How Long Do Vactrols Last....

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Bignorthumbrian
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How Long Do Vactrols Last....

Post by Bignorthumbrian » Tue Mar 26, 2019 1:37 am

I have a few modules that use vactrols, LxD, Optomix, 101-2, 2LPG and DPLPG.

What’s the average lifespan of a vactrol, and how do you know when it’s nearing the end of its life?
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Post by Gaetan » Tue Mar 26, 2019 2:45 am

From https://en.wikipedia.org/wiki/Resistive ... egradation
Irreversible degradation of a photoresistor can be induced by exceeding its maximum specified voltage even for a short period. For high-resistivity devices, this voltage is determined by the leakage currents flowing on the semiconductor surface and varies between 100 and 300 V for. For low-resistivity models, the voltage limit is lower and originates from the Joule heating.[58]

The service life of a RO is determined by the lifetime of the light source and the acceptable drift of the parameters of the photoresistor. A typical LED can operate for 10,000 hours, after which its parameters slightly degrade.[58] Its lifetime can be prolonged by limiting the controlling current to half of the maximum value.[40] ROs based on incandescent lamps typically fail after about 20,000 hours, due to the burnout of the spiral, and are more prone to overheating.[59]

Degradation of the photoresistor is gradual and irreversible. If the operating temperature does not exceed the limit (typically 75 °C or less) then for each year of continuous operation, the dark resistance falls by 10%; at higher temperature such changes can occur within minutes.[60] The maximum power dissipated in the photoresistor is usually specified for 25 °C and decreases by 2% for every °C of heating.[61]

Cooling below −25 °C sharply increases the response time of a photoresistor.[7] These changes are reversible unless the cooling induces cracking in the plastic components. Soviet ROs packed in metal cases could withstand even at −60 °C, but at these temperatures their response time reached 4 seconds.[62]
They should basically last for a very, very long time unless damaged. I don't really think it's something to be much worried about in our use of vactrols, especially with recent gear.

Does something makes you think your modules might not be working well ?

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Post by PM33AUD » Tue Mar 26, 2019 3:41 am

Interesting question (and very nice response too!)

As a designer, I worried more about their inherent 'sloppiness' in regards to part to part variation and some other parameters as well as the ability to get higher dynamic range using active components. Plus they are more expensive and many use cadmium (Cds in the R element), which isn't the friendliest substance to the earth (well, really, to the humans) but more immediately, it makes them non-compliant in terms of international regulations (I'm not currently up to date on the current exemption status but I think that ended a long time ago). To me, they are really good for isolation (hard to beat optical!) and linearity on the R side. But with the technology and cost of modern electronic components, they simply aren't needed in musical devices these days. Now let me find that chair icon... :hide:

There's some reading in here about the life effects as well as some plots over time.
http://denethor.wlu.ca/pc300/optoisolat ... uction.pdf

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Post by Skilling » Tue Mar 26, 2019 4:18 am

PM33AUD wrote: they simply aren't needed in musical devices these days.
:eek:

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Post by lilakmonoke » Tue Mar 26, 2019 4:36 am

the better question would be: how long do modules last anyways. i mean electrolytic capacitors definitely die before vactrols. so do cheap ass potentiometers and rack rash eats faceplates ;-)

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Post by cackland » Tue Mar 26, 2019 10:01 am

lilakmonoke wrote:the better question would be: how long do modules last anyways. i mean electrolytic capacitors definitely die before vactrols. so do cheap ass potentiometers and rack rash eats faceplates ;-)
Sounds like the zombies of eurorack

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Post by starthief » Tue Mar 26, 2019 10:45 am

cackland wrote:
lilakmonoke wrote:the better question would be: how long do modules last anyways. i mean electrolytic capacitors definitely die before vactrols. so do cheap ass potentiometers and rack rash eats faceplates ;-)
Sounds like the zombies of eurorack
This is what happens when you use bath salts to clean your synths :zombie:

