View Full Version : Quite Interesting....
Arkless Electronics
27-10-2016, 17:47
It has long been known that electrolytic capacitor ESR can be temperature variable. Chemical reactions slow down with reducing temperature.
I had heard anecdotal evidence of radio equipment in Arctic expeditions needing to be warmed before use but at those temperatures it's not exactly surprising...
I'd never come across this phenomena in practice till today though.
I won't bore you with the exact experiments I was doing and why this parameter was unusually critical but needless to say a circuit which worked great yesterday didn't today... nothing had been touched since it worked yesterday. The only difference was I had the heating on yesterday!
Knowing ESR was vastly more important than usual in this circuit, I took an identical capacitor and connected it to my ESR meter. It had about twice the ESR of the identical one I had fitted after testing its ESR yesterday! I got my trusty workbench hair-dryer out and heated it up whilst watching the ESR meter... It soon went down to the same as yesterday and then as I kept the heat on to half again!
I directed the dryer at the actual piece of circuitry and heated it a bit then tried it again... working perfectly!
Now, it only took me a few minutes to make the changes to my circuitry to ensure temperature was now irrelevant, so why do I mention it?
Think of the implications re equipment warm up from stone cold and for differences you may have heard depending on whether the heating was on or not;) Well I thought it Quite Interesting anyway:D
Ali Tait
27-10-2016, 18:23
'Tis indeed, not something you'd think would have such an effect at room temperatures.
Arkless Electronics
27-10-2016, 18:41
Indeed it is not Ali. The use to which this particular cap was being put was extreme as far as ESR issues actually making it stop working (and was easily fixed) but that it illustrates 50% or so change with the difference between a cold house and one with the CH on certainly surprised me! This must be causing real differences as equipment heats up;)
Maybe one of the reasons why all preamplifiers are left on 24/7, as well as the CD player being left in 'standby' mo (the electronics left on, except the laser).
walpurgis
27-10-2016, 20:04
I leave nothing on once I've finished listening. For me it just 'goes against the grain' thinking wise to do so.
I appreciate that most of my gear takes a while to warm up and 'come on song', as it were. But I don't mind that. In fact it always gives me a pleasant surprise when the sound snaps into focus after about ten or fifteen minutes and continues improving for up to an hour or so.
paulf-2007
27-10-2016, 20:16
I leave nothing on once I've finished listening. For me it just 'goes against the grain' thinking wise to do so.
I appreciate that most of my gear takes a while to warm up and 'come on song', as it were. But I don't mind that. In fact it always gives me a pleasant surprise when the sound snaps into focus after about ten or fifteen minutes and continues improving for up to an hour or so.same for me, my garden room gets very cold so I put the kit and heating on and leave it running for a while mid winter, before listening.
Arkless Electronics
28-10-2016, 16:31
Unbelievable response.... but not surprising any more :eek: A real phenomena, which can effect the sound, and to the best of my knowledge hasn't been reported within the annals of hi-fi before... hmmmm Maybe if it was something really tenuous, probably non existent, and formed from purest foo we would be up to page 5 in the discussion by now:rolleyes:
:sofa:
Has it caused you to revise your opinion that the text books on audio technology are complete and there are no new discoveries to be made?
Probable inadvertent even ? reason why some fit only Film n Foils to a circuit, or at least any bit that has signal.
Arkless Electronics
28-10-2016, 16:55
Has it caused you to revise your opinion that the text books on audio technology are complete and there are no new discoveries to be made?
As I've never held that belief it would be impossible for it to be changed..... I believe you are referring to my saying that certain things which are not in text books, for very good reasons, definitely don't have any effect. On that I am 100% sure.
Arkless Electronics
28-10-2016, 16:56
Probable inadvertent even ? reason why some fit only Film n Foils to a circuit, or at least any bit that has signal.
Ever tried finding (let alone fitting) a 1000uF film cap?
