Topic: Bypass capacitors in the power supply

[qguy]

Been reading (understanding is another thing) on Bypass capacitors in the power supply section of an amplifier. Anyone done this here and what were the effect

[shrek7]

Been reading (understanding is another thing) on Bypass capacitors in the power supply section of an amplifier. Anyone done this here and what were the effect

naku, parang san mig light!

Mahaba habang usapan to!

Tried this with different capacitors, different values, different amps with different results. May computation kasi ang value ng bypass caps based sa cap na i-bypass mo. One of the high end stores technician here in cebu advocates doing that. Bypassing electrolytic power caps by an oil cap (obligatto oil caps) he said this is for cleaner power supply. Syempre, technically di ko ma explain. Ive tried using mang gerrys oil cap with good result. Also tried mcaps, good result din.
Paging sir mel. Paano ba tlaga ang computation nito? Sq observation, cleaner highs, more defined lows.

[ATJr.]

no, i never used them on my tube amps and i never seem to miss them.......there was a time when bypass on the psu was a big deal.....times have changed and thinking likewise changed .....there is an interesting thread here: http://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size.html
http://www.diyaudio.com/forums/power-supplies/106648-paralleling-film-caps-electrolytic-caps.html
http://www.diyaudio.com/forums/parts/212563-power-supply-capacitors.html

but you are welcome to try......and find out for yourself...; 

[shrek7]

no, i never used them on my tube amps and i never seem to miss them.......there was a time when bypass on the psu was a big deal.....times have changed and thinking likewise changed .....

but you are welcome to try......and find out for yourself...

+1   

sound varies depending on the material of the bypass caps. Polypropelene cleans the sound, but most of the time, its way to clean, with irritating highs. Trying this is like cooking kare kare for the first time, malaki ang chance na palpak! Unless may master chef ka na kasama. It will all depend sa panlasa mo, kaso minsan, since ikaw ang nagluto, di mo.minsan makain kasi naumay kana. Sori, mali yata ang comparison ko.

[qguy]

oopps.. my bad,  the application is for a Solid State amp, iba ba ang effect ng bypass on SS vs Tube amp ?

no, i never used them on my tube amps and i never seem to miss them.......there was a time when bypass on the psu was a big deal.....times have changed and thinking likewise changed .....there is an interesting thread here: http://www.diyaudio.com/forums/power-supplies/216409-power-supply-resevoir-size.html
http://www.diyaudio.com/forums/power-supplies/106648-paralleling-film-caps-electrolytic-caps.html
http://www.diyaudio.com/forums/parts/212563-power-supply-capacitors.html

but you are welcome to try......and find out for yourself...;  

[ATJr.]

even for ss amps.....those threads will give you good insights....

[qguy]

How can I go wrong   Ang dami kong master chef na kasama sa Internet 

+1   

sound varies depending on the material of the bypass caps. Polypropelene cleans the sound, but most of the time, its way to clean, with irritating highs. Trying this is like cooking kare kare for the first time, malaki ang chance na palpak! Unless may master chef ka na kasama. It will all depend sa panlasa mo, kaso minsan, since ikaw ang nagluto, di mo.minsan makain kasi naumay kana. Sori, mali yata ang comparison ko.

[shrek7]

How can I go wrong   Ang dami kong master chef na kasama sa Internet 

hehehehe!!! Nice!  ive actually tried it on ss and tube amps, and as I always say it depends sa panlasa mo, there will always be a some sort of trade off, like an amp with warm sound and less detail may gain higher resolution, greater details loosing its warmth and may add sibilance, so para talaga itong cooking, you should try different spices. (different types of caps)

[markcrenz]

I use small bypass caps. no i don't expect the bass to shape shift, the midrange to become a liquid or the treble to be sifted of pebbles. just to improve psu impedance and prevent oscillation.  

[rascal101]

I use small bypass caps. no i don't expect the bass to shape shift, the midrange to become a liquid or the treble to be sifted of pebbles. just to improve psu impedance and prevent oscillation.  

Adding bypass capacitors does not improve PSU impedance (additional capacitors lower impedance) nor does it prevent oscillation. Bypass capacitor are used to minimize high speed transients or spikes.

