Quad 303 transistors pdf

The arrangement of the triples used in the quad 303 circuit also allowed the small. There has been some discussion about the output transistors on the 303, quad originally used low speed 2n3055h, which have an ft of around 200khz, replacing them with more modern higher ft types runs the risk of making the amp unstable, however the venerable 2n3773 has the same ft to the 2n3055h and works up to 140 volts and can dissipate 150. Service manuals, owners manuals, schematics, diagrams, datasheets, brochures online for free download and free to your amplifier, receiver, tape, cd, tuner, turntable and recorder. As transistor amplifiers go, the output impedance is a relatively high 0. Theory of transistors and other semiconductor devices 1. Just select the manual from the list below, fill in the orderform and you will.

He gave me the price for a replacement, with some comments about credit card usage. If you wish to repair or upgrade your quad 405 or just want to learn more about the 405 and 4052 you can download the quad 405 service data that i have recreated in pdf format also see my quad 405 evolution which is a set of pdf schematics from the second production issue of quads m12333 405 up to some mods also you should read this. After 20 years or so, i finally got around to getting myself a quad 30333 fm3. Quad 303 manual stereo power amplifier hifi engine. Pnp, is exactly the same the only difference being. The 303 was introduced in 1967 and was sold until 1985. The quad 303 quality unit amplifier domestic, was launched in 1967 for domestic use. I hope someone can help a novice trying to rebuild a 303. Around this neck of the woods they are often used as the 2nd amp in a biamp situation with an advent 300, or nad 30207020 as the midbass amp. By repute, this topology, more than other bjt output stages, allows class ab. Quad 33 preamplifier, quad 303 power amplifier hembrow. This page shows the full specifications of the quad 303 amplifier.

Many have noted that the quad 33 is in many ways a solidstate quad 22. The complete designed and connected circuit sometimes the chip manufacturer may denote the first pin by a small indented circle above the first pin of the chip. The first solidstate quad remains a classic of the genre. Head to ebay and check out the quad 303s you can buy. This lot is an instruction manual and acomprehensive schematic manua l in pdf for the quad. The quad 303 amplifier quickly built something of a. The intention of the tests was to investigate claims. The guy said i just need a little work, turns out i needs a lot of work. Of course the design of the 303 is somewhat strange 2 npn power transistors as quasicomplemetary output stage, and of course the unipolar supply voltage that calls for a large electrolytic series capacitor in the output.

Afterward i continue to collect the quad products quad 34, 405. The quad model 33 control or preamplifier and the model 303 power amplifier were the companys first transistor amps. True, it is a single rail design, and therefore relies on an output coupling capacitor. Conduction in metals metals are filled with electrons. Q11 is a common collector and q12 is a common emitter. Whether you use a turntable, cd player or ipod as your main audio source, the upgrade will result in a big improvement in the audio output. Quad 303 rebuild and upgrade start to finish duration. I had the quad 405 amp which i later upgraded to the 4052 with user replaceable circuit boards. Hi, i have a lovely little vintage system that sounds great to me and includes a pioneer pl112d turntable with shure m75ed cart, quad 33 303 amp and mordaunt short pageant speakers. I remember that i have a pair of quad ii from my friend when i was in secondary school. The quad 303 was not quads first transistor amplifier the quad 50 was a push pull transistor design with a multi tapped output transformer aimed at professional users due to its high cost and odd connections an interesting point about the quad50 and the quad303 is that they were intentionally made the same size as the quad ii valve. The quad 303 amplifier was quads first solid state amplifier after the success of the quad 22 valve amp, and was the first power amplifier to use triplets in its output stage, a clever and unique circuit design that makes ultra low distortion possible without destabilising the transistors. Quad amplifierswitch transistor pnp silicon maximum ratings rating symbol value unit.

