View Full Version : Battery for a dynavector p75 mkII
Hi all. I have a DV p75 mkII phonostage and power it from the wall wart that it came with- 12v AC to DC converter. Given that some people are using 12v batteries on beresford bushmaster dac's I wondered if I could do the same for the p75. I know the literature says that the wall wart causes no electrical interference etc but I would be tempted to try the battery approach if it reduced an electrical crap going into the phono stage and the other electrics.
The quality of the power supply has no bearing on the sound quality, read this:
The P-75 mkII also has an advanced power supply that operates from a conventional 12V AC to DC adaptor. This adaptor has absolutely no bearing on the sound quality.
The P-75 mkII power supply runs at over 1/4MHz. It takes the low grade single voltage DC supply from the ac adapter and converts it to the dual high voltages required for true professional quality audio reproduction. The operating frequency is over 12 times higher than the top of the audio band and it incorporates super low noise wideband regulators in its output stage to give ultra low noise supply rails. The internal P-75 mkII power supply is totally self contained and stores many times the maximum possible energy requirements for the phono amplifiers. This means that the quality or size of the external ac adaptor is irrelevant. Increasing the capacity of the external supply will make no difference to the quality of the sound.
awkwardbydesign
27-02-2013, 19:39
So it's switched mode then? Like a computer PSU?
Mike, this is very easy to test, get 8 1.5v batteries, wander down to your local electronics emporium pick up a battery holder and a plug that fits the P-75, wire it all together and see how it sounds. I did something similar to my Lehmann Black Cube and for me it was worth it. YMMV of course.
Mike, this is very easy to test, get 8 1.5v batteries, wander down to your local electronics emporium pick up a battery holder and a plug that fits the P-75, wire it all together and see how it sounds. I did something similar to my Lehmann Black Cube and for me it was worth it. YMMV of course.
Well, you can, but it will make no difference to the sound quality - this is a well known fact so stop adding to his hifi neurosis ;)
Well, you can, but it will make no difference to the sound quality - this is a well known fact so stop adding to his hifi neurosis ;)
Do you want to explain why a/ it will make no difference and b/ who told you it was a well known fact ?
I hope we get something new, not just the tired old "It can't, so it doesn't" nonsense ;)
Audioman
28-02-2013, 09:42
Do you want to explain why a/ it will make no difference and b/ who told you it was a well known fact ?
Dynavector claim it makes no difference because of the design of the internal power supply. Now one would assume they tried this out before making such claims. Worth tryng a better power adaptor or filters to see if interference from that supplied is having an effect though.
I am merely suggesting that one's energies might be spent in doing something that makes a tangible difference (like getting your turntable serviced instead, for example).
The p75 is great (I have one too) but I wouldn't bother if I were you, down that way lies madness, you'll be suspending your cables next!!
StanleyB
28-02-2013, 12:32
I have an inexpensive phono preamp listed on my site that can be used with batteries or with a mains adapter. The differences are startling. The Battery powered configuration gives far better mids and tops.
The Technics battery/mains powered phono preamp that I used to have also produced far better sound with batteries.
So I would expect the Dynavector to produce the same results. A cheap 12V Li-ion battery pack should be sufficient enough to at least offer a starting point.
I have an inexpensive phono preamp listed on my site that can be used with batteries or with a mains adapter. The differences are startling. The Battery powered configuration gives far better mids and tops.
The Technics battery/mains powered phono preamp that I used to have also produced far better sound with batteries.
So I would expect the Dynavector to produce the same results. A cheap 12V Li-ion battery pack should be sufficient enough to at least offer a starting point.
Is this advice, or an advert?
StanleyB
28-02-2013, 12:54
Is this advice, or an advert?
I advertise here all the time and many AoS members own several pieces of kits from me :). But I also offer my own technical input using kits I have actually tried out. So stick to the information provided instead of trying to be cheeky.
sq225917
28-02-2013, 15:04
Is this advice, or an advert?
I was going to ask you the same thing?
