My Bad Luck With Phono Preamps

[computer-audiophile]

As I recall, the onus is on the RFI "emitter" not to interfere --

Yes, should be that way. (In a ideal world)

 

[AnalogSteph]

As I recall, the onus is on the RFI "emitter" not to interfere -- at least under US regulations, and the last time I looked

Outside the officially assigned frequency ranges, that is. A WiFi accesspoint is invariably going to emit RF on the customary 2.4, 5 and maybe 6 GHz bands, that's its job. As long as radiated power is within the limits set by local regulations, it is not at fault if another device decides to be the princess on the pea and take issue with its perfectly legal emissions.

A fair few ham radio operators have had to RF-proof poorly constructed TV sets in the neighborhood over the years in very similar scenarios. At least you had someone with a real chance of fixing the issue at hand in these cases.

RF ingress protection in phono stages varies wildly. Some of the best I've seen were in Technics amplifiers. Classic bipolar audio opamps with modestly low voltage noise (as well as vintage audio power amplifier ICs) tend to be relatively sensitive to RF demodulation due to low input stage tail current. The LM4562 seems to be downright allergic, possibly its bias current cancellation is too blame.

Some issues with unwanted common-mode emissions did slip through the cracks though. Most plasma TVs are giant direct radiators in the AM and lower shortwave bands and were only legal due to prevalent testing methods (it took Panasonic until 2009 to make ones with functional shielding, at which point the technology was already on its way out). Although honestly the Sony Trinitron my parents used to have before that was pretty bad in terms of shortwave interference as well. Never a shortage of fraudulent SMPS' either. Nowadays I live in an apartment complex... where does one even begin?

 

[mhardy6647]

Outside the officially assigned frequency ranges, that is.

Good point.
I was a bit too elliptical in my earlier post (which doesn't really sound like me, does it?)

PS Note that I have actively resisted the temptation to use any ellipses in this reply!

 

[Jim Creek]

Someone else mentioned some grounded foil. I've used that successfully a couple times. Just a cardboard panel wrapped in foil and grounded. In one case a Mac Mini was causing noise. Put the foil between the two and it went away. Later moved the TT and phono several feet away. Another time put the foil on the underside of the shelf above the phono pre and it got rid of RFI from a DAC.

Thanks for your ideas. I created an aluminum foil covered box for my Art. It works! The Art is completely silent now. The foil must be grounded to the ground screw on the Art though. It was a fast and easy solution. The Art is immune from RFI and evil controlling Alien messages.

It looks ugly, but the unit is hidden away inside a cabinet with the doors closed.

 

[mhardy6647]

Thanks for your ideas. I created an aluminum foil covered box for my Art. It works! The Art is completely silent now. The foil must be grounded to the ground screw on the Art though. It was a fast and easy solution. The Art is immune from RFI and evil controlling Alien messages.

It looks ugly, but the unit is hidden away inside a cabinet with the doors closed.

View attachment 326718

Now you know how the tinfoil beanie crowd got their start...

 

[computer-audiophile]

Thanks for your ideas. I created an aluminum foil covered box for my Art. It works! The Art is completely silent now. The foil must be grounded to the ground screw on the Art though. It was a fast and easy solution. The Art is immune from RFI and evil controlling Alien messages.

It looks ugly, but the unit is hidden away inside a cabinet with the doors closed.

View attachment 326718

Great installation, glad it worked.
Thank you for taking a picture.

 

[Godataloss]

Thanks for your ideas. I created an aluminum foil covered box for my Art. It works! The Art is completely silent now. The foil must be grounded to the ground screw on the Art though. It was a fast and easy solution. The Art is immune from RFI and evil controlling Alien messages.

It looks ugly, but the unit is hidden away inside a cabinet with the doors closed.

View attachment 326718

You should begin marketing your Audio Enhancement Shroud as soon as possible. How does it hold up against gamma rays?

 

[Jim Creek]

You should begin marketing your Audio Enhancement Shroud as soon as possible. How does it hold up against gamma rays?

Aliens can no longer control my phono preamp.

