The mods were :-
- treble peaking circuit between low gain input and pre-amp gain dial replaced with a 68K resistor.(reduces treble)
- 10K resistor placed between the grounded tab of the mids pot and ground (more mids available)
- Bypassed V2a cathode resitor (820 ohm) with a 0.68 uF cap (more plexi-like mids)
- put a 0.0033 uF cap between the 4 ohm tap on the output selector and the negative feedback resistor (100K) (increases bass response)
- put a 330pF cap across the 68K input resistor of V1a (tweaks the mids a bit - in a nice way to my ear)
The Ceriatone 2204's come without a brite cap on the pre-amp gain pot. If there had been one, I would have removed it.
Just a quick update, for completeness of the thread.
I have now got an Ultimate Attenuator, which actually allows me to open the amp up and use it as it was intended.
With the mods I described above, it sounds good at very low volume but (as I suspected) very muddy when you get the master much above 1.
So now I have undone all the mods I described above, except for the mod replacing the treble-peaking circuit between the low gain input and the pre-amp gain pot with a 68K resistor.
So now, it sounds great at higher master volume settings. I generally run it with the master between 2 and 3. It sounds much thicker and generally better now than the clip in the first post.
One other beneficial thing I have done is to change the negative feedback circuit to a 47K off the 8ohm tap. THings are just a bit tighter than with 100K off the 4ohm tap. The amp has a tiny bit less gain like this but I prefer it.
Still loving the amp to bits though !!
