The stock Aleph 2 used 4 x 22000uF per channel.
I come from the school of thought that says if some is good, then more is better, and too much is just enough. I rigged my Threshold S-500s with extra capacitance...enough to get them up to a quarter-Farad apiece. I'd have done more, but I ran out of caps. Bummer.
The question of how much capacitance is enough is a matter partly of engineering, partly of sound quality, partly of money. The question of capacitor quality comes into the equation, too. The last couple of times it's come up (at least in threads I participated in) people seemed to get contentious. Must be the phase of the moon or something. I'll bow out now and let others contend to their heart's content.
Grey
I come from the school of thought that says if some is good, then more is better, and too much is just enough. I rigged my Threshold S-500s with extra capacitance...enough to get them up to a quarter-Farad apiece. I'd have done more, but I ran out of caps. Bummer.
The question of how much capacitance is enough is a matter partly of engineering, partly of sound quality, partly of money. The question of capacitor quality comes into the equation, too. The last couple of times it's come up (at least in threads I participated in) people seemed to get contentious. Must be the phase of the moon or something. I'll bow out now and let others contend to their heart's content.
Grey
Dansk,
The factory Aleph's did not use inductors in the PSU. A lot of DIYer's decided to build CLC rather than CRC power supply topologies. Either way the Aleph circuits sound fantastic. My A30 uses a CRC configuration. This is the most common and lower cost than CLC.
The amount of capacitance does not matter so much. Most people use as much as they can afford or have space for in their chassis. Grey is right in more is better and a person needs to figure out where they are seeing diminishing rates of return for value. Nelson does a good job
at determining if more parts or more exotic parts are actually beneficial in a meaningful way.
Sticking close to the original design as a basis is usually a good choice. Just my $.02 worth.
-David
The factory Aleph's did not use inductors in the PSU. A lot of DIYer's decided to build CLC rather than CRC power supply topologies. Either way the Aleph circuits sound fantastic. My A30 uses a CRC configuration. This is the most common and lower cost than CLC.
The amount of capacitance does not matter so much. Most people use as much as they can afford or have space for in their chassis. Grey is right in more is better and a person needs to figure out where they are seeing diminishing rates of return for value. Nelson does a good job
at determining if more parts or more exotic parts are actually beneficial in a meaningful way.
Sticking close to the original design as a basis is usually a good choice. Just my $.02 worth.
-David
I must have missed something. Given that the rails in the Aleph 2 are something like 45V, plus or minus a couple of volts, I confess that I'm not clear as to why you're looking at 75V caps. Look at 50V caps, instead. I think you'll find that they're cheaper.
Caps are the sort of thing that surface on surplus sites regularly (unlike big heat sinks). That will also save you a bundle of money. A little patience and a bit of research will generally pay off when it comes to caps.
Hint: When I find a cap that I know I'll need again in the future, I go ahead and buy extras while they're available. By definition, stock at surplus sites tends to be a hit or miss proposition. When they've got what you want, buy it.
Grey
Caps are the sort of thing that surface on surplus sites regularly (unlike big heat sinks). That will also save you a bundle of money. A little patience and a bit of research will generally pay off when it comes to caps.
Hint: When I find a cap that I know I'll need again in the future, I go ahead and buy extras while they're available. By definition, stock at surplus sites tends to be a hit or miss proposition. When they've got what you want, buy it.
Grey
As regards the capacitor voltage, I would personnally keep some safety margin: at "turn on" there can be a short voltage spike, a capacitor ages faster when used near its voltage limit especially in a "hot" class A amp like NP's designs, electrolytic caps are affected by high tolerances etc. I would thus take the next higher standard voltage i.e. 63VDC capacitors, and ideally a 105°C version if there is a risk of excessive heat in the amp (no oversized heatsinks, no air holes, hot summers etc).
More capacitance than in the Aleph2 service manual is a good idea (reducing ripple etc.), but bearing in mind that the larger the caps the longer their load cycle and the higher the inrush current at turn on (need for inrush current limiter).
