I. Introduction AOpen has been a pioneer in the motherboard field, bringing solid and award-winning products to the PC community, for many years. These achievements include the first Intel-based 440BX chipset motherboard with a military-grade black PCB and a 24K gold-plated heatsink for overclockers. AOpen was also the first to offer space-grade ultra-high precision components for commercial motherboards, providing overall PC system stability and long-term reliability.
What’s Lacking is true audio from a PC that can rival hi-fi stereo systems Most of today’s motherboards have audio designs that center on the so-called “AC’97” standards that are certainly sufficient to meet the needs of daily business applications. Technology for both sound cards and on-board AC’97 emphasize a SNR or (signal-to-noise ratio) that’s unrivaled by ordinary stereo components that can be purchased from retail electronics chain stores.
Challenges and Creativity – The AX4B-533 Tube Motherboard The challenges that AOpen engineers have encountered in this endeavor are many-fold in terms of providing a faithful music reproduction scheme to be combined with the motherboard – commonly referred to as “On-board”. Our engineers have remained undaunted by those challenges. The design of such a novel concept involves not only digital know-how, but also linear electronics and acoustic know-how.
II. Know more about Tube What is a Vacuum Tube? The tube is basically an electronic valve that controls the flow of electrons. It consists of an envelope (bulb, usually glass) from which most air and other gasses have been removed. Inside this near vacuum are two systems. One is called the heater. This is in the center of the tube and is the portion you will normally see glowing orange (some tubes may have more than one heater).
Jimmy Page strikes the guitar strings on "Stairway to Heaven" and Angus Young of AC/DC's "Back in Black" share one common attribute– It is the vacuum tube that powers their guitars’ souls that express what they want to sound like and what the listener likes to hear. How The Vacuum Tube Works Let’s take a look at the fundamentals of how the vacuum tube works. In a modern vacuum tube, there are four principal elements that work together to make a tube work.
Mechanical Handling Do not bend or force the metal pins coming out of the base of the tube. This could break the vacuum seal and ruin the tube. The same is true of any sharp mechanical shock. You can usually tell if the seal breaks, as the silver deposits that coat the inside of the glass will turn to a white powder.
Technical merits inside AX4B-533 Tube 6922 Tube Specification Nine-pin miniature tubes (Sovtek 6922 in here) have no plastic base. Locate them in their sockets by noting the space where there is no pins. Do not wiggle these tubes excessively, as you might damage the socket or the glass seal. Specification and max ratings (*) Filament Voltage 6.3V Filament Current 365mA Plate Voltage (max) 130V Plate Current (max) 25mA Plate Dissipation (max) 1.
TubeSound Technology Fusion of P-4 and The Grand Old Vacuum Tube The AX4B-533 Tube Motherboard is a fusion of the latest Intel Pentium 4 technology with the century-old vacuum tube for the perfect marriage in audio reproduction. This hot-fusion of technologies over one hundred years apart has merit of imagination that cannot be denied or taken lightly.
PCB True to AOpen’s heralded tradition of unique motherboard design, a black PCB is used for the AX4B-533 Tube. Since the current and voltage of the tube design require more than just a conventional motherboard PCB, the copper trace has been thickened and several quality improvements have been made to ensure long term reliability and performance. Power Capacitor A magical ELNA electrolytic capacitor is coupled for voltage output for tonality that’s unparalleled.
Switching Power supply and DC-DC converter To make 115V DC available from the motherboard or switching power supply for the tube is a daunting task. The geeks at AOpen have tried different ways to tackle this issue, and have adopted the switching power method for lighting-up the tube. A Maxim 668 DC-DC converter is the heart of the tube power supply, supplying ample voltage for the tube to work under optimal conditions for proper music playback.
Amplification Circuitry After studying many classic pre-amplifier circuits, we decided to use a single dual-triode (one tube with stereo channel), as a main amplification device. By complying with many criteria, we also decided to follow a long path in terms of providing the most faithful, yet economical way, of doing the signal amplification – Direct Path. In this design, a straightforward amplification is achieved without numerous coupling devices that could add coloration to the music.
