40,000 uf without electrolyt?! - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 12, 2018, 08:52:40 pm
content: I have read an article about avoiding electrolyte condensators, but still have 40,000 uF.I have tried to simulate it, but I can't get any results, I understand.Will anyone please try to explain if it does work and maybe shot about how?http://s-audio.systems/diy/psu-without-electrolytic-eng

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 12, 2018, 09:03:18 pm
content: Gotta love audiophools, always willing to break something that's never been in need of fixing.The statement: "a low and stable impedance 0,1…0,2Ohm (equivalent to cap 40000u) in the band to megahertz" is meaningless (parsing the broken English as well as I can). A "stable" impedance, over any frequency range, is a resistance, not a capacitance. By definition (Kramers-Kronig relations).A typical 1000uF 25V electrolytic, for SMPS service, has maybe 50-100mohm ESR, beating this figure. An SMT part will have reasonably low ESL, beating the frequency range as well (say to 10s of MHz). And by "typical" I mean middling to cheap Chinese, say Capxon or Teapo brand.Do audiophools really buy electrolytic capacitors that are so bad, you need 40mF worth of them to get to a commodity-range ESR? I know they swoon over their wank brands like "Pureism", "Black Gate", "Silmic" and so on, but it's not hard to figure these things out. Well, if they went on measurement rather than belief, it wouldn't be hard...Tim

author: The Soulman
author_rank: Super Contributor
timestamp: March 12, 2018, 09:03:33 pm
content: Not sure what your question is here, but that site appears to be 95% nonsense.Yes electrolytic capacitors can degrade audio quality but only if used in the signal path (as dc blocking) without a healthybias voltage.In a power supply they are no problem and for a power amplifier, the more the better.

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 12, 2018, 09:13:44 pm
content: LOL yes snake oil and cryogenic frozen chicken wings in your lamps.-)My question is because EEV have talked about there instability and when I saw that article, I thought, hmm is that real?It is just to avoid the electrolytes' in a normal psu:-)

author: Buriedcode
author_rank: Super Contributor
timestamp: March 12, 2018, 09:47:28 pm
content: Quote from: FriedMule on March 12, 2018, 09:13:44 pmWhats is a "normal" PSU?

author: Brumby
author_rank: Unknown
timestamp: March 12, 2018, 09:58:32 pm
content: I'd start with a transformer, diode rectifier (pick a flavour) and some filter caps. Add a regulation circuit if you wish.

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 12, 2018, 10:50:51 pm
content: For a beginner, all psu's are standard:-)What I mean is that it was just a good start project and maybe it can later be used to burn down one of my later failures lol:-)But do any body know what it is?It delivers a fine sinus curve and that's about it, is it a "dirty electricity" filter?

author: Zero999
author_rank: Super Contributor
timestamp: March 12, 2018, 10:57:54 pm
content: Quote from: The Soulman on March 12, 2018, 09:03:33 pmYes, additionally for DC blocking, the AC signal voltage across the capacitor should be very low anyway, so there should be little potential for any distortion. The circuit would have to be very poorly designed for an electrolytic capacitor that size to create distortion.

author: TrickyNekro
author_rank: Frequent Contributor
timestamp: March 13, 2018, 02:47:22 am
content: Quote from: The Soulman on March 12, 2018, 09:03:33 pmWell isn´t that why you place them back-back?There are also non polarized electrolytics which are designed for audio and do exactly that

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: March 13, 2018, 07:55:22 am
content: Quote from: T3sl4co1l on March 12, 2018, 09:03:18 pmYou say that because you can't hear the difference!Jokes aside, more capacitance is not always better, but you need to understand some control theory for that. There is a reason why big linear bench supplies from the name brands don't have 40 mF on their output... Some won't even get in the few uF. They use feedback to regulate and don't need passive filters (which is what the electrolytics essentially are). The main advantage those passive filters can have is with regards to noise - feedback networks will still add noise, which capacitors filter out. But well, something about preaching and choirs.The schematic shown here just uses some feedback to get rid of capacitors. It doesn't "still have 40 000 uF". I guess it might behave similarly at low frequencies to a bridge rectifier with 40 000 uF attached to it?

