1. By Sean Fairchild
Active From a Young Age
I have been a huge advocate of onboard preamps
going back almost to the time I began playing, more
than 20 years ago. And I say going almost that far
back simply because the first two basses I had as a
know-nothing teenager happened to be all passive –
and I didn’t yet know that “passive” or “active” were
words you used to talk about
these massive, heavy things,
rather than attitudes or people.
But the next bass I picked
up – which would be the first
for me in many ways (first
real instrument of quality, first
modern design, first 5-string) –
provided me my first experience
with the all-mighty power
and glory of the active circuit.
Suddenly, I could sound however
I liked to, wherever I was
playing! Playing through the
school band’s shoddy old amp?
Still sounded like me. Playing
directly into a patch bay and
recording right into a Tascam
DA-88? Yep, still sounded like
me. Nevermind that I still didn’t
know very much and essentially
dimed every EQ control on
the thing! What I didn’t know
at the time was that my low
impedance output signal was
not being degraded by cable
runs of various length, and the
character of my sound wasn’t
being partially informed by the
impedance of the input stage of
whatever I plugged into next. I went on to experiment
with preamps made by Ibanez, Bartolini, Aguilar,
Audere, MEC, Seymour Duncan, and probably others
I’m forgetting.
Fast forwarding to now; there are really not very
many reasons these days to not have both your
passive and active bases covered with the same
instrument. Most preamps I’ve tried can be bypassed
to go fully passive, with the caveat being that your
pickups are passive and not running through any
type of active buffer on their way to the blend or
volume pot(s). Heck, you can even add a passive tone
control to most any preamp-loaded bass with passive
pickups, so assuming you’re able to find a spot for a
mini switch or replace a standard pot with a push/pull
one, you can have a traditional, fully passive signal
path AND an active one, with all the benefits of both
at the flick of a switch.
Full Control
The Noll TCM 4 XM is the first 4-band, onboard preamp
I’ve had first-hand experience with that allows for
this “having-your-cake-and-eating-it-too” scenario.
In contrast, I’ve also had great experiences with an
Audere Classic 4-band, but due to that product’s
active pickup mixing and grounding scenario (in
which the pickup grounds are separated from the
common ground), it’s not easily doable to have a
switchable, truly passive setup. The Noll TCM 4 XM
does indeed allow for switching to full passive, and
the configuration I opted to go for was: combination
single-shaft passive tone/active treble control, bass
control, and stacked high-mid and low-mid. I opted to
keep the combination MEC volume/blend/DPDT switch
I had already installed to keep all that functionality
with limited cavity space. I installed the system into
my Warwick Streamer Stage II 6-string, being fed by
Delano SBC-6H dual-coil pickups, each of which have a
dedicated series/single/parallel switch. I also decided
to keep the cool rechargeable Fishman Universal
Battery Pack system with USB-charging ability that
came as part of the newly redesigned Warwick/MEC
preamp for 2016. This component simply takes the
place of the battery and provides the same 9-volt
power supply as a battery would; it’s not involved
with the audio path in any way.
Right off the bat, I dug the Noll’s frequency centers.
For a 4-band EQ, they’re very well thought-out. From
lowest to highest, they are: 40Hz, 400Hz, 1.3kHz,
4.2kHz. This means there are a little more than three
octaves between the peak of the bass and low-mid
filters, a little less than two octaves between the
Noll TCM 4
XM 4-Band
Onboard Bass
Preamp
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2. two mids, and a little less than two octaves between
the high-mid and treble. This means the frequency
bands are spread widely enough to avoid too much
interaction with each other, but also to provide just
enough interaction to not sound artificial. The low
frequency is listed as being the same as that of my
old standby, the venerable Aguilar OBP-3. However,
whereas seasoned users of that particular preamp
may be aware that a little boost or cut on that low EQ
filter goes a substantially long way, I found the Noll’s
control to be more even and easier to dial in a useful
amount of bottom (nearly all the way through the
pot’s rotation). That was a recurrent theme with all of
the Noll’s EQ controls.
