Parallel vs. series vs. one filter cap

[Leo_Gnardo]

If you are doing a repair and it is a multi-section cap that is at fault, snip its connections to the circuit and install a new cap inside the chassis. This maintains stock appearance but provides much better filtering.

Exactly how I re cap Princetons, Champs & other amps with old multisection caps.

At the other end of the power scale, 70's Ampeg V4 and similar amps get film caps rated for 800 or 900V.

Kevin, your recommendation is to avoid IllNoise & F&T, no problem. What electrolytics do you recommend? Do you have a rec. for cathode bypass caps? And what do you think of film filter caps? Carr uses Solen in their builds, and I've used Solen successfully in some repairs up to 600V. I've also used Panasonic and Cornell-Dubilier polypropylene 800 & 900V, a pain to mount due to their rectangular form but the seem to work just fine in circuit and I predict they'll last practically forever, let's say beyond my customers' lifetime.

Have fun!

Keep reminding me.

[KevinOConnor]

Hi Guys

I guess it was another thread where i listed good brands: Panasonic, Nichicon, United Chemicon, TDK, Epcos, Cornell-Dublier.

Note that you have to read the data sheets or at least look at the life expectancy. For example, Nichicon VZ or Panasonic FCs are only 1,000-hour caps, where Nichicon HEs and Panasonic EDs and EEs are 10,000-hour caps. The long life caps do not cost much more if at all compared to the low-life caps. This rating is at maximum temperature and doubles with each 10C below for actual temp.

There are generally no issues with plastic caps as they are much better to begin with than electrolytics as far as approaching being an ideal cap. Don't waste money on voodoo brands (Zoso, Mustard, Orange-drop) or anything that says "audio grade" in the description. These are all usually priced much higher for a given value and are truly generic poly caps.

Polys for supply filtering will clean up the signal and you will either like it or find something is missing. What is missing is electrolytic distortion. These caps are at least seven-times larger by volume - more these days - compared to electros, so not an easy retrofit but okay if it's a new build and a big chassis. Solen are the best type of cap for this app, reasonably priced and shaped. I used Solen filter caps before Carr did.

Have fun

[engineer_musician]

I prefer parallel caps for a few reasons.
1. Series caps require voltage divider resistor in parallel with the caps to make sure they share the voltage equally. Without them the 2 caps leakage currents may be so different that one of them will have too much voltage.
2. All caps have an internal Effective Series Resistance, ESR. The greater the uF the greater the ESR and when you put caps in series you need double the uF because in series it's 1/2 the value for 2 caps of equal value.
3. Parallel caps can be lower value because their uF add and the lower uF means a lower ESR and putting them in parallel means the total ESR is now 1/2 of the 2 caps.

[Mike Sulzer]

I prefer parallel caps for a few reasons.
1. Series caps require voltage divider resistor in parallel with the caps to make sure they share the voltage equally. Without them the 2 caps leakage currents may be so different that one of them will have too much voltage.
2. All caps have an internal Effective Series Resistance, ESR. The greater the uF the greater the ESR and when you put caps in series you need double the uF because in series it's 1/2 the value for 2 caps of equal value.
3. Parallel caps can be lower value because their uF add and the lower uF means a lower ESR and putting them in parallel means the total ESR is now 1/2 of the 2 caps.

From earlier:

"13 100 micro f 450 v capacitors found in a catalog have an average ESR of 1.88 ohms. The two 220 v 220 micro f caps I found had .905 ohms ESR. Seems like a series connection of two can be just as good. Or maybe not if you choose the wrong capacitors."

[engineer_musician]

In this case you're right.

[Wombaticus]

2. All caps have an internal Effective Series Resistance, ESR. The greater the uF the greater the ESR

No, you have this backwards. ESR *decreases* approximately linearly with increasing capacitance, at least when considering caps within the same product line and manufacturer. So since series connection requires doubling the capacitance of each cap, ESR will generally be a wash in series vs. individual caps. Same deal with parallel vs. individual... paralleling smaller capacitance caps to get the equivalent capacitance to a single individual cap generally buys you nothing with respect to ESR.

[engineer_musician]

That's not always true. To compare apples to apples, if we double the C and 1/2 the V as per this discussion, it's about even, ignoring Xc = 1 / (2 Pi F C), there is a point where one crosses the other, note page 2.
http://www.illinoiscapacitor.com/pdf...factor_esr.pdf
Note the chart on page 9 where it shows 100uF caps of different voltages. As voltage goes down ESR goes up. I haven't fould the other chart yet, but it's out ther, as C goes up ESR goes up for the same voltage.
http://www.niccomp.com/help/ESR-Ripp...age-032012.pdf

[Pedro Vecino]

I do not understand why is not considered advisable F&T capacitors. I've been wearing them a long time and with big number and have never had problems with them. Can anyone believe that in Germany are manufactured electronic components with low quality? To sell where?
The problems with Illinois electrolytic capacitors (certain series, not all) are somewhat unique and no admits parallels, if not with very low quality capacitors in consumer/domestic electronics.

[Justin Thomas]

Just because something is "old technology" doesn't mean we should just dispense with it altogether. I mean, if that was the case, WTH are we still doing talking about using electrolytic caps for power supplies for THERMIONIC VALVES? I mean, those stupid things are 100+ years old.

And, perfection is not always the goal. It's a guitar amp, a weapon of SONIC destruction, not an ICBM, where if you're 5% or 20% off, it blows up your best wartime ally instead of your enemy. And yes, sometimes aesthetics matter. I really LIKE opening up an amp and seeing that shiny black casing with gold squiggles on it, best looking caps out there, and not stupid-priced like most of the others.

