This is a review and detailed measurement of a very common power amplifier platform based on International Rectifier/Infineon's IRS2092 class D amplifier IC. The unit was kindly sent by a member to me for testing. Here is what it looks like:
The products seem to be based a reference design by International Rectifier although I can't find an exact match there. You can get everything from single amplifier board fully populated for USD $40 to the fully finished version I have including volume control for USD $298 from China. Just google for IRS2092 and IRAUD350 and you will get countless hits. Some come with volume control and others not.
Power specifications are all over the map. I think I saw one advertised to produce some 700 watts! Manufacturer specs are vague saying since the IC supports +- 100 volt, the can be used to create very high power amplifiers.
Due to use of linear power supply, the loaned amplifier is quite long and very heavy in front where the toroidal transformer is housed:
The unit is quite appealing to the audiophile. We have some fancy parts such as ELNA premium capacitors. Anyone want to guess as to whether they are real or not? Can't imagine they are at this price but the markings look good on them. At a glance, the construction seems nice and tidy. Closer inspection indicates otherwise.
For starters, when I opened the unit prior to start up I found one of the larger power supply capacitors was dangling by a thread! It had good bit of solder on its pins but likely due to oxidation on the capacitor pin, the solder was not holding. Since they did not glue down the caps as they show, the vibration in mail caused it to break free from its solder joint. I soldered the pin and did the same with a few other ones.
On safety front, there is of course no regulatory certification. I was pleased to see a safety ground wire to the chassis. They used a black color instead of proper green. Its gauge is too small likely to cause your home breaker to pop meaning if there is a short form hot to chassis, this wire may burn up leaving the case fully energized. Hopefully the smell of it will keep you away from touching it, maybe not. Then again I checked and they forgot to sand off the anodization from the chassis so this wire is not doing anything! The top lid likewise is insulated from the chassis due to the same finish acting as a barrier between the two. THE UNIT IS UNSAFE TO OPERATE AS BUILT!!!
There are other issues. See how a part of the insulation on the black wire is burned off. That doesn't do any damage here but shows sign of sloppy soldering. You can see it much better here:
I should note that the red wire is connected to the ground terminal on the PCB instead of black. Fortunately they seem to have also wired the inputs reversed so phase is maintained.
Very suspicious are these transistors which seem to have been hand soldered and in really poor way:
I think they are acting as regulators and are the hottest components as you see later. Likely they were damaged and they replaced and sold them as new.
Note that in some other variations of these designs the transistor is through-hole and mounted on the same heatsink as the output mosfet transistors.
It is one thing to buy a DAC without regulator certification but when it comes to power amplifications, you really have to be careful. Very high currents and voltages exist in these products and I highly suggest buying from reputable companies.
Anyway, let's get into measurements and see if better news awaits us there.
Measurements
Based on feedback from my last amplifier review, I decided to warm up the unit for an hour before taking measurements. Here is how it progressed during that time with respect to distortion:
One channel (in blue) keeps getting better with time but the other first shoots up in distortion and then back down. I tried to put the time to good use by opening the lid and taking some infrared shots but the moment I did, I got the spikes in distortion. I understand the lid encapsulating some of the noise but can't figure out why one channel got worse with the lid open but then then other got worse! Anyway, while the difference is not huge, allowing the unit to warm up improved its distortion metric by about 2 to 3 dB. Given the safety concerns I have, I am not sure you want to leave the unit on all the time but there is the data.
I then ran the dashboard at 5 watt of power and got this:
Yuck. Double yuck! Even at such low level of power we have pretty dirty output with 0.02% distortion. It is within the measurements of reference design though: https://www.infineon.com/dgdl/iraudamp7d.pdf?fileId=5546d462533600a40153569ad5ba2bf9
Power versus distortion give us this:
We have dual non-linearities. One sets in around 31 watts and the other, at 320 watts.
Reference design (at lower wattage) doesn't show anything as extreme as what I am measuring so something is not right in these instantiations:
Thermal stability was good though with the unit happily producing some 150 watts for 5 minutes:
Infrared camera shows the regulator transistors (?) to be the hottest component as I noted earlier:
We see that the power supply is running pretty cool which is nice. The capacitors are also way away from the heat sink which is nice as far as longevity.
The chassis is at room temperature which is sad because its mass could have been used to keep the amps much cooler. As it is, it is just a sturdy case to hold everything.
Back to measurements, I was not too happy to see such an early roll off in frequency response:
This likely indicates that there will be filter interactions with different speaker loads, causing their response to change within the audible band. Indeed even changing to 8 ohm load varies the response per reference design measurements:
Note the channel mismatch which was also visible in the dashboard. Fortunately this is not as big of a problem with speakers as it is with headphones but still, if you have a DSP, you may want to compensate for this there and use a volume control elsewhere in the chain.
Dynamic range is OK:
International Rectifier reference design runs at around 400 kHz (+- 25 kHz) and that is what we see:
I left the red channel without the AES-17 filter to show much noise this is producing and it is a lot. You will likely get interference on RF devices nearby.
Conclusions
Best way I can describe this amplifier is that it produces a lot of rather dirty power. If you want capacity at a bargain price, and you are not worried about the safety of the unit, this may fit the bill. But otherwise, I have to steer you all away from them. These are NOT high fidelity solutions when the manufacturer's own spec says THD+N is 0.01%. We have DACs that are 100 times better than this. Stop buying $4 cups of coffee, save your money, and buy something more decent.
-------------
As always, questions, comments, recommendations, etc. are welcome.
