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Topic: Feedback Loop TV/Cab Stereo/Generator (Read 336 times) previous topic - next topic
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Feedback Loop TV/Cab Stereo/Generator
Hi folks,

Previously on..."The Generation Gap"...

The discussion began with power inverters being unable to run an espresso machine and the desire to satisfy the DW and her need for her morning espresso.

The discussion moved forward (very quickly) to generator maintenance and somehow melded into the need to feed the LD TV audio to the cab stereo.

All was well...until...da, da, daaaaa! The dreaded Feedback Loop. You know, that horrifying hum that becomes oh so apparent when you've made a bad audio connection.

Recently, I was exercising the generator and decided to watch a movie and patch the TV audio output to the cab stereo like I have done in the past. What the...?

Apparently the generator casts a powerful curse upon any attempt to do such. This is also true when connecting to a Bluetooth speaker while it is being charged via 110 and the genny is running. Ouch! What a racket.

The solution? Don't do that! Keep your Bluetooth Speakers charged and get your audio that way. Or use the puny TV's built in speaker. Or...read a book.

Just an FYI.

Kent
2015 27' RB "MissB.Haven"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #1 –
Forgive an old technician's nitpicking, but from your description, that's not actually a feedback loop--it's 60 Hz AC hum. Feedback manifests as a high-pitched squeal when a microphone and amplified speaker are in close proximity. (It often happens in public venues with PA systems, or when people are putting in or taking out hearing aids.) AC hum is a low-pitched buzz or hum at sixty cycles per second--the standard US power frequency.

AC hum can be tough to get rid of, even when plugged into shore power. In your situation, it's exacerbated by the fact that the Onan generators put out fairly "dirty" AC power, rather than a nice clean sine wave, and the factory-installed converter lets some of that nastiness through into its 12 VDC output. I've had similar problems with 12 V-powered computer speakers in my rigs.

The easiest answer, as you pointed out, is to use battery-powered speakers. Even when charging, they generally won't hum or buzz. That's been my solution.

Andy
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #2 –

There are a lot of potential causes of hum.
Many times a pair of ground loop isolation filters cures the problem.
Used to buy them are Radio Shack.
Here is another version.
Amazon.com: Absolute PNF200 Power Noise Filter/Ground Loop Isolator: Car...

Larry

As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #3 –
Andy,

Thanks for the clarification. Still comes down to the obvious though...don't do that.

TV to Cab Stereo works perfectly well as long as the genny is taken out of the equation.

Kent
2015 27' RB "MissB.Haven"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #4 –
Kent,
Love your member Picture!  Is that Mom's favorite?

With the old M & B  Magnnatec 6336 converters the Television outlets, CB, and well Refrigerator are all hooked to the battery to filter the rectified 12 VDC ripple and handle the 27 amp refer heater.  They have a lighting load half and a trickle charging half and a NC relay that opens when the 120 VAC is connected.

I remembered the hard way, when i turned on the CB with the coach plugged in and the battery disconnected. What wrong with this New CB?  HA HA!

Rodney
'88 MB
Rodney
1988 Mid Bath
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #5 –
...& I thought "feedback" was when I was hearing myself "echoing" in the phone (every phone in the house) as I talked with someone   :P  --(like when they tell people on radio call-in shows to turn off the radio).  Went on for a couple of days & I thought it might be the router, since I have the Walmart StraightTalk Home Phone (which I've been told is on the Verizon network through a reseller)...then it magically disappeared as mysteriously as it had started--grrrr...arrgh with apologies to Mr. Jinx (the cartoon cat of days gone by) "I hate meeces (& gremlins) to pieces". 

Lynne
Lynne
LDy Lulubelle, Green '05 31' TB
Lilly, the 4-Legged Alarm
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #6 –
Quote from: rodneyhelfrich  - 

"...Kent,
Love your member Picture!  Is that Mom's favorite...

...I remembered the hard way, when i turned on the CB with the coach plugged in and the battery disconnected. What wrong with this New CB?  HA HA..."


Rodney,

It's amazing how quickly we find "the wrong way" to do something. Could make an interesting thread topic.

My Avatar was sent to me via my brothers family archive. Not sure how old I was but it looks like 7th grade Glee Club.

Not sure if Mom even remembered the pic existed. I'll have to ask her in my dreams as that's the only way I get to see my folks anymore. Now that's an interesting "loop" to find yourself in.

