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Do tantalum and ceramic cap worth if they save space?

Started by JackSkellington, May 20, 2021, 10:25:05 AM

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JackSkellington

Hello,
It's been some months I began to use 1590A box (there are some thread here :P).
I use film box caps until 2.2uF, when I found it, electrolityc caps for larger value. And ceramic caps for small value, (silver mica are ok, but expensive, and larger).

I used just in power filter monolithic ceramic 100nF and I always avoid tantalum cap.

But, if in a 1590A or 1590G box I have no much space, is it a bad deal to use tantalum or monolithic ceramic caps just beacuse they are smaller?
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matmosphere

I think the 1590a build guide addresses this, but it's been forever since I read it.

I will add though, tantalum caps are supposed to be terrible from an environmental standpoint, so I avoid them. Low profile electo caps are pretty easy to find and can get very small, so I would go that route. Though they are a little more expensive.

As for ceramics, they are fine. Just remember the tolerance is generally not as good as film caps.


madbean

I don't usually use tantalum b/c of the price so I just stick with low profile electros. The fit perfectly and are not expensive. MLCC types are generally okay although I think in certain high gain situations they can be microphonic (this according to Jack Orman but I've yet to experience this issue). I usually use MLCC for anything in the pF range and regular film for everything b/w 1n-470n.

JackSkellington

Low profile electo caps will be ok. I used them, indeed.
The problem are the 470nF, 680nF and the most common 1uF film box I use to buy. Those are pretty ok in larger box, but it could be a problem sometime in smaller box.
If I have to avoid tantalum, and the MLCC types are not always a good... Low profile electo caps win for 0.47uF - 1uF value? :D
«Just because I cannot see it doesn't mean I can't believe it»

madbean

Quote from: JackSkellington on May 20, 2021, 04:28:26 PM
Low profile electo caps will be ok. I used them, indeed.
The problem are the 470nF, 680nF and the most common 1uF film box I use to buy. Those are pretty ok in larger box, but it could be a problem sometime in smaller box.
If I have to avoid tantalum, and the MLCC types are not always a good... Low profile electo caps win for 0.47uF - 1uF value? :D

For those values I would just use MLCC. Like I said, I've never personally run into a microphonics problem using them. It's just something to be aware of.

Willybomb

I just use all those tiny monolithics for those values if I can get them.

JackSkellington

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pickdropper

Quote from: JackSkellington on May 20, 2021, 04:28:26 PM
Low profile electo caps will be ok. I used them, indeed.
The problem are the 470nF, 680nF and the most common 1uF film box I use to buy. Those are pretty ok in larger box, but it could be a problem sometime in smaller box.
If I have to avoid tantalum, and the MLCC types are not always a good... Low profile electo caps win for 0.47uF - 1uF value? :D

One thing to keep in mind is the dielectric of the MLCC in particular.  For low value, COG/NPO are rock solid.  For the larger values, like the ones you talked about above, C0G/NP0 will likely be large and expensive, so you'll end up with X7R (or worse).  MLCC caps derate with temperature, voltage and time.  The one to pay attention to in pedals is voltage.  If you are using a 16V MLCC cap in a 9V pedal circuit, it will likely be below it's rated capacitance if it's seeing close to that 9V (and maybe even considerably less).

This won't hurt anything, it can just sound a bit different.  I built a Klon will all MLCC caps for the 1uF and 4.7uF values and it did sound different.  It does depend a lot on where they are used in the circuit, however.
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madbean

Quote from: pickdropper on May 21, 2021, 11:08:04 AM
This won't hurt anything, it can just sound a bit different.  I built a Klon will all MLCC caps for the 1uF and 4.7uF values and it did sound different.  It does depend a lot on where they are used in the circuit, however.

That's interesting because a few years ago I also built a Klone with all MLCC in place of film and it ended up being one of the best sounding I had come up with.

Zerro

Ceramic caps are more usable for VF blocking close power pins wherever some clicks occur, (LFO gens or clock gens). Generally dielectricum X5R (X7R, X8R). Film caps are better for signal paths, especially with high impedantion stages (J-fet op amps, and especially valve stages), where you work with distortion.

