what does a Rectifier tube do?


I have an Air Tight Atm1 amp which uses 2 5ar4 Rectifier tubes. The manufacturer calls it Mullard Rectification. My question is what is Rectification? I ask becuase AirTight makes ATM3s which use the same tubes (EL34) but do not use 5ar4s for Rectification. Would that mean there is a different sound even though both amps use the same Output tube?
128x128justlisten
A rectifier turns alternating current and turns it into direct current. I don't know this from my own experience, but I've heard it said that the type of rectifier used does have an effect on the sound.
A rectifier tube (diode) changes alternating current into little lumps of direct current. See

www.electronicstheory.com/html/e101-39.htm

I remain,
To answer the question: A rectifier (or rectification) is anything that allows something to flow in one direction without hindrance, but not the other. Its possible for a loudspeaker's port to start acting as a rectifier: air doesn't flow out as easily as it does in, or vice versa. I believe its called a full-wave bridge rectifier that's used in solid-state to convert AC (alternating current) into DC (direct current).
I've no clue about Mullard rectification but I have two assumptions that the second diode tube either rectifies a phase inversed signal or the split-phase signal(where one phase is lagging bihind another by 1/2period making a twice as freequet "lumps" that are much easier to smooth up with capacitors that have proper time delay. Inverting phases as well as splitting phases can be done using a transformer.
thanks for the input so far.....the AirTight 1 (which I really think is the best tube amp Ive heard) uses 2 5ar4 rectifiers.....the AirTight 3 which is an amp Ive have always lusted after uses the same output tubes (el34) and input tubes, but does not use 5ar4 rectifiers. Each amp uses same transformers, point to point wiring and exact parts, Would the amps sound the same or in what way would the Atm1 differ sonically vs the Atm3 because of the lack of the rectification?