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Capacitors

Printed From: Graham Slee at Hifi System Components
Category: DIY AUDIO
Forum Name: Graham's Wrinkles
Forum Description: My hints and tips on how to squeeze that little extra from an old
URL: https://www.hifisystemcomponents.com/forum/forum_posts.asp?TID=1037
Printed Date: 29 Oct 2020 at 8:27am
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com


Topic: Capacitors
Posted By: ServerBaboon
Subject: Capacitors
Date Posted: 01 Feb 2011 at 8:23pm

I have read this but I don't have the knowledge to comment but I will post here for interest of those that do.


http://www.tnt-audio.com/accessories/testing_capacitors_e.html - http://www.tnt-audio.com/accessories/testing_capacitors_e.html






Replies:
Posted By: Graham Slee
Date Posted: 01 Feb 2011 at 9:37pm
I quite liked this...

"Other valve afficionados swear by Hovland Musicaps, Jensen paper-in-oil, or Infinicaps (to name but 3 in favour on blogs) in the so called signal path and Cerafines or Black Gates in the power supply or cathode decoupling. There is no hegemony except that ridiculously expensive capacitors are believed essential in simple valve circuits to maintain any credibility among their peers. Fans of particular capacitor creeds do seem to express their views (especially on web forums) with a fervour that can only be described as religious. But, then they must justify the vast sums they have spent, like the emperor and his new clothes... or as the enlightened ones who we will eventually follow."

Wink


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Posted By: ServerBaboon
Date Posted: 04 Apr 2011 at 9:10pm

Here is the second part .


http://www.tnt-audio.com/accessories/cicada_caps_e.html - http://www.tnt-audio.com/accessories/cicada_caps_e.html



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Steve

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Various bits of GSP Kit ..well two so far, unless you count the cables that is.


Posted By: Graham Slee
Date Posted: 04 Apr 2011 at 11:02pm
"... a market that behaves like the art market ..."

That Mr Wheeler, he says it all you know Thumbs%20Up


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Posted By: tg
Date Posted: 05 Apr 2011 at 6:20am

Thanks for the link SB - am in the ongoing process of attempting to extract improvement from my amp by a process of study and replacement of selected components for various of the rather generic ones it was built with.

The process so far has yielded significant improvement at modest cost.

Reading his article suggested a couple of areas yet to be addressed and a cheaper alternative to another area already considered but not yet addressed.

Interestingly, to me, I have yet to see those particular caps on offer at any of the usual purveyors of boutique parts.





Posted By: daveyboyblue
Date Posted: 13 Jan 2012 at 2:44pm
Hi
 
I am no expert with electronics (far from it)...
 
I did however at a recent service have the caps in my ICON ST40 upgraded to jenson foil in oil and the difference in sound stage and added bass was amazing.
I am convinced that audio specific components do make a difference.
 
Cheers
Dave


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Rega P7 + TTPSU + 2M Bronze, Gram Amp 2 SE + Cusat50 + PSU1, Icon Audio Passive + Icon ST40 KT88. Naim CD 5 (Level 2 upgarade) + Flatcap 2 (22v upgrade. Clic M1. AE AElight, Atacama Rack


Posted By: Graham Slee
Date Posted: 13 Jan 2012 at 3:55pm
Originally posted by daveyboyblue daveyboyblue wrote:

Hi
 
I am no expert with electronics (far from it)...
 
I did however at a recent service have the caps in my ICON ST40 upgraded to jenson foil in oil and the difference in sound stage and added bass was amazing.
I am convinced that audio specific components do make a difference.
 
Cheers
Dave


Some do... Wink


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Posted By: suede
Date Posted: 13 Jan 2012 at 5:16pm
Has anyone here tried using flux capacitors? Wink


Posted By: mrarroyo
Date Posted: 13 Jan 2012 at 8:53pm
Originally posted by suede suede wrote:

Has anyone here tried using flux capacitors? Wink

With or Without upgraded parts? Yes, I am evil.


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Miguel


Posted By: Graham Slee
Date Posted: 15 Jan 2012 at 9:39am
Originally posted by mrarroyo mrarroyo wrote:

Originally posted by suede suede wrote:

Has anyone here tried using flux capacitors? Wink

With or Without upgraded parts? Yes, I am evil.


