This is what I read others saying and when I bought my pair I noticed it when I swapped them out on my DQ 10's . They both have the same boards in them but the 4430 has 3 boards 3 channel amp. Single power supply for all 3 . Just wondering if you could unplug one board not in use and if that may make the other 2 sound the same as the 4420 ? Same boards you would think would have the same output transistors but I will have to check that . Someone sent me the service manual when I fixed my 4420 and Maybe someone has both we could look and see if the Transistor are the same . Just thought this might be interesting quiz and might help a person's 4430 sound better in stereo mode .
B&K Reference 4420 Bias and DC offset adjustment
- Thread starter Txsaxkat
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As the title says I did work on this amp a while back Driver board caps and the metal can transistors one had fried . changed out the bridge rectifiers also . I had the info on setting bias and dc offset at the time but have misplaced it . Involved removing fuse or fuses and signal generator ? The pods on one side are hard to get to because the main caps are right up against them almost . So looks like you need to unscrew the heat sink and tilt it for access . I adjusted my Citation 16a and Sansui AU 717 after complete rebuilds on those . I trusted someone else to adjust this but not sure about that . So now that I did a couple looking to take next step . Learned to use plastic screwdriver or slip plastic tubing over the shank of a metal one . Thinking of installing muti turn side access trim pots . Anyway need some specs for the adjustments . I have been searching here but cant find the info that I seem to remember reading at one point .
About to re cap my 4430 and change the R11 resistors that get hot and raise them off the board like I did on the 4420 . They use the same driver board # but the 4430 has 3 and has less output transistors on them and is configured strange . This is why people notice a sound difference between the 4420 and 4430 . I have pics of the 4430 .
About to re cap my 4430 and change the R11 resistors that get hot and raise them off the board like I did on the 4420 . They use the same driver board # but the 4430 has 3 and has less output transistors on them and is configured strange . This is why people notice a sound difference between the 4420 and 4430 . I have pics of the 4430 .
Onlyanalog65
New Member
Hello, I was reading up on this thread and I have a ex4420 now. I have ordered all the parts for a recap. But I found a bad resistor in the R11 location. Can anyone tell me the value of this resistor and or what should I replace it with? I understand that the ex4420 and 4430 are the same but the ex4420 only has two chan. I have this spec sheet that has several amps listed above. But im not 100 percent sure if this correct? This spec sheet shows a 2.26k resistor for R11, is this correct? If not what should I install? Does anyone have a the ex4420 schematic?
Thank you.
Thank you.
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Onlyanalog65
New Member
If your looking for adjustment settings for the ex4420 bias. You remove the B- rail fuse. Clip on your mm and set the bias to 250ma, or .25a. Once you have your bias set then do your DC offset. Put your mm in DCmv and adjust for 0v. +/- 5mv. These amplifiers need to be set correctly so the relays click on and off. If your relays click off while adjusting dc offset you are to low. I hope this helps.