Are there reviews of Audible Illusions products?
|Yes, during the past thirty years, there have been over 150 complimentary reviews of our products. *(Please refer to our Reviews Link Page) FAQ
What significant contributions have Audible Illusions products made to the audio industry?
|Over the years we have produced thousands of audio preamplifiers which have given much pleasure to music lovers world-wide. Audible Illusions is proud to have been a pioneer in modern single-ended tube design.
- In the early 1980′s other audio companies still manufactured preamps based on the venerable 12AX7 tube with cascode circuits, cathode followers and negative feedback, etc. We were one of a few companies to completely base our preamp designs on the 6DJ8 dual triode.
- Audible Illusions was also one of the first audio companies to incorporate automatically muting turn-on safety circuits which prohibits a tube preamp’s dc voltage surges from damaging audio circuits in case of AC power failure.
- The first audio company to employ bare, oxygen-free copper traces on our PCB’s with Teflon solder masks. We continue to hand-solder our circuit boards with silver-bearing solder.
- A.I. developed a special “filament-on” soft-start circuit which greatly extends tube life.
- We were one of the first audio companies to design very fast, low-impedance FET regulated power supplies to support our audio designs.
- First to develop a stable, open-loop, no-feedback line stage which significantly improved sonic performance of our
- We were first to parallel tube stages to lower output impedance thus eliminating the need for cathode followers.
- And, one of the first companies to use pure film-foil capacitors in our audio circuitry.
Today we take pleasure in noting that most modern tube preamplifiers are based on the 6DJ8/ 6922 triode and that many of our refinements are now used by other audio manufacturers. FAQ
Why does A.I. manufacture both tube and solid-state equipment?
|It is our belief that, for low-level amplification, tube designs are best. For power amplifiers we feel solid state is superior due to the complexity of various speaker loads. Our primary consideration is that both technologies be faithful to the music. FAQ
|What is the minimum break-in period for A.I. equipment?
|It has become common knowledge that all high-end audio products require a break-in/burn-in period. Audio equipment can sound somewhat harsh and two dimensional until various internal components have broken in.Electrolytic power supply caps and all parts having any insulating material require the most burn-in. Tubes, FETS and transistors also take time.Minimum “break-in” time for our preamps is 3-4 weeks of normal operation. Our preamps still sound excellent “right-out-of-the-box” but the open, multi-dimensional sound these preamps are famous for won’t occur until the complex dialectic structure in our proprietary film capacitors completely forms. After break-in, further sonic improvement continues with additional time and will continue to improve over an extended period.
Our power amplifiers also require a minimum break-in period of 2-3 weeks with continued sonic improvement over a period of time. FAQ
|Should power conditioning or noise filtering equipment be used?
|In recent years there has been considerable development in quality power conditioning and noise filtering devices as audiophiles have discovered the sonic advantage of clean AC power.We understand that good audio designs must be able to reject extraneous noise. Considering that high impedance tube circuitry is susceptible to such noise we design our products in such a way that noise is not superimposed on the amplified musical signal.Generally, we believe that our tube preamplifiers should be plugged directly into a discrete wall socket providing the AC is reasonably clean. However, if excessive residue of DC or other artifacts are floating on the AC line, we then recommend a quality conditioning device.
Most modern, high-current power amplifiers will benefit from quality power conditioning. Very few amplifiers have adequate AC line conditioning and the ones that do are very expensive. FAQ
is ground loop noise?
|When two separate components, i.e.: preamp and amplifier, are plugged into two separate AC circuits a low
frequency hum is generally amplified with the musical signal and is heard through the speakers. This problem is usually solved by plugging both components into the same circuit
or by “floating” the AC ground lead of one component using a “cheater plug”. A more thorough description of this problem, with suggested remedies, can be located on the website of our dealer in the UK: www.walrus.co.uk/tech/tech.htm FAQ
|What Interconnect cables are recommended for use with A.I. equipment?
|Almost all interconnect cables will work with our equipment. However, please understand that all interconnect cables have a sonic identity. Interconnect cables have measurable resistance and capacitance and when you put a resistor and a capacitor together, guess what, you have a tone control! You should keep this fact in mind if you desire to have accurate musical reproduction. Try to keep the resistance and capacitance of your cables at a minimum value for the required length. FAQ
|What’s the difference between balanced and single-ended designs?
|Basically two types of electrical interface between audio components are used to connect audio equipment, single-ended and balanced. Audible Illusions uses both.However, after years of preamplifier and amplifier design and research we have come to the following conclusions. For our tube preamplifier designs we feel the “simpler-is-better” single-ended design approach is best for sensitive low-level amplification. For our more complex solid-state amplifier designs we feel that, in addition to a single-ended input, balanced circuitry is necessary in order to minimize common mode noise.A brief description of these two design styles are:
Single-ended designs use a single conductor cable to transmit the + waveform and a ground- shield conductor to transmit the – waveform. The audio amplification circuit requires only a positive amplification circuit with the negative tied to ground. This circuitry requires less parts but the designer must be careful in executing the circuit with respect to minimizing extraneous noise from being superimposed on the musical waveform.