Honest maybe, but not evil.

When trying "audio specific" parts such as capacitors I have found it best to reserve judgment until many weeks have elapsed.

A capacitor is much more a chemical process than other components (although they too often need as much burn-in). A capacitor shares similarities with a battery -- especially the electrolytic variety -- they have a life-span marked out for them and you really need to understand that and pitch the performance for their stable years.

I have tried numerous audio grade capacitors and they all place their own signature on the music. For example, Silmics are great at first but then turn brittle in upper registers and wash out all the emotion.

I have found by delving deeper into the "mechanics" of a circuit and pulling the devil out of the detail -- even the little dregs -- has a far better effect than an audio specific device.




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Posted By: suede
Date Posted: 15 Jan 2012 at 1:31pm
I'm sorry, it was a film trivia joke from the 1985 movie Back To The Future, in which they travel in time with the help of a "flux capacitor". Some truly magical capacitor there at least. I don't know if the word can actually mean something intelligable in the real world, if so that's not what I meant Confused


Posted By: Graham Slee
Date Posted: 15 Jan 2012 at 4:51pm
Yeah, flux capacitor! Time travel. Great idea but too complicated to ever work, even if there is such a thing as a flux capacitor...

I wonder if Jensen may make one? Maybe we can modify a Blackgate or a Silmic...

Sorry all, I don't believe in audio grade components any more, or father christmas, or easter bunnies.... it's all an excuse for they to have more of your money than you do.


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Posted By: discrete badger
Date Posted: 15 Jan 2012 at 4:59pm
If electrolytics have a finite lifespan, then wouldn't one expect simply renewing like-for-like with fresh parts, where they have driffted from spec, to improve the sound drastically? 

Once, whilst looking for something else I found a posting of one enthusiast who, despite liking the sound of an amplifier he owned, had opened it up and found an op-amp inside which some think is bad-sounding and therefore he felt he had to replace it immediately. Until someone else pointed out that the op-amp was doing some ancillary control function and was not actually in the signal path.....


Posted By: Graham Slee
Date Posted: 15 Jan 2012 at 8:15pm
1] Life time of an electrolytic is at rated temperature. General purpose and some "audio grade" types are 85 degrees celsius. That is very hot! The capacitor will last 1,000 hours or about 6 weeks before the fluid (which incidentally isn't the dielectric or insulator -- the anodising is that) which moistens the separating paper dries out completely. In use at ambient earth temperatures the life time can exceed 20 years.

2] I like that one! That is why we scrub off part numbers or encapsulate them. I had noticed so many great op-amps being discontinued thanks to forum land thickies and a certain retired gentleman called Bob "don't use anything but my own designed op-amp" of a now non-existent company snaffled up by TI who doesn't have a care for keeping the said companies products in circulation. So we bought all those great op-amps which became after that moment obsolete. You'll find a few thousand people raving about those op-amps without realising it. They are our customers...

I should add, it does help if the designer actually knows how to use them.


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Posted By: discrete badger
Date Posted: 16 Jan 2012 at 6:40am
Understood about the 20 year spec thing, but this does seem to be an issue with beefy power amps for a few reasons: the electrolytics in the power supplies can be pushed quite hard due to high idle power consumption and raised internal temperatures, and there is quite a lot of "heavy iron" investment in the large transfromers and heavy casework which means less of a temptation to sling it in the bin when the electrolytics have dried out early.

My two power amps (same model, but not very beefy at all and low idle power) are approaching 15 years old, and the one which has never been serviced is showing a bulge on 2 of the 4 power supply caps, corresponding to the right channel. Still sounds as good as the left channel at the moment. The point I guess I'm making is that with well designed equipment that the owner still gets a lot of pleasure out of, 20 years might not be such a long time.


Posted By: jrhughes
Date Posted: 29 Apr 2012 at 10:22pm
I'm learning so much here. Started to do some reading around following a very informative post by Graham in the "burn-in" thread, where, finally, I am understanding about anodising slit edges... anyway, looking up some details about electrolytic capacitors I saw lifetimes mentioned in hours and was terrified! Thank goodness it's more like 20 years.

