Saturday, July 29, 2017

Don't rely on me !!!

I see many times over I've been wrong about many things.  The record is so endless I couldn't possibly be expected to correct every past mistake.

I especially feel guilty about declaring people "late" (dead) when they are not.  I may have done that wrt the wonderful Keith Johnson.

One of my bigger mistakes, back in about 1985 or so, was to decide to bypass the internal crossovers in my LS 3/5 A speaker, which which I had a love/hate relationship (especially after having blown two modified T21 tweeters...a tweeter whose high end always sounded wrong to me, and I blamed the  perforated metal foil around it.  But equally as much, the T21 wouldn't take much before burning out, I discovered.

I discovered the Dynaudio D21AF tweeter sometime before then, perhaps around 1979.  I used them with the Advent speakers in a previous bi-amplified setup (something I have long believed in, and practiced).

I bought a Pioneer D23 3 way 6/12/18dB octave crossover, and used that with the D21AF and the B110 woofer inside the LS 3/5 A.  I wired both drivers straight to the outside, and removed the crossover board.

A friend of mine gave me a severe dressing down for daring to mess with the engineering of the LS 3/5A in such a gross way.

It turned there was some truth to what he was saying, as I discovered around 2003.  I discovered that my re-engineered LS 3/5A, which still sounded excellent to me (except the D23 which had been "on" all the time was beginning to hum a tiny amount) had a very serious peak, about 10dB or so, at 1kHz.

The reason was the doped bextrene driver itself...which had nice properties at other frequencies being light and rigid...had a resonance right there.  Much of the complexity of the LS 3/5 A crossover was the mitigation of this 1kHz peak.

In all the reams of consumer writings on the LS 3/5A I had never seen any mention of this.  Perhaps they were hiding the crude nature of the by early 1970's driver technlology.  Instead, it was said, the crossovers performed the magical trick of providing sufficient bass, by boosting the response at 120 Hz because of the lack of bass at 60 Hz.  Actually, I don't recall anything specifically like that when I examined the crossover.  But if you disengaged the 1000 Hz peak cancellation, the bass at 120 Hz and everywhere else will get relatively lower than the reference frequency 1kHz, so, yes, the 1000 Hz cancellation does sort of enhance the bass...and everything else that isn't 1000 Hz.  (I think this shows the danger of relying on "public" information, which is often highly affected by spin.)

Anyway, before just diving in, I should have done measurements, I believe now.  It's pretty obvious actually.  But I didn't bother, I just connected up the crossover, and boom, I could have anything I wanted, including the magical 12dB/octave linkwitz riley, which makes more out of less power at the crossover (both sides are 6dB down at the crossover frequency) by projecting more efficiently toward the listner.  (Now, btw, I strongly prefer the double order Linkwitz Riley crossovers such as 24 and 48 dB/octave, because both sides can have the correct polarity.)

So, anyway, for 18 years or so, I had a huge midrange peak.  The bass was relatively attenuated to 1kHz, making for a slightly thin sound (I was also using a pair of McIntosh ML2's as subwoofers... another interesting story...).  But I did have full spectrum response which sounded very very clear and transparent and I loved it.  I always loved the top end, which I believe extends to 40 kHz, of the D21AF tweeters.  It appears nothing like it has been made since, the later far more expensive Dynaudios have been larger and with more low end capability and clarity.  It seems manufactures of cloth domes don't care too much about 20-40kHz, the range for a decent super tweeter.  They are endlessly trying to give tweeters better low end for woofer integration.

I have however found one 3/4 inch Vifa speaker, only $33 at Madisound, with rated response to 40kHz (where, it is 3 dB down).  That's what I may use in combination with the D21AF pair I have, as supertwetters.  The superb D21AF's would go in front, and the Vifa's facing backwards.

Anyway, regardless of how "wrong" I was, I loved my ultimately tri-amped system.  It felt great to have something sound so transparent and with deep base and clear effortless transparent highs.

When I got my Revel M20's, it was absolutely clear these were the more transparent and full sounding speaker.  And I have relied on two pairs of M20's since around 2005, one in kitchen and one in bedroom, and the bedroom was the Main System until I got Acoustats in 2008.

I wouldn't say however, that I have actually loved the M20's any more than what I had before, before I discovered how un-neutral it was.

I had fun making my own mistakes, relying on my own judgments, even if they were wrong in some ways.  And...they were actually right in other ways...the extended highs of the D21AF are fabulously effortless and transparent, and no peaks either.

But if you want to get things right the first time, every time, etc., then don't rely on this blog.  I'm not promising that.  Only adventure and discovery, ocasionally correcting earlier mistakes, but always having fun, and thinking on as grand a scale as possible, perhaps about not much of anything.

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