Cambridge Audio Duo Phono Stage Review (Updated)

[wemist01]

I think I've said this before but that's a great record you have as your avatar. Have you heard this, by another Sun Ra collaborator?

I remember grabbing both LPs when they were reissued around 20 years ago (wow) and I was working at a record store.

I missed it- love the rec- I will check that out!

 

[mightygrey]

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

Is that a function of the limitations of vinyl rather than the headphone stage?

 

[Rja4000]

Ticks and pops may be worse sounding than otherwise.

This topic still confuses me.
Would you have some background article about this ?

I'd like to learn and understand it better.

 

[amirm]

Is that a function of the limitations of vinyl rather than the headphone stage?

The headphone amp itself. From what I recall, it is low power with high impedance.

 

[amirm]

This topic still confuses me.
Would you have some background article about this ?

I'd like to learn and understand it better.

The best reference I have is from this paper: https://www.aes.org/e-lib/browse.cfm?elib=2623

It is written by the famous Tom Holman. In there he computes the worst case level created by a cartridge:

 

[AudioSceptic]

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.

So, those super long Canare cables have nothing to do with the loading of your cartridge?!

 

[AudioSceptic]

The headphone amp itself. From what I recall, it is low power with high impedance.

The impedance was actually good.

----
Switching to headphone amplifier, the outcome is disappointing. Here it is with 300 Ohm load:

Even when you force the unit with far higher levels than any cartridge provides, you only get 10 milliwatts of power. My standard is 100 milliwatts here. With typical cartridges, you are likely to get single digit output power in milliwatts. Better have a sensitive headphone to get much value here.

Kind of odd is how quickly the graph flattens. Seems to be high level of noise there to dominate that way.

The situation is not much better with 33 ohm load:

You will be lucky to get 10 milliwatt output with any real cartridge.

There is good news however in the form of low output impedance:

++++

 

[sarumbear]

I just realized for the first time that the phono preamp is another fundamental limitation on the SQ of vinyl. So, even everything else in your chain is perfectly transparent (the disc, the cartridge, etc.) the best SINAD you’re ever going to get with MC is ~-63 dB. That’s even worse than most speakers above ~300 hz. Am I missing something? What do measurements of vinyl test recordings deliver in best-case systems?

How do you measure the SINAD of a speaker, a passive device?

 

[mightygrey]

The headphone amp itself. From what I recall, it is low power with high impedance.

So, potentially no problem for more sensitive (+100dB)/high impedance headphones, eg HD600/HD800s if you're using vinyl as a source?

 

[MediumRare]

How do you measure the SINAD of a speaker, a passive device?

Well, perhaps THD is the relevant measurement for the speakers since there is effectively no noise contributed by them directly, correct? So looking at the entire chain, noise will be coming from the source, the cartridge, the amplifiers, and the cables; distortion from all (excl. cables) plus the speakers. But if the preamp has worse THD than the rest that will be the primary source of distortion whereas often the speakers are the weak link, correct?

 

[sarumbear]

Well, perhaps THD is the relevant measurement for the speakers since there is effectively no noise contributed by them directly, correct? So looking at the entire chain, noise will be coming from the source, the cartridge, the amplifiers, and the cables; distortion from all (excl. cables) plus the speakers. But if the preamp has worse THD than the rest that will be the primary source of distortion whereas often the speakers are the weak link, correct?

This was not answer to the question.

 

[andrewskaterrr]

So, those super long Canare cables have nothing to do with the loading of your cartridge?!

I don’t think so, but I’m new to this? My Preamp is right next to my TT.

Cartridge > 3ft Technics stock cables > Phono Preamp 47kohm > 40ft Canare > Pre/Pro.

 

[MediumRare]

This was not answer to the question.

If you're getting stroppy, the answer is you use REW to compare the output of the speaker with the input, subtracting room noise.

 

[sarumbear]

If you're getting stroppy, the answer is you use REW to compare the output of the speaker with the input, subtracting room noise.

Bravo. That is how you measure the SINAD of a speaker —not!

I’m not stroppy. I’m simply pointing to your sloppy use of a parameter. It’s up to you to learn.

 

[MediumRare]

Bravo. That is how you measure the SINAD of a speaker —not!

I’m not stroppy. I’m simply pointing to your sloppy use of a parameter. It’s up to you to learn.

Teach us, please.

 

[sarumbear]

Teach us, please.

To clarify, I was commenting to your following post.

I just realized for the first time that the phono preamp is another fundamental limitation on the SQ of vinyl. So, even everything else in your chain is perfectly transparent (the disc, the cartridge, etc.) the best SINAD you’re ever going to get with MC is ~-63 dB. That’s even worse than most speakers above ~300 hz. Am I missing something? What do measurements of vinyl test recordings deliver in best-case systems?

SINAD is a parameter of active devices as passive devices generate no noise.

 

[MediumRare]

To clarify, I was commenting to your following post.

SINAD is a parameter of active devices as passive devices generate no noise.

And that’s why I clarified that THD was actually the relevant measure for a speaker.

 

[sarumbear]

And that’s why I clarified that THD was actually the relevant measure for a speaker.

My comment was to your earlier post, which is reposted, where you said SINAD.

 

[LTig]

My comment was to your earlier post, which is reposted, where you said SINAD.

SINAD combines noise and distortion.

 

[sarumbear]

SINAD combines noise and distortion.

As a speaker has no noise, SINAD is the wrong parameter. You do not measure the SINAD of a speaker.

That is the point I’m making.

Anyway, I’m off as we have polluted a review thread enough already. If you disagree please start a new thread and invite me.