Common-cathode stage, unbypassed cathode: Voltage Gain (Output 1): Av = (mu * ra )/( ra + (mu + 1)*Rk) Input impedance: Rin = Rg Output impedance (Output 1): Rout = [( ra)/(mu + 1)] //Rk Frequency response (Output 1): f1 = 1/(2*pi*Ci*Rg) - highpass breakpoint due to Ci/Rg f2 = 1/(2*pi*Co*(Rout + Rl)) - highpass breakpoint due to Co/Rout/Rl Where: Rg = the grid resistor Rp = the plate resistor Rk = the cathode resistor Rl = the load resistance, or the input resistance of the next stage Ra = the total load
Coupling Capacitors --- MultiCapTM Polypropylene & Aluminum Foil Multiple-Section Capacitors are used throughout the amplification except power supply. Resistors --- Vishay 1% metal film resistors with high purity ceramic substrate, proprietary nickel-chrome alloy element, and stainless steel end caps. Tube Socket A 24K plated ceramic 9-pin tube socket sits on the center of the PCB at a pivotal point. This high-quality audio grade socket will accommodate years of reliable operation.
Testing Methods Frequency Reponses A udio Precision d B r AX 4B -533 Tube (Tube O UT) Frequency R esponse 06/14/02 11:50:52 -10 -10 -12 -12 -14 -14 -16 -16 -18 -18 -20 -20 -22 -22 -24 -24 d B r B A 10 20 50 100 200 500 Hz A-A_FR .
Conclusion Yes, AX4B-533 Tube is not quite a true “Stereophile” C-class recommended group of components. Yet, given its original fusion idea and meticulous journey to fruition, we believe it is Class-A for certain. It is our belief that gamers and music lovers alike will love the AX4B-533 Tube. This unique motherboard requires a personal audition with ears, heart and soul. Anyone who appreciates well-reproduced sound, whatever the venue, will appreciate a system built with this innovative motherboard.
III. Power it up Unpacking your tube & Insertion 1. Please take out the tube carefully from the packing box. 2. Holding the tube, and try not to touch the printed wordings on it as cautiously as you can.
3. Take a good aim on the pinhole, then slowly inserting the tube pins downward into the white basement with balanced strength. Note: Though some of latest version of Windows support “Digital Audio” through IDE bus, however, in order to use Open Jukebox player, which is driven under BIOS, it is a MUST to insert audio cable to CD-IN connector on the motherboard.
4. You may “slightly” swing and press down the tube bilaterally at the same time to make sure that it will be completely inserted.
Tube Audio Card This daughter card is specially designed for better analog/digital audio out put, it’s strongly recommended to connect your speaker to this RCA-output instead of the normal “speaker out” on the back panel of motherboard for better sound quality.
1. Plug the audio cable to the connector on the daughter card, and notice the orientation of the hook. 2. Connect the other end of the cable to the connector on the motherboard, in the same way; you’ll not be able to plug it in with wrong orientation.
3. Connect your device to the jack on the bracket of this daughter card. 3.5mm Line-IN 6.
IV. Let’s make things better Unplugging the tube for replacement Be Careful - IT'S HOT Current tube technology requires high internal operating temperatures. As a result, the glass part of the tube can reach temperatures as high as 250 degrees. Always allow your AX4B-533 Tube to sit switched off for several minutes before you touch the tubes. Incorrect ways of pulling up the tube: 1.
2. Never touching the printed wordings with your fingers: When you pull out the tube, try not to touch the printed wordings with your fingers, because if that’s an earlier-designed tube, the wordings on tube would be easily rubbed off after few times touching. 3. Inappropriate pulling angle: Most of the tube basement could be a little bit tight, but remember not to pull them too hard bilaterally, for this could break the vacuum seal and ruin the tube.
