[ratso]

anyone had any luck using the system recommended in the 'white papers' section of jensen transformers?
it seems like they have a more sensible and complete system for trying to kill hum then others. i have just ordered their test adapters (dummies) and an audio transformer seeing as how the company i ordered it from allows returns if it doesn't work. i will post after i recieve mine and tell you how it goes.

[craig223]

They work.  Got the hum out of my Direct TV satellite receiver.  Good Luck!

[pearsall001]

They didn't work for me. A $.99 cheater plug took care of the problem. That was some time ago, I've since swapped out a few things & the ground loop never reappeared.

[ctviggen]

I tried one and it didn't work.  What did work was changing phase at the breaker box for one sub and changing interconnects for two other subs. 

[Mightyburner]

Worked for me.  I had customer service on the phone as I pulled out and replaced every cable I had until I located the problem.

[richidoo]

The Jensen coax cable/FM antenna decoupler works very well for me. They recently changed this item to caps instead of transformer decoupling so it would work with satellite (or something like that). It is MUCH better build and sound quality than the unit I tried from Parts Express. I use the Jensen to kill the ground loop caused by the earthed shield RG6 antenna lead coming into the system. I am very impressed with the filter. But you gotta identify the loop first. Sometimes hum is not from a loop, but magnetic inductance (transformer coupling) which is a design compromise that can't be fixed with loop buster. Moving the transformer away from signal lines or shielding it from the circuit may help in that case.

A cheater plug is a good tool to hunt down the loop if mains related. But don't leave it in there, bust the loop and restore the safety ground. Good luck!!
Rich

[tdangelo]

I tried them when I had a ground loop problem with a pair of Jolida 3000's - didn't work and they veiled the sound, YMMV.

Tony

[PSP]

I placed a Jensen isolator between my CDP/DVD player and my preamp (the CD/DVD is connected to the TV, and the TV to cable and so I had  hum) and the Jensen very effectively eliminated the hum.  I did not notice any loss of transparency in my Orions. 

Also, I have twice (this is two out of two) found Jensen customer service to be outstanding (and so is their build quality).  IMO, Jensen is a top-notch outfit.

Peter

[Occam]

They didn't work for me. A $.99 cheater plug took care of the problem. That was some time ago, I've since swapped out a few things & the ground loop never reappeared.

One doesn't suggest such things in 'polite' society 
While disabling a mains safety ground on components which are supplied with grounded mains plugs, often can minimize ground loop hum/noise, it defeats a major safety precaution. If there is an internal fault inside the component that shorts potentially lethal voltages to the chassis, lifting the ground will prevent that voltage going to mains ground and tripping the mains breaker. With a 'lifted ground', that path is through you and/or your loved ones.

Components supplied with 2 prong plugs (other than AVA products, and possibly others) are certified by an ETL (government approved electrical testing laboratory) to take other steps, double insulation and minimal 'creepage' requirements, which provide alternative safety measures.

FWIW,
Paul

[Huck]

They didn't work for me. A $.99 cheater plug took care of the problem. That was some time ago, I've since swapped out a few things & the ground loop never reappeared.

One doesn't suggest such things in 'polite' society 
While disabling a mains safety ground on components which are supplied with grounded mains plugs, often can minimize ground loop hum/noise, it defeats a major safety precaution. If there is an internal fault inside the component that shorts potentially lethal voltages to the chassis, lifting the ground will prevent that voltage going to mains ground and tripping the mains breaker. With a 'lifted ground', that path is through you and/or your loved ones.

Components supplied with 2 prong plugs (other than AVA products, and possibly others) are certified by an ETL (government approved electrical testing laboratory) to take other steps, double insulation and minimal 'creepage' requirements, which provide alternative safety measures.

FWIW,
Paul

 Hi: These "cheater" plugs are illegal in Canada!! Go figure!  Huck

[art]

I tried them when I had a ground loop problem with a pair of Jolida 3000's - didn't work and they veiled the sound, YMMV.

Tony

The 1:1 Jensens are a bit rolled off in the top-end. The 4:1 ones are flat. Lundhal makes some 1:1 transformers that are flat, but have less out-of-band rejection.

Pat

[JimJ]

I like homebuilt tube amps, I'm going to make friends with high voltage sometime 

[Steve Eddy]

The 1:1 Jensens are a bit rolled off in the top-end.

Eh?

The 11P-1's -3dB is at nearly 100kHz. What are you calling "top end"?

se

[Speedskater]

AudioXpress magazine review of the Jensen ISO Max isolation transformer.
http://www.audioxpress.com/magsdirx/ax/addenda/media/hansen-galo2706.pdf

[NewBuyer]

I placed a Jensen isolator between my CDP/DVD player and my preamp (the CD/DVD is connected to the TV, and the TV to cable and so I had  hum) and the Jensen very effectively eliminated the hum.  I did not notice any loss of transparency in my Orions. 

Also, I have twice (this is two out of two) found Jensen customer service to be outstanding (and so is their build quality).  IMO, Jensen is a top-notch outfit.

Peter

I have used Jensen PC-2XR Pro-to-Consumer 4:1 transformers with great success as well, and no loss of transparency or roll-off of any kind was apparent. In fact, the sound quality was nicely improved, which I had attributed to both the ground isolation and the impedance benefit of the transformers.

Also found build quality to be outstanding as well as the customer service from Jensen. 

[art]

The 1:1 Jensens are a bit rolled off in the top-end.

Eh?

The 11P-1's -3dB is at nearly 100kHz. What are you calling "top end"?

se

Precisely. Which means it is going to be down a few tenths at 20 kHz.

Pat

[Steve Eddy]

Precisely. Which means it is going to be down a few tenths at 20 kHz.

Jensen specifies a worst case at 20kHz of -0.15dB.

Guess I'll start worrying about that soon as I manage to find some speakers that are flat to within 0.15dB out to 20kHz.

se

[Daryl]

Unbalanced equipment has no ability to reject ground differentials.

Therefore unbalanced equipment must be isolated to a high degree if any level of design quality/competency is present.

Very low primary/secondary capacitance in the power transformer and if the chassis is grounded then nothing can be connected to the chassis not the grounds of the RCA's and not the '-' outputs to the speakers.

Balanced equipment need not be isolated so long as a high level of common mode rejection ratio is achieved and common mode input impedance nice and high.

Power supply design and grounding schemes are fundamentals.

[bluesky]

Hi Guys

I thought I may add that Rod Elloitt has both useful information and some balanced PCB's available as a last resort option.  Doug Self's book also has a whole chapter devoted to this issue.  This information has sure helped me solve a couple of problems so please have a look.

I would strongly suggest to anyone not to use a cheater plug and take the time to work through their hum issue.

Being electrocuted can ruin your whole day!  I try to keep it in perspective, death or hum, hmmmm......now which one would I choose.

Bluesky

[art]

Precisely. Which means it is going to be down a few tenths at 20 kHz.

Jensen specifies a worst case at 20kHz of -0.15dB.

Guess I'll start worrying about that soon as I manage to find some speakers that are flat to within 0.15dB out to 20kHz.

se

And your point is??????

My point is:

I tried them when I had a ground loop problem with a pair of Jolida 3000's - didn't work and they veiled the sound, YMMV.

Tony

Seems that someone can hear that 0.15 dB. Actually, I am sure that 99.99% of the people here can.

Pat