The VR MINI Ultracapacitor Power Supply Thread

[Vinnie Rossi]

All,

 

Welcome the to VR MINI general discussion thread!

 

Last month we began shipping the VR MINI. Here is a link to the MINI page: Vinnie Rossi MINI PURE DC-4-EVR Power Supply

 

 

http://www.vinnierossi.com/mini/

 

Please let me know if you have any questions.

 

Thank you,

 

Vinnie

[Vinnie Rossi]

moussaobeid said:

Hi Vinnie

I am currently enjoying my MINI with my Brooklyn DAC, it never sounded better.

Hi Moussa,

 

AWESOME - thank you for posting your impressions of the MINI feeding your Brooklyn dac!

 

 

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My question is why don't you make a variable voltage so the customer can select the voltage depending on the device to be powered by the MINI? Is it cost or performance related?

 

Excellent question! There are mainly two reasons why I did not make the voltage on the MINIuser adjustable:

 

Brian Lowe at Belleson ran various tests and determined at the noise performance of the SPVR-X was not as good with an adjustable implementation. This was because adding switches (or a potentiometer) increased the trace lengths and degraded the quality of his patented super regulator design. Nothing performed better than a high quality, fixed resistor directly on the SPVR-X regulator board - where the circuit path of the regulator is just a few mm long instead of a few cm long. It makes a big difference when you are dealing with this level of low noise.

 

Best regards,

 

Vinnie

[Vinnie Rossi]

Duke40 said:

Just placed an order for a 19V MINI for my Auralic Gemini 2000 DAC/Headamp.

(Higher voltage MINI's in the 15 to 24 Vdc range are now available to be ordered).

Already have a 12V MINI from Vinnie Rossi, for my Auralic Aries and I am pleased with the performance improvement, so really look forward to the 19V MINI arriving.

My headphone rig will then be totally "off-grid", isolated from the AC mains.

 

Hi Duke,

 

Thank you for your post!

 

 

Vinnie

[Vinnie Rossi]

Quote

Special pre-order price of $1095 until the end of this month. Then the regular price will be $1295.

 

All,

 

Just a reminder that the pre-order pricing for the 15 - 24Vdc VR MINI power supply ends this Friday, March 31st.
We've been building away and have all parts in stock.  Current lead time is within 2 weeks.

http://www.vinnierossi.com/mini/

Best regards,

Vinnie

[Vinnie Rossi]

Hi John,

 

Many thanks for your post! 

 

This thread on the Vinnie Rossi forum (Audiocircle) was also posted about the 24V MINI:

http://www.audiocircle.com/index.php?topic=148925.0

 

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On the back of my 19V VR MINI power supply, between the heatsink and the IEC ac input, is a silver thread and nut.   Is this some sort of grounding post, or does it fulfil another purpose ?

 

 

Yes, it connects to earth ground (3rd prong of the power cord) - just in case someone is using it with a phonostage or equipment that is connected to other non-isolated equipment that is picking up hum. 

 

Enjoy it!

 

Vinnie

 

 

[Vinnie Rossi]

Hi Kin,

 

Brian from Belleson has tested the custom Belleson  super-regulator that we use for the output of the VR MINI,

and confirmed that when a switch (or variable resistor) is used to allow for voltage adjustment, the is always a

noise penalty associated with it. 

 

I decided that added noise penalty would take away from the VR MINI's competitive advantage over all other power supplies in its voltage/power range, so I will not be offering it.

 

Thank you for your understanding,

 

Vinnie

[Vinnie Rossi]

1 minute ago, sgr said:

Hi Vinie,

 

Do you think the Mini could power the Legacy Audio WaVelet?

It is a preamp, DAC, crossover, and DSP and it controls my Legacy V speakers. 

 

Here re are the specs:

 

 

    115V AC input Detachable cord

        Compatible 115-220V inpuT

        12.83V minimum,13.68V (Bill: please confirm this still works for Wavelet)

        5-Amp minimum

        60 Watt minimum

        Black case

 

Thanks,

steven

Hi Steven,

The VR MINI has a max continous output current rating of 2.5A.  It looks ike your product requires at least 5A, so it will not do the trick.

 

Best regards,

 

Vinnie

[Vinnie Rossi]

Hi sefischer1,
I'm not sure if the 12V, 6000mAH Li-ion pack you were using has an output regulator or not? 

