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RME DPS-2 Linear Power Supply

Reddoc

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For a thousand-plus dollars, any OCD audiophile can buy 12V car batteries
Are batteries electrically "silent" ie perfect voltage / current source with no extraneous noise?
Obviously things change as battery voltage falls with drainage but for the first X% of its use, is the battery as perfect as anyone could want?
 

antcollinet

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Are batteries electrically "silent" ie perfect voltage / current source with no extraneous noise?
Obviously things change as battery voltage falls with drainage but for the first X% of its use, is the battery as perfect as anyone could want?
Depending on internal resistance of the battery - any dynamic load (varying current) will result in a varying voltage on the output of the battery.
 

MC_RME

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Are batteries electrically "silent" ie perfect voltage / current source with no extraneous noise?

Basically yes. If you attach a battery to the APx input you get a super flat and low FFT result, not much different than shorting the APx inputs. As such a battery is a good reference of a pure voltage/current source. Even if you load the battery and draw some current.

Obviously things change as battery voltage falls with drainage but for the first X% of its use, is the battery as perfect as anyone could want?

Yes. But in case of current it really depends on the type of battery. While cheap standard AAA might have an internal impedance of several ohms, my preferred Li-Ion rechargeables operate in the milli-ohm range (18650 type and up). No wonder as they can easily spit out 10 A and more...
 

Curvature

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I have a 20+ year old, single ended Meridian 556 poweramp, and I can hear NO hum or noise with my ears to the speakers, at night, in a dead silent room.
Meridian had quoted a noise figure of -90dB for the amp.
All this talk regarding audible noise and hum is a bit over rated.
Depends on the signals of interest and sensitivity of attached devices.

"Dead silent" has numbers attached, too.
 

Ken Tajalli

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"Dead silent" has numbers attached, too.
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No it doesn't! it simply has a threshold value, which varies for reasons you touched on.
Numbers are for measurements. The operative word here was Audible.
A straight piece of wire can have measurable noise.
 

Bernd

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RockShop offers this for 1.049 EUR.

Will definitely keep my ADI-2 Pro FS R stock power supply...
A linear power supply for an ADI-2 (PRO) FS is a little nuts already but at this price it is ridiculously overnuts!
 

fredoamigo

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If it weren't for the protection, which isn't insignificant, I wouldn't have any use for it.
 

Curvature

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View attachment 366605
No it doesn't! it simply has a threshold value, which varies for reasons you touched on.
Numbers are for measurements. The operative word here was Audible.
A straight piece of wire can have measurable noise.
Ok, to be more clear, I think you are probably overstating how quiet your room is, and if you show a measurement or give an NC value we could give the context that would let us compare to the audibility of "-90dB" noise (although without specifying bandwidth or level that number is fairly abstract). Regardless, my point is that, as many people who post on ASR saying that X figure will cause audible problems, there are as many who jump in and say, like you, that X isn't a problem. What's really necessary is to give some sense of context and surrounding circumstances. For this thread, and this product, the DPS-2, @MC_RME and @KSTR provided the context that lets use understand the use case.
 

Ken Tajalli

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Ok, to be more clear, I think you are probably overstating how quiet your room is, and if you show a measurement or give an NC value we could give the context that would let us compare to the audibility of "-90dB" noise (although without specifying bandwidth or level that number is fairly abstract). Regardless, my point is that, as many people who post on ASR saying that X figure will cause audible problems, there are as many who jump in and say, like you, that X isn't a problem. What's really necessary is to give some sense of context and surrounding circumstances. For this thread, and this product, the DPS-2, @MC_RME and @KSTR provided the context that lets use understand the use case.
See! you are over complicating the matter, and possibly putting words in my mouth!
-90dB figure was what Meridian claimed to be the noise floor, can be disputed.
My speaker's efficiency is unknown, how quite is my room is unknown, how sensitive my ears are, is unknown . . . . do you get my drift??
The word Audible, is a description without an exact figure, it has a sort of a range. let us say (for the sake of argument) -90dB or so.
I only meant that reducing the noise on this device from -100dB (or less), by using the new PSU, is not going to be audible. Others have correctly pointed out, that the new PSU, can help with using the device as a measurement ADC/DAC, where absolute noise floor would be important.
It was a reply to a post that possibly suggested it might have been Audible.
Again don't look or demand for exact figures, when it comes to Audible or Visible or such subjective descriptions.
 

Curvature

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Again don't look or demand for exact figures, when it comes to Audible or Visible or such subjective descriptions.
I would disagree—I would say that it is exactly when audibility is concerned that figures are necessary to test claims and understand potential use cases and impacts.

What I don't like is people throwing around "audible" or "inaudible". Easier and more productive to discuss the data.
 

antcollinet

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I would disagree—I would say that it is exactly when audibility is concerned that figures are necessary to test claims and understand potential use cases and impacts.

What I don't like is people throwing around "audible" or "inaudible". Easier and more productive to discuss the data.
OK - here is the closest we have for a hypothesis on that here at ASR. So far no-one has disproved this, as far as I know, even for the lenient limits.

Audibility thresholds of amp and DAC measurements
 

Curvature

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OK - here is the closest we have for a hypothesis on that here at ASR. So far no-one has disproved this, as far as I know, even for the lenient limits.

Audibility thresholds of amp and DAC measurements
Disprove isn't the right word. There are high-sensitivity speakers, microphones and headphones/IEMs out there that cause hiss to be audible where it otherwise wouldn't be. Listening distance is also a factor for hiss audibility for speakers, too, and tweeters generally have to be attenuated relative to woofers or subs. Take the smaller miniDSP (can't remember the name) released a few years ago, which had reports of hiss despite having what would otherwise be considered good measured results for people who used it for active crossovers.

