Nevertheless, we recommend examining both carton and contents for any signs of damage that may have occurred during shipping. In any case it is a good idea to save the carton and packing materials should you ever need to ship your unit in the future. No special ventilation is required in any installation; other components may be stacked above or below the 4BX provided that they themselves do not get hot. This symbol is intended to alert you of the presence of important operating and maintenance instructions in the literature accompanying the unit. Push this button to turn the 4BX on.

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Nevertheless, we recommend examining both carton and contents for any signs of damage that may have occurred during shipping. In any case it is a good idea to save the carton and packing materials should you ever need to ship your unit in the future. No special ventilation is required in any installation; other components may be stacked above or below the 4BX provided that they themselves do not get hot.

This symbol is intended to alert you of the presence of important operating and maintenance instructions in the literature accompanying the unit. Push this button to turn the 4BX on. It always comes on muted; push the button a second time to unmute the sound. The very first time you do this the sound comes on at - 15 dB; subsequent turn-ons and unmutings make the sound come on at the level it was at before the unit was last turned off, so be careful.

To mute the sound again, as for answering the phone, press the button a third time. The muting is not total: the sound is lowered by some 40 dB from the 0-dB indication, however loud that is. Push this button to turn the 4BX off. The LED above it, which lights up whenever the power is on, will go out. Note: When you turn the 4BX off, it is only re- moved from the signal path; it does not shut down the sound.

This is most likely to happen when using the remote control. Push OFF after the rest of your system is shut down, perhaps, or at least press it cautiously, not casually.

These buttons raise and lower the vol- ume, or gain, of the sound, according to their ar- rows and in the amount shown by the LED column above them. The 0-dB setting in this column is the unity-gain position, where the level of loudness is the same as from your preamp, the 4BX making no increase or decrease.

In this relationship the 4BX always will be lowering the volume from this high level, and the probability of alarming level jumps when the 4BX is put into or taken out of the signal path is reduced. See the discussion of the OPF button. Again, caution is war- ranted with the OFF button. These buttons control, according to their arrows, the amount the 4BX expands the dy- namic range of the sound.

A setting of 1. In the latter case, an input signal with 40 dB of dynamic range will be ex- panded to 56 dB and a signal with 50 dB will go to 70 dB. The maximum expansion, as marked, is 50 percent. HF stands for high frequencies, above approximately 6 kHz; MF is the mid- frequencies, between about Hz and 6 kHz; and LF is the low frequencies, below approximately Hz. The amount of HF expansion can be separately adjusted to suit various kinds of music and different speakers, and to vary the overall expansion "mix"; see Connections: Rear Jacks and Contmls.

When the incoming program signal is above louder than this set level, the4BX expands it upward, making it louder still. When the signal is below softer than this level, the 4BX expands it downward, making it still softer.

And when the signal is exactly at he level set by these buttons, it goes through unexpandod. This may well be startling but, as was the case with hitting the OFF button, it is unlikely to do damage. This upward expansion of attacks adds consid- erable crispness and, well, impact to the sound, and does so musically.

These buttons choose what program you listen to. But be advised that this calls for con- siderable care, for a number of reasons. All cassette decks are readily overloaded by powerful signals; open-reel recorders have an easier time of it. Con- servative recording levels and moderate expansion and impact-restoration settings will help, although conventional mechanical recording-level meters needles cannot respond fast enough to something as quick as impact restoration.

Therefore they must not be pushed thoughtlessly during the recording. This means, among other things, that the loudness level in the room either has to be as you like it for the duration of the selection or has to be controlled by your preamp only. And in many instances it might be a great conven- ience to have an instant remote capability for lower- ing or muting applause, commercials, etc.

For foolproof results, then, we recommend that you do your expansion and impact restoration on playback. Everything else still works. And by extension, naturally, it is n remote volume control for your entire stereo.

At Inst, you can lower or mute the sound in the room without having to get up and go over to your system. The control is not particularly directional, and can operate over a long range 25 Tcct or so. Since it transmits infrared light, furthermore, its signal can be bounced off walls and windows, as necessary. The adjacent LED indicates reception. There are times when too great an off-axis direction of aim or too much distance from the 4BX can result in the loss of remote capability.

Similarly, too much light shining on the front of the 4BX may create an optical interference or "background noise" that the Logi- control must be stronger than in order to get through; if the room lights are too bright, it will fail.

Generally, the Logicontrol will enable you to do what you want with the 4BX at any reasonable distance. The supplied 9-V alkaline battery should last a year or more in typical use; replace it with the same type, i. Right commonly is designated by red cable ends; for some people it helps simply to remember that "red" and "right" start with the same letter. You can use either Tape 1 or Tape 2. Also note that in order for you to use your 4BX in this hookup, your preamp must always be switched on its front panel to the corresponding Tape position Tape 1 or Tape 2, etc.

Note: regarding these two tape-deck hookups, if you have a dbx noise-reduction unit or other signal- processing equipment, see the connection diagram on page Replace a blown fuse with the same type as marked , but if the new fuse blows, have the unit checked. A word about switched and unswilched ac outlets on other components to plug the 4BX into. This control affects the rate speed at which impact restoration decreases. That is, the end of the attack may be made to die more and less quickly.

