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Overview
The JOEMEEK threeQ is like having one channel of a professional record-
ing studio in a small box. It takes a microphone or instrument, amplifies
it, compresses and equalizes it ready to be recorded. Simple to use yet
extremely powerful, the threeQ will bring out the best in any microphone
or instrument and give the gloss of a professional studio production to all
your performances. As well as recording it will also be found useful for live
work.
Think of the threeQ as four separate items of equipment:
• The Preamplifier
• The JOEMEEK Optical Compressor
• The Meequalizer
• The Fader
Preamplifier
This is the all-important front end to the threeQ. Its job is to accept any
type of microphone, instrument or other source of audio signal, and make
it loud enough; microphones often need rather a lot of amplification, while
guitars, keyboards and CD players need less. Mics need to be connected
to low impedance inputs, while instruments prefer high impedance inputs.
To ensure correct impedance matching, the inputs are split into an XLR
connector for Mics, and a jack “Line” connector for everything else. A switch
on the front panel decides which input connector is active. The LED under-
neath the switch lights to show that the Line input (jack) is selected.
In other words:
Switch out (LED off) = “Mic”
Switch in (LED on) = “Line”
Both Mic and Line inputs are electronically balanced. Note: although
the Line input is not normally used for microphones, it can be suitable
for some high output unbalanced microphones, such as battery pow-
ered Electret types.
The Line Input (jack) is balanced and wired as follows:
Tip: + (hot)
Ring: - (cold)
Sleeve: ground
The Mic Input (XLR) is balanced and wired as follows:
Pin 2: + (hot)
Pin 3: - (cold)
Pin 1: ground
PHANTOM POWER
Most high-quality studio mics are “Phantom powered”, which is to
say they have electronics inside them, which get their power from the
preamp. Most mics require a supply of 48 Volts, so Phantom Power is
often labelled “48V”. There is a switch on the back of the threeQ (next
to the XLR mic connector) to turn this power on or off. A red LED lights
when this power is on. When switching the Phantom Power on, quite
a loud thump may be produced, so it is a good idea to turn down the
Output Gain (or to momentarily select the Line input), when pressing
the switch.
When using dynamic or ribbon mics, do not turn this on. It probably won’t
do any harm but it certainly won’t do any good, so leave it off! Consult the
microphone handbook if you are unsure what kind of mic you have.
There is just one other control, labelled “Input Gain”, which covers a range
of amplification from 10dB to 60dB. In many other preamps the action of the
Gain control is rather uneven, with the 40dB to 60dB range being crammed
into the last 1/6th of a turn. All Joemeek preamps use a specially designed
control that ensures smooth operation over the whole range of rotation. The
(0) symbol next to the 25dB mark, means unity gain, or 0dB, for a signal
in the Line input. Hence for Line inputs the range of gain adjustment either
side of this mark, is +35dB, -15dB.
The PEAK LED lights 6dB below clipping, so occasional brief flashes are
OK but if it’s on all the time you need to back the Input Gain off!
TECHNICAL STUFF
Very low noise - does it matter? Yes and no, it all depends what you are
doing - what really matters is “signal-to-noise ratio”. All electronics produce
a certain amount of background noise - it’s in the nature of things. Providing
there is only a relatively small amount of noise, the signal will cover it up, or
“mask” it. So providing the signal is much bigger than the noise, you won’t
be aware of the noise. So in other words the “signal-to-noise ratio” needs to
be a big number, ideally such as 80dB or 90dB.
So how do you achieve that in practice? The trick is to keep the microphone
as close to the sound source as possible without overloading it, so as to get
as much signal out of it as possible. Then you set the Gain control to give
only as much gain as is needed to get a decent level into the recorder.
Of course when there is no signal going on, you may hear the background
noise of the electronics. In that case, given the amount of gain in the studio
monitoring system, this noise “floor” should ideally be in the region of
-80dBu or lower, in order for it not to be noticed.
The threeQ microphone preamplifier uses state-of-the-art electronics
and has an equivalent input noise of around -128dBu (with 150ohm
input load). Despite all the hyperbolae and obfuscation, the theoretical best
possible performance for silicon-based electronics is about -132dBu.
So the preamplifier design used in the threeQ and all other NextGen
Joemeek products approaches this limit. To improve significantly on
this would require highly specialised electronics and probably a vat of
liquid Nitrogen to cool it!
The maximum gain available from the preamp is 60dB, in which case
the noise floor will be -68dBu. This is actually quite noisy - if you record
that noise onto a digital recorder and play it back you can definitely
hear it. In practice of course, you do not record and play back “silence”
and the rest of the mix will probably be more than 70dB louder than
this noise and will mask it completely. Even so it is generally a good
idea not to use gains greater than 40dB or 50dB and indeed, it should
rarely be necessary to do so.
Insert Point
This is simply an unbalanced “Send and Return” jack on the rear panel.
It allows you to patch any other pieces of equipment into the signal
path, such as an effects processor or noise gate. To use it you will need
a “Y” lead wired as follows:
Tip: send
Ring: return
Sleeve: ground
When no jack is inserted, the socket is internally linked, or “normalled”,
so that the signal flows uninterrupted. Note that the Insert Point is after
the Preamp but before the Compressor and EQ.
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