Cambridge Audio CXA81 Review (Sample 2)

[mike435]

If others are interested in seeing the MKII tested, I've offered to send one to Amir for a test run! Waiting to hear back from him. I would really like to see if CA has corrected some of the USB issues and the crosstalk between and digital and analog circuity.

 

[Urib]

This is a follow up to my first test of the Cambridge Audio CXA81. Results there showed fair bit of noise which was uncharacteristic of other products I have tested from the company. There were a lot of speculation as to the source of the problem but no data to back any. Fortunately company CEO was kind enough to contact me about a week later expressing surprised at my results. I asked them if they have measurements that are better. After some investigation, they said that they could replicate my results at their China manufacturing facility but not their R&D lab. I expressed that I no longer had the unit so there was not any work I could do to get to the bottom of this. I was offered a new unit and offer for payment to test again. I accepted the second unit but turn down the offer of payment.

In the communication, I was asked (as some members had also suggested) whether I lifted the USB ground using the switch in the back. I had not and ran those tests on the second unit. This is with the unit grounded:

View attachment 211293

The low frequency noise was much lower in this sample but you can still see the channel in red showing a wide spectrum of high frequency noise. This reduced its sinad fair bit compared to the "good" channel. Lifting the ground made that better but created a new problem:

View attachment 211294

At first it appears that there is more harmonic distortion given the spikes at 2, 3,4, 5, etc. KHz. But that is not so. USB micro packets are 1 Kbytes each and frame boundaries are showing up there as leakage from digital to analog circuits. So lifting the ground is really not a good solution here although I appreciate it being there as it may help some systems.

Post this we had a conference call with the designers of the product. Issue was brought up that this is an instrumentation thing that the Audio Precision analyzer is creating a loop and ground noise that would not be there. While this is true, I explained that I have tested hundreds of DACs that don't have this problem. I have once in a while seen this but it is exceptionally rare. Since overall results were more positive than the first sample, I offered to re-run all the measurements and post them.

A problem which we did NOT have a disagreement was, was the output limit of the pre-out. Like many AVRs, this is lower than I like to see at 1.5 volt. Above that it will saturate and distortion will increase.

With this intro, let's get into the measurements. Company has seen all the measurements and agrees with them.

CXA81 DAC Measurements (Sample 2)
I wanted to break the electrical link between the analyzer and CXA81 so started my DAC testing using Toslink optical. Here is our dashboard:

View attachment 211301

Note how I have picked the max output before output saturating. If we sweep the input level we see the full range of output relative to distortion:
View attachment 211303

As you see at 2 volts, we get down to SINAD of 75 dB which is what I measured with the first sample at that output.

I next switched to USB input:
View attachment 211304

We see noise intrusion reducing SINAD by a few dBs relative to TOSLINK optical. Here is a key discovery though: this is NOT due to USB input but mere connection of USB cable. You can see that noise even with Toslink when I have USB plugged in (but not used as an input):

View attachment 211305

Turns out this noise issue will proceed to corrupt the measurements of all other subsystems and was the reason why the amplifier for example did not perform well either in the first round. The impact with this second unit is lower than first sample though. This could be due to noise conditions changing on my test system (nature of computers and grounding) or something is different in the second sample.

To eliminate USB noise as a factor I continued the rest of DAC tests using Toslink so let's go through them quickly:

View attachment 211306

Linearity test was impacted by another rare issue which is power supply noise very close to the test tone of 200 Hz I use here. There is a strong bandpass filter here but not enough to get rid of that:
View attachment 211307

We see clear jitter sources but they are benign audibly:
View attachment 211309

IMD test shows more noise than I like to see but is very good at the limit, beating my reference DAC in blue:
View attachment 211310

Here is our reconstruction filter:
View attachment 211311

And THD+N vs frequency:
View attachment 211312

Pre-amp Measurements
Here again we see the impact of connecting the USB cable or not while testing analog in/analog out:

View attachment 211314

View attachment 211315

Power Amplifier Measurements
Let's start with our usual dashboard:

View attachment 211316

This is above average for all amplifiers tested to date and far better than noise-induced measurements of the first sample. Distortion is at -100 dB which is very good.
View attachment 211317
View attachment 211318

View attachment 211319

View attachment 211320

Power sweeps are much improved due to lower noise:
View attachment 211321

View attachment 211322

View attachment 211323

We see that in various frequencies as well:
View attachment 211324

The lower amount of noise allows distinction between the test tones.