Assuming there are electrolytic caps in the PSU1, does the warmth in that equate to much of a lowering of lifetime?


Posted By: Graham Slee
Date Posted: 30 Apr 2012 at 6:06am
Originally posted by jrhughes jrhughes wrote:

I'm learning so much here. Started to do some reading around following a very informative post by Graham in the "burn-in" thread, where, finally, I am understanding about anodising slit edges... anyway, looking up some details about electrolytic capacitors I saw lifetimes mentioned in hours and was terrified! Thank goodness it's more like 20 years.

Assuming there are electrolytic caps in the PSU1, does the warmth in that equate to much of a lowering of lifetime?


Capacitor manufacturers play their cards close to their chests so to speak - they declare what they want to declare.

Having said that, comparing a lower temperature range (85 degrees C) the endurance at 40 degrees C is 7 years. The caps in the PSU1 are 105 degrees C so they should run warmer for the same endurance. As temperature falls capacitor endurance increases considerably. The endurance or lifetime is quoted for the capacitor working to specification. After that time it will still be working although it may have started to drift away from its specified performance.


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Posted By: jrhughes
Date Posted: 30 Apr 2012 at 11:24am
Thanks Graham - you've answered my next question already: I had been wondering if the lifetime of the caps in the Solo were, say, 20 years, whether it would stop working in 20 years or just perhaps start to sound different. 

Is the sonic effect of caps which have started to drift easy to spot, or so gradual that it's unlikely to be noticed until the whole thing just stops working? I'm thinking of my new Solo/PSU1 and also, potentially soon, a Reflex. Also, thinking about it, my Cyrus stuff is fifteen years old now (Cyrus 3 + PSX-R and dAD3Q + PSX-R)...

Edit: sorry if I'm hijacking a thread... let me know if I should move to a new one.


Posted By: Fatmangolf
Date Posted: 30 Apr 2012 at 8:43pm
Very informative and helpful thread. Thumbs Up

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Jon

Open mind and ears, whilst owning GSP Genera, Accession, Elevator EXP, Solo ULDE, Proprius amps, Cusat50 cables, Lautus digital cable, Spatia cables and links, and a Majestic DAC.


Posted By: DogBox
Date Posted: 19 Mar 2019 at 2:13am
Please Direct Me! 
I thought Here would be a good place to find "Bypassing" with Film Capacitors... but no-one seems to have mentioned it (besides Graham in the Genera notes.)... When I made my crossover for my JBL's it was a suggested thing to do... Costly little things! especially when you buy 10 and realize it wasn't enough to do both channels in 0.01uF AudioCap's from Parts Express in the USA and you're in Oz... 
 I had no idea "bypassing" could be beneficial in other instances too..? I live and learn again!! What a site!! Beats encyclopedia's!! Wink 


Posted By: Graham Slee
Date Posted: 19 Mar 2019 at 5:46am
The bypass capacitor could have been yet another Walt Jung idea from his 70s/80s quests for higher fidelity in the US Audio magazine. Then again, it might have been used by RF engineers prior to that (the latter seems more obvious).

It can be a cure or it can be a con.

Adding 0.01uF to a crossover capacitor that's say 0.22uF might be heard as a difference in tone, especially knowing that speaker drive units can resonate all over the place, and if the addition just happens to be in the right/wrong place...

Hi-fi is an opportunist’s paradise so proceed with care.

Remember, a capacitor is also a resistor and inductor; a resistor is also an inductor and capacitor; and an inductor is also a resistor and a capacitor. These are secondary functions known as parasitics, not intended but there because nothing's perfect.

Parasitics can sometimes be benign, and at other times a complete bastard - a destroyer of faith in one's own abilities. I will only discuss the effects in an active electronic circuit here.

Bypassing an electrolytic capacitor with a film cap can often make an amplifier circuit sound different. That difference can be better, or worse in the way it sounds, or measures.

An electrolytic supply decoupling cap can let higher frequencies run amok in high frequency sensitive circuits. This is because it has series inductance (it also has series resistance which we'll come to). At HF the inductance adds resistance which reduces the caps "grip" on supply "stiffness". Placing a 0.1uF film across it is often the cure, as it offers some energy storage at HF, bringing supply "stiffness" back.

