Hey Guys,
Well today was amp mod day, before Fritz even arrived this morning I had 2 fellow Forum guys drop off their amps for mods. Another Champ and an Epi Valve Jnr, ah the smell of summer time mods 8)
When Fritz arrived and we got to work on his little Cub 8.
As you can see from the pics it is pretty typical Chinese assembly/parts, first time I've come across a valve amp using SMD resistors (which I'm not happy about), but it does allow them to get the whole amp onto that SMALL PCB and the contruction is fairly solid, bar the ridiculously small signal traces.
First thing to address was to see if we could lower the hum a bit. As noted the amp suffers from a couple different hums/buzzes, part of which comes from the AC heaters. This was a fairly quick fix and a turn or 2 on the internal trimpot and we found the sweetspot. The indicator lamp as I shared is not implemented that well, any change in AC voltage can mean it turns on/off... an AC lamp will be a better bet powered off the heaters and it turned itself on and off at will during our tests.
Here are some before and after clips RE the hum:
Stock Cub 8 Hum
Modded Cub 8 Hum
Following the hum mod we decided to try a couple 'quick' mods/changes.
First up I recorded a little piece of music with chords and some picking into my DAW and then used a Reamp Box to send the same signal back to the amp, it is the same performance each time, with the same mic/placement and gain settings, so any chance you hear is a sum of the mods/tweaks. Signal was via my PRS SE ONE witha single P90, DI'd into and API 312 Mic Pre into Pro Tools.
The stock amp has Ruby Tubes. Ruby source tubes from all over and rebrand them, infact Mesa use Ruby, so you know they have undergone some form of QC outside of the factories they come from.
I wasn't that surprised to notice the difference between them and the JJ's were not night and day, but rather more minute, coming in the way of being a little more defined with the JJ's, the attack was cleaner/clearer, but the stock Ruby's were not bad, WAY BETTER than the cheap no name Chinese ones in say the Fender Champion 600.
So after swapping out the tubes we decided to sub out the Super 8 Celestion speaker with a Jensen C8R, boy did THAT make a difference! The Celestion is muddy and indistinct, the Jensen is alot tighter and brighter with more note definition/clarity and that was fresh out the box, it will smooth out a bit as it is broken in.
In the end Fritz left with the amp with a bit of hum reduction, a new set of valves and speaker, and not too much money spent - not bad considering the cost of the amp to start with and a VERY different amp from stock.
I've uploaded a couple clips and you can downloaded them below, in all cases the Tone was set at 12 o'clock and the HALF gain at 5, the FULL gain at 10 on the dials.
Stock Cub 8 - Half Gain
Modded Cub 8 - Half Gain with Jensen and JJ's
Stock Cub 8 - Full Gain
Modded Cub 8 - Full Gain with Jensen and JJ's
Cheers
Matt
