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Using a Pyramid PSU with a V-DAC: Polarity Concerns

post #1 of 32
7/21/10 at 8:30pm
Thread Starter 

I was wondering if anyone out there who has used a Musical Fidelity V-DAC with a Pyramid PSU (or any regulated aftermarket power supply) knows what the polarity of the 'tip' of the cable/adapter needs to be. I am assuming that the 'tip' is the interior of the adapter, and that the exterior (most visible) is the barrel. I have read reports that the tip polarity is positive, but there are also some that state that it is negative. As there is no concrete info. available through the MF site, and they do not provide an email address to make inquiries, I am stumped. I do not have the stock wall-wart, and therefore cannot check the polarity based on any markings, which, frustratingly, are not present on the DAC itself. I assume that if I have the polarity reversed, bad things will happen. So, a BIG thanks in advance for any verifiable information. Cheers! :)


Edited by sampson_smith - 7/21/10 at 8:32pm
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post #2 of 32
7/21/10 at 8:40pm

Edited:

why not measure what you have now, and wire the thingy you want to use the same way?


Edited by nikongod - 7/21/10 at 8:43pm
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post #3 of 32
7/21/10 at 9:42pm
Thread Starter 

Thanks for the reply. So, I assume you mean that I can first hook up the power cord plus adapter plug to the Pyramid amp, turn it on, then measure the output using a multimeter (without also plugging in the V-DAC)? I am sure that I can designate, based on either the connection to the Pyramid PSU or tip orientation, whether the tip be positive or negative. But, I assume that where the V-DAC is concerned, it will only safely tolerate one of the two. Is there any possible way to 'measure' the V-DAC to determine what tip polarity input it needs?

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post #4 of 32
7/21/10 at 11:07pm

Unless I am missing something....I would think you could measure the polarity of the existing power supply and figure it out?

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post #5 of 32
7/21/10 at 11:43pm
Thread Starter 

The only power supply that I have - the Pyramid PSU - is capable of + or - tip polarity, interchangeably. The polarity can both be switched at the PSU or the polarity can be inverted at the tip end by turning the detachable tip around. I do not have the stock wall-wart that normally comes with the V-DAC, so I cannot view [based on the (-)---(o---(+), for example, of the label, if it is marked correctly] or measure the polarity of it. It comes down to finding out what tip polarity the V-DAC actually requires, which I assume I cannot measure using a multimeter and the V-DAC alone. Thanks for the help! :)

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post #6 of 32
7/22/10 at 1:10pm

The DIY approach would be to take the DAC board out of the enclosure and follow the traces on the circuit board but....

 

http://www.head-fi.org/forum/thread/502916/sold-musical-fidelity-v-dac-with-an-upgraded-power-supply

 

The pictures look like center positive to me but it may be a good idea to double check with the seller.

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post #7 of 32
7/22/10 at 1:37pm
Thread Starter 

Awesome work, MisterX. It is very much appreciated. It appears that reputable sources indicate that the tip should be center positive, with only a few spurious comments by those with very few posts indicating otherwise. I would rather not open up the V-DAC - due to warranty concerns - but feel that the above link is enough to solve the mystery. I can't see it very clearly, but it looks like [tip] marking on the cable is aligned with the +'ve marking on the adapter/'tip'. (I assume, because I cannot see it clearly, that the +'ve marking is consistently under the metal tipped side, and the -'ve marking on the back of the adapter, away from the metal.) So, good show! Thanks again. :)


Edited by sampson_smith - 7/22/10 at 1:39pm
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post #8 of 32
7/28/10 at 7:10am
Thread Starter 

For confirmation's sake to help out future V-DAC users that want to use a Pyramid or related PSU to improve performance, the tip is most certainly center-positive or '(-)---(o---(+)', as is correctly written on the supplied wall-wart. I am currently loving the V-DAC with my Gilmore Lite amp and HD600's, using this upgraded power supply option.

 

Thanks again all for helping me get to the bottom of this! :)

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post #9 of 32
8/11/10 at 8:36pm

Sampson,

 

(or anyone who may know about this issue)

 

I'm not a "regular" on HeadFi, however, I saw some of your posts related to V-DAC. I am researching polarity on V-DAC as I am also using an outboard power supply with it. When I used a Negative polarity on the inside of the barrel (based on apparently false info I had read in an amazon.com review), the V-DAC wouldn't power up. Upon switching the inside to Positive (by reversing my Adaptaplug from Radio Shack), the DAC powers up and sounds incredible.