Conclusions
The second sample combined with not connecting USB cable shows CXA81 in much better light. Performance is competent now for the class and transparent for most uses. Where would one put the blame for noise being induced using USB? Me? Instrumentation? Vagueness of computer audio/grounding? Some or all of the above?

When testing AVRs, I have started testing with Toslink to remove issues related to HDMI. I should have opted to do the same here but did not since I consider the unit in a different class. Still, I take some blame and should have done this before returning the unit. As I expressed to the company though, this is not a problem that other devices have so I implore them to investigate how to use this variability. After all, your system may be much worse than my configuration as your downstream devices and upstream computer may present even a worse situation. One likes to take comfort in thinking "one digital input is the same as another."

As it is, you have the tough situation that you can't leave USB cable connected lest you degrade the performance of the rest of the system. If you don't have an audible issue, this is not a concern but if it is, experiment with removing USB cable and see if fixes the problem.

For me personally, USB connection is critical and about the only input I would use on such a combo device. So the above is not something that works for me. But may be fine for you.

I also like to see output levels of 2 volts for unbalanced without saturating. We are seeing AVR/AVP companies going this way. No reason to do different in a combo device like this. Higher output level gives better freedom to use external amplifiers.

Finally, let me express my sincere and deep appreciate for Cambridge Audio and company CEO for accepting the challenging results of the first test and working with me on better clarity and a constructive path forward. In that regard, they earn highest levels of respect from me. I look forward to quality products from them that come across my bench.

They came out with a new cxa

This is a follow up to my first test of the Cambridge Audio CXA81. Results there showed fair bit of noise which was uncharacteristic of other products I have tested from the company. There were a lot of speculation as to the source of the problem but no data to back any. Fortunately company CEO was kind enough to contact me about a week later expressing surprised at my results. I asked them if they have measurements that are better. After some investigation, they said that they could replicate my results at their China manufacturing facility but not their R&D lab. I expressed that I no longer had the unit so there was not any work I could do to get to the bottom of this. I was offered a new unit and offer for payment to test again. I accepted the second unit but turn down the offer of payment.

In the communication, I was asked (as some members had also suggested) whether I lifted the USB ground using the switch in the back. I had not and ran those tests on the second unit. This is with the unit grounded:

View attachment 211293

The low frequency noise was much lower in this sample but you can still see the channel in red showing a wide spectrum of high frequency noise. This reduced its sinad fair bit compared to the "good" channel. Lifting the ground made that better but created a new problem:

View attachment 211294

At first it appears that there is more harmonic distortion given the spikes at 2, 3,4, 5, etc. KHz. But that is not so. USB micro packets are 1 Kbytes each and frame boundaries are showing up there as leakage from digital to analog circuits. So lifting the ground is really not a good solution here although I appreciate it being there as it may help some systems.

Post this we had a conference call with the designers of the product. Issue was brought up that this is an instrumentation thing that the Audio Precision analyzer is creating a loop and ground noise that would not be there. While this is true, I explained that I have tested hundreds of DACs that don't have this problem. I have once in a while seen this but it is exceptionally rare. Since overall results were more positive than the first sample, I offered to re-run all the measurements and post them.

A problem which we did NOT have a disagreement was, was the output limit of the pre-out. Like many AVRs, this is lower than I like to see at 1.5 volt. Above that it will saturate and distortion will increase.

With this intro, let's get into the measurements. Company has seen all the measurements and agrees with them.

CXA81 DAC Measurements (Sample 2)
I wanted to break the electrical link between the analyzer and CXA81 so started my DAC testing using Toslink optical. Here is our dashboard:

View attachment 211301

Note how I have picked the max output before output saturating. If we sweep the input level we see the full range of output relative to distortion:
View attachment 211303

As you see at 2 volts, we get down to SINAD of 75 dB which is what I measured with the first sample at that output.