 

[anmpr1]

Thanks for your ideas. I created an aluminum foil covered box for my Art. It works!

Excellent! Old timers will probably remember audio 'reviewer' Enid Lumley who was part of Harry Pearson's circus back in the day. In a way, Enid was one of the few worth reading, simply because she was so 'over the cliff'. At first you couldn't tell if she was serious. At least I couldn't. In fact, I thought Enid was actually Harry, writing under a nom de plume, in an attempt to be self-deprecating and humorous. Until I realized that Pearson had no sense of humor, but only a sense of self-importance.

Anyhow, Enid's thing was 'stray radiation' emanating from household electrical motors. In one article she talked about wrapping her refrigerator in tin foil, which evidently tightened up the bass and firmed up the imaging. Or something. I always wondered how she got the beer out, with the box all wrapped up in foil.

 

[golio]

Mon préampli phono Schiit Mani 2 a développé un problème au bout d'un an et demi, toujours sous garantie. Le canal gauche est devenu dominant tandis que le canal droit est devenu très faible. Bien sûr, cela a déplacé la scène sonore vers la gauche. J'ai essayé de nombreuses configurations avec des câbles, des cartouches d'écouteurs, etc. J'en suis arrivé à la conclusion qu'il s'agissait du préampli phono.

Je l'ai renvoyé pour réparation sous garantie. Il est revenu au bout de trois semaines. La facture indiquait que les amplis opérationnels gauche et droit avaient été remplacés. Je l'ai essayé et il avait le même problème, canal gauche encore trop dominant.

Plutôt que de renvoyer le Man 2 une seconde fois, j'ai acheté un préampli phono Art Precision pour faire une comparaison, 79$ sur Amazon. The Art a joué parfaitement, les canaux gauche et droit équilibrés, avec une excellente acoustique…...à la première écoute.

Puis j'ai remarqué un léger bruit dans l'Art. C'était un bruit rapide de « putt… putt… putt » venant de l'Art. Augmenter le gain sur l'Art ou augmenter le volume sur mon préampli Topping Pre90 a augmenté le bruit.

Cet Art Pre est la version la plus récente avec une alimentation 12 V CC. Je l'ai essayé en utilisant un chariot MC Denon DL103 et un chariot MM AT95ML. Le bruit était là avec les deux chariots. J'ai renvoyé l'Art Precision à Amazon. Ils vont le remplacer gratuitement par un autre Art Precision.

Je ne sais pas quoi faire du Mani 2. La facture contenait un tas de tests avec des cases cochées. Le technicien Schiit pense que c'est bien. Schiit croira-t-il qu'il est toujours défectueux ? Est-ce que cela vaut la peine de dépenser 15 $ supplémentaires pour le renvoyer ? Je ne sais pas

j'aimerais savoir pourquoi vous avez besoin d'un ampli phono ? est-ce à cause du type de cartouche que vous avez soit MC ou MM ?

 

[Jim Creek]

j'aimerais savoir pourquoi vous avez besoin d'un ampli phono ? est-ce à cause du type de cartouche que vous avez soit MC ou MM ?

I use a MC, the Denon DL103. Yo uso una MC, la Denon DL103.

 

[golio]

J'utilise un MC, le Denon DL103. Vous utilisez un MC, le Denon DL103.

vous savez quel MC j'utilise ? comment faites - vous pou savoir ce renseignement ?

 

[golio]

je le savais même pas moi-même :facepalme:

 

[Jim Creek]

Nvous savez quel MC j'utilise ? comment faites - vous pou savoir ce renseignement ?

The Art Precision phono preamp is compatible with both MC and MM cartridges. I use a Denon DL 103 and an Audio Technica AT95ML with the Art Precision phono preamp. It's a very good phono preamp except it is not shielded foe RFI.

Le préampli phono Art Precision est compatible avec les cellules MC et MM. J'utilise un Denon DL 103 et un Audio Technica AT95ML avec le préampli phono Art Precision. C'est un très bon préampli phono sauf qu'il n'est pas protégé contre les RFI.