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 13, 2018, 08:25:36 am
content: I am wary happy for your reply!Since I am new to all this, two of your answers do confuse me. :-)Quote from: blueskull on March 13, 2018, 02:54:35 amQuote from: TheUnnamedNewbie on March 13, 2018, 07:55:22 amCould it be funny to get EEV to answer this question?

author: 2N3055
author_rank: Super Contributor
timestamp: March 13, 2018, 08:33:37 am
content: Those two transistors right of the regulator are connected in such way that they will saturate, and vt2 and vt3 will start pulling all current the regulators are able to give, forcing them into current limit.The circuit doesn't even work, not to mention that circuit has no resemblance to what they are trying to explain as operating principle... There is no capacitance multiplier here, just shunting of output to ground...This looks like audiphool tried to create "A class power supply" ....He could just put shunt resistor on output.. LM317 inductive impedance varies with load, and some load on output is good , but if you load it with at least 50 mA ( with a simple resistor ) it's at minimum and stable throughout rest of range...Also for LM317 output , capacitors in 0.1uF to 20uF with very low ESR are BAD choice. They create high Q resonances that increase noise in audio range.. Recommended for lowest noise is at least 1uF on ADJ pin (4.7uF being good choice) and at least 50uF on output (100 uF plain vanilla electrolytic, and not the extra low ESR types)LM317 is an old design. There are many better ones now to chose from.If you want something better search for "Low-Noise Power For Analog Circuits - Walt Jung"It is a proper low noise design and not some "wo-wo"..Regards,Sinisa

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 13, 2018, 08:50:10 am
content: Quote from: TheUnnamedNewbie on March 13, 2018, 07:55:22 amFor some strange reason, I have this problem where, the more I pay for something, the more critical I am of it, and I can't open up and embrace the breadth and warmth of the soundstage, and......Or I just have tin ears.Tim

author: dmills
author_rank: Super Contributor
timestamp: March 13, 2018, 11:32:55 am
content: Quote from: 2N3055 on March 13, 2018, 08:33:37 amI am not seeing it, now I am not saying it is not a silly circuit, but I am not seeing a shorted output here, just a shunt reg working to maintain a constant voltage across R2 (And hence constant load on the LM317), VT1 is PNP!Regards, Dan.

author: 2N3055
author_rank: Super Contributor
timestamp: March 13, 2018, 12:04:14 pm
content: Quote from: dmills on March 13, 2018, 11:32:55 amHmm you are correct... My bad. Not enough coffee this morning...I know it's PNP, but I didn't think how it would behave with R2 value of 10 Ohms...And it will keep LM317 load at exactly same current all the time, at least until your PSU load exceeds shunt current... And that would definitely affect output impedance... It would be interesting to see how it behaves across frequency range...Regards,Sinisa

author: FriedMule
author_rank: Frequent Contributor
timestamp: March 13, 2018, 03:33:06 pm
content: Thanks for a great help!!As totally new, it is impossible to sort snake oil from reality!I will defiantly look at "Low-Noise Power For Analog Circuits - Walt Jung"As I understand it, this circuit I posted is at best, a good idea but bad made and properly without the intended result?

author: David Hess
author_rank: Super Contributor
timestamp: March 13, 2018, 08:15:59 pm
content: Quote from: FriedMule on March 12, 2018, 08:52:40 pmThey did all that work to fix something which was not broken and then kept the complementary 317/337 design with a split secondary transformer when a pair of 317s could have been used yielding more symmetrical performance.Some regulators do away with the bulk output capacitors and instead use a dampening network for performance reasons like fast response, fast current limiting, limited output energy, and perhaps high reliability but that was not done in this case. Their effort would be better spent on removing ground loops and improving the power supply rejection, decoupling, and bypassing in the audio amplifier itself.

author: shtoz
author_rank: Contributor
timestamp: March 14, 2018, 01:38:20 pm
content: http://s-audio.systems/diy/nazar-regulatorsimulation fileshttp://s-audio.systems/public/uploads/PSU/nazar-reg.ziphttp://designideas.cocolog-nifty.com/blog/2015/08/psu-for-high--1.htmlhttp://designideas.cocolog-nifty.com/blog/2015/08/psu-for-high--2.htmlhttp://designideas.cocolog-nifty.com/blog/2015/08/low-impedance-m.htmletcRegards,shtoz