I am craving some prime rib. Please consider donating some money so that I can afford to get some using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
The products seem to be based a reference design by International Rectifier although I can't find an exact match there. You can get everything from single amplifier board fully populated for USD $40 to the fully finished version I have including volume control for USD $298 from China. Just google for IRS2092 and IRAUD350 and you will get countless hits. Some come with volume control and others not.
Power specifications are all over the map. I think I saw one advertised to produce some 700 watts! Manufacturer specs are vague saying since the IC supports +- 100 volt, the can be used to create very high power amplifiers.
Due to use of linear power supply, the loaned amplifier is quite long and very heavy in front where the toroidal transformer is housed:
The unit is quite appealing to the audiophile. We have some fancy parts such as ELNA premium capacitors. Anyone want to guess as to whether they are real or not? Can't imagine they are at this price but the markings look good on them. At a glance, the construction seems nice and tidy. Closer inspection indicates otherwise.
For starters, when I opened the unit prior to start up I found one of the larger power supply capacitors was dangling by a thread! It had good bit of solder on its pins but likely due to oxidation on the capacitor pin, the solder was not holding. Since they did not glue down the caps as they show, the vibration in mail caused it to break free from its solder joint. I soldered the pin and did the same with a few other ones.
On safety front, there is of course no regulatory certification. I was pleased to see a safety ground wire to the chassis. They used a black color instead of proper green. Its gauge is too small likely to cause your home breaker to pop meaning if there is a short form hot to chassis, this wire may burn up leaving the case fully energized. Hopefully the smell of it will keep you away from touching it, maybe not. Then again I checked and they forgot to sand off the anodization from the chassis so this wire is not doing anything! The top lid likewise is insulated from the chassis due to the same finish acting as a barrier between the two. THE UNIT IS UNSAFE TO OPERATE AS BUILT!!!
There are other issues. See how a part of the insulation on the black wire is burned off. That doesn't do any damage here but shows sign of sloppy soldering. You can see it much better here:
I should note that the red wire is connected to the ground terminal on the PCB instead of black. Fortunately they seem to have also wired the inputs reversed so phase is maintained.
Very suspicious are these transistors which seem to have been hand soldered and in really poor way:
I think they are acting as regulators and are the hottest components as you see later. Likely they were damaged and they replaced and sold them as new.
Note that in some other variations of these designs the transistor is through-hole and mounted on the same heatsink as the output mosfet transistors.
It is one thing to buy a DAC without regulator certification but when it comes to power amplifications, you really have to be careful. Very high currents and voltages exist in these products and I highly suggest buying from reputable companies.
Anyway, let's get into measurements and see if better news awaits us there.
Measurements
Based on feedback from my last amplifier review, I decided to warm up the unit for an hour before taking measurements. Here is how it progressed during that time with respect to distortion:
One channel (in blue) keeps getting better with time but the other first shoots up in distortion and then back down. I tried to put the time to good use by opening the lid and taking some infrared shots but the moment I did, I got the spikes in distortion. I understand the lid encapsulating some of the noise but can't figure out why one channel got worse with the lid open but then then other got worse! Anyway, while the difference is not huge, allowing the unit to warm up improved its distortion metric by about 2 to 3 dB. Given the safety concerns I have, I am not sure you want to leave the unit on all the time but there is the data.
I then ran the dashboard at 5 watt of power and got this:
Yuck. Double yuck! Even at such low level of power we have pretty dirty output with 0.02% distortion. It is within the measurements of reference design though: https://www.infineon.com/dgdl/iraudamp7d.pdf?fileId=5546d462533600a40153569ad5ba2bf9
Power versus distortion give us this:
We have dual non-linearities. One sets in around 31 watts and the other, at 320 watts.
Reference design (at lower wattage) doesn't show anything as extreme as what I am measuring so something is not right in these instantiations:
Thermal stability was good though with the unit happily producing some 150 watts for 5 minutes:
Infrared camera shows the regulator transistors (?) to be the hottest component as I noted earlier:
We see that the power supply is running pretty cool which is nice. The capacitors are also way away from the heat sink which is nice as far as longevity.
The chassis is at room temperature which is sad because its mass could have been used to keep the amps much cooler. As it is, it is just a sturdy case to hold everything.
Back to measurements, I was not too happy to see such an early roll off in frequency response:
This likely indicates that there will be filter interactions with different speaker loads, causing their response to change within the audible band. Indeed even changing to 8 ohm load varies the response per reference design measurements:
Note the channel mismatch which was also visible in the dashboard. Fortunately this is not as big of a problem with speakers as it is with headphones but still, if you have a DSP, you may want to compensate for this there and use a volume control elsewhere in the chain.
Dynamic range is OK:
International Rectifier reference design runs at around 400 kHz (+- 25 kHz) and that is what we see:
I left the red channel without the AES-17 filter to show much noise this is producing and it is a lot. You will likely get interference on RF devices nearby.
Conclusions
Best way I can describe this amplifier is that it produces a lot of rather dirty power. If you want capacity at a bargain price, and you are not worried about the safety of the unit, this may fit the bill. But otherwise, I have to steer you all away from them. These are NOT high fidelity solutions when the manufacturer's own spec says THD+N is 0.01%. We have DACs that are 100 times better than this. Stop buying $4 cups of coffee, save your money, and buy something more decent.
-------------
As always, questions, comments, recommendations, etc. are welcome.
I am craving some prime rib. Please consider donating some money so that I can afford to get some using:
Patreon: https://www.patreon.com/audiosciencereview), or
upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).