Correct sequence of pulling out the tube: 1. Waiting at least 30seconds right after cutting off the power for the fuse and inner glass to cool off a bit. 2. Holding the tube with fingers, trying your best not to touch the printed wordings on tube; Swinging slightly bilaterally, and pulling the tube upward with balanced strength.
3. Pull the tube out of the base, and put it into box with care. Note: To prevent loud noise caused by the large current of the huge capacitor on this motherboard, it is strongly recommended to turn off your power amplifier or speaker first before turning off your computer.
Substitution of tube The following tubes can be used on the AX4B-533 Tube for those of whom looking for different tonal characteristics or just replacing the tube. General speaking, a low output tube such as the 6922 will have about 5,000~6,000 operating hours life span. If you use it 4 hours a day, it will probably last for over 4 years. Of course, many factors also determine the life of a tube including working voltage, temperature, vibration…etc.
Comparison of different tubes Please refer to the reference chart below for 6922/6DJ8 tubes comparison: US code EU code Normal 6DJ8 ECC88 High-end 6922 E88CC Advanced 7308 E188CC Exclusive 8223 E288CC Compatible 7DJ8 PCC88 Unique CCa (unique german code) **The CCa here is the same as E88CC, which is made of special quality and low noise, and selected out among E88CC high-grade tubes, with longevity and less noise.
The sound trend of various manufacturers of 6DJ8/ECC88/6922/E188CC: The statement below is just a reference of the sound trend of various manufacturers. You may seek to the individual pages for their details. 1. German made Siemens: Excellent resolution and stage positioning, however the sound is not as solid and thick as England made tube. If your system lacks in resolution, then this Siemens made will be your first choice. 2. England made Mullard, Phlips, Amperex.
The Height comparison of different tubes: --29--
ECC88 / 6DJ8 type Amperex Bugle Boy ECC88 This is the famous “Bugle Boy” made in Netherlands in the 60’s. Excellent resolution and sound stage positioning. Clean yet silky sounded infatuated many audiophiles around the world. As for the subjective feeling, this tube offers extended solid bass, wide sound stage, and sweet mid and airy high. I would pay for $200 for this tube for its tone and look.
Amperex ECC88 The next generation of Bugle boy in the 70’s. Orange globe logo with big “Made in Holland” print on the glass. Sound quality very similar to the original Bugle Boy. An excellent generation. Hard to find like Bugle Boy.
Philips MiniWatt ECC88 This 1960’s Philips MiniWatt no-fault made in Holland ECC88 offers even better “thickness” compare to the Bugle Boy. A must for you to own. If you find this tube in someone’s garage or at the flea market, don’t barging, just buy it.
E88CC / 6922 type Mullard E88CC This gold-plated pin Mullard E88CC is made by Philips in Holland like its cousins Bugle Boy and Philips MiniWatt. Resolution, solid as rock and thick like Cappuccino’s thick crème that makes you feel so comfortable. Yes, it is also hard to come by tube.
Mullard E88CC An England made Mullard E88CC with shiny gold tone accent. Musically satisfactory one for the pre. Voluptuous tonality with seamless dovetails between mid to high.Its skin-deep beauty make it best to the pre-amp that has an open chassis design.
Siemens E88CC Another solid but not hard bass E88CC with excellent resolution and sound stage positioning. This one also meets German’s best – Mercedes Benz and BMW precision engineering.
AEG E88CC AEG is believed to be the parent company of Telefunken. The original company name is AEG-Telefunken. A wonderful sounded E88CC that’s worth to collect.
Telefunken E88CC This Telefunken E88CC is as same as the AEG one. A work of wonder with total relaxation. Telefunken is Telefunken.
Philips E88CC SQ (6922) Details, details and details. One can hear layers after layers of musical information. Open, airy, a total harmony. If you love chamber or New Age music, this is the one that you can not miss.