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Post by addendum » Tue Mar 26, 2019 11:25 am

Capacitors and LEDs age differently. Optocouplers are based on an LED and a photocell that are housed in a light proof enclosure. As you probably know, the more an LED is used, the sooner it starts to dim - eventually, possibly after decades. If my memory serves, this applies both in terms of time and in terms of accumulated brightness over time, which in a VCF or LPG corresponds to output frequency and/ or amplitude.
I just found this, which claims that heat and rapid on/ off swicthing are additional factors: https://www.brandonindustries.com/blogs ... f-you-leds
So, other factors in a module aside, the lifespan of a vactrol based module seems to depend a) on how often and how long per session it's used and b) on the long-term accumulated brightness = filter frequency as well as the tempo of your CV changes that control the module, practically speaking.

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Post by cptnal » Tue Mar 26, 2019 3:09 pm

Vactrols last for precisely one million pings. No more, no less. :nod:

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Post by starthief » Tue Mar 26, 2019 3:25 pm

addendum wrote:So, other factors in a module aside, the lifespan of a vactrol based module seems to depend a) on how often and how long per session it's used and b) on the long-term accumulated brightness = filter frequency as well as the tempo of your CV changes that control the module, practically speaking.
I don't think an article about LED lamps for home lighting really applies very well here. We're talking about red miniature LEDs used in vactrols, not high brightness, white LED lamps that typically run for many consecutive hours every day.

Lowering your filter frequencies or playing at slower tempos isn't going to prolong their lifespan in any way that matters over someone who "recklessly" opens and closes an LPG fully at 240 BPM :lol:

I don't think I've ever seen a dead miniature LED. Capacitors for sure, and maybe some really old resistors, and chips fried by static or overheating or some idiot named me installing them backwards :doh:

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Post by Bignorthumbrian » Tue Mar 26, 2019 4:52 pm

Gaetan wrote:From https://en.wikipedia.org/wiki/Resistive ... egradation
Irreversible degradation of a photoresistor can be induced by exceeding its maximum specified voltage even for a short period. For high-resistivity devices, this voltage is determined by the leakage currents flowing on the semiconductor surface and varies between 100 and 300 V for. For low-resistivity models, the voltage limit is lower and originates from the Joule heating.[58]

The service life of a RO is determined by the lifetime of the light source and the acceptable drift of the parameters of the photoresistor. A typical LED can operate for 10,000 hours, after which its parameters slightly degrade.[58] Its lifetime can be prolonged by limiting the controlling current to half of the maximum value.[40] ROs based on incandescent lamps typically fail after about 20,000 hours, due to the burnout of the spiral, and are more prone to overheating.[59]

Degradation of the photoresistor is gradual and irreversible. If the operating temperature does not exceed the limit (typically 75 °C or less) then for each year of continuous operation, the dark resistance falls by 10%; at higher temperature such changes can occur within minutes.[60] The maximum power dissipated in the photoresistor is usually specified for 25 °C and decreases by 2% for every °C of heating.[61]

Cooling below −25 °C sharply increases the response time of a photoresistor.[7] These changes are reversible unless the cooling induces cracking in the plastic components. Soviet ROs packed in metal cases could withstand even at −60 °C, but at these temperatures their response time reached 4 seconds.[62]
They should basically last for a very, very long time unless damaged. I don't really think it's something to be much worried about in our use of vactrols, especially with recent gear.

Does something makes you think your modules might not be working well ?
Nope, they’re all working perfectly, I was just curious as I remember reading that they “wore out”
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Post by addendum » Tue Mar 26, 2019 5:50 pm

starthief wrote:
addendum wrote:So, other factors in a module aside, the lifespan of a vactrol based module seems to depend a) on how often and how long per session it's used and b) on the long-term accumulated brightness = filter frequency as well as the tempo of your CV changes that control the module, practically speaking.
I don't think an article about LED lamps for home lighting really applies very well here. We're talking about red miniature LEDs used in vactrols, not high brightness, white LED lamps that typically run for many consecutive hours every day.

