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AC power anomalies disrupt only phono stage?

Despite the insertion of a Power Conditioner (Shindo Mr T) for the turntables and preamp in my system……when the street’s power supply is corrupted, the phono stage of my Halcro DM10 preamp is rendered virtually unlistenable?
At the same time…..the line-level inputs (like Tuner and Aux) are unaffected. In fact the sound through the TV (connected to Aux)…..is quite sublime on movie scores.

I am baffled at what could possibly cause the phono-stage to ‘implode’ at these times…..whilst leaving untouched the high-level stages?
128x128halcro
10 responses Add your response
zd542
5,339 posts
 
"when the street’s power supply is corrupted, the phono stage of my Halcro DM10 preamp is rendered virtually unlistenable?"

How do you know that's true? I'm not saying that you're wrong, only that the problem may lie somewhere else. There's a pretty good chance that if the AC is as bad as you say, it would most likely effect all your other components to some degree. I can think of several things that may be wrong with your TT and related components that may be the cause of your problem, as well.
dover
2,243 posts
 
Halcro - it would help if you described what you mean by unlistenable. What does it sound like.
halcro's avatar
halcro OP
2,664 posts
 
Dover,
The soundstage completely collapses with little width and no depth.
The highs become brittle and emphasised at the expense of the midrange and the bass has all the characteristics of an 'out-of-phase' connection.
In other words.....it sounds like the worst of digital!
Thankfully they have stopped messing with the mains down the street.....and 'normal' transmission has been restored.
But it confounds me as to how only the phono-stage can be affected whilst the AUX can sound as beautiful as ever at these times?
nandric's avatar
nandric
4,086 posts
 
Dear Henry, Ever thought about to use a battery powered
pre? I have never such problems with my ASR Basis Exclusive.
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rauliruegas
13,052 posts
 
Dear Halcro: +++++ " In other words.....it sounds like the worst of digital! " ++++++

or the worst of analog.

Halcro, as I told you maybe is time to an up-date. IMHO, that's a design problem on the DM-10s or your unit is out of " specs ". That never been happen in a unit of the DM-10 caliber, there is no reason for taht: something is " wrong " down there.

regards and enjoy the music,
R.
dover
2,243 posts
 
Henry - the Halcro inverts absolute phase in the phono only and not the line stage. Have you factored this into the equation. Also from time to time mains can flip in its phase orientation. Just be happy you dont live in Oamaru. My friends stereo sounds fantastic when the local abattoir ( meat processing plant ) goes on strike.
almarg's avatar
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almarg
9,670 posts
 
It confounds me as to how only the phono-stage can be affected whilst the AUX can sound as beautiful as ever at these times?
I don't see that as surprising. Unpredictable, yes. But surprising, no.

As you certainly realize, the phono stage uses circuitry that is not involved in the processing of Aux or other line-level signals. And that circuitry is vastly more sensitive, in terms of the signal levels it is designed to process, and provides far higher gain, than the line-level circuitry in the preamp.

Best regards,
-- Al
halcro's avatar
halcro OP
2,664 posts
 
Dear Nikola,
Battery powered phono stage?.........that sounds like a solution.
Finding one that will take balanced and unbalanced inputs together with balanced outputs and include variable loading and capacitance as well.....might be the problem?
Regards
halcro's avatar
halcro OP
2,664 posts
 
Hi Dover,
Yes.......I switched the phase switch during the occurrence.....but no change.
I'm currently Googling the location of abattoirs in my vicinity :-)
How about knackeries?
halcro's avatar
halcro OP
2,664 posts
 
Thanks Al,
As usual....you contribute some logical perspective.
How it gets past the Shindo power conditioner though.......is even more puzzling?.........and annoying!
Regards
Henry
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