E188CC / 7308 Philips E188CC Same SQ series from Holland. (Why Holland makes the best tubes?) When the ivory keys were hit, you can feel the notes approaching your ears with force.
Mullard E188CC England made. Similar with Mullard CV4108, but better than it in the sense of space and condensation. As for its sound stage performance, it fully stretches to surrounding space with smooth flow, excellent resolution, and extended bass and treble as if you could watch the airy flow of flute.
Mullard CV4108 Made in England. Thrilled and impressed it gives us as England Tube always do. Extravagant and clean, plus suitable bass and excellent resolution. Touching people no matter in listening vocal, instrument or piano etc.
Siemens 7308 (American made) Though not made in German, but comes with a very good quality. Marvelous resolution that could easily triumph some modern tubes, like Philips EGG 6DJ8, Sveltana 6N1P, Tesla E88CC, etc.
Sylvania 7308 American made tube, which use the same structure as E188CC, with splendid resolution and C/P rate as well. Worth buy product.
Telefunken E188CC 1960 German made, with golden pins, outstanding sound, less interference to bass, which is considered the best buy product in TFK E88CC/CCa/E188CC series.
E88CC-01 / CCa Mullard CV2493 England made CV2493 is equal to E88CC-01, which produces less interference to bass. CV2493 has always been famous with its charming mid range, long life span, and first-rate quality.
Mullard CV2493 Holland made CV2493 is equal to E88CC-01, which produces less interference to bass. CV2493 has always been famous with its charming mid range, long life span, and first-rate quality.
Telefunken CCa 1. You will never realize how wonderful this TFK CCa can bring you unless you insert and listen realistic sound coming from it. Nothing was expected at the beginning when I changed my Mullard CV4108 with this TFK CCa, however, when I insert it on, the miracle happen! It’s so flawless that no matter from what perspective you pick at, you can find nothing wrong! IF you are still not satisfied with its sound, the only explanation must be your CD or your CD Player.
PCC88 / 7DJ8 Telefunken PCC88 No one could resist the incredible sound of TFK PCC88 once they have experienced it. Based on Anthem pre-Amp, try to replace Siemens E88CC with TFK PCC88, you will be immediately moved by the music. It is full of rhythm that you can actually feel the details and music out of the sound. It is getting difficult to find a TFK E88CC/CCa/E188CC lately, you may try your best to get one to possess remarkable sound of it.
After having read so many tubes introduced above, you might be wondering which one is the best? Furthermore, different people have different views. Everyone will have his/her own different answer in the end. To get excellent performance, the arrangement of the sound and the design of the machine play an important role here. I guess you will be able to choose your preferable one once you have personally heard the sound of them. Telefunken Series, beyond doubts, remains the highest grade in the realm of tube.
Appendix A Useful website for vacuum tubes Useful Information Websites for Vacuum Tubes www.thetubestore.com home.pchome.com.tw/art/allen211/ www.sovtek.com www.jimcom.net/ tube.diyzone.net www.cypress.ne.jp/kouchi/index.htm www.stereophile.com/shownews.cgi?1368 www.audiosite-web.com www.bb.wakwak.com/~s-ito/elec/elec.html www.asahi-net.or.jp/~UP2J-KNST/tube.htm www.thlaudio.com/ www.jade.dti.ne.jp/~yoshiba/ www.audio.idv.tw www.alphapex.co.jp/ www.tnbstore.com.tw/ oldtube.com/ home.pchome.
Appendix B Testing equipment list Music Playback The following equipment is used to test with AX4B-533 Tube as a preamp for testing and QA before shipment: Pre-amplifier for comparison Audio Research LS-1 Audio Research LS-16 Audio Research LS-2 Golden Tube SEP-1 Audio Research LS-7 Sonic Frontiers SFL1-Signature Audio Research LS-15 Power amplifier Audio Research VT50 Jeff Rowland Model 1 Audi Research VT100 PASS X150 Bryston 4BST USHER R0.