Balanced audio designs use separate circuitry for both + and – waveform amplification. Thus the interconnect cables must contain separate conductors for both as well as a third ground conductor and an overall shield. The circuitry is more complex and more expensive but we feel necessary in high-level amplification, particularly if the amplifier is interconnected with a long run of cable that might be susceptible to AC line interference or other noise. FAQ
|My audio system doesn’t sound as good as other systems I’ve heard. What can I do?
|The search for audio perfection can be a frustrating experience. Assembling a great system requires more knowledge than money and does take time and patience. Be advised that most of our authorized dealers are very experienced in setting up audio systems and with proper room-tuning. We urge you to work with your dealer and, if you need additional assistance, please feel free to contact our customer service department. We look forward to you having an audio system that reflects your needs and sensibilities. FAQ
|What is the normal delivery time for A.I. equipment from date of purchase?
|All Audible Illusions products are “made to order” and require a minimum of 2-4 weeks for delivery from time of purchase. However, for convenience to their customers, some of our major dealers do maintain limited stock. FAQ
|Additional technical information posted on some of our dealer’s websites.
AUDIBLE ILLUSIONS TUBE PREAMPLIFIERS
|What is the purpose of a preamplifier? If you don’t play records is one really necessary?In order to be able to drive an amplifier properly, there must be some device to switch the various line sources such as CD, tuner, tape etc. However there are other important reasons to use a preamplifier.In recent years various manufacturers of digital audio equipment have strayed from the industry standard of line source equipment having an output of 1 to 1½ Vac. They are now producing their equipment with voltage outputs far in excess of 2 Volts in order to drive amplifiers directly, thus bypassing the preamplifier. Several of these companies are also including passive volume controls and switching functions in their products. We have also evaluated power amplifiers with passive volume controls on their inputs. Unfortunately, most of these controls and switching devices are of poor quality and seriously degrade sonic performance.
Another trend has been to develop outboard, stepped-attenuator volume controls. While some of these controls are manufactured to high standards they are incapable of driving amplifiers of normal input impedance. Also, with low-impedance amplifiers we measure excessive high-frequency roll-off. Another problem is that these passive controls cannot sufficiently attenuate the excessive peak voltages from many of the “hot-output” digital players currently in production. The result is that many amplifier input stages are being badly damaged.
A well-designed audio preamplifier must not only be able to interconnect/switch a sufficient amount of input devices, it must be able to optimally match impedances. Additionally, the preamplifier has to withstand peak input voltages without circuit overload and protect an amplifiers input stages. Another requirement is that it be low in distortion and sonically neutral. Indeed modern, multi-component, audio systems require well-designed preamplifiers. FAQ
|Historically, why have there been so few great sounding preamplifiers?
|In audio design it’s generally considered that a preamplifier is the most difficult to design. Not only must these designs be able to amplify low-level signals, they must do this over a wide frequency range with minimal distortion and resolution of musical detail. Furthermore, if the preamp has a phono stage, the additional complexity of RIAA equalization adds to the problem.Audio designers, like great chefs, all use the same basic ingredients and recipes/designs. Also, most designers have their own interpretation of how their product should sound. Unfortunately, listening to music is a very subjective process and very few audio designers reference their designs to live musical performances. Thus, there are many individual interpretations of audio equipment and it’s hoped that one of these will “catch on” and appeal to a large enough group of audiophiles to make the product financially successful. This design practice has proven to be very risky with hundreds of preamplifier designs fallen by the wayside. FAQ
|What Makes A.I. Preamplifiers so unique?
|Audible Illusions believes in taking a proven audio design and refining it. In researching great audio designs of the past we have determined that, for low-level, amplification single-ended triode designs are the best.Single-ended audio designs have been around for many years. What makes our preamplifier designs so successful is the incorporation of modern technology and specially designed parts into these basic circuit designs.Our designers understand the superior linearity of a quality vacuum tube design. They also believe that these circuits must be kept simple with single gain stages and no error correcting feedback. Add to this ultra-fast, low-impedance power supplies that can supply voltage to meet the demand of complex musical waveforms and you have the beginnings of a great audio preamplifier.