Transistor triples are employed in an original circuit to provide a completely symmetrical output stage, quiescent current independent of junction temperature and. Quad general purpose transistor npn silicon maximum ratings rating symbol value unit collector. Its connected through the preamp section of a marantz 2330 receiver. Bipolar transistors transistors xist3 introduction bipolar transistors have the following characteristics. Quad 303 is an extremely easy amp to work on and has an engineer friendly layout, the power supply board and amp boards are on hinged links to the chassis, the output transistors are on the finned heatsink at the back, the main power caps are attached to the chassis. All the highend boards for quad 303 and 405 are available again as well as the highend revisio new blog articles. Quad 303 power amplifier power supply repair eevblog. Quad i have owned a quad 33 which i later replaced with a quad 44. The quad 303 is a preamp with multiple features, packed with some handy tone controls. After 20 years or so, i finally got around to getting myself a quad 303 33 fm3.

A very small amount of current flow emitter tobase base. The quad 303 is the first amplifier to have used the triplet output which is a clever, unique circuit design that makes ultralow distortion possible, without. Ultimate amps for the ultimate loudspeaker nbc news. The quad 306 is a high quality stereo power amplifier primarily intended for use in very high quality sound reproducing systems.

The original quad transistor is in italics our preferred alternative is in bold. Quad 303 driverregulator board installation this instruction covers installation of both driver and regulator boards. If you have only purchased the regulator board then after installation only steps 6 to 8 need apply although you can check your original board setup for correct bias and voltages. The quad 303 amplifier was quad s first solid state amplifier after the success of the quad 22 valve amp, and was the first power amplifier to use triplets in its output stage, a clever and unique circuit design that makes ultra low distortion possible without destabilising the transistors.

In the service manuals the following currents are mentioned. Sep 26, 20 a short video of a quad 303 power amplifier that i have for sale on ebay. The four smoothingoutput caps are replaced using our pcb mounted unit. So love its musical performance and tilt control system. The bias is the standing current which passes through the output transistors. The quad 33 preamplifier does not enjoy a continued respect and loyal support that its stablemate the quad 303 power amplifier enjoys. This pair of transistors will buffer the signal from q3s collector, and provide a high gain as the signal goes to the final stage. Hi, ive been lurking on this site for some time and am currently busy rebuilding a really broken quad 303, amongst its numerous problems is a blown 38496 tr105, and after looking on this site i was wondering why you guys recommend using bc461 over 2n5322.

Quad revision discussion forum quad 303 power transistor. Quad 303 restoration with new power transistors and rca. Nov 05, 2017 im a serial hoarder, with a loft full of useful stuff like an ecko 405 line tv they turned the transmitters off in the mid 80s. There are not just bass boost, cut, and treble, but also highfrequency filters that control slope and frequency to enhance the audio output of lowquality sources. Click on the hyperlink to view the datasheet or to buy. Bipolar transistors are a three lead device having an emitter, a collector, and a base lead. Quad 303 replacement transistors this is the complete list. I am listening to old analogue long playing recordings with classical music dating from 1949 to 1979. Everything you need to do a full revision of your 33 yourself. Quad 303, possible improvement archive the art of sound forum.

Ultimate amps for the ultimate loudspeaker net audios quad 33 and 303. The principle of operation of the two transistor types. Due to being a relatively early transistor power amplifier design, from the 1960s, when high power complimentary pnp transistors were not so easy to find, they. Unfollow quad 303 amplifier to stop getting updates on your ebay feed. Mpq7091 mpq70934motorola smallsignal transistors, fets and diodes device datamotorola reserves the right to make changes without further notice to any products herein. Bias current settings in quad 303 and 50e quad produced two vintage transistor power amplifiers with a bias current, the 50e and d variant, and the 303. The quad 303 represents a high point in the early epoch of transistor amplifier design. Now includes low noise transistors for all the boards. It is ideally suitable for driving loudspeakers in the 416 ohm range and will provide an output of up to 45 watts per channel depending upon the load impedance.

