Maybe Mr. Tabalt11 can get Jeff Green from the Pickniks to weigh in on this.
Jeff is Mr. Jazzmaster and has Bob's tone down pat.

Thanks Walt.  I appreciate your kind words and consider them as an ultimate compliment.

There are many factors involved that contribute to the sound an electric guitar will produce.

Sticking only to the Major Factors these are: The Guitar - The Amp - The Strings - The Pick

The Guitar:

As for my choice of guitar,  I pick the Fender Jazzmaster as my favorite. Although it's unknown to many,
this is a very versatile instrument, that is capable in a wide variety of musical situations.
And as a choice for an instrumentalist's guitar, in the vein of The Ventures, Fireballs and other groups of
of that similar style, it's tops.

To find that Bob Bogle sound, I find I that it can be obtained using one of the new Fender Vintage Models.
I've had '59, 63, 65 & '70 Jazzmasters, but the new guitars are so well made and so easy to play and
are actually consistantly better made than the "oldies". These new guitars are not cheap of course, as they now list around $2400.00.  But try to get a real vintage model and you'll have to take out a 2nd Mortgage!

My life with guitars goes back to when JFK was President of the U.S.A., so I've truly had a lot time to
"experiment".  The old Jazzmasters for the most part are more mellow than the reissues. The exception
is that '65. Wow! That guitar will clear out your ears! Good sounding, but extemely penetrating treble!
The '63 was a great guitar.  The '70 didn't play or sound so good.  The '59 sounds really good, but it
doesn't paly as well as the others.
So.....my description here is based on the Fender Vintage Reissue Jazzmaster.
These guitars are not naturally as sharp as a Telecaster or Stratocaster usually is, but you can get mighty close if not right on that sound just but adjusting your guitar and Fender Amp.
Still, the guitar is naturally very bright. To achieve an Early Ventures Sound, that brightness has to be reduced.
Here's how:  Leave the Tone Knob on full, but back off the Volume Knob to about # 7.
No power problem if you're playing though a Twin Reverb as I usually do, as there is plenty of reserve power.

The Amp:

Set the Fender Twin Reverb Amp at about 6 Treble, 6 Middle and 6 Bass. Of course this will vary with every
Jazzmaster and Twin Reverb.  You can use the same guitar through another Twin, but it's likely the settings
will not work out quite the same. 
You go ahead and set your Reverb or Delay and Vibrato/actually Tremelo to suit your tastes.

The Strings:

Lots of controversy here.  But I played back in the days of those thick, heavy strings. when light gauge strings
were unheard of, were unavailable.  Those strings were tough on the hands and tough on the frets.
Soundwise, they are more mellow then light gauge strings, but I can get the same sound with more comfort
with a 9 to 46 set of D'Quisto Set #325 Strings. Which, by-the-way, I understand is the same gauges Nokie
uses, or has used.  Also the light gauges strings are easier to bend, the vibrato works better and my hands
are happier!  I don't pick very heavy, I have a very light touch.  I don't like to hear any buzzing and rattling
when I play.  I let the amp do the heavy work for me.  Playing this way, gives me my best tone.
You don't always achieve that perfect tone, but as Wes Mongomery put it, "You get it close as you can,
to a tone you that can live with."
Bad news: D'Aquisto Strings just went out of business recently. So now what am I going to do?
I don't know yet, but I bought up all the Set #325's I could find.
I have 24 new sets, so that will tide me over for awhile.

The Pick:

I use a very small pick. It's teardrop shaped and it's thin. Ordinarily this is another factor that will produce
treble and of course it does. But I adjust the guitar and amp for that factor as well.
I like the control I have with the little pick. It's great for lead work.  I also use it to play rhythm guitar.
But for that it took me to 2 years to adjust to it. Before that I had different picks for lead and rhythm.
I'm at the point now where I can even play the bass with that little pick!
I don't dig deep into the strings, I just hit them with a bit of the end of the pick. That's all that's really needed.
The pick is flexible against the strings and like that.

Well....that's about it.  For a good example, listen to the 2012 Fan Jam DVD's available from Tom Baltaeff.
I thought that the tone I had on "Blue Moon" and "Silver City" is just about as close as I can get to
Bob Bogle's early Ventures Sound.

Jeff G -

Hi Tom, Walt and All Fans of The Ventures.  I'm hopping aboard! 

Jeff G.