It is also interesting to note that all of our products are completely hand-soldered using a special silver solder and carefully assembled to exacting specifications. For the sake of optimum sonic performance we have discontinued automatic wave-soldering machines. We take great pride in the quality of our circuit board workmanship. FAQ
|Why don’t A.I. preamps have tone controls?
|Our preamplifiers are “purist designs”. We strive to manufacture them to be absolutely faithful to musical reproduction. However, while we realize that the original performance is sometimes altered in the recording process, Audible Illusions will add no further coloration. FAQ
|Absolute Phase. What does it mean?
|An amplified audio signal/sinewave consists of a positive half and a negative half and both should correspond to the positive and negative polarity of the transducer/speaker used to convert the electronic signal to sound waves. If the equipment is connected properly, full fidelity and stereo image specificity will result. If not, the stereo image will be constricted and lack definition.Recording techniques and audio electronic designs differ with respect to absolute phase. In order that the end user be able to interconnect an audio system properly, it is important that manufacturers provide absolute phase information regarding their product. In most cases it’s a simple matter to reverse the wires at each speaker or the phono cartridge.An excellent description of absolute phase can be located in the archives section of Galen Carol Audio, San Antonio, Texas. http://www.gcaudio.com/Archives/absolutepahse.htm FAQ
|Why are A.I. preamps phase inverting?
|Our design philosophy is based on the basic audio truth “the less in the box – the better the sound”.Our exhaustive tests have proven that the addition of phase inversion stages only adds additional circuitry which complicates accurate audio signal amplification.Considering that absolute phase can be maintained by simply “reversing each speaker connection” we feel that phase
inversion circuitry is unnecessary. FAQ
|How do A.I.’s “full-function” phono preamps differ from its line stage preamps?
|Both preamplifier designs use the same basic parts and circuit topography. However, the “full-function” Modulus 3a is a pure dual-mono design which insures maximum separation of circuit componentry thus minimizing channel cross-talk. FAQ
|Will the Modulus phono preamp work with a low-output cartridge?
|Yes, but with reservations. While the preamp’s low noise and overall 58dB of gain is sufficient to amplify many low-output cartridges we feel there is a general loss of dynamics and low bass performance. For low-output M/C cartridges, (.1-.8mV), we recommend our M/C Gold Board option. FAQ
|What phono cartridges are recommended for use with Modulus preamps?
|For years Audible Illusions has gone through considerable effort to poll our dealers, audio reviewers and end users for their opinions as to which phono cartridges operate best with our preamplifiers. Periodically we publish our revised listing which is supplied to dealers and included with every Owner’s Manual. A copy of the current cartridge survey can be downloaded from our Technical Bulletin section. FAQ
|How long will the tubes in my preamp last?
|The Russian “mil-spec” tubes currently installed in our preamplifiers should last 2-3000 hours or 1-2 years of normal use. However, we are aware that tube filaments are very fragile and susceptible to rough handling. For this reason, and not to inconvenience our customers, we include a spare tube with every new preamplifier shipped. FAQ
|When is it time to change a tube?
|Assuming there has been no premature failure or excessive noise you should expect to change your preamp’s set of tubes after 2 years of normal use. When tubes do fail they make crackling sounds or ring excessively. Otherwise you should notice a gradual softening of dynamics and a roll-off of high frequencies. FAQ
|Does the preamps standby mode extend tube life?
|During our previous experience with tube electronics in the recording industry we learned that if the equipment was left on all of the time maximum circuit stability and tube life was greatly extended. Other than breakage, nothing is more damaging to the delicate inner parts of a tube than to apply full current when it is cold.However, minimizing thermal shock by keeping the filaments on is just a partial solution to extended tube life. It’s necessary to address internal gas build-up and possible poisoning of the cathodes.In the early 1980′s we had perfected a circuit that we felt would improve tube life. Then, only by manufacturing hundreds of preamplifiers with and without this special circuit and monitoring tube life were we able to prove that it works. Subsequently, all Modulus preamplifiers mfg. since 1985 have this standby, soft-start circuit. FAQ
|Does removing the top cover from my Modulus preamp improve its sound?
