EAR 834p clone built in 2021 (Zhili Audio board)

Power supply 230V (Australia)

What to change (my thoughts).

I. You can remove the power supply PCB section from the main amp, (remember to wire up the b+ to Both channels when running the b+ power leads to the main board). However, I used a toroidal transformer with a shield in the same chassis, and found that this was not necessary as it ran as quiet as a church mouse. However, I've heard that some people have experienced hum issues.

2. As standard, the thing had too much gain, so I used some vintage NEC 12AT7s in the first two stages. I had pulled these from an old Akai tape deck that I restored but found that the tubes were still very good. This cut the gain (& may have helped with the hum), but I retained a Genelex 12AX7 as the final valve, as the Eq stage would require it I think for RIAA reasons.

3. Bridge the channel's Left & Right (B+ Grounds) together at the input end of the board. They are joined at the power in end, but joining them at the other end as well may help with reducing hum if you experience any.

4. Turntable earth point. Don't connect it to the intended ground point on the board. Instead, connect to one of the input ground points.

5. Change the 330pf caps in the bias stage (only ones on board) for 660pf caps, helps the bass.

6. Three caps on the power board are marked as 4,700uf, but my kit supplied 2,200uF. I used these as 4,700uF pushed up the heater voltage too much. You may find the heater still running a bit too high & may need to add a 1 ohm (3W) resistor in the output from the power board. You can tag it onto the two .25 ohm resisters in series on the board feeding the 6.3-volt line.

7. There is a single 10uF on the power board. They supplied a 250v one which is a bit too close to the max operating voltage. The board states 350v, so it's best to upgrade.

8. Replace the supplied 1uF, 0.15uF & .015uF cap's for better quality, two of each. I used some nice Russian PIOs, Mundorfs, and good-quality orange drops.

9. No need for any shielding between the power supply section & the main board, as long as you're using a Toroidal transformer & position it with common sense and add a screen. I don't even know if the screen is necessary but the Ali seller threw it in with the transformer. Although the toroidal transformer and case were not included in my kit, I asked the supplier to find them for me, which he did, and included them along with some other non-related parts I was looking for. So, never underestimate what these guys on Ali can do, even if they don't stock what you want. I had bought stuff before from this seller and found him to be very helpful.

After these few mild changes, the unit worked very well indeed with NO HUM. Once the tubes had about 30-40 hours on them it really came on song.