"75V, 22000uF runs about $35-40 each": I find the price is OK, seen from Europe at least; everything is much more expensive here (capacitors, resistors, transformers, heatsinks etc.)
More capacitance than in the Aleph2 service manual is a good idea (reducing ripple etc.), but bearing in mind that the larger the caps the longer their load cycle and the higher the inrush current at turn on (need for inrush current limiter).
"75V, 22000uF runs about $35-40 each": I find the price is OK, seen from Europe at least; everything is much more expensive here (capacitors, resistors, transformers, heatsinks etc.)
Some hints
Hello
Big/bigger capacitance is good but, it has some requirements:
you need soft start circuit which is able correctly handle initial inrush current during switch on
properly dimensioned transformer
you need rectifier which is able to survive and handle initial inrush current taken by large capacitors. Per my experience you need minimally 50A rectifier for capacitances higher than 47000uF per rail. Also don forgot put some heatsing for rectifier a correctly dimensioned cables and capacitor bank interconnections.
They are basic rules for me.
Good luck.
Tomas
Hello
Big/bigger capacitance is good but, it has some requirements:
you need soft start circuit which is able correctly handle initial inrush current during switch on
properly dimensioned transformer
you need rectifier which is able to survive and handle initial inrush current taken by large capacitors. Per my experience you need minimally 50A rectifier for capacitances higher than 47000uF per rail. Also don forgot put some heatsing for rectifier a correctly dimensioned cables and capacitor bank interconnections.
They are basic rules for me.
Good luck.
Tomas
Surplus caps
Hi Kop89,
Grey is right about surplus sites. Have you looked at apexjr.com?
http://www.apexjr.com/capacitorsR.html#Computer
15000uF 63V at $3 each.
Cheers,
Dennis
Hi Kop89,
Grey is right about surplus sites. Have you looked at apexjr.com?
http://www.apexjr.com/capacitorsR.html#Computer
15000uF 63V at $3 each.
Cheers,
Dennis
> Dear Mr. Pass, Sirs,
I have question about third bridge B3 on power supply schematic (F5 Power Amp) below:
http://www.audiostereo.pl/zalaczniki/1245518_1.jpg
What is main role this bridge ?
Regards
I have question about third bridge B3 on power supply schematic (F5 Power Amp) below:
http://www.audiostereo.pl/zalaczniki/1245518_1.jpg
What is main role this bridge ?
Regards
elac310 said:
I think you're confusing voltage and current. Yes, there is a current spike. No, there's not a voltage spike. Check it with a meter and you'll see. Better yet, use an oscilloscope.
The only time you need caps with higher voltage ratings is if you're running an LC or RC filter. The inductor (or resistor) keeps the operating voltage below the typical 1.4 ratio you'd expect for a filter beginning with a cap. If--and only if--the circuit ceases to draw power, the rail will rise from the reduced rail dictated by the inductor (or resistor) to the 1.4 ratio inherent in the peak AC value. Given that not many people use LC filters these days (it was mainly a tube thing), you'll rarely run into this.
All other factors being equal, higher temperature ratings are good for caps, but I wouldn't get obsessed with it. If you find a good deal on lower temperature caps, buy them. Use them with ventilation and all will be well.
Grey
WBRO said:
This is from one of the Zen projects.
The function of B3 is to provide a connection from analog ground to
AC Earth ground whose diode drop isolates the grounds up to .6V
between each channel and also the Earth ground. This prevents
ground loops while giving shock protection from a line voltage
appearing on a signal ground.
samoloko said:
The caps look good, exactly like the picture:
http://www.apexjr.com/images/15000UFCAP.jpg
I am a little confused on what kind of transformer I need to use. The KK-PCB website shows 600VA, 2x37V secondaries: http://www.kk-pcb.com/power-2.html
But I read somewhere that the rail supply spec is +/- 45V, which suggests 2x33V secondaries.
I am thinking about 1000VA, 2x35V secondaries from Avel-Lindberg. Would this work fine?
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.