OK... technical facts...
There are several differences between solid state and tube rectifiers (in the sort of simple circuits we're talking about here):
1. Tube rectifiers have a higher series resistance... which means that the power supply itself will generally have a higher source impedance (all else being equal).
(In engineering terms this is often referred to as "the power supply being softer" which is a non-technical way of saying that the regulation is poorer or weaker.)
(The high voltage drops more under relatively heavy loads.)
2. Tube rectifiers heat up slowly.
(So they impose a built-in "time delay" on how quickly the high voltage supply "comes up".)
3.
MOST tube rectifiers use a significant amount of current to heat their filaments... and most operate at 5V rather than 6V.
(So most amplifiers need a separate winding, or even a whole separate transformer, just to run the filament on the rectifier tube.)
(A typical 5AR4 uses about 9 watts
JUST TO HEAT ITS FILAMENT.)
This was a very popular rectifier tube back when tubes were current technology.
(And was considered to be a step-up from the more common 5U4.)
In "the old days", while there were slight variations in the specs for different brands, like most tubes these were considered to be "commodity items".
Nowadays, like everything else related to tubes, people insist that they hear differences, and huge premiums are asked for "premium brands".
(And, yes, they may actually sound a tiny bit different, or last longer, because of actual slight differences in specs between brands.)
A solid state rectifier is going to be more efficient and probably more reliable.
NOTE, however, that a simple solid state rectifier is
NOT "a drop in replacement".
(Note that there are replacements that include a solid state rectifier, but also include other components, specifically designed to mimic a rectifier tube.)
1.
A simple solid state rectifier will have a
MUCH lower impedance than a rectifier tube.
On the plus side this means that it will usually charge the filter capacitors faster and offer a higher high voltage output.
As a result you may actually get more output power.
HOWEVER this higher inrush current may stress some components...
And the higher voltage may exceed the ratings on other power supply components or your output tubes...
(In other words there are several things to consider before replacing a tube with a solid state rectifier.)
2.
A simple solid state rectifier has no warm-up time.
This means that, unless it includes another sort of time delay, your high voltage supply will rise to full output
INSTANTLY.
In the past there were some worries that it was bad for the output tubes for the high voltage to be applied before the filaments were fully warmed up.
(The fear was something called "cathode stripping"... and it is still disputed whether this is a real issue or not.)
HOWEVER, there is another voltage issue...
The power supply will "go fully on"
BEFORE the tubes it is powering warm up and start to draw plate current.
So, in the time before the tubes warm up, and before they are loading the power supply, the power supply voltage will "overshoot" (jump up).
In this time interval the power supply may rise high enough to exceed the maximum ratings on power supply capacitors and other components.
IN SOME CASES THIS ABSOLUTELY CAN CAUSE COMPONENTS TO FAIL - PREMATURELY OR CATASTROPHICALLY.
(And power supply caps tend to be difficult and expensive to replace.)
(This is why rectifier tube replacements may include additional inrush limiters or delay relays.)
3.
Since a solid state rectifier doesn't have a filament you no longer need all that power to heat the filament or cathode.
This means that, assuming you have a single transformer, you will be drawing 10-15 watts
LESS from the power transformer ...
So the transformer will run a lot cooler... and the whole amplifier will run cooler and last longer.
4.
Because the power supply impedance will be lower than it was with the tube
YOU CAN EXPECT THE AMPLIFIER TO SOUND DIFFERENT.
But... to address your final comment...
Yes, there are differences between brands, and between the different variations of the tube number (GA, GB, and so on).
And, yes, they
COULD result in different performance, or different life expectancy, or even slightly different sound.
But
MOST of the differences in prices are just based on "audiophile perceptions"...
(Back when these tubes were actually current technology the price difference between "cheap" and "premium" brands would have only been a few dollars at most.)
Also, finally, note that you
DO need to verify which tubes are interchangeable in specific amplifiers.
There are several of these rectifier tubes that have the same pinout but slightly different power or wiring requirements.
While they are generally thought of as "equivalent" some of them may be interchangeable in some amplifiers but not in others.
And, in some cases, using the wrong tube can damage your amplifier.
ALWAYS verify that they can be substituted in
YOUR amplifier before trying it.
Note specifically about your comment about "using double 5AR4's"...
A single 5AR4 draws a significant amount of current to heat its filament... (around 2 Amps at 5V)
And, since it's the only tube in the amp with a 5V filament, it is usually powered by its own separate 5V transformer winding.
(That winding also must be isolated from the others for other reasons...)
Therefore, if you add a second 5AR4, you will be doubling the requirements on this 5V winding...
This may require you to upgrade your current power transformer (or add a second separate transformer to run the 5V filaments).
(There are other changes needed as well... it is
NOT as simple as "dropping in an extra tube".)
I’ve been using these for some time but would like to try something different. Not that I don’t like the sound, BUT HA, HA, HA
I’d also like to try another rectifier.
Another Third Rail ask.
I've been really investigating the ST120 for use with Forte IV speakers.....
But one common beef? Recitifier. Some older version is claimed by many to do better......
Others say the amp is a lot for a SINGLE 5AR4 and recommend DOUBLE.......
Me? I wouldn't get caught up with that and would go WEBER Solid State and a time delay relay for the B+.......
At Tube Depot? 25$ to 400$.....That's a 16:1 spread. A LOT. And includes GZ34 and GZ37 types......I have NO idea......