[miceblue]

"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?

If it only downsampled to 44.1 kHz, that would imply that 192+ kHz sampling rate music files would work with the Astrapi, which they don't.

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

States that 100% volume activates line-out mode.

Ah I see. I didn't see those specifications earlier. That actually mentions current output, not power output.

Output vrms:1.5Vrms max
System power current :10mA-70mA max

1.5 Vrms would translate to 140.62 mW of power into a 16-ohm load. However, it seems the Astrapi is current limited (140.62 mW would require 90 mA of current), so the actual power output at 16 ohms would be less.

The Astrapi delivers maximum current and maximum voltage into a 21.4-ohm load with 105 mW output.

The Astrapi delivers the minimum current and maximum voltage into a 150-ohm load with 15 mW output.


As I mentioned in the second post, the volume seems to be attenuated on the operating system level, which means anything less than 100% volume output would input a not-bit-perfect signal into the DAC section. This volume control is implemented similarly to the Objective DAC. Ideally the operating system volume level should be 100% if you want a better signal going into the amplifier section, yes, so it makes sense that 100% volume on the Astrapi would "activate" a line-out mode. It's more like a line-out plus pre-amp since it also has +_ gain.

 

[DJScope]

If it only downsampled to 44.1 kHz, that would imply that 192+ kHz sampling rate music files would work with the Astrapi, which they don't.
Ah I see. I didn't see those specifications earlier. That actually mentions current output, not power output.
1.5 Vrms would translate to 140.62 mW of power into a 16-ohm load. However, it seems the Astrapi is current limited (140.62 mW would require 90 mA of current), so the actual power output at 16 ohms would be less.

The Astrapi delivers maximum current and maximum voltage into a 21.4-ohm load with 105 mW output.

The Astrapi delivers the minimum current and maximum voltage into a 150-ohm load with 15 mW output.


As I mentioned in the second post, the volume seems to be attenuated on the operating system level, which means anything less than 100% volume output would input a not-bit-perfect signal into the DAC section. This volume control is implemented similarly to the Objective DAC. Ideally the operating system volume level should be 100% if you want a better signal going into the amplifier section, yes, so it makes sense that 100% volume on the Astrapi would "activate" a line-out mode. It's more like a line-out plus pre-amp since it also has +_ gain.

 
Thanks for that. Would you mind showing what formulae you used to calculate the min-max output? 
 
So basically you saying that the volume control is a bit depth attenuator, very much like for the UD110. The reason that StonerAcoustics chose to go with a 32bit DAC and USB chip on the UD110 (UD100 was only 16/44.1) was because users where complaining that the volume control degraded the bit depth causing the noise floor to go up dramatically. 

 

[miceblue]

Thanks for that. Would you mind showing what formulae you used to calculate the min-max output? 

So basically you saying that the volume control is a bit depth attenuator, very much like for the UD110. The reason that StonerAcoustics chose to go with a 32bit DAC and USB chip on the UD110 (UD100 was only 16/44.1) was because users where complaining that the volume control degraded the bit depth causing the noise floor to go up dramatically. 

Yup, that's what the Audirvana Plus media player seems to suggest anyway. With a red volume dial, that would mean the DAC does internal digital volume management, which is what the OPPO HA-2 and LH Labs Geek Out use with the ESS Sabre 9018K2M DAC chip.



Ohm's Law
Voltage = Current x Resistance
V = I * R
I = V / R

Power = Voltage x Current
P = V * I
P = V^2 / R




10 mA or 0.010 A = min current
1.5 Vrms = max voltage

P = 1.5 Vrms * 0.010 mA = 0.015 W or 15 mW
P = V^2 / R
0.015 W = (1.5 Vrms)^2 / R
R = (1.5 Vrms)^2 / 0.015 W = 150 ohms




70 mA or 0.070 A = max current
1.5 Vrms = max voltage

P = 1.5 Vrms * 0.070 mA = 0.105 W or 105 mW
P = V^2 / R
0.105 W = (1.5 Vrms)^2 / R
R = (1.5 Vrms)^2 / 0.105 W = 21.428 ohms




With a 16-ohm load, maximum voltage output
P = V^2 / R
P = (1.5 Vrms)^2 / 16-ohms = 0.1406 W or 140.6 mW
P = V * I
0.1406 W = 1.5 Vrms * I
I = 1.5 Vrms / 0.1406 W = 0.09375 A or 93.75 mA

93.75 mA > 70 mA max

 

[DJScope]

Yup, that's what the Audirvana Plus media player seems to suggest anyway. With a red volume dial, that would mean the DAC does internal digital volume management, which is what the OPPO HA-2 and LH Labs Geek Out use with the ESS Sabre 9018K2M DAC chip.



