USB Standard and Ports

For a complete history and explanation of USB standard (1.0, 2.0, 3.0, 3.1) and port types (A, B, C, micro, etc), refer to Wikipedia USB article.

NuPrime communicates and decode digital music from the computer through USB Audio (this is a software standard, not physical USB standard). USB Audio is a software standard that defines how audio devices can communicate with the computer to play music. The USB standard and port type set the physical properties of how devices are to be connected to the computer and the speed limit.

The USB communication is always between a host and a client devices. Some devices such as smartphone or tablet can act as USB host or client device. When a smartphone is connected to the computer, it functions as a client device to the computer. Printer and USB hard drive are USB client devices. Client devices can not work with each other, unless one of the device has the capability to become a host. NuPrime's DACs (including Digital Integrated Amp) are all USB client devices and they are designed to play music from computer, smartphone or tablet. 

Some of the NuPrime models come with two Type-A ports. One of the ports is a standard USB 2.0 port (for audio, USB 2.0 is the standard and USB 3.0 is backward compatible with USB 2.0) for USB audio use. The other port is a proprietary NuPrime digital port that uses the same USB Type-A connector. It is not a USB standard! NuPrime wireless devices (Bluetooth dongle, WiFi audio receiver) use this custom digital port for 5V power as well as digital music signals (in S/PDIF format). For example, if NuPrime WR-100 is to be connected with a non NuPrime DAC, it would have to be powered by a 5V power adapter and connect its optical S/PDIF output to the DAC. But if WR-100 is connected to NuPrime IDA-8 or DAC-9, a single cable is all that is needed.

USB 3.0/3.1 is also compatible with USB Type-C, the latest plug design that’s just starting to gain adoption. This reversible plug is distinct from USB 3.1, though manufacturers may choose to support both at once. For example, the 2015 MacBook and the second-gen Chromebook support the USB 3.1 standard on their Type-C ports, while the OnePlus 2 uses the USB 2.0 standard despite a Type-C port. Don't confuse the USB standard with the port type. 

What is the difference between Pure Direct, Pure Audio, and USB Audio?

Pure Direct and Pure Audio modes are part of the multi-channel mode and utilize the high quality multi-channel DAC. USB Audio goes through a separate high performance stereo DAC board. 

Pure Audio is a 2-channel Stereo mode where multi-channel inputs from the source are converted to 2 channel audio. Pure Direct is a pass-through (from the source device such as BluRay player) mode without any EQ effect. 

Don't confuse Pure Audio or Pure Direct with USB Audio input. If you have a computer connected to HD-AVP through USB Audio, by selecting the USB Audio as input source you will be utilising the high-end stereo DAC (this USB Audio DAC has the same performance as NuPrime DAC-10) instead of the multi-channel DAC for surround sound decoding.

The L&R outputs from 7.1 outputs come from USB DAC outputs or AVP outputs. The USB L&R outputs come only from the USB DAC.  That means if you are using USB Audio as the input, there are two sets of outputs: L&R outputs from 7.1 outputs and USB L&R outputs. This allow you to setup a separate high-end stereo system in another room. Therefore, if you select USB Input as the source, then the USB DAC outputs go to 7.1 L&R RCA and XLR and USB L&R outputs.

What is USB Audio and how do I configure Windows or Mac computer for USB audio and the DAC ?

USB Audio is a standard for digital audio used in PCs, smart phones and tablets to interface with audio peripherals. The source device that produces the data is called the USB Host and the receiving end is the USB Client. So, if a smartphone is connected to a computer, the computer is the host and the phone is a client. But if a DAC is connected to the smartphone, then the phone is now the host and the DAC is the client.

Most USB audio interfaces are USB 1.0 and USB 2.0 compatible, so you should have no problem getting a device to work with any computer manufactured in the last 5 years. A USB audio interface attaches to the computer with a standard USB connector and to the device itself with any number of other connectors, ranging from proprietary connections to standardized connections.

USB Audio devices do not need the bandwidth of USB3.0 and USB3.0 is backward compatible with USB2.0

USB 2.0 can handle bandwidth of 480 MB/second. To put this into perspective, 24 bit/192 khz audio--the highest bandwidth in commercial use--uses approximately 10 MB/second per track of audio. So, a stereo recording would take approximately 20 MB/second or 5 percent of the possible USB 2.0 bandwidth. This large amount of bandwidth available allows for USB audio interfaces to accommodate just about any recording or playback scenario imaginable.

Steps to setup your computer to use external USB Audio device such as a DAC (Digital to Analog Converter):

  1. Connect the USB Audio device to the computer (before installing any device driver).
  2. Install the Windows device driver if it is required (Mac computer does not need to install USB Audio device driver)
  3. Go to the System Preference/Setup and look for Sound device setup. Choose the desire USB Audio device (e.g. NuPrime uDSD, Encore mDSD, ...)

For further information about how to configure the music player software for high resolution music playback, download this user guide: http://www.nuprimeaudio.com/images/productpage/NuPrime-USB-Playback-Guide.pdf

Occasionally Windows users might encounter driver error or not able to install certain device driver files. This is usually due to conflict with previously installed driver. Unfortunately there is no simple solution to this problem. Try the following steps:

  1. Uninstall NuPrime USB audio device driver.
  2. Go to Device Manager and look for any USB audio device driver (or any device driver) that has an error mark next to it.
  3. Delete the driver.
  4. Install NuPrime USB audio device driver again.

What kind of volume control and preamp do you use for your DAC?

In traditional pure-analog designs, a switch-resistor network for volume control works best but is very expensive due to the use of many high precision discrete resistors. Next is a high-quality volume pot. You rotate the pot to change resistance, which in turn attenuates volume. A volume pot is non-linear and has balance issues at low volume.

A DAC typically has a mix of analog and digital inputs. Some DACs convert the analog input into digital to utilize the DAC's internal digital volume control and inputs selection, avoiding the use of expensive analog preamp and volume control as described above. The performance degradation of the analog input that has to go through A2D, volume adjustment and then D2A depends on implementation, which is beyond the scope of this discussion. Digital inputs on the other hand should go through the high-end DAC's internal volume control for best performance. 

Therefore it make sense to best adjust the volume in the digital domain for digital signals, and use an analog preamp and volume control for analog inputs.

Our DAC-9 and DAC-10* have analog inputs without A-to-D conversion. We use a mixed analog and digital volume-control design. The digital volume control’s 0.5db steps are sent to the DAC for the best possible result. The DAC’s analog output and analog inputs from other sources then go through a switch-resistor network. The DAC's output is switched straight through with minimum resistance. For analog inputs, the switch resistor network provides the best possible result. 

In conclusion, we feel we’ve developed the best type of volume control and preamp for a modern DAC.

How do I connect my DAC to Android or iOS tablet and smartphone?

If you are not familiar with USB audio device, please read the FAQ topics on "What is USB Audio and how do I configure Windows or Mac computer for USB audio and the DAC ?" and "USB Standard and Ports"

The standard USB audio cable that comes with your iOS or Android device can not be used to connect the DAC. You will need a different cable that treat the iOS or Android device as the host, and the DAC as the client. 

  • iOS device - use a genuine or Apple MFI approved USB Camera Adapter cable
  • Android device - use a quality USB OTG cable

iOS Device

USB Audio has always been supported by iOS. You can use Apple USB Camera Adapters to import photos from your digital camera. You can also use Apple USB Camera Adapters to connect other USB devices to your iPhone, iPad, or iPod touch. If you're using an Apple USB 3 Camera Adapter, you need an iPad with iOS 9.3.

Some USB devices need more power than your iPhone, iPad, or iPod touch can provide. If you connect one of these types of USB devices, you might see an alert that says “attached accessory uses too much power." Try one of these steps: 

  • Connect the USB devices to a powered USB hub or secondary power source.
  • Use a Lightning to USB 3 Camera Adapter. The Lightning to USB 3 Camera Adapter has a built-in lightning port, which you can connect to a USB power adapter. This provides power to your iOS device and connected USB device.

Android Device

Prior to version 5.0, the support for USB audio is spotty. Some device manufacturers do a better job than others. In general, Android OS 4.1 and above provide support for USB audio device. If you have doubt, check with your device manufacturer or search for help online. Please do not ask our support staff. In general, similar to iOS device, if the DAC is connected and functioning properly, the Android OS will send the audio to the USB port. There is no need for any system configuration.

We strongly recommend USB Audio Player PRO for high resolution music playback.

Similar to iOS device, if your USB device consumes more power than allowed by Android device, you will need to power the USB device. If you are technically inclined, here's a useful article: http://source.android.com/devices/audio/usb.html

Powered USB DAC

NuPrime DAC-10/10H, DAC-9, IDA-16, IDA-8

Externally Powered USB DAC

  • NuPrime uDSD - should always be connected to computer or a powered USB hub
  • Encore mDSD - can be connected to mobile iOS or Android devices directly, provided that the headphones used do not draw too much power. mDSD should be connected to headphone before connecting to the mobile device. If you don’t hear any sound from iPhone or iPad, try to lower your iDevice system volume, then pressing the mDSD volume up first, then increase the system volume.

How to connect to a powered USB hub - you will need a USB Type A to Type A cable for connecting the Android USB OTG Cable or Apple Camera Adapter Cable to the USB hub.

 

What some of the amps have the same power rating at 8 and 4 Ohms ?

There is two side to a coin. The truth is that the amp is capable of more power than the spec suggested. So if 4 and 8 Ohms are specified at 100Wx2, that means the power supply is a 200W PSU. And we are extremely conservative about our power rating (we provide conservative RMS rating, not peak power). A customer reported 180W for IDA-8 because he is using just one channel to do the measurement. So, if IDA-8 is in a bigger case, and we put in a 300W PSU, you will see a higher rating. In reality, you get more than 100W per channel from the 200W PSU, because not both channels are driven at the same time.

Why don't we put in a bigger PSU? Each model is designed for specific product position and adding more power will certainly increase the cost and size of the product.