Vox AC30
Vox AC30/6 TB from 1993, so an early Korg era model. It was sounding distorted on all channels when I bought it. Replacing the output tubes did the trick. It came with a quartet of old RFC/Mullard/Philips tubes from the 1960's. In this case these old tubes didn't add any mojo, they only made the amp sound worse. A former owner had an extra preamp module installed on the amp. This was well done, looks tidy and clean but I might remove it in the future, personally I don't need an extra channel, this amp already has three channels. Amp has had a recap, partly Nichicon, partly Samwha. I'll probably redo the Samwha ones with better quality counterparts. The seller swapped the Celestion Greenbacks with Celestion Blue Alnicos so basically this is an AC30/6 TBX.
To Do
- The amp hums, hopefully this can be resolved with some lead dressing or by replacing the preamp tubes.
- Replace Samwha capacitors with Nichicon or Panasonic equivalents.
- Remove extra preamp/channel.
- Adjust intensity vibrato/tremolo, it now sounds too tame.
- Replace ceramics in audio path with film or mica equivalents.
Extra preamp module with filter rotary switch. Got to figure out what this box is actually doing. It's inserted just before the phase inverter.
Part of the PCB, check the revision number, this PCB really is the very first iteration, all schematics I could find have a revision designation of AC30-60-02. RV1 is the trimmer to adjust the depth/intensity of the tremolo/vibrato channel.
Verdict
This amp blows your socks off! It's punchy, accentuates the woody tone of my ES-335, eats my Mostortions and is just incredibly loud. The brilliant channel is amazing and has way more body and character than the clean channel of the Kool amp I've used for years. When rehearsing with the band hum is not an issue so I'll leave it at that.