Thursday, October 14, 2010

From Krell to Lavry

The last month has been harrowing in my audio explorations.  It began with me tackling on of the bigger annoyances of my main system, the tendency of my Krell FPB 300 amplifier (which I love dearly for its natural sound) to make fairly loud mechanical noises like klinks (or pings) from time to time.  I could now write at least 10,000 words on this subject.  I think the problem can be solved on my unit (eventually the problem was solved in later production I hear) but I haven't gotten there yet.  I read on Audiogon that the klink problem can be solved by loosening all the screws on the case just a little.  So I tried that, didn't help.  I even got a precision set of Wiha torque control drivers ($200) and precision torqued one whole side to an exact setting.  That seemed to make matters worse, actually.  Before that, I had moved the Krell into the corner and out-of-the-way from the periodic A/C blasts.  That didn't help either.

After all this messing around with the Krell, moving it in and out of the corner several times, working all the vast numbers of Torx screws it has many times (I had to overcome great trepidation before loosing screws on the heatsinks, I was afraid that might destroy the amp), I noticed something bad.  One side was getting very hot, too hot to touch for more than a couple seconds.  Even just idling it would do that.  After a bunch of torque tests, but just before that discovery, I had left the amp idling for a few days thinking that might help the chassis metal plates find their natural position with the new lower torque.  That was when I noticed how hot the amp was getting on one side only.  Actually, I think I might have noticed one side being hotter than the other for a long time, but I hadn't realized it got that way just by idling.  I put a Kill-a-Watt meter to see how much power it was using.  But before I put the meter on, I shut the amp down for a couple minutes.  Then I turned it on, and noticed that the power consumption just kept on increasing.  Finally, in a minute when I wasn't watching, the amp got so hot it shut itself off.  OK, it has to go back to Krell again to fix the bad left channel.  Last year it had been back to Krell for a bad right channel.  Hopefully after enough things get fixed, it will stay fixed for awhile.  I bought the amp apparently working 3 years ago, but I think it had been just about ready to break from 10 years usage.

So then I had to switch to another amp in my amplifier collection.  Fortunately I had just purchased a nice Parasound HCA-1500A as an upgrade for the amplifier in my bedroom.  But with 300W at 4 ohms, that has enough power for the living room Acoustats as well.  When that Parasound amplifier had arrived in August, I was thinking about testing it on the Acoustats.  But I figured it wouldn't be as good as the Krell, so I didn't bother.  Well now I was forced to try it.  And it seemed to play OK without shutting down (I tried a lower power Parasound HCA-1000A once, and a moderately high level it shut down from overheating).  It sounded pretty good.  But it lacked the incredible natural depth that the Krell has always provided.

Just about then, the first Belkin PureAV power conditioner arrived.  At that time my living room audio wiring was a total mess and without massive reorganization I wouldn't be able to fit the Belkin in.  So I embarked on a large reorganization, moving all the line level equipment from the left side toward the right side for connection to the power conditioner without extension cords or power strips as had been required previously.  About two boxes of unnecessary or too-long cords were removed.  So the wiring had gotten much simpler and shorter and there was now a power conditioner.  A handful of long interconnects got replaced with shorter versions, but for this post I'm not mentioning all the specific changes made.

The result, after the conditioner had been installed, and the wiring layout cleaned up, was a considerable improvement in sound.  "The blacks got blacker" as they say.  This actually restored much of the depth that had been lost when I swapped out the Krell amplifier.  Playing classical FM radio, the sound was just about as good as it had been with the Krell.  But not quite.

So then I decided to try another upgrade that had been waiting to be installed.  My main system is based on digital signal processing for crossover and room equalization.  This works wonderful with digital sources because the signal is already digital, and digital signal processing is as close to perfect as it gets.  But analog sources, such as FM radio, must be converted to digital for me to even listen to them.  The Analog-to-Digital converter (ADC) in my Tact 2.0 RCS preamp is only so-so.  It's supposed to be 24 bit (from 1999) but only has 16 bit performance according to a review in Stereophile and my own testing.

I had already purchased a much better ADC, a Lavry AD10.  This has 24 bit operation with 120dB signal to noise ratio, about as good as it gets.  The Lavry (and it's even more expensive brother, the Lavry Gold) are highly praised by recording engineers.  BTW it is priced at $1480 and I ordered mine directly from Lavry in Washington State.  I always feel good when I can buy top quality equipment made in the USA.

Replacing the Tact's built-in ADC with the Lavry was a revelation, vast improvement in depth, deep bass, transparency, coherency, everything.  Now listening to FM radio is even better than it was when I had the Krell online, though for different reasons.  Hopefully it will get still better when the Krell is fixed and back online.

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