To prevent oscillation you need to make sure that you properly compensate your feedback loop and make sure your loop area is small (this is in the amplifier section).

[markcrenz]

Adding bypass capacitors does not improve PSU impedance (additional capacitors lower impedance) nor does it prevent oscillation. Bypass capacitor are used to minimize high speed transients or spikes.

To prevent oscillation you need to make sure that you properly compensate your feedback loop and make sure your loop area is small (this is in the amplifier section).

yun nga, bypass caps will lower psu impedance. di ba improvement yun?

high frequency noise fom the psu can cause some amps to oscillate. bypass caps help prevent this.

[rascal101]

Mas maganda mataas na impedance kesa mababa. Mahirap i-drive kapag mababa impedance.

Kung hindi stable ang feedback loop mag-ooscillate yung power supply kahit ano pang bypass cap ilagay mo.

[markcrenz]

good morning rascal! 

Mas maganda mataas na impedance kesa mababa. Mahirap i-drive kapag mababa impedance.

huh? we're discussing psu, not load, impedance. di ba amps benefit from low impedance psus? yung ibang battery-powered amps nga nag-o-oscilate pa pag low batt kasi high impedance na.

Kung hindi stable ang feedback loop mag-ooscillate yung power supply kahit ano pang bypass cap ilagay mo.

power supply ba o amplifier ang nag-o-oscillate from unstable feedback? 

[ATJr.]

huh? we're discussing psu, not load, impedance. di ba amps benefit from low impedance psus? yung ibang battery-powered amps nga nag-o-oscilate pa pag low batt kasi high impedance na.

you are of course correct....

power supply ba o amplifier ang nag-o-oscillate from unstable feedback? 

kung linear regulated psu, then yung error amplifier nya kapos ng gain after feedback, malamang ang oscillations....

[markcrenz]

you are of course correct....

thanks for the confirmation! makes me proud to know about these stuff despite not having an electrical/electronics degree.

kung linear regulated psu, then yung error amplifier nya kapos ng gain after feedback, malamang ang oscillations....

my line of thought was a linear unregulated psu driving an amplifier, ito kasi recently ang pinagkakaabalahan ni ts qguy. my responses are aligned to this.

oopps.. my bad,  the application is for a Solid State amp, iba ba ang effect ng bypass on SS vs Tube amp ?

but then again i'm also guilty of off-topic postings. 

[rascal101]

good morning rascal!  
huh? we're discussing psu, not load, impedance. di ba amps benefit from low impedance psus? yung ibang battery-powered amps nga nag-o-oscilate pa pag low batt kasi high impedance na.
power supply ba o amplifier ang nag-o-oscillate from unstable feedback?  

Ang ideal voltage source ay infinite impedance. Ang ideal current source ay zero impedance. Ang power supply at battery ay mga voltage source.

Dalawang sections ang linear power supply. Iyung series pass transistor o FET at iyung gain section (feedback amplifier). Nakikita ng feedback loop iyung mataas na capacitance sa input. Kung mababa ang output kailangan niya itaas iyung feedback voltage para bumaba iyung collector to emitter resistance (transistor) o drain to source resistance (FET). Paano niya maitataas iyung feedback voltage ng mabilis kung masyado mababang impedance nakikita niya?

[markcrenz]

Ang ideal voltage source ay infinite impedance. Ang ideal current source ay zero impedance. Ang power supply at battery ay mga voltage source.

A Voltage Source with ZERO INTERNAL resistance is an Ideal Voltage Source.
An ideal current source has an infinite output impedance.
You got it mixed up. Naaalimpungatan ka pa yata.   

[rascal101]

you are of course correct....


kung linear regulated psu, then yung error amplifier nya kapos ng gain after feedback, malamang ang oscillations....

Ang tukoy mo sa baterya ay iyung internal resistance niya o kung sa capacitor ay iyung ESR. Kung mataas nga naman ito hindi makapag supply ng sapat na boltahe ang baterya.

Kung hindi sapat ang boltahe hindi rin sapat at stable ang reference voltage na kailangan ng error amplifier sa linear regulated power supply. Kung ganoon puwede mag-oscillate.

