Earliest 2000s heads--no bass boost switch

[MikeL]

Anyone have experience with the '68 2000s? Does the lack of a bass boost matter? Or does the bass knob on "10" provide the same low end? Was the tone stack wired differently? When the bass switch on a later model was "off",did that mean that certain filters were shunted(I hope I have my terminology correct)?

[N2000s]

I would guess in general many see the bass boost as unnecessary on the Sunn heads and you should have plenty bass without the boost switch.  Though I have recently been using mine as a way thicken up the low end at lower volumes. On my 2000s the regular bass at 10 does not quite equal what the boost switch will do but a little goes a long way.
On a project recently I was very happy with the EQ set: Highs at 6, Bass at 0, Contour at 7 and bass boost at 1. It's a nice thick boost that worked well for what I was going for.

[EdBass]

Closing the bass boost switch parallels an additional .002uF capacitor with the existing .0075uF capacitor, giving an appreciable low end "bump". I don't use it at gig volumes because I get plenty of thump without it. As N2000s mentions it can thicken things up at lower levels, but I doubt you would really miss it on the '68.
Particularly if you are running it through a big air moving cab like the 2000S cab.

[Soundmasterg]

My 2000S is an early one without the bass boost and I don't miss it. The early 2000S's like this with the Dynaco OT's amplifies cleanly down to 10 Hz, of course the cabinet doesn't go that far though. Like Ed said, at volume you don't really need it.

Greg

[Isaac]

In the 200S, the coupling caps cause a 6dB/octave roll off below 80Hz. The BASS BOOST switch adds in another cap, as EdBass said, lowering that to 40Hz. I have no reason to think that the 2000S circuitry is any different.

Turning the BASS control up will not have the same effect. It will boost frequencies above 80Hz as well as below. In practice, you might not notice much of a difference, especially in a performance situation.

A 10Hz signal would certainly be passed, but would be down at least 18dB, or 12dB if the BASS BOOST is used.

[EdBass]

The 200S works a little different, but the end result is similar. And as Isaac points out, the bass boost doesn't perform the same function as the bass pot. The switch probably should have more accurately been called "ultra low" like it is on some Ampegs. It doesn't really "boost" anything, it just allows lower frequencies through.

It can also suck up headroom when it's engaged, which is another reason as a pretty "clean" player I personally find it less and less useful as the volume level increases.

[loudthud]

I have a very early 1200S head without tremolo and reverb. It had a 0.1uF cap in the circuit where the 2000S had it's bass boost switch. That makes it like the bass boost is on all the time. There were a couple of differences in the 1200S tone stack making it a little different from the 2000S. There aren't many schematics available that show the subtle differences between amps from that era. So... I can't comment on the question here without examining the amp.