Ohm's Law
Voltage = Current x Resistance
V = I * R
I = V / R

Power = Voltage x Current
P = V * I
P = V^2 / R




10 mA or 0.010 A = min current
1.5 Vrms = max voltage

P = 1.5 Vrms * 0.010 mA = 0.015 W or 15 mW
P = V^2 / R
0.015 W = (1.5 Vrms)^2 / R
R = (1.5 Vrms)^2 / 0.015 W = 150 ohms




70 mA or 0.070 A = max current
1.5 Vrms = max voltage

P = 1.5 Vrms * 0.070 mA = 0.105 W or 105 mW
P = V^2 / R
0.105 W = (1.5 Vrms)^2 / R
R = (1.5 Vrms)^2 / 0.105 W = 21.428 ohms




With a 16-ohm load, maximum voltage output
P = V^2 / R
P = (1.5 Vrms)^2 / 16-ohms = 0.1406 W or 140.6 mW
P = V * I
0.1406 W = 1.5 Vrms * I
I = 1.5 Vrms / 0.1406 W = 0.09375 A or 93.75 mA

93.75 mA > 70 mA max

 
Thanks for the explanation. So that's only 42.6mW into 64 Ohms (Havi B3 Pro 1). Does sound like its got way more power than that.

 

[RRod]

If it only downsampled to 44.1 kHz, that would imply that 192+ kHz sampling rate music files would work with the Astrapi, which they don't.
 

 
It has to be downsampling; how else is it playing up-to-192 on a 44.1-only DAC? It just seems like an odd "benefit" to do native downsampling when it's easy enough to just downsample your files to begin with, using whatever high-quality not-on-the-fly algorithm you want.

 

[miceblue]

It has to be downsampling; how else is it playing up-to-192 on a 44.1-only DAC? It just seems like an odd "benefit" to do native downsampling when it's easy enough to just downsample your files to begin with, using whatever high-quality not-on-the-fly algorithm you want.

Right, of course it's downsampling, but there could be something else to it other than solely downsampling; I'm guessing some proper filtering needs to be implemented somehow to reduce any aliasing problems that may occur.



[rule]
I'm trying out my 88 dB SPL/mW, 669-ohm AKG K240 Monitor headphones with the Astrapi right now. Volume 6/16 in OS X is about as loud as I would ever need for my quietest audio. Also, I think the Astrapi starts to run out of voltage swing at this point since the volume level doesn't really go up much further even at volume 16/16. I use the K240 Monitor as a voltage stress test for amps though, so for most headphones the Astrapi should be fine in terms of volume level.

 

[DJScope]

My Cozoy Astrapi mini review is up!

 
http://www.head-fi.org/products/cozoy-astrapi/reviews/12896
 

Spoiler: Warning: Spoiler!

Before I begin, I want to thank @H20Fidelity for providing me this review sample. I've had the Astrapi of just over a week and have not had a lot of time with it so this will be a mini review.
I did not purchase the Cozoy Astrapi but I will not let review bias effect me and will not hold any punches when there are punches to be throw. Now let's begin!
 
 
The Cozoy Astrapi is one of those devices that blows your mind away when you see it in real life. It is so comically small that you have to hold it in your hand before your mind can process how small it truly is. Looking at photos just does not shoot that message across at all. I know, because it happened to me. 
I wasn't expecting much when Luke first mentioned it to me. First thing I thought to myself was this is going to be one of those el'cheap-o DSP sound cards that get thrown around the market for $10. It looks that way, at least. And I hope that you can forgive me thinking that, because I never will. This was the grossest underestimation that I probably have ever made. Let me tell you why...
 

 

 

 

A little bit about the Fidue A71 

COZOY Astrapi APPLE MFi Approved Digital Lighting Amplifier for Android/iOS/PC

 

Spoiler: Description from PenonAudio Website

Description

1. COZOY is a digital-to-analog converter and amplifier that provide significantly improved headphone sound quality for audio players, tablets, and portable devices.
2. COZOY take the digital audio data stream from your preferred audio device and process and amplify it making your favorite headphones sound their best.
3. The Astrapi is all-aluminum build and modern design.
   
4. COZOY was designed for audio players, tablets and other portable devices running operating systems such as; Android, iOS and PC. 
5. COZOY incorporates proprietary digital Sound processing and conversion along with a high-performance headphone amplifier, all within an extremely portable form factor.
6. COZOY is designed for those who use their phones, tablets, laptops and other portable devices as their primary listening and viewing platforms and who seek the best-possible headphone or in ear listening experience for music, video, and gaming by providing improved resolution, spatiality, dynamics, and heightened realism.
7. COZOY is compatible with all audio formats supported by portable devices
8. COZOY’s extremely low power consumption allows for extended playing time and with its plug-and-play connectivity, eliminates any complex setups. 