|Be advised that, to insure maximum rejection of RF interference, our preamp chassis are constructed completely of aluminum parts. Removing the top cover would expose the preamps sensitive low-level circuitry to unwanted noise and hum. We also do not want our owners being exposed to dangerous high voltage. Please, do not operate your Modulus with its top cover removed! FAQ
|Is it OK to remove the phono tubes from my preamp if I only use the line stage?
|DO NOT attempt to operate the preamplifier with the phono stage tubes removed! Doing so will result in excess high voltage on the phono stages’ coupling caps and could damage the circuit. Also, removal of the phono tubes will substantially increase the filament voltage on the line stage tubes and will compromise performance and shorten tube life. FAQ
|What are the dimensions of the box and its shipping weight?
|Audible Illusions preamplifiers are packaged with two boxes, an inner and an outer box. The approximate dimensions of the outer shipping box are 17″D x 27″L x 8″H. Shipping weight is 22lbs. FAQ
|Are upgrades available for older Audible Illusions Preamplifiers?
|Audible Illusions no longer modifies/upgrades its older Modulus Series 1, 2 & 3 Preamps due to the fact that special order of parts to retrofit most models causes production delays. However, several of our dealers do sell “factory reconditioned” Modulus 3 and 3a preamps. We now offer a “factory trade-in program”. Please contact our customer service department if interested. FAQ
PREAMPLIFIERS – MANUFACTURING HISTORY
|DUAL MONO Stereo Preamplifier – $895
Tube compliment 1-12AX7, 2-6DJ8 per channel
|MINI MITE I Stereo Preamplifier – $295Tube compliment 1-12AX7, 2-6DJ8
|URANUS I Stereo Preamplifier – $995
Tube compliment 1-12AX7, 2-6DJ8 per channel
|MODULUS Stereo Preamplifier – $395
Relay turn-on circuitry, tube compliment 1-12AX7, 1-6DJ8, 1-12AU7
|URANUS II Stereo Preamplifier – $1,195
Tube compliment 1-12AX7, 1-6DJ8, 1-12AU7 per channel
|MODULUS ONE Stereo Preamplifier – $495
Outboard power transformer, relay turn-on circuitry, tube compliment 3-6DJ8
|MODULUS 2 Stereo Preamplifier – $595
Dual Mono Design, no-feedback line stage, tube compliment 4-6DJ8
|MODULUS 2A Stereo Preamplifier – $695
Upgraded version of Mod 2 w oxygen free copper circuit boards
|MODULUS 2B Stereo Preamplifier – $795Upgraded version of 2A w FET B+ Power Supply
|MODULUS 2C Stereo Preamplifier – $895
Upgraded version of 2B with Tiffany RCA Jacks, some units with stepped attenuator volume
controls, most had Bourns conductive plastic volume pots
|MODULUS 2D Stereo Preamplifier – $995
Upgraded version of 2C
|MODULUS 3 Stereo Preamplifier – $1495-$1695
Completely re-designed. Now with outboard power supply
|L1 LINE STAGE Stereo Preamplifier – $1495-$1995
With Class A Headphone Amplifier
|MODULUS 3A Stereo Preamplifier – $1895-$2495
Preamplifier has undergone yearly upgrades. Now with stepped attenuator volume controls,
lower impedance circuitry and specialized parts, capacitors, etc.
|L2 LINE STAGE Stereo Preamplifier – $2195
With Remote Control, Surround-Sound Bypass Circuitry
|MODULUS 3B Stereo Preamplifier – $3495-$3895
With stepped attenuator volume controls, teflon-coated capacitors, dual-pole relay switching, low impedance circuitry, and optional moving coil phono stage.
|L3 LINE STAGE Stereo Preamplifier – $3695
With remote control, active unity gain circuitry, redesigned motherboard, and improved power supply.
PREAMPLIFIER TUBE REPLACEMENT
How often should my tubes be replaced?
|In the early 1980′s Audible Illusions developed a unique “filament-on circuit” in which preamp tubes would not be subjected to “thermal shock”, a major cause of premature tube failure. In normal use our factory tested tubes should last minimum of two to three thousand hours, aprox.1-2 years, of normal use. FAQ
|How can I tell if a tube is going bad?
|Unless the tube develops premature-excessive “hiss, rumble or crackling sound” the only way to tell is a gradual softening of high frequencies due to normal plate wear. Audible Illusions recommends that, for optimum sonic performance, Modulus tubes should be changed a least every 12-18 months. Our preamplifiers designs are based on reasonably-priced 6922 tubes. Quality pre-tested tubes are available from our dealers in the range of $25-$50. FAQ
|What are microphonic tubes?
