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Cambridge Audio CXA81 Review (Sample 2)

Another CONCLUSION:
I am glad I went PA5. Terrific.
:):):):)
 
Had the CXA60 before, my country was on 240V 50Hz AC supply.

I couldn't help but wondering why my satellite TV audio connecting using coaxial to the CXA60 DAC will be experiencing intermittent audio drops (every few seconds) when somebody was using instant water heater for bath, it was totally unusable. Analog or optical inputs weren't affected. The other modern amps I had (Onkyo, NAD C368, Marantz) has no such issue.

It was purchased as used unit so without warranty, sold it as I could do nothing and that bug was affecting my TV watching...
 
So we now know why the device performs badly, but it still does perform badly in relevant everyday usage scenarios. I think it's okay to show the performance at 1.5 V over RCA, but a fair comparison with every other device tested would be at 2 V, where the CXA81 plain sucks and doesn't even remotely reach CD audio level performance.

It sounds like Cambridge Audio designers did not know about the USB noise problem, but it still exists. Fair enough. But they absolutely knew that the distortion on the RCA out becomes inacceptable above 1.5 V and still permitted the user to run the device like that. They could just have limited the RCA out to 1.6 V or so and everybody would have been happy. If you needed more voltage, they could even have sold you a seperate pre-amp: More money for them, more performance for the user/buyer. That's just poor design and - in my book - inacceptable for a device at this price point. Very disappointing.
 
Nice to see such a thorough response by everyone involved.
 
amirm said:
It would be the best invention in the world. I use my tiller to attack them but they come right back up when you plantings are in there.
Click to expand...
That’s where you’re going wrong. You need to get yourself a Dutch hoe (if you need to google it, careful with the spelling).

Turning the soil over with a tiller just brings more weed seeds up to the surface.
 
hmmm... Good for the collaboration from CA's side. I went through the comments from the previous review and I am not sure how much confidence I have in other decapitated reviews where the maker(s) didn't even bother to challenge. For example there are no measurements with optical for the chord mojo 2 and/or intermodulation distortion. I guess it is all work in progress here like in every measuring methodology.
 
RandomEar said:
It sounds like Cambridge Audio designers did not know about the USB noise problem, but it still exists. Fair enough. But they absolutely knew that the distortion on the RCA out becomes inacceptable above 1.5 V and still permitted the user to run the device like that. They could just have limited the RCA out to 1.6 V or so and everybody would have been happy.
Click to expand...

It's very common for consumer audio (pre/integrated/power) amps to have a volume control that allows you to overdrive any of the outputs (speaker/line/pre out). The reason being they provide ample gain to support low level input signals, especially with devices with analog inputs. In consumer audio signal levels are not always standardized (or standards not respected) to the same extend as in pro audio, and signal levels cannot be monitored as well (peak meters that can monitor all in and outputs).

According to the CXA81 specifications Cambridge follows the traditional -10 dBV standard, being 0,3 V rms, for the line inputs. The problem is, in consumer audio there's no standard for preamp ouputs, or the inputs of devices you typically connect to them like a power amplifier. If you look at the spec's of the Azure 851W power amp you see Cambridge uses a sensitivity of 1,5 V rms, the limit of the CXA81 preamp outputs. So within the brand the levels are consistent.

Want to connect another amplifier to the CXA81, say a popular NAD C298? Input sensitivity 1,43V rms so no problem. Maybe a Krell Duo 300 XD? Oops ... , an input sensitivity of 2,4 V rms. Let's look at Asia; a Technics SE-R1 power amp, input sensitivity 1,2V. Between the Krell and the Technics there's a difference of almost 8dB, and we expect this all to work together flawlessly (or without consideration)?

And it can get worse. Some brands don't even specify the input sensitivity. Want to connect a REL or SVS subwoofer? Good luck, ... no input sensitivity to be found.

So this whole gain structure thing is a general problem in consumer audio.

Note: when it comes to the digital inputs we see that even when the preamp output is limited to 1,5V the CXA81 provides 18 dB dynamic range (108dB), which is perfectly fine. It confirms the 1,5 V preamp out level is a design choice and not a screw up. We've seen other examples over here.
 
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Another Audiophile said:
"Still, I take some blame and should have done this before returning the unit."

An apology will be more appropriate @amirm
Click to expand...

An apology for an issue that never happened with the numerous other devices Amir already tested, and that can happen to anyone who uses the device in practice?
 
You are both kinda right.
If someone buys this thing with the intention to use the USB port it's going to be a disappointment probably.

If someone uses it with a external DAC , streamer etc it's going to be fine.

But in that (my) case a Poweramp would do as well.
 
Snoopy said:
If someone buys this thing with the intention to use the USB port it's going to be a disappointment probably.
Click to expand...

I don’t hear any difference in noise from mine with or without a USB cable plugged in. What should I be testing for?
 
While the product does not meet our competitive, modern standard of great engineering, I am happy to know that Cambridge went the distance to clarify the situation better. The same might not be said for numerous popular, audiophile-beloved companies.
 
Bryan T said:
I don’t hear any difference in noise from mine with or without a USB cable plugged in. What should I be testing for?
Click to expand...

Check if you hear noise, although it's probably inaudible as mentioned in the conclusion of the review:
  • "Performance is competent now for the class and transparent for most uses"
  • "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".
 
Geert said:
Check if you hear noise, although it's probably inaudible as mentioned in the conclusion of the review:
  • "Performance is competent now for the class and transparent for most uses"
  • "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".
Click to expand...
It is a quiet amp. Even with the volume maxed I struggle to hear any hiss more than a foot away from the tweeter. That is so far beyond how I use the amp (volume and distance to speaker) that it is basically an academic exercise. Unplugging the USB cable had no impact on the hiss in my setup.

Anyhow, with my simple setup (just a USB cable for digital and a phono preamp for analog), it works as expected.
 
formula 977 said:
THD+N is -120db and -110db with the so called usb problem. How is this a disappointment?
Pre out you have mostly triple 0 distortion. Measured properly the unit is more than competent.
Click to expand...
I agree let's not blow this out of proportion. The performance drop is negligible, no?

Anyway, Amir, could you please share the volume position of the CXA81 at max pre-out performance? It'd be great to know where I should limit the volume dial.
 
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formula 977 said:
THD+N is -120db and -110db with the so called usb problem. How is this a disappointment?
Pre out you have mostly triple 0 distortion. Measured properly the unit is more than competent.
Click to expand...

That's not how I meant that, but more along lines that there shouldn't be such a problem to begin with.

I mentioned in the other review that I'm happy with the CXA81 and if it turns out the measurements are correct that I don't regret the purchase.
 
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