How to deal with changed ESR?

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33na3rd

How to deal with changed ESR?
« on: 1 Jun 2016, 01:18 am »
I'm in "exploring options" mode.

My Audio Physic Virgo 2's are approaching 20 years of service. I have noticed that the tonal balance has been slowly changing. The crossover uses 7 Electrolytic caps per side. (Four InterTehnik ELXO Glatt that I know of, I can't see the other three without unsoldering crossover leads.) I believe that these caps are starting to show their age, and it appears that they are no longer available.

It's my understanding that if I replace these caps with something else of the same value, that the ESR will change, requiring either new resistors of a new value or installation of a L-Pad to keep the tweeter & mids balanced correctly.

In the pictures I've seen on the web from folks who have redone their crossovers, I have seen very few L-Pads.

I'm assuming that folks are changing the resistors instead?

How does one figure out a new resistor value, or is it trial & error?

Or is the ESR change less of an issue than I think?

Thanks,
Jeff

Stimpy

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Re: How to deal with changed ESR?
« Reply #1 on: 2 Jun 2016, 03:05 am »
I'm far from an expert, but I have been studying about this too, over the last few months.  According to what I've read, changes to ESR only come into play if you change your capacitors from electrolytic, to polypropylene or film caps.  If replaced with electrolytic, the ESR values shouldn't shift enough to be audible.  Mylar caps also exhibit a similar ESR value to electrolytic's.  Some users like to upgrade with mylars in the tweeter circuit, and poly's for the mids/bass, to avoid excess brightness.

Now, if upgrading to poly caps, the ESR will be lower.  How much lower is up for debate.  It seems that a capacitor's ESR value shifts with frequency, and the value isn't exactly set.  Though, typically, ESR only changes (drops) anywhere from 0.1 Ohm, to maybe no more than 0.5 Ohm, when upgrading to poly's.  Not a huge shift.  The ESR shift can be audible, but it may or may not be objectionable.  It just depends if you like the treble a little brighter or not?

As a fix for the lower ESR, you can add (solder) a low value resistor in series (end to end) with the poly cap.  You can try several values, if needed, to tweak the high end response to your liking.  Use a decent resistor, with a least a 5 watt rating for the tweeter.  Ten watts or better, if you like higher volume levels.  Let the new caps break in for a week or two, to let them settle in, then if the tweeter is still too hot, start experimenting with adding a resistor.

Hope this helps?

33na3rd

Re: How to deal with changed ESR?
« Reply #2 on: 2 Jun 2016, 05:13 am »
I'm far from an expert, but I have been studying about this too, over the last few months.  According to what I've read, changes to ESR only come into play if you change your capacitors from electrolytic, to polypropylene or film caps.  If replaced with electrolytic, the ESR values shouldn't shift enough to be audible.  Mylar caps also exhibit a similar ESR value to electrolytic's.  Some users like to upgrade with mylars in the tweeter circuit, and poly's for the mids/bass, to avoid excess brightness.

Now, if upgrading to poly caps, the ESR will be lower.  How much lower is up for debate.  It seems that a capacitor's ESR value shifts with frequency, and the value isn't exactly set.  Though, typically, ESR only changes (drops) anywhere from 0.1 Ohm, to maybe no more than 0.5 Ohm, when upgrading to poly's.  Not a huge shift.  The ESR shift can be audible, but it may or may not be objectionable.  It just depends if you like the treble a little brighter or not?

As a fix for the lower ESR, you can add (solder) a low value resistor in series (end to end) with the poly cap.  You can try several values, if needed, to tweak the high end response to your liking.  Use a decent resistor, with a least a 5 watt rating for the tweeter.  Ten watts or better, if you like higher volume levels.  Let the new caps break in for a week or two, to let them settle in, then if the tweeter is still too hot, start experimenting with adding a resistor.

Hope this helps?




It does help, Stimpy. Thank you.