CD player Meridian 506.20 Rotel 971 Meridian 508.24 Musical Fidelity A3CD Wadia 301 Philips LHH 100 Pioneer DV-S9 USHER CD-100 Speaker ProAc Response 1SC B & W 602 S2 ProAc Response 1.5 B & W DM303 ProAc Response 2.5 Dynaudio Contour 2.8 ProAc Tablet III Dynaudio Contour 3.
Earphone Audio Technica ATH-W2002 Grado SR80 Speaker cable Kimber kable 8TC (double run) Kimber Kable BiFocal XL ZU Cable Julian CDs Yamamoto Yoshi – Misty - JVC XRCD Groove Note – Jacintha – Here’s to Ben Diane Krall – Look in your eyes Rodgers Hart – Blue Moon Three Blind Mice Christian Lindberg – Songs for Sunset Gary Karr – Audiophile Selections B B de Voeux Ennio Morricone – The Legend Of 1900 Dilber – The Art of Coloratura --53--
Testing Equipment: Special thanks to REALTEK lab for Audio Precision Test. Game Our game experience testing includes the following equipment: AX4B-533 Tube Intel Pentium 4 1.8A GHz AOpen H610-340 cooling fan AOpen 52X CD-ROM Apacer 512MB DDR Seagate 20GB hard drive Panasonic 1.44MB floppy drive AOpen 19” monitor Speaker: AOpen MS-810 Altec Lansing 621 AOpen MS-900 Klipsch ProMedia 2.
Appendix C A Letter for Tube Lovers To: Tube Lovers Sent: June, 29, 2002 From: AOpen Motherboard Team Cc: AX4B-533 Tube Staffs Subject: Letter to Tube Lovers Following a long and challenging road of designing AX4B-533 Tube, we finally present you this fine piece of product and hoping you will like what you see and hear.
steps will assist you to properly set up the system and provide you useful resources when needed. Connection The audio portion of AX4B-533 Tube can be set up in the following ways: a. b. c. Direct connect to PC multimedia speaker 2 channel through tube output stage 2.1 channel through tube output stage 5.1 channel (front left and right through tube output stage and rest of 4 channels through regular AC’97 output stage Direct connect to a headphone through headphone jack (Standard 6.
motherboard. Speaker Selection PC multimedia speakers may not be able to reproduce realistic sound stage as presentation compare to stereo speakers due to its build and costs. Therefore, recommend you to acquire a pair of stereo speaker that the tonality suits you for listening. As for the game’s sound effect, nicely built PC multimedia speakers will get well done as well.
with an RCA-to-mini-phone jack (3.5mm) and serve as source. Please refer to the tube manual page 21. Headphone selection You can use two kinds of headphones ! 6.3mm headphone ! 3.5mm headphone - via a converter to a 3.5mm plug for the lighter and smaller headphone that can be found in many today’s gear such as MP3 player and portable CD player to listen the audio through the AX4B-533 Tube connector via the supplied bracket. We recommend you acquire a pair of good quality headphone with 6.3mm plug.
Accessories Sonic imperfections such as distortion and noise do occurred during any type of music playback even with money-no-object high-end stereo equipment. We are not particularly concerning about the sonic imperfection of AX4B-533 Tube since its technical merit will speak for itself.
! Overclockability with 1MHz stepping frequency adjustment ! Watch Dog Timer to assist overclockers to achieve optimum system configuration with highest overclocking capability ! Dr.
The sweetness of a female vocal will touch your heart and soul when playing by the AX4B-533 Tube. Realistic musical note flows from a wind instrument transpired to your ears with measurable distance. Trust your heart when auditioning AX4B-533 Tube. When playing pc games, you will hear more realistic engine revving of racing cars; swords chopping through the air, punches and kicks have more solid bass and tension of the sound effect.
We do welcome your comments and suggestions on this product and will use it to improve our future product design. Please feel free to contact us. http://english.aopen.com.tw/tech/contact/courage.htm.
