Sbooster's Technical Frequently Asked Questions:
- Does a BOTW P&PECO power supply have a lot of AC-leakage current?
AC leakage current is (unwanted) current, that flows from either AC or DC circuits in equipment to the chassis or to the ground and can be either from the input or the output.
The actual question is whether there is unwanted AC voltage/current at the DC output of the BOTW P&P ECO power supply caused by this leakage current.
The BOTW P&P ECO is a linear power supply and because of its design the negative effects of this AC leakage current is negligible.
SMPS (switch-mode power supply/-ies) generate a high leakage current with voltage spikes > 300V AC on the output. This is caused by two capacitors that are internally connected between the Hot/Neutral and output of a SMPS.
Linear power supplies are equipped with a transformer. A transformer has a small amount of self-capacity between the primary (AC input) and secondary (AC output) windings. The amount of capacity depends on the type and construction of the transformer, but the capacity is much lower, than the value of the capacitors installed in a SMPS power supply. Therefor the negative effects of the AC leakage on the output of a linear power supply can be very small.
ââ¬â¹There are a couple of ways to reduce or eliminate the AC voltage/current at the output of a linear power supply even further. The most common options are:
For many decades it has or has been good practice to connect the negative output/rail/plane of a linear power supply to the (PE) Protected Earth. With this connection the AC current on the output is directly shorted to Earth and removed from the output of the power supply.
We do not use this connection in our BOTW P&P ECO power supplies, because it increases the risk of equipment failure/damage due to ESD (Electrostatic Discharge), when the power supply is used in an audio chain where also SMPS are used.
Please see our White Paper “Risk of ESD” for more information; https://www.sbooster.com/white-paper-esd
Using a transformer with electrostatic shielding: We use this option in our BOTW P&P ECO power supply range. The electrostatic shielding is a copper foil that is installed between the primary and secondary windings and is connected to the (PE) Protected Earth. The foil creates a low impedance return pad for the AC leakage and ensures that this AC leakage is not passed on to the AC output of the transformer, thus the DC output of the BOTW P&P ECO. To prevent unwanted noise injection from a polluted Earth line into the electrostatic shielding, we have equipped our mains filters with an additional Earth line filter arrangement.
For those who are interested: on Audio Science Review- forum the effect of AC leakage current has been measured with a LPS-1/SMPS (Meanwell power supply) and LPS-1/BOTW P&P ECO combination.
The higher the power rating (the amount of Watts), the better the power supply…
Sorry, but not true!
There is no relation between the output rating of a power supply and the sound quality improvement you will get from a power supply. The sound quality improvement of an audio grade power supply depends on multiple factors from the power supply design. In general high rated linear power supplies, which are only used for a very small load, have a very poor efficiency. This will result in an unnecessary waste of energy. The energy waste over 5 years from a (i.e.) 5 x overrated power supply can be as high as the purchase price of a more efficient power supply, which is i.e. only 2 x overrated.
ââ¬â¹When selecting a proper power supply two things are important:
the output voltage of the power supply has to match the input specification of a device.
the output current rating: this has to be equal or a bit more, say 2x more, than the specification of the device.
To determine the correct power rating of a power supply you have to check the actual power consumption figures of a device, not the rating of the stock supplied SMPS adapter. I.e. if the maximum power consumption of a device is 15W and the required Voltage is 12V, a 12V - 1.25A power supply would be sufficient, but for an audio grade power supply 2 to 3A would be advisable.
My device is not in the compatibility list. The stock supplied power supply rates 12V/4A. The BOTW P&P ECO 12-13V has a rating of 12V/3A. Can I still use the BOTW P&P ECO for my device?
There is a big difference between SMPS and the BOTW P&P ECO when it comes to specifications and performance.
A SMPS can only deliver the maximum current that is specified on the power supply label. In other words, a SMPS has no power reserve / no head room. When a device demands more current than specified, the SMPS cannot supply this current and becomes unstable. This can result in not booting of the device or shutting down of the device during operation.
Since peak loads generate the highest current demand, a designer of a device has to select a SMPS based on this peak-load figure. In 95% of the cases where we check the actual power consumption of an audio device, we measure an average current that is only 35 – 40% of the maximum SMPS rating.
When the power rating of a SMPS is 4A we know for 100% sure that a peak load simply cannot exceed this 4A, otherwise the stock supplied SMPS would be too small and the device would not work (properly).
Unlike a SMPS (and many other power supplies for that matter) the power rating on the label of the BOTW P&P ECO power supplies is the maximum continuous output current rating, not the maximum peak load current nor the maximum output limit. The peak load capability is not specified on the label. However due to the split-current system the BOTW P&P ECO stays stable and in regulation even with peak loads of 150-200% of the maximum continuous output current rating. In other words, a BOTW P&P ECO power supply has sufficient power reserve/ head room to handle peak loads.
