Isolation Transformers for 1068 Connection

[chanlon]

Hello,

As I mentioned in a previous posting
(http://www.htguide.com/forum/showthread.php4?t=142)
I've been dealing with an extensive ground loop problem that is caused by a 5.1 analog connection and component video connection between my 1068 and Sony SACD/DVD player. Remove either connection, and the humming disappears. I've tried different SACD players but the humming is still there.
However, when I tried a different processor, the humming dissapears

Rotel has told my dealer that they have no history of this problem. Rotel's technical supports suggests," I would suggest using
isolation transformers between either the 5.1-analog input, or the
component video. This isolation transformer will eliminate any physical
connection but will connect electrically. "

I'm hesitant to do this since it seems like a band-aid approach. Plus, I can't seem to source a ground loop isolator that consists of a quality RCA cable.
They are all made of cheap cables. Thus, it only degrades the quality of the signal.

Any suggestions of where I can purchase a "good" isolation transformer?
Or, do you believe that its the fault of the processor and I should be a little more assertive with Rotel?

Thanks in advance

[Kevin D]

I highly recommend the Jensen line of isolations transformers. You can use the component video one, but would need an additional component video cable. It's around $500 retail, but maybe your dealer would be willing to sell it at cost to help you out.

http://www.jensentransformers.com/index.html

Kevin D.

[chanlon]

Thanks for the link Kevin. Any opinion on the processor itself?
Do you see the benefit it getting Rotel to look at the unit?

[Club1820]

Wow! $500! I think I would rather replace that 1068 or dvd player if I need to spend that much to get rid of a ground loop. IMO.

[Kevin D]

Thanks for the link Kevin. Any opinion on the processor itself?
Do you see the benefit it getting Rotel to look at the unit?

It's certainly an odd problem. I believe you've tried a different 1068 and different DVD. The only way for them to figure it out is to have the processor and DVD there in house. I would make sure the loop is present in other house's / the store, you never know what the power in your house could be doing.

Kevin D.

[chanlon]

Yes, I tried a different processor and it fixed the issue.
Its obvious that its an issue with the processor.

I don't want to spend more $$$ so I will be sending it back to Rotel for service. I'm starting to lose my patience.

Thanks for your posts and help on this matter.

[Club1820]

Chanlon, can you update us on your 1068 ground loop problem?

I'm having the same issue with my 1068 & the Cable TV connection.

Thanks.

[nyny]

Hi guys,

I am having ground loop issue with my RSP-1068 and CATV as well. Just ordered VRD-1FF from Jensen Transformer; hopefully this will solve the problem. I will provide my update after I receive the unit.

Cheers,
Tony

[nvdeynde]

Hi,

The ground loop is introduced before the Rotel Processor is earthed and most likely the rest of your equipment is not or perhaps your SACD player is earthed and the Processor not.

Depends on the power socket. I own the European version of the Rotel Processor and this one is earthed.

Now you get a ground loop when you have different grounds:

Example: ground from your electrical wiring and ground from the TV / Tuner or Sattellite receiver.

Cheapest solution is the cheater plug that basically isolate your equipment from the ground of the power mains.

Safest and solution for most cases are the Yensen VRD-1FF CATV isolators that you place between the connection of you cable TV / SAT / Tuner. You need 1 for each cable.

With the CATV isolators, you isolate the ground from the cable TV/SAT and you won't have the problem anymore.

A simple test: unplug the arial connection cables of your tuner/TV/SAT and the hum / ground loop should be gone.

Remember when that all your equipment is connected together and the ground is common for all your equipment through the ground of the phono connectors or scart cable, whether it are the component photo connectors or audio one's: doens't matter, they transfer the common ground from one piece of your equipment to another.

Nico

[Club1820]

yes, the "major" hum is in fact caused by my cable connection. confirmed as you say - by disconnecting the cable from the wall.

after this, there still exists a small hum that is noticeable when the volume is low - usually when watching tv at night. Still annoying.

Will there always be a hum - even a slight one? I guess I am just going to have to reconnect every unit in the system one by one to determine the cause. This actually is how I figured out the Cable TV hum. It just so happened it was the first thing I tried.