If it was just a battery pack w/o output regulator, be careful because the starting voltage will probably be > 12V and the shut off voltage will probably be < 12V.  I'm not sure if the Nagra VPS is ok with this.

 

If the battery pack has an output regulator that follows it, is it a switching regulator or linear regulator?

Your VR MINI uses a 12V, linear, Belleson Super-Regulator.  See:
https://www.belleson.com/store/SPZ-High-Current

It not only might be cleaner, but it could have a lower output impedance over a wider frequency range compared

to what you were using.

As far as timing between bank switching, I would need to time it with a 0.6A load.  I would think it would be

>10 seconds between switching banks, but would need to verify.


Regarding the link that esldude points to:

 

Yes, the AC live goes through the transformer (but the transformer is just in series, just like an inductor), before going to the SMPS charging supply, which then feeds a linear current regulator on the board above it that provides constant current charging to the two ultrcacap banks on that board, which then feed the linear Belleson super-regulator on the output side, and then to the output jacks.

Initially, the large transformer inside was to be used as a step-down, but with the first small batch of supplies some customers were finding them to be mechanically loud, in terms of hum/buzz (I didn't have this issue on my bench when we tested them before shipping, so I think they were sensitive to noise/harmonics on the AC line in some homes).  So now you can't think of it as a step-down transformer.

 

I am aware of Amir and his post on ASR forum.  I've spoken direclty to him about it.   Even with the very small amount of AC leakage via the SMPS charger, the DC output is very clean.  The worst is -115dB at 60Hz (this is only about 20uV at 60Hz for the 12Vdc output.  At higher frequencies, the output is better than -126dB.  That's noise... not a measurement of output impedance vs. frequency.

There have been articles written about the AC leakage via the small Y-caps in a SMPS.  Again, its very low (about 20uV), but it is common-mode and the Belleson will not filter it, and it does creep base the bank switching MOSFETs in the mini.

You'll find on the Uptone forum (regarding their LPS-1 and its SMPS charger) a suggestion by John Swenson to Earth Ground the DC output (-) terminal, thus shunting any SMPS leakage to GND.  You can also try this with the MINI, but it could cause a ground loop with your other equipment. 

 

But can you even notice the 20uV of noise?  Not sure what the SNR of your gear is, so I don't want to speculate yes or no.

The important thing to note is that the VR MINI's 12Vdc output is very clean over a wide freq. range, as is load regulation and output impedance (specs are on the Belleson website).  

 

Quote

Your supply results in a complete lack of low-frequency noise compared to the Nagra supply. I suspect that the output impedance of your supply is much lower than the Li-Ion battery pak and this may cause some interaction with the Nagra's internal voltage stepup circuitry.  Any thoughts?

Glad to hear - it sounds like it is doing what it is meant to do then!

Thank you for your post,

Vinnie
 

[Vinnie Rossi]

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[Vinnie Rossi]

Hi sefischer1,
 

Quote

I understand from your comments that the SMPS is driving the constant current source used to charge the bank. This implies that the other bank is disconnected (via MOSFET switch I assume) while delivering voltage to the output.   

 

Correct, the bank in use (not the one that is charging) is disconnected via the MOSFET switches.

 

Quote

Does this mean that the small AC leakage results from RC coupling between the charging and supplying banks, such coupling resulting from proximity and finite MOS switch open resistance?

The AC leakage current comes from the Y-caps used inside the charging supply.  It gets coupled onto the DC output as common mode noise, and a very small amount of it even leaks through the MOSFET switches because a MOSFET is not a perfect switch in that there are still internal capacitances and resistances between its 3 terminals. 

So instead of getting something like -126dB (or better) across the entire band from 0Hz to > 100kHz, there is the AC leakage that shows at 60Hz (or 50hz, depending on where you live) at around -115dB (which is about 20 microvolt of noise per 12V output.  Again, very, very little, but noted), and less of it at harmonics of 50 or 60Hz.   So it is a very quiet supply, and other parameters such as output impedance vs. frequency are not affected, (but are also very important, as audio equipment is rarely acts as a constant-current DC load because the DC current drawn can change over time, even very briefly, and the power supply needs to be able to cope with this).

 

Best regards,

 

Vinnie