Tuesday, June 12, 2012

Fun with FM and TV

I have been finding that my Kitchen system has more clarity on FM when playing in the "Direct Stereo" mode of my Yamaha receiver.  That mode bypasses analog-to-digital conversion, DSP processing for eq and crossover and surround, and digital-to-analog conversion.  I know that the Direct Stereo mode bypasses all this because I tested it many years ago.  It's quite clear when digital processing is being done, because square waves coming through the unit have that distinctive pre and post ringing at ultrasonic frequencies.

Well usually Direct Stereo sounds better, and I think it's mainly because of the crude crossover that is being used, that crosses over to subwoofer at 100Hz or 80Hz, most likely at 12db/octave.  In the bedroom, a larger room, I cross over the subwoofer at 48dB/octave at 60hz.

I had usually kept the receiver on "2 channel stereo" because, despite the name, that is the mode that uses DSP to implement the crossover for the subwoofer.  That still works best if the deep bass is the most important part of the sound.


I've also tried some surround options.  Concert Hall uses DSP processing to get a concert hall effect out of 5 (or 7) speakers playing plus subwoofer.  It makes the normal stereo seem a bit wider.  It has the most impressive effect on a mono announcer, he sounds like he is speaking from the stage in a big concert hall (duh).


Over the second weekend in May I finally got my living room TV hooked up again to my central video system (in Kitchen).  That means I watch satellite TV and hard drive recordings and and computer and DVD's and even Blu Ray discs from the living room TV.  That was what I had set up in mid 2009, but late in 2011 the OWLink optical transmitter for HDMI to the bedroom failed.  I replaced that transmitter with the one that had previously been used for the living room, and ever since then, there has been no video system connectivity to the living room.  (The bedroom is the most important video link, I use that connection daily.)  For showing my monthly movies in the living room, I've typically used the Denon 5900 player there, and fortunately all the movies I've shown since November have been brand new (no concern about dirt from rental movies).

As discussed in this blog, I investigated several options.  I could buy a new OWLink kit for about $450.  They are very very hard to find (out of production for several years) but can be found.  There were other optical options as low as $299.

I decided to try a CAT6 balun instead.  They are much more widely available and more reasonably priced, from many brands, and the connecting CAT6 wire is a commodity product which can be readily replaced or extended.  I got the basic kind that uses two CAT6 wires.  This has essentially the same number of wires as the HDMI cable itself, so the system is relatively low cost.  Much more expensive systems manage to cram all the information into a single CAT6.

Setup was actually quite easy.  The hardest part was running the two CAT6 wires, but even that was fairly quick.  I had bought the 50' CAT6 wires from two different Best Buy stores, but they worked fine together.  I also hooked everything up to make sure it worked before running the CAT6 cables behind the couch and under the kitchen counters.  That pre-testing made running the cables harder because the cable became a huge snarl rather than a small roll that could be simply unrolled.

Another trick was getting rid of the audio hum.  After the HDMI through balun from the kitchen was connected to the living room TV, the audio output goes into Analog 1 of the TACT preamp.  There was a bad hum after hooking up the HDMI because of ground difference in the two powerline circuits.  So I used a Radio Shack isolation transformer on the audio line, and it fixed the problem.  (Now if I could only get KPAC to fix their hum problem.)  I plan to replace the Radio Shack isolator with one from Jensen that I use in other locations.  The Jensen transformers are very good, but also this is only TV.  If this were a high resolution audio line, I'd figure out some other solution.  The main other solution would be going back to fiber optic  HDMI.  I was hoping I wouldn't have to do that, and it has turned out that I don't need to, but I did need to use an isolation transformer.

I also took the opportunity to add the DVI-plus-Audio--to--HDMI adapter to the DVI line from the Anchor Bay DVDO.  That means the audio signal is sent down the HDMI connections to living room and bedroom from the hard drive recorder.  I had been using that for several months now, but it got taken off during the massive rewiring on the previous weekend that moved DVDO and HDMI-switch into the main rack for reliable remote control from all rooms.

I also replaced the 15' HDMI cable (borrowed from the Mac-to-Bedroom-TV connection) with a new 12' HDMI from Blue Jeans cable.  That means I got the Mac-to-Bedroom-TV cable back, for use in the bedroom as intended.

The system currently lacks a "rental" dvd player because that unit, a Denon 2910, is still under the table where there is no no remote control (I've given up trying to get remote down there through wireless transmission, that was the whole point of the rearrangement) and no HDMI connection to the main switch.  Probably that player should be moved to the main rack also, so it can be controlled by remote.

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