Hey it's all good right? Except that nasty hum. Like Dobbie Gillis said to Zelda Gilroy, "Now cut that out"!

https://youtu.be/Be0eTnCd_1g

Kent
2015 27' RB "MissB.Haven"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #7 –
Quote from: Kent Heckethorn  - 
All was well...until...da, da, daaaaa! The dreaded Feedback Loop. You know, that horrifying hum that becomes oh so apparent when you've made a bad audio connection.

Larry's answer hits the mark dead-on. This is a ground loop, not really feedback, and is typically a hum. What is worse, it can be a sign that serious damage is about to occur. It is caused when the audio/video signal ground is not at the same electrical potential at both ends of the connecting cable. This rarely happens in home media equipment, but is particularly an issue when such equipment is run from a 12Vdc source via a 120Vac remote power brick that is eliminated for direct 12V connection in the rig. Often the audio/video ground in such equipment is NOT the same as the power input negative connection. When connected to equipment - such as the dash radio - that DOES use the vehicle ground for the jack ground, DC current will flow, potentially damaging either or both pieces of equipment. The isolators Larry mentioned eliminate the issue.

Steve
2004 FL
2013 Honda Fit
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #8 –
"I thought 'feedback' was when I was hearing myself 'echoing' in the phone (every phone in the house) as I talked with someone..."

You're right--that actually is feedback... but delayed by network transmission time and/or analong-digital conversions in the phone system. Depending upon the connection, the delay can vary from imperceptible to a second or more, which is very distracting.

..."like when they tell people on radio call-in shows to turn off the radio"

That's delayed feedback too, but a different situation with a different cause. Talk shows introduce deliberate "broadcast delays": all the audio is delayed (typically by 30 seconds), giving engineers time to censor any off-color remarks made by callers.

Yeah, I know--more than you needed to know. Just couldn't resist. :-)
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #9 –
"...more than you needed to know."

Oh, I could have told you that! Could have is the key here because that would have been 20 or more years ago when I still had memory banks that worked. Since then I've let those bits of knowledge escape into the nether world, along with what I once knew about vacuum tubes and image orthicon TVs.   ;)  :'(
Steve S.
Lazy Bones & Cedar
2004 30'IB (Island Bed)
Yesterday is History, Tomorrow is a Mystery
Live for the day!
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #10 –
Andy said, "Yeah, I know--more than you needed to know. Just couldn't resist. :-)"

But I like those tidbits--as I've said before, just reading these discussions makes me feel smarter, even if I don't always know where I've been or am...or how I got there.  ;D

In a previous life, when Trivial Pursuit first came out, we were having a rather raucous game when a question about poetry came to my kids' dad.  The man had a degree in Ag Econ from Mizzou, but had reached a point where his most intellectual discussions occurred with the sows in the farrowing house...but somewhere in the depths of his gray matter came "It sounds like Keats to me."  No one was more surprised than he when that turned out to be the correct answer.   ;D  

So I just kind of soak up all sorts of info & am likewise surprised when those tidbits float to the surface of my own gray matter.   ;D   Thx, Andy.

Lynne
Lynne
LDy Lulubelle, Green '05 31' TB
Lilly, the 4-Legged Alarm
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #11 –
Electrons.  I really hate electrons.  Give me good oil lubricated parts and it would all make sense.

HD
2014 27 MB
Towd: Either the Jeep Wrangler or trailer containing the BMW R1200GS and 2 E-bicycles
Happy wife=Happy life
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #12 –
HD said,  "Electrons.  I really hate electrons.  Give me good oil lubricated parts and it would all make sense."

I'm not a motorcycle person, but saw a really interesting dramatization about the early days of Harley-Davidson the other night as I was surfing (I think on Discovery).  It amazed me what people created from nothing but what seemed like baling wire & bubble gum (being facetious there). Truly, the fact that they had to make the machines to make the parts for their machines reminded me that we truly are/always have been a great nation (in spite of our human failings).  I salute all of you who "make sense" of both "Electrons [&] good oil lubricated parts..." & thx for taking some of the rest of us along on the ride. ;D

Lynne
Lynne
LDy Lulubelle, Green '05 31' TB
Lilly, the 4-Legged Alarm
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #13 –
Quote from: Lynne Broyles-Greenwood  - 
HD said,  "Electrons.  I really hate electrons.  Give me good oil lubricated parts and it would all make sense."

