Aphex 204 Aural Exciter 电路图.pdf

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1、aural exciter and optical big bottom Instruction Manual P/N 999-4140 Revision 2 Released 09/01/2001 Manufactured by Aphex Systems Ltd. 11068 Randall St. Sun Valley, CA 91352 USA SYSTEMS Solution Delivery Series Copyright 2001 Aphex Systems Ltd. All rights reserved. Produced by: Donn Werrbach. Creati

2、on tool: Adobe InDesign 1.5. Printed by: Stuart F. Cooper Co., Los Angeles. 204 RadioFans.CN 收音机爱 好者资料库 Aphex Systems Ltd. Model 204Page 2 204 instruction Manual CAUTION: For continued protection against risk of fire, replace only with the same type and rating of fuse. ATTENTION: pour une protection

3、 continue contre les risques dincendie, ne remplacer quavec la mme valeur et mme type de fusible. WARNING: This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection

4、against harm- ful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the operating guide, may cause interference to radio communications. Operation of this e

5、quipment in a residential area is likely to cause interference in which case the user will be required to correct the interference at his own expense. The user is cautioned that changes and modifications made to the equipment without approval of the manu- facturer could void the users authority to o

6、perate this equipment. It is suggested that the user use only shielded and grounded cables to ensure compliance with FCC Rules. | Safety Declarations CUS 59887 Conforms to standards UL60950 and EN60950. RadioFans.CN 收音机爱 好者资料库 Page 3Aphex Systems Ltd. Model 204 204 Aural Exci t er and OPTI CAL Bi g

7、Bottom Copyright 2001 by Aphex Systems, LTD. All rights reserved. All Aphex products are trademarks or registered trademarks of Aphex Systems, LTD. Other brand and product names are trademarks or registered trademarks of their respective holders. A MESSAGE FROM THE PRESIDENT Dear Aphex Customer, We

8、are very pleased to have been able to create the Model 204s unique, powerful processing and deliver it to you in such a cost effective package. Years of research and development, as well as over 20 years of direct experience in the recording, broadcast and PA fields produced the latest refinements o

9、f the Aural Exciter and the development of Optical Big Bottom. There are other devices on the market which claim to do the same things as the Model 204 but the compre- hensive patent protection on our technology simply makes those claims unrealizable. The truth is clearly evident every time a proper

10、 comparison is made. We are happy that you have made the right choice and we are sure that you will be happy with that choice for many years to come. Marvin Caesar Aphex Systems Ltd. Model 204Page 4 204 instruction Manual ATTENTION This instruction manual is intended to be a complete reference on th

11、e Model 204. We encourage you to read it! If you dont, at least peruse the Table of Contents to familiarize yourself with the scope of information available to you. We want you to get the fullest measure of satisfaction from your new Model 204. To that end, this manual was written to anticipate most

12、 of the questions and problems users are likely to encounter. Please let the manual serve as your guide and mentor. You may find its various sections on wiring and connecting especially helpful. Page 5Aphex Systems Ltd. Model 204 204 Aural Exci t er and OPTI CAL Bi g Bottom 1.0 QUICK START With Big

13、Bottom 1.1 Simple Hook-up and Settings . 2.0 INTRODUCTION 2.1 The Aural Exciter Legacy . 2.2 The Aural Exciter and Big Bottom Technologies Explained . 2.3 Unpacking and Inspecting . 2.4 Simplified Block Diagram . 3.0 INSTALLATION AND INTERFACING 3.1 Installation . 3.2 Rear Panel View . 3.3 AC Line C

14、onnection . 3.4 Input Connectors . 3.5 Output Connections . 3.6 Nominal Operating Level Selector Switch . 3.7 Wiring Diagrams . 4.0 CONTROLS AND INDICATORS 4.1 Front Panel View . 4.2 Big Bottom Tune Control . 4.3 Big Bottom Drive Control Input (To) - connect the ground and the negative contacts to t