I next switched to USB input:
View attachment 211304

We see noise intrusion reducing SINAD by a few dBs relative to TOSLINK optical. Here is a key discovery though: this is NOT due to USB input but mere connection of USB cable. You can see that noise even with Toslink when I have USB plugged in (but not used as an input):

View attachment 211305

Turns out this noise issue will proceed to corrupt the measurements of all other subsystems and was the reason why the amplifier for example did not perform well either in the first round. The impact with this second unit is lower than first sample though. This could be due to noise conditions changing on my test system (nature of computers and grounding) or something is different in the second sample.

To eliminate USB noise as a factor I continued the rest of DAC tests using Toslink so let's go through them quickly:

View attachment 211306

Linearity test was impacted by another rare issue which is power supply noise very close to the test tone of 200 Hz I use here. There is a strong bandpass filter here but not enough to get rid of that:
View attachment 211307

We see clear jitter sources but they are benign audibly:
View attachment 211309

IMD test shows more noise than I like to see but is very good at the limit, beating my reference DAC in blue:
View attachment 211310

Here is our reconstruction filter:
View attachment 211311

And THD+N vs frequency:
View attachment 211312

Pre-amp Measurements
Here again we see the impact of connecting the USB cable or not while testing analog in/analog out:

View attachment 211314

View attachment 211315

Power Amplifier Measurements
Let's start with our usual dashboard:

View attachment 211316

This is above average for all amplifiers tested to date and far better than noise-induced measurements of the first sample. Distortion is at -100 dB which is very good.
View attachment 211317
View attachment 211318

View attachment 211319

View attachment 211320

Power sweeps are much improved due to lower noise:
View attachment 211321

View attachment 211322

View attachment 211323

We see that in various frequencies as well:
View attachment 211324

The lower amount of noise allows distinction between the test tones.

Conclusions
The second sample combined with not connecting USB cable shows CXA81 in much better light. Performance is competent now for the class and transparent for most uses. Where would one put the blame for noise being induced using USB? Me? Instrumentation? Vagueness of computer audio/grounding? Some or all of the above?

When testing AVRs, I have started testing with Toslink to remove issues related to HDMI. I should have opted to do the same here but did not since I consider the unit in a different class. Still, I take some blame and should have done this before returning the unit. As I expressed to the company though, this is not a problem that other devices have so I implore them to investigate how to use this variability. After all, your system may be much worse than my configuration as your downstream devices and upstream computer may present even a worse situation. One likes to take comfort in thinking "one digital input is the same as another."

As it is, you have the tough situation that you can't leave USB cable connected lest you degrade the performance of the rest of the system. If you don't have an audible issue, this is not a concern but if it is, experiment with removing USB cable and see if fixes the problem.

For me personally, USB connection is critical and about the only input I would use on such a combo device. So the above is not something that works for me. But may be fine for you.

I also like to see output levels of 2 volts for unbalanced without saturating. We are seeing AVR/AVP companies going this way. No reason to do different in a combo device like this. Higher output level gives better freedom to use external amplifiers.

Finally, let me express my sincere and deep appreciate for Cambridge Audio and company CEO for accepting the challenging results of the first test and working with me on better clarity and a constructive path forward. In that regard, they earn highest levels of respect from me. I look forward to quality products from them that come across my bench.

They came out with a new CXA 81 MK2. Interesting to see if it performs better.

 

[Good Vibes]

Hi all

The CXA was my first Hifi purchase a few years ago and it has served me well. I recently bought a WiiM Ultra which I am very happy with and now I no longer require the multifunction of an integrated, I was thinking of selling the 81 and “upgrading” to a power amp. If I were to do so, would there be a noticeable difference in sound quality? My speakers have 90db sensitivity so extra power isn’t necessary.

 

[Evo42]

Hi all

The CXA was my first Hifi purchase a few years ago and it has served me well. I recently bought a WiiM Ultra which I am very happy with and now I no longer require the multifunction of an integrated, I was thinking of selling the 81 and “upgrading” to a power amp. If I were to do so, would there be a noticeable difference in sound quality? My speakers have 90db sensitivity so extra power isn’t necessary.