It sounds like having the crossover outboard might make these adjustments easier.
« Last Edit: 2 Jun 2016, 03:24 pm by 33na3rd »

Stimpy

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Re: How to deal with changed ESR?
« Reply #3 on: 2 Jun 2016, 10:04 pm »
Those Audio Physic Virgo 2s look really nice.  German speakers with 3/4" metal domes tweeters, which are typically designed for a neutral/flat response, so you should be concerned with ESR shifts when changing the caps.  If sticking with electrolytics, Mundorf has E-Caps, that are very good, plus affordable.  Then there's always Erse or Bennic.  Poly, there are lots of 'affordable' choices; Mundorf, Sonicap, Audyn Q4, or Plus, ClarityCap PX, SA, or ESA, Dayton, Erse Pulse X, and Jantzen CrossCap or Superior caps.  Jeff has many other choices as well!    :D

An outboard crossover sounds nice too.  Does the speaker allow for that?  You'd have to of course at least disconnect the internal crossover, and possibly mod the cabinet to accept inputs for the tweeter, mid, and woofers.  Plus, you might want to use the existing crossovers for parts donor units, and reuse the original inductors, because changing coils can shift the sound as much as changing the caps.  Maybe do one parts swap at a time, in order to tell how effective a change has been.  Then proceed to the next!

33na3rd

Re: How to deal with changed ESR?
« Reply #4 on: 2 Jun 2016, 10:35 pm »
They Virgo's have been very good speakers, and work really well in my small square room.

I would have to be very careful indeed with the ESR shifts, especially with the tweeter as my ears shy away from "too much" brightness. I tend to like a sound that's just a bit warmer than "neutral".

I was concerned that adding an outboard crossover would negatively affect the aesthetics/potential resale value of the speakers, if I were ever to try selling them. After a quick internet search, I discovered that they aren't worth much these days, so no worries!

Using a Nuetrik Speakon connection would tidy things up if I decide to put the crossover outboard.

Thank you for the suggestions. I will have to check all these out!

My brain is still trying to process the fact that much of my gear that I bought new is now "vintage"!


Stimpy

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Re: How to deal with changed ESR?
« Reply #5 on: 2 Jun 2016, 10:48 pm »
Using a Nuetrik Speakon connection would tidy things up if I decide to put the crossover outboard.

A Speakon connector works really well for adding an outboard x-over.

Thank you for the suggestions. I will have to check all these out!

No problem.  You're welcome.

My brain is still trying to process the fact that much of my gear that I bought new is now "vintage"!

I don't mind my gear becoming vintage.  What bothers me is that I'm vintage now too...!!!    :evil:

Jeff

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Re: How to deal with changed ESR?
« Reply #6 on: 3 Jun 2016, 04:54 am »
The ESR of your original capacitors was very low when they were new, so ESR here is a none issue.  I have modified a couple.  I'm looking around for a couple of photos...  In any event, it is important to select warm film caps when replacing electrolytics in a previously balanced speaker.  You have nothing to worry about, and I would not move to an outboard XO unless you plan on playing with them a lot.  It seems like a mere 6 screws has them out.

Jeff

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Re: How to deal with changed ESR?
« Reply #7 on: 3 Jun 2016, 04:56 am »
I don't mind my gear becoming vintage.  What bothers me is that I'm vintage now too...!!!    :evil:

LOL :lol:  Me too :cry:

G Georgopoulos

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Re: How to deal with changed ESR?
« Reply #8 on: 3 Jun 2016, 05:28 am »
Quote

Capacitors[edit]
In a non-electrolytic capacitor and electrolytic capacitors with solid electrolyte the metallic resistance of the leads and electrodes and losses in the dielectric cause the ESR. Typically quoted values of ESR for ceramic capacitors are between 0.01 and 0.1 ohms. ESR of non-electrolytic capacitors tends to be fairly stable over time; for most purposes real non-electrolytic capacitors can be treated as ideal components.

Aluminium and tantalum electrolytic capacitors with non solid electrolyte have much higher ESR values, up to several ohms, and ESR tends to increase with frequency due to effects of the electrolyte. A very serious problem, particularly with aluminium electrolytics, is that ESR increases over time with use; ESR can increase enough to cause circuit malfunction and even component damage,[1] although measured capacitance may remain within tolerance. While this happens with normal aging, high temperatures and large ripple current exacerbate the problem. In a circuit with significant ripple current, an increase in ESR will increase heat dissipation, thus accelerating aging.

Electrolytic capacitors rated for high-temperature operation and of higher quality than basic consumer-grade parts are less susceptible to become prematurely unusable due to ESR increase. A cheap electrolytic capacitor may be rated for a life of less than 1000 hours at 85°C (a year is 8760 hours). Higher-grade parts are typically rated at a few thousand hours at maximum rated temperature, as can be seen from manufacturers' datasheets. Electrolytics of higher capacitance have lower ESR; if ESR is critical, specification of a part of larger capacitance than is otherwise required may be advantageous.