These transistors help to form the input differential stage of the amplifier. Npn quad bipolar transistors bjt are available at mouser electronics. I am going to share a repair that i performed on a quad 303 power amplifier. As supplied every board has been set up and calibrated in a standard quad 303. Cs 303 logic design laboratory manual 7 quad 2 input 7400 hex 7404 inverter fig. I have a question regarding the transistors, it currently has, from the top working down, 38494, 38494, 16112, 2n3055 and 2n3055. Quad 303 amplifier restored with the following new parts. Due to slight tolerance differences between different output transistors and transformers across various 303s it is unlikely that anything other than a rough calibration of voltages and quiescent currents will result however when. In one of your older posts it says the advice is to replace the standard power transistors by. Quad launched the 33 preamplifier and 303 stereo power amplifier in 1967 after a typically long gestation period. In 1969this quad amplifier won the council of industrial design award for its good sound quality. In the late 60s their design and looks were startling and their sound. James moir and associates what follows is the result of a series of listening tests commissioned by the acoustical manufacturing company quad.

Sep 15, 2012 quad 303 is an extremely easy amp to work on and has an engineer friendly layout, the power supply board and amp boards are on hinged links to the chassis, the output transistors are on the finned heatsink at the back, the main power caps are attached to the chassis. P517617 lec5, p1 diodes and transistors diodes what do we use diodes for. When an electric field is applied, the electrons move in the direction opposite. The 303 is considered by many to be the best solid state amplifier that quad built particularily if you are driving quad esl 57s. Stepbystep instructions included via email in pdf format. I acquired a non functioning 303 serial no 35545 and am slowly resurrecting it, i hope. Honey badger class ab audio amplifier share pdf files duration. Click on the hyperlink to view the datasheet or to buy the transistor in the dada electronics webshop. Valves versus transistors the resultsof acomparison among three different ampli. This device utilizes emitter ballasting and is extremely stable and capable of withstanding high vswr under rated operating conditions. Hi, i have the 303 in the chain that i use for mastering, so there is no amplification like phono or other preamps between the 303 and the dac. Quad 303 amplifier or quad 33 preamplifier audiophile upgrade and repair a dramatic improvement to your quad amplifier this upgrade is guaranteed to make your quad 303 or 33 units sound better than new. Many of these, typically one or two per atom in the metal, are free to move about throughout the metal. Quad 306 manual stereo power amplifier hifi engine.

The quad 33 303 hifi amplifiers are classic designs. View and download quad 303 service supplement manual online. Quad 303 transistors i finally have a reply from the service manager who had been on leave. Quad 33 303 amplifier preamp owner n service manual.

Quad 303 power amplifier power supply repair page 1. It would normally be used in conjunction with a quad control unit though other signal sources could be accommodated. Apr 16, 2017 hi group, i am going to share a repair that i performed on a quad 303 power amplifier. View and download quad 303 instruction book online. Bipolar transistors are current regulating devices that control the amount of current flowing through them in proportion to the amount of biasing voltage applied to their base terminal acting like a currentcontrolled switch. Would it be possible to say, generally speaking, whether the sound in any way be different.

In the quad service manual it is stated that the dc bias current of the power transistors. Quad 33 preamplifier schematic 451 kb pdf file icon. Im not sure of the exact vintage of the quad amp as i believe they were produced between 1969 and 1982, but is it w. The first transistor power amplifier from the company was not the 303 but actually the professional number 50 in 1966, from which came the 303 and then the ultimate professional version called the 50e, followed by the iconic 405. Firstly, the prepower combination has far too high a gain for modern digital signal sources and this tends to make the quad 33 a noisy partner to its relatively silent poweramplifier companion. Ill swap 5 broken hoovers for 2 of your toilet rolls. Power capacitors, signal caps, signal diodes, complete power board rebuild, power transistors, output. Quad 303 amplifier modified for general purpose lab amp. Calero quad 303 amplifier fully repaired and restored may. Due to being a relatively early transistor power amplifier design, from the 1960s, when high power complimentary pnp transistors were not so easy to find, they were designed to use a triplet circuit instead, with all npn transistors. Note this thread is a compilation of posts originally published in the now defunct blog section a 70s design classic nb. The quad 303 is a two channel power amplifier primarily designed for high quality domestic installations. All three pcbs are stripped down to bare boards and new high performance components are fitted. The figures and curves refer to measurements on either channel, with or without the other channel.