I am in a very similar position but with a cxa80 and thinking of adding a wiim ultra and just getting a power amp, with purifi class d amp being the preference. Through spending time here and generally researching hifi it is apparent that the audible impact and difference of amplification is massively overplayed. That being said you may be able get an excellent class d power amp for the price you get for selling your cxa81.

Do you have a good subwoofer because if not that would be my next upgrade. Also the beauty of the wiim ultra is that you can run a high pass filter to your speakers so the amp is not sending the low frequencies to your speakers which will mean the amp can drive your speakers more efficiently as it's not trying to use so much power digging to those low frequencies.

 

[Good Vibes]

I am in a very similar position but with a cxa80 and thinking of adding a wiim ultra and just getting a power amp, with purifi class d amp being the preference. Through spending time here and generally researching hifi it is apparent that the audible impact and difference of amplification is massively overplayed. That being said you may be able get an excellent class d power amp for the price you get for selling your cxa81.

Do you have a good subwoofer because if not that would be my next upgrade. Also the beauty of the wiim ultra is that you can run a high pass filter to your speakers so the amp is not sending the low frequencies to your speakers which will mean the amp can drive your speakers more efficiently as it's not trying to use so much power digging to those low frequencies.

I can highly recommend the Ultra, it isn’t perfect but is very good for the money. I am already looking forward to the next version of the Ultra to see what improvements can be made. Yes, I have a subwoofer and the bass management features on the Ultra has helped me to better integrate the sub.

I have been considering changing amp for some time but like you, have been led to believe that it won’t have much or any impact on the sound. If that is truly the case, I’d rather invest the money elsewhere.

May I ask, is your name inspired by the Evo 4.2 speakers?

 

[Evo42]

I can highly recommend the Ultra, it isn’t perfect but is very good for the money. I am already looking forward to the next version of the Ultra to see what improvements can be made.

Yes I am holding out just to see what's next but reckon I will grab this one or the update.

Yes, I have a subwoofer and the bass management features on the Ultra has helped me to better integrate the sub.

All over it already. This is one of the big reason I want the ultra plus the EQ.

May I ask, is your name inspired by the Evo 4.2 speakers?

Yeah spot on. Great speakers for the price and love their natural sounding clarity and mid-range but in hindsight I should have got speakers with better vertical off axis performance as they're in a open plan area where we listen at different points. But they were a 40th present to myself with the Cambridge amp and svs sb2000pro so I will never get rid of them. I will just move them to another room with a fixed listening position later on and get the predictable awesome choice of some kef Metas hahaha

 

[drodgers]

I switched from a CXA81 to a pair of Fosi Mono V3s (to make integration with my AVR/home theatre setup easier) and there was no audible difference.

 

[Good Vibes]

I had and sold the Evo 4.2’s and I have been struggling to forget them ever since. The way that mid dome replicates vocals, instruments, synths… incredible. That AMT… fantastic! The bass… not the most well defined or fast sounding but still very pleasing and the way it filled my room was soooo good. For about 35% of my collection they really sounded phenomenal but for a large section of my music their presentation made me want to change song and I found myself not listening to a lot of my favourites. When I sold them I instantly regretted it and very nearly bought them again. One regret I have is not trying them with a more powerful amplifier to see if it might have improved the bass performance. I replaced them with LS50’s (phenomenal imaging), R3’s (didn’t like) and eventually Heco Celan Rev 3’s. I still crave the effects 4.2’s gave me on certain songs. They really spoiled me.

I was hovering over the buy it now button for a while on the Ultra but got it on sale and I quickly pressed the button. Absolute bargain.

