Best "Upgrades" to Jolida 202a

Tried to reply last evening but I don't see it included in this thread. Contact JoLida about their factory upgrades. Had them done to my 502B. Price was very reasonable and after a break in period, the sound is very good. Sounds similar to the (voicing?) of the unmoded 502B but better...a bit more detail, better imaging a little more heft or presence in the mid range and possibly deeper bass as well as maybe a little louder at the same volume control setting. They replaced caps, resistors, and volume control.

I believe that the 202A is quite similar to the 502A/B amps - the former being EL34 based & the latter 6550/KT88 based.
I used to own a 502A on which I had several mods done. I found the original amp to be very dark & lacking bass clarity. The amp sounded like I was listening to it in a bathroom stall. LOL!
I had the bridge rectifier diodes, power supply caps replaced. Most of the el-cheapo resistors, coupling caps were upgraded to Kimber Kaps (IMHO this amp did not deserve Cardas coupling caps, which were my 1st choice at the start). The decoupling caps for the tubes were also upgraded to Panasonic TS series. The driver stage tube was given a constant current bias stage using solid-state devices. I had the balance pot removed. Upgraded the volume pot to a Noble which was much better (Again I did not think that this unit deserved anything better).
After all of this, the amp did open up quite a bit.
If memory serves me correctly there was a design flaw in the bias of the driver tubes - the voltage on the plate (or cathode) was too high OR there was too much AC on it. In my particular unit this manifested itself as the amp eating driver tubes (if I remember correctly it was a 12AT7 tube) like crazy.
Another thing I did not like was there was a fair amount of global negative feedback in the design. Plus, the whole amplification chain has huge amounts of gain - something like 36dB, if I remember correctly.
The other thing I did not like about my integrated was that it used pentode tubes in ultra-linear mode. It sure gave me bass heft/slam but it was missing that sweetness. In contrast, I used to own AES Sixpac power amps that also used (EL34) pentode tubes BUT in triode mode - what a difference for the (much) better.
I usually used this amp as an integrated but one day, just for the sake of it, I connected it to my tube preamp - Jolida on full volume & preamp controlling signal amplitude - it sounded simply superb! Beguiling would be correct word to use here.
Anyway, this hopefully gives you some info re. mods.

The Jolida 202 uses basically the same circuit as the 302/502 (much different transformers) so any upgrades that work in these amps will also work in the 202.

For a few critical upgrades, I recommend the following.

1) Remove the volume and selector switch. Using it as a power amp with a good preamp in front of it will transform the unit. You will have to install a voltage devider to reduce the input level. I would recommend -6dB to -10dB.

2) Coupling caps -- whatever you like

3) Diodes - get rid of the $.02 silicon pieces and go with a decent Ultra Fast - Soft recovery type.

4) Power Supply Caps - A good Pansonic with low ESR.

5) Critical resistors - Cathode units with 5 watt Mills, Grids with good carbon comp or even the 1 watt Dale CW series.

6) If you goo with the triode mode, be careful. Any problems and you will fry the output transformers.

As always, be very careful inside any electocal component. There are voltages in there that can cause some severe problems. Your amp can be replaced, you can't.