Tuesday, April 10, 2012

L-1000t specs

Stereo Separation: 71dB IHF, 68dB DIN, 48dB DIN at 6.3Khz

(Comparison: L-02t: 55dB, or 45dB 50-10Khz, but probably not DIN)

50dB quieting
Mono 1.8uV
Stereo 24uV

(I remember when tuners had 1.8uV for 30dB IHF sensitivity, maybe hit 50dB at 10-20uV.  However, these numbers are almost exactly the same as L-02t.)

IHF S/N at 65dBf
Mono 92dB
Stereo? 78dB but improves to 86dB at 85dBf

(*The service manual specs repeat the word mono.  I'm guessing they really meant stereo, which fits the numbers.  These numbers are not as good as L-02T, which shows 95dB in mono and 85dB in stereo.  Note however they probably applied the trick of increasing RF level to 85dBf, just without mentioning it, so the numbers for 1000t are almost in good in mono, and slightly better actually in stereo.)

 THD (non-Europe)
Mono 0.004%
Stereo 0.008%
(50-10kHz in stereo, 0.04%...many tuners go above 1% at 10kHz)

Wide has 73dB alt ch selectivity (as much as many narrows).  Normal has 80dB.  Only 300kHz spec available for Narrow, and Kenwood never specs adjacent channel selectivity.

Normal just a bit more THD than wide.  No spec for narrow.

20-15,000Hz, +/- 0.5dB

OK, now for the killer specs, the specs that kill varactor tuners generally:

Spurious Rejection  110dB
Image Rejection 85dB
IF Rejection 110dB
AM Rejection 80dB

Well not too bad, for a varactor tuner.  I believe the TU-X1 has spurious rejection at 130dB.  The L-02T shows 120dB for everything above except AM at 70dB.  The killer is the image rejection at 85dB.  That's quite good for varactor tuner, actually, but just doesn't compare to L-02T at 120dB.  35dB worse. That's the measurement of how well the tuner rejects unwanted image products.  That causes overload in severe conditions probably not of much importance to me, but also constantly adds small amounts of distortion that need to be filtered away downstream.  The L-1000T does suprisingly well at that filtering out downstream.  By the numbers, it looks about the best MPX performance ever, which is all the more fantastic given that it doesn't have the best front end ever.

Some crazy guy (see my sidebar) used an T-85 as a multiplex adapter.  Imagine using a L-1000T as a multiplex adapter on a fantastically good analog tuner.  I could use it on F-26, which is fairly fantastic down to the detector, and even all the way.

AM rejection, FWIW, is better than any analog numbers I've seen, but I don't think that's a good measure of susceptibility to EMF pulses, which generally ganged capacitor tuners do much better than varactor ones.

But will it have soul?

I think ultimately I will have very narrow beam antenna set up.  Meanwhile I usually use folded dipoles which don't give maximally strong signals and are somewhat directionally sensitive.  So the front end limitations are probably not a problem for me.  But I do notice random clicking sounds from varactor tuners more.  The XDR-F1HD is the champion clicker.  But I'm pretty happy with high end varactor tuners like KT-6040 especially.  But I already have F-26 tuner which gives me both air capacitor top shelf RF performance, and the grown up MPX performance which wasn't available until, well, the F-26 (wasn't the L-02t later?).

So here's the sad part, in a way.  It looks like the L-1000t may improve on the KT-6040.  But perhaps not so much on the things that represent the weakest part of the KT-6040, it's mediocre RF performance ultimately limited by being a varactor tuner.  It simply can't reject mixing products, or ultimately EMF pulses, as well as an air capacitor tuner.

So I'm really coming down on the side of Anonymous Dave and his fairly quick dismissal of this tuner.

So about the only question left in some people's minds might be why I bought this tuner.

But I'm going to finally throw a catch.  One part of the audiophile canon is that the front ends of things are most important.  I would agree that this is disproportionately true, and completely true in certain cases, but not always or generally true.

For example, take distortion.  If a front end adds distortion, it cannot be removed.  (Well, sometimes it could be...)  And further, following stages will accumulate distortion on the distortion, so generally give two stages A and B with A having lower distortion, you will get less distortion putting A first.

But this presumes that you only have A and B to work with.  It may be, that you don't have A, you have V, which has a tad more distortion.  But perhaps, either in theory or availability, V as stage one permits the use of a following stage M which has far lower distortion than B.

The approximate number is the product of the two available numbers.  So if using a slightly higher distortion permits using a much lower distortion second stage, AND assuming the second stage was a significant contributor (! which may be a catch here and many other cases !), you can make a better product by improving the second stage.

And those are the choices that are left to us.  We might like to have a most excellent tuner front end combined with the best available mpx, but unless you can build that mpx adapater, pretty much you are stuck.  Available mpx adapters are either ancient history, or perhaps not the best chips.  The best of all mpx are those within tuners such as the L-1000T.

OK, now that I've made this argument, let me say that I have not yet fully accounted for the nature of the pieces of the tuner.  And when this is added up, the full benefit of the front end is hidden because the specs wrt the multiplex section are measured under laboratory conditions.  Even a tuner with a 60dB stereo S/N specification like the XDR-F1HD can sound perfectly quiet, if it only stays at 60dB.  That's the rub.  RF is a jungle, and you need good RF stage to keep that jungle out, and the MPX specs are not really telling you how well the tuner can do that, even when there is no apparent problem, images are finding there way into the audio and adding invisible noise and distortion, invisible because it is "masked" but adds a greyish or grainy quality to the sound.  It is not hard for the percentage of distortion passed through the mixer to be far greater than that of a decent mpx section.

We'll see.  I actually thought the KT-6040 was a fine tuner, and the benefit of the F-26 was, well it was not the sort of thing that would be described by the apparent noise.  The F-26 has soaring musicality, as do the KT-8300 and Marantz 20B in their ways.  The 6040 was less fun to listen to, just a nice quiet tuner.  The F-26 shared the quality of the 6040 that it is harmonically accurate (unlike 8300 and 10b) and quiet (in the cast of 6040 it is apparently quiet...as I described in previous paragraph.)

Would be funny if the 5 gang Marantz 2130 had more musicality than L-1000T.  Like the F-26, the 2130 is a late generation analog tuner with a mpx similar to later digital units.

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