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mono block ground Loop?

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Posted on December 26, 2016 at 13:00:43
walkstoslow
Audiophile

Posts: 277
Joined: November 18, 2012
 hello Inmates
My previous post titled to "buy or build" is done.
This was a project consisting of two mono phone plugs, one from each mono amp to a stereo jack.
Being mono I ended up connecting the ground of each amp together at the stereo jack.
Have I introduced to myself a ground Loop?
Seems now that I should run a mono line to each side of the headphones
rather than use a stereo jack.
I suppose the ultimate ideal is to never arrive....
Opinions?
Tia

 

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RE: mono block ground Loop?, posted on December 28, 2016 at 16:34:00
Bill Way
Audiophile

Posts: 1884
Location: Toms River NJ
Joined: May 28, 2012
Contributor
  Since: December 14, 2012
 Are you getting hum?
"Put on your high heeled sneakers. Baby, we''re goin'' out tonight.

 

RE: mono block ground Loop?, posted on December 29, 2016 at 12:03:49
walkstoslow
Audiophile

Posts: 277
Joined: November 18, 2012
 Bill:
I am not getting hum, though I am getting distortion in one amp after the above mentioned wiring, A-B'd the Integratated mono-blocks, definitely not the same output now.
I bought these heathkit amps (AA-18) as a mono project , as the plot now thickens, now that I have two.
I hope it is not the transistors.
All I wanted are two identical mono amps, sounding the same.
I am a vintage nut, not being a trained tech is killing me.
I worked at a TV shop during High School, 47 years ago, I should have stuck with it or perhaps paid more attention.
Now I am listening to a Sony PS1 into a AA-18, thru a optimus pro LX5
with the Linaeum tweeter. a set of Kenwood KH-51 (football) headphones Not much money invested all of this.
Thanks in advance for suggestions.

 

A few comments, posted on January 12, 2017 at 05:24:22
Frihed89
Audiophile

Posts: 15703
Location: Copenhagen
Joined: March 21, 2005
 I am pretty much flying blind, here.

If you are trying to connect headphones to the monos speaker jacks, the hum may be coming from the amplifiers and not a ground loop and/or aggravated by high gain in your system and sensitive headphones. If so, this can be solved to some degree by a resistive headphone adaptor (attenuator), connected to the speaker outputs of the amp(s) and/or different headphones.

Are you sure that the rca connectors in your system are properly grounded and have good solder joints.

A fair amount of the time, ground loops come from having different components attached to different AC outlets, a problem solved by a mains distributor that has enough sockets to connect all of your equipment.

Are the grounds you connected extra?

 

amp hum, posted on January 13, 2017 at 12:52:36
walkstoslow
Audiophile

Posts: 277
Joined: November 18, 2012
 Hello:
yes, you are correct, the hum is coming from both amplifiers.
I went back to mono mode and listened to each one individually.
These SS amps are old, made in 67 or 68, I believe.
I also just acquired the same amp in kit form.(Heathkit AA 18).
I also got The Heathkit "Electronics Essentials, along with the companion workbook, a course for techs in wanting.
I would like to end up with a trio of identical amps.
First I need to understand where exactly the hum is coming from.
Hence the text books. I have dabbled off and on for many years.
I am thinking the power caps first, to be replaced, and then the coupling caps.
After that it is wide open as what to do next.
Question: This NOS kit that I just acquired, should I plan on replacing the caps now because of the age of this kit?
Hopefully building this amp will help me understand how these things work.
All suggestions and comments are appreciated.
thanks

 

RE: mono block ground Loop?, posted on January 13, 2017 at 12:54:16
walkstoslow
Audiophile

Posts: 277
Joined: November 18, 2012
 see above

 

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