[Polaris111688]

What effects does bypassing signal capacitors in the input stage of an amplifier have on the signal itself? I'm asking because I'm considering bypassing the 4.7uF Panasonic film caps on the input stage of the power amp I built with Obbligato film capacitors. Thanks ahead of time.

 

[tomb]

It's Black Magic.

Seriously, the effects are difficult to predict. Normally speaking, one might use smaller film caps to bypass electrolytics, but if a film cap is big enough (4.7uf probably is), it's possible that bypassing with a smaller film cap can improve certain aspects of the sound - better, more fluid mids, cleaner highs - that sort of thing.

However, the effect can be totally different with different caps. The changes may be more drastic depending on whether you're talking input vs. output, too. You may gain clarity in the highs but lose bass as a result. The best that can probably be said is to try it yourself - but don't spend a lot of money until you can see where it's going.

As always, Dsavitsk's excellent Notes On Output Coupling Capacitors is a great place to start. However, as noted earlier - things may act differently on the input.

 

[Jon L]

Quote:

Originally Posted by Polaris111688 /img/forum/go_quote.gif .I'm considering bypassing the 4.7uF Panasonic film caps on the input stage of the power amp I built with Obbligato film capacitors. Thanks ahead of time.

In your case, getting rid of the electrolytic will yield far more benefit than bypassing. Obbligato oil caps or films caps are cheap enough, I would personally just take out the electrolytic altogether.

 

[nikongod]

Quote:

Originally Posted by Jon L /img/forum/go_quote.gif In your case, getting rid of the electrolytic will yield far more benefit than bypassing. Obbligato oil caps or films caps are cheap enough, I would personally just take out the electrolytic altogether.

he is talking about bypassing a (actually medium quality) film with a better film.

there are trade-offs to be made. while bypassing can improve the sound of an inexpensive cap, it can also smear the sound. sort of pick you poision: a smeared sound or one that is not like the sound you want in the cap that otherwise wont fit the budget, case, etc. sometimes you do get the better sound of the smaller cap, without the smear, double bonus round then.

 

[04BluMach]

Quote:

Originally Posted by Polaris111688 /img/forum/go_quote.gif What effects does bypassing signal capacitors in the input stage of an amplifier have on the signal itself? I'm asking because I'm considering bypassing the 4.7uF Panasonic film caps on the input stage of the power amp I built with Obbligato film capacitors. Thanks ahead of time.

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif he is talking about bypassing a (actually medium quality) film with a better film. there are trade-offs to be made. while bypassing can improve the sound of an inexpensive cap, it can also smear the sound. sort of pick you poision: a smeared sound or one that is not like the sound you want in the cap that otherwise wont fit the budget, case, etc. sometimes you do get the better sound of the smaller cap, without the smear, double bonus round then.

nikonlgod has accurately captured some of the potential problems with bypassing caps when they are directly in the Signal Path. You can typically end up trial and error a number of combinations to reach the SQ that is pleasing to your ears.

You are using a Panasonic film which is really less than a medium quality Polypropylene film in the Signal Path. Instead of trying to bypass this cap, IMHO replace the Panasonic with a better Cap that does not need to be bypassed. It may not even cost much more than the bypass cap you would consider either.

An excellent cap review will help to provide a value/performance solution to achieve your SQ goals. The Obbligato, VitaQ PIOs, Auricaps, Clarity SA, Russian K42 PIO, etc are all worthy at fairly reasonable cost.

If you are willing to sprend more - consider the MultiCap RTX.

And watch the size of these Caps - they can get very large very fast....