Wednesday, November 28, 2012

More fun with Kenwood L-1000T

Just a few weeks ago I hooked up my Kenwood L-1000T (aka Kenwood in this post) to my whole house Sonos audio system using a Behringer DEQ 2496 digital equalizer to correct the European 50uS deemphasis to the USA 75uS standard.  In the digital domain I can do the conversion quite well, even with the limited choice of cutoff frequencies.  I use a 6dB per octave shelving at 2212Hz.  Right now I can't remember the dB of adjustment but I think it was between 2 and 3dB (calculated in an earlier post).

Well of course I couldn't even enjoy the Kenwood over Sonos without this change (or something having a similar effect, like actually changing the parts in the Kenwood), so even though I had hooked up the Kenwood to Sonos back in July, I hadn't really used it much for the Kenwood.

What I mostly use this for is listening to radio in the bedroom.  The bedroom currently does not have any tuners hooked up (though, ironically, I have the stack of second best tuners that the Kenwood defeated now resting in the bedroom because the computer room has been overstuffed with junk).

When I used the Sonos system to listen to FM, which wasn't that often, I usually listened to the Marantz 2130 in the kitchen as it has the correct EQ and actually sounds very nice.  Sonos lets me pipe a line-input signal from any room to any other room, it goes through a moderate quality 44.1Khz 16 bit uncompressed codec with digital level adjustment so you can optimize the dynamic range.

This was a revelation.  The Kenwood always sounded great, but now I could actually stand listening to it for hours, and using my KT-6040 remote control, I spent one evening scanning radio stations.

On Tuesday night I found how the Kenwood L-1000T with correct EQ really blows away the Marantz 2130 over Sonos.  The Marantz sounds veiled and muddy by comparison.  (It doesn't sound that way at all in the kitchen, possibly because of different room acoustics and near field listening, but also possibly this test is unfair, I have fully optimized the Sonos level for the Kenwood a few days ago, currently max tuner output gets to -3dB digital maximum, but the Marantz level in the Kitchen has not been optimized, and was about 20dB lower, causing huge loss of digital resolution (though I raised the volume level to compensate, it can't restore the resolution lost over 16bit depth conversion and transmission).  Possibly the Marantz level actually depends on the volume level I set on the amplifier in the kitchen, actually a Yahama receiver.

But I also came to notice on Tuesday night this week that the signal from San Antonio City College was mono.  I noticed this because I happened to pipe the Kenwood output to the kitchen system, and look at the stereo separation on the L-R scope mode of the Marantz.

So I took a careful look at the display of the Kenwood tuner.  It was showing only one (tiny) bar of signal strength, yet the RF selection was Direct.  Obviously this was causing a weak signal and limiting stereo separation.

For some time now, I had been convinced that the 6040 remote doesn't control the station control settings on the Kenwood.  But somehow I had pre-programmed Preset 2 for Direct mode.  Either I had actually set the Direct mode somehow, or at some earlier time the signal strength may have been stronger when I was setting the presets.

I was able to un-set the Direct mode by this procedure:

a) Disable setup mode using small button to the right of tuning knob.
b) Change the tuning by the minimum amount in either direction.
c) Change the tuning back to the correct center tune.

This forces the Kenwood to determine the best settings for this station, and when I do this now, it correctly choses High Sensitivity mode.

Now the fact that the presets had been programmed with direct mode suggests that possibly I had been able to control the RF mode previously, and I had deliberately chosen direct thinking it would give the best sound quality.  Or, more likely, I had set direct mode for KPAC, a much stronger station, and had failed to unset it for the remaining stations that I programmed.

Taking the remote in hand again, I struggled and with much fiddling with angle and direction was able to get the Kenwood to change RF mode once.  I think the capability is actually there, I just lost it when I stuffed the Kenwood into the corner it now occupies, which gives no good way to aim the remote at it (the Kenwood is immediately behind the transformer of my Acoustat speaker).  I can try to control it from the side that I have open and it sometimes works.  I can also use the Remote Extender system which I use to control the preset station selection from the bedroom.  That also has a receiver over the living room mantel so I can point the remote at that rather than at the tuner.  It works, mostly, for setting presets, but may not have enough IR resolution for the advanced settings like the RF mode.  The remote extender has a transmitter I place just to the side of the L-1000T and it works, at least it works well enough to change presets.

It may also be the batteries in the 6040 remote have gotten weak.

I need to experiment with this more, it was already well past my bedtime when I made the above discoveries, and I decided to stop because I know these kinds of explorations can last all night and typically end on some frustrating note.  But I will be back at it soon.

In the meantime, I used my mis-tuning method to get the Kenwood back to receiving the city college station in High Sensitivity mode.  But if I change the preset, this gets messed up, so I really have to find some way to fix it.  I could also memorize the preset with the High Sensitivity mode.  But I also forgot how to program presets, I alway find this confusing and counter-intuitive on Kenwood digital tuners and I need to read the instructions again.

But another flaw is that I can't, or at least was unable, set the IF bandwidth.  When I change the RF mode back to High Sensitivity using the method above, it also resets the IF bandwidth to Narrow.  It really doesn't need to do that I think, as Wide works fine on Direct mode, it should also work OK on Narrow.  But as yet I haven't figured out a way to change that.  Perhaps the remote will do this, and perhaps it won't.

Here's a discussion of HDMI/HDCP handshaking.

There are endless blogs of people describing issues and frustrations with Apple's Mini DisplayPort.  Many people have suffered with the disappointment that they cannot use their cherished display with their cherished Mac.  And for many of those people, the problem did not go away the next day.

After you look at the discussion of HDMI/HDCP handshaking, it's not surprising that this technology is so finnicky.  HDMI/HDCP want to make sure you're not doing anything that isn't allowed (recording!).  And it seems, even a slight seeming irregularity will shut them down.  Also, all HDMI/HDCP units have an internal state, which may need to be reset by powering down the unit for 10 seconds.  You try powering down everything, making all the connections, then powering up switches, then displays, then sources.  If that doesn't work, try powering down everything and then powering up switches, sources, and displays.  Some configurations work better with powering source first, others with powering display first.

Oh Boy.

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