|All “factory-supplied” tubes are pre-tested for low-microphonics, (ringing). However, if in normal use of your preamplifier, any vibration causes a high frequency ringing or pinging sound to be heard through your speakers, we suggest you replace the defective tube as soon as possible.Audible Illusions is most aware of the fact that audio tubes are fragile devices and do not take kindly to rough handling, especially in shipping. In the event of a damaged tube and to minimize our customer’s inconvenience, we always include a spare tube with every new preamplifier. FAQ
|Should my preamplifier’s tubes be matched?
|High performance preamplifiers should contain tubes matched for low noise and voltage. The Modulus’ no feedback line stage absolutely must have graded and matched tubes with a recommended voltage tolerance of +/- 5%. *(Please refer to A.I. Technical Bulletin #2 which explains a simple technique for grading and matching tubes) FAQ
|What tubes are recommended for A.I. preamplifiers?
|Current preamplifier owners should refer to their owner’s manual or consult with A.I. Dealers authorized to sell tubes. Additional-related tube data is in our Technical Bulletin #6.Only “mil-spec, low-noise” 6922,
6DJ8, 7308 or European E88CC tubes are recommended for use in Modulus preamplifiers.Previous production Modulus M2, M3, M3a and L1 preamplifiers used Russian 6922 tubes. While quality and sonic performance of these tubes were excellent for several years it is unfortunate that current-production from the Sovtec/Reflector factory does not have the same sonic identity and a high percentage prematurely fail.
Current production Modulus M3a and L2 Preamplifiers use a Russian Military Type 6922 with “Grey Plates” and have excellent sonics and reliability.
Similar tubes which have different technical specs should not be used.
7DJ8 tubes require higher filament voltage and performance is marginal.
6NIP tubes should not be substituted as they require additional filament current and their use will compromise performance. FAQ
|What are “NOS” tubes?
|The audio term “NOS” simply means “New Old Stock”. There are several tube suppliers who purchase tubes, no longer being manufactured, that were considered to be sonically excellent. Unfortunately, many of these tubes are used and do not meet current performance specifications.Be advised that certain older brands of “NOS” tubes should not be used in modern, high-gain, high-performance preamplifiers like a Modulus. Many of these old type 6DJ8, 7308, E88CC tubes have weak insulators and their internal grids are not wound to close tolerance. Thus they have unacceptable microphonics, tube hiss and high distortion. FAQ
|What is “Tube Rolling”?
|To the best of our knowledge, this term was first used by our good friend Roger Modjeski of Ram Labs. Roger truly understands the audiophile’s desire to constantly “tweak” his system and changing various brands of tubes can change the sonic characteristic of a particular piece of audio equipment. We still proudly display our “tube-rollers society button” he gave us back in the mid 1980′s.Swapping one brand of 6DJ8 for another, particularly with our single-ended Modulus preamps, can be quite noticeable. However, the sonic difference one perceives is subjective and many of these tubes do not meet our technical specifications. We recommend you read our technical bulletin #6 for additional information regarding this subject.Additional information regarding audio tubes is published by The Tweak Shop on their website:
www.tweakshop.com/Tube care.html FAQ
AUDIBLE ILLUSIONS AMPLIFIERS
What is the purpose of an amplifier?
|In order to drive a speaker to realistic sound levels a quality power amplifier must be used to boost the low-level signal source with minimal distortion and sonic coloration. FAQ
|Why are A.I. amplifiers now solid state designs?
|Quite simply, tube power amplifiers tend to be problematical and expensive to operate and very few tube amplifiers perform well at frequency extremes.Audible Illusions also believes in pure Class A and High Bias Class AB Amplifier circuits to insure maximum performance linearity. Regrettably there just are no longer any good power tubes being made that can reliably perform at the high plate voltage required by our push-pull tube designs.We also accepted the challenge to manufacture a solid state amplifier that had the midrange dimensionality of tube amplifiers but also have bass control, dynamic contrasts, superior damping factor, low distortion and transparent sound. FAQ
|Why does A.I. use both Bipolar and FET devices in their designs? Aren’t FETS better?
