K4005b

Kits Audio Hi Fi Projects
1

Hi!
I recently bought two Velleman K4005B amplifier modules (kit). After components assemby, i’ve tested them and everything seemed to be fine.
Each of them is configured for bridge operation. The problem is when i use them simultaneously (left and right signal cable attached to cd player), a terrible hum (50 Hz) appears. The power supply (500VA, 80.000 uF) is intended to be in common use of amplifiers.

Hum does not disappear until i disconnect one amplifier module from player, otherwise everything work great (mono application). I’ve already tried using other sound source.

Can anybody advise me what should i do?

2

Check you wiring, you’ve made hum loop somewhere (ground wire loop).

3

tnx, i’ll try!

4

I have one more question. Can i connect 4 ohm speaker on this amplifier if it is in mono-bridged power?

5

No. In bridge mode unit requires a minimum impedance of 8 ohms (see manual).

6

I saw that in manual but is there any option to raplace tranzistors for example?

7

NO, Only TIP 142 and 147.