Some great mods can be performed as well with better SS rectifiers, coupling caps, and resistors. The little 202 doesnt have the most solid bass but it's a sweet little amp and a good used deal. It's actually fun to do an gives you a sense of involvement with the amp.
I would check the bias once a month although many wait longer. They are straightforward (follow the cable unhook recs). Bias the amp after it's warmed up and follow their directions. I do believe that biasing the amp is very easy besides the pain of getting to the adjustment. You can experiment here a bit but make sure you bias all four EL-34 the same. Going lower is less bias which can serve to perhaps make the amp slightly more controlled sounding with a loss of some sweetness. If you up it a bit, you get a slightly sweeter more lush presentation, but I dont recommend too much over 44/45. As I remember, the bias settings for the 202 are around 40mv. The original Jolida 202a has the adjustment on the bottom of the amp. Sorry for the dumb questions.we're tube newbies not yet in the know!īias adjustments are a bit of a pain for this Jolida unlike the 302 and 502 which have the trim pots on the top behind the power tubes. I know if my bro tube rolls, the new matched tubes should be equally rated as close as possible, right? And it's best not to mix and match from different manufacturers (one 12AT7 a Philips and the other a GE for instance, or should the rating for each be more important than who built them?). Would the insides of the tubes be burnt looking inside, and if so, are they best not to be used at all until such time as they can be replaced? I think the original owner may have set the bias too high, from what his e-mails indicated to my bro, but not entirely said in so many words.
If the bias is set too high, I assume the tube's lifespan can be greatly shortened. I think we've read that on the bottom of the chassis there are four set screws and what looks like a dip switch to attach the leads of the multimeter to.Ģ matched pairs (4) of 6CA7/E元4 power output We have our dad's ol' Fluke multimeter and a RadioShack digital multimeter to use.
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