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Old 18th March 2008, 06:33 PM   #1
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Default Choke loaded PSU versus VR tube regulated PSU?

I have a preamp I would like to build but I have yet to decide whether to use a choke loaded PSU or a VR tube regulated PSU. Does anyone have any first hand experience with both? Which did you prefer?
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Old 18th March 2008, 06:49 PM   #2
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Actually, I use both. At the end of the day, the choke was unnecessary, and just added additional cost, weight, and magnetic field issues.

Were I to do it again, I would run the IXYS 10M45S as a current source into the VR tube, losing the choke. Ripple is essentially zero.

I should mention, however, that my linestage is a differential design, not single ended. YMMV when dealing with a single ended topology.
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Old 18th March 2008, 06:54 PM   #3
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Quote:
Originally posted by zigzagflux
Actually, I use both. At the end of the day, the choke was unnecessary, and just added additional cost, weight, and magnetic field issues.

Were I to do it again, I would run the IXYS 10M45S as a current source into the VR tube, losing the choke. Ripple is essentially zero.

I should mention, however, that my linestage is a differential design, not single ended. YMMV when dealing with a single ended topology.
I appreciate your reply. I have been trying to utilize PSU Designer II to help design a shunt regulated supply using a OD3 without much luck. How did you make your calculations?
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Old 18th March 2008, 07:14 PM   #4
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I tried modeling the psu using the VR tube and the 15K load in parrallel as a 4.615K load. I wish the program would allow you to use VR tubes in the model.
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Old 18th March 2008, 07:32 PM   #5
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Screw it. I will just use the choke loaded supply.
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Old 18th March 2008, 11:09 PM   #6
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Quote:
Originally posted by G
Screw it. I will just use the choke loaded supply.

Patience, friend. The rewards are worth it, IMO. Realtor coming over tonite, I'll spend a little time modeling one for you later.
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Old 18th March 2008, 11:12 PM   #7
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Default Re: Choke loaded PSU versus VR tube regulated PSU?

Quote:
Originally posted by G
I have a preamp I would like to build but I have yet to decide whether to use a choke loaded PSU or a VR tube regulated PSU. Does anyone have any first hand experience with both? Which did you prefer?

why not both ?

that's at least what I prefer
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Old 18th March 2008, 11:14 PM   #8
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There'd be no harm to both.

I personally have no VR, just CLCR(i1)CR(i2)C and *hopefully* it should be fine
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Old 19th March 2008, 02:54 AM   #9
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This is my power supply for a Raven style DAC/preamp. As I mentioned, it is a choke loaded supply, which I might not pursue if I were to do it again. As far as using PSUD for the design, I will explain what I've done:

C1-L1-C2 is the typical starting point for the filter. R2 was placed in order to reduce the dissipation of the current source, which is directly after R2. This was due to the fact that I wanted to experiment with different VR tubes and operating points, so R2 gives me a little wiggle room and tweakability.

C3 is completely optional, and even unnecessary. Had the space, decided to put it in.

First current source is the left channel current source. It is placed where it is to simulate the loading on the overall power supply.

The 300 ohm R3 resistor "simulates" the right channel current source. It is selected to produce the VR nominal voltage across C4/I2. If the voltage is incorrect, I tweak R3 until it is correct. Then, I am able to calculate a few things: one, the dissipation in the current source, which is the same as the dissipation in R3. Two, I am able to check the peak output voltage the current source can provide to the load PRIOR to the VR striking. In the example, this is 127V minus the minimum drop of the CCS, around 4V. So my voltage during startup will rise as high as 123V. If my VR doesn't strike at this voltage or lower, it will never strike.

If I need to adjust this available striking voltage, I can do it with R2 changes. A smaller R2 will increase the available striking voltage, while also increasing the dissipation in my CCS.

Actual installation does not include R3 - instead it is replaced by your CCS. As you can tell, this design uses the 0C3/VR105 regulator.

With this approach, PSUD gave me results within about 2V. Ripple values within maybe 10mV.
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Old 19th March 2008, 03:01 AM   #10
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Quote:
Originally posted by zigzagflux
This is my power supply for a Raven style DAC/preamp. As I mentioned, it is a choke loaded supply, which I might not pursue if I were to do it again. As far as using PSUD for the design, I will explain what I've done:

C1-L1-C2 is the typical starting point for the filter. R2 was placed in order to reduce the dissipation of the current source, which is directly after R2. This was due to the fact that I wanted to experiment with different VR tubes and operating points, so R2 gives me a little wiggle room and tweakability.

C3 is completely optional, and even unnecessary. Had the space, decided to put it in.

First current source is the left channel current source. It is placed where it is to simulate the loading on the overall power supply.

The 300 ohm R3 resistor "simulates" the right channel current source. It is selected to produce the VR nominal voltage across C4/I2. If the voltage is incorrect, I tweak R3 until it is correct. Then, I am able to calculate a few things: one, the dissipation in the current source, which is the same as the dissipation in R3. Two, I am able to check the peak output voltage the current source can provide to the load PRIOR to the VR striking. In the example, this is 127V minus the minimum drop of the CCS, around 4V. So my voltage during startup will rise as high as 123V. If my VR doesn't strike at this voltage or lower, it will never strike.

If I need to adjust this available striking voltage, I can do it with R2 changes. A smaller R2 will increase the available striking voltage, while also increasing the dissipation in my CCS.

Actual installation does not include R3 - instead it is replaced by your CCS. As you can tell, this design uses the 0C3/VR105 regulator.

With this approach, PSUD gave me results within about 2V. Ripple values within maybe 10mV.

Interesting. Below is my starting point for the PSU. I need 150v @ 10mA. The I mean for the OD3 is 22.5mA. If I parrallel the load and the current draw of the OD3 I get a 4.615K load. I guess all I need to adjust is R1, R2 and R3 to get about 180v @ 32.5mA at the anode of the OD3 huh?
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