 

[Snoopy]

I had and sold the Evo 4.2’s and I have been struggling to forget them ever since. The way that mid dome replicates vocals, instruments, synths… incredible. That AMT… fantastic! The bass… not the most well defined or fast sounding but still very pleasing and the way it filled my room was soooo good. For about 35% of my collection they really sounded phenomenal but for a large section of my music their presentation made me want to change song and I found myself not listening to a lot of my favourites. When I sold them I instantly regretted it and very nearly bought them again. One regret I have is not trying them with a more powerful amplifier to see if it might have improved the bass performance. I replaced them with LS50’s (phenomenal imaging), R3’s (didn’t like) and eventually Heco Celan Rev 3’s. I still crave the effects 4.2’s gave me on certain songs. They really spoiled me.

I was hovering over the buy it now button for a while on the Ultra but got it on sale and I quickly pressed the button. Absolute bargain.

I upgraded from the Evo 4.2 + Rel Tzero MK3 subwoofer to the Wharfedale Super Linton (no subwoofer).

Running both setup with the CXA81 (v1) with the CXN v2 (or SMSL D300 sometimes).

The CXA81 is really good with both setups. I don’t see myself going to some class D only for better performance numbers that hardly make a difference in the real world.
Especially not a Fosi amp.

I’m keeping the Evo 4.2 for a desktop/bedroom setup and also the CXA81 if I ever upgrade. Especially the Evo 4.2 with EQ are way to good for the money

 

[Good Vibes]

I upgraded from the Evo 4.2 + Rel Tzero MK3 subwoofer to the Wharfedale Super Linton (no subwoofer).

Running both setup with the CXA81 (v1) with the CXN v2 (or SMSL D300 sometimes).

The CXA81 is really good with both setups. I don’t see myself going to some class D only for better performance numbers that hardly make a difference in the real world.
Especially not a Fosi amp.

I’m keeping the Evo 4.2 for a desktop/bedroom setup and also the CXA81 if I ever upgrade. Especially the Evo 4.2 with EQ are way to good for the money

Yes I agree, I don’t want to change amp if there will be no audible improvement to the sound regardless of better measurements. I had a slight out of warranty issue with my CXA 81 and CA were very responsive and helpful so I have a good opinion of them as a company. I frequently read about issues people have with their fantastic measuring equipment and the poor customer service from the manufacturers.

Wow man, you must have a big desk to put those 4.2’s on lol I can fully relate to not wanting to selling them, I wish I had kept mine. Mine were an early edition made with real wood veneer… breaks my heart.

 

[Snoopy]

.

Wow man, you must have a big desk to put those 4.2’s on lol I can fully relate to not wanting to selling them, I wish I had kept mine. Mine were an early edition made with real wood veneer… breaks my heart.

I got mine pretty early as well. I think April 2021. I got B&W stav24 stands for them filled quartz sand to make the stands heavier. Should make for a nice desktop setup for console gaming and some Netflix with a 32“ OLED monitor.

Also I paid only 640 or 680€ for the Evo4.2.. if I where to sell them now I would maybe get 300-400€ on the used market . Not worth it and ultimately paying more for a replacement desktop speaker.

Same for the CXA81 and CXN v2.. I got both open box for under 900€ each …Cambridge is still updating the CXN v2 and their StreamMagic app.

Loosing money on both to replace it with a Fosi and Wiim ? Dear god no.
That stuff is landfill in a couple of years. The Cambridge stuff will probably still work and have value in 20 years.

(If I’m going to upgrade my main setup it’s going to be a Yamaha A-S2200 for its built quality, parts used and the timeless design )

 

[Timmeon]

Hey @Good Vibes and @Evo42, was up against a similar question not long ago, I switched from a CXA80 (first gen) to Benchmark & Bryston separates. No audible improvement at my listening level anyway. I would suggest prioritizing the user experience, consider your main touchpoints (the apps you interface with frequently). Switching from Volumio to Roon was a much more significant and positive change in my everyday experience. The Wiim might be a great option from what I hear about how they listen to user feedback and incorporate it into development. That said, it is kind of nice knowing you have a s#!t ton of power available if you need it. Enjoy!

