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Review and Measurements of Cambridge DacMagic Plus

amirm

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#1
This is a review and detailed measurements of the Cambridge Audio DacMagic Plus DAC and "digital pre-amplifier." It is on kind loan from a member and costs USD $349 from the company itself or Amazon with Prime shipping. Researching the unit, it seems to have come out around 2012. Yet it seems to still be a current unit seeing how Cambridge still sells it.

The industrial design of the DacMagic Plus falls in line with the rest of Cambridge Audio products which is somewhat understated but fine looking nevertheless:

Cambridge Audio DacMagic Plus Review.jpg

This is called a digital preamplifier because it has multiple inputs and a volume control. There are also selectable output filters and a headphone out. I did not test the headphone output because it seems to have pretty high output impedance.

Back to volume control, it has a horrible feel. It is a rotary encoder meaning its value is digitized and used. As such, it has no minimum of maximum like an analog control would. That is fine but what is not fine is the stiff feel of it. Usually rotary encoders are rather lose with detents. Neither is here. Furthermore, I found that it jumps in rather coarse values.

Likewise, the on/off button is quite stiff. Fortunately you don't need to use it as often as the volume control.

No remote is provided which is sad as hard to use the volume control/inputs selection in a home system without it.

The back panel shows off the extensive connectivity of the DacMagic Plus:


Cambridge Audio DacMagic Plus Rear Panel Review.jpg

Great to see a set of balanced outputs in this price range and from a western brand. There are coax and Toslink inputs and outputs!

Power is provided by an external switching supply about twice the size of typical mobile phone adapters.

Interesting to see the ground lift switch. That might help with ground loops although the balanced XLR outputs should obviate the need for such.

I was impressed to see the ISO9001 marking for quality manufacturing and of course CE regulatory markings.

Measurements
As usual, we start with our dashboard using USB input:
Cambridge Audio DacMagic Plus Balanced Measurements.png


This is balanced output. As noted RCA out is a couple of dBs worse. Specification is more or less met with 0.001% THD+N distortion+noise. The figure is dominated by the third harmonic at 3 kHz to the tune of -100 dB. This puts the DacMagic at the threshold of tier 2 and 3 DACs tested:
Cambridge Audio DacMagic Plus Sinad Measurements.png


Dynamic range is pretty good and is worth 18.5 bits (111/6).

Cambridge Audio DacMagic Plus Dynamic Range Measurements.png


Intermodulation distortion shows the same positioning as THD+N does:
Cambridge Audio DacMagic Plus IMD Measurements.png


A bit higher noise level (downward sloping part of the graph) and distortion (rising part). Not quite as good as our best in class DACs but competent nevertheless.

Jitter measurements shows excellent results:
Cambridge Audio DacMagic Plus Jitter Measurements.png


Someone paid good attention to clean power and clock/reference signals. The only thing we see is noise which is benign.

Linearity is also unusually good:
Cambridge Audio DacMagic Plus Linearity Measurements.png


Likewise multitone output is as expected with nothing bad jumping out:
Cambridge Audio DacMagic Plus Multitone Measurements.png


THD+N versus frequency using wider bandwidth shows the higher noise floor noted earlier:
Cambridge Audio DacMagic Plus THD vs Frequency Measurements.png


There are three filter settings. I did all of my testing with Linear Phase. Here is its response:

Cambridge Audio DacMagic Plus Linear Phase Filter Measurements.png


Switching to minimum phase shows clearly clipping due to overshoot:
Cambridge Audio DacMagic Plus Minimum Phase Filter Measurements.png


It is best avoided.

Here is the steep filter:
Cambridge Audio DacMagic Plus Steep Filter Measurements.png


I measured the frequency response of the three using white noise to see the transition band response:
Cambridge Audio DacMagic Plus Filter Frequency Response Measurements.png


Both the linear and minimum phase filters have very low amount of out of band attenuation (just 19 dB). That will cause aliasing of the high-frequency components, polluting the high frequency components. Steep filter does a much better job (purple), providing nearly 60 dB of out of band reductions at 22.05 kHz (ideal would be infinite amount).

