Cambridge Audio Duo problem

[Digby]

My new Cambridge Audio Duo has arrived and it is definitely a significant improvement in noise and sound quality on the previous preamp, however there is a bit of a problem. I don't know if it is necessarily a problem with the Duo as such, but I am getting occasional distortion when using my Goldring 1042 cartridge. I checked the specs on Goldring's website and the cartridge is rather hot:

Sensitivity
6.5 mV +/-1.5 dB, 1 kHz @ 5 cm/sec

Perhaps the input is too much for the Duo to take. When I play records that distort with Goldring with a Nagaoka cartridge instead (5mv), then the distortion is not present.

Are there any recommendations as to a phono stage that can handle the Goldring cart? It's a nice sounding cartridge, but why would Goldring make the cartridge quite so high output in the first place.

 

[Morla]

So I remember a similar "problem" asking myself if the mV of the cartridge was to high but using the solo

https://www.audiosciencereview.com/...lo-phono-preamplifier-review.9666/post-352313

And my cartridge has higher output iirc. I did not notice distortion. But I am not a trained listener.

 

[Digby]

You wouldn't have to be a trained listener to hear the difference here, it is quite audible. I could provide a sound sample of the records when the distortion happens with the Goldring, then distortion free with the Nagaoka. It is interesting that your higher output cartridge is not presenting problems with the Solo though.

How does one go about figuring out whether any given phono preamp has enough headroom for x cartridge?

 

[Digby]

Nobody has any input as to how I can ascertain whether a phono preamp can handle a specific mv cartridge?

I am going to try the DJ ART pre and see if it presents the same distortion with the Goldring.

 

[Bob from Florida]

Nobody has any input as to how I can ascertain whether a phono preamp can handle a specific mv cartridge?

I am going to try the DJ ART pre and see if it presents the same distortion with the Goldring.

Cambridge claims the overload margin is greater than 30 db - according to specs listed on Music Direct. RIAA curve boosts treble - above 1000 HZ by as much as 20 db. Sounds like enough headroom except the maximum output was not specked. So, if the 30 db overload is to be believed then maybe the Goldring's output is clipping the power supply rails of the Cambridge. You have 2 possible overload scenarios. First is before the RIAA correction - >20 db headroom. Second is after RIAA - sufficient headroom for overall gain. The Cambridge may simply be limited in this respect. The Goldring is just too high output. The simple solution is to use a lower output cartridge. Clearaudio has a number of MM offerings that are 3.6 mv - for example. You could get a Sutherland KC Vibe - 48 volt power supply - that would probably work well with almost anything. Depends on how much audio "play" funds are available.

 

[TooProlix]

The issue may be the input sensitivity of your amp. The high output of the cartridge and the gain of the duo maybe too much for the amp.

I had a similar issue with a nagaoka mp110 and my preamp’s gain of 48db being too much for for my quad 77. The quad wants about 35db gain with a 5mv output cartridge- an art DJ pre sorted the issue out for me.

 

[abdo123]

Amir measured the Duo with double the input you specified. So i highly doubt the Cambridge is clipping.

I think the lower noise floor of the Cambridge just revealed a flaw somewhere else in the system.

 

[Sasha]

My old CA 651p stage clips my ancient ESI U24XL USB soundcard input (the level adjustment is in software and doesn’t actually attenuate the input voltage), so entirely possible the issue is at the amp end.

 

[cgallery]

@patient_ot had the same issue I believe with the exact cartridge, but the Mofi StudioPhono.

He found one of the Graham Slee units didn't exhibit the same distortion.

 

[Digby]

Thanks for the replies. Well, after purchasing the ART DJ Pre and using the adjustable gain, I get the same (distorted) result. I noticed that I don't get distortion with the Goldring on any new records. I think what may be happening is that the Goldring gyger stylus is picking up damage to the groove that the Nagaoka elliptical isn't, the distortion is an oscillation type sound in one channel only. I can provide a sound sample of the different styluses playing the particular record, if it is helpful in diagnosing the problem.

What is more interesting is my reaction to the ART DJ pre vs the Cambridge Audio. At first I thought the DJ was quite poor compared to the Cambridge Audio, but then I noticed that the Cambridge outputs a much louder signal (in fact, I have to keep my RME interface at minimal gain for anything save classical). When I compared a recording taken with the ART DJ pre and the Cambridge when the levels had been normalized, I was surprised to find there is very little difference. So little that it is not immediately obvious there is any discernable difference, I really can't be sure.

I can upload a comparison file from Audacity with the preamps playing a few different types of music, for comparison and guessing which file is which preamp (I will be doing this anyway for my own interest). It might be fun to see if people can guess which is which?

 

[abdo123]

Thanks for the replies. Well, after purchasing the ART DJ Pre and using the adjustable gain, I get the same (distorted) result. I noticed that I don't get distortion with the Goldring on any new records. I think what may be happening is that the Goldring gyger stylus is picking up damage to the groove that the Nagaoka elliptical isn't, although the sound is more of an oscillation type sound in one channel. I can provide a sound sample of the two styluses playing the particular record, if it is helpful in diagnosing the problem.

What is more interesting is my reaction to the ART DJ pre vs the Cambridge Audio. At first I thought the DJ was quite poor compared to the Cambridge Audio, but then I noticed that the Cambridge outputs a much louder signal (in fact, I have to keep my RME interface at minimal gain for anything save classical). When I compared a recording taken with the ART DJ pre and the Cambridge when the levels had been normalized, I was surprised to find there is very little difference. So little that it is not immediately obvious there is any discernable difference, I really can't be totally sure.

I can upload a comparison file from Audacity with the preamps playing a few different types of music, for comparison and guessing which file is which preamp (I will be doing this anyway for my own interest). It might be fun to see if people can guess which is which?

yes, the performance of the Cambridge Duo already surpasses any analog signal that could come out of a stylus, so in real-life applications you would be limited by the distortion and noise of the stylus.

however, i wouldn't play the lottery with phono stages, the good ones are the exception, not the rule.