Polymer capacitors usually have lower ESR than wet-electrolytic of same value, and stable under varying temperature. Therefore, polymer capacitors can handle higher ripple current. From about 2007 it became common for better-quality computer motherboards to use only polymer capacitors where wet electrolytics had been used previously.[2]

The ESR of capacitors of relatively high capacity (from about 1 μF), which are the ones likely to cause trouble, is easily measured in-circuit with an ESR meter.




never had a problem with esr,but the quote above provides 101 info on esr
this is also interesting in that keeping equipment turned on 24/7 effects the esr


33na3rd

Re: How to deal with changed ESR?
« Reply #9 on: 3 Jun 2016, 03:10 pm »

I don't mind my gear becoming vintage.  What bothers me is that I'm vintage now too...!!!    :evil:

Stimpy, I resemble that remark! :)

The ESR of your original capacitors was very low when they were new, so ESR here is a none issue.  I have modified a couple.  I'm looking around for a couple of photos...  In any event, it is important to select warm film caps when replacing electrolytics in a previously balanced speaker.  You have nothing to worry about, and I would not move to an outboard XO unless you plan on playing with them a lot.  It seems like a mere 6 screws has them out.

Thanks Jeff! I'm feeling better & better about this!

never had a problem with esr,but the quote above provides 101 info on esr
this is also interesting in that keeping equipment turned on 24/7 effects the esr



Some good information there, thank you! I initially thought the main differences between caps was their sonics. Until recently, I didn't realize that the film types have a longer service life.

Jeff

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Re: How to deal with changed ESR?
« Reply #10 on: 4 Jun 2016, 04:16 am »
never had a problem with esr,but the quote above provides 101 info on esr
this is also interesting in that keeping equipment turned on 24/7 effects the esr

None of that is really useful for XOs.  However, while you are there, the speced service life of an electrolytic (say 1000 hrs) is worse case scenario at max temp and max ripple rejection.  Said cap can last 20-30 years in audio equipment.

Jeff

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Re: How to deal with changed ESR?
« Reply #11 on: 4 Jun 2016, 04:26 am »
I initially thought the main differences between caps was their sonics.

And you were right.  However, near 100% of the electronics industry does not observe that.  Further, greater than 99.9% of capacitor applications do not involve sonic enjoyment.  This is even true for many audio applications.  These parts are therefor strictly described by almost every other characteristic.

Quote
Until recently, I didn't realize that the film types have a longer service life.

This is true, but this is the last reason I would use for switching to film.  At our age, current quality electrolytics are likely to go about as long as we have left  :wink: :lol:

G Georgopoulos

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Re: How to deal with changed ESR?
« Reply #12 on: 4 Jun 2016, 04:44 am »
None of that is really useful for XOs.  However, while you are there, the speced service life of an electrolytic (say 1000 hrs) is worse case scenario at max temp and max ripple rejection.  Said cap can last 20-30 years in audio equipment.

sir, bipolar electrolytics are similar to monopolar ones only 2 back to back,esr is effected, will rise with age,i have seen lots of bipolars in crossovers,in my experience they have been reliable,but they will eventually age and rise the esr with use,if you dont believe me just google wikipedia.


Quote
This is true, but this is the last reason I would use for switching to film.  At our age, current quality electrolytics are likely to go about as long as we have left 


film caps are solid dielectric meaning it last longer than electrolyte,what you claim is false,modern electrolytics do age faster than film see this https://en.wikipedia.org/wiki/Equivalent_series_resistance

cheers


Jeff

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Re: How to deal with changed ESR?
« Reply #13 on: 4 Jun 2016, 06:14 pm »
sir, bipolar electrolytics are similar to monopolar ones only 2 back to back,esr is effected, will rise with age,i have seen lots of bipolars in crossovers,in my experience they have been reliable,but they will eventually age and rise the esr with use,if you dont believe me just google wikipedia.


film caps are solid dielectric meaning it last longer than electrolyte,what you claim is false,modern electrolytics do age faster than film see this https://en.wikipedia.org/wiki/Equivalent_series_resistance

cheers

Easy there George.  You do not appear to understand my reply, and I do not understand your rebuttal.  However, I can assure you that I do not need wikipedia to support my position.  If you have a problem with certain points, call them out specifically, and I would be happy to enlighten you.