Arkless Electronics
28-10-2016, 17:02
The effect is even mentioned in some capacitor data sheets etc so it's not unknown. The point is that the degree of change, even from just a cold room to one with the heating on, is quite marked. and much more so than I had imagined. Enough for some audible changes to be attributed directly to this phenomena when discussing warm up effects, or difference in sound on different days (when there are different temps!).
paulf-2007
28-10-2016, 17:24
My PX25 mono's built by Jim Turner take an hour to sound their best and it's more noticeable with lowthers. To start they sound thin and distorted.
Ever tried finding (let alone fitting) a 1000uF film cap?
The expected response. You are absolutely right of course.
Likely why god gave us Bypass caps ?
Are there likely to be electrolytic caps in my speakers and if so would these be affected by the phenomenon you have investigated regarding ESR?
Arkless Electronics
28-10-2016, 19:02
Are there likely to be electrolytic caps in my speakers and if so would these be affected by the phenomenon you have investigated regarding ESR?
Very good point James! Yes and yes! Most speakers have bipolar electrolytics in them...
StanleyB
28-10-2016, 19:30
I directed the dryer at the actual piece of circuitry and heated it a bit then tried it again... working perfectly!
Repair technicians and audio engineers have been using that technique for decades to find faulty caps, and improve signal stability.
Arkless Electronics
28-10-2016, 20:03
Repair technicians and audio engineers have been using that technique for decades to find faulty caps, and improve signal stability.
No shit Sherlock!? The point is that even in brand new 100% working electrolytic caps one of the main characteristics of the cap can vary by as much as 50% with normal variations in room temperature.
Anyway the phrase "pearls on swine" leaps to mind and I'm off to see a band:D
sq225917
28-10-2016, 20:11
Organic polymer, better temp stability. Shame they only come in modest sizes, up to a couple of 1000uf max.
No shit Sherlock!? The point is that even in brand new 100% working electrolytic caps one of the main characteristics of the cap can vary by as much as 50% with normal variations in room temperature.
Anyway the phrase "pearls on swine" leaps to mind and I'm off to see a band:D
Sarcasm will get you nowhere - you are not the only designer of audio gear here on AoS.
Firebottle
28-10-2016, 20:51
Are there likely to be electrolytic caps in my speakers and if so would these be affected by the phenomenon you have investigated regarding ESR?
Have no fear James, your speakers only have foil caps in :)
CornishPasty
28-10-2016, 22:49
Unbelievable response.... but not surprising any more :eek: A real phenomena, which can effect the sound, and to the best of my knowledge hasn't been reported within the annals of hi-fi before... hmmmm Maybe if it was something really tenuous, probably non existent, and formed from purest foo we would be up to page 5 in the discussion by now:rolleyes:
:sofa:
This is AoS, not PFM!
walpurgis
28-10-2016, 23:00
This is AoS, not PFM!
Oh my god! That can't be right. Are you sure? To think, all these years and I've been posting on the wrong forum! :eek: ;)
Arkless Electronics
28-10-2016, 23:39
Organic polymer, better temp stability. Shame they only come in modest sizes, up to a couple of 1000uf max.
The cap in question is a 10uF 350V Panasonic standard (not low ESR or anything) electrolytic. ESR is about 10R when cold (8C ish) and drops to about 3R when about 25C. There are many applications where as long as it's at least 100R it ain't going to matter... but there are several more where this will make a measurable change to the performance, and I'm sure also an audible one. Life is too short, and I've got better things to do, than to start measuring the ESR of all sorts of caps V temp..... maybe this brand and value/voltage rating is unusually prone to it... Like I say I for one found it quite interesting in that it could explain quite a few aspects of changing sound with warm up and at different temperatures.... if only in amps (or other things. CD players, DACS.. you name it..) that utilise electrolytic caps in a manner where ESR can cause real effects. I would guestimate around of half of all equipment could be effected.
If anyone wants to investigate further, I suggest a first order passive integrator of 4.7R and 10uF, fed from a suitably low impedance source, at around 3-6KHz and a few volts. Monitor the output across the cap whilst heating and cooling the cap;)
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