So i.e. if a DAC has an actual power consumption 25Watt and the stock supplied SMPS has a power rating of 12V/4A, the BOTW P&P ECO 12-13V will fit easily.
Note: Peak loads are high frequency events and can only be measured with an Oscilloscope. Our Sbooster I-know nor a low cost digital multi-meter is capable of measuring these values.
What is the power rating of the Ultra?
The power rating of all available Ultra with their matching BOTW P&P ECO and correct DC output Voltage setting is 850mA average and 1100mA peak.
- Can I power two devices with one BOTW P&P ECO?
The BOTW P&P ECO is capable of providing power to two low power consuming devices, but we do not advice this, because of possible interference between the two outputs. In addition when a single power supply / single power rail is connected to two devices and when these devices are also connected i.e. via LAN or USB, a high ground current can start to flow between the two devices. In case the devices are connected via USB, equipment can be damaged when the total ground current exceeds the maximum allowed current for a USB-connection.
Further, a single power supply for every audio device leads to a higher sound quality compared to a multiple output version (unless all outputs have their own individual and isolated power rails).
- Can you manufacture a power supply that has adjustable Voltages i.e. 5V to 19V?
Technically we could, but we will not. Here is the reason why:
A linear power supply with adjustable output Voltages is – especially at the lower Voltages - a very inefficient power supply. When the power supply can be adjusted from 12V to 5V, this means that the transformer has to be large enough, that the power supply outputs at least 12VDC. The efficiency of a 12V linear power supply is in average about 60%.
So in example: when the load is 1A, the AC-power (the power that is needed from the mains) will be (12Vx1A)/0.6 = 20W AC-power. When the load remains 1A and the Voltage is switched from 12V to 5V, the AC-power remains 20 W, but the output is 5Vx1A= 5W instead 12Vx1A=12W.
The effect on the efficiency is that the power supply at 5V/1A has an efficiency of only 25% (=5W/20W) In other words, 75% of the needed power to make 5V/1A is wasted. The dissipated energy is converted into heat and your energy bill is that high, that you could have dedicated 5V power supply for free in just a few years.
Would it be better to plug the BOTW P&P ECO into the power conditioner/filter or straight into the wall?
The BOTW power supply and a mains power conditioner/filter can work together. The combination can result in a very low overall noise floor and maximum sound quality improvement.
However, since the BOTW P&P ECO is equipped with a dual stage mains filter and an earth-line choke, the double filtering can be too much and negatively affect the music reproduction. The music loses its dynamics and become dull. If that is the case, then the two devices are no match.
Also, the fuse of the power supply can blow, when the BOTW P&P ECO is connected to a mains filter or a power strip with build-in filtering. Connecting the BOTW P&P ECO to an external mains filter can cause oscillation between the build-in filter of the BOTW and the external mains filter causing high voltage spikes.
Plugging the BOTW P&P ECO straight into the wall is then the best solution.
- Does the BOTW P&P ECO power supply pollute the mains like a SMPS?
The BOTW P&P ECO design has been tested on this subject for several approvals like FCC, CE-EMC, KC-EMC for the “Power line conducted emission”. The average emission of a BOTW P&P ECO is 5-7dBuV up-to 18Mhz, which is negligible.
- What is the ripple Voltage and Voltage accuracy of the combination of a BOTW P&P ECO power supply and Sbooster Ultra add-on?
The output voltage of the BOTW P&P ECO is accurate within 25mV from no-load to full-load when measured directly at the output terminals inside the power supply. When measured at the DC plug, the DC output cable and split-current electronics create a Voltage drop of 40 to 50mV @ 1A.
The 100 - 120Hz ripple of the BOTW P&P ECO is less than 1mV @ full load. The smaller the load the smaller the ripple Voltage.
One of the added values of the Ultra is that the unit filters the ripple with > 80dB, so the ripple will be reduced to only a couple of uV. Further the Voltage regulation circuit of the Ultra is even more accurate than the regulation circuit of the BOTW P&P ECO, but the highest improvement is made by the short output cable of the Ultra unit. This cable is that short that there is barely any voltage drop, which results in a maximum Voltage accuracy.
- What are the benefits of a BOTW P&P ECO power supply for my DC-turntable and phono stage?
The use of a BOTW P&P ECO instead of an SMPS for a DC-turntable has 4 benefits.
A SMPS by design creates a HF electromagnetic field. A turntable cartridge is equipped with a coil. The HF electromagnetic field of the SMPS radiates into the coil and causes electromagnetic interference (EMI), which leads to an unwanted electrical current flowing in the coil.