But it can also lead to glitches which can upset HF performance. Here you'd draw on paper the electrolytic's circuit which is the capacitor sign in series with an inductor sign in series with a resistor sign; and then you'd draw the film cap in parallel with it, but the film cap also has inductance and resistance, so you'd draw them as well.

Then you need to draw in the values. You know the capacitance but you need an awful lot of information about the components to draw in the inductive and resistive values. Such info should be available from capacitor manufacturers, but it mostly isn't. It's much easier for them to tell you the price...

A good guess for the electrolytic is 0.05 ohms and 50 nH inductance; and for the film cap: 0.005 ohms and 5 nH.

Then all you have to do is use all the LCR formulas you ever knew, or have to learn, to pull out the different excitation frequencies.

Oh, and one more thing: you also have to know the supply series impedance and the load's parallel impedance, to see what effect they have.

Much easier to do a simulation schematic and let the computer do you a frequency plot. Try these folks: https://www.simetrix.co.uk/ - https://www.simetrix.co.uk/

Armed with the above you can now turn your attention to the bias cap in the Genera (C9). It doesn't have a bypass, but can it? What does that voltage do? It is the reference voltage against which the op-amp decides what it's doing with the signal.

At high frequencies the PSSR (power supply noise regulation) diminishes, but as it's a resistive split it would only be -6dB to start with. The electrolytic makes it much much better, but can you figure out where it's going at really high frequencies? At some point that reference can be getting a little sloppy.

Once you have your Genera built and run-in a few weeks, tag a 0.1 - 1.0 uF film cap across C9 (under the board) and tell us what you found? Give it a week to bed-in though.

What type of film cap? Something like this should do nicely: https://uk.rs-online.com/web/p/polyester-film-capacitors/1262268/ - https://uk.rs-online.com/web/p/polyester-film-capacitors/1262268/

And don't buy "boutique"!


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Posted By: DogBox
Date Posted: 19 Mar 2019 at 11:06am
Graham said: "And don't buy "boutique"!" 

Thanks for that! Boutique MKT caps??   The ones I got were  https://www.parts-express.com/audiocap-ppt-theta-001uf-600v-film-foil-capacitor--027-700 - https://www.parts-express.com/audiocap-ppt-theta-001uf-600v-film-foil-capacitor--027-700 ...Yep! Boutique alright! Now you might also realize why I copped out at ten of 'em! Was cheaper at the time than the alternative! 
[you're gonna love this!] Charge - coupled - crossover - network. Heard of it? Basically, for every capacitor in the crossover, you double its capacitance and use two of them in series and put a 9vDC charge at the series join. eg.   http://www.audioheritage.org/vbulletin/showthread.php?39310-Giskard-Charge-coupled-3145-crossover-network-iron-core-inductor-source - http://www.audioheritage.org/vbulletin/showthread.php?39310-Giskard-Charge-coupled-3145-crossover-network-iron-core-inductor-source This was pretty much the circuit I followed for my 4343 albeit some drivers and such were different. Very interesting idea that, when implemented properly, gives outstanding results. I have never personally heard the results but JBL certainly benefitted from the design. Also only giving it to their top models. Look for the battery case near the speaker terminals. With the price of some of the best capacitors being used and doubling the quantity + higher capacitance capacitors... Cost a bundle! Too much for me! I used to read and re-read those posts trying to get my head around what was going on whilst also studying another completely different subject and both let me absorb little of each subject. 
 Which also brings me back to C9 and also those two 56k resistors. I do remember you going into great detail in the Phono Preamp Project now out to 55 pages! and worth every bit! I still haven't got through it.. Looking after my mum eats up plenty of my hobby time... but you've only got one mum and mine has been cursed with Parkinson's in her later years and i'm it as far as hired help to look after her. Well, besides the ones who come in to clean and take care of the garden. So, progress on my Genera is slow at present but at least we have organized all the parts to some semblence of order!  And my speakers do sound rather nice! So I am at this keyboard or I can swivel around 180° and start soldering. Then again I don't want to wake anybody up seeing it is also that time of night for me on this side of the moon... and my block of chocolate has run out! Damn! Have to go and continue tomorrow.  