Justin

[Bishop]

I do not understand why is not considered advisable F&T capacitors. I've been wearing them a long time and with big number and have never had problems with them. Can anyone believe that in Germany are manufactured electronic components with low quality? To sell where?
The problems with Illinois electrolytic capacitors (certain series, not all) are somewhat unique and no admits parallels, if not with very low quality capacitors in consumer/domestic electronics.

It seems to me as though he is referring to the multi-section caps, possibly not because they are F&T but because that style cap is generally out-dated in reality.

[soundmasterg]

Hi Guys

I wouldn't use the Spragues or the F&Ts or any other multi-section cap. Being old technology designs they are not as good as new-technology electrolytics - with electros newness is a benefit in their design and manufacture. Every electro will last a long time if it has regular application of voltage, as I stated earlier. This just means they will last a long time but does not mean that their DA does not rise over time - which it does - making them less ideal as they age.

The multi-section caps when used as intended compromise good grounding. If you are doing a repair and it is a multi-section cap that is at fault, snip its connections to the circuit and install a new cap inside the chassis. This maintains stock appearance but provides much better filtering.

Have fun

I wasn't talking about multi-section caps. If I use those, I try to parallel the sections, and I only use them if I am space limited, which is usually only if I am repairing some old amp that doesn't have room for caps under the chassis. That occasion is rare.

In the case of Sprague Atoms, I haven't used those for years....way too expensive and they are much larger than modern caps. They also are these days just a smaller cap inside the large body and pretty much a waste of money.

In the case of F & T, I was talking about their axial caps. They function fine, as in I have never had a bad one and I've used them for a lot of repairs for years. I've also used Xicon, Nichicon, Panasonic, with no issues. I never use Illinois as they are usually not very reliable...I've had several of those fail in the past. So in the case of F & T axials, they seem to be just as good as any other modern axial. A radial would likely be better, but those sometimes don't fit into vintage amp designs as well. I don't know if F & T makes radial caps, though I would bet they likely do. I also haven't looked for any datasheets, though I would guess they are probably out there for the F & T's. The question remains however....are you recommending to not use any F & T and are you saying they are old tech, or are you just recommending against using multi-section can caps?

Greg

[nickb]

I wasn't talking about multi-section caps. If I use those, I try to parallel the sections, and I only use them if I am space limited, which is usually only if I am repairing some old amp that doesn't have room for caps under the chassis. That occasion is rare.

In the case of Sprague Atoms, I haven't used those for years....way too expensive and they are much larger than modern caps. They also are these days just a smaller cap inside the large body and pretty much a waste of money.

In the case of F & T, I was talking about their axial caps. They function fine, as in I have never had a bad one and I've used them for a lot of repairs for years. I've also used Xicon, Nichicon, Panasonic, with no issues. I never use Illinois as they are usually not very reliable...I've had several of those fail in the past. So in the case of F & T axials, they seem to be just as good as any other modern axial. A radial would likely be better, but those sometimes don't fit into vintage amp designs as well. I don't know if F & T makes radial caps, though I would bet they likely do. I also haven't looked for any datasheets, though I would guess they are probably out there for the F & T's. The question remains however....are you recommending to not use any F & T and are you saying they are old tech, or are you just recommending against using multi-section can caps?

Greg

The claim that F&Ts are old tech and unreliable is just plain false - I checked. Also a look at the datasheet confirms that they have comparable characteristics to the the other brands mentioned - 4000 hour life a 85C. If we assume your caps are running at 55C ( too hot to touch) then the life is 32,000 hours or 43 years at 2 hours a day use.

There isn't a single answer to your original question - which arrangement is best. One would assume that you are using different brand/voltage/construction for the two arrangements and therefore you have to look at the data and costs for each and calculate the performance to get an answer. But first and most important, for audio applications the difference is negligible. The most important things are to meet the working and surge voltage requirements and stay within the ripple current rating.

[KevinOConnor]

Hi Guys

Multi-section caps should be avoided inasmuch as they make it easy to compromise the grounding of an amp if you wire them as intended. Rather, as TUT3 shows, wire the sections in parallel and use it as a single cap.

Years ago when CE Distribution started carrying multi-section caps, the ones they got in were essentially copies of the old-style metal can with lugs, I forget the brand but it was something with two initials, like F&T or JJ. There were no data sheets on the site then as there is now. The F&T axials listed today are okay quality but axials are not as reliable as radials in my experience. Back in the 1980s and '90s one could get the Mallory CG-series axials but then their pricing went crazy, which is why I switched to radials for all repairs. I only use 10khr+ radial-lead and snap-mount electros in my amps wherever electros are used. I use parallel caps for the first filter to assure best noise and filtering performance. Until recently, I never needed anything more than a 450V rating but now have to use some 500V caps in some places. Fortunately these cost little more than the 450Vs.

The F&T pricing certainly does not convince me to buy them. I'll stick with the brands I mentioned above, available from the broad-line electronics distributors. I'm sure F&T is more widely available in Europe, but they only wseem to be available from specialty places in north America, places catering specifically to tube amp construction.

Have fun

[soundmasterg]

Here is the apparent home site for F & T, which can be translated into English. I couldn't tell if there are radial caps there aside from ones without leads and just having solder contacts, and of course radial can caps too. It sounds like they custom make stuff so I am sure you could have a bunch made if you had a ton of money. Sounds like they have been around for a long time though, and looking at the specs it seems like they make good quality stuff.

Greg

FTCAP Fischer und Tausche Capacitors - FTCAP GmbH