Carvin Vintage 33 mod

The Carving Vintage 33 is a nice little amp and I enjoyed playing it until I heard a real vintage amp, my 1964 Blonde Bassman amp! Compared to the Bassman, the Vintage 33 was very “dry” and “sterile”, lacking warmth and “tone”. Yeah, you could turn on the reverb and get back some warmth, but turn off the reverb and watch out – it’s like sucking out the life of the amp. The ironic part is that the Vintage 33 sounds nothing like a real vintage amp, even though it “looks” like one.

I was determined to do “something” to get it to sound better. With help from AMPAGE (Rebel420, Carl Z, Paul C), I was able to make it sound a lot better.

These mods may not turn your Vintage 33 into a vintage Bassman, but your amp will growl and be alive and kicking! The normal channel will be lots more alive with more tone and feel and will break up a lot more when turned up. The distortion channel will have more of a vintage sound to it – less of the “solid state” tone it used to have.

All of these mods are reversable and no traces need to be cut.


Check and recheck the voltages using a multimeter until there is no appreciable voltage left. To do these mods you will have to remove the circuit board by taking out the chassis, removing the tubes, removing the knobs and nuts that hold the pots on and the channel switch. Once that’s done, you need to remove the screws holding on the PCB to the chassis.

Here are the mods I did (referencing the Carvin Schematic):
Replace the following 220K plate resistors with 100K

R3, R5,R10,R13

Replace R2 with a 2.7K resistor.

Replace C1 with a .68uF capacitor.

Replace C2 with a .02uF capacitor.

Take out C10 (.01uF) and replace with C2 (.0033uF).

Replace cathode resistor R12 (1K) with 2.7K.

Replace cathode bypass capacitor C15 (10uF) with .68uF cap.

Replace cathode bypass capacitor C7 (10uF) with 25uF cap.

Replace C30 (.001uF) with .047uF cap.

Replace Negative Feedback resistor R33 (220K) with 1M.

Replace R22 (3.9K) with 1.5K.

Remove C44.

Bonus: Get rid of those unbelievably CHEAP 10uF/50V electrolytic caps!!!!! Replace with Sprague or….. anything else that has quality!!!!!!! These electros are so cheap I wouldn’t even use them in my pedals!!!! THEY ARE HORRIBLE!!!!

Here is what I believe these mods do:

Replace the following 220K resistors with 100K

R3, R5,R10,R13

From Rebel420:
220k plate resistors make the overdrive a bit fizzy, and buzzy.. not its’ not a drastic difference at real low, or extremely high gain situations, but at moderate gain, there is a difference. Touch sensitivity is also a bit better with 100k

Replace C1 with a .68uF capacitor.

Replace C2 with a .02uF capacitor.

This combination gives the first stage more of the classic Marshal gain stage.

Replace C2 with a .02uF capacitor.

This “feeds” the rest of the stages with more bass/mids instead of rolling off the bass like the stock filter did.

Take out C10 (.01uF) and replace with C2 (.0033uF).

This rolls off the bass in the distortion channel only, to keep it more like the stock distortion channel.

Replace R12 (1K) with 2.7K.; Replace C15 (10uF) with .68uF cap.

My attempt to give the distortion channel more of the classic Marshall gain stage. The 2.7K/.68uF combo is used in Marshall amps.

Replace C7 (10uF) with 25uF cap.

Gives the normal channel more mids/bass – this is the value used in Fender amps.

Replace C30 (.001uF) with .047uF cap.

Thickens the tone by allowing more mids/bass into the phase inverter stage.

Replace R33 (220K) with 1M.

Reduces the NFB to the phase inverter stages. This mod really changes the way the amp “feels”. It loosens up that tight amp sound the Vintage 33 had. Makes it feel and sound more like a vintage amp.

Replace R22 (3.9K) with 1.5K.

Possibly brightens up the amp a little.

Remove C44.

Brightens up the amp – this cap rolled off some highs.

Rebias the amp until you get the “best” tone out of that little trimmer pot.

Like any other mod, you need to replace the components with other components with the same or larger voltage ratings. If you replace a 10uF capacitor with a 50 volt rating with a 25uF, make sure the 25uF capacitor can handle at least 50 volts.

Unfortunately, the Carvin we have has all of the “terrible” traits of cheap PCB amps; PCB mounted tube sockets!!!!!, non-hole-through PCB plating!!!!!, CHEAP components, PCB mounted pots etc… etc… You cannot fix all of these problems, but at least you know what to look for if something goes wrong. Check those solder joints on the tube sockets and pots.

These mods will not magically make your Carvin Vintage 33 into a real vintage amp, but if you close your eyes, you might be fooled! 🙂 Maybe you will be like me – play it more and more and more….

Here is an MP3 sample of the clean channel after the mods…

version info:

12/10/00 Changed first gain stage to 2.7K/.68uF Marshall Gain stage. No samples yet.

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