DaviSound TB-4 Applications Data
Copyright 2001 - 2006 © by DaviSound All Rights Reserved!
The TB-4 is a unique equalizer chain designed specifically for the needs of professional audio, primarily for recording/mixing applications but also well suited for broadcast production and processing as well as multimedia and lab mastering. In short, the equalizer is well suited for ANY high quality audio application where high integrity, musical signal processing is the primary concern.
In fact, the TB-4 is also a very popular Tool Box with working audiophiles and creative home audio enthusiasts! The application is fairly obvious, simple and straightforward but it is covered herewith in some detail.
The new "WG" TB-4 (latest edition - Fall 2006) is now, for the first time, a DUAL channel unit in a single cabinet.
It has three stages, any of which may be switched in or out.
The front panel layout is logical and easy to learn with the first channel located at the top of the control panel and the identical second channel located directly beneath it along the bottom of the panel.
The first TB-4 DaviShaper circuit in the chain, located to the left of the panel is our fixed, four-band "MUSI-Q" equalizer.
This proprietary EQ circuitry has remained in our "arsenal" all these years since so many engineers and musicians swear by it as one of the "most musically useful", four-band equalizers ever conceived!
Now using outboard, EQ controls harnessed to proprietary MP-1 circuit gain blocks, it offers LO and HI "shelving" combined with Lo Mid and Hi Mid "peak and dip" curves at approximately ... 50 HZ, 250 HZ, 2.5 KHZ, and 8 KHZ, +/- 15 dB.
The LO SHELVING CONTROL is designated as 50 HZ which means this is the approximate frequency where the LO control reaches it's maximum effect.
On the other hand, the HI SHELVING CONTROL is designated as 8 KHZ but this is the approximate frequency where this control BEGINS it's shelving action. The curve then swings upwards towards the upper extreme of the audio spectrum where the full 15 dB boost occurs.
This final control has a built-in HI-Frequency rolloff (HI-CUT) that kicks in at the extreme boost settings (beyond THREE O'CLOCK) of the HI SHELVING CONTROL to prevent the boost of frequencies outside the audio band thus aiding stability while preventing inaudible, but existing, ultrasonic "garbage" to be boosted that could otherwise interfere with and corrupt the signal!
So, unlike many other simple shelving equalizers, this one may be used at FULL BOOST without fear of supersonic overload and resulting intermodulation!
The fixed MID BAND controls operate, as already stated, in a PEAK/DIP fashion and are centered with a MEDIUM "Q Factor" very close to the 250 HZ and 2.5KHZ respective frequency ranges.
Many "harsh/hard" low mids have been "softened" with a gentle cut of the " LO MID" control of this equalizer on a quite a few studio recordings over the years!
It is a favorite with bass players and we know of at least a few "name" engineers/producers who will NOT record kickdrum without the low-end section of this equalizer in use (Lo Mid dip/subtle LO Boost) for that "classic" Bass Drum "Sound"!
You will also find that the "HI MID" control is VERY useful for adjusting and balancing vocals and percussive (snare drum etc.) frequencies, especially when used in conjunction with the HI SHELVING control.
The "Musi-Q" section may be silently, and seamlessly, switched in or out as desired by the LED indicated toggle switch located directly adjacent at the left of the stage.
Next, on the panel, and in the signal chain as well, is our old reliable, "Q-Bal Para-Q" semi-parametric equalizer section which provides two, fully sweepable, overlapping bands of equalization, each with a fixed, medium"Q".
The four rotary controls for this stage include hi/lo "Gain", which provide +/- 12 db boost or cut at any frequency in the audio spectrum as selected by the continuously variable hi/lo "Tune" controls.
The "lo" control "sweeps" from just below 30HZ to above 1KHZ. The "hi"control "tunes" from just below 500HZ to just above 18KHZ.
As shown, the layout arrangement is LO TUNE, LO GAIN, HI TUNE, HI GAIN.
Approximate settings for the LO tune control on the far left, would be 50 Hz around 8 O' Clock ... 200 Hz around 10 O' Clock ... 600 Hz at about 2 O' Clock and 3 KHZ at approximately 4 O' Clock.