I'm not a motorcycle person, but saw a really interesting dramatization about the early days of Harley-Davidson the other night as I was surfing (I think on Discovery).  It amazed me what people created from nothing but what seemed like baling wire & bubble gum (being facetious there). Truly, the fact that they had to make the machines to make the parts for their machines reminded me that we truly are/always have been a great nation (in spite of our human failings).  I salute all of you who "make sense" of both "Electrons [&] good oil lubricated parts..." & thx for taking some of the rest of us along on the ride. ;D
Lynne

And it continues today! One only has to look at what ingenious things Tesla is doing to develop the electric car and sustainable energy for the masses. They just bought out a German engineering firm that makes the machines that makes the cars.

Tesla acquires German engineering firm to create ‘Tesla Advanced Automation...

Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #14 –
Hey! Where are we going with all this? Wherever it is I'm climbing aboard.

Some threads are meant to wander abroad and take us for a ride on the "train of thought".

The concept of electric cars intrigues me. But for kicks, if I get one, I'm putting in a 1000 watt sound system that sounds like a good Ol' fashioned V8 roaring down the road. Watch out Tesla I'm coming through!

Ho, Ho, Ho!

Kent

2015 27' RB "MissB.Haven"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #15 –
Quote from: Lynne Broyles-Greenwood  - 
Andy said, "Yeah, I know--more than you needed to know. Just couldn't resist. :-)"

But I like those tidbits--as I've said before, just reading these discussions makes me feel smarter, even if I don't always know where I've been or am...or how I got there.  ;D

The core purpose of this site is to pass along information, primarily on LDs and RVing. This can include a wide range of subjects.
There a several among us, self included, who tend to get deeper into subjects than what many immediately understand.
Education is about being exposed to things you previously didn't know about. Those who want to learn more can then research the subject on their own or ask questions here.  Any excessive information can be immediately forgotten.
There have been many topics, on the site, that have caught my interest, leading to hours of researching and learning about a new subject, often from  an "more than you needed to know" posting. Education is a life long occupation.

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #16 –
Agreed 100%. The beauty of any discussion is that it often opens the door to knowledge and long forgotten memories.

Sometimes one may simply gloss over a thread and then find a tid-bit that strikes their interest.

All good...now what were we talking about?

Kent
2015 27' RB "MissB.Haven"
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #17 –
Quote from: Kent Heckethorn  - 
The concept of electric cars intrigues me. But for kicks, if I get one, I'm putting in a 1000 watt sound system that sounds like a good Ol' fashioned V8 roaring down the road. Watch out Tesla I'm coming through!

I was reminded that electric cars are not a new idea when we were at the Smithsonian a couple of years ago.



Art
Art and Barbara
Settled in Atterdag Village of Solvang
2015-2022 fulltime in a 2016 Tiffin Allegro Bus 37AP
2002-2015 2002 LD MB
Art's blog
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #18 –
Quote from: Older_Fossil  - 
I was reminded that electric cars are not a new idea when we were at the Smithsonian a couple of years ago.
Jay Leno owns one.
https://www.youtube.com/watch?v=CRwEXaHTwsY

Years ago,  we saw a local PBS program that had Huel Howser, visit the Nethercut Museum, in Sylmar,  and drive the same electric car on the streets. It was a very civilized car for the times, primarily made for women, who would not or could not hand start the cars of the time.
Vintage Electric Cars-California’s Green (127)

The lack of range and the cost of charging eventually killed this car.
Lack of range is the same issue today that keeps electrics cars sales low  (only about .6% of the cars sold in the US today are electric)...no matter how many Teslas you might see. They are a status symbol in California.

FYI, Huel Howser was a long time Public Television show host (KCET) of a several California-only travel and interview shows. His shows sent us out on the road many times, to see the newest treasures he had discovered.
His shows still are still in reruns today, several years after his death. If interested, his shows are available online, from the Chapman University archives.
| Huell Howser Archives at Chapman University

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
 
Re: Feedback Loop TV/Cab Stereo/Generator
Reply #19 –
If interested in electric cars, you may want to check out the documentary "Revenge of the Electric Car." It's very informative, albeit somewhat dated since it was released in 2011. I think it might still be available for streaming on Netflix.

Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264