Author Topic: Will this work?  (Read 2806 times)

JacoP

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Will this work?
« on: August 23, 2010, 01:52:11 PM »

I'm looking at connecting a Unity 1:1 Transformer between Phone Stage Out and Amp input.
I saw a unit at RS Components.

http://za.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6675950

Apparently this is good for DC Blocking and getting rid of Radio Frequency Interference.
I have a slight hum on my speakers when using my TT.




Offline Viagara

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Re: Will this work?
« Reply #1 on: August 23, 2010, 02:10:06 PM »
I have a slight hum on my speakers when using my TT.

It sounds like your TT is musically inclined ;D ;D ;D ;D ;D If you can hum it, I can play it - so I suppose if you can play it, I can hum it :D
Don't take life too seriously, you will not make it out alive.....

(Location Cape Town)
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JacoP

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Re: Will this work?
« Reply #2 on: August 23, 2010, 02:13:10 PM »
It sounds like your TT is musically inclined ;D ;D ;D ;D ;D If you can hum it, I can play it - so I suppose if you can play it, I can hum it :D

alphabet humor,

It's dry, but you can like it...  ;D ;D


Offline Viagara

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Re: Will this work?
« Reply #3 on: August 23, 2010, 02:14:59 PM »
He, he, he! Good one :D
Don't take life too seriously, you will not make it out alive.....

(Location Cape Town)
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Offline LAV

Re: Will this work?
« Reply #4 on: August 23, 2010, 02:18:02 PM »
 ;D

Jokes aside...I doubt that the hum you're experiencing is caused by the presence of DC or any RFI, in which case the transformer won't help. Is the hum not perhaps mains-induced?
Vaal Triangle (Southern Gauteng)

JacoP

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Re: Will this work?
« Reply #5 on: August 23, 2010, 02:22:00 PM »
;D

Jokes aside...I doubt that hum you're experiencing is caused by the presence of DC or any RFI, in which case the transformer won't help. Is the hum not perhaps mains-induced?

Hmmm... Good one.
By this you mean induced from the Amp or TT?
The CA Amp seems quiet on other sources, so maybe it is the ProJect TT I have. Maybe the drive motor or a bearing is causing this?


Offline LAV

Re: Will this work?
« Reply #6 on: August 23, 2010, 02:50:08 PM »
Hi Jaco

Might not even be from the amp or TT, it could be from other sources close by. At low signal levels (like the output of a TT) almost any mains-powered gadget in your house is potentially a source of 50 Hz hum.

Most audio-related hum problems are related to earthing, either a loose or missing earth connection somewhere or an earth loop.If it is an earth loop, your transformer idea might very will have merit, but I have no idea what the effect will be on proper matching between the TT and the amp input (We need some of the clevererer  ;) guys to help  :D)

If the audio hum is from the motor, it should stop when the motor is not running. Mechanical hum from the motor or bearing could possibly be transferred via the tonearm, but that's a different scenario altogether.

Can you connect the same TT to a different amp, and see if the hum is still there?
Vaal Triangle (Southern Gauteng)

Offline Viagara

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Re: Will this work?
« Reply #7 on: August 23, 2010, 02:58:41 PM »
This may be stating the obvious and seeing that my experience of Turntables is from a number of years ago, so forgive me if this is a silly assumption, but is the ground wire from the TT connected to earth? Or am I talking absolute hogwash? ::)
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JacoP

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Re: Will this work?
« Reply #8 on: August 23, 2010, 02:59:00 PM »
I will check tonight if a "noise" appears when I switch on the TT Motor.
If so, then I will have my culprit.


JacoP

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Re: Will this work?
« Reply #9 on: August 23, 2010, 03:01:07 PM »
This may be stating the obvious and seeing that my experience of Turntables is from a number of years ago, so forgive me if this is a silly assumption, but is the ground wire from the TT connected to earth? Or am I talking absolute hogwash? ::)

It's not that loud of a "hum".  ;)
I connected the TT ground to the Phonobox ground, but the Phonobox has no ground to the mains. Primarily because it uses an external DC Supply.


JacoP

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Re: Will this work?
« Reply #10 on: August 24, 2010, 07:09:36 AM »

Checked last night, and it is definitely the tonearm picking up something; I suspect a vibration from somewhere.

I only have the Amp and CDP on the same stand...



Offline Hi-Phibian

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Re: Will this work?
« Reply #11 on: August 24, 2010, 08:37:34 AM »
Phonobox uses an AC wallwart not DC, but that is not important.
Have you tried taking an additional earth lead from the phonobox earth post to the case of your amplifier?
Could the phonobox be near a magnetic field from another components transformer (amp or CDP for eg) or the turntable motor. try moving it around. Is the turntabble itself above a transformer of an amp for eg?
The project rpms all medite constuction offers no shielding for the cartridge, metal platters do for eg.
Bunch up the excess phono lead, keep it away from mains chords and transformers.

Good luck, hum busting is a bit trial and error but it should be possible eliminate.

Forget signal transformers. Good ones are not cheap and the higher a level they need to handle, the more they cost. They are themselves sensitive to hum pick up and anything that costs anywhere near the price of your phono stage is likely to have a negative effect on sonics.
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Fair, not crazy, cash paid for turntables and tonearms from Rega, Linn and Thorens.          http://www.croak.co.za

JacoP

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Re: Will this work?
« Reply #12 on: August 24, 2010, 08:51:16 AM »

Will try this, thanks, but I agree, it is difficult.
I also thought that the quite expensive QED Interconnects would have minimised effects, but ja....  ???
I was thinking of getting an Acrylic platter as well.


Offline Hi-Phibian

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Re: Will this work?
« Reply #13 on: August 24, 2010, 09:09:23 AM »
acryllic shields no better.. if this is the prblem, create more distance between the tt and the hum inducing component.
Proprietor of Croak Audio Exploration.
Fair, not crazy, cash paid for turntables and tonearms from Rega, Linn and Thorens.          http://www.croak.co.za

Online Steerpike

Re: Will this work?
« Reply #14 on: August 24, 2010, 02:25:49 PM »
Does the 'hum' get worse if you touch anything, like the pick-up arm? Or the pickup cartridge body?

Does it change as you move the pickup arm across the span of the record?

Coupling transformers certainly do work - IF the cause of hum is a ground loop. As said, good ones are costly. But if it's not a ground loop fault, the transformer won't fix it, and it will be an expensive waste.