I have several Quad 405-2 amplifier which I’ve done the usual recap on. I always go with the usual TL071 OPAmp. I have always followed DaDa electronics way of fitting a 100uF polarized capacitor instead of bipolar on C2. They fit the positive leg of the capacitor to ground. I myself usually use low leakage Nichicon UKL capacitors for this position. I recently just thought about if it’s is a good idea to use a Polarized cap instead of the bipolar that was fitted there originally. So, this morning I measured a couple of my 405s and saw roughly 0.2mV on both the negative and positive leg to ground, which seems fine. But what does the collective knowledge here say, should I replace the polarized with bipolar caps instead? Pic borrowed from DaDas 405 revision manual.
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My 405-1 comes with 100uf tantalum capacitors, which are polarized. As you mentioned, there is literally no voltage across it during the operation. It is fine to use polarized cap.
PS: I doubt TL071 performs better than LM301 in 405/405-2. LM301 is external compensated with C3 3.3p for the optimal bandwidth. TL071 is internal compensated for unity gain stability, which is sub optimal with voltage gain setup.
PS: I doubt TL071 performs better than LM301 in 405/405-2. LM301 is external compensated with C3 3.3p for the optimal bandwidth. TL071 is internal compensated for unity gain stability, which is sub optimal with voltage gain setup.
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Both those opamps are obsolete. You should use something more modern. And there is no way an LM301 is better than a TL071.
I use bipolar. There is an average of 0VDC on one pin, but it’s only an average. AC signals go both up and down.
I use bipolar. There is an average of 0VDC on one pin, but it’s only an average. AC signals go both up and down.