Cambridge Audio Duo Phono Stage Review (Updated)

[andrewskaterrr]

Nasty. Can’t say what it is. Needs to be measured.

I’ll double check the solder joints this weekend if I can.

 

[andrewskaterrr]

Nasty. Can’t say what it is. Needs to be measured.

I have a multimeter, would I be able to use it somehow to find the issue? I’m a noob with electronics though.

 

[SD2KING]

Thank you. Exactly the device I need! Guys, how would you make this wireless to connect it with the preamp that can't sit next to it? Any wireless repeater you'd recommend that will not impact sound quality too much?

This idea might solve my issue of not having a line-in on the DMP-A6 to connect a phono stage to. It had occurred to me, but it didn't see the point of converting analogue to digital and then reconverting it back to analogue.

My wife would actually prefer to have the turntable on a different piece of furniture; 5 meters away from where audio equipment is. So this might actually tick that box too.

I have my tuner and turntable in a room separate from my newer, main system. My main system has a WiiM Pro for streaming Roon, Qobuz, TIDAL, etc. My turntable and tuner are connected to a vintage Adcom GFP-555 preamp with the tape monitor output going to an Amazon Link preamp that used to be in my main system. The WiiM and the Amazon Link can be set up as an Echo group. So it goes turntable/tuner cabled to Adcom preamp cabled to Amazon Link wireless to WiiM Pro connected by optical to my main integrated amp. Even with the turntable source going through an ADC to DAC process the sound is very good to my ears when playing well-recorded LPs in good condition. I play vinyl and CDs mostly for older jazz reissues that aren't available through streaming services. In some case I prefer the mastering on those reissues to digital streams.

I also have a vintage Adcom GCD-700 5 CD changer cabled to the Amazon Link's coax in. That's a pure digital path from the CD changer to Amazon Link to WiiM Pro to my main integrated amp. I can't hear the difference between that and direct 16/44.1 streaming.

Might be pricier than you want to do from scratch, but worked well for me since I had already retired my Amazon Link preamp.

This sounds pretty involved; lol. We don't have any amazon devices, so want to keep it as "clean" as possible.

 

[Laserjock]

I have a multimeter, would I be able to use it somehow to find the issue? I’m a noob with electronics though.

Tighten the screw terminals as shown in these pics? Blue terminal blocks?

**Unplug the power of course when doing anything inside

 

[MediumRare]

Count yourself lucky. Mine is above that, more like 50dB. There is the airport in the next city, the train station about 1 km away, the train tracks 200m away, the Autobahn maybe 500m away, the school near me.
I looked up the situation in other cities, it's not rare to have more than 60dB sustained background noise.

My point is this, we all know that records and the technology around it is limited, but it's not as bad as some think it is.

My main listening room is in my finished basement family room, 27 x 17 x 10 feet, perfect 7.5 foot equilateral triangle 18" from the front wall, concrete foundation on three sides, windows only above ear level. When I do EQ checks with REW I can see the El train on the graph before I hear it faintly, noise goes from 20 to 40 dB for about 10 seconds. But with music at 80 dB totally impossible to notice.

 

[Thomas_A]

I have a multimeter, would I be able to use it somehow to find the issue? I’m a noob with electronics though.

Yes there are some points to measure. Check troubleshooting at muffsy.

 

[Laserjock]

I have a multimeter, would I be able to use it somehow to find the issue? I’m a noob with electronics though.

Did you build this? https://www.muffsy.com/muffsy-pp4.html

 

[andrewskaterrr]

Why don't you guys start a muffy thread? Not being mean, thread seems to be drifting away from Duo ....

I was going to suggest that actually. I’ll make a post.

 

[andrewskaterrr]

Did you build this? https://www.muffsy.com/muffsy-pp4.html

Yes that’s what I built.

 

[andrewskaterrr]

Yes there are some points to measure. Check troubleshooting at muffsy.