Posted By: Graham Slee
Date Posted: 20 Mar 2019 at 8:39am
An electrolytic capacitor is called what it is because charge "travels" one way (actually it can be made to flow the other way if you want to destroy it). It is similar in some respects to electroplating, anodising, and the way a wet-plate battery works: these too have polarity.

An audio signal doesn't add to that charge because it is AC, and a positive excursion cancels a negative excursion and vice-versa, and in fact, if we make time constants such that they are larger than any expected in sound repro, the AC "travels" on top of the DC voltage charge. This is how coupling is done.

But here we have large capacitors used as filters, to attenuate parts of the signal spectrum. I can't be sure but in other circuits non-polar electrolytics might be used. These are basically two back to back electrolytics of twice the required value connected in series, in one package.

We should not apply DC to these, because the section with the opposite polarity is reverse charged, which will destroy it. So perhaps we assume here that they are not electrolytics of any type?

Here we see some capacitors being charged to 9V over a long period (via 3 megohm resistors): some taking upwards of 30 minutes to reach 60%, then another 30 minutes to reach 60% of what's left, etc.

If back to back electrolytics there will be considerable initial leakage, as all electrolytics have leakage. Leakage is where the capacitor charge rate doesn't obey the rules, and is like having the current bypassing the capacitor by some imaginary resistor. If these were regular electrolytics I doubt if they'd ever reach charge because the 3 megohm resistors would limit charge current well below leakage current.

Anyway, what purpose does this serve? In my opinion it will be to fanny about with the sound, that's if it's audible, and if it is, to what advantage? My own opinion on this branch to hi-fi is, 1. it's a misuse of components and therefore is environmentally unfriendly; 2. the people who think it's an improvement must be in need of better equipment to start with (might have paid a ton of money for under-performing products) and are clutching at any straw offered to them. 3. It is just my own personal opinion, but it's a way of making money by clever marketing designed to disguise the ignorance of whoever came up with the idea. In other words, there is no difference between its promoter and a snake-oil peddler.


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Posted By: DogBox
Date Posted: 22 Mar 2019 at 10:19am
Ah, my friend Graham, 
It is Metallized  Polypropylene that are used in speaker crossover networks and because they are "Passive" in their operation, the using of just resistors and capacitors as in a RIAA curve won't do, we are trying to mess with the frequency response when you try and 'smooth' the transition of one speaker and its phase and response with the next speaker to handle the set of frequencies you are hoping for! Yes, some have even called it a Black Art - some others have enough money and the computer simulation program to help you along and take out some of the guess work (or, get out the calculator to help with some of the formulas to work it out in a Linkwitz-Riley format or some of the others!) 
 It is a land of Analogue that some find themselves travelling if they desire to build a set of speakers that sound half decent. Maybe that's my problem..(although I have had others spell it out plainly before today!) I put my interests into too many different fields of Hi-Fi to be any good at just one of them... Keeps me amused and on this side of the turf where daisies grow.. Otherwise I would have thrown in the towel ages ago. Chronic pain has its downsides and the black dog always wants to keep you company... 
 Instead of capacitors, I found out about Foil Resistors and how they lack "noise" in a circuit. Not surprising they have a cost out of this guys pockets! $18 ~ $55 each is what you do to have a "silent circuit!" Wow! Multiply that to only the necessary signal path - you still need 15 to 20 odd resistors, don't you? Apparently the difference IS audible quite easily - no snake oil here... 
 I have a Genera to build. and I am using the parts I bought. I am sure that for now I will be very happy with my finished article! No snake oil in there either! Clap Cool 
Kind Regards,
DogBox [Steve]    


Posted By: DogBox
Date Posted: 22 Mar 2019 at 10:22am
Oops! forgot the link:  https://solen.ca/product-category/capacitors/fast-capacitors-400v-pb-series-metallized-polypropylene/ - https://solen.ca/product-category/capacitors/fast-capacitors-400v-pb-series-metallized-polypropylene/ There ARE more expensive and better ones, but this line does me! 

