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Capacitors

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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post 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 ...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 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.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post 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.
Not simple enough for Google-Bot to understand...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post 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]    
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DogBox Quote  Post ReplyReply Direct Link To This Post Posted: 22 Mar 2019 at 10:22am
Oops! forgot the link: 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! 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 22 Mar 2019 at 10:45am
I'm very happy that I'm not into speakers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ash Quote  Post ReplyReply Direct Link To This Post 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.
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