Tantalum caps are better for very good temperature stability and longer time stability, not losing capacity in time. Ceramic caps you want to use, buy some with higher quality (dielectricum NP0 or C0G), otherwise there is not generally good stability in time and they generally get polarised after some time, under some circuit power circumstances. My tip :@)
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pickdropper

Quote from: madbean on May 21, 2021, 01:26:56 PM
Quote from: pickdropper on May 21, 2021, 11:08:04 AM
This won't hurt anything, it can just sound a bit different.  I built a Klon will all MLCC caps for the 1uF and 4.7uF values and it did sound different.  It does depend a lot on where they are used in the circuit, however.

That's interesting because a few years ago I also built a Klone with all MLCC in place of film and it ended up being one of the best sounding I had come up with.

Yeah, the value shift is a real, quantified thing.  It's not some fairy dust audio myth.  The chart below is a decent starting point.  If you like the sound of that Klon, it could very well be because you happen to like lower value caps there.  Now, without knowing the exact caps and the voltage of the caps you use, figuring out exactly how much the capacitance is lowered would likely be difficult.



As you can see in the chart, the derating often starts pretty early on as voltage is applied. 
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pickdropper

Quote from: Zerro on May 21, 2021, 01:37:01 PM
Ceramic caps are more usable for VF blocking od power pins wherever some clicks occur, (LFO gens or clock gens). Film caps are better for signal paths, especially with high impedantion stages (J-fet op amps, and especially valve stages), where you work with distortion. It is clear.

For the most part, I would agree with this.  There are always exceptions, but generally this is the case.

The distortion in MLCC caps is indeed higher, but that's likely not very significant in the context of guitar pedals.  I have run into scenarios at work where that mattered, but guitar pedals are working with much higher signal levels than that was.
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JackSkellington

All these X7R, X5R... I have some confusion.
I found other type in the ceramic cap I can buy.

This is a cheap 1uF monolithic ceramic I could buy.
https://www.taydaelectronics.com/1uf-50v-multilayer-ceramic-capacitor.html
Voltage-Rated: 50V, Tolerance: ±10%, Temperature Characteristic: X7R

This is another one, cheap:
https://www.musikding.de/MLCC-1uF_1
50V, Z5U

This one is more expensive:
https://www.banzaimusic.com/kemet-1uf-63v-z5u-5mm.html
63V Z5U Tolerance: +/- 5%

Should the Tayda's X7R cap be the better? Theorically, at least.
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pickdropper

Quote from: JackSkellington on May 22, 2021, 08:20:28 AM
All these X7R, X5R... I have some confusion.
I found other type in the ceramic cap I can buy.

This is a cheap 1uF monolithic ceramic I could buy.
https://www.taydaelectronics.com/1uf-50v-multilayer-ceramic-capacitor.html
Voltage-Rated: 50V, Tolerance: ±10%, Temperature Characteristic: X7R

This is another one, cheap:
https://www.musikding.de/MLCC-1uF_1
50V, Z5U

This one is more expensive:
https://www.banzaimusic.com/kemet-1uf-63v-z5u-5mm.html
63V Z5U Tolerance: +/- 5%

Should the Tayda's X7R cap be the better? Theorically, at least.

Z5U are worse than X7R.  Like Y5V, there temperature instability is an issue, even in less normal ambient conditions.  The U designator means the tolerance varies +22%/-56% with temp.  You can find more info here:

https://ec.kemet.com/blog/mlcc-dielectric-differences/

Known, vetted MLCC caps are pretty cheap.  I'd skip the Tayda ones and get them from Mouser or Digikey (or some place like that).  They may not even cost more.
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JackSkellington

I often take a look to Mouser, but I find it expensive and it has millions of items that I never found what exactly I wanted. ::)

I'll search some other shop, but I know it's not so ok make an order to buy just some caps in case I need or pay too much what I can find for less money.
We'll see! ;)

Thanks for all the informations.
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