DogBox


Posted By: Graham Slee
Date Posted: 22 Mar 2019 at 10:45am
I'm very happy that I'm not into speakers.


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Posted By: Graham Slee
Date Posted: 22 Mar 2019 at 10:52am
I do use speakers however, to test what our products do. They are Stirling LS35A and Harbeth M20, because this is the sound I am used to, having done a few years exposed to broadcast and studio sound. Incidentally, it is the sort of sound I have heard also in professionally equipped venues, such as the one owned by John Barry's mam and dad...


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Posted By: Ash
Date Posted: 22 Mar 2019 at 1:42pm
Graham, have a look at the Mark Audio Alpair 11 MS (mono-suspension) driver. In a suitable enclosure, it should be a decent single driver per channel emitter. No crossovers needed. I know you have your doubts with regard to things like intermodulation distortion but no speaker system is perfect. There is an Alpair 7 MS as well, which you might prefer?? After selling a bit more of my hifi equipment, I'm going to get a pair of 11MS to try, which I suspect will be better than my MySphere 3.1 in some ways, for considerably less cost.


Posted By: Graham Slee
Date Posted: 22 Mar 2019 at 2:56pm
Thank you for your suggestion but I need the references which fit my hearing; room etc, and without them I would not have been able to develop the products that you currently enjoy. This is not a dig.


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Posted By: DogBox
Date Posted: 28 Mar 2019 at 3:57am
Back on page 3:  Once you have your Genera built and run-in a few weeks, tag a 0.1 - 1.0 uF film cap across C9 (under the board) and tell us what you found? Give it a week to bed-in though. 

Graham, should (per the Genera Phono Preamp Part 1:) a definite change be audible where "The op-amp reference voltage is set by a simple resistor potential divider R11 and R12, and bias current is provided by R2, with a capacitor C9 to ground which provides power supply noise rejection for the inputs...a large value to prevent 'motor-boating' - the power supply could cause oscillation by feeding back into the inputs."  

So the 'biasing capacitor' under the board should make the 'circuit noise' even quieter?  

Also, from page 2 of the Phono Preamp Project forum you put up a Simplified Active RIAA filter courtesy of Walt Jung and I looked at the filter and how it was structured with R1 then C1 and R2 in series paralleled over R1 and further C2 paralleled over R2... 
 Are there different ways of doing this but a way that is arranged such that the phase and filter will work together and not compete and throw the other out? 

I am sure you will tell me how far wrong I am but please... be gentle. 

My copy of The Art Of Elect. came - Hardcover and weighing in at 10 pounds!...well, it IS heavy!  
So very grateful for your Help! 
[I'll get to the MC side of things next...!] 
Grateful, 
DogBox 



Posted By: Graham Slee
Date Posted: 28 Mar 2019 at 11:14am
1. It is more about unintended signal feedback and its effect on the sound. The image on this page may help? https://www.murata.com/en-eu/products/emiconfun/capacitor/2013/02/14/en-20130214-p2 - https://www.murata.com/en-eu/products/emiconfun/capacitor/2013/02/14/en-20130214-p2

2. There are a number of "best fit" equations for obtaining the "right" curve, as well as a number of configurations which essentially achieve the same thing. But having tried just about all of them in my lifetime (so far), my hearing tells me they all have subtle differences, and I have chosen the configuration which suited my hearing best.

When using the "best fit" equations we soon find that at some gains they don't fit at all, but in mathematical modelling domains are taught (which illustrates this fact), and so if you look at some switched-gain (MM/MC) circuits you will notice the apparent lack of education!



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Posted By: Graham Slee
Date Posted: 28 Mar 2019 at 4:21pm
You might also wish to read the article by J.L. LINSLEY HOOD starting on page 261 (page 57 in Acrobat viewer) https://www.americanradiohistory.com/Archive-Wireless-World/80s/Wireless-World-1989-03.pdf

It also gives us a clue as to why the liberal use of little red Wima polypropylene capacitors in high-end products might not lead to the expected results... Shocked

He should know his stuff (that should be past tense as he died in 2004) having been an engineer in "plastic films".


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