Articles, Reviews and Measurements of Audio Products
HSU HB-1 MK2 Review (Horn Speaker)
This is a review and detailed measurements of the HSU HB-1 MK 2 bookshelf speaker. It is on kind loan from a member and costs US $169 each as of this writing (normal price $199).
I can't say I am a fan of the industrial looking horn but otherwise, the HB-1 looks fine:
As you see, it uses a horn-loaded tweeter. Not much to see on the back:
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more...
I can't say I am a fan of the industrial looking horn but otherwise, the HB-1 looks fine:
As you see, it uses a horn-loaded tweeter. Not much to see on the back:
Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise. Both of these factors enable testing in ordinary rooms yet results that can be more...
Shenzhenaudio Topping EX5 Review (DAC and Headphone Amplifier)
This is a review and detailed measurements of the Topping EX5 produced exclusively for Shenzhenaudio. The EX5 is slated to cost US $349.99 which it is released. The sample I have is from production run but is awaiting the manual for formal shipments. It was sent to me by Shenzhenaudio.
The EX5 goes into one of my favorite "skins" from Topping with the cute orange LED display:
As you can see, this is a combination DAC and headphone amplifier. Note that the XLR style headphone out is for convenience and does not produce more power.
There are however and surprisingly so, balanced XLR outputs:
We also have the now standard Bluetooth input.
The remote control cycles through four output modes which selectively turns on the different outputs for both on. I did not have the patience to decode all four modes.
But I imagine this is very useful to control different output...
The EX5 goes into one of my favorite "skins" from Topping with the cute orange LED display:
As you can see, this is a combination DAC and headphone amplifier. Note that the XLR style headphone out is for convenience and does not produce more power.
There are however and surprisingly so, balanced XLR outputs:
We also have the now standard Bluetooth input.
The remote control cycles through four output modes which selectively turns on the different outputs for both on. I did not have the patience to decode all four modes.
But I imagine this is very useful to control different output...Edifier S2000 Pro Review (Powered Monitor)
This is a review and detailed measurements of the Edifier S2000 Pro monitor (powered speaker). It was kindly sent to me by a member and costs US $400 on Amazon including Prime shipping.
The S2000 looks better than its cost indicates:
Connectivity is a lot richer than professional monitors anywhere close to this price range including a remote control:
I only had this master unit for testing. I like the large controls in the back though the rotary control for volume has no indication. So you are adjusting it blind. There is also no detent to indicate neutrality on the bass and treble controls. I tested the unit as you see. Pressing the volume control in selects the input and a small display on the front indicates which input is chosen.
Measurements that you are about to see were performed using the Klippel Near-field Scanner...
The S2000 looks better than its cost indicates:
Connectivity is a lot richer than professional monitors anywhere close to this price range including a remote control:
I only had this master unit for testing. I like the large controls in the back though the rotary control for volume has no indication. So you are adjusting it blind. There is also no detent to indicate neutrality on the bass and treble controls. I tested the unit as you see. Pressing the volume control in selects the input and a small display on the front indicates which input is chosen.
Measurements that you are about to see were performed using the Klippel Near-field Scanner...
Topping D90SE Review (Balanced DAC)
This is a review and detailed measurements of the Topping D90SE flagship balanced USB DAC. It was sent to me by the company for testing and I believe costs US $899.
The D90SE comes in the same clothes as current class of Topping products which is just fine with me:
We have the usual inputs and outputs including Bluetooth:
The architecture here is based on ESS ES9038PRO DAC instead of AKM silicon. Hopefully this means better availability of parts and DACs.
Topping D90SE DAC Measurements
Out of box output voltage is our standard 4 volts but there is also a setting to adjust that to 5 volt (see test of that later). Let's start with USB input and balanced XLR output:
Oh wow! We have a record breaker here when it comes to SINAD:
The Audio Precision analyzer puts severe strain on getting such high numbers due to its own...
The D90SE comes in the same clothes as current class of Topping products which is just fine with me:
We have the usual inputs and outputs including Bluetooth:
The architecture here is based on ESS ES9038PRO DAC instead of AKM silicon. Hopefully this means better availability of parts and DACs.
