Review and Measurements of Cambridge Audio Duo Phono Preamp

[rwortman]

Dynamic range compressors and expanders are different circuits and are not part of phono preamps. Whatever dynamic range is on the record and produced by the cartridge will make it through the preamp unless the preamp is overloaded. The main affect any phono preamp will have on actual dynamics is the noise floor. As others have stated here, much of audio perception can be explained by frequency response. I suspect phono preamps that are described has having great dynamics are very quiet and/or have a frequency response error such as a modestly accentuated upper bass.

 

[DWI]

Signal to noise and dynamic range. Usually, the medium and the cartridge are the choke points.

Surface noise on vinyl would probably fail a DAC test, and clean records and stylus go a long way. In my recent experience the cartridge is not the choke point, it's the phono stage. I have two very resolving cartridges (different brands - same stylus), and with both of them there was marked difference in dynamics between three phono stages, all with very low noise levels. Incidentally, the best was not the most expensive.

 

[DWI]

Dynamic range compressors and expanders are different circuits and are not part of phono preamps. Whatever dynamic range is on the record and produced by the cartridge will make it through the preamp unless the preamp is overloaded. The main affect any phono preamp will have on actual dynamics is the noise floor. As others have stated here, much of audio perception can be explained by frequency response. I suspect phono preamps that are described has having great dynamics are very quiet and/or have a frequency response error such as a modestly accentuated upper bass.

It's not frequency response because the very obvious difference in speed and dynamics is well within the range of any half-baked amplifier, and the only change in the system is the phono pre-amplifier. None of the three phono preamplifiers have published measurements.

 

[SIY]

Surface noise on vinyl would probably fail a DAC test, and clean records and stylus go a long way. In my recent experience the cartridge is not the choke point, it's the phono stage. I have two very resolving cartridges (different brands - same stylus), and with both of them there was marked difference in dynamics between three phono stages, all with very low noise levels. Incidentally, the best was not the most expensive.

Well, basic physics limits the cartridge signal to noise to 70dB or so, and that’s before anything touches the record surface. So no, dynamic limitation by the phono stage is highly unlikely unless it’s heinously bad.

 

[rwortman]

It's not frequency response because the very obvious difference in speed and dynamics is well within the range of any half-baked amplifier, and the only change in the system is the phono pre-amplifier. None of the three phono preamplifiers have published measurements.

Those very obvious differences in perceived speed and dynamics are almost always about frequency response. I don’t know a half baked amplifier has to do with the question.

 

[anmpr1]

For me, once you get past all the OTHER stuff that brings vinyl down, it pretty much always comes down to noise/hum/hiss. Especially with MC. I use a 9V battery powered MC step up from the early '80s (based on Marshall Leach's Audio project)--very sensitive to placement. Move it an inch here or there, up or down, toward or away from the preamp, and noise may increase significantly.

The newer stuff is probably better, in that regard.

You get used to it. At moderate volume it's never an issue, and in any case it is masked by the record. When switching over to digits it's like Mr. Clean entered the room.

 

[DWI]

For me, once you get past all the OTHER stuff that brings vinyl down, it pretty much always comes down to noise/hum/hiss. Especially with MC. I use a 9V battery powered MC step up from the early '80s (based on Marshall Leach's Audio project)--very sensitive to placement. Move it an inch here or there, up or down, toward or away from the preamp, and noise may increase significantly.

The newer stuff is probably better, in that regard.

You get used to it. At moderate volume it's never an issue, and in any case it is masked by the record. When switching over to digits it's like Mr. Clean entered the room.

I've been upgrading my phono chain. One option I seriously considered were a pair of passive Stevens & Billington step-up transformers. Very high quality and technology that has barely changed in many decades. Plenty of people take that route, but they tend to be specific to the loading of cartridges.

My phono had a separate power supply that is distant and well shielded. The vinyl revival has brought on a lot of really good and very quiet m/c phono amplifiers. There was always the EAR 834P, made for almost 50 years and a favourite design for the DIY boys. Simple and elegant. I had the upgraded EAR Phonobox and it was dead quiet, very enjoyable, but lacked a bit of pace. All the same, great value.

I get the Mr Clean, comment, some may say more sterile than clean, vinyl just has that something it's so difficult to explain. I was streaming something last night and after 10 minutes just had to get out the vinyl version and play that instead.

Good vinyl playback can be visceral and tangible, unlike some digital, it's not a matter of frequency response as others have suggested.

I find the irony is that digital audio equipment is easy to measure (and much of it is), but often the differences are well below audible levels, whereas vinyl playback equipment is often not measured, or not measured properly, but is very easy to tell apart by listening.

The fact that with many phono amplifiers you can adjust the gain on-the-fly to reduce noise levels to an acceptable level makes measurements less important.

The problem with ASR's best rated Cambridge Audio phono is that, amongst other things, it is a bit short on m/c gain (60db) and you can't adjust it. It is designed to be quiet within its limitations for a very cost-effective device.

 

[MaxBuck]

Without in any way depreciating the interests of vinyl buffs, looking for superior phono preamplifiers seems a lot to me like genetically modifying horses, the better to pull your buckboard.

 

[rwortman]

Without in any way depreciating the interests of vinyl buffs, looking for superior phono preamplifiers seems a lot to me like genetically modifying horses, the better to pull your buckboard.