Specification

1. Low power consumption with strong driving power
2. Clean Line-Out activated at Max Volume
3. Built-in DSP
4. Software DSD
5. External USB DAC Functionality (OSX + PC)
6. Compatible with various Android devices through OTG

1. Hi-resolution :24Bit-96khz 192khz
2. Headphone output :3.5mm
3. Impedance :16-100ohm at 1khz loading
4. Output vrms:1.5Vrms max
5. THD+N:0.003% ,1khz 0dbfs
6. SNR:105Db AT 3.3V power supply
7. Resolution :24bit/192khz sampling
8. System power current :10mA-70mA max
9. Power input:1.8V-3.3V+-10%
10. Output gain level step :3dB/step ;16 steps
11. Headphone power output :10mW max
12. Plug type: digital lightning connector
13. Cable length:20cm
14. Support USB2.0
15. Support connectors: Lightning connector .micro usb -micro usb ,micro usb-usb

Support Models

1. iPhone5,iPhone6/6s,iPad/iPod mini,iPod touch
2. Android (OTG Function)
3. PC/Laptop

Package

1. COZOY Astrapi DAC AMP
2. Android Cable
3. iOS Cable
4. PC Cable

 

1.  

Specifications

1. System power current :10mA - 70mA max.
2. Power input 1.8V-3.3V+-10%
3. Output gain level step: 3dB/step; 16 steps
4. Native 16/44.1 decoding and implementation of DSP tuning algorithms

* Output varies as power input may differ, this situation exists on every kind of OS
 
 

Packaging The Cozoy Astrapi comes in a very suspiciously Apple looking box. It's white with very subtle silver/grey writing. There is a print on every side of the box. It's not inviting or too busy. This is the kind of packaging I would've just walked past and not look twice. Some people look for different things, though.   On the bottom of the box there is a "General Guidelines" or basically all the instructions you'd ever need, including the specifications and packing list.    A very nice addition is the assembly drawing, or exploded diagram, however you prefer to call it. Shows you exactly what goes into making one of these units.   Inside the box is the Astrapi sitting nice and snug inside a felt covered foam block with a nice pull tab that is an awesome idea. The Astrapi is so small that you would have trouble taking it out with just your fingers. This idea was brilliant.    Underneath you get a Warranty card and you accessories are all located in the bottom compartment.		The box that I got looked a bit kicked around so don't blame Cozoy or me, blame Luke
​
Accessories   As for accessories, you get everything you need. Nothing more nothing less: 1x Apple Lightning to Micro USB cable 1x Micro USB to Micro USB cable 1x Micro USB to USB long cable		​
Design   The Cozoy Astrapi is a very nice looking unit. Beautifully lazer etched lines on the machined aluminium casing, that is pin stripe finished. Indents on both side for easy grip of the unit while plug and unplugging.  It is super elegant and practical. On the back is has a very nice, low profile shirt clip which feels tight and heavy duty. But those look kind of flimsy. I have use the shirt clip to pin the unit to the cable so it doesn't dangle around. It works well and holds on very strongly.
Compatibility   I had a few compatibility issue with this particular unit. With everything I tried.   Android Devices - Moto G XT1033 (5.0.2) & ASUS Nexus 7 2013 (5.0.2) Doesn't work as a plug and play device. To get it to work you must plug it in and restart the phone. After the phone reboots, the Astrapi is then used as the permanent sound device for you phone. You cannot make calls as the microphone does not work. But it does work for all your music and works quite well indeed. It is definitely an upgrade over the stock sound hardware in both these devices.   PC - Windows 8.1 & Window 7 This works perfectly as a plug and play device. Plug it in and off you go.  Only issue that there really is is that when the PC comes out of sleep or restarts the Astrapi is not recognised as a plugged in device. You must unplug it and plug it back in for it to be recognised again. A small quirk, but it's a minor issue.
Sound What I tried with the Astrapi: DUNU Titan 1 DUNU DN-1000 Havi B3 Pro 1 Takstar Pro 80 Goldring DR150   Because I've had so little time to get to know this little wonder I cannot go into a lot of detail on the sound. But my impressions are: The sound is smooth and transparent, maybe a little warm. Separation, sound stage and imaging is above par I would say. It paired very well with everything I threw at it, especially IEMs. I didn't hear any EMI coming from the PC ground or any low level hissing at all. Sound changes slightly depending on the source that is driving it. Higher current interfaces have better results. Eg. a 1A powered USB device/hub. It does fall short in power with full sized cans, but nothing major. When using things that have around 60 Ohms, the volume control does little from 50% - 100%. Volume wise it is loud enough, but it is not authoritative.
Comparison to the StonerAcoustic UD110 The UD110 is a very capable little device. But put up against the Astrapi as a DAC/amp on it's own, it go it's ***** handed to it. The Astrapi is not only a better looking and better built device. It (supposedly, haven't tried) works with Apple devices and Android devices. UD100 only works with Android and PC. The UD110 has something like 440 Ohms of output impedance, which is OK for a DAC coupled with a separate amplifier but as a standalone unit it's pretty bad.  The Astrapi sounds smooth and fuller than the UD110. The only thing that the UD110 has that the Astrapi doesn't is that it is about half the price and it plays a wide range of high resolution playback. Which quite useless when looking at the market it is targeting.
Conclusion   The Cozoy Astrapi is probably the most perfect looking portable DAC/amp I've ever seen. The small footprint and beautiful design makes it leagues better than the rest in practicality for easy to drive IEMs and headphones. Of course there are small quirks to work with, but that can possibly be ironed out with future updates.   Cheers!		​