Topping D90SE DAC Measurements
Out of box output voltage is our standard 4 volts but there is also a setting to adjust that to 5 volt (see test of that later). Let's start with USB input and balanced XLR output:
Oh wow! We have a record breaker here when it comes to SINAD:
The Audio Precision analyzer puts severe strain on getting such high numbers due to its own...
GaN Systems Amplifier Eval Board Measurements
This is on overview of new type of transistor called GaN (Gallium Nitride) and an evaluation package from GaN system which kindly sent it to me last year(!). I lost touch with them for a while and hence the lateness of this write up.
This is a shot of the eval board (GS-EVB-AUD-xxx1-GS) which is rated at 200 watts/channel into 8 ohm:
Notice the absence of any heatsinks. Here is the accompanied 400 watt switching power supply:
GaN transistors are to the left of the transformer on the bottom with yellow stickers on them. Again, no heatsink due to high efficiency.
Current switching power supplies and amplifiers (Class D) use a type of transistor called MOSFET. These transistors are used in digital systems and are designed to be operated at their extreme operation point (fully conducting or not). This provides high efficiency because the transistor is not kept in less conductive state that generates a lot of losses...
This is a shot of the eval board (GS-EVB-AUD-xxx1-GS) which is rated at 200 watts/channel into 8 ohm:
Notice the absence of any heatsinks. Here is the accompanied 400 watt switching power supply:
GaN transistors are to the left of the transformer on the bottom with yellow stickers on them. Again, no heatsink due to high efficiency.
Current switching power supplies and amplifiers (Class D) use a type of transistor called MOSFET. These transistors are used in digital systems and are designed to be operated at their extreme operation point (fully conducting or not). This provides high efficiency because the transistor is not kept in less conductive state that generates a lot of losses...
ZMF Atticus Review (Headphone)
This is a review and detailed measurements of the ZMF Atticus headphone. It is on kind loan from a member and costs US $1,099.
Member sent me three pairs of pad for them but they all look the same and neither he, nor I know if these are stock ones or not. Looking at the pictures online, they look similar to the OEM ones.
As a woodworker, I very much admire the figured wood used for the cups:
This looks like zebra wood to me. Company references different wood species in different pages so not sure exactly what it is. Note that fair amount of sound escapes the vents so don't assume these are "closed headphones" in the classical sense.
Headphones this big are naturally on the heavy side with the Atticus clocking at 500 grams:
The large cups are very comfortable though and so I did not find them tiring in the few hours I wore them. Cup inside dimensions are 75x54x25 mm (height, width, depth).
Note: The measurements...
Member sent me three pairs of pad for them but they all look the same and neither he, nor I know if these are stock ones or not. Looking at the pictures online, they look similar to the OEM ones.
As a woodworker, I very much admire the figured wood used for the cups:
This looks like zebra wood to me. Company references different wood species in different pages so not sure exactly what it is. Note that fair amount of sound escapes the vents so don't assume these are "closed headphones" in the classical sense.
Headphones this big are naturally on the heavy side with the Atticus clocking at 500 grams:
The large cups are very comfortable though and so I did not find them tiring in the few hours I wore them. Cup inside dimensions are 75x54x25 mm (height, width, depth).
Note: The measurements...
AKG K240 55 Ohm Review (Headphone)
This is a review and detailed measurements of the AKG K240 55 ohm Semi-Open, "Professional Studio" Headphones. It is on kind loan from a member and costs US $69 from Amazon including Prime shipping.
Note: our company, Madrona Digital carries Harman products. AKG is owned by Harman so feel free to read as much bias as you feel necessary into this review.
The K240 has a kind of retro "aviator" look to it:
The sample I have has thicker velour pads as you see. Owner was kind enough to also supply the original, thin pads but they were severely degraded so I did not use them. There were also a couple of filters included. I am not sure if they were part of the original design and not used when the pads were swapped or what. No, I am not going to measure this headphone twice. Not everything needs to be a science a project.
These are very light headphones owing to thin plastics used:
During playback I could...
Note: our company, Madrona Digital carries Harman products. AKG is owned by Harman so feel free to read as much bias as you feel necessary into this review.
