It's been a while since I last updated this project. I've made two significant changes and changed my mind on an earlier change. I got compliments on my tone from a bandmate but there are still changes to be made.
I ordered new tubes from The Tube Store and while I was waiting for them I found some older tubes in my stock of parts I never seem to throw away. The one 12AX7 tube was never used but made in China. I didn't try it at first because I assumed the current tube was from China. The second tube I found was a General Electric I forgot about. I was excited about a big brand name tube so I pulled the 12AX7 out of the amp. Surprise! It was a Sovtek tube, Fender's brand of choice. I put the GE tube in and found out why I didn't use it before.
Tubes are mechanical devices. Their sound comes from physical plates. These plates can vibrate so precautions are taken during construction. When I cranked up the amp I got an awful audible rattle from the tube. The amp worked but the rattle made the tube useless. I'll keep the box.
So I decided to throw the Chinese tube in there. I noticed how quiet the amp was when I wasn't playing a note. But I also noticed lower gain. I was impressed though and will keep the tube. In the meantime I threw the Russian Sovtek back in the amp and then I noticed that the gain was lower too. I was starting to think another mod actually lowered the gain.
The tubes came in last Thursday and I was too busy to really evaluate them. The 12AX7 is made by JJ and they have a really good reputation. The 6V6 is from Tung-Sol and it was highly recommended. I was happy to notice that the hum levels lowered and the tone was brilliant. The Tung-Sol replaced a Chinese 6V6. I couldn't be happier with this power tube. The gain however was still down and so I did some research. Going back to the removal of the C3 capacitor, that is something I should not have done.
I spent the weekend researching modification choices and discovered a tone changing set of part replacements that I am going to do. It will replace C3 with this mod and should keep out harsh lows and provide more gain. Instead of adding a three-way switch I am doing a tone stack bypass switch instead. That should help fix the problem I'm having with single coil pickups. My Epiphone Les Paul's humbuckers are sweet sounding but the pickups on my Strat copy are weak. The tone stack bypass will boost the single coil pickup and hopefully give me a true "Champ" sound.
The greatest sound change came from removing the grill cloth from in front of the speaker! I read a forum where everyone was recommending it. I could see why after I took it off - it was a pice of microfiber cloth that looked like it should have been on upholstery. The cloth was too restricting and the treble boost was enormous after I took it off. I had some screen material so I doubled it up and placed it in front of the speaker. I'll have to take pictures.
I hope to have the complete mod finished next week. I will take some pictures. Speaker replacement is still up in the air but as of right now I doubt that I will replace it. The isolation box is up in the air since I've discovered an attenuator that might be easier to implement. My band played last Saturday and I was very pleased with my tone. This Fender Champion 600 reissue was a great choice for the project.
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