15、he cable shield, connect the positive contact to the positive conductor. Please note that this in fact occurs by default when plugging an unbalanced cable with a 1/4” TS (Tip-Sleeve) phone plug into a TRS (Tip-Ring-Sleeve) phone jack. Note 5: Some electronically balanced output circuits from other m

16、anufacturers exhibit problems when the negative output amplifier is shorted to ground to in order to drive an unbalanced load. The grounded output amplifier pumps current onto the ground which may cause distortion or cause the amplifier to fail. When wiring this type of output be careful to leave th

17、e negative contact unterminated. Note 6: Shield Option: Connect receiving end only. See text preceding Table 2 titled - THE PIN 1 DILEMMA AND HOW IT AFFECTS CABLE SHIELD CONNECTIONS Note 7: Single-Ended, Impedance-Balanced Note 8: It is possible to wire this as an unbalanced interface. To wire unbal

18、anced - use a coax cable with a single conductor and a shield, wire as follows: Output (From) - connect the ground and the negative contacts to the cable shield, connect the positive contact to the positive conductor; Input (To) - connect the ground contact to the cable shield, connect the positive

19、contact to the positive conductor. Aphex Systems Ltd. Model 204Page 32 204 instruction Manual Appendix D: Back To BASS-ICS by Marvin Caesar Think of a sound system with incredible bass. Are you imagining the sound of the bass or are you imagining how the bass would feel? If you are imagining sound,

20、then you are thinking too high in frequency. The bass referred to in this article causes a visceral response. For those who dont relate to feel (and wont eat quiche), these are bass frequencies lower than 80Hz. Therefore, if your interest is speech only, you should read this article only for a furth

21、er under- standing as to why some full range systems will make you want to dance while others will make you want to run. Ask any non-professional to listen to a sound system. Reduce the bass, listen, then reduce the high frequencies, return the bass to flat and listen again. The listener will probab

22、ly decide that listening to the system with attenuated highs is much preferable to listening to the system with attenuated lows. David J. Holman, a friend of ours and a recording engineer and pro- ducer of several platinum albums had this to say about bass: “Bass is the most important thing on a rec

23、ord. Without it you dont have a record. People think bass is just the bass instruments, but it is also the “wood” in an acoustic guitar and the “chest” of a male vocal- ist. With a good low end, a synthesizer sounds rich and expensive. Without a good low end, it just sounds like more digital nonsens

24、e. Maintaining quality bass over a wide dynamic range is made dif- ficult by subjective human hearing response. As shown in the con- stant-loudness curves published by Harvey Fletcher and Wilden Munson, the threshold of hearing at the extreme low frequencies requires approximately 60 dB higher sound

25、 level than the thresh- old of hearing at 1kHz. The hearing curves gradually become fairly flat at listening levels around 90dB-SPL, and remain so above that level. This explains the well-known phenomenon that occurs when play- back level is reduced: the bass seems disappear. Over the years, several

26、 methods have been used to overcome this phenomenon. The most common method has been fixed equaliza- tion. Were all familiar (maybe too familiar) with the disco smile on graphic equalizers: lowest and highest frequencies pushed up, the midrange sagging. By adding a fixed amount of gain on the low en

27、d, this method helps overcome the disappearing bass phenom- enon. The problem caused by this added gain, however, may be more serious than those solved. The principle of superposition is that the motion of electrons in a circuit, or of air around our ears, is single vector sum of all the forces at w

28、ork. Different electrons dont alternate at different fre- quencies; of the electrons in the circuit have the same instanta- neous potential and direction. Figure 1 shows a high frequency riding on a low frequency. Although frequency is not usually shown this way, this is just the way the superpositi

29、on works, in a wire or at our eardrums. Headroom is the range, in decibels, between present operating levels and the crash point, those levels that would damage equip- ment or distort signal. There is no such thing as infinite headroom, electronic or acoustic. If the low frequencies are increased in

