View Full Version : Preffered film caps to replace ceramic caps?


rg12
08-27-2010, 09:35 AM
I wanted to know which film caps do you recommend to replace
ceramic caps in my Pioneeer SA-7300 amp.

I need:
0.022
0.1
0.0056
0.0012

I prefer that it will be from the same series but i couldn't find those 0.0056 and 0.0012.

Which brand is preffered?

I need a place with international shipping (not mouser, the international shipping there is $40!).

Roi.

Grainger49
08-27-2010, 09:44 AM
I guess it depends on where in the circuit it is. An audio path cap could be replaced with a Teflon film cap, Polypropylene film/foil cap, Polyethylene film/foil cap. If it is an equalization cap that takes a signal to ground metalized Polypropylene film or a silver mica cap?

There is a world of manufacturers for the Polypropylene film/foil caps. Probably 2-3 dozen. Some of the suppliers are out of the US to start with. For instance many of the USSR Military Surplus sellers are in Ukraine, Parts ConneXion is in Canada, DIY HiFi Supply is in Hong Kong. Where are you now?

Jon_Logan
08-27-2010, 09:45 AM
If the caps that you want to replace are in the tuner circuit or logic IC bypass caps, I don't recommend that you change to film types.

For RF, there are no better caps then ceramics for that application. If you were talking analog signal path, sure go ahead. but I've never seen ceramics used as coupling caps in any decent equipment.

rg12
08-27-2010, 10:29 AM
They are all in the signal ground.

Hyperion
08-27-2010, 10:42 AM
If the caps that you want to replace are in the tuner circuit or logic IC bypass caps, I don't recommend that you change to film types.

For RF, there are no better caps then ceramics for that application. If you were talking analog signal path, sure go ahead. but I've never seen ceramics used as coupling caps in any decent equipment.

+1
What he said.

They are all in the signal ground.

not sure what you mean here...

rg12
08-27-2010, 10:57 AM
+1
What he said.



not sure what you mean here...

Never mind, it's ok, my friend from another forum confirmed these caps.

What is preffered, metalized polypropylene or silver mica? and what is the difference? i got metalized polypropylene in the signal path and i like them very much.

nashvillebill
08-27-2010, 04:34 PM
Why not post a schematic and tell us which ones you are referring to?

I really, really doubt Pioneer would put a ceramic in the signal path. Guitar amps sure, but not in a home stereo.

My recommendation, leave 'em alone. "my friend from another forum confirmed these caps" may or may not be good advice.

Post a schematic!!

Wazz
08-27-2010, 08:33 PM
Ceramic caps were in the signal paths in old tube gear and some early solid state for sure. Coupling and tone controls for one. I would replace them with polyproplene types of the same value and voltage rating at least. The trick is, will they fit? Polyesters are sometimes the smallest of film caps but are not always first choice in audio gear. But perhaps better than ceramics. The small value ones you mentioned might be something critical? Like in phono circuit EQ or something? Therefore you want to have close tolerance values in feedback and tone control circuits. For coupling caps the tolerances are not so super critical. The smaller values you gave might be available in polystyrene versus polyproplene. Or even in teflon. Polystyrene is supposed to be a superior cap to PP. but are more expensive and are not made in very large values. Many of the spec sheets on the caps give the dimensions in millimeters but that has to be considered when deciding if they will fit in the space you have. I have done mods with big fat old film caps, say a 1 uF film replacing a small 1 uF electrolytic, but it often looks awkward and a poor fit. Sometimes you can attach bigger caps on the back side of the board easier than in the space between components. In tube gear, there is usually plenty of space as you are replacing something like a large paper foil cap with a maybe smaller film type.

nashvillebill
08-27-2010, 11:29 PM
Well maybe I should have qualified my statement when I said "I really doubt Pioneer would put a ceramic in the signal path"...this is almost certainly a late '70's ( or later) amp and definately solid state.

So I STILL really, really doubt there are ceramics in the signal path, though I agree *possibly* one or two may be in a tone control. "Signal ground" as he described earlier, tells us nothing.

We need a schematic.

riverRatt
08-27-2010, 11:48 PM
... and if ceramic caps in the signal path are replaced with any of the above recommended types. How will this change the sound?

rg12
08-28-2010, 04:12 PM
Here is the schematic: Caps numbers: c27 c28 c29 c30 c31 c32 c33 c34
http://www.milkbands.co.il/Pioneer-SA-7300-int-sch.pdf

So far i got sound changed from caps that aren't in the signal path
and i couldn't believe how big the difference was, so i don't believe in
changing the caps in the signal path only.

Also, it is a late 70's integrated amp and i guess most electrolytic caps are
dry and half dead, so recapping could only help.

