Lots of capacitor questions...

[EFK]

Currently I am learning quite a bit about tube amps by experimenting with and modifying a Gibson GA42RVT. I would liek to experiment with changing out some a number of capacitors and I was hoping that someone could give me a bit of an education as to what types of caps are in there now.

First photo: there are a number of these caps throughout the amp in the signal path. They all read 223K/400V. I think these are .022uF? What type of cap is this? Kind of look ceramic but larger and thicker.

2nd photo: these look like little red chiclets. They all read 472T/630V. Also in signal path. ???

3rd photo: I'm pretty positive these are caps too but they look like little blue plastic boxes. All read G104252537521/u1K400 V4 Are these 1K, 1 uF or ??? 400 volt? Can't figure these out.

4th: there are a bunch of these, some of them cathode bypass caps. They appear to be tiny electrolytics (correct? no?), all read Nichicon 22uF 25V. Do cathode bypass caps need to be this type of cap, or can I play with orange drops, sozos etc. ???

Are ANY of these caps considered good? Not good? So-so? I know its debatable as to whether different types of caps of same value are different but I have heard personally some interesting changes following cap jobs with so-called premium caps.

Also: all of the main filter caps in this amp are KQC, 100uf/400V radial "vent" (whatever that means), while some of the secondary electrolytics are Chang 22uf/450V radial. What would be considered some premium or 'best' caps of this type to use?

One thing I have learned is that the schematic Gibson sent me directly is very different in some ways as opposed to what is actually in the amp - obviously many values were changed and the circuit itself was revised either prior to or following release; I believe they sent me an earlier version schematic. This makes for some fun!

I realize there are many questions here but I will value ANY information or opinion. Thanks guys!

[Enzo]

Unless it says uf or something familiar like .022, you can usually assume the value is in picofarads. The numbers are read like a resistor color code. In fact some small caps have stripes and look like resistors. So 223 on a cap means 2-2-000pf, which is .022uf. The first photo is of film caps.

Your red chicklet is also a film cap. 472 means 4-7-00pf or .0047uf. Signal path? I would have no idea, it depends where it is in the circuit.

Yes the blue boxes are caps. Look at the circuit board underneath it where it says C22. The other caps also are makred as C something I bet.

In the USA, we still like to write things like 1.5k or 4.7uf. But in other parts of the world, and even here sometimes, that are using the units symbol in place of the decimal point. So 1.5k becomes 1k5, and 4.7uf becomes 4u7. That makes it a lot harder to overlook a little dot of a decimal point In the care of just ohms, as in 2.7 ohms or even .33 ohms, they use an R. So 2R7 and R33 result.

Your blue box says u1, which I interpret to mean .1uf, and yes 400v.

A lot of these questions could be answered by reading the schematic for that amp. Even when in typical Gibson style, the thing doesn;t quite match the amp.

Yes, the 22uf/25v caps are electrolytics - let me abreviate as ecaps. Note the stripe down the side with the negative sign indicating the negative end with an arrow. Polarity. ecaps pack a lot of capacitance into a small space. That is why they are used. otherwise for the most part capacitance is capacitance. Sure you can use a film cap instead. Go look up a 22uf film cap and check the size. Now decide if you want to try and stuff a half dozen of them into the amp.

Are ANY of these caps considered good? Not good? So-so? I know its debatable as to whether different types of caps of same value are different but I have heard personally some interesting changes following cap jobs with so-called premium caps.

DOn;t obsess over this. They work, they work fine. You may or may not hear marginal differences with different brand caps. Those differences may seem better to you or they may not.

You often hear wonderful improvement with a cap job using premium caps. On the other hand, the job is most times done because the old caps were tired in the first place. One has to wonder how much improvement there would be if you took a brand new amp with nice fresh caps and replaced THOSE with premium caps. I suspect that big difference would be a lot smaller.

Furthermore, often as not a cap job is accompanied by new tubes and maybe other upgrades. SO when I hear that some Fender amp got all new orange drops, a fresh set of tubes, a rewired and tweaked bias circuit, and maybe some silverface/blackface changes, and the guy then says "gee those orange drops sound great." Well I have to take that with a grain of salt.

[EFK]

That was extremely informative. Thank you! The biggest problem with the schematic they sent me is that even where some of the locations are changed and I figure out where things were moved around, values are in some cases different also. It's apparently been heavily revised - I'm not the only one who has noticed this as I remember a posting somewhere maybe a year ago wherein another owner of this amp also stated the schematic was nothing like what was actually in the amp!