My Latest Score - 1974 Silverface Vibro Champ

[Wittgenstein]

I recently picked this 74 Vibro Champ off Craigslist for $220. It worked but you could hear it needed new filter caps. The previous owner also had a 6L6 in place of the 6V6 which I did not like the sound of. I opted to just tear out of the old warped fiber board, leave the old cap can in place but just cut the leads out, and make a new turret board to house all the new capacitors. I was able to save all the old carbon composite resistors as they were all within tolerance.

The one modification that I did make was to split the third 22uf filter cap's ground to the power tube's cathode ground point. I was planing on running a twisted pair of heaters to further reduce hum, but it is so quiet the way it is, I doubt I will. I noticed that the intensity knob now works properly as before it sounded like it was at 6 or 7 as soon as you turned it to 1. Now it is a smooth transition. I love the sound of this little amp and it definitely has a different vibe than my 5f1 tweed champ.




Flicker High Res Files

[Leo_Gnardo]

Impressive work Mr Wittgenstein! I've found not much relief from hum in Champs by running filaments in the balanced mode BUT I've managed to drop hum to a "black background" by adding a pre-filter to the power supply. Just a 22 uF 500V cap and choke for a Twin. Studios love 'em. I call it the Hubert mod. Hum Free.

Since there's only one output tube, it does make a difference in tone. For @ 15 years I used a vibro Champ as my test bench amp. One day I tried ALL the 6V6's I had, new & used, and wound up with the one I started with. Eventually it failed and I went thru all the 6L6's too - this time a 6L6 was the choice. So it makes sense to use your ears & pick the best that way. Once all the tedious swapping & listening is done, you'll be convinced you have the best tube in there.

[Chuck H]

Hubert mod. Hum Free.

We need a "palm slap forehead" emoticon!