While the P75 might be immune to its own noise, chances are the rest of your hifi does not have sufficient high frequency filtering on it if it is more than 5 years old. It's only quite recently that all gear started coming with IEC inlets filtered for HF grunge coming from smps's. Older linear power supplies built into hifi gear tend to be poor at very high frequencies compared to within the audioband.
StanleyB
28-02-2013, 15:53
I was going to ask you the same thing?
Feel free to ask. It won't harm my sales :).
Feel free to ask. It won't harm my sales :).
Must have been an advert then (cheeky, moi?).
Btw - I have a beresford dac (maybe I'll try it with one of those wind up torches).
awkwardbydesign
28-02-2013, 22:04
Dynavector claim it makes no difference because of the design of the internal power supply. Now one would assume they tried this out before making such claims. Worth tryng a better power adaptor or filters to see if interference from that supplied is having an effect though.
And manufacturers are well known for never making unproven claims.
Mike g - The best thing to do is try it. Assuming you don't mis-wire it, you are not going to hurt anything, and you will know for yourself. :) If you do mis-wire it, you will likely be buying a new phonostage...
Anyway, there are a few good bits of information in this thread before it started getting, well, opinionated...
The P-75 mkII power supply runs at over 1/4MHz. It takes the low grade single voltage DC supply from the ac adapter and converts it to the dual high voltages required for true professional quality audio reproduction. The operating frequency is over 12 times higher than the top of the audio band and it incorporates super low noise wideband regulators in its output stage to give ultra low noise supply rails. The internal P-75 mkII power supply is totally self contained and stores many times the maximum possible energy requirements for the phono amplifiers. This means that the quality or size of the external ac adaptor is irrelevant. Increasing the capacity of the external supply will make no difference to the quality of the sound.
This was obviously taken from the manual. (which is good) From this we can determine the following;
The PSU is a switch-mode power supply (SMPS), not a linear supply.
It has a switch frequency of ~250,000Hz, well above the audio range, and not even near any close multiples of something audible.
They also mention that the reservoir capacitors hold much more than the circuit ever fluctuates.
I.E., this is a SMPS that is designed for an audio component. Is this good? Is this bad? That question will quickly devolve into a religious argument, but it is a well-designed supply.
Also, there is one other thing nobody has mentioned, that the inexpensive wall-wart power converter is going to filter quite a bit of the grunge off the AC mains, as it's using an EI transformer that isn't going to couple the HF noise from the mains very well. (that's good) As odd as it seems, the cheap wall-wart is helping.
I have an inexpensive phono preamp listed on my site that can be used with batteries or with a mains adapter. The differences are startling. The Battery powered configuration gives far better mids and tops.
There is no doubt that the battery supply would greatly help an 'inexpensive phono preamp' as it will undoubtedly have a poorly-designed and likely undersized linear PSU. Batteries will be simply be quieter in that situation.
So, what is my suggestion? Try the batteries. You will then know if there is a benefit or even a difference. In this particular situation I don't think there will be a change. There are many different situations where I would unashamedly cheer for the construction of a battery supply.
sq225917
01-03-2013, 06:57
Stanley I was referring to Ossy's DV advert, not your post.
Looks like all my arguements have been covered, thank you everybody, saves me typing :)
Anti Meep
06-04-2013, 07:19
I may be a bit late to chime in on this but never the less...:)
I have the DV P75 mk2 running with my Well Tempered Amadeus. Both use very similar switch mode PSU's and both introduced ground loop noise into my system. I replaced them both with locally made linear regulated wall wart PSU's. No issues now and all is well. The technician I spoke to mentioned that he had plenty of experience with cheap switch mode PSU's introducing ground loop type issues into all sorts of situations. He also said Switch Mode PSU's are just cheap and that's about it!
Very helpful he was:)
Also I feel the battery way is worth a crack. Where I live some times the power supply just seems really bad. Certain times in the weekends are worse. Almost as if the whole street has all the appliances going at once. You know, everyone has the washing machines and vacuums going at the same time. One time when this was happening I connected an old style isolating transformer to my main mains plug and presto. It all sounded better, smoother, less sort of noisy and frenetic.
Just an observation.
Craig.
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