The Noll’s low-mid is also centered at the same
frequency as one of the Aguilar’s mid options, at
400Hz. While I have grown fond of a slightly lower
center for a low-mid control, I found the Noll’s to
be very effective at cutting out or adding in what
I’ll refer to as “bulk” – basically, the stuff I don’t
want much of when going for a modern tone with
both pickups, or the stuff I sometimes want more
of when using just the bridge pickup. The high-mid
control is perhaps the best-voiced EQ filter on the
preamp, being situated perfectly to either cut out
honk and clank in a bass that has built-in leanings
towards that side of the sonic spectrum, or to add
in a nice amount of attack when using duller strings
or rolled-off tone on the neck pickup. In fact, it is
actually due to the two mid frequency filters of the
Noll TCM 4 XM that I discovered my new-found love
for the series option with the Delano pickups. Cutting
the low-mid generously and the high-mid just a bit,
with both pickups full-on, allowed me to choose a coil
configuration that emphasized the general voicing
I like from the Delano dual-coils, while removing
the excess, fattening mid frequencies that are a
hallmark of that coil configuration, and which I’m
personally not too fond of. The effect was a wonderful
opening-up of the sonic range the pickups and strings
had to offer, with the resonant peak of the pickups
remaining low enough as to not be too harsh in the
upper register. Finally, the treble control, being voiced
well-lower than many other popular 3 or 4-band EQs,
performed exceedingly well at cutting harshness, or
adding both zing and presence.
A note on the combined passive tone/active treble
control: these things are incredible! I would like to
see them adopted much more widely. This is not a
stacked pot, as is the low-mid/high-mid, but rather
a pot with a single shaft to turn, that’s connected to
a dual-ganged pot body (really, two separate pots
Manufacturer: Noll Electronic
Web: http://noll-electronic.de/
Model: TCM 4 XM
Country of Origin: Germany
Stated Input Impedance: >1 MOhm
Stated Output Impedance: <10 KOhm
Stated Input Sensitivity: max. 450mV @ 9V
Stated Output Voltage: max. 4.5V @ 9V
Stated S-N-Ratio: 96dB (1kHz/5Vss)
Bass Control: +/- 15 dB @ 40Hz
Low Midrange Control: +/- 15 dB @ 400Hz
High Midrange Control: +/- 15 dB @ 1.3kHz
Treble Control: +/- 15 dB @ 4.2kHz
Operating Voltage: +9V (+18V optional)
Power Consumption: typ.1.5mA@9V/450hBatt.Life
Dimensions: 45mm x 30mm x16mm
Price (street): $160.16
Sidebar
Navigate to https://www.youtube.com/
watch?v=PBxY8ThTd3E on desktop to watch a fully
annotated video comparing the Noll TCM 4 XM and
Aguilar OBP-3 under nearly identical circumstances.
Fingerstyle and slapping examples are given with
various EQ settings using both preamp
Note: annotations will not display on mobile.
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3. in one housing, like a blend control). The passive tone is fully rolled-off from one
extreme of the rotation and increases to fully on at the center-detented position;
the active treble stays completely neutral and flat during this part of the rotation.
Then, from the center to the other extreme, the passive tone stays full-on while the
active treble control is engaged from flat to fully boosted. This means that you’re
never using the active treble control to cut high frequencies, preferring the passive
tone’s warmth and familiar variable peak and slope to attenuate them, instead. It
also means that you cannot simultaneously roll off the passive tone while boosting
the active treble, but my guess would be that this is an acceptable trade-off for most
players.
Solid Take
The Noll preamp came impeccably pre-wired and uses high-quality MEC and Alpha
potentiometers and flexible, clearly color-coded wire. But a word to the cavity space-
conscious; the module itself is considerably larger than that of the Aguilar OBP-3 or
Delano Sonar. You’ll want to make sure you have room to stow it and that you can
get the cover back on and flush before you begin surgery. I had a brief moment of
panic when I realized that my initial desired installation location wouldn’t work, due
to conflicting with the Fishman battery system mounted to the cavity plate. While
that may not be your specific concern, make sure you’ve got a good spot, before
you get too deep into the project. I found communication with Noll to be quick and
effective during my initial phase of interest in the product, and shipping was very
fast, especially considering that it came directly from Germany. While I prefer the
more gentle slope at which the EQ controls work from their center detents, some
others may not feel comfortable, at first, with needing to turn a knob further than
they’re used to in order to get the same response. But to keep perspective, all the EQ
controls are listed at +/- 15 dB, which compares similarly to other popular preamps.
If you’re in the USA, you may not yet be familiar with the Noll name or be able to
source them from a local retailer as easily as something domestic, but you just might
find that the imported stuff can be the good stuff! Noll has been well-received in
Europe and around the world for quite some time. And while the market for onboard
preamps has grown more diverse with lots of great options to choose from, the
number of companies making 4-band preamps is notably much smaller. With the
Noll being both affordable and highly configurable for your specific needs, I would
definitely recommend trying the TCM 4 XM in your bass of choice. Of course, not every
preamp will work for every bass/set of pickups/preferred strings/player, and tone
is the most subjective thing we can discuss. But you’ll never know if it might help
you discover your new favorite tone until you try it! In the USA, Noll preamps can be
purchased from Best Bass Gear (www.bestbassgear.com).
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