G Georgopoulos

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Re: How to deal with changed ESR?
« Reply #14 on: 7 Jun 2016, 01:31 am »
Easy there George.  You do not appear to understand my reply, and I do not understand your rebuttal.  However, I can assure you that I do not need wikipedia to support my position.  If you have a problem with certain points, call them out specifically, and I would be happy to enlighten you.

please do so,cause i dont know what you're talking about?,fact is electrolytics age,forget wikipedia,specifically my own point.

Jeff

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Re: How to deal with changed ESR?
« Reply #15 on: 8 Jun 2016, 02:07 am »
please do so,cause i dont know what you're talking about?,fact is electrolytics age,forget wikipedia,specifically my own point.

I said and implied a lot.  Yet, you have challenged me on something very elementary.  Which I never said, or implied to start with :wink:  You lost the trail in a previous post:

Quote
what you claim is false,modern electrolytics do age faster than film

I never made that claim.  I assumed you would figure out your mistake at some point.  I was more concerned with the snippet you copied from....  I did not want it to divert anyone away from what I feel to be more important considerations regarding XO applications.  Whomever originally wrote that information would have readily told you that its focus is more on power supply caps, not XO caps.

G Georgopoulos

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Re: How to deal with changed ESR?
« Reply #16 on: 8 Jun 2016, 02:40 am »
I said and implied a lot.  Yet, you have challenged me on something very elementary.  Which I never said, or implied to start with :wink:  You lost the trail in a previous post:

I never made that claim.  I assumed you would figure out your mistake at some point.  I was more concerned with the snippet you copied from....  I did not want it to divert anyone away from what I feel to be more important considerations regarding XO applications.  Whomever originally wrote that information would have readily told you that its focus is more on power supply caps, not XO caps.

Jeff mate i have not challenged you,i only put my opinion and experience across    :wink:
 cheers mate

Jeff

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Re: How to deal with changed ESR?
« Reply #17 on: 8 Jun 2016, 02:56 am »
George, when I say challenge, it is in the spirit of a well meaning debate, not an uncivil argument.  I assume we are all adults here, and have the ability to debate passionately without strife.  I just did not think you understood my position.  Likely due to the brief manner in which I often deliver my position.  I do this in the interest of time, and wait for specific questions, or a challenge of my position.  Cheers :)

undertow

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Re: How to deal with changed ESR?
« Reply #18 on: 28 Jul 2016, 06:06 pm »
Since this topic looks on key to a burning debate I have...

Riddle me this.

I was absolutely assured now by not one, but a few sources in the past considered professionals on the subject that when many speakers use a "Parallel" electrolytic cap across the woofer in a standard 2-way, 3-way etc... IN fact this is really not a highly critical spot to change because it will be the least effective in relation to sound, or performance?

So long story short I decided to rebuild a crossover using a cheap Electrolytic in this spot as suggested, and was originally installed. I don't know the ESR off hand, and listened. Interestingly enough being this was a rather large capacitance at 68 uF there was a sale on some Film caps I found a few weeks later only around 20 bucks for the pair vs. the 60 cent electrolytics I installed.

Beyond the fact these film equivalents were GIGANTIC in comparison, nearly half the size of a soda can vs. the little 1" Electrolytics, but I decided to jam them in there properly just to find out what would happen.

I do know the crossover cutoff point to these woofers was rather high around 600 hz. Yet this was a HUGE upgrade to bass output, and quality using the big film / shunt caps balancing out what seemed to be very compressed, and far less efficient sounding when using an electrolytic cap.

Now obviously the ESR was likely much lower using the Film, but is that the reason these speakers ended up sounding like serious reference quality depth in low frequencies vs. the Electro, or is it simply that most people even in the higher end manufacturers of this industry are living a myth that bass quality will not suffer from a 60 cent Electrolytic shunt style cap?

You tell me.

I can say no measurements were taken in this specific case, and it does not matter because the sound ended up far superior with zero downside effect at ridiculous high volume levels with balance I have heard out of few speakers in this class.

Just curious.


Jeff

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Re: How to deal with changed ESR?
« Reply #19 on: 29 Jul 2016, 03:01 am »
ESR has little to do with what you are experiencing.

Professionals do it for money, and hobbyist do it for fun....end of story :wink:

The use of electrolytics in the low-pass shunt is a budget and/or space constraint. 

Low-pass shunts are almost always the largest value in the XO, and the "least" egregious to position a electrolytic in.  That is not to say it is not egregious :wink: