I wanted to create this thread to facilitate discussion about the Cozoy Astrapi DAC/amp, which is made by the same folks behind the Shozy Alien portable media player.
Cozoy's website is pretty sparse right now, but I sent a request to see if they offer review samples, and fortunately they said yes! So a big thank you needs to be given to them for letting me have this opportunity.
http://www.cozoyaudio.com/
The official specifications for the Astrapi:
3.5 mm TRS lineout for iPhone and supports up to DSD (DoP)
* Software support is required
< 10 g
Metal design
Thinnest place measures at 7 mm
Durable brushing and matte finishing
No need to charge, just plug and play
System power current: 10mA - 70mA max.
Power input: 1.8V-3.3V+-10%
Output gain level step: 3dB/step; 16 steps
* Output varies as power input may differ, this situation exists on every kind of OS
Native 16/44.1 decoding and implementation of DSP tuning algorithms
Multi-Platform Support: Works with iOS perfectly, Android (OTG required), PC/Mac with USB 2.0 port.
I'll start writing my review of the Astrapi here and I'll make an official product review when I complete the review here.
Box Contents
I literally just received this unit a yesterday and I got to unboxing it today. I created a silent unboxing video showing exactly what's in the box, but since I made it for ASMR purposes (and not everyone is into it or even knows what it is), I'll list the box contents directly.
Astrapi unit
1-year warranty card
3 ft. (~91 cm) USB 2.0 A-microUSB cable (black colour)
1 ft. (~30 cm) Apple Lightning-microUSB cable (white colour)
1 ft. (~30 cm) microUSB-microUSB Android USB OTG cable (white colour)
2:41 - Front of box
2:55 - Sides of box
3:11 - Back of box
9:12 - Opening the box
9:35 - Astrapi unit overview
9:45 - Shirt clip
10:00 - 3.5 mm headphone output jack
10:14 - microUSB input jack
11:08 - Warranty card
14:45 - Lightning-microUSB cable
15:44 - microUSB-microUSB cable
17:29 - USB A-microUSB cable
^ this thing is TINY!
What It Is
It's a USB DAC and amplifier for headphones. Unlike a typical portable DAC/amp that work with smartphones and other mobile devices, the Astrapi contains no battery and it relies on the attached device for power. This can be a good, or bad thing. It's good because it allows the Astrapi to take its extremely tiny form factor and lightweight construction, but it's bad because it relies on a noisy ground connection from the host device (e.g. your smartphone or other USB port).
That being said, with a microUSB port, and having a small power consumption requirement, that means the Astrapi can work with many devices without worrying about it being incompatible with things such as Apple iOS products, Android USB OTG-supported products, or even just as a USB DAC for your computer.
Information Regarding the DAC Section
The Astrapi is an unusual device. It only operates on a native 44.1 kHz sampling rate; no more, no less. However, it uses undisclosed digital signal processing (DSP) to allow playback of audio with sampling rates of up to 192 kHz (44.1, 88.2, 176.4, 48, 96, and 192 kHz can all be played back). If you use Windows, you can't use WASAPI output with the Astrapi because I believe WASAPI relies on asynchronous communication with the DAC and if you play a 16/48 music track, for example, the Astrapi can't operate on a 48 kHz sampling rate natively.
Windows output audio device settings
OS X Audio MIDI and Audirvana Plus device settings
In the screenshot above, you can see that the volume knob on the Audirvana Plus media player has a blue colour. Blue indicates that the volume is being controlled on the operating system/driver level, not the DAC level. This usually means that volume adjustments affect the sound quality and you lose bit resolution. I will get to this later below.
http://www.wiebel.nl/zut/Audirvana%20Plus%20User%20Manual.pdf
Digital (blue cursor): typically digital volume control at the device driver level, so still in the computer, with potential associated resolution loss. Should typically be set at 0dB to ensure bit perfect output.
Setup of the Astrapi is also kind of weird for use as a USB DAC/amp with a computer. Firstly, if you restart your computer, you have to unplug/replug the Astrapi or else it won't be recognised by the operating system (I tested this on Windows 8.1 and OS X Mavericks). Secondly, when you replug the Astrapi, it takes around 10 seconds for it to actually be recognised. I'm not sure what kind of handshake the Astrapi does with the computer interface, but when I plugged it into Windows for the first time, there were two device/driver setup processes being run and they took around a minute to finish installing.
DSD via DSD over PCM (DoP) is also supported, but when I tried to play a DSD64 track in Foobar in Windows (you can get some free DSD tracks from OPPO Digital's website here), I had to convert it to PCM because ASIO drivers are not available for regular DSD via DoP playback.
For Android and iOS devices, the Onkyo HF Player application can be used to play DSD via DoP. Unfortunately at this time, I don't have a way to connect my iPhone 4S (which uses the legacy 30-pin connector) to try this out, but I'll trust Astrapi's words that it's supported.
https://itunes.apple.com/us/app/onkyo-hf-player/id704139896?mt=8
https://play.google.com/store/apps/details?id=com.onkyo.jp.musicplayer
Contrary to what twister6 and Baycode reported in their reviews, the Astrapi unit I have works perfectly fine out of my Retina MacBook Pro's USB 3.0 ports, both in Windows 8.1 and OS X Mavericks.
At maximum volume, and thus system volume according to the Audirvana Plus user manual, the 3.5 mm output jack acts as a line-out output, so you can connect it to an external amplifier. With the system volume being set to maximum, the Astrapi's DAC would be receiving a bit-perfect signal and is the best way to provide an accurate signal for the next component of the audio chain (amplifier).
Information Regarding the Amplifier Section
On to the amplifier section. I do not know how the amplifier works on the Astrapi exactly. From the above specifications, it says the Astrapi has a +3 dB gain per volume step/increment and there are 16 increments in all iDevice and Mac OS X computers. Total, that makes the maximum output gain +48 dB. Keep in mind that gain is not necessarily the same as power, and Cozoy has the disclaimers:
output varies as power input may differ, this situation exists on every kind of OS
...
The device is designed for iPhone users, other Apple device may have a different vol. output level. Old [30]pin devices are NOT supported. You may need to buy a [30]pin to Lightning adaptor to use this product.
Different devices output different amounts of power (voltage and current) to the Astrapi. Because of this, the actual power output to the headphone varies.
In any case, this device has a TON of gain for my headphones. In OS X, volume 1/16 is plenty loud for my AKG K 701. For my MEElectronics M9, there is so much gain with the Astrapi that I have to manually adjust the volume in the Audio MIDI application to volume levels below which I can't usually adjust to with the OS's volume slider nor keyboard media keys.
That volume level is 0.003. Mac OS X Snow Leopard can't even get that low, the lowest being 0.01.
While using the Astrapi as a USB DAC/amp with your computer, I would not recommend using sensitive in-ear earphones with it because of how severely limited the volume control is. Also, with the M9s, I can hear background hiss through the Astrapi. Like with many USB-powered DAC/amps, the amount of noise is dependent on the host device so your mileage may vary, hence why I mentioned it being a bad thing in the "What it Is" section. For instance, I can hear more background hiss when the Astrapi is connected to my 2008 MacBook versus my 2012 MacBook Pro. I've been using the same USB A-microUSB cable for these tests and it has a ferrite bead attached to it for some noise rejection.
I don't think the Astrapi has any sort of protective relay built into it, so when you disconnect the USB input and you have the headphones connected, it makes a pretty loud "pop" sound even with my K 701. A similar event happens when I plug in the headphones sometimes. Slightly worrisome, but I don't think it's a big problem.
How it Sounds
*Note this is still a work in progress*
I've given the Astrapi a few hours of burn-in without listening to it, so you guys can't give me flack about it while I'm writing these sonic impressions. : p
I honestly didn't really know what to expect from the Astrapi because of its size. To me, it sounds pretty good and its ~$130 street price is reasonable in my opinion. I'm used to the sound coming from the LH Labs Geek Out and OPPO HA-2; the former of which is a USB DAC/amp for your computer, the latter is a USB DAC/amp meant to be paired with smartphones much like the Astrapi.
Used as a computer USB DAC/amp with the AKG K 701:
Talking about the Astrapi by itself, it has good detail retrieval and a slight warm lower-midrange/upper-bass area. This is pleasant to listen to and it gives music some nice energy and a sense of strong dynamics. Another thing I liked in particular was the size of the soundstage and sense of space around my head, specifically the height and width. Listening to choral music recorded in a church really makes the size of the soundstage apparent.
Is the Astrapi's sound perfect? Although we all wish everything was perfect, of course it's not. One thing I noted immediately was that the upper-midrange and treble sounded pretty grainy on the other hand, almost too textured and detailed, and it comes across as being aggressive-sounding to me. This is my number one complaint about the sound: it's a bit too strident-sounding for me.
