Sunday, February 3, 2013

Tuner Switcheroo

Kenwood L-1000T 2nd from bottom
On the night of Friday February 1st it was becoming clear that I was hearing distortion from the Kenwood L-1000T quite frequently, not just on certain bass heavy programs like Pipe Dreams.  It still does seem that usually the distortion, which has a garbled clipping sound that persists for a few seconds, is usually triggered by audible low bass.  But sometimes it occurrs even when there is no audible bass.  I reason that there might be subsonic bass that is triggering it then, but this is all guessing. Guessing further, I suspect this is being caused by a power supply droop or decoupling capacitor failure.

On February 2nd I did some careful testing to confirm that the distortion is coming from the Kenwood itself, and not my incredibly complicated setup, especially for whole-house listening through Sonos--I actually do most of my listening on kitchen system which has Sonos box. I send L-1000T variable output to a Lavry AD10 which converts to 24/96 digital, then to a Behringer DEQ 2496 for EQ correction, then in analog to Sonos which digitizes again for whole-house distribution.  When I'm listening in the living room, I take the digital output from the Behringer straight into my Tact preamp so no analog re-conversion is necessary.  To bypass much of this, I took variable (and then fixed) output from the Kenwood into the Lavry, then to the Tact, doing the corrective EQ in my DCX 2496 crossover.  So I never did bypass the Lavry, which I believe is working fine.  Analog sources has to be converted to digital somewhere for my living room system to work.  I trust the Lavry, though in a quick online search on Saturday night I was unable to find the input impedance of the Lavry and I had been worried it might be too low, something like 600 ohms, though I believe it is more likely to be 10k ohms or higher.

At first, it seemed like the distortion was not occurring on the Living room system with Berhinger DEQ bypassed.   Strangely, I first noticed the distortion when I was listening to the living room system while in the hallway.  The living room system is so transparent, it actually minimizes certain kinds of distortion.  When I did finally hear the distortion, it seemed briefer and relatively softer.  I sat down and listened to L-1000T in the living room for about an hour, by which time the intermittent distortion was unambiguous.

So I removed the Kenwood from my left hand stack, stashing it in the master bedroom for later investigation and repair.  Meanwhile, my motto is that the symphony must go on, so I brought out spare replacement tuners.  I first hooked up the Kenwood KT-6040, a tuner I thought was one of the best a couple years ago.

Switching from L-1000T, the sonic inferiority of the KT-6040 was all too apparent.  I was so disappointed at first I toyed with bringing back the L-1000T and just ignoring the distortion.  But that distortion gets on your nerves after awhile, you find yourself cringing when you expect it, and the L-1000T needs repair before it gets any worse.

The KT-6040 is equally quiet, but lacks the depth and spatial and harmonic realism the L-1000T has.  It sounds as if the 3D reality of the L-1000T is chopped up into tinfoil panels, one for each musical instrument.  The tinfoil panels are placed in front or back of each other, giving some kind of depth, but nothing like reality.  At the same time there is a cotton-ball like fuzziness to everything, even though there is no lack of highs, maybe even slight excess, but the worst is that the highs seem slightly disconnected from their fundamentals.

I was so disappointed with the KT-6040 sound I brought out the Pioneer F-26.  I'm not sure my F-26 is operating correctly because the "Wide" light never lights up for any of my favorite stations, if at all.  But nevertheless, the F-26 had a far more listenable presentation, a greater sense of coherency and consistency.  The F-26 is also rolled off a tad and perhaps slightly less transparent than the KT-6040, but far more pleasant to listen to, especially in the ultra transparent living room system.
KT-6040 2nd from bottom, F-26 3rd

So I decided on a hybrid hookup, with F-26 hooked through Lavry to play only in the living room, and KT-6040 hooked up through Behringer (using the Beringer A/D conversion also) to play in other rooms through Sonos.  The 6040 sounds OK through Sonos, maybe even better than direct because the highs are slightly tamed.

When I bought the KT-6040, and even the L-1000T I figured I would have a dual tuner setup like this. I had not figured on the L-1000T trouncing my F-26 sonically and therefore being able to play both roles.

Because the remote I have been using with the L-1000T is actually a KT-6040 remote, I was actually able to control more functionality on the KT-6040 than with the L-1000T.  For the first time, I was able to do tuning scans to find new stations.  I spent some time doing that on Saturday night into Sunday morning, checking out some new rock stations.

[Note: the ISOMAX transformer and Classe CP-35 preamp in the left stack are used with my Kurzweil K2661 keyboard.]

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