Bipolar amp ?

[Scotteboy]

Hi all in Marantz land,

I routinely recap Marantz gear and have a repair to do in the phono section (One channel out, good in all other inputs) on a Marantz 1060 that has been recapped.

In the phono section I pulled and checked the 2sc458's to start and they are extremely leaky. Next I will do the same on the 2sc1000's with ksc1845 replacing in all these positions. As usual all comments welcome.

This amp does however have all nichicon muse bipolar electrolytics where there were previously polar electrolytics in all board positions except power supply. The power supply has the traditional polar electrolytic caps.

My question is simply is this okay ? I am perplexed as a hobbyist and am thinking there must be some reason for the polarity or why take the extra time to design and build as such ? I understand a bipolar is two polar electrolytics "back to back" with positive and negative to each other in the center but any way what gives ?

Please redirect me if this has been covered.

 

[Guest159]

Polar electrolytic caps are used because they're usually the cheapest, most effective solution to the problem. It doesn't take special design efforts to accommodate them. Quite the opposite, in fact. Nonpolar caps are more complicated and have less desirable characteristics. Better audio gear that requires nonpolar caps usually use polypropylene caps.

 

[Pio1980]

It's a somewhat complicated situation, depending on average DC voltage differential on the elyticap whether polarized or non-polar. A high quality properly biased polarized elyticap is perfectly acceptable. As stated previously, a good plastic film cap is preferable in the audio path if the circuit and circumstances permit.

 

[Scotteboy]

So got the phono back to working one bad transistor besides the leaky 2sc458's. Recapped it with polar silmic II just to make sure and upgraded from 100 to 220UF on the main. Still feeling like a recap to full polars would be best but I guess old habits die hard !

 

[Guest159]

I've honestly never heard of anybody using nonpolar electrolytic caps throughout a circuit. I can't imagine any possible benefit, but I can certainly imagine some drawbacks. What makes you think nonpolars are superior in some way?

 

[Scotteboy]

Hi Reactive load, that is why I was asking, I had this come in for repair and was shocked to find it with all bipolar caps. I was trying to understand why this was done and did not agree with it but with no electrical engineering background , I wanted to check. I have recapped back to polar on the phono amp and will probably continue to replace the bipolar caps as it just doesn't make sense to me. I have done about 200 amps to date and never changed the design of the circuits radically, just bumps up in voltage capability and better quality components, replacements in pairs where subs were necessary etc. Thanks for reading and considering the issue, that's why I come here !