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Moving Coil Phono Step-Up Kit The problem of getting enough gain to use a moving coil phono cartridge with a preamplifier designed for moving magnet cartridge use without lots of noise is easily solved using a Lundahl MC step-up transformer. These transformers are used by several high-end audio manufacturers for this same purpose. The Basic Kit was profiled and praised by Art Dudley in Stereophile magazine in 2007. There are two levels of the Moving Coil Phono Step-Up Kit available, the Basic and Premium kits. These kits both provide two channels of transformer-based MC Step-Up for stereo reproduction.
Basic MC Phono Step-Up Kit The Basic Kit now employs the new Lundahl LL9226 for improved sound. This transformer is a rethinking of the already very good LL9206, incorporating what was learned in the development of the LL1931. It offers across-the-board better perfomance than its predecessor. The Basic unit can be set up for 14, 20 or 26 dB of gain when equipped with LL9226 transformers. Alternatively, the Basic kit can also be supplied with LL1678 transformers for 18, 24, or 30dB of gain, if you have a particularly low output MC cartridge or low gain phono preamplifier. The gain configuration is achieved by soldering jumpers on the PC board supplied with the kit. Sockets for resistors on the secondary side of each transformer are provided on the PC board so that the user can optimize resistive loading for the best sound. Premium MC Phono Step-Up Kit The Premium Kit is supplied with the new LL1931 MC step-up transformers. These were developed by Lundahl in conjunction with K&K Audio as a higher performance alternative to the LL9206 and LL1678. They use the same amorphous cobalt core material, but are substantially larger. The coils are wound with Cardas "6 nines" high purity copper wire. The design was optimized for low to medium output MC cartridges and the sonic performance with these cartridges is exceptional. The LL1931 provides 18dB and 24 dB step-up capability that is switch selectable. There is also grounding flexibility designed into the kit to allow the best performance with different types of tonearm cabling. Sockets for resistors on the secondary side of each transformer are provided on the PC board so that the user can optimize resistive loading for the best sound. The kit includes connectors, transformers, PC board, wire, hardware, and enclosure. The enclosure is a black powder coated diecast aluminum case that provides exceptional RF shielding. The wire used in the kit is the excellent AG23 silver wire made by DH Labs. The RCA connectors are rhodium plated Cardas units. The enclosure is physically small (5.5" x 2.75" x 1.75", 14cm x 7cm x 4.5cm), so it can be located conveniently. The K&K Audio MC Phono Step-Up Kits are not really "newbie" kits, but can be constructed successfully by anyone with good mechanical skills and some soldering experience who can follow instructions. Included with the kit is a step-by-step instruction manual. K&K Audio stands behind you as you build with telephone/e-mail support. However, if you feel that this kit is beyond your skills/inclination, we offer it assembled to your specifications, as well. Basic Moving Coil Step-Up Kit: $300
Single-Ended Triode Phono Preamplifier Kit The family of K&K Audio Phono Preamp Kits accommodates just about all of the LP playing needs that anyone could have at price levels that will appeal to a wide range of users. The kit is equipped to handle moving magnet or moving iron cartridges and, for moving coil cartridges, an input transformer can be added to step-up the lower cartridge output voltage. The circuit was developed to combine the best qualities of tubes and semiconductors and achieve a better result than could be had with either technology alone. The first stage for a moving magnet cartridge consists of a very high transconductance JFET / triode (6N23P/6DJ8/6922/7308) cascode amplifier. This stage is capable of very high gain (about 50dB) with very low noise. An all tube cascode could have been used, but without the simplicity and noise performance of the hybrid approach. The hybrid cascode drives a precision passive RIAA network. This feeds a cascode constant current source loaded triode that is transformer coupled to the outside world using the parallel feed configuration. The lack of DC in the output transformer primary allows the use of a very high quality cobalt amorphous core transformer made by Lundahl Transformers, or, for economy's sake in the Basic Kit, an excellent high nickel core Lundahl transformer. Because the output is transformer coupled, both balanced (XLR) and unbalanced (RCA) connections can be used, achieving the same excellent sound. The power supply is a robust choke-loaded design. There are two levels of Phono Preamp Kits: Basic and "Maxxed-Out". The Basic kit uses high quality parts such as Kimber and Nichicon Muse capacitors, and Mills, Holco and PRP resistors to achieve the best sound in its price class. The Maxxed-Out Kit uses Cardas, Black Gate and Mundorf caps, and Caddock, Mills, Holco, and PRP resistors for the best sound, period! The circuit