|Audible Illusions employs both Bipolar and FET transistors in its amplifier designs each to optimum effect.High Speed Bipolar transistors are used exclusively in driver and output stages as these devices exhibit superior dynamics and current handling ability.We believe Field Effect Transistors, “FETS”, are best suited for certain low-noise audio applications and MOSFETS best suited for discrete power supply circuits. FAQ
|What is the difference between Class A and Class AB operation?
|Class A amplifiers, either push-pull or single-ended designs, have their idle bias set very high. This insures the output devices are operating in optimum linearity. This high bias also insures minimum distortion. Be advised that many Class A amplifiers run hot due to inadequate heat sink design. The massive heat sinks of Audible Illusions’ amplifiers insure that they only operate “warm-to-the touch”.Class AB amplifiers operate in push-pull mode. This means that, for each complimentary pair of output devices, one device pushes the positive top half of the sine wave while the other device pulls the negative half. Properly designed, there must also be sufficient bias to insure that the amplifier operates at low volume in Class A mode to at least 10% of its rated output .Audible Illusions Class AB amplifiers are also biased to insure that neither complimentary pair of output devices are turned off. This technique eliminates crossover distortion.
An excellent comparison of Class A and Class AB operation is described by our UK dealer, Walrus Audio. www.walrus.co.uk/tech/tech.htm FAQ
|Do A.I. amplifiers run hot?
|Audible Illusions amplifiers run “warm-to-the-touch” due to their high-bias circuitry. However, massive heat sinks and protection circuitry prohibits overheating. FAQ
|How well do A.I. amplifiers handle low-impedance speakers?
|Our amplifiers are “high-current” designs and double their power into lower impedance loads. Another important consideration is their stability into speakers with highly reactive impedance curves. FAQ
|Are A.I. amplifiers “bridged designs”?
|Absolutely Not. Almost all audio speakers have non-linear impedance curves and require a stable power amplifier. Typically, bridged amplifiers lack the current drive and stability necessary to handle complex speaker loads. FAQ
|What is the recommended break-in period?
|Audible Illusions amplifiers require a 2-3 week break-in period. Further refinement to the sound will continue for a considerable time. FAQ
AMPLIFIERS – MANUFACTURING HISTORY
|MINI-MITE II STEREO TUBE AMPLIFIER – 45wpc, Class AB, $695
Tube compliment 1-12AX7, 1-6CG7, 2-EL34 per channel
|M-80 MONO TUBE AMPLIFIER – 80w, Class AB, $995 each
Tube compliment 1-12AX7, 2-6CG7, 4-6550
|S-50 STEREO TUBE AMPLIFIER – 50wpc, Class AB, $995
Successor to Mini-Mite II, amplifier has larger power transformer, 1st voltage amp. and re-styled faceplate. Tube compliment 1-12AT7, 1-6CG7, 2-EL34 per channel
|M-80 MONO TUBE AMPLIFIER – 80w, Class AB1, $1495 each
Successor to previous M-80 with larger transformers, filament supply and re-styled faceplate. Tube compliment 1-12AX7, 2-6CG7, 4-KT88
|S120 STEREO, SOLID STATE AMPLIFIER – 120wpc $1495
A.I.’s first solid state design.
|S120A STEREO SOLID STATE AMPLIFIER – 120wpc $1795
Successor to S120. Amplifier has regulated relay circuitry, larger driver boards with higher speed transistors, re-styled faceplate etc.
|S120B STEREO SOLID STATE AMPLIFIER – 120wpc $2795
Successor to S120A, Redesigned FET driver circuitry, re-styled faceplate
|M150 MONO SOLID STATE AMPLIFIER – 150w, Class A, $7,495 per pairRegulated Relay & Driver Circuitry w Choke Input. Single-ended or balanced inputs.
Product upgrades for older products are no longer available other than normal repair and maintenance for A.I. amplifiers and preamplifiers. Factory Exchange Program is now available for older model Modulus Series 3 and 3a preamplifiers. (Please contact A.I. Customer Service for details)
FACTORY SERVICE-Warranty and Repairs of A.I. Products
Warranty service is performed, free of charge, for parts and labor for all A.I. products for a period of 2 years from date of purchase. *(Please read warranty agreement)
Warranty Period for tubes is 90 days from date of purchase.
Factory Service/Repairs of A.I. products no longer covered by warranty is charged at rate of $85 per hour, (1-hr min.) plus parts and return shipping.
Manuals for “current production” products may be purchased from Audible Illusions for $15 each. Photocopies of anuals for older products are $20 each. Your request and payment should be mailed to Audible Illusions, PO Box 2537, Daytona Beach, FL. 32115.