Emotiva DC Blocker (Hook up)

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Mark Korda

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Emotiva DC Blocker (Hook up)
« on: 5 May 2021, 02:17 pm »
Hi, I probably sound like an idiot but I have a few questions I think you guys I bet know.
     I have an Emotiva DC Blocker CMX 2. There are 2 outlets on this devise. It's in my bedroom system which consists of a Onkyo C-7030 cd player, a preamp, and a Dynaco ST-70 that has worked flawlessly but like the preamp,and I'm talking a few different ones,has an older 2 prong plug. I needed an extra outlet so I plugged a 6 plugged power strip into 1 outlet on the Enotiva which is then plugged into the wall. My fuse box has a breaker for just that one room. I have a dimmer switch also but tried it in and out of the circuit before and did not notice any difference.
    I can hear the transformer buzzing when I get close to my system. Here is another thing; I thought my Onkyo cd player was making a small hum noise too. I spread my fingers like attempting to palm a basketball and pressed down on the Onkyo's chassis and that slight downward pressure makes a big improvement in reducing the hum. Is my body acting like a ground? I have used passive preamps with  no power cords and still get a slight hum, the same as with a 2 prong plugged preamp,Dyna PAS. The hum never comes from any of the preamps but the cd and power amp. Any ideas?...thanks so much, sincerely Mark Korda

eichlerera1

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Re: Emotiva DC Blocker (Hook up)
« Reply #1 on: 5 May 2021, 02:26 pm »
Do any of your pieces of equipment use toroid transformers?
As cited many times, they are prone to hum due to DC Offset.

I suggest you mass load ALL of your gear, using heavy lead weights.

Mark Korda

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Re: Emotiva DC Blocker (Hook up)
« Reply #2 on: 5 May 2021, 03:36 pm »

     Hi Eichlerea1, I already did that. That small York dumbell plate,cast iron, has the same effect as I mentioned wnen I put hand pressure on my cd chassis. It is located over the Dyna's power transformer and brings the hum down a little bit.Could this be because of the weight, ground or induction? There's no toroidal transformer in the Dyna.The cd player? I'll have o look.....Mark

Speedskater

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Re: Emotiva DC Blocker (Hook up)
« Reply #3 on: 5 May 2021, 07:11 pm »
Hum/buzz coming out of the speakers is one problem.
Mechanical hum/buzz of a component is a very different problem.

rollo

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Re: Emotiva DC Blocker (Hook up)
« Reply #4 on: 5 May 2021, 08:07 pm »
Hum/buzz coming out of the speakers is one problem.
Mechanical hum/buzz of a component is a very different problem.


  How can one tell the difference ?? Thanks.


charles

NoDisco

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Re: Emotiva DC Blocker (Hook up)
« Reply #5 on: 5 May 2021, 11:12 pm »
You can’t. In my case them hum transfers over the entire signal chain. I have tube pre that is nicely detailed, but it only plays well with certain amps. If I use it with tubed monos, the hum at the pre amp power transformer is pronounced. It passes it to the monos, and then the speakers. It hums less with with a tubed integrated I use and even less with solid state. I’d say it’s a grounding issue, but all the connections are the same (ICs power cords and power outlets). I’m anxious to try a humdinger, but my WA22 pre/headphone amp REALLY gets along with my old NAD 372s power section. I have high current SS monos, and I am going to try those later this summer. When the fall comes and I go back to all tubes I will likely get a humdinger.

Mark Korda

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Re: Emotiva DC Blocker (Hook up)
« Reply #6 on: 7 May 2021, 03:17 am »
Hi No Disco, I noticed the same thing you said as I could hear the humming close range on my amp, cd player,and speakers. One thing I noticed on 99 percent of Dynaco tube amps was the lack of screws securing the transformer bells to the transformer it's self. I wondered if age on the plates in the tranny might introduce vibration as they rusted so minutely. I put a wooden carpenters shim under my power transformer.I think you can see the screw holes where there should of been some bolts securing the bells (outer casings). The wood shim did reduce some some hum. It's kind of like what a wooden axe handle does by absorbing vibration. One more thing; I took my cd player back to where I bought it so the Hi-fi guy could hear it and it was dead silent,I was there with him. Take care No Disco....Mark Korda


Mark Korda

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Re: Emotiva DC Blocker (Hook up)
« Reply #7 on: 7 May 2021, 01:49 pm »
Hi, here's 2 more observations I have.I saw a You Tube video on building McIntosh transformers.They showed filling the bell housings with some sort of hot tar.Would this be to minimize vibration because of the iron plates oxidizing? Also on EBay someone sells a box to bring down your voltage to the day the ST-70 was invented.Is today's voltage from your wall cause your transformers to hum because it's higher today? Thanks a lot....Mark Korda

rollo

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Re: Emotiva DC Blocker (Hook up)
« Reply #8 on: 7 May 2021, 07:10 pm »
Hi, here's 2 more observations I have.I saw a You Tube video on building McIntosh transformers.They showed filling the bell housings with some sort of hot tar.Would this be to minimize vibration because of the iron plates oxidizing? Also on EBay someone sells a box to bring down your voltage to the day the ST-70 was invented.Is today's voltage from your wall cause your transformers to hum because it's higher today? Thanks a lot....Mark Korda


 Yes it is dampening material.



charles

Speedskater

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Re: Emotiva DC Blocker (Hook up)
« Reply #9 on: 13 May 2021, 05:07 pm »
  How can one tell the difference ?? Thanks.
charles
Put your ear near the component. is it buzzing?
Put your ear near the speaker. is it humming?
* * * * * * *
Buzzing can sometimes be reduced by tightening the transformer's mounting hardware. (AC cord unplugged !)
Or by dampening material between the transformer and the component's cover plate.
* * * * * *
If it's speaker hum.
Power off, remove interconnects from amp input, power on. Does the speaker still hum?

avahifi

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Re: Emotiva DC Blocker (Hook up)
« Reply #10 on: 13 May 2021, 05:40 pm »
The metal chassis top on the ST-70 acts as a big sounding board, amplifying mechanical hum from the attached ST-70 power transformer.  The hum itself can come from low level DC on the power line or just loose internal plates in the transformer. Generally this hum is not transferred to the speakers.

Hum from the speakers comes from grounding issues, or because the system does not know the words.

No cure for loose plates other replacing the transformer.  Low level DC is blocked by our HumDinger and that might help you.  People tell us it works better then the old Emotiva unit.

Frank