'Blanket' replacing ceramic caps with silver mica, sensible?

[SimontY]

Hi everyone,

I searched, of course, but found slightly contradictory ideas regarding the different types of low-value capacitors.

Anyway, I've been upgrading parts in my cd player for a while (Marantz CD63ki), and have just bought 50 300pf silver mica caps through Ebay, at a fairly good price.

I am thinking of using these to replace all existing ceramic caps in my player, most of which are in digital areas I think.

Is this a safe thing to do sonically, or are there any circuits/uses where this substitution might actually degrade performance?

If noone replies I will do it anyway, and report my listening observations, but I might do other things too, I usually make several changes at once.

Thanks!

 

[BrianL]

Probably not a really smart idea, especially for bypassing
digital power supplies. 300pF is not large enough value
for digital bypassing.

This is not to say you shouldn't/couldn't improve performance
by redoing the digital bypassing. But 300pF micas
aint the way.

 

[sam9]

For bypassing, i.e. establishing a low impedance HF path from power rail to ground I've generally thought that ceramic (usually .001uF to .1uF) is the best choice do the very high bandwidth. A silver mica of similar value is huge in comparrison and expensive as well. Even if SM's were available and practical it wouls seem like a waste to me. A good place for silver micas is where you need a very low value (<1000pF) wideband cap in the signal path or feedback path.

To me bypassing calls more for a blunt instrument than a rapier.

 

[KevinLee]

Hello,

I have use silver mica's in the feedback loop of the op-amps and around the op-amps in my CD63 with good success.

I also have had good success by using polystyrene caps in the same places.

Trial and error is everything.

Thanks

KevinLee

 

[SimontY]

Thanks for the replies everyone!

I won't do it then, save them for something else instead.

Perhaps I will buy better ceramics and use those at some point.


KevinLee,

What positions are these please, can you remember?

 

[Fred Dieckmann]

" Blanket' replacing ceramic caps with silver mica, sensible?"

Either sounds like would be heavy, uncomfortable, and not very warm. Have you considered wool? It's been done to death I know, but it gives the sheep something to do. Whoops! ....... I reread your post and see that I have perhaps missed your intentions.

 

[sam9]

If you are looking for improvement by replacing caps, I would suggest you start by trying to figure out where the output cap is. Increasing the value (unless it is already ok) has the potential to lower noise and extending the base response.

As an aside, I recall a 70's era reciever that claimed as a feature that it had an "integral rumble filter". What this meant was that they had stuck an itty-bitty 2uF cap in in the input. Each of the inputs, not just the phono. Now there's creative marketing. Making a "feature" out of a cost saving.

 

[SimontY]

If you are looking for improvement by replacing caps, I would suggest you start by trying to figure out where the output cap is. Increasing the value (unless it is already ok) has the potential to lower noise and extending the base response.

As an aside, I recall a 70's era reciever that claimed as a feature that it had an "integral rumble filter". What this meant was that they had stuck an itty-bitty 2uF cap in in the input. Each of the inputs, not just the phono. Now there's creative marketing. Making a "feature" out of a cost saving.

Thanks, but I've taken the output caps out already, this was one of the biggest upgrades I've done to it. Removed a whole layer of sludge from the sound.

I've also changed many PSU caps, resistors, some diodes, the output op-amps, added shielding, reclocked, built supply for the clock, added damping, changed feet, etc. So I am down to a few little things now I think, hehe.

 

[KevinLee]

Hello SimontY,

Here are the locations in my CD63 where I installed silver mica caps:

-CD21, CD22, CD23, CD24
-C602, C602, C603, C604
-C605, C606
-C607, C608

I am going to assume you removed QN05, QN06, QN07 and QN07, If you have not you should. Removing these muting transistors is a great mod in the CD63/67 players.

Also try installing a .01uf ceramic from input (pin 2) to ground (pin 16) on the (3) TCA0372 chips.

Good luck

KevinLee

 

[SimontY]

Thanks Kev, I'll look at doing those replacements. I did remove the muting transistors, altho I can't remember it making a very big difference to the sound.

I will try some caps on the chips too, great!


Thanks

 

[SimontY]

Hi again,

I 'popped the hood' on my player again last night, and was so tired I wrecked the solder pads for two components and accidentally smashed 2 ceramic caps.... oops!

But today I had another, less tired attempt at things, I -
- bypassed the 3 TCA0372 chips from 2 to ground at 16, I have no ceramics so used 22nF Wima
- added an earth post to the chassis
- bypassed a random 'lytic or two
- started shielding op-amps but ran out of time to finish
- nuded a large smoothing cap
- added some ground jumpers around the place, underneath
- replaced C106 with 35uF tantalum and mica - broke the pads so soldered it across the next points on the back
- added 0.0047uF x2 cap to 'bypass' 0.33uF x2

Only had a quick liste (it's late) and it works, yay! Seems to offer some more detail and texture, but only a quick listen - I could *easily* have imagined that... altho. I did hear a distinct crackling noise on an Eleneor McEvoy track, which I've never picked up before, so it's promising...

Thanks for the guidance folks, as ever!

 

[SimontY]

Ah, I took a pic of the back, doesn't look like *this* stock