An amp building link

[M29]

Hello,

For those that that have an interest in building an amp here is a good link. http://www.diycustomamps.com/index.htm

Some good info on building a Champ, look for the Glass Audio article.

I am sorry if this has already been covered.

M29

[tot_Ou_tard]

Thanks M29.

That page has this link

http://www.diycustomamps.com/valvejunior.htm#vjrebuild

to the Voodoo Baby mod for the Valve Junior.

Vood, if you don't assert the copyright on your name you loose legal rights to it.

The knobs are labeled

Chant, Conjure, Trance, and Summon.

They messed up and didn't name a knob Mojo (& so did you Vood ).

The input jack is labeled pin.

They also say this on that page:

Unfortunately, in North America the power transformer in the Valve Junior is rated for 115 volts coming out of the wall socket. The voltage coming out of the wall in my home is about 124v. This increases the voltages in the Valve Junior. The result is that the EL84 tube will be over the maximum dissipation of 12W. One fix is to increase the value of R10 from 220 ohms to 1K ohms. Some of the newer Valve Juniors already have R10 as 1K ohms so it is a good idea to check.

[oldguy]

Unfortunately, in North America the power transformer in the Valve Junior is rated for 115 volts coming out of the wall socket. The voltage coming out of the wall in my home is about 124v. This increases the voltages in the Valve Junior. The result is that the EL84 tube will be over the maximum dissipation of 12W. One fix is to increase the value of R10 from 220 ohms to 1K ohms. Some of the newer Valve Juniors already have R10 as 1K ohms so it is a good idea to check.

Very true, and the 1K @ R10 needs to be at least 3 watts, 5w even. Also, reducing the EL84's dissipation by increasing R14 to 240-270ohm (1watt) is a good suggestion. This is where it's over the 12w limit, the R10 helps reduce B+ voltage.
I did these along w/ about a dozen other mods, plus a new Hammond output transformer, then replaced the stock coupling caps w/ Mallory 150's .022uF to try for a slightly more "Marshally" sound. It's a different animal now, and in a good way!