Power Supply for Aikido Phono Pre

[Binaural]

I have purchased the Aikido phono pre board from John Broskie and have some questions about constructing the power supply. He has a couple of sample schematics in the included booklet (can be viewed on the net at http://www.tubecad.com/2008/07/13/PH...o%20preamp.pdf) Basically I'm not sure how to find the values to purchase the parts I need. I'd like to use a 5ar4 tube rectifier instead of the published FRED's in the guide, and I'm pretty sure I know how to implement those, just not sure of the surrounding component values and the voltage of the power transformer I would need. I have seen people build aikido circuits here, but there isn't much (that I could find) info on the power supplies, especially for this particular board. Any info is greatly appreciated.

[Franz Gysi]

To answer you questions yourself, you best download the free PSU Designer from Duncan's Amp Tools:

http://www.duncanamps.com/psud2/index.html

Very adequate simulation is possible.

Here I show you, what I will use in my Aikido phono pre:



Some notes:

I used a stepped load, first just 10uA, increasing after 3 seconds to 45mA. This is to see the idle voltage and the behaviour under load.

It is important, to know the DC resistance from the tranny.

To fine adjust the voltage, I can change the value from C1, therefore the odd value.

Franz

[Franz Gysi]

Just replaced the bridge rectifier by a tube fullwave, a 5A4R:

same result!



Franz

[Stixx]

I do wonder how you can get the exact same result when one knows that a tube rectifier drops 30 or so volts??

And your stepped load seems to step from a tiny 10 microampere (10uA) to the specified 45mA...

Maybe worth further investigation

[Franz Gysi]

Believe it or believe it not: This is the result from the small C1 value.

When you replace C1 by a 100uF cap, the simulation shows a difference between solid state or tube rectifier.

And the stepped load: yes, this is my intention. Start with 10uA to see the idle voltage, and then step to 45mA.

Don't worry, I have nothing to investigate, as I work for several years with PSUD and the results are very accurate.

Franz

[Binaural]

Franz,
Great, thanks for the link. I'll be downloading and trying out that software hopefully sometime this weekend. What tubes did you select for your phono pre and what did you select for your B+? Also what are your thoughts on the sound of your pre?

[Stixx]

Believe it or believe it not: This is the result from the small C1 value.

No problem with believing...you are correct!

I've built a psu with a small first cap myself to be able to finetune B+ (headphone amp), and I also simulated that in PSUD before I built it...but I just used an EZ81 tube rectifier and wasn't aware that in fact B+ changes very little using the small first cap and either tube or SS rectifier.

What I noticed was that you seem to be able to input values with a 'decimal point ' instead of the 'comma'...


PS. I've also built an Aikido (headphone amplifier).

[JoshK]

Why not use the Janus kit? If you are looking for a simple no thought solution, then that is it. But I agree with others, that you should learn to use the Duncan PSUDII.

[Franz Gysi]

What tubes did you select for your phono pre and what did you select for your B+? Also what are your thoughts on the sound of your pre?

My phono pre is not finished yet.

I used the configuration for ECC83 as voltage amplifiers and E188CC as cathode followers and 300V B+.

And in the input I will use some Studer 1:10 stepups, to drive the amp with my TSD15 or a DL103.

As soon as I have free time, I will power it up on my workbench with my old regulated Heathkit power supply, to find out the best Ub+ by listening.

After that, I will design the psu and finish the project.

Another tip for using PSUD: begin with the available transformer. You have to know the DC resistance of the transformer, very important to have good results.

And one tip more, for the beginner with PSUD: just move the mouse cursor over the circuit.

You will see different yellow areas, where you can rightclick some appopriate actions like changing from bridge to tube fullwave or like inserting a LC or RC chain. Even for changing values of the parts.

Kind regards
Franz

[Binaural]

Franz, yes it has helped me understand how different values affect the circuit just by playing around and not having to worry about killing myself of blowing something up!

Now heading back to the shunt regulator suggested by Josh, I have been trying to find an adequate power transformer but I'm not really sure what specs I need. I know I'll need between 400 and 550V according to the website, although that sounds awful high, but I guess it looses a lot in the circuit? Also I'm not sure about the secondaries to get 12.6v for the heaters. VA is something else i'm not sure about. Any suggestions? Mfr, part #'s? Thanks