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-1 Phono preamp.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.
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
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:
An externally hosted image should be here but it was not working when we last tested it.
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
Just replaced the bridge rectifier by a tube fullwave, a 5A4R:
same result!
Franz
same result!
An externally hosted image should be here but it was not working when we last tested it.
Franz
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
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
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).
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
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
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
John Broskie writes about the Janus input transformer:
So, this means in other terms 200-0-200 to 275-0-275 VAC.
In my PSUD example you see a 294-0-294 VAC trannie, in the tube circuit.
About the VA of the trannie: I will head for a 100VA R-core tranny to be on the safe side. But this trannie will also include the heather voltage.
VA means nothing else than Voltage multiplied by the current, resulting in VA. But add about factor 1.5 when you calculate with secondary consumption and add some additional safety VA's.
Franz
So, this means in other terms 200-0-200 to 275-0-275 VAC.
In my PSUD example you see a 294-0-294 VAC trannie, in the tube circuit.
About the VA of the trannie: I will head for a 100VA R-core tranny to be on the safe side. But this trannie will also include the heather voltage.
VA means nothing else than Voltage multiplied by the current, resulting in VA. But add about factor 1.5 when you calculate with secondary consumption and add some additional safety VA's.
Franz
Yes, be carefully!
Dont forget to use fuses (I miss them on Broskies boards) with the correct value on the right places:
One before the trannie, primary fuse.
One in front of the high voltage rectifier.
And one in front of the heather voltage.
And, last but not least: use a light bulb in series with the new device, when you power it up the first time. This will enable you to control the current consumption during startup.
And it is in some way a little bit current limiting (but lowering the voltage).
Franz
Having just built an Aikido phonostage usiing Broksie's boards, I can say that a good passive supply (i.e., no regulator) using plenty of chokes works well. I have gone so far as replacing the B+ resistors on the board with off-board mounted chokes. Now it may not be as low of an impedance regulated supply, but you do not hear the regulator artifacts. The sonic influence of a regulator is very noticeable, the best will be neutral and provide excellent low level resolution. However, even a well respected shunt regulator like Allen Wright's SuperReg is influenced by opamp substitution, which tells you that the regulator in the signal path.
I have no doubt that careful shunt regulator selection and implementation will give excellent results, however using a heavily filtered supply using CLCLCLCLC filtration will result in extremely low noise and cause the Aikido phono circuit to perform well at a low risk of complication.
My particular PS setup is using a 120V:240V voltage stepup transformer, with Infineon 600V PIV SiC diodes in a bridge. First cap is 20uF, with a 5H choke into another 100uF. This is followed by a 10H choke into 180 mF, a 15H choke into 150 uF, and finally a 20H choke into 150uF. The final two LC sections are implemented on the Aikido board with off-mounted chokes.
David
I have no doubt that careful shunt regulator selection and implementation will give excellent results, however using a heavily filtered supply using CLCLCLCLC filtration will result in extremely low noise and cause the Aikido phono circuit to perform well at a low risk of complication.
My particular PS setup is using a 120V:240V voltage stepup transformer, with Infineon 600V PIV SiC diodes in a bridge. First cap is 20uF, with a 5H choke into another 100uF. This is followed by a 10H choke into 180 mF, a 15H choke into 150 uF, and finally a 20H choke into 150uF. The final two LC sections are implemented on the Aikido board with off-mounted chokes.
David
Multiple LC section supplies have to be designed very carefully to avoid ringing. Although I've found that some people LIKE the sound of an unstable supply...
I haven't used Allen Wright's regulators before (though the design seems excellent), but given the high intrinsic PSR of the Broskie circuit, if you could actually hear it, you may have some problems in your layout or grounding. Allen uses these regs successfully with cascodes, which have near zero PSR.
I haven't used Allen Wright's regulators before (though the design seems excellent), but given the high intrinsic PSR of the Broskie circuit, if you could actually hear it, you may have some problems in your layout or grounding. Allen uses these regs successfully with cascodes, which have near zero PSR.
As far a choice of rectifiers, it was somewhat a factor of the supply voltage and the transformer. I needed a bridge (meaning at least two solidstate diodes). The SiC Schottky diodes are clean sounding. I have an Amperite delay relay on the mains supply to the B+ transformer which provides the opportunity to rearrange the raw supply a bit to include a tube rectifier in the future. But the SiC diodes sound pretty good to my ears. Still, I am a bit wary of them and intentionally lightened up on the first cap value to avoid heavy current spikes through the devices.
As far as instability and ringing in the power supply with multiple CL circuits, I tend to agree if the supply was getting hammered, i.e., in a power amp. But as I added additional chokes, I noticed a blacker background, better low level resolution AND a relaxed sound. I have not heard anything that would constitute ringing, all the chokes have enough intrinsic resistance to dampen out the ringing of the individual choke, save perhaps for the first choke. This is all still an experiment, and I do want to try adding a regulator at some point in time.
The audibility of shunt regulators was with a different phonostage circuit, and was observed in experiments by myself and a friend, along with several others during an audio meet. Mind you, the root cause for the differences may be some minor amount of oscillation with some of the op-amps, but still, it is audible.
My current tube lineup in the Aikido phonostage is a 6922/12AT7 + 12AX7/6N1P. However, that will probably change in the future as I continue to experiment. I am using a stepup transformer (Hashimoto) and low output MC (Benz Ruby).
As far as instability and ringing in the power supply with multiple CL circuits, I tend to agree if the supply was getting hammered, i.e., in a power amp. But as I added additional chokes, I noticed a blacker background, better low level resolution AND a relaxed sound. I have not heard anything that would constitute ringing, all the chokes have enough intrinsic resistance to dampen out the ringing of the individual choke, save perhaps for the first choke. This is all still an experiment, and I do want to try adding a regulator at some point in time.
The audibility of shunt regulators was with a different phonostage circuit, and was observed in experiments by myself and a friend, along with several others during an audio meet. Mind you, the root cause for the differences may be some minor amount of oscillation with some of the op-amps, but still, it is audible.
My current tube lineup in the Aikido phonostage is a 6922/12AT7 + 12AX7/6N1P. However, that will probably change in the future as I continue to experiment. I am using a stepup transformer (Hashimoto) and low output MC (Benz Ruby).
Great David, thanks for explaining that to me. I think i've come to the conclusion that I will use the shunt regulator from John for the initial power supply to get me off the ground. Then as I become more knowledgable and confident I'll start to experiment with various types of power supplies to see which is most appealing to my ear. One of the most appealing aspects and really one of the major reasons that I purchased the Aikido amp is because of it's high PSRR, so I'm not so sure how much experimenting is warranted with this design and if it would make a huge difference in the performance of the unit. This is of course my amateur speculation on the situation, but it makes sense to me, and I have no problem with being proved wrong, and have many times!! I just love learning as much as I can about these things, and appreciate everyone's input on this thread.
Now, could anyone who has built John Broskie's shunt regulator kit give me some feedback about it? I.E. building difficulties, performance, anything to be aware of, sound, etc.
Now, could anyone who has built John Broskie's shunt regulator kit give me some feedback about it? I.E. building difficulties, performance, anything to be aware of, sound, etc.
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