HF interference needs not much energy to be reproduced and thus to be audible. Replacing the SMPS by a BOTW P&P ECO eliminates this HF electromagnetic field. The BOTW P&P ECO has no negative effects of it on the cartridge.
Also by design a SMPS creates HF noise. The signal of a turntable is a small low Voltage signal, which is hugely amplified to be audible. Therefor every interference or deviation in the signal path will heard and must be prevented.
The stable and clean power of the BOTW P&P ECO enhances the performance of the motor electronics of the turntable. This results in increased accuracy of the RPM.
Last but not least, turntables need phono pre-amplifiers to amplify the small signal of the cartridge. If such a device is powered by a SMPS, the HF noise will be injected in the signal. The SMPS will lead to a sound quality degradation.
- Why should I buy such a large and “costly” power supply to upgrade my small and inexpensive device, like my switch or Raspberry Pi?
Usually the electronic design and used electronics of a small and/or inexpensive devices are quite nice, but your device is small and inexpensive due to the lack of a good power supply. Manufacturers of audio/video devices choose to supply their product with a low quality SMPS for the following reasons:
- a SMPS is cheap, millions of SMPSs are manufactured in China annually;
- a SMPS is suitable for worldwide use (100VAC – 240VAC)
- usually SMPS has safety approvals;
Should a manufacturer choose for a build in power supply, than the device would be larger and more expensive.
Now the manufacturer actually gives you the choice: are you satisfied with your product as it is, then you have the benefit that your product is inexpensive. As said above, usually the electronic design and used electronics of a small and/or inexpensive devices are quite nice. So should you wish for a better performance of your device, then invest in an external power supply like our BOTW P&P ECO and enjoy the full potential of your device.
- What is the fuse rating of the BOTW P&P ECO?
The BOTW P&P ECO power supplies are equipped with certified audio purpose fuses.
Some customers wish to change the fuse for an audio grade fuse. The fuse size is 5x20mm and the ratings are:
- Length of the DC-output cable is too short for the audio rack. Do you provide longer cables?
The length of DC output cable of the BOTW is selected with care to achieve a maximum performance. Increasing the length might reduce the sound quality due to the degraded stability of the supplied power to a device. Therefor we do not recommend to use an DC extension cable with the BOTW P&P ECO power supply.
The length of the DC-output cable including the Split-current unit is +/- 95cm.
- What are the weight and dimension of the BOTW P&P ECO MKII?
The dimension and weight excl. packaging is about: 24x13x7,5 cm / 1.85Kg
The dimension and weight incl. packaging and mains cable, is about 34x20x9cm / 2,3kg.
- What are the phase and polarity of the BOTW P&P ECO power supply?
- Electrostatic Discharge (ESD):
Can I just unplug the DC-plug from the audio-device?
No, you cannot unplug the DC plug from your audio device when the power supply is connected to the mains or is still turned “ON”. Pulling the DC plug might lead to a high voltage spike which can damage the electronics of your device.
Can I swap the cables of my audio equipment without disconnecting the SMPS from the mains first?
No, this can lead to damage of your equipment. Please read our white paper on the danger of ESD.
Can I just swap the Vbus2 Isolator or any (USB-)cable for that matter?
No, see above.
- The mains Voltage in my house is much higher/lower than the standard mains Voltage in my country. Do I have to set the BOTW P&P ECO to another mains Voltage setting?
The BOTW P&P ECO will be standard be set according to the official mains voltage specifications of the country of the delivery: https://en.wikipedia.org/wiki/Mains_electricity_by_country
The BOTW P&P ECO automatically corrects the mains voltage with at least +/- 5%.
This means that a BOTW P&P ECO with a mains Voltage setting set on 230V will function for 100% with an actual mains voltage between 218 – 240V AC.
When you are in doubt about your mains Voltage setting, please contact us.
- How to get the maximum sound quality out of a streaming device?
If your goal is to achieve the maximum sound quality out of a streaming audio device, then in general you have to meet following requirements:
- Keep the power consumption of the streaming device as low as possible;
- Reduce processor task to a bare minimum;
- Avoid noisy devices like internal/external hard disk drives;
- Use the best power supply solution as possible;
- Stream Music from LAN connected sources like a NAS or streaming services like Tidal, Qobuz etc.;
- Optimize your LAN with at least a high quality powered Switch close to your playback device;
- Disable WIFI in the OS or better, remove the (noisy & unnecessary power consuming) WIFI adapter completely.
Should your question and answer not be in the above? Please do not hesitate to contact us.
Sbooster, enjoy more music.............