Manley VOXBOX - MVB 1996 - 2/2000 and MVBX 6/2000 - 4/2003 - Manual (Page 13)

13
THE EQ & DE-ESSER
The first part of the EQ & De-Esser section is the "EQ INPUT" select switch. The three inputs are;
1) LINE IN - from "Line In" XLR and phone jack - transformer balanced - The signal "splits" to both the
preamp and EQ sections and also to the meter.
2) PRE OP - The Mic Preamplifier and Compressor output. This signal does not pass through a transformer
but the preamplifier may still be affected by the output transformer unless you insert a plug
into the PREAMP OUT phone jack. The Pre O/P can be metered. These first two positions
allow one to compare the LINE IN signal with and without compression and gain.
3) INSERT - This is a line input direct into the EQ. It can be used to "insert" an external device such as
a gate, delay, distortion or even more EQ and compression. It can also be used as a way to
use the VOX BOX as two separate channels. You could use the preamp for vocal and the
EQ for bass. This input is transformer balanced. With no jacks plugged into either the
INSERT XLR or 1/4 inch phone jack there will be no input when switched to this position.
If you were to patch a short mic cable between the PREAMP OUT and INSERT IN, it
w o u l d
add two transformers into the signal path when you switch to "INSERT". Some people like the
"sound" of good transformers - some don't. You judge.
The EQ is based on the MANLEY MID FREQUENCY Equalizer which was based on the PULTEC MEQ.
The original passive circuit was designed by Western Electric to improve the sound of voice through telephone lines.
Pulse Technologies (Pultec) licensed it from Western Electric and Manley was given full permission and "blessing"
from retired Eugene Shenk
who owned the Pultec name at the time David and EveAnna travelled to Teaneck, NJ to
meet him.
For the VOX BOX, we left the original frequencies untouched so that there is still a lot of mid control but we
extended the range of frequencies so that it could hardly be called a mid EQ anymore. It remains a passive EQ meaning
that there is only a capacitor, inductor, rotary switch and conductive plastic potentiometer for each band. There is no
tube in the EQ circuit and there is definately no ICs or transistors. There is a vacuum tube circuit following the EQ &
De-esser which is used to make up gain lost in the passive EQ. The original Mid EQ stopped at 200 Hz in the lows
- we added 6 more frequencies so that it goes all the way down to 20 Hz now. The LOW PEAK is a boost only control
from 0 to 10 dB with 11"center frequencies" from 20 Hz to 1K (1000 Hz). The MID DIP is cut only also with a 10 dB
range. There are 11 center frequencies from 200 Hz to 7 K (7000 Hz). Similarly the HIGH PEAK is boost only and
has been extended from 5 frequencies to 11 frequencies ranging from 1K5 (1500 Hz) to 20K (20,000 Hz). The BYPASS
switch turns off the EQ function by eliminating the EQ components from the path. Why does each band only give either
cut or boost but not both? It's a Pultec. It's passive. It would require twice as many components or a bunch of op-amps
in the audio path (like most EQs that will be forgotten 3 years from now). We prefer the approach that stands the test
of time to one that compromises sound for the sake of conventional controls. Each approach has advantages.
EQ techniques. The best place to adjust EQ should be mic choice and positioning and possibly room choice.
The better the mic choice the less EQ needed or wanted. This seems to be an effect that travels all the way through to
mastering and broadcast. If you start out right, you will save everybody a lot of correction work - especially yourself.
Some great engineers do not use EQ for the lead vocal track, even at mixing. Most do not EQ to record but some may
do a bit in the monitor path. Why? Quite often vocals are "a work in progress" recorded on different days and different
rooms and they compile phrases from each session.
If you gotta EQ, the place to start is cutting or dipping rather than boosting, according to the best engineers. Before you
boost highs and lows, dip a bit in the mids. It can be less intuitive because most of us want to hear more "something"
than less "something else". Try it sometime.
A note regarding how we've described LA-2A's as fast and LA-3A's as slower. Your experience
may disagree with our generalization. They both used the same opto part # and should be the same. We
believe there was a fair amount of variation over the years and we know of slow and fast versions in both
models. The LA-2A we used to compare was a faster type and the LA-3A was slower. Perhaps a better
description is simply "slow and fast vintageopto" but we did emulate and compare with real vintage units.