The K240 has a kind of retro "aviator" look to it:
The sample I have has thicker velour pads as you see. Owner was kind enough to also supply the original, thin pads but they were severely degraded so I did not use them. There were also a couple of filters included. I am not sure if they were part of the original design and not used when the pads were swapped or what. No, I am not going to measure this headphone twice. Not everything needs to be a science a project.
These are very light headphones owing to thin plastics used:
During playback I could...
Polk Monitor 40 Series II Review (Speaker)
This is a review and detailed measurements of the Polk Monitor 40 Series II bookshelf "MTM" speaker. It is on kind loan from a member and costs US $200 on Amazon for a pair including Prime shipping.
The Monitor 40 looks pretty decent for such a budget speaker:
After decades of surviving in brutal consumer market for speakers, Polk knows what it is doing here. And that involves super lightweight design and shoddy construction that allowed the front baffle completely separate itself from the enclosure in shipping!
They have a rabbet all around which provides for large surface area for the glue and air tight construction. Why did they resort to these wedges that gave out due to weak fibers in the MDF? A couple of screws would have helped keep it there as well.
At least there is some foam inside:
They put money toward bi-wiring terminals that no one uses but likely checks a box for...
The Monitor 40 looks pretty decent for such a budget speaker:
After decades of surviving in brutal consumer market for speakers, Polk knows what it is doing here. And that involves super lightweight design and shoddy construction that allowed the front baffle completely separate itself from the enclosure in shipping!
They have a rabbet all around which provides for large surface area for the glue and air tight construction. Why did they resort to these wedges that gave out due to weak fibers in the MDF? A couple of screws would have helped keep it there as well.
At least there is some foam inside:
They put money toward bi-wiring terminals that no one uses but likely checks a box for...
Jensen ISO-Max CI-1RR Review (Isolation Transformer)
This is a review and detailed measurements of the Jensen ISO-MAX CI-1RR isolation transformer usually used to remove ground loops. It was kindly bought and drop shipped to me by the member and costs US $130.
This is a mono device and could not be simpler with just an input and output:
No power is needed.
Basically device takes the typical safety ground referenced RCA signal and delivers a floating signal independent of said ground.
Jensen ISO-MAX CI-1RR Measurements
Our focus in the measurements are to see if there is an loss of fidelity by inserting this device in the audio chain. Let's start with our usual dashboard of 1 KHz tone:
In a twist of faith, the addition of ISO-MAX created mains hum where none existed before! The amount of mains noise induced was location dependent which tells me it is picking it up from its environment. I am not clear on the exact mechanism for this pick up.
Anyway, the main...
This is a mono device and could not be simpler with just an input and output:
No power is needed.
Basically device takes the typical safety ground referenced RCA signal and delivers a floating signal independent of said ground.
Jensen ISO-MAX CI-1RR Measurements
Our focus in the measurements are to see if there is an loss of fidelity by inserting this device in the audio chain. Let's start with our usual dashboard of 1 KHz tone:
In a twist of faith, the addition of ISO-MAX created mains hum where none existed before! The amount of mains noise induced was location dependent which tells me it is picking it up from its environment. I am not clear on the exact mechanism for this pick up.
Anyway, the main...
Audio Technica ATH-ADX5000 Review (Headphone)
This is a review and detailed measurements of the Audio Technica flagship headphone, the ATH-ADX5000. It is on kind loan from a member and costs US $1,999.
After testing a lot of heavy headphones, the ATH-ADX5000 feels like it is light as feather:
The lightness is great as far as wear comfort but does not impart feeling of luxury. The unit only weighs 275 grams despite sporting large cups:
The inside cup dimensions are 60x60x20 mm (height x width x depth).
The owner supplied them with an aftermarket cable that was light and nice to use with it. The stock cable is super stiff from what I have seen online.
Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements...
After testing a lot of heavy headphones, the ATH-ADX5000 feels like it is light as feather:
The lightness is great as far as wear comfort but does not impart feeling of luxury. The unit only weighs 275 grams despite sporting large cups:
The inside cup dimensions are 60x60x20 mm (height x width x depth).
The owner supplied them with an aftermarket cable that was light and nice to use with it. The stock cable is super stiff from what I have seen online.
Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements...