Just curious if anyone knows..

it's a secret guy...... 

Apparently it was costing them too much to make and hold the price point.

They change their line up fairly frequently. Not different from some other manufacturers. It helps sales. Nothing wrong with what you already have.

Why did Audio Research do away with the SP-6b?

So they could sell the SP-6c,d,e ...  Had the 6c and wish I still had it. Have a Sp-9 MKii now, close but not quite the same.

JD

that's what manufacturers do. if you are happy with it then why worrying if its discontinued ? :)
it was pretty popular and you will still be able to sell it after sometime as some turntable tend to be more wanted after discontinued...

I have no problem with it...just seemed odd. I think Clearaudio has been making the same competing table forever now.

Shoot VPI an Email and ask them. I’m sure they will give you the answer!

Not odd at all. Some manufacturers like VPI change models frequently, and some like Clearaudio do not. Nothing about making a record go round has changed much in the last few years

Actually VPI tends to make incremental improvements. Almost any turntable they ever made can be upgraded as they make advancements. 
That is why their older turntables sell for so much on Audiogon. And they all sound good. 

You have a great turntable.Enjoy it.

Ask VPI...They are known for great communication and honest answers to questions, great company.

I guess you guys were not around when Audio Research rose to pre-eminence based mostly on HP's adoration of their amplifiers and preamps.  The SP3 preamp went to 3A, 3B, etc, in a matter of several months.  I cannot even remember where it all ended with that model.  The Dual 50 amplifier rapidly went up to at least Dual 50F-1B.  On the amplifiers, it was almost a necessity, as the Dual 50 had a habit of blowing up for one reason or another, and Bill Johnson was constantly making changes to improve reliability, which in turn affected sonics.  My good friend, who owned a Dual 50, was in the habit of saying that the amp was only safe when unplugged.VPI changes names, rather than adding suffixes.