And these are just the extremes of music. Experi- ment to find what sounds best to you most of the time; the factory setting is just a starting point. The control is easily turned with a small flat-bladed screwdriver, such as often come with phono car- tridges. This control raises and lowers the transition level see the Front Panel discus- sion of the high band only, the band most likely to require changing for different kinds of music and speakers. In a good piece of music, over time, the startling becomes familiar, even as the famil- iar stays startling.

This effect, this freshness, frequently is enhanced by the attack of a note or chord. Many of these transients get clipped off or otherwise dulled and muted anyway during the recording or broadcasting process, because of the compressors and limiters that are customarily employed. Conventional dynamic-range expansion, as we shall see, recovers much of this, yet cannot restore the excitement altogether. So with impact restoration we have tried to bring back some of the heart-stopping, breathtaking quality of live performance.

After you have experimented with dif- ferent amounts of impact restoration for various kinds of music, we think you will agree.

As for dynamic range itself, it may be simply defined as the difference in level between the loudest and the softest sounds in any given musical performance or recording. The figure of 1 dlJ is usually given as he smallesl sonic change delectable by most people, although over a wide spec- trum of music or sound and under controlled conditions, a third of this amount is delectable to many.

Some can tolerate dH-SPL averages which are harmful over time; others leave the room at tlO; the dynamic range of human hearing thus is customarily said to be around dB. Note that the relationships among SPL terms are widely misunderstood and misidenlified.

If the true instantaneous peaks are around dB SPL, then the standard fast readings of maxima are about - and these are often labeled "peaks" even within the audio world, especially in discussions of power-amplifier requirements for reproducing conventionally measured fast maximum SPLs - and the average slow readings level is around or so.

The softest sounds in a performance occur just after the musicians stop play- ing the echo and reverberation of the music dying out in the hall Surprisingly, this reverberance may still be heard even when its level is below the hall s own ambient noise - the ear has a remarkable ability to pick out wanted signals in the presence of a large amount of unwanted noise. Tbe difference, then, is around 90 dB, a useful figure for specifying the dynamic range of live unamplif ied music.

Unfortunately, the two most popular forms of storing recorded music that are currently available - vinyl analog records and audio cassettes - have dynamic ranges much, much less than 90 dB. And even tbe best metal-tape cassettes cannot reach 60 dB on their own without. Clearly, the audio signal must be manipulated in order to fit the dynamic range of live music into the constricted limits of tbe popular storage media. The overall dynamic range is thereby restricted.

I lence. If we want to restore this lost dynamic range in listening to a recording or broadcast, an expander is required. The dbx 4BX does just that — it enables a lis- tener to recover substantial portions of the dynamic range missing on existing conventional recordings and during conventional broadcasts. It works by in- creasing the volume of high-level passages and decreasing the volume of low- level ones, the opposite of the compression and gain riding used to constrict the program in the first place.

Since it splits the audio signal into three bands and processes each separately, the 4BX can expand compressed material without the usual artifacts — audible clues — that tell the listener that processing is taking place. AH of which brings back much of the excitement and involvement of listening to music live. In lowering the characteristic noise levels of tapes, records, and broadcasts and restoring the "punch" of loud moments and the whisper of quiet ones, a 4BX can give new life to old record and tape collections and can make FM broad- casts worth listening to closely.

And used carefully with a dbx tape-noise-reduc- tion system such as the or , a 4BX lets you make copies of records, FM broadcasts, and other tapes that actually sound better than the originals. With all of these capabilities, it probably will become one of the most valued components in your home music system.

Further, turn your volume control all the way down before switching on the 4BX for the first time. The tape deck then goes in the 4BX tape bop. Connect it direclty in one of the tape-monitor loops of the preamp, as shown. Those whose stereos surpass this in complexity should investi- gate the dbx X and X Program-Route Selectors. However, some guidelines might prove useful as you experiment with different program mate- ria] and different signal sources.

Classical music, for example, probably will benefit most from expansion at the lower half left side of the scale. You might want to start at 1. Using much more than this may make a lot of classical music surge unnaturally, for usually it has not been se- verely compressed. Popular music, especially broadcast over FM stations, can use much more expansion much of the time — say, from 1.

Non-stereo-LP sources regardless of the program often are badly constricted in dynamic range. We mentioned pop FM above, and the same frequently is true of video signals, from VCRs, video discs and cassettes, and TV tuners and sta- tion transmissions in the first place. Even classical music in such media usually sounds badly squashed, and a 1.

On the other hand, because noise — rumble, hiss, and such — are reduced expanded downward by an expander, the ampli- fier is being used more efficiently.



Seller assumes all responsibility for this listing. Item specifics Condition: For parts or not working : An item that does not function as intended and is not fully operational. This includes items that are defective in ways that render them difficult to use, items that require service or repair, or items missing essential components. Everything work well except the Tape input. It has lower output than the source input. When using the source input and the tape output, it has the same level as the source output. So I narrow the issue down to the tape input connection.


Dbx manuals

Resume making your offerif the page does not update immediately. Would you like to see your company or site here? Hi, are you still looking for information on the dbX 4BX? Select a valid country. Pacific Stereo Sendust for brains. People who viewed this item also viewed. Before that the unit produced some ghastly music.


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