What to replace tantalum caps with (Korean Studer 169 clone)

[substitute]

I'm gearing up to recap a korean DSE console, it's for the most part a clone of a Studer 169.  The channels are lousy with tantalum caps, they should be replaced with electrolytics right?  I remember coming across something stating that if they are in the audio path replace them.  If not (which I gather means filtering DC) don't worry about them.  The master channels are identical to the studer schematics, but the mic/line channels have some differences, enough so that I can't use the studer schems to trace what's doing what on the boards.  Should I just replace all the tants with electrolytics and be done with it?

 

[Kingston]

Firstly, why are you recapping? Is something broken? Tantalum caps don't dry up like electrolytics and don't need recap as a standard maintenance procedure. Some ancient ones might fail short and that is a valid reason for recapping.

Secondly, "coming across something" is a pretty lousy excuse for recapping if you don't even remember the details. There is nothing wrong with tantalum caps and they should sound great in general. The only thing you should be worried about is if they are ancient and about to fail short. Modern tantalums should not do this.

 

[substitute]

The console is pretty noisy, I'd like to quiet it down.  If I pull all the faders down it get's significantly more quiet, as I pull up the faders one by one the noise level builds up. 

The DSE consoles were made in the '80s, which isn't ancient, but replacing electrolytics after 20-30 years seems like standard maintenance.  I didn't know tantalums don't dry out. 

 

[Kingston]

The noise certainly isn't coming from those caps. It wouldn't even if they were electrolytics. Lowering the noise floor will be a significantly more difficult procedure and would mean changes in the design itself. But I can't say much without seeing schematics. As a rule of thumb one would start by improving (usually completely rebuilding/redesigning) the PSU.

 

[nielsk]

It's the tants connected to power that you may want to replace with electrolytics, tants often fail dead short which is a bad thing in this application. On an older device I would change all of these as it can prevent catastrophic failures.
In certain audio path applications tants can be superior, an electro will do in a pinch but may be an inferior replacement. No need to change any that are working properly, and as Kingston noted, you must consider the circuit design.
A more thorough description of the noise would help as well (hum, buzz, hiss, and so on...)

 

[substitute]

Here's the original inspiration for the recap
http://www.groupdiy.com/index.php?topic=38169.0

The real studers have many more electrolytics where the DSE has tants instead.  After more thought, 13 of the tants are 100uf/6v, since the power supply is +/- 15 it seems likely that they'd be part of the audio path.

I'll do a detailed comparison of the studer power supply schematic and the built in power supply that I have.  At first glance they look the same.  The studer manual specs it at +/- 15v 500 ma.  So if redesigning that is in order it shouldn't be to hard.

Also, the noise that builds up is definitely a hiss. 

 

[mjrippe]

From that original thread:

"I/o Module Caps list is:

100uf/25v x8
220uf/25v x5
47uf/16v Tantalum x1
10uf/25v Tantalum x4"

I see 13 electrolytics, which probably correspond to the 13 6v tants you have.  He replaced the electros because they were obviously (visibly) bad.  Those Frakos are notorious.

If you want to replace something, replace the 5 higher voltage tants for safety.  I had to do this on a Neve 5422 because several shorted.  Again, a known problem.