with a matrix of rc networks directing electron traffic. It can get so much more granular, but that's not the purpose of this video. A deeper dive would be great, so please get to it.
Thank you, you’re exactly right!
Wow, Nardwuar knows all about tube amps. Who knew??
Keep on rockin' in the free world!
😂
nat
atbot GPT-3 (:|] 49:03 "... thank you. i drew schematics for sun amp out a community college. finally i can figure what i was drawing " [BEEP]
Hey I made a schematic based off of a class a amp I was wondering if you could help me out to see if I would get proper signal flow and right placement of the tone stack and getting as much gain as I can
Sure thing, I'll try my best
Can I reach you through a email you may have or anything?
Are the 10k and 22k the screen grid resistors?
Good question, the 10k is but the 22k isn't. The 10k drops the b+ voltage a little bit for the screen grid of the 6V6 power tube. The 22k drops the b+ voltage so it's in a suitable range for the 100k plate resistors for the 12AX7 preamp tube.