Question on "tube" amps....
- Thread starter soundhd
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spkrman57
wrongsideofthetracks
I'll try to explain
With a single ended tube amp(triode/tetrode/pentode), there is only 1 output device and the amp runs pure class "A", with 2 tubes, one is on while the other one is off. There are differenct classes of bias for operation (A,B,C,D,etc includeing G and H which are of the switching variety). But push-pull refers to more than one device sharing the aplification, usually on and off opposite of each other.
Hope this helped and did not confuse the issue
Cheers, Ron
With a single ended tube amp(triode/tetrode/pentode), there is only 1 output device and the amp runs pure class "A", with 2 tubes, one is on while the other one is off. There are differenct classes of bias for operation (A,B,C,D,etc includeing G and H which are of the switching variety). But push-pull refers to more than one device sharing the aplification, usually on and off opposite of each other.
Hope this helped and did not confuse the issue
Cheers, Ron
mhardy6647
Lunatic Member
Well that's on the right track, but not quite there. Stereo just means two channels of amplification, of course. Each channel might be single-ended or push-pull. The single ended topology can use any number of tubes in parallel (one per channel sounds best, though). In a single ended amp, the plate DC voltage goes right through the primary windings of the output transformer, and the output tube(s) amplify the whole (music) AC signal waveform, positive and negative voltages. The HV DC load on the output transformer is why one either needs big-butt, airgapped output transformers, or limits oneself to low power.
In a push-pull amp, there's a phase splitter ahead of the output tubes that separates the AC signal into its positive and negative components. These are amplified separately by two output tubes (or even numbers of paralleled tubes, as above) -- thus one tube 'pushes' and the other 'pulls'. The big advantage is this: the plates of the two output tubes are connected to the 'ends' of the primary winding in the output transformer and 'push and pull it with AC. There's no DC superimposed on the AC signal, so the transformer can be smaller and operate more efficiently... and in practice output power can be much higher.
Class A and Class B (and the hybrid Class AB) refer to the operating points of the output tubes. SE amps are USUALLY Class A (danged inefficient, but sounds great), but they don't have to be. PP amps are USUALLY Class AB (be they solid state or tube amps)... but there are a number of big, hotrunning, low-powered Class A SS and tube PP amps out there.
Next class, we'll talk about negative feedback...
In a push-pull amp, there's a phase splitter ahead of the output tubes that separates the AC signal into its positive and negative components. These are amplified separately by two output tubes (or even numbers of paralleled tubes, as above) -- thus one tube 'pushes' and the other 'pulls'. The big advantage is this: the plates of the two output tubes are connected to the 'ends' of the primary winding in the output transformer and 'push and pull it with AC. There's no DC superimposed on the AC signal, so the transformer can be smaller and operate more efficiently... and in practice output power can be much higher.
Class A and Class B (and the hybrid Class AB) refer to the operating points of the output tubes. SE amps are USUALLY Class A (danged inefficient, but sounds great), but they don't have to be. PP amps are USUALLY Class AB (be they solid state or tube amps)... but there are a number of big, hotrunning, low-powered Class A SS and tube PP amps out there.
Next class, we'll talk about negative feedback...
Thatch_Ear
Addicted Member
Besides the basic bones of how they work a typical PP amp will have up to 4 times the power of a single ended using the same tubes but at the cost of having to have a feedback circuit to control distortion. Single ended can often go without feedback making for a different sound that is a very good match to vocals and violins and other acoustical instruments.
For instance if you are into Female vocals with a small combo of acoustic intruments SE is one of the very best ways to go. But then you get into speaker sensitivities because of low power and other genies in the bottle that you have to free to get great performance out of your system.
For me the emotional impact of the music goes up and the goosepimple factor rises. I like it.
For instance if you are into Female vocals with a small combo of acoustic intruments SE is one of the very best ways to go. But then you get into speaker sensitivities because of low power and other genies in the bottle that you have to free to get great performance out of your system.
For me the emotional impact of the music goes up and the goosepimple factor rises. I like it.