If at this point this is the best I can do/expect, then I guess I will live with it. Still annoying though!

Plus - Last night I realized my 1068 hums also - even with everything powered off. Only noticeable when I put my ear close to it.

Oh well. 8O

[nvdeynde]

Hi,

I don't know what your end-amplifier is but there will always be some "ground level" hum.

The ground lebel hum is the hum you hear all the time with volume turned to zero.

The end-amplifiers will produce a bit of hum, particularly audible through the tweeters and a bit through the mid-range speaker. The more power your amplifiers has, the more audible this ground level hum will be.

This is unavoidable.
You can invest into very expensive conditioners like the 300/600 series from PS Audio which will reduce the ground level a bit or a lot depending on your setup but then again you have to ask yourself the question: Do you want to buy a power conditioner that costs 1 to 3 times the price of your DSP processor...

So a bit of hum at very silent levels is normal. Loud hum is not: then you have a ground loop problem like I described earlier today.

As for the internal transformers of amps and pre-amps/DSP's: every transformer makes an audible buzz when you put your ear against the case.
This is also normal. If you can't hear it 1 meter away or 3 foot then everything is normal.

What I can't say from my own amplifier but that's another topic 8O

As for the Jensen CATV ground loop isolators: you can fix your whole setup by using just 1 isolator is you can place it before the junktion box of the cable company as their splitters splits the signal into TV and FM ( at least here in Europe ).

If you have TV/FM and a sattellite dish as well: you need to put a CATV isolator between your sattelite coax cable and the one from TV/FM over the cable.

Here in Belgium sattelite reception is rare: we get our TV and radio channels through Coax cable from the Cable Company.

The Yenssen isolators are greath but in my opinion you only need one piece so for about 50$ your problem should be solved.

I don't believe the Rotel DSP has anything to do with the problem. Any other electrical earthed component will give you the same problem if you have another ground from Cable TV/FM or Sattellite.

It can be a 1 of a kind problem with a defective Rotel 1066 that has a faulty input for the 5.1 analog connection but that will be rare. Unplug your TV/FM/SAT leads and if it still humms then: it's the Rotel 1066 that's defective.


Take Care,

Nico

[voxy]

Does such hum also appear in ICEpower amps?

[nvdeynde]

Hi,

Every component of your hifi-system that's connected to your amplifier induces additional ground floor noise over the analog audio/video connections.

How much depends on the quality of the component.
You can also of course use the digital optical connections only and not connecting any analog phono jacks: then the ground level floor noise is determined by you pre and end-amp only but then you won't be able to listen to DVD-audio for example..

Even the best amplifier, integrated or separate pre- and end amplifers, will have some ground floor noise, even the digital one's ( at least those I've heard ).
I have heard the best amplifier from B&O ( a digital one ), superb sound, but not 100% noise free. You still could hear the ground noise with your ear against the tweeters but it was very...very low, almost perfect.


Nico

[chanlon]

My 1068 is currently gone back to Rotel for repairs pertaining to this ground loop issue. Apparently its an issue with an early production run of these processors that can be fixed by a Rotel modification at the factory.
Apparently this condition exisits or shows itself only in rare circumstances. Mine using a SACD player with an analog 5.1 connection combined with a component video cable connection from the same player.

Its clearly a problem with the processor since I've tried different processors and SACD players in my setup. You should note that I'm not talking about a barely audible humming sound here. Its a very noticable humming sound that even my wife complained about.

Let me know if you have any other questions.

[Club1820]

Chanlon, please keep us informed as to how the repair works out.

Thanks and good luck!

[chanlon]

Hello,

My Rotel 1068 processor was returned last week. Rotel, did some sort of ground modification but unfortunately the humming is still there. After 2 mths of waiting, the unit still hums.

What makes this more frustrating is that I was using a loaner Yamaha receiver as a preamp for 2 mths that costs 1/5th of the price. And of course, it was dead silent. No humming with the exact same setup, cables, DVD/SACD player, etc. My dealer is waiting on a response from Rotel.

I do understand that ground loops are complex issues. However, it makes no sense that another Rotel preamp or Yamaha preamp works OK in this setup.
The only logical assumption would be there exists an issue with the preamp. Is this safe to conclude?