 

[ZMan2k2]

Thinking of the Cozoy Astrapi for my S5, while listening at home.  I wouldn't take it out of the house, as I don't like bulk, and extra cables.  Anyways, would the Astrapi work for Stock Lollipop 5.0 and PowerAmp?

 

[7v4wfQZKvV]

   
It has to be downsampling; how else is it playing up-to-192 on a 44.1-only DAC? It just seems like an odd "benefit" to do native downsampling when it's easy enough to just downsample your files to begin with, using whatever high-quality not-on-the-fly algorithm you want.

 
They've talked about this on their Facebook page. They essentially say the sellers aren't giving the correct (or have outdated) information. It doesn't output at 192kHz / 24bit based on what they say.
https://www.facebook.com/permalink.php?story_fbid=1557914964459190&id=1531647370419283
 
On OS X, BitPerfect says it only supports 44.1kHz / 16bit, so it's downsampling the audio before it even sends it to the Astrapi.
 
I don't know a lot about audio, but isn't this the same as having a 720p TV that can accept a 1080p or 4k signal, but you still only end up seeing it at 720p because of the hardware?

 

[RRod]

   
They've talked about this on their Facebook page. They essentially say the sellers aren't giving the correct (or have outdated) information. It doesn't output at 192kHz / 24bit based on what they say.
https://www.facebook.com/permalink.php?story_fbid=1557914964459190&id=1531647370419283
 
On OS X, BitPerfect says it only supports 44.1kHz / 16bit, so it's downsampling the audio before it even sends it to the Astrapi.
 
I don't know a lot about audio, but isn't this the same as having a 720p TV that can accept a 1080p or 4k signal, but you still only end up seeing it at 720p because of the hardware?

 
Yeah that's what I was getting at. A device that only does 16/44.1 has to take anything higher and convert it, which is fine, but that should be made clear.

 

[DJScope]

  Thinking of the Cozoy Astrapi for my S5, while listening at home.  I wouldn't take it out of the house, as I don't like bulk, and extra cables.  Anyways, would the Astrapi work for Stock Lollipop 5.0 and PowerAmp?

 
Works on my stock Lollipop Moto G.

 

[ZMan2k2]

Works on my stock Lollipop Moto G.

Thanks. Might just be the next purchase, once finances clear up.

 

[Flomet]

Here is a review that I have just found.


http://theproaudiowebblog.com/cozoy-astrapi-review.html

 

[miceblue]

Here is a review that I have just found.

http://theproaudiowebblog.com/cozoy-astrapi-review.html

Nice. I didn't care for their use of overdone flowery terms for the sound quality, but I guess a slight U-shaped sound signature would summarise my sonic finding.

All in all the Astrapi provides a warming, rich, friendly, and fun (somewhat) U shaped frequency response that provides a deep very moderately slow full low end presence, a similarly moderately bold low-midrange texture, a relaxed sweeping mid-midrange, a transparent forward high-midrange, and a dreamy transparent and very smooth treble presence that doesn’t overly extend or ever reveal any sibilance issues.

Seriously....just what?


[rule]
In other news, I discovered this today, which probably confirms that the Astrapi doesn't work with legacy 30-pn devices.

 

[Flomet]

Nice. I didn't care for their use of overdone flowery terms for the sound quality, but I guess a slight U-shaped sound signature would summarise my sonic finding.
Seriously....just what?


[rule]
In other news, I discovered this today, which probably confirms that the Astrapi doesn't work with legacy 30-pn devices.

The reason I put this review up was that good or bad it is better to read all reviews before pulling the trigger.