[Wind Chaser]

Input, rectifier, driver, output etc - what role do the various tubes play?  I have 6 tubes worth a thousand dollars surrounding a $28 rectifier, are rectifiers not as important or do they have less bearing on the sound?

Can a great tube sound less than stellar with other great tubes, i.e. is there such a thing as tube synergy?

[eclein]

I'd like to know also, good post!!

[Listens2tubes]

Most want old NOS rectifier tubes due to a lack of stable/lasting new production tubes. Next you will find some that hear differences from NOS rectifiers. Being I use a diode with a 30 sec delay in place of a hollow state $$$ antique. I can attest to the bass from my amps being faster, tighter and better articulated. No sag also has a nice effect. Makes for a less tubey sound. OK that part does kinda get me. The sag is due to the power tranny trying to keep up with the organ pedal and the orchestra while providing the voltage to said tube. Thus the rectifier can disrupt the sound in a most analog fashion.

L2T out....

[Steve]

Input, rectifier, driver, output etc - what role do the various tubes play?  I have 6 tubes worth a thousand dollars surrounding a $28 rectifier, are rectifiers not as important or do they have less bearing on the sound?

Can a great tube sound less than stellar with other great tubes, i.e. is there such a thing as tube synergy?

Alot depends upon the design used if the tubes will sound less than stellar when combined.

I love tubes, but tube rectifiers require smaller input capacitor filters without arcing, and if a choke is used, either as input or elsewhere in the filtering system, the power supply becomes more reactive. The last thing one wants is more reactance in the power supply, if we wish accurate fidelity. If a tube rectifier makes a sonic difference, then the choke, where ever it is located and with its high reactance, will make a sonic difference.

For instance, using a 40uf capacitor, the capacitive reactances at 20hz and 10khz are:

20hz = 199 ohms

10khz = .4 ohms

Let's check the inductive reactance of a 10 henry choke.

20hz = 1256 ohms reactance

10khz = 628,000 ohms reactance

Again, if a tube rectifier makes a sonic difference, then the choke, where ever it is located and with its high reactance, will make a sonic difference.

There are so many different designs, but I will attempt to give generalities.

Usually the input tube is designed for voltage/signal gain. The driver tube may have voltage/signal gain, or have a gain of less than one. It depends upon the application the output tube uses. If grid current is drawn over a portion of the audio/signal cycle, then the driver tube is either cathode out (for low impedance), or plate out and uses a stepdown interstage transformer to handle the grid current/crossover from high to low input impedance of the grid.

Of course the output tube and associated parts are used to "supply power" to the speaker/load.

Hope these crude examples help.

Cheers.

[Ericus Rex]

In my limited experience with tube-rectified amps, I've found that using tube rectification gives you that 'classic' tube sound; rolled off highs, sweet luscious mids and boomy, undefined bass.  The amps I've loved the most have all had SS rectification (converting variable AC into a voltage more like flatline DC, BTW).

Power tubes are self explanatory.  "Drivers" can be a number of things.  As Steve mentioned, there is always a tube that increases the signal in the input stage of an amp.  Other small signal tubes can do a number of things like:  increase the signal again in a second gain stage before power amplification, be used as a phase splitter in push-pull designs (one tube handles positive signal half, the other the negative signal half), or can be used in conjunction with the gain tube in circuits such as cathode followers or mu followers.  It all depends on the circuit.  Confused yet?

I'm trying to learn about these things too.  Books are invaluable here but so many are a tough read.