Thanks so much Stuart. It's been a while since I've seen any tutorials from you. Such a simple lesson can say so much. You are the master of valve amplifiers. 🔌
Great explanation video. The hardest thing I find about explaining ausio signals to people is that speakers have a polarity. So many people get hung up on the "Audio is an AC signal so it doesnt matter which way you wire the speakers" thing and forget that speakers have a polarity because you want the sound to punch OUT on the positive signals and pull IN on the negative signals. Its one of those cases where someone with a little bit of electrical knowledge thinks they know everything but cant quite grasp that wiring a speaker in reverse will sound awful. And, if they cant hear the difference for themselves, then they never believe me when I tell them "Its wired up wrong"
Ah I'm afraid you MIGHT be under a misconceptoin, not sure. I'll explain here in case anyone else reads it. The only reason speakers have a polarity marked is because you need to know when you are wiring more than one speaker to the output. You want them both (say) to go out and in at the same time. You don;t want one going out whilst th other is going in. You can definitely hear when speakers are out of phase like this. But for a single speaker, it doesn;t matter whuch way aound you wire it.
Hi Stuart,is a very good idea make this type of Tutorial explained on valves amps. It could be very interesting if you explain the Power Supply and Preamp section too, so togheter with this today,who want is have at home a necessary idea for maybe servicing his little amp or, if not; however he have a better idea on how the Amp works. In a simple way put togheter a little series of tutorial for servicing in example a generic amplifier in a 5 to 10w range it doesen't matter if is guitar or old vynile player with speaker incorporated ,radio. etc. etc. 👍 Roby
@stuartukguitarampguy5830 ..we have to liberate Canada next my friend hopefully sometime in 2026.. we really suffered for the last 3 years especially small business owners like myself.. I believe the US influences the rest of the world hopefully as things improve here it also will there.. one of the reasons I like your channel so much.. it's a metaphor, symbolic.. taking things apart to see how they work then putting things back together..
hi Stuart always enjoy your videos I would like to recommend The RSGB radio communication handbook the first three chapters of this book are an excellent foundation and cover valve theory you can obtain the books secondhand it doesn't matter how old it is I believe the confusion Traditional current flow and actual current flow goes back to Galvez he called the anode positive because it gains material in electric plating but it is important to know actual current flow is negative to positive
@ Yeah that's what I learnt as well but the holes move much slower and only really apply to semiconductor theory In a valve there are no holes because it is a vacuum
You described class B (not AB) since you implied each conducts only ½ of the time and that one takes over from the other at this mid/crossover point. In class AB (as with most all guitar amps with PP outputs like this), there is overlap near the mid-point where one turns off somewhat later/after the crossing and the other turned on somewhat earlier/before the crossing. Bias an AB output “too cold” and you reach class B. Bias even colder and you get “crossover” distortion where neither is conducting during the crossing moment. This difference may be a technicality, but this is a technical topic.
It's a way of tranferring maximum power with lower losses. The other method is Class A. It's lower distortion but you have to dump a fair bit of power to achieve it.
STUART, During Anti-Phase cycle the electron current is flowing from Plate/anode to cathode? That doesn't make sense at all because the plate anode doesn't have any electrons to flow in reverse in the opposite direction to the cathode. QUESTION#2 the screen grids are setting the Ultra-linear of what? The Ultra Linear is considered what. Some Ultra-linear voltage is set at 30% or 60% of the plate voltage. But What I'm confused about is what is considered Ultra linear, the Ultra Linear of what?
No, electrons always flow from cathode to anode, but by convention we say electric current flows from positive (anode) to cathode. I'm confised about your secod question. I don;t think I mentioned 'ultra linear'? Where did you get that from?
@stuartukguitarampguy5830 the screen resistors set the screen voltage as the ultra-linear point. Isn't that what the screen voltage is doing? Setting the ultra-linear point of the output tubes
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Thanks for taking the time to make this tutorial. Much appreciated!
Glad you enjoyed it.
Stuart,
I always enjoy the lessons with diagrams. Thanks for the info.
Thanks Michael.
Thanks so much Stuart. It's been a while since I've seen any tutorials from you. Such a simple lesson can say so much. You are the master of valve amplifiers. 🔌
Thanks very much.
Great explanation video.
The hardest thing I find about explaining ausio signals to people is that speakers have a polarity. So many people get hung up on the "Audio is an AC signal so it doesnt matter which way you wire the speakers" thing and forget that speakers have a polarity because you want the sound to punch OUT on the positive signals and pull IN on the negative signals.