Lowering your filter frequencies or playing at slower tempos isn't going to prolong their lifespan in any way that matters over someone who "recklessly" opens and closes an LPG fully at 240 BPM :lol:

I don't think I've ever seen a dead miniature LED. Capacitors for sure, and maybe some really old resistors, and chips fried by static or overheating or some idiot named me installing them backwards :doh:
If my Borg Filter sits unused with the frequency pot turned fully down 90 % of the time that my system is powered on, then the optocouple won't age, while other components slowly age as sooj as they 're powered on.
If the same filter fires from 0 to 10 volts at 240 bpm for two hours each day, the LED will dim eventually. Slightly. After a very long time.
I shouldn't have said "practically speaking", by which I meant to express the relevant factors in terms of practical use as opposed to technical terms. I didn't mean that you'll notice a difference after five years if you play minimal house instead of drum'n'bass.

And yes, you can see the difference between an aged and a a fresh LED. Not so much with red ones because they look relatively dark to our eyes, and neither with the fashionable blue ones because they blind our eyes, but in my modules with yellow LEDs, 15 years difference between two modules of the same type are visible as increasingly irregular surfaces. There are artificial colors like pink or approximations of violet where the chemical component making up the color changes over time. This doesn't apply to vactrols anymore, but yes, you can see "dead LEDs" or at least dying ones.

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Post by lilakmonoke » Tue Mar 26, 2019 9:28 pm

potentiometers are interesting in that respect, they seem to die if your are NOT using them. oxydation is responsible? i find all these thoughts frightening, i mean cwejman modules that cost $$ die just as fast as behringer modules for 49$ - just like vintage synths that have thousands of components that will crumble to dust at one point.

all this is one good argument for going full on digital eventually!

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Post by Shledge » Tue Mar 26, 2019 9:39 pm

Most components will last decades, easily. This includes vactrols.

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Post by WisdomWriter » Tue Mar 26, 2019 9:43 pm

this is an interesting question. I have pondered the life expectancy of modules and such. I figured if you take care of what youre using, and not just irresponsible with them, from my understanding they should last a loooooooooooooooooong time. I mean think of a Moog. those are lasting a long time.

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Post by slow_riot » Wed Mar 27, 2019 8:43 am

lilakmonoke wrote:potentiometers are interesting in that respect, they seem to die if your are NOT using them. oxydation is responsible? i find all these thoughts frightening, i mean cwejman modules that cost $$ die just as fast as behringer modules for 49$ - just like vintage synths that have thousands of components that will crumble to dust at one point.

all this is one good argument for going full on digital eventually!

.
It is a dangerous myth that all electronic devices are equally subject to degradation. Service life of any device is absolutely in the hands of the manufacturer, and therefore too, the consumer, because with a little research it's possible to discover the companies approach towards service lifetime, warranty repairs, etc.

Pots are rated for maximum number of rotations, which can vary from 10,000 to 1,000,000 . In some modules they can be replaced by the user without soldering.

I have had pots fail because of oxidation, but that was a rare case, and may have been related to a mistake in assembly by the manufacturer.

There are other aspects to design that can ensure high service lifetime, digital is often far worse than analog for this, because digital ICs are obsoleted much faster. Some analog ICs have stayed in production by multiple manufacturers for around 50 years.

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Post by lilakmonoke » Wed Mar 27, 2019 11:09 am

It is a dangerous myth that all electronic devices are equally subject to degradation.
from an engineering standpoint you are absolutely right. from an economical standpoint anything made after 1980 seems to have a built in self destruct mechanism and why should electronics be any different?

in my own experience i had the pots die in a cwejman s1 after 3 years and thats a 4k unit. on the other hand i have a yamaha cs-70m from 1979 that is made with thousands of discrete components and gazillions of point to point wires. the ageing components were drawing so much current that we had to replace all the PSUs in that synth but it was still working, kind of.

what im saying is that most of us who invest lots of $$ into analog gear dont think of these things but they are very real - and digital gear seems to be less affected because of the lower parts count - most simple casio synths from the 80s are still working perfectly.