Muffsy Phono Preamp PP-4 question/help

Im here to discuss two different topics. 1. I’m hoping that we can have some measurements taken of the Muffsy PP-4. 2. I’m having an issue where mine started popping and making noise, I believe only in the Left channel. It worked for about 2 years without issue, then started doing this after...

www.audiosciencereview.com

 

[LTig]

Sinad measurement of a phono stage must always include the output impedance of the cartridge.
We are way down at the fundamental noise source , the thermal noise. So a mc phono amp need a pickup to lower the hf noise. 10 ohm with mc pickup vs 200 ohms without

The MC measurement (dash board) was done with 20 Ohm source impedance, so not too far from typical low output MCs. OTOH I don't konw the frequency dependency of a MC output impedance. The APs 20 Ohm are certainly constant over frequency.

 

[roog]

Good to see that the mainstream modest cost Cambridge kit does well, I have one of their phono pre amps from around 2017/18 and it works well I wonder if the duo shares a similar phono stage?

 

[mightygrey]

Did you test the headphone out?

 

[amirm]

Did you test the headphone out?

Not this time. It is on the old review and was rather poor.

 

[MyCuriosity]

This is an updated review of the Cambridge Audio Duo phono preamplifier. It is on kind loan from a member and costs US $349.
View attachment 301088
The Duo has a solid build and is attractive to boot for its price. Back panel shows independent sets of inputs for moving magnet and coil cartridges:

View attachment 301089

I like the inclusion of balance control and built-in power supply.

The original version was tested very early on when I had gotten into phono stage testing. My protocols have evolved since then making it hard to compare those measurements to current phono stage reviews.

Cambridge Audio Duo Measurements
It was challenging to reduce ground loops in both channels. After some messing around, I got close to optimal on both channels:
View attachment 301090
This lands the Duo essentially at the top of the class:

View attachment 301091

We still have that odd spikes around 19 kHz. Moving coil input naturally has lower SINAD due to much higher gain:
View attachment 301093

Distortion is vanishingly low when measured without noise:
View attachment 301094

RIAA equalization is essentially perfect in both modes:
View attachment 301095

Headroom could be a bit better:
View attachment 301096

Fortunately the same performance remains up to 10 kHz:
View attachment 301097

Conclusions
While the cost has gone up $50, the Duo is still reasonably priced for a solid package both physically and electronically. The only miss is with respect to overload due to output maxing out at 10.5 volts. Otherwise we have excellent frequency response and state of the art in distortion in a phono stage.

My excellent recommendation rating for Cambridge Audio Duo remains.

---------
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/

What would be the expected impact in sound quality due to the limited overload?

 

[amirm]

What would be the expected impact in sound quality due to the limited overload?

Ticks and pops may be worse sounding than otherwise.

 

[USER]

Well I think I have 35-40ft of Canare L-3CB which is 55 pF/m, that puts me well above 200pF

Yikes! And the sound is...good??? I'd love to know how that measures. Honestly, that's the most extreme case I've ever heard of.

Have you considered having the phono pre-amp closer to the turntable and then running the long cables from it? You should at least compare how that sounds against your current set-up. MC cartridges are far less load dependent and could sound right with what you have, though it is still an extreme case.


Wait...could that be causing your problems???

 

[MyCuriosity]

Ticks and pops may be worse sounding than otherwise.

Thanks a lot.

 

[andrewskaterrr]

Yikes! And the sound is...good??? I'd love to know how that measures. Honestly, that's the most extreme case I've ever heard of.

Have you considered having the phono pre-amp closer to the turntable and then running the long cables from it? You should at least compare how that sounds against your current set-up. MC cartridges are far less load dependent and could sound right with what you have, though it is still an extreme case.


Wait...could that be causing your problems???

Oh sorry, I'm using the stock Technics ~3ft cable + ground wire to get to the Phono Preamp, then it's 40ft RCAs from Preamp to Processor.

 

[maxwell3e10]

I find it interesting that SINAD plus gain is about 125dB (124 and 126 for two types of inputs). This is roughly the same as AP's best SINAD. I wonder how the low-level test voltage is generated by AP? Is it limited by the intrinsic noise level of the AP's output? It might be interesting to test with an external resistive attenuator. If my estimates are right, these measurements of the best microphone amplifier noise level come out to about 4 nV/sqrt(Hz) at 1 kHz. That's not exactly state of the art for a low input impedance amplifier, should be 1 nV/sqrt(Hz) or below.