[rascal101]

A Voltage Source with ZERO INTERNAL resistance is an Ideal Voltage Source.
An ideal current source has an infinite output impedance.
You got it mixed up. Naaalimpungatan ka pa yata.   

Hindi naman mali ang sinabi ko at tama rin ang sinabi mo dito. So anong problema?

[markcrenz]

walang problema. masaya ang aking family, work, social life and sexual activities. ehe! im just joking (hint: smiley) na naaalimpungatan ka yata kaya baligtad pagkasabi mo:

Ang ideal voltage source ay infinite impedance. Ang ideal current source ay zero impedance.

i think i've explained enough. a bit too much even.  logging out...

[rascal101]

walang problema. masaya ang aking family, work, social life and sexual activities. ehe! im just joking (hint: smiley) na naaalimpungatan ka yata kaya baligtad pagkasabi mo:
i think i've explained enough. a bit too much even.   logging out...

V = I x R, I = V /R

Ang issue ko talaga ay iyung original na sinabi mo dahil hindi mo pinag-isipan ng maigi. Ang bypass capacitor hindi ginagamit pag-improve ng impedance o pagiwas sa oscillation.

[shrek7]

WOOOOW!!!Goooood Morninnng!!!   

[rascal101]

Ewan ko ba. Parehas lang sinasabi namin pero isip ata naalimpungatan ako.

The glass is half full or the glass is half empty. Alin ba talaga?  

Ang tinutukoy ko ay kapag tinignan mo iyung voltage source o current source from the load side. Kapag sinukatan ba ng ideal na metro anong masusukat niya in terms of impedance at DC? Open ba o short ang voltage source? Open ba o short ang current source?

[ATJr.]

Ang ideal voltage source ay infinite impedance. Ang ideal current source ay zero impedance. Ang power supply at battery ay mga voltage source.

Dalawang sections ang linear power supply. Iyung series pass transistor o FET at iyung gain section (feedback amplifier). Nakikita ng feedback loop iyung mataas na capacitance sa input. Kung mababa ang output kailangan niya itaas iyung feedback voltage para bumaba iyung collector to emitter resistance (transistor) o drain to source resistance (FET). Paano niya maitataas iyung feedback voltage ng mabilis kung masyado mababang impedance nakikita niya?

you got it all mixed up.....Mr. Norton and Mr. Thevenin are angry........they ask me to slap your hand..

http://en.wikipedia.org/wiki/Current_source
http://en.wikipedia.org/wiki/Voltage_source

[ATJr.]

thanks for the confirmation! makes me proud to know about these stuff despite not having an electrical/electronics degree.
my line of thought was a linear unregulated psu driving an amplifier, ito kasi recently ang pinagkakaabalahan ni ts qguy. my responses are aligned to this.
but then again i'm also guilty of off-topic postings. 

you learn a lot of things when you have an open mind.....

[rascal101]

@tonyt, I will slap your hands first  

And, no Mr Thevenin and Mr Norton are smiling  

[jlester87]

Ang napapansin ko lang sa mga circuit design ay pag may dadaanan na mahabang wire/copper trace, saka naglalagay ng bypass cap malapit sa load (yung component na gagamit nung current) to prevent oscillations.

Kung stable naman yung amplifier no need na ng maraming bypass caps. Kahit yung output lang ng linear power supply at power input ng amplifier (end to end ng power supply wires) ang idadagdag mong bypass cap ok na yun. Another gastos at effort lang kung lalagyan mo pa ng iba.

Iilan lang sa mga tweaks ang may significant impact sa sound, at hindi eto yun hehehe...

[JojoD818]

you learn a lot of things when you have an open mind.....

parang Matrix lang ah... free your mind 

[markcrenz]

you learn a lot of things when you have an open mind.....

parang Matrix lang ah... free your mind 

If you keep your mind sufficiently open, people will throw a lot of rubbish into it.
    --William Orton

yun lang! 

[shrek7]

parang Matrix lang ah... free your mind 

wow!!!! favorite ko to!!!! MATRIX!!!  free your mind.... nice!!!