 

[Good Vibes]

Hey @Good Vibes and @Evo42, was up against a similar question not long ago, I switched from a CXA80 (first gen) to Benchmark & Bryston separates. No audible improvement at my listening level anyway. I would suggest prioritizing the user experience, consider your main touchpoints (the apps you interface with frequently). Switching from Volumio to Roon was a much more significant and positive change in my everyday experience. The Wiim might be a great option from what I hear about how they listen to user feedback and incorporate it into development. That said, it is kind of nice knowing you have a s#!t ton of power available if you need it. Enjoy!

Great feedback, thank you!

The CXA 81 took a bit of a bashing on here which had me thinking I will get better sound quality from a better measuring amplifier. It appears that any inadequacies it may be deemed to have, are inaudible to the human ear and that it is a very competent amplifier.

 

[Timmeon]

Great feedback, thank you!

The CXA 81 took a bit of a bashing on here which had me thinking I will get better sound quality from a better measuring amplifier. It appears that any inadequacies it may be deemed to have, are inaudible to the human ear and that it is a very competent amplifier.

I agree, far from state-of-the-art but good enough for human consumption. It's a nice-looking unit and includes plenty of connectivity, even if the binding posts appear to be sourced from Lego.

 

[Snoopy]

Great feedback, thank you!

The CXA 81 took a bit of a bashing on here which had me thinking I will get better sound quality from a better measuring amplifier. It appears that any inadequacies it may be deemed to have, are inaudible to the human ear and that it is a very competent amplifier.

Well the amp section seems to be fine.

„This is above average for all amplifiers tested to date and far better than noise-induced measurements of the first sample. Distortion is at -100 dB which is very good“

The main issue seems to be with the USB input where performance is not up to topping style 120db SINAD..
(Do you really need that ? Can you hear it? ).

But the CXA81 got XLR inputs , so feel free to use another DAC streamer with your unit.

 

[Good Vibes]

even if the binding posts appear to be sourced from Lego.

Very good point, they are terrible!

 

[Snoopy]

I put my CXN v2 back into the Living room setup with the CXA81.. (XLR connection). Couldn’t hear a difference to the SMSL D300 , even when I tried upsampling 768khz pcm or DSD512 in roon.

The CXN v2 upsamples everything to 384khz anyway and I let roon upsample everything before that to 192khz with Headphone EQ applied or room EQ (housecurve for iOS).

(And I got to take a bunch more cables and a raspberry pi out of the rack)

 

[drodgers]

I don’t see myself going to some class D only for better performance numbers that hardly make a difference in the real world.
Especially not a Fosi amp.

Unnecessary shade on Fosi! I ended up with 7 channels of amplification at 2x the power per channel for less than the price of the CXA81 (which I got at about 50% off to begin with). All of the channels turn on automatically when needed and if I ever have any reliability problems, I can switch out just the faulty channel with a same-day replacement from Amazon for a pittance.

I was definitely an upgrade in my case (where I wanted a separate pre-amp).

I still use the CXA81 in another system and it's great, but it's definitely a much worse value proposition than the Fosis.

 

[Snoopy]

Unnecessary shade on Fosi! I ended up with 7 channels of amplification at 2x the power per channel for less than the price of the CXA81 (which I got at about 50% off to begin with). All of the channels turn on automatically when needed and if I ever have any reliability problems, I can switch out just the faulty channel with a same-day replacement from Amazon for a pittance.

I was definitely an upgrade in my case (where I wanted a separate pre-amp).

I still use the CXA81 in another system and it's great, but it's definitely a much worse value proposition than the Fosis.

some people like to stick to brands associated with audio gear or instruments, music Production etc

Just take Denon , Sony for example with DSD, PCM, CD all these things we discusse in this forum.
Or who doesn’t think about a Grand Piano when you see Yamaha gear .

Just trying to say that I rather buy something from a established brand that might have invented something, works with artists that I like or has a significant place in this hobby.

And even if I could get 50 channels of Fosi applications I would rather have something else in my home

It’s for the same reason I prefer to buy a LG or Sony TV over hinsense or TLC

 

[Evo42]

Especially the Evo 4.2 with EQ are way to good for the money

Yeah I am thinking once I get a wiim ultra or its successor I'll run two EQ settings for different listening heights(standing and sitting) to deal with that tweeter set up