If we don't bother to consider the range of uses a product can have, we will end up making reactionary statements, claims or giving advice too far to one direction or the other.

I happily use an old midrange Yamaha AVR because I understand how the chain interacts. I wouldn't recommend it to someone looking to use hornspeakers, or who wants to use the headphone jack, or the phono input.

It doesn't take that many extra words to go from, "it's an audible/inaudible problem", to some extra context that helps people think more clearly.
 

Ken Tajalli

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Disprove isn't the right word. There are high-sensitivity speakers, microphones and headphones/IEMs out there that cause hiss to be audible where it otherwise wouldn't be. Listening distance is also a factor for hiss audibility for speakers, too, and tweeters generally have to be attenuated relative to woofers or subs. Take the smaller miniDSP (can't remember the name) released a few years ago, which had reports of hiss despite having what would otherwise be considered good measured results for people who used it for active crossovers.

If we don't bother to consider the range of uses a product can have, we will end up making reactionary statements, claims or giving advice too far to one direction or the other.

I happily use an old midrange Yamaha AVR because I understand how the chain interacts. I wouldn't recommend it to someone looking to use hornspeakers, or who wants to use the headphone jack, or the phono input.

It doesn't take that many extra words to go from, "it's an audible/inaudible problem", to some extra context that helps people think more clearly.
You do have a point. Let me help you here.
- Measured electrical noise, does not directly equate to actual sonic noise out of a transducer. Consider this:
take two amplifers, both with noise-floors of -100dB, but one is 100W and the other is 1000W. If you measure the noise voltage of the two amplifiers, you will see that one is over 3X the other (+10dB)! plugged into same speakers, one can have audible noise, while the other may not.
Also, the bigger amp has 10dB more gain, which would amplify any noise fed into it.
Of course there are other factors, such as the ambient noise level, the sensitivity of the transducers, the frequency bandwidth of the noise, the sensitivity of the hearing of the person ...... So it is not set in stone or one size fits all, but I would say an electrical noise of at least -90dB, out of a 200W amp into a transducer of less than 92 dB for 1W (I chose some typical values) would yield an inaudible noise for most people/situations.
- However, in this particular case, the standard device has such a low noise floor (and we are talking noise-floor not SINAD) that any reduction by using the new PSU, is not going to tip the audibility of noise.
 
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sonitus mirus

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I'm not that thrilled about having another cumbersome space heater in my office, but I would be more inclined to go with the new LNI-2 DC to remedy any potential current leakage with my ADI-2/4 Pro SE. As soon as I can find a reliable source to make a purchase, I'm going for it.

 

Curvature

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You do have a point. Let me help you here.
- Measured electrical noise, does not directly equate to actual sonic noise out of a transducer. Consider this:
take two amplifers, both with noise-floors of -100dB, but one is 100W and the other is 1000W. If you measure the noise voltage of the two amplifiers, you will see that one is over 3X the other (+10dB)! plugged into same speakers, one can have audible noise, while the other may not.
Also, the bigger amp has 10dB more gain, which would amplify any noise fed into it.
Of course there are other factors, such as the ambient noise level, the sensitivity of the transducers, the frequency bandwidth of the noise, the sensitivity of the hearing of the person ...... So it is not set in stone or one size fits all, but I would say an electrical noise of at least -90dB, out of a 200W amp into a transducer of less than 92 dB for 1W (I chose some typical values) would yield an inaudible noise for most people/situations.
- However, in this particular case, the standard device has such a low noise floor (and we are talking noise-floor not SINAD) that any reduction by using the new PSU, is not going to tip the audibility of noise.
Agreed with you there.
 
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Sokel

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OK - here is the closest we have for a hypothesis on that here at ASR. So far no-one has disproved this, as far as I know, even for the lenient limits.

Audibility thresholds of amp and DAC measurements
Sorry,but to disprove something first it must be proven beyond doubt.
And the thread is just using a working hypothesis to built on it.

I asked once how the low freq uncorrelated noise (like the one introduced by bad EQ for example) sounds like and no one could describe it amongst pros.
They DO know how it sounds like,they just can't communicate it.
 

antcollinet

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Sorry,but to disprove something first it must be proven beyond doubt.
And the thread is just using a working hypothesis to built on it.

I asked once how the low freq uncorrelated noise (like the one introduced by bad EQ for example) sounds like and no one could describe it amongst pros.
They DO know how it sounds like,they just can't communicate it.
I thought science was about building a hypothesis and then testing it - especially attempting to disprove it.

Because you cannot prove something beyond doubt. And if you could, then attempting to disprove it would be stupid. Hypotheses for which there is sufficient evidence in support, and which have proven resistant to challenge become theories.

Scientific inquiry includes creating a hypothesis through inductive reasoning, testing it through experiments and statistical analysis, and adjusting or discarding the hypothesis based on the results

Rigorous scepticism requires us to attempt to disprove our hypotheses in an attempt to avoid biases

Or something like that. :p
 

Sokel

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What do you mean here? Can you post an example?
Like what we see in various threads,the ongoing problems (check their forum for older posts) with miniDSP for example (they applied a partial fix as a result of a thread here as well),or the Topping D50 III new one,or the Bluesound one,etc.
It's not like with a weak amp which resembles hum if you don't know the cause,that's easily describable ,it's the underlying "wrong" noise.

See,I can't communicate it either but you know it's there comparing with the one free of noise specially when levels go up.
It's a good practice with headphones.

Edit:typos
 
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markstein

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@Sokel: I recommend reading Karl Raimund Popper's thoughts about empirical falsification.
 
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