[kbuzz3]

Ive had a nasty ground loop after switching over to my new D-sonic amp in my Ht system. As typical in these situations, the culprit was the cable tv box.  I tried out an inexpensive ground loop isolater from TII technologies which solved the problem elegantly.  However, my ears tell me that the volume is reduced slightly and dialog is a bit harder to hear.  I dont see why as I use the HDMI out form the cable box to my processor.  So folks is this an illusion?  Would I be better served by a more expensive model like the oft recommended Jensen?  Thank you in advance for any thoughts or comments and recommendations.

Maybe the low cost  T2 solution is too aggressive on flitering?  Here is the T2 product info : http://www.amazon.com/TII-220-Ground-Isolator-applications/dp/B0070Q6URO/ref=aag_m_pw_dp?ie=UTF8&m=A1SRR0B7QVPEN. Or here : http://www.tiitech.com/repository/datasheetlibrary/NYMDS039-0710.pdf Specs are:

RF performance operating at a frequency range of 5 - 1,000 MHz.
Maximum insertion loss is 1.5 dB. at 1 GHz.
RFI shielding of > 85 dB.
RF PERFORMANCE:
RF Bandwidth: 1MHz-1.0Ghz
Impedance; 75 Ohm
Insertion Loss; <0.5dB
Return Loss;>24.0 dB[/b]

Here is the Jensen at $70 bucks: http://www.jensen-transformers.com/product/vrd-1ff/

specs:
Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 MHz to 1300 MHZ
Insertion Loss (typical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.19 dB
Capacitance (output shield to input shield, 1 kHz) ....................................... .............. 2000 p




Insertion loss   5 MHz, HP 3577A Analyzer       -0.19 dB   
Insertion loss   50 MHz, HP 3577A Analyzer       -0.01 dB   -0.1dB
Bandwidth   LF -3 dB re 100 MHz, HP 3577A Analyzer       1 MHz   1.2 MHz
Bandwidth   HF -3 dB re 100 MHz, HP 8711A Analyzer   1000 MHz   > 1300 MHz   
VSWR, input or output port   50 MHz to 866 MHz, HP 8711A Analyzer       1.08 (see graph)   1.2
Input to output voltage               200 V DC
Externally Radiated Field at 3 Meters   Ref. level = 1.414mVrms, Frequency = 50MHz       1.1uV/meter   
Externally Radiated Field at 3 Meters   Ref. level = 1.414mVrms, Frequency = 500MHz       4.8uV/meter   
Externally Radiated Field at 3 Meters   Ref. level = 1.414mVrms, Frequency = 1GHz       6.3uV/meter   
Margin below FCC part 76 Limits   Ref. level = 1.414mVrms, Frequency = 50MHz       25.6dB   
Margin below FCC part 76 Limits   Ref. level = 1.414mVrms, Frequency = 500MHz       12.5dB   
Margin below FCC part 76 Limits   Ref. level = 1.414mVrms, Frequency = 1GHz       10.1dB   
Cable length   output       2 m (6’)   8 m (25’)
Isolation Impedance   output shield to input shield, 60 Hz   1 MΩ   1.3 MΩ   
Capacitance   output shield to input shield, 1 kHz       2000 pF   

[Phil A]

AVA makes one (http://www.avahifi.com/index.php?option=com_content&view=article&id=270:ava-humdinger&catid=41:special-functions&Itemid=256).  I have and use this (bought for a problem in my old house) - http://www.amazon.com/gp/product/B0002E4YI8?colid=321FECHQA1Z6W&coliid=I2I3VNO4OQRS43&ref_=wl_it_dp_o_pC_nS_ttl

[kbuzz3]

Phil

Thanks for the reply.  The Ava product looks great but I believe it's for transformer hum and mine is speaker hum

The other one also looks easy to use.  My inquiry is really whether one product will sound different

[Phil A]

There are probably a fair amount of comments about it on the Van Alstine Circle.  I had hum in my old basement coming from the subwoofer that was likely picking up from a fan in a projector (which I made a long custom extension cord to and tried various things) and had no hum on audio.  So it instantly resolved the problem.  I've seen websites for building a simple device to get rid of cable hum and other things such as - http://forums.stevehoffman.tv/threads/eliminating-system-hum-from-cable-tv-box.137091/ or  https://www.native-instruments.com/en/support/knowledge-base/show/250/how-to-resolve-ground-loop-issues-humming-and-buzzing-sounds/   or  http://www.ecoustics.com/articles/eliminate-hum-buzz/   or  http://www.audioholics.com/home-theater-connection/ground-loops-eliminating-system-hum-and-buzz

[rif]

I had a ground loop issue in my HT, here's what I remember.

You need to do some research on coax isolators. I couldn't use them in my system since fios uses coax to transmit digital tv/internet/ethernet/moca etc. over standard coax.

IIRC, the culprit was actually coming through the hdmi cable.  That doesn't sound right in retrospect but that's what I remember. Unplugged the hdmi, hum would disappear.

My solution - buy a BASH sub amp which uses a two prong AC cord. Problem solved.

[Wayner]

One problem that may arise with a HT setup is the fact that because there are so many components to power up, the system ends up on a couple of branch circuits. In my books, this is a no-no and it invites 2 different ground paths (because each ground has its own, theoretical level) which then invites all of the components that are interconnected with audio cables to have conflict with the ground path. If this is the cause (not a cable box), the solution could be to connect everything to one outlet (if the amperage will allow), so that there is only one ground point.

Wayner

[riffer]

Just get the Jensen.  I've had one for years.  I did some testing a few years ago when I had some problems with cable reception and found the signal loss to be negligible.  (as usual it was the cableco's problem).

One thing about the Jensen, and presumably other devices of it's type, I found that putting it at the beginning of the 20' run to my cable box worked better than at the other end.  This is covered in Jensen's documentation.