More like genetically modifying horses to go faster in a horse race despite the fact that some folks don’t understand why anyone would race horses when cars exist.

 

[anmpr1]

Without in any way depreciating the interests of vinyl buffs, looking for superior phono preamplifiers seems a lot to me like genetically modifying horses, the better to pull your buckboard.

What you are looking for in a phono preamp is low noise, low distortion, and decent RIAA EQ. What you are looking for in an animal to pull your wagon is stamina, and the ability for it to do what you 'tell' it to do (stop, go, follow the road).

You don't need a fifty thousand dollar phono preamp in order to enjoy records. Just like you don't need a thoroughbred horse to pull your wagon. In fact, the old grey mare, or even a mule, will likely work just as well, if not better.

The difference between hitching up your wagon in order to go in to town once a month for supplies, and the high-end record crowd, is that if you showed up at Sam Drucker's General Store with Fusaichi Pegasus pulling your wagon, people would think you were crazy, laugh at you behind your back, and probably wouldn't want to hang with you. However, if you spring for a Boulder 2108 phono preamp, the 'high-end' analog crowd will be jealous, and Fremer will invite himself over for beers, whether you want him to show up, or not.

 

[DWI]

You don't need a fifty thousand dollar phono preamp in order to enjoy records. Just like you don't need a thoroughbred horse to pull your wagon. In fact, the old grey mare, or even a mule, will likely work just as well, if not better.

No one needs anything, but in my recent (last week) experience comparing three low-noise phono amplifiers side by side, there were clear differences in speed and resolution.

Vinyl v digital is the single most pointless discussion imaginable, even for those of us who use both in equal measure.

 

[SIY]

No one needs anything, but in my recent (last week) experience comparing three low-noise phono amplifiers side by side, there were clear differences in speed and resolution.

Vinyl v digital is the single most pointless discussion imaginable, even for those of us who use both in equal measure.

“Speed and resolution” aren’t really a function of the electronics per se, but more of frequency response. A bit of EQ to get it the same *with the cartridge attached* will remove sound differences.

 

[anmpr1]

2) No one needs anything..., 1) there were clear differences in speed and resolution.

3) Vinyl v digital is the single most pointless discussion imaginable, even for those of us who use both in equal measure.

As the Bard wrote: We must speak by the card or equivocation will undo us. So, with that in mind, and since you are such a stickler in the semantics department, I'll respond in kind...

1) 'Speed and resolution' are pretty nonsensical criteria in the context of an electronic circuit.

2) As far as no one 'needing' anything? If you are going to nit pick my way of writing loosely, and in a rather tongue in cheek manner, then I'll nitpick your own statement, by telling you that some human things are definitely in the 'need' category. Although I agree with you that hi-fi gear is really not a needful thing, at least within a greater human context.

3) Discussing this stuff is what the forum is all about. If you think it is pointless, why are you responding with your own opinions?

 

[Laserjock]

What would be the SINAD at 5mV for this unit?
Waiting on the Mani 2 to see how it does.

 

[flz]

Good "value to performance" for sure. Not so sure about their durability. I owned their flagship units at the time. The 851A amp and 851C DAC/CD Player. Bought in 2015 (1600€ each) and issues started few month later. The 851A got VERY warm and sometimes suddenly turned off due to the heat... I wasn't able to listen to it at high volumes for more than an hour. Then the 851C showed serious problems. I started to notice a very audible noise in right chanel (both XLR and RCA) and it gone worse weeks after weeks. I wanted to use some warranty but neither Cambridge or PPL Audio (Cambridge retailer in France) accepted to fix this for free. And asked me 300€ to repair the output stage... I ended by sold both units at a broken price to a guy who was saying he could fix the issue himself.
If this is the kind a quality control (and support) they provide for their flagship units... Then I'm not going to buy anything from them anytime soon...

I would consider a Cambridge DAC or DAC/Streamer but also had a horrible experience with the 851A amp. It sounded good while it worked but died after 3 years of ownership (bought brand new from dealer). And the warranty I got was only 2 years so it was a total write-off. That really put me off on CA. Plus I also had a friend who had serious reliability issues with CA Cd players.

 

[TheBatsEar]

Had one on my wanted list for years. Scored one for 170€ just now. Wohoo!
Finally i can hook my record player to the MiniDSP.

 

[Chester]

Can anyone help me understand what’s going on with my Cambridge Duo.

I have it plugged into an RME ADI-2 Pro. I noticed that MC mode had a lower noise floor that MM. MC was about 80dB while MM was 74dB. With my limited knowledge, I had expected MM to be quieter?

I disconnected everything and tried just the Duo and RME connected, to see if anything changed. It did not.

Is this expected or could something be broken?

Thanks

Chester

 

[TheBatsEar]

I have it plugged into an RME ADI-2 Pro.

I need me to get one of those, but they are rare in the used markets here

I noticed that MC mode had a lower noise floor that MM. MC was about 80dB while MM was 74dB. With my limited knowledge,

I don't understand, 74dB of noise (MM) is 6dB smaller than 80dB of noise (MC)?

 

[TheBatsEar]

BTW, has someone found a way to disable the auto-off feature? Annoys me a bit, i always start to play the record and then wonder why there is no music.

 

[abdo123]

What would be the SINAD at 5mV for this unit?
Waiting on the Mani 2 to see how it does.

6dB less.