Conclusions
The Cambridge Audio DacMagic Plus gets a lot right here. It is nice looking with tons of features including balanced output. It is from a high-end audio brand yet it doesn't costs too much above budget produces. It is clearly well engineered with nothing other than clipping in minimum phase filter standing out. Its performance is probably limited by the Wolfson DAC chip landing in the lower middle of DACs tested.

The inclusion of XLR balanced output makes up for measured results to some extent and pushes me to put the DacMagic Plus on my recommended list.

EDIT: Headphone measurements here: https://www.audiosciencereview.com/...s-of-cambridge-dacmagic-plus.6887/post-153184
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WondrousHippo

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#2
Thanks for measuring this! I have been curious to see how this one would perform. The SINAD is a bit lower than I’d like, but at least it has no major deficiencies. I do wish that it was on par measurement-wise with the KTB and SU-8 though!
 

amirm

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#6
I also think minimum phase clipping is a non issue unless one likes to listen to square waves.
What value does it have if you don't feed it squarewave???? ;) :)
 

soundwave76

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#9
I had this some years ago when I had analog Genelecs, because I valued the XLR outputs a lot. Had no complaints about the sound, but the feeling of the volume knob was indeed poor.
 
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#10
I have the Cambridge dac magic plus with a an aftermarket linear psu , whether that does any good im not sure , but it does sound better (maybe placebo). im also using jds lab atom , will i be able to notice difference upgrading the dac magic to topping d50
 

graz_lag

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#12
I have the Cambridge dac magic plus with a an aftermarket linear psu , whether that does any good im not sure , but it does sound better (maybe placebo). im also using jds lab atom , will i be able to notice difference upgrading the dac magic to topping d50
I agree with @Veri and I enphasize : "nooooo" ... ;)

Upgrading the stock PSU into a nice linear one is always a good step from an engineering point of view, whether the results of that upgrade are audible that is a totally different subject ...
 

BYRTT

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#14
.....will i be able to notice difference upgrading the dac magic to topping d50
A note is with objective eyes it looks you should set filter to steep to get out of band 60dB reduction and agree @Veri you probably should be happy having a very good DAC there.

Not shure have seen here at site how d50 looks for out of band but think we get a hint that's >75dB using default filter "Apodizing" because that is what Khadas TB perform in @amirm test for MARCH audio dac1 and all tree of them use same DAC chip and d50 have menu to set whatever filter. DacMagic Plus looks great in benchmark here a lower noice floor and better reduction of out of band is probably what d50 will bring.
 

Veri

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#15
i got a dragonfly black too , and the upgrade from it to the dac magic was quite noticable. atom was alot better than dac magic headphone out too. But i guess 98 db sinad is plenty for just spotify....
This dacmagic with the atom definitely seems like a sweet headphone rig :) !
 

pos

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#16
The 1kHz measurement is rather clean compared to most modern mobile ess dacs like the su8 or d50: nothing stands out beside relatively low orders harmonic distortion.

This does not show in the SINAD figure but should deserve some attention of its own.
 

graz_lag

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#17
i got a dragonfly black too , and the upgrade from it to the dac magic was quite noticable. atom was alot better than dac magic headphone out too. But i guess 98 db sinad is plenty for just spotify....
Spotify free is @ 160kbps max with lower variable rates depending the available bandwidth, so no worry here ... neither within the 320kbps subscription scenario ...

If you do not use all its digital preamp features, yes why not selling your dac magic plus then replacing it with the D50, as most likely you're not going to add money. (The D50 is @ $212 from Shenzhen Audio.) Testing new units is always fun.
 

pma

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#18
Clipping with the Minimum phase filter are the intersample-overs (analog), square wave to be -2dBFS and less to avoid this. Minimum phase filter has higher initial overshoot in its step response, but no pre-ringing. It is questionable if audible clipping with a music signal would occur.
 

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