topologies (and the PC boards) of the two levels are the same, so it is possible to upgrade the Basic Kit to the Maxxed-Out Kit, as resources allow. The K&K Audio Phono Preamp Kits are not "newbie" kits, but can be constructed successfully by anyone with good mechanical skills and some soldering experience who can tell the difference between a resistor, a diode, and a capacitor, and can follow instructions. Included with the kit is a 20+ page instruction manual and a CD-ROM with pictures illustrating various steps in the process. K&K Audio stands behind you as you build with telephone/e-mail support, and, if necessary, will finish/troubleshoot a complete kit for a modest time-based fee. You have the option of purchasing either Main Board Kits to which you must add power supply magnetics, switches, connectors, and an enclosure; or Complete Kits, which include all of the parts necessary for a complete phono preamplifier, except the solder, tools, and the time to assemble it. Furthermore, you can add options to either kit to enhance its usefulness in your music system. Mono/Stereo switching and stereo Volume controls are available as options on both versions. Either complete kit is available with a matte black powder coated front panel or a metallic silver powder coated front panel and knob(s) to match. The specifications for the two levels are:
See the K&K Audio Phono Preamp Kit schematics: Basic Kits Main Board Kit 
All of the parts (except power supply magnetics, switches, connectors, MC input components, hardware, and an enclosure) are included, as well as detailed assembly instructions and a CD full of assembly pictures, to build a 35/41dB gain moving magnet phono preamplifier circuit You simply need to supply 220-0-220VAC (40mA), 10-12VAC (1A) and a minimum 10H (40mA) choke to get this going. All of the other power supply components are on the Main Board and are included in the Main Board Kit. The kit features:
Basic Main Board Kit: $449 Complete Kit The Complete Kit contains every part for building a high-end phono preamplifier comparable to commercial units costing several times the price. In addition to the features mentioned above, the Basic Complete Kit includes:
Basic Complete Kit: $899
Basic Kit Options There are five options for the Basic Phono Preamp Kit that improve its flexibility and/or sound. These options may be installed at the time of assembly or added later. Maxxed-Out Kits Main Board Kit The kit features: 
All of the parts (except power supply magnetics, switches, connectors, MC input components, and an enclosure) are included, as well as detailed assembly instructions and a CD full of assembly pictures, to build a 37/43dB gain moving magnet phono preamplifier circuit. Maxxed-Out Main Board Kit: $799 Complete Kit The Complete Kit contains every part for building a high-end phono preamplifier comparable to the best on the market. In addition to the features mentioned above, the Maxxed-Out Complete Kit includes:
Maxxed-Out Complete Kit: $1899
Options There are several options for the Maxxed-Out Complete Kit that can be easily installed at the time of building the unit. For you mono Beatles LP fanatics, we offer a front panel Stereo/Mono switch. We use a very high quality Seiden switch (as we do for the Polarity/Mute switch) to combine the left and right channels to derive a mono signal from a stereo cartridge output. The output impedance of the K&K Audio SE Phono Preamplifier is low enough to drive a volume control directly, thereby facilitating phono-only systems without the need for a line stage preamp. This is a shunt-type volume control that puts two fixed, low value Caddock resistors in the signal path, preserving the balanced/unbalanced output versatility. The variable shunt element is custom constructed from a 23 position Seiden switch and discrete surface mount Vishay metal film resistors. Only one resistor is present as a shunt element at each volume control setting in each channel. If you want the ultimate in MC cartridge performance, I recommend the new Lundahl LL1931 designed by Lundahl to my performance specifications. It takes the MC performance of the Maxxed-Out Phono Kit into the sonic realm of the truly unaffordable phono stages and you get switchable (versus soldered jumpers) MC gain in the bargain! Lastly, my personal favorite among the parafeed coupling capacitors I've auditioned to date is the Cardas 4.7uF 600v capacitor. These are not used as a standard part in the kit due to the significant added cost and the close performance of the less expensive Mundorf Silver/Gold capacitor. But if you must... In the same vein runs the Tantalum resistor upgrade. These resistors remove a small, but significant amount of veiling that affects your ability to believe that you are hearing the real thing rather than a recording. Stereo/Mono Switch Option: add $100 Volume Control Option: add $225 LL1931 MC Input Upgrade: add $250 Cardas Parafeed Capacitor Upgrade: add $200 Audio Note Tantalum Resistor Upgrade: add $175 Cardas Quad Eutectic Solder (lead, tin, copper, silver), 100gm roll: $13 | ||||||||||||||||||||||||||||||||||||
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