 

So....I would greatly apreciate your help on this....Has it been "officially" confirmed that the inside of the jack is Positive as I suspect....or are you fairly sure that that is the case? 

 

Since I am a non-techie, it would be great to know that I've got it plugged in properly and that I won't do harm to the unit.  Please advise.

 

Thanks,

Audiohound

 

PS: I also sent you a PM, but posted here too in case that fails.

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post #10 of 32
8/11/10 at 9:10pm

As a prior V-dac & Pyramid owner I can 100% confirm tip positive on the PS. (This seems to be the case for most electronics). A multimeter helps. 

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post #11 of 32
8/11/10 at 9:51pm

@ audiohound: so one way working and the other not doesnt provide any clues? i'm surprised you didnt kill it when you hooked it up wrongly the first time. would be wise to MAKE SURE before going ahead based on a hunch in future

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post #12 of 32
8/12/10 at 9:31am
Quote:
Originally Posted by johangrb View Post

As a prior V-dac & Pyramid owner I can 100% confirm tip positive on the PS. (This seems to be the case for most electronics). A multimeter helps. 


Thanks, I really appreciate it, johangrb ....as well as others who have responded.
 

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post #13 of 32
8/13/10 at 8:38pm

I have two more questions regarding using an outboard PSU with the V-DAC, please:

 

1) The PSU I'm using is virtually identical to the Pyramid - spec-wise, chassis, etc.  However, my PSU's AC plug is non-polarized. Both blades are identical, one is not wider than the other, so you can plug it into the wall "either way." I thought I had read that - in situations like this - plugging it in one way vs. the "opposite" way reverses the "polarity" - and hence, affects the digital sound.  Is this true - and if so - what type of "polarity" are we talking about here ...does it have to do with "phase" as opposed to simple negative vs. positive electrical current? Please explain to this non-techie, and what do I listen for as I try to determine the best "direction" to plug it in? 

 

2) I purchased my PSU prior to getting the V-DAC, as I was using it to power a Pyle 7" LCD Monitor which I use for DVD-Audio discs (since my sound system is not connected to a TV). Can I safely connect and use both the V-DAC and the monitor at the same time? Both require 12V. 

 

Thanks,

Audiohound

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post #14 of 32
8/13/10 at 9:04pm

Wesley Crusher could make the Enterprise do anything by reversing the polarity. 

 

But seriously, the AC plug has no fixed polarity. It's alternating, after all. So it will work either way. The larger blade on some plugs is only for safety concerns on appliances that have an on/off switch. So that the "live" wire would be fully disconnected when the appliance is switched off. If not it would be a shock hazard on things like light bulbs and toasters. Should be fine with the Pyramid. Just don't open up the enclosure while it is still plugged in.

 

 

Quote:

Originally Posted by audiohound View Post

I have two more questions regarding using an outboard PSU with the V-DAC, please:

 

1) The PSU I'm using is virtually identical to the Pyramid - spec-wise, chassis, etc.  However, my PSU's AC plug is non-polarized. Both blades are identical, one is not wider than the other, so you can plug it into the wall "either way." I thought I had read that - in situations like this - plugging it in one way vs. the "opposite" way reverses the "polarity" - and hence, affects the digital sound.  Is this true - and if so - what type of "polarity" are we talking about here ...does it have to do with "phase" as opposed to simple negative vs. positive electrical current? Please explain to this non-techie, and what do I listen for as I try to determine the best "direction" to plug it in? 

 

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post #15 of 32
8/13/10 at 9:44pm
Quote:
Originally Posted by Yoga Flame View Post

Wesley Crusher could make the Enterprise do anything by reversing the polarity. 

 

But seriously, the AC plug has no fixed polarity. It's alternating, after all. So it will work either way. The larger blade on some plugs is only for safety concerns on appliances that have an on/off switch. So that the "live" wire would be fully disconnected when the appliance is switched off. If not it would be a shock hazard on things like light bulbs and toasters. Should be fine with the Pyramid. Just don't open up the enclosure while it is still plugged in.

 



Thanks, Yoga Flame: Your explanation is so clear and easy to understand. You saved this tweakaholic from staying up all night and endlessly reversing the wall plug while listening carefully!

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