MGhead DT/OTL
Aug 14, 2002 at 1:40 AM Thread Starter Post #1 of 21

Sovkiller

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I got an MGHead amp, and when I hook it directly to the CD player, it works perfect, but when I hook it on a preamp OUT, (as I want to use the equalizer that I have installed in the system, and I have an extra line out) I hear a noticeable hum in the background, (if I unplugged the wires even with the wires in my hand the noise disapears), another thing is that the volume decreases about 50%, is that normal, what am I doing wrong? Cause usually I didn't heard any noise through my regular speakers, or even another headphone amp (solid state) that I have, Could anybody offer me a solution in order to use the EQ with the amp, or any other solution or headphone EQ? I can't hear the music tortilla flat, as the output of a CD player, I was trying for a long time but I think is a bad habit that I got used to.....I have a pair of Seenheiser HD600 and a Sony MDR-7509, both sound pretty good for me....
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Aug 14, 2002 at 4:10 AM Post #2 of 21

fredpb

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Sorry about your ground loop problem. Make sure all components are plugged into the same wall outlet. Try using the MG Head with preamp out without the equalizer. Try the equalizer between the cd player and the MG Head. Perhaps one of the components is causing the ground loop.

From left field......could be a bad cable, though I doubt that.
 
Aug 14, 2002 at 4:25 AM Post #3 of 21

Sovkiller

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I have a dedicated power supply for them, with filters and a UPS, all is connected through directional interconnects, AR gold plated, and as I explain there I never had this problem before with any of my equipment, all is connected the same way, the EQ does not make that noise, I think is something between the preamp and the MGHead, as every time I hook it to the preamp the hum appears, but what to check with the preamp, is not defective, a missing ground? I plugged it in differents outelet of the power supply and is still the same...I'm desperate with this I spent some money in vane I think...
 
Aug 14, 2002 at 11:49 AM Post #4 of 21

Nick Dangerous

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Sounds like a ground loop to me.

Try this: connect an alligator clip wire from the chassis of the preamp to somewhere on the front plate of the MG Head.

Any difference?

Also try connecting it from the chassis of the MG Head to other components/locations. Sooner or later you'll break that loop or go insane trying.

It's a trial and error process.
 
Aug 14, 2002 at 1:27 PM Post #6 of 21

Hirsch

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If you think you've got a ground loop, try using a "cheater plug". This takes a three prong AC cord and reduce it to two plugs. If using the two prong plug works, you've found your problem.
 
Aug 14, 2002 at 2:57 PM Post #7 of 21

Sovkiller

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I already got crazy with that, I have a Pre One/A made by Audiosource, it doesn't have any ground connector, but I was trying in all the chasis, I will do it again but, I do not think is the solution, so please, please!!! any other suggestion, please...what about the "cheat prong" that someone suggested, I'm at work now, as soon as I reach home I will try it...please HELP!!!!!
 
Aug 14, 2002 at 5:12 PM Post #8 of 21

braillediver

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Are you hooking up the MG Head to the Pre-Amp out or to a line level out like a recording output? Just a thought.
I hooked up my MG Head last night for the first time and it is comepletely quiet. Slow methodical steps are needed to isolate the problem. Patience helps. It'll probably be something simple in the long run.

The cheater plug will just remove the earth ground from that component thereby removeing that path for the ground loop.

Just keep trying things till it works I was blown away last night by the sound I heard, it was awesome and that was with stock tubes and not burned in.
 
Aug 14, 2002 at 5:21 PM Post #9 of 21

Sovkiller

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I just get a set of aligators from Radio Shack to see if is the ground of any component, I hope to fix that, I will try the cheater also to see if that works, but as I explain before the amplifier without any source is completelly quiet, if hooked it to a cd player alone or the EQ alone, it is also quiet, the problem is something related to the connection between them, so is not the amplifier ground what is wrong, has to be the pre. I will keep on working on that as soon as I reached home, if I od not become crazy before!!!!
 
Aug 14, 2002 at 6:02 PM Post #10 of 21

john_jcb

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Quote:

Originally posted by andrzejpw
So what's the fix for this?
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Or are all MG heads like this?


If it is a ground loop problem it is not the equipments fault but differences in the ground potential. The link below contains a one page description of the problem and solutions.
 
Aug 14, 2002 at 6:41 PM Post #11 of 21

Sovkiller

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John the link is missing, cna you post it again please?
 
Aug 14, 2002 at 8:32 PM Post #13 of 21

Sovkiller

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Jesus!!! the magic comes back!!! Thanks very much for the advices, and the help, you make another headphone lover happy, just the cheater plug and it works like magic!!!! with people like you...wow!!! I owe you a six pack and a CD of Mike Stern here at home, through my Sennheiser's HD600, in the quiet of the night looking to the night view of NYC, is a total eargasm, Jesus!!! So Hirsch and John, I owe you a six pack......

Hey Nick!!! don't feel bad for that, I got something for you too, I just rolled the tubes as you suggested, a couple of JJ and a GE 5751, sorry I couldn't find the beloved Sylvania's, what else to ask for here, is day and night of the stock tubes, and the difference in gain is not so noticeable, as the sound improvement, I will return the aligators for now to Radio Shack and end of the story I'm very pleased with the sound maybe in the future, I'm not going to play with that, specially when I have a big A/V furniture that has to be move and is a whole hassle, just the plug for now....
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Aug 15, 2002 at 12:04 AM Post #14 of 21

Nick Dangerous

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Glad you found the problem! Banishing hum can be tricky sometimes. I float the ground on my Paraglow amps for best performance... but depending upon the component arrangement upstream it is occasionally better to ground them directly. Gotta keep experimenting!

Hirsch does rule, by the way.
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Aug 15, 2002 at 12:40 AM Post #15 of 21

Sovkiller

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By the way Nick where can I get a Sylvania 5751 or a Mullard or a Raytheon, or the Arcturus, the GE I got was the regular grey micas, JAN everybody sells, do you have any "secret link" for these rare tubes?
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