Update: I just borrowed another Rotel 1068 from my dealer. This new unit is dead silent as well. I will be requesting a new unit Monday from Rotel. I'm sick of dealing with this matter.

[Kevin D]

Hello,

Update: I just borrowed another Rotel 1068 from my dealer. This new unit is dead silent as well. I will be requesting a new unit Monday from Rotel. I'm sick of dealing with this matter.

Considering the circumstances, I don't think that will be an issue.

Kevin D.

[chanlon]

Thanks for the response Kevin. I don't believe it SHOULD be an issue.

I can't believe the difference in this loaner 1068. For starters, there is no noisy relays when changing sources. No more popping sounds! There is no audible hiss unless you place your ears close to the speakers. Also, I could never get the preamp to recognize a 96K input on a Neil Young DVD. However, out of curiosity, I decided I would try on this loaner. Of course, it worked flawlessly.

Anyways, stay tuned. My dealer will be requesting a new unit tomorrow from Rotel.

[mars]

I have owned many different brands of AV gear, some mid-fi, more high-end... Rotel is the worst I have ever experienced for ground loop hum, the 1068 particularly so. A review of the posts on this forum will confirm the 1068 to be a bit infamous in this regard. I have optimized and isolated my system and learned to live with the hum that remains. Granted, most people's cable boxes are to blame (I run only an optical digital cable to the 1068 and use the TV for video switching) but that does not excuse an engineer from designing for "real world" use. In isolation the 1068 to the 1077 is pretty quiet (quieter than the 1075 or any other class A or A/B) but not entirely so, once on hangs on any assortment of equipment regardless of brand or type the noise increases. Swapping the 1068 for another pre-pro will improve but not cure. You are in good company.

[chanlon]

Hi guys,

I need your opinion again. The last I checked in, my so-called repaired 1068 processor still exhibited the same humming issues after returning from Rotel. So, my dealer asked me to connect the unit in his store and demonstrate the problems. According to the dealer, Rotel wanted the dealer to test the unit. According to Rotel, the unit demonstrated no problems and performed to factor specifications at their service center. Well, the unit clearly demonstrated the problems at my local dealer.

Anyways...Rotel has offered to replace the unit with a refurb/demo 1068 ONLY. Not a new model. I want a new model. I have a problem with inheriting somebody else's problems or demo unit. If I wanted a demo unit, I would have purchased such a model 2 years ago. I have already experienced first hand Rotel's classification of "factory specifications." As a result, I'm very skeptical about owning a used unit.

Any opinions?

Thanks in advance.

[Kevin D]

B-stock can mean several things. Usually if a customer has a problem and Rotel can only offer a B-stock unit, I request a non-repaired b-stock unit and haven't had any issues.

Kevin D.

[BluChief]

Good luck to you Chanlon, hope you get it resolved

[chanlon]

Rotel CAN offer a new unit if they choose to do so. Its a case of them simply choosing not to. My point is that I shouldn't be forced to accept a B-stock unit.
If I wanted a used unit, I would have purchased a used unit at a discounted price.

I am not a happy customer.

[chanlon]

Hi guys,

The replacment (refurbished) 1068 processor that I was provided with does not pass HD signals correctly. I use my 1068 for video switching. Every 1-2 minutes on fast moving scenes, the picture on my TV goes blurry, drops out completely, then re-appears correctly. I verified it was indeed the processor by connecting my Sat. receiver directly to the TV. The image is perfect.

I have been trying to get my original 1068 repaired or replaced. Rotel already tried to repair it but could not. As a matter of fact, others issues became prevalent when it was returned. My dealer then requested a new unit since I've purchased several Rotel products and have been dealing with this issue for months. However, Rotel insisted that they will only provide a refurbished model. My original opinion of refurbished products holds true. I was basically passed somebody else's problematic unit.

I'm seriously sick of swapping units back and forth. I'm not happy with the way this has been handled from the get go. My confidence in Rotel products and service has diminshed. Frankly, I can's imagine evey buying or recommending a processor of Rotels. Fortunately, I'm dealing with an excellent Rotel dealer who has loaned me another 1068 unit that works perfectly. I simply want to keep this unit as a solution.

I do no believe I am asking very much.