After replacing the two big filter caps in the power section of the amp,
the whole amp sound changed even more that the signal path recap did a change!

What is the difference in sound between silver mica and polypropylene?

About the cap size differences, i found the place and they sit good, even
though they are 20 times bigger than the a few tantalums i replaced with
polypropylene.

nashvillebill
08-29-2010, 10:09 AM
Well how about that, the ceramics *are* in the tone control circuit.

I definately would change all the electrolytics in that amp, because the old ones are at the end of their life.

But if it were my amp I'd leave these ceramics alone. Several reasons: a) it's more work and I've already got too much to do as it is, b) changing components can cause the traces to lift on the PCB's so why hassle with unnecessary changes, and c) I'm not a believer in the "more expensive caps sound better" theory.

rg12
08-29-2010, 11:33 AM
If they are located in the tone control, how can it not affect the sound?

I changed all the electrolytics and the amp got a new life, increased power,
cleaner sound etc...

And yeah, i lifted some traces on the pcb in the area where the component is being soldered (i didn't tair it though).

nashvillebill
08-29-2010, 01:15 PM
Because, IMHO, the type (or price) of capacitors do not have as much effect on sound as some folks claim. Many exceptional-sounding amps use plain, garden-variety caps, including electrolytics, ceramics, and tants. (It's the design, not the price of the component).

A good in-depth read can be found online here http://sound.westhost.com/articles/capacitors.htm

Rod Elliott has a number of articles on his website where he debunks a lot of audio myths. While there are a number of measurable capacitor characteristics that may fall into play when choosng a cap for a circuit (ESR, ESL, non-linearity, etc), not every audio application will benefit from changing from one type of cap to another, again IMHO. In fact, going to a larger/different cap with longer/wider lead spacing can increase its inductance--NOT a good thing with tone control caps.

Wazz
08-29-2010, 07:20 PM
Perhaps a longer cap will have more inductance but at what frequency will that have an effect? 200 KHz? Megahertz? Hard to say. The Audio magazine article said that ceramics can introduce their own measurable distortions. Not huge, but remedied with better film types. Whether or not you could hear any difference without the old cap being out and out defective in some parameter is debatable. I remember looking inside of my GAS Thoebe preamp. I was happy with the superb build quality I observed. I also saw a fair number of ceramics on the PC cards as I recall. I replaced it with a much newer design Hafler preamp at the time and it was a notable improvement in some aspects of audible performance though. But the Hafler was not built like a battleship like the GAS unit, although better by far than alot of gear. I suppose installing better quality parts might result in some satisfaction and peace of mind, if not a particularly noticeable audible improvement. I am amazed that sometimes reviewers audition an "upgrade" of a known unit, usually a mfr. Mk. II version of some model, and hear all kinds of improvement from some simple or seemingly insignificant change.

riverRatt
08-29-2010, 09:47 PM
On the subject of cheap cap vs. expensive cap: I read somewhere that using two cheap caps in parallel can perform as good as a single expensive cap. (something about lower ESR) Is there any truth in this?

This is a little off subject, but I, also, remember reading that when two caps have the same specs but with different physical sizes that it is better to choose the cap that is physically larger. Again, is there any truth in this?

rg12
08-29-2010, 10:04 PM
From what i heard, bigger caps (due to higher voltage), can be more detailed in sound, although they have the same capacitance and are from the same
brand and series, but it's just an article i read about high quality audio caps.

rg12
08-30-2010, 12:37 PM
Some new findings...

OK here is a nice pic of the amp with the treble and bass caps
marked in red: http://www.milkbands.co.il/caps.jpg

The disc caps are for the treble and the green ones (NP1) are for
the bass.

Also, the right red circle shows the same cap pattern but for the balance
pot. If i mod the bass and treble, would i benefit from replacing the balance caps too?

Why don't they write the capacitance value on the disc caps and NP1 caps? i found them by the copper tracks and not by the values (because
they only have numbers that aren't related to capacitance value as far
as i can see).

What do you recommend doing to improve the sound? to replace them
to which type? Also, i always place the bass pot very low (3 out of 10
in the marks of the face panel) because the bass is very "closed"
very "smudgy", so what can i do to make it more accurate and punchy?

About the treble...i don't like those disc caps...

What do you guys think?

backmd
06-04-2011, 01:15 AM
I wanted to know which film caps do you recommend to replace
ceramic caps in my Pioneeer SA-7300 amp.

I need:
0.022
0.1
0.0056
0.0012

I prefer that it will be from the same series but i couldn't find those 0.0056 and 0.0012.

Which brand is preffered?

I need a place with international shipping (not mouser, the international shipping there is $40!).

Roi.

see below

http://www.reliablecapacitors.com/pickcap.htm