It depends on whether you make one or two power supplies....
There are all kinds of variations you can make here....
I'm personally just using a single power supply but I also have a bit of extra capacitance...I'm going to run 4 (maybe 6 I'm still thinking) x 33,000uF of capacitance because I found a surplus store that sold the 33,000uF caps for $15 each.
There are all kinds of variations you can make here....
I'm personally just using a single power supply but I also have a bit of extra capacitance...I'm going to run 4 (maybe 6 I'm still thinking) x 33,000uF of capacitance because I found a surplus store that sold the 33,000uF caps for $15 each.
Oh dear, oh dearie me...
Now, you're getting into perilous waters. I'm going to keep this short, 'cause I'm short on sleep. If you want to mess with it in more detail, catch me when I'm fully awake.
The filter section can begin with a resistor, a cap, or an inductor. Most people don't pursue the resistor option (at least not for audio), so we'll ignore that one for the moment. Generally speaking, if you begin the filter with a cap, you'll get more voltage, but less current capability. If you use an inductor first, you'll get a lower voltage, but more current capability. I suppose that it goes without saying that these parameters have to be balanced with the circuit draw and the power transformer parameters.
As a practical example, the power supply I'm using for my tube phono stage starts with an inductor. The transformer had more voltage than I needed; if I'd used a cap input filter, the voltage would have been on the order of 545V. Since I only wanted a 300V rail, but wanted lotsa current (6922s are hungry little devils--they draw about ten times the current that a 12AX7 does), I started with an inductor, which gave me a beginning rail of about 350V, which I then regulated down to what I wanted.
Does that help?
Grey
Now, you're getting into perilous waters. I'm going to keep this short, 'cause I'm short on sleep. If you want to mess with it in more detail, catch me when I'm fully awake.
The filter section can begin with a resistor, a cap, or an inductor. Most people don't pursue the resistor option (at least not for audio), so we'll ignore that one for the moment. Generally speaking, if you begin the filter with a cap, you'll get more voltage, but less current capability. If you use an inductor first, you'll get a lower voltage, but more current capability. I suppose that it goes without saying that these parameters have to be balanced with the circuit draw and the power transformer parameters.
As a practical example, the power supply I'm using for my tube phono stage starts with an inductor. The transformer had more voltage than I needed; if I'd used a cap input filter, the voltage would have been on the order of 545V. Since I only wanted a 300V rail, but wanted lotsa current (6922s are hungry little devils--they draw about ten times the current that a 12AX7 does), I started with an inductor, which gave me a beginning rail of about 350V, which I then regulated down to what I wanted.
Does that help?
Grey
Thanks for all of the information guys. If you couldn't tell already this is my first real diy project and I'm trying to take it slow and understand what's going on. This forum has been an invaluable resource, as has being able to obtain info from the designer of the amp itself. Thanks to Nelson, Grey and everyone else who has been patient and generous with their time.
Thanks guys,
Rob
Thanks guys,
Rob
O.K. now about the rated voltage needed for the caps. I'm going to be powering my aleph with a 1010 VA transformer using dual 37.5 volt primaries. Assuming no loss due to the rectifier for now that would mean my capacitors will each be seeing 53 volts rms of dc, but they will also be seeing a peak of 75 volts. On top of this I heard somewhere that a twenty percent change in voltage provided by the power company is not uncommon, on the otherhand I've read of people running an aleph 4 using 50 volt PSU caps so what kind of voltage rating do I need on these caps? Are the figures I came up with accurate.Thanks.
Rob
Rob
So when I wire two power sources with the same voltage, in this case the dual primarys, in series I end up with the same voltage I would obtain from wiring just one of the primarys to the same circuit. Is that the general idea? I didn't know if that was the case or not and took the guess that you could add voltages. Just curious how does a wave with peak 53 volts create a relatively similar consistent voltage? Oh, well thanks for the correction.
Rob
Rob
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