This is a review and detailed measurements of the Emotiva BasX A7+ seven channel home theater amplifier. It was kindly drop shipped to me by a member and costs US $999.
I appreciated the compact size of the A7+. It is a class AB amplifier with linear power supply but doesn't weigh too much. Just heavy enough to give you a feeling of having bought something of substance. Despite its budget pricing, I was pleased to see balanced inputs:
Strangely though, both RCA and XLR are active at the same time. So don't connect both if you only need one.
We have both trigger input and output which is nice. There is also a useful switch to turn off the front panel light, a necessity in dark theaters especially since the default is bright blue LEDs.
There is a row of thick, traditional extruded aluminum heatsink which is a step above most AVRs. However, even half-way through testing, the channels under use were getting toasty. Seems like there are a couple of fans in there to keep things from going too crazy.
Protection circuit never came on despite pushing the amp well into clipping multiple times.
Emotiva BasX A7+ Amplifier Measurements
I focused my testing on Channels 1 and 2. I started with XLR input:
The gain is a hair higher than specified 29 dB. I like to see this reduced to 25 dB. As otherwise, it just costs you some SNR without much value. I was able to drive the amplifier to clipping with just 0.9 volt for 4 ohm and around 1.5 volt for 8 ohm. XLR sources are capable of producing higher voltages.
I also tested the above using RCA input. While SINAD was similar, the mains noise actually went down which is backward. I suspect there is a balanced to unbalanced converter.
As is, performance is below average of all amps tested:
But still in competent category.
We can see the cleaner RCA performance in our SNR tests:
Frequency response is non-load dependent due to it being class AB topology:
Unlike typical class AB though, intermodulation distortion is the same throughout the audible range:
Crosstalk was pretty poor:
I could see this in an AVR but not in an outboard amplifier like the A7+.
Power sweeps show that distortion sets in rather early:
Shared power supply and capable output stage allows the amp to far exceed its specs (125 watts) when driven with 2-channels:
This bodes well for when more channels are driven simultaneously.
40 Hz power as a result, is no problem for it either, with just a slight reduction:
Unlike typical class AB amp, we see a knee in distortion that lowers with frequency:
Strangely, after power up, performance continued to degrade a bit as the amp warmed up:
And sadly, there is likely going to be some audible pop on both power on and off:
Conclusions
Most of the measurements can be summed as, "not bad." I wish the company would strive to go a step higher to comply with the brand impression they like to have. A bit more focused on closed loop engineering using measurements could get them there.
Based on my subjective likeness of the A7+ packaging, I am going to go ahead and recommend the amplifier.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
I appreciated the compact size of the A7+. It is a class AB amplifier with linear power supply but doesn't weigh too much. Just heavy enough to give you a feeling of having bought something of substance. Despite its budget pricing, I was pleased to see balanced inputs:
Strangely though, both RCA and XLR are active at the same time. So don't connect both if you only need one.
We have both trigger input and output which is nice. There is also a useful switch to turn off the front panel light, a necessity in dark theaters especially since the default is bright blue LEDs.
There is a row of thick, traditional extruded aluminum heatsink which is a step above most AVRs. However, even half-way through testing, the channels under use were getting toasty. Seems like there are a couple of fans in there to keep things from going too crazy.
Protection circuit never came on despite pushing the amp well into clipping multiple times.
Emotiva BasX A7+ Amplifier Measurements
I focused my testing on Channels 1 and 2. I started with XLR input:
The gain is a hair higher than specified 29 dB. I like to see this reduced to 25 dB. As otherwise, it just costs you some SNR without much value. I was able to drive the amplifier to clipping with just 0.9 volt for 4 ohm and around 1.5 volt for 8 ohm. XLR sources are capable of producing higher voltages.
I also tested the above using RCA input. While SINAD was similar, the mains noise actually went down which is backward. I suspect there is a balanced to unbalanced converter.
As is, performance is below average of all amps tested:
But still in competent category.
We can see the cleaner RCA performance in our SNR tests:
Frequency response is non-load dependent due to it being class AB topology:
Unlike typical class AB though, intermodulation distortion is the same throughout the audible range:
Crosstalk was pretty poor:
I could see this in an AVR but not in an outboard amplifier like the A7+.
Power sweeps show that distortion sets in rather early:
Shared power supply and capable output stage allows the amp to far exceed its specs (125 watts) when driven with 2-channels:
This bodes well for when more channels are driven simultaneously.
40 Hz power as a result, is no problem for it either, with just a slight reduction:
Unlike typical class AB amp, we see a knee in distortion that lowers with frequency:
Strangely, after power up, performance continued to degrade a bit as the amp warmed up:
And sadly, there is likely going to be some audible pop on both power on and off:
Conclusions
Most of the measurements can be summed as, "not bad." I wish the company would strive to go a step higher to comply with the brand impression they like to have. A bit more focused on closed loop engineering using measurements could get them there.
Based on my subjective likeness of the A7+ packaging, I am going to go ahead and recommend the amplifier.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