Although I liked the Astrapi's ability to produce good width and height in the soundstage, it sounds limited in depth to me. Because of this, imaging isn't quite accurate. I have a collection of self-recorded binaural recordings and I know exactly where the microphones were placed relative to certain sounds. The Astrapi makes instruments seem closer to me and more spread out horizontally than they were while recording.
For the purposes of comparisons, I find the OPPO HA-2 to sound pretty close to the LH Labs Geek Out, with the Geek Out having a smoother-sounding treble and the HA-2 with slightly more upper-bass/lower-midrange warmth. The Astrapi offers a different sound signature from either device from my listening tests, having less depth in the soundstage and a more aggressive-sounding upper-midrange/treble tuning. In terms of sound, I don't think the Astrapi can be fairly compared to the GO and HA-2, but at its price point, I think it sounds reasonably good.
I'll have to update this portion of my review at a later time when I get a chance to use the Astrapi with iDevices and/or Android devices, so stay tuned for that.
Thanks! I actually have to wonder how the Stoner Acoustics UD100 would compare to the Astrapi in terms of sound. They're both around the same price bracket, but of course the Astrapi works right out of the box with iOS devices and Android.
Thanks! I actually have to wonder how the Stoner Acoustics UD100 would compare to the Astrapi in terms of sound. They're both around the same price bracket, but of course the Astrapi works right out of the box with iOS devices and Android.
I wonder how the Astrapi performs objectively. I just saw that the UD120 uses a minimum phase digital reconstruction filter; pretty interesting to see happen in an inexpensive device like that.
I'll try out the Astrapi as DAC with the line-out feature tomorrow with my STAX setup. I was going to do it today but I got caught up on other things. I still find it strange that the Astrapi uses the operating system to control the volume, and it operates at 16-bit resolution natively. I'd imagine the sound quality via line-out will be better because of that.
Right now it's still technically in the pre-ordering phase, so not a lot of people have heard it. I personally haven't heard the Shozy Alien before, although I'd like to some day since I've read a lot of positive things about how it sounds.
[rule]
I tried out the Astrapi with my STAX setup using the line-out connection (100% software volume) and it sounds pretty good overall! The slight harshness is still present in the upper-mids area, but I think the graininess is toned down a bit.
Right now I'm using it as a USB soundcard with the OPPO PM-3 and it sounds pretty good to me too. I'd say this setup has much better synergy compared to the K 701. However, like what I mentioned about in-ear earphones, the Astrapi has waaaaaaaaay too much gain. The useable volume range is really limited for me in this setup and right now 1/4 of 1/16 volume, or volume 1/64, on OS X is pretty much as loud as I would ever use it. I have to use Audio MIDI once again to tune the volume any lower because the media keys simply don't have a fine enough adjustment.
Thanks! I actually have to wonder how the Stoner Acoustics UD100 would compare to the Astrapi in terms of sound. They're both around the same price bracket, but of course the Astrapi works right out of the box with iOS devices and Android.
First of all thanks for the great write up and creating this thread!
I've the UD110 and have compared these 2 together. Personally I think the the Astrapi is a much more enjoyable listen and is more usable. The Astrapi to my ears is warmer and more spacious that the UD110, the UD110 being a much more flat and dry sounding. The UD110 has something like 440Ohms of output impedance which is a huge disadvantage. This means that the UD110 cannot really be used as a single unit, and to get the most out of it, you would need to pair it with a separate amplifier. The Astrapi is the opposite. It has low output impedance and has a surprising amount of oomph. The power output relies primarily on the source device; I have mine plugged into a power USB hub which has an output current of 1A, meaning it get a lot more efficient in amplification. Using it with my phone, it is still pretty powerful (maybe about 50%), having enough power to drive my 60 Ohm cans, something that the UD110 cannot do at normal listening levels.
Right now it's still technically in the pre-ordering phase, so not a lot of people have heard it. I personally haven't heard the Shozy Alien before, although I'd like to some day since I've read a lot of positive things about how it sounds.
I tried out the Astrapi with my STAX setup using the line-out connection (100% software volume) and it sounds pretty good overall! The slight harshness is still present in the upper-mids area, but I think the graininess is toned down a bit.
Right now I'm using it as a USB soundcard with the OPPO PM-3 and it sounds pretty good to me too. I'd say this setup has much better synergy compared to the K 701. However, like what I mentioned about in-ear earphones, the Astrapi has waaaaaaaaay too much gain. The useable volume range is really limited for me in this setup and right now 1/4 of 1/16 volume, or volume 1/64, on OS X is pretty much as loud as I would ever use it. I have to use Audio MIDI once again to tune the volume any lower because the media keys simply don't have a fine enough adjustment.
First of all thanks for the great write up and creating this thread!
I've the UD110 and have compared these 2 together. Personally I think the the Astrapi is a much more enjoyable listen and is more usable. The Astrapi to my ears is warmer and more spacious that the UD110, the UD110 being a much more flat and dry sounding. The UD110 has something like 440Ohms of output impedance which is a huge disadvantage. This means that the UD110 cannot really be used as a single unit, and to get the most out of it, you would need to pair it with a separate amplifier. The Astrapi is the opposite. It has low output impedance and has a surprising amount of oomph. The power output relies primarily on the source device; I have mine plugged into a power USB hub which has an output current of 1A, meaning it get a lot more efficient in amplification. Using it with my phone, it is still pretty powerful (maybe about 50%), having enough power to drive my 60 Ohm cans, something that the UD110 cannot do at normal listening levels.
I haven't gotten a hold of a good USB hub yet. I really have to test the power of the Astrapi with well, more power! Did you just take a y-cable micro-usb cable to make this work properly?
First of all thanks for the great write up and creating this thread!
I've the UD110 and have compared these 2 together. Personally I think the the Astrapi is a much more enjoyable listen and is more usable. The Astrapi to my ears is warmer and more spacious that the UD110, the UD110 being a much more flat and dry sounding. The UD110 has something like 440Ohms of output impedance which is a huge disadvantage. This means that the UD110 cannot really be used as a single unit, and to get the most out of it, you would need to pair it with a separate amplifier. The Astrapi is the opposite. It has low output impedance and has a surprising amount of oomph. The power output relies primarily on the source device; I have mine plugged into a power USB hub which has an output current of 1A, meaning it get a lot more efficient in amplification. Using it with my phone, it is still pretty powerful (maybe about 50%), having enough power to drive my 60 Ohm cans, something that the UD110 cannot do at normal listening levels.
Sure thing! I figured I'd create this thread since there's not really a dedicated impressions thread for the Astrapi yet.
Do you know what the output impedance is for the Astrapi? I don't think I've seen any numbers for it yet.
As for power, I'm not sure what the output numbers are. I know gain is specified, but that's not necessarily equivalent to power output. I think for a desktop setup, the Astrapi has way too much gain for sensitive portable and/or in-ear earphones. I've been using the Astrapi with the PM-3 (great sound synergy), but the "volume range" is extremely limited with the setup (1/64 volume in OS X is too loud for me for 90% of my headphone requirements, and volume 2/100 is about the volume I use in Windows 8.1).
I personally haven't tried it yet (hopefully I will in the near future), but I'm guessing for a mobile device rig, the Astrapi's volume management is much better.
"However, it uses undisclosed digital signal processing (DSP) to allow playback of audio with sampling rates of up to 192 kHz (44.1, 88.2, 176.4, 48, 96, and 192 kHz can all be played back)."
Downsampling to 44.1 is undisclosed digital signal processing?
I haven't gotten a hold of a good USB hub yet. I really have to test the power of the Astrapi with well, more power! Did you just take a y-cable micro-usb cable to make this work properly?
Sure thing! I figured I'd create this thread since there's not really a dedicated impressions thread for the Astrapi yet.
Do you know what the output impedance is for the Astrapi? I don't think I've seen any numbers for it yet.
As for power, I'm not sure what the output numbers are. I know gain is specified, but that's not necessarily equivalent to power output. I think for a desktop setup, the Astrapi has way too much gain for sensitive portable and/or in-ear earphones. I've been using the Astrapi with the PM-3 (great sound synergy), but the "volume range" is extremely limited with the setup (1/64 volume in OS X is too loud for me for 90% of my headphone requirements, and volume 2/100 is about the volume I use in Windows 8.1).
I personally haven't tried it yet (hopefully I will in the near future), but I'm guessing for a mobile device rig, the Astrapi's volume management is much better.
Yup I probably have around 150 hours or so after using it with the PM-3 for the last week. It sounds about the same to me after all this time. XD
Nothing official but I'm expecting it to be something like 2 Ohms or less. For the 10mW-70mW of output it has to be very low.
This page has a lot of the specs you don't get anywhere: http://penonaudio.com/COZOY-DAC-AMP
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