On the HI tune control, similar 8,10, 2 and 4 O' Clock settings will yield approximately 1 Khz ... 2 Khz ... 4 Khz and 18 KHZ respectively with most of the high frequencies being somewhat tightly grouped between the One and Five O'Clock (4 and 18 KHZ) settings. This is, of course, due to the increasingly shorter wavelengths as the frequencies tune higher.
All in all, The TB-4 "DaviShaper" is one POWERFUL Tool Box which will provide you with the creative means to attain even the most esoteric audio signature!
Each section features an individual, LED indicator which is lighted when that section is switched into the path. This is a VERY useful feature for rapid visual indication during hectic sessions in dim environments.
The final toggle switch at the far right of each channel controls the passive low-cut filter stage which is a classic first order filter beginning action at 100 Hz. This "low rumble" filter is very useful in conjunction with the low shelf boost control allowing some low end shelving while simulataneously attenuating the extreme low end of the spectrum. The "LO-CUT" filter is also an indispensible tool when processing video and multimedia dialog tracks.
The audio signal retains phase integrity throughout the chain regardless of which stages may be switched in or out.
The rear panel is very straightforward with channel inputs and outputs arranged in order when facing the panel with channel one to the left and channel two to the right.
As with all processors providing great leeway in control parameters, this equalizer should be applied with some concern for signal integrity and, particularly, attention should always be given to overall signal GAIN STRUCTURE.
The unit has more headroom than most (approaching +32dBu, at unity, under optimum loading) but, even so, care must be taken so as not to boost frequencies beyond the system ceiling and into distortion! Obviously, with the "Q-Bal" TUNE settings appropriately adjusted, it is possible to boost a given frequency, say 3 KHZ for example, up to +27 dB in conjunction with the "Musi-Q" switched in, were both boost controls operated fully countercclockwise under these conditions.
While this may be possible without ill effect under some conditions and incoming signal levels, it is NOT normally the advisable thing to do and would, of course, represent audibly extreme EQ in any event.
However, the TB-4 is stable enough to allow full boost with both sections switched in under most all conditions! However, there would obviously be little or no real-world professional application which would merit such extreme use.
Further general documentation is included with your unit with the print-outs of "INs and OUTs Of DaviSound Tool Boxes" and "Tool Box Top Tips" which cover connection, interface and general handling and maintenance tips.
Please note rack mounting considerations therein.
As with all Tool Boxes shipped, your unit should arrive with a plastic bag containing the detachable power cord which mates with the socket on the rear panel. Also included in the bag are the publications mentioned above, rack screws and washers, as well as a signed certificate of Title and DaviSound Authenticity. Optional rubber feet may be included for showcase, deskmount, cabinetry.
It is wise to remember that ALL equalizers are, by nature, signal FILTERS and, designed entirely with R/C networks as these are, they are free from the "ringing" and poor transient response associated with the use of inductors in days of old. However, as filters, they are still subject to some minute signal degradation,particularly in terms of phase errors under extreme conditions. Please recognize, however, that DaviSound equalizers and the "DaviShaper" methods meet or exceed any other analog equalizer in use today in this regard. In fact, we venture to say, with the TB-4, signal integrity maintenance is "as good as it gets"!
The TB-4 uses an all discreet power supply for maximum transient handling and headroom. Five individual, high quality German import filter capacitors are employed in a low impedance R/C filter network. Each stage is individually decoupled for optimized custom characteristics and all individual amplifiers are further by-passed with high quality RF grade capacitors at the supply entrance.
The most important consideration in equalizer circuit design itself, is the use of highest quality signal capacitors in the shaping circuitry. DaviSound uses ONLY tested, MATCHED within .1%, mylar film, polystyrene and silver mica capacitors in the "DaviShaper" circuitry!
As with ALL DaviSound Tool Boxes, you may be assured of the ultimate in professional archive signal integrity processing with your TB-4.
Thank you for your choice in owning a DaviSound TB-4 "WG" Tool Box !
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