Its one of those cases where someone with a little bit of electrical knowledge thinks they know everything but cant quite grasp that wiring a speaker in reverse will sound awful.
And, if they cant hear the difference for themselves, then they never believe me when I tell them "Its wired up wrong"
Ah I'm afraid you MIGHT be under a misconceptoin, not sure. I'll explain here in case anyone else reads it. The only reason speakers have a polarity marked is because you need to know when you are wiring more than one speaker to the output. You want them both (say) to go out and in at the same time. You don;t want one going out whilst th other is going in. You can definitely hear when speakers are out of phase like this. But for a single speaker, it doesn;t matter whuch way aound you wire it.
Good explanation of the output stage 👍
Thanks I'm pleased you enjoyed it.
Hey Stuart, it's great to see you making another great video!!!
Glad you enjoyed it!
Great info 🤘🏼👌🏼
Thanks Thomas
Thanks Stuart Big Help!!
Cheers Chris
Hi Stuart,is a very good idea make this type of Tutorial explained on valves amps.
It could be very interesting if you explain the Power Supply and Preamp section too,
so togheter with this today,who want is have at home a necessary idea for maybe servicing his little amp or, if not;
however he have a better idea on how the Amp works.
In a simple way put togheter a little
series of tutorial for servicing in example a generic amplifier in a 5 to 10w range it doesen't matter if is guitar or old vynile player with speaker incorporated ,radio. etc.
etc.
👍
Roby
hey Stuart.. you are probably watching us sort out the mess here in the states.. should be smooth sailing for a while..😁 🇺🇲
YEs I hope so. You can come and sort out our mess now!
@stuartukguitarampguy5830 ..we have to liberate Canada next my friend hopefully sometime in 2026.. we really suffered for the last 3 years especially small business owners like myself.. I believe the US influences the rest of the world hopefully as things improve here it also will there.. one of the reasons I like your channel so much.. it's a metaphor, symbolic.. taking things apart to see how they work then putting things back together..
Thanks man
Glad you liked it!
hi Stuart always enjoy your videos I would like to recommend The RSGB radio communication handbook the first three chapters of this book are an excellent foundation and cover valve theory you can obtain the books secondhand it doesn't matter how old it is
I believe the confusion Traditional current flow and actual current flow goes back to Galvez he called the anode positive because it gains material in electric plating
but it is important to know actual current flow is negative to positive
The way I learned it was that electrons flow one way and the +ve 'holes' left by them flow the other way!
@ Yeah that's what I learnt as well but the holes move much slower and only really apply to semiconductor theory In a valve there are no holes because it is a vacuum
You described class B (not AB) since you implied each conducts only ½ of the time and that one takes over from the other at this mid/crossover point. In class AB (as with most all guitar amps with PP outputs like this), there is overlap near the mid-point where one turns off somewhat later/after the crossing and the other turned on somewhat earlier/before the crossing. Bias an AB output “too cold” and you reach class B. Bias even colder and you get “crossover” distortion where neither is conducting during the crossing moment.
This difference may be a technicality, but this is a technical topic.
I didn;t want to over complicate this simple explanation.
Hey Stuart, why do we need a push pull configuration?
It's a way of tranferring maximum power with lower losses. The other method is Class A. It's lower distortion but you have to dump a fair bit of power to achieve it.
Hi Stuart, I have an old Hitachi amp with STK hybrid packs, are they ab class or something else, thanks
Not sure but it's highly likely to be class AB.
STUART, During Anti-Phase cycle the electron current is flowing from Plate/anode to cathode? That doesn't make sense at all because the plate anode doesn't have any electrons to flow in reverse in the opposite direction to the cathode. QUESTION#2 the screen grids are setting the Ultra-linear of what? The Ultra Linear is considered what. Some Ultra-linear voltage is set at 30% or 60% of the plate voltage. But What I'm confused about is what is considered Ultra linear, the Ultra Linear of what?
No, electrons always flow from cathode to anode, but by convention we say electric current flows from positive (anode) to cathode. I'm confised about your secod question. I don;t think I mentioned 'ultra linear'? Where did you get that from?
@stuartukguitarampguy5830 the screen resistors set the screen voltage as the ultra-linear point. Isn't that what the screen voltage is doing? Setting the ultra-linear point of the output tubes