Pre-amp interfacing with SWR Bass 350

Well - here's an interesting question. I just
acquired a used SWR Bass 350 head. While the
tone of the amp is good - it's not 'my' tones; the
tones I created with my ADA MB-1 programmable
preamp.

The SWR Bass 350 has no PA input to bypass the
internal preamp. Meaning, my only option is
(apparently) to run the output of the MB-1 preamp
into the preamp stage of the Bass 350 and then
out through the chain....etc.

This does work, but I find that the preamp on the
Bass 350 clips with the gain past about 11 o'clock
and the PA section does the same at 11-12 o'clock.
This is to be expected, given the set up. The
question is (you electronically inclined folks)
that, assuming I am happy with the sound I am
getting now without the Bass 350 amp or preamp
going into clip, is a resistive pad in line with the
connection between the MB-1 and the Bass 350
input the way to go to damp down the input
signal to the preamp section of the Bass 350?

I am stumped to come up with another solution
short of modifying the amp and adding a switch
and jack to disable the Bass 350 preamp and use
the MB-1 direct to the 350 PA section. This could
be done, but I'd rather leave the amp stock as
I am not convinced it's a keeper. Thoughts?

 

If this works, am I correct in assuming that if I
back off the effects blend knob on the 350 that
I can further 'color' the tone by adjusting the
tone controls on the PA section? As opposed
to running it fully clockwise to only get the
sound of the MB-1 preamp output?

Unfortunately due to life (translation: I have a
20 month old daughter and a wife in graduate
school who has an exam Wednesday) I won't
be able to try this until Wednesday night.

I didn't get a manual with the used 350, so I've
been winging it. Thanks.

 

Thanks for everyone's input on this. I have a gig
this Saturday night and am going to put in some
time with the freshly downloaded manual.

I played a gig last Saturday night with the MB-1
just run into the passive input of the Bass 350
and it sounded acceptably good to play the
gig as we keep the stage volume low - but on
a couple of tunes I'd play harder and the thing
would clip - I could hear it clipping without even
looking at the lights and was alternating
adjusting the output of the MB-1 and the
preamp gain and master vol controls on the 350.
While being aware that this wasn't the solution
and I was going to have to think of something
before this coming weekend.

Wednesday night is rehearsal night, so I'll get a
couple of hours to fool with the thing before I
have to get on stage with it on Saturday.

Scott

 

Looking at the SWR Bass 350 manual, I note that
the cosmetics of the amp shown on the front cover
of the manual differ greatly from mine. The one
on the cover is black with silver front trim and
handles. Mine is black, with silver and purple
silkscreening and regular old bolt-on black rack
handles. An earlier version of the 350, I assume?
Anyone know?

Also, I don't see fan venting on the top rear left
cover - mine has that in addition to the left
side venting.

Scott

 

Wednesday night was rehearsal night - so I tried all of this out.

I can indeed run the output of the MB-1 into the
effects receive jack and run only the master volume
control on the Bass 350. However, I'm not getting very
much headroom. This could be that the output
settings on my MB-1 programs are low
but in general I have them cranked. I tried
running the output of the MB-1 to the active
input rather than the passive input and the
signal seems to be less hot (as expected) and
is working better for limiting clipping than the
passive input was at a similar volume.

I think the next thing to try is an above
suggestion of splitting the input of the bass
between the Bass 350's preamp and the MB-1 and
then using the effects blend knob to mix the
two of them. As I do like having my tones from
the MB-1, but being able to color them to suit
different rooms with the amp is vital. Maybe
in a week or two when I've got some time.

Scott

 

Yes - the blend knob was fully clockwise.

No, distortion was not noted. With the master
volume at 3 or 4 o'clock that amp was not too
loud - you could talk in a normal tone of voice
and be heard above the amplifier. Just wasn't
enough volume.

Running the MB-1 through either the passive
or active jacks was way plenty of volume. Much
more than I need, frankly.

What makes you ask?

Scott