Can Someone Explain Rectifiers for me?

[screamndemon69]

i'm trying to learn about Mesa gear and i get the feeling from what i've read that rectifiers are a type of solid state circuitry coupled with tubes. can someone shed some light on this for me?

 

[hal9000]

i'm trying to learn about Mesa gear and i get the feeling from what i've read that rectifiers are a type of solid state circuitry coupled with tubes. can someone shed some light on this for me?

A rectifier is an electrical component used to limit current to a single direction in a wire. They can be tube or SS. In tube amps, the rectifiers are used to flip the negative half-cycle of the incoming AC wave so that creating DC from AC is easier. So, if you imagine a regular sine wave where the signal goes smoothly from 0 to the high max back through 0 to the low max, that's the 120 V 60 Hz AC coming into the amp. The rectifier(s) flips the 0 - low max portion so it's 0 - high max. Then, you add a few capacitors (and an inductor maybe) to smooth out the signal and all of a sudden you have an average high voltage that's pretty constant (let's say 450 V).

Most modern amplifiers have SS diode rectification which is very fast tracking and increases the voltage to the tubes. Rectos have two kinds of rectification, SS and tube because there is a different feel for each, and sometimes it's nice to have the option.

 

[ytse_jam]

hal9000 exposed the thing well. However, if you're a tube-or-nothing guy remember that solid-state rectification has got nothing to do with solid-state circuitry concerning the signal path! It's still a all-tube amp, rectification only gives the DC voltages.

 

[speedy mcfeely]

all that a rectifier does is convert AC to DC. the capacitors after the rectifier are for smoothing out the 3 phase AC that is now single phase DC. a filter cap takes up some of the gaps by slowly discharging and smoothing out the half wave form. a current limiting circuit is a circuit created using various components, and most of the time (unless vdc are required) don't need rectifcation. most will use a transformer to step up the voltage, or to step down the voltage. resistors will be used to control the current. Ohm's law:"the current of a circuit is inversly porportionate to the resistance of the circuit". E=I*R.

 

[screamndemon69]

thanks guys. i think i have a small idea of what you are telling me. i'm not an electronics guy by no means but you guys made sense in your explanations.
i appreciate knowing that it isn't like the hybrid amps that are tube and SS. i am a tube guy when it comes to live gigs but don't mind an SS amp for home or my teaching studio. i've not been a fan of rectifiers but to be fair i haven't spent alot of time with them either. from what i'm learning it sounds like you can get the best of both worlds in some of the Mesa models by choosing to use them or not. that's some serious versatility.
i've always been a Fender guy when it comes to amps but i'm becoming a Mesa convert the more i play them and learn about them. i've come to the realzation that i'm a 6L6 guy more than a Fender guy and not an EL34 lover. the more i learn and try out new amps that might change as well.
again, thanks.

 

[stokes]

screamndemon,you cant choose to use it or not.You can choose either solid state or tube in some Mesa's.The statement that you have "not been a fan of rectifiers",seems to infer you dont actually fully understand what has been explained.A tube amp has to have a rectifier,it is either solid state,or tube.A tube rectifier is a "vacuum tube diode",it basically has a plate and cathode to supply dc volts to power the tubes.A solid state rectifier is basically a solid state diode,it has a plate where ac volts enter and a cathode where dc volts exit,same as the tube,these are the basic description of these devises.The difference in performance is that the solid state has a faster reactance,so for the same ac in it will give you a higher dc out.A tube has a slower reactance and will give some degree of "sag" to the dc out,which will affect the "attack" and tone of the signal to varying degrees in different tube types.So you can be a "fan" of one or the other,but to say you are not a fan of rectifiers in general isnt an option.

 

[parsky1]

The Rectifier model of Mesa amps got its name because of it being the first amp to have both a tube and solid state rectifier. This allows the user to choose between the two depending on what sound he/she wants.

Every amp whether it be Fender, Marshall, Vox, etc all have Rectifiers in them. Most of them are solid state rectifiers anymore. Mesa brought back the tube rectifier because people wanted the old school sag like the very early guitar amps.

 

[zappaslaughter]

Being an old fender amp guy myself, I can realte to your point of reference. Old tube Fender amps sound much more "organic" than the solid state amps you see around today. The use of tubes seems to bring out more overtones and gives your voicings a more living breathing airy feel, especially in clean and semi distorted tones. The tube distortion is kinda Saggy and Brown, lacking the fluidity of some of the solid state amps I have tried.


My mesa says it can switch between silicon diodes and tube rectification. running 100W silicon diode on the heavy drive channel it's all clip and very defined. But the difference has seemed very subtle to me (might have to have the amp loud to really hear the difference)

I cannot get my LSC to sound like my Roland solid state, with that over compressed feel to it.

What old fender amps are you used to?
Was it solid state or tube (valve) driven?