30、 level, even though the boosted frequency band never reaches the crash point, the higher frequency peaks are closer to or exceed the crash point. As the boosted frequency band gets lower in frequency, this phe- nomenon gets more pronounced. Imagine adding a direct-current offset into an amplifier, a

31、nd how quickly this change would send the signal into distortion. Subharmonic generators are sometimes used for bass enhancement. These devices read signals in the mid- bass frequency area and synthesize artificial signals an octave below these signals. The use of subharmonic generators also causes

32、an increase in overload problems, with overloads taking place at higher frequencies. Many systems are biamplifted, triamplified or quad-amped. Such systems might avoid the peak overload characteristics of wide- band systems, but adding a fixed amount of low frequency gain or increasing subharmonics

33、can cause overload problems within the bass band(s). Lets ignore overload problems for a moment and look at the sonic effects of these methods. Adding bass boost through equalization or subharmonics might be quite musical when the bass needs the enhancement. These methods, however, have no way of de

34、termin- ing when the bass does not need the enhancement and when it does. If the bass content in the source material is sufficient, adding fixed equalization or subharmonics would surely make the output too bottom-heavy. That brings us to yet another method of bass enhancement: multi- band gain cont

35、rol. The signal is divided into frequency bands, and each band is separately processed through an automatic gain con- trol circuit, which narrows the dynamic range in the band. Whether the outputs of the separate compressors are summed again into a single band or sent directly to amplifiers, this me

36、thod helps keep the bass within a limited time dynamic range, increasing level when the input is low and decreasing level when it is high. The multiband feature reduces spectral intermodulation (one part of the spectrum modulating another), which could be introduced by a simple wide- band device. Al

37、though this method maintains a limited dynamic range, by defi- nition it changes the dynamics of the signal. Thus the sound of the output will depend upon compression ratios, attack and release characteristics and threshold. Depending on how aggressively the signal is being compressed, it may sound

38、totally mashed. Further- more, if there is far greater gain reduction in one band than in others, the total integrity of the entire mix may be thrown out of balance. A NEW SOLUTION What to do? Enter Big Bottom (sideways, if it is a narrow door- way). Aphexs Donn Werrbach, the inventor of the Compell

39、or, the Dom- inator, and several versions of the Aural Exciter, comes from a broadcasting background. In that competitive industry, each sta- tion tries to produce as attention-getting a sound as possible while remaining within legal modulation limits. Given the constraint of extremely limited headr

40、oom, Donn searched for a method that would enhance the low frequencies musically and naturally but without vastly increasing peak output. Appendices Page 33Aphex Systems Ltd. Model 204 204 Aural Exci t er and OPTI CAL Bi g Bottom perception of greater bass energy without substantially increasing pea

41、k output and without sounding muddy. If you already recognize the importance of a good low end and the potential costs (electronic, sonic and financial) of achieving that sound with traditional methods, then Big Bottom may be the solu- tion youre looking for. Appendices He found the answer in time,

42、literally and figuratively. He found that by making a copy of incoming low frequency information, delaying it by a set amount, and adding it back as a constant-level enhancement signal, he was able to achieve a dramatic increase in the perception of the bass without a corresponding increase in peak

43、output. Big Bottom is a relatively simple circuit. The signal is split into two paths. One path goes to the output unmodified, while the other path goes through a frequency shaper, a phase shaper, and finally a dynamics processor. The output of the dynamics processor is then mixed back into the unmo

44、dified signal. The results of the time and amplitude relationship between the unmodified signal and the enhancement signal are a dynamically changing frequency response and longer-duration bass frequencies. Because the output level of the dynamics processor is constant over a wide range of input lev

45、els, it varies as a percentage of the mixed output. At lower input levels, when the bass needs the enhance- ment, the enhanced percentage is reduced. As the input reaches the highest levels, the enhancement signal percentage becomes almost negligible. At high input levels, the bass is still enhanced because of the longer duration of the bass information. The peak o