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Post by Ears » Wed Mar 27, 2019 1:43 pm

I have lots of 70s electronics that I still use often. But maintenance is a reality. My early 70s mixer and my Jupiter 4 have been recapped . I’ve had to find replacement pots, batteries and lights. I’ve spend more on maintenance than on my initial purchase but with care these are reliable work horses. The biggest worry I see is where you get to older chips - these too can degrade and die and often it’s impossible to find replacements.

My newer electronics are more of a mixed bag. In many cases when they die it’s time to move on.

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Post by ersatzplanet » Wed Mar 27, 2019 2:14 pm

I guess you should checkout somebody or university that may have a Buchla from the bygone years that used Vactrols and ask them if they had to replace them yet.
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Post by dooj88 » Thu Mar 28, 2019 10:04 am

i swear i read somewhere that FPGAs had a limit of a million on/off cycles, but can't find it now to check.. some kind of logical limit?

the only way to hit that is power on/off multiple hundreds of times a day, but still, it's interesting.

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Post by lilakmonoke » Thu Mar 28, 2019 7:50 pm

i swear i read somewhere that FPGAs had a limit of a million on/off cycle
they run at a clock speed of 50 mhz so that would give them a live span of how many microseconds? ;-)

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Post by dooj88 » Fri Mar 29, 2019 9:41 am

lilakmonoke wrote:
i swear i read somewhere that FPGAs had a limit of a million on/off cycle
they run at a clock speed of 50 mhz so that would give them a live span of how many microseconds? ;-)
ah, i meant power cycles

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Post by slow_riot » Fri Mar 29, 2019 9:59 am

lilakmonoke wrote:
from an engineering standpoint you are absolutely right. from an economical standpoint anything made after 1980 seems to have a built in self destruct mechanism and why should electronics be any different?

in my own experience i had the pots die in a cwejman s1 after 3 years and thats a 4k unit. on the other hand i have a yamaha cs-70m from 1979 that is made with thousands of discrete components and gazillions of point to point wires. the ageing components were drawing so much current that we had to replace all the PSUs in that synth but it was still working, kind of.

what im saying is that most of us who invest lots of $$ into analog gear dont think of these things but they are very real - and digital gear seems to be less affected because of the lower parts count - most simple casio synths from the 80s are still working perfectly.
This is just as hard for a manufacturer to navigate.

Making device longevity a design principle is a risk that gives no economic benefit, because the market doesn't want it, people want convenience and so the industrialization of the technology builds itself around that i.e. high turnover.

It's also hard to market as a feature, because it's suicidal to make bold claims about reliability, and so you are forced to mention details that would only make sense to another engineer, such as user replaceable panel controls, socketed ICs, or industry standard parts.

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Post by lilakmonoke » Sun Mar 31, 2019 4:56 am

Making device longevity a design principle is a risk that gives no economic benefit
there you have it, exactly my point. btw. thats the reason why our times will go down in history as the garbage age that destroyed the planet. all that will be left of us is a toxic layer of plastic and throw away electronics. remember wall-e the movie?

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Post by slow_riot » Sun Mar 31, 2019 6:20 am

lilakmonoke wrote:
Making device longevity a design principle is a risk that gives no economic benefit
there you have it, exactly my point. btw. thats the reason why our times will go down in history as the garbage age that destroyed the planet. all that will be left of us is a toxic layer of plastic and throw away electronics. remember wall-e the movie?

Yesterday I started reading this:

https://en.wikipedia.org/wiki/Small_Is_Beautiful

E.F. Schumacher says that environmental costs should be considered as part of the economic costs, because they are borrowed from future generations.

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