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The "KA7NIQ" Mod For The B&W 801 Matrix Series 2 ...

Posted by ka7niq (A) on August 17, 2006 at 21:51:00

I own a total of 11 pairs of speakers, including VMPS RM 40's, Von Schweikert Vortex Screens and VR4 Jr's, Magnepan SMGA's, Klipsch CF 3's, Yamaha NS200M's, Infinity IL 40's, and several more vintage models.
A couple of years ago, I purchased a pair of Matrix 801's, series 2's, with the Krell bass extender.
On REALLY great recordings, the 801's were spectacular, totally disappearing, and sounding like music.
BUT, on average or poor recordings, the stock 801's would let you know about it, in a ruthless way!
Being a music lover, and tired of listening to only the VERY best recordings, I started searching for a way to "tame" the 801's.

I came across the Van Alstine mod for them, which is pretty easy to do.

I will not get into the entire mod, but just what I consider the most important part of it.

It seems that B&W later discovered that their excellent metal dome tweeter has a peak in the low end of it's response, and it was found to cause harshness on all but the very best recordings.

The "fix" for this is to simply insert a one ohm resistor in series with the tweeters crossover coil.

It's not the resistance of the resistor that has the effect, it is the small amount of the resistors inductance in series with the coil that broadens the Q of the tweeter crossover circuit to flatten this peak.

The addition of this resistor made a big difference in making the 801's easier to live with.

After I did this mod, my son asked me to use them, and took them to his home for 2 years.

He finally gave them back to me because they no longer fit his new decor.

So, glad to have an old friend back, I hooked them up.

They still sounded good, but still "on edge" on many recordings.

So, I got an idea ... why not add some MORE inductance to the tweeter coil, and work on that peak a little more ?

So, to make a long story short, I laid em on their sides, got out the solder and gun, and proceeded to place an ADDITIONAL 1 OHM resistor in series with the 1 OHM resistor I placed there two years ago when I did the van Alstine mod.

I took all of 15 minutes to do both speakers.

I was extremely careful to place them back EXACTLY where they were, and I sat down to listen.

I couldn't stop listening for 4 hours!

What do they sound like ?

Well, 801's are always imaging mother funkers, but the best description I can give for their sound is a cross between Sonus Fabers and an LS 3/5A !

There is not a hint of any harshness, and bad recordings are now tolerable.
Imaging is even better then before, and there is a creamy Sonus Faber type sound I find addicting.

Great recordings still sound great, and so does Star Wars!
BTW, Lucas Films used the 801 Matrix as monitors.

I can not hear anything I "lost" by doing this mod, and I even have a alligator clipped wire to jump the resistors, to easily compare.

All that is "Lost" is the tweeters peak, and good freaking riddance!

The Van Alstine mod really came from B&W, and uses only a single one ohm resistor in series with the tweeter coil, instead of the two one ohm resistors in series with each other that I have found to be best.

I honestly feel that B&W tried to "save face" by only recommending a single resistor!

I do not feel they were ready to admit how bad this peak in their "perfect tweeter" really was, and how much extra inductance is really required to "tame" it!

Interestingly enough, in the 801 Matrix series 3, they added Ferrofluid, and a slightly different suspension to correct the problem!

BTW, this metal doe tweeter really is a remarkable driver over MOST of it's range, having excellent extension and air, and uncanny transient response.

I have A/B'd this tweeter with Magnepan MG3A's ribbon tweeter, and many other so called "super tweeters".
The B&W Matrix 801 tweeter can hold it's own with any of them, and actually surpasses many tweeters in top end extension.

John Atkinson is right about the Matrix series 801's, they STILL are truly a world class speaker, even almost 20 years later.

I would strongly urge any 801 Matrix series 2 owners to try this simple mod before you start shopping for "something better".

The mod is very easy to un do if you do not like it, but you will!

Just as a Porsche 911 is still a good automobile, so is the the old Matrix 801 series 2, even today.

Do the "KA7NIQ" mod to your old Matrix 801 Series 2's, and you will be rewarded with a warm, rich, imaging speaker of low coloration, that will have you tapping your toes, that you can listen to for hours w/o fatigue.

Used Matrix 801's Series 2's can be found used for well under two grand.

I know of NO used or new speaker in that price range that wants to be compared side by side to these.

Enjoy!

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