Last
update 10/8/07
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HVTP2: two channel tube micpre/ microphone preamplifier Order with Check or Money Order (Save 3%) Order with PAYPAL
2 Channel Transformer Balanced Class A Vacuum Tube Microphone Preamplifier (micpre) FEATURES / SPECIFICATIONS: GAIN = 62dB 3dB BANDWIDTH = 10Hz to 50KHz or better THD = <1% at 0vu out, +4dBm. INPUT Z, DI = 2.2Mohms (pad out), 200Kohms (pad in, i.e. hi Z line), Mic input 2.5Kohms (pad in or out) CONTROLS = Gain (opt precision step attns), Pad, +48, Phase DESCRIPTION: The HVTP2 kits come complete with everything you need to build the micpre down to the last screw. Controls include: microphone, line, and DI inputs, gain, +48VDC, Pad, and phase per channel. High grade capacitors, 1% metal film resistors, custom audio transformers with large iron/nickel cores on both input and output of each channel (4 in total). Both audio transformers are pc mount, the input is Mu-metal shielded and pin for pin compatible with the industry standard Jensen JT115KE-PC. PC mount audio connectors minimize point-point wiring, and audio proximity to the power supply. The chassis is designed so two will sit side by side in a standard rack shelf (i.e. 4 channels), 2U high with the handle off, and 12.5" deep. We recommend using the 3U because it leaves room for ventilation. Approximate weight 12lbs.
The chassis is made of 16 gauge (very thick) cold rolled, electroplated steel providing a rock solid foundation, and a superior electrical shield compared to aluminum. A center divider which makes seamless contact to the cover and base, provides a tightly shielded compartment for the power supply components. This in concert with the precision regulation of the power, provides an extremely low noise floor. The chassis is powered coated with a two tone finish, and a two color silk screen, making it as attractive as it is indestructible.
The power transformer is a custom designed toroidal transformer which is both efficient, and has very low radiated fields; and can be wired for 120vac or 220/240vac. A true RF filtered power entry module, fuse, and power switch are mounted on the back. Additionally, there are 4 x 0.375" holes that can be used to wire optional rear panel TRS connectors. Everything you see in these pictures, comes in the kit. The only thing you need is a soldering iron, a volt meter, and a few hand tools. The chassis is completely machined/threaded, there is no drilling or mechanical work of any kind required. On the average, it takes about 8-20 hours to build one depending on your skill level. Bottom line is, you spend a couple nights working on it, learning as you go, and in the end save hundreds of dollars. The quality of components in these kits is equal to the micpres we designed and sold for over a decade at $1000/channel, the only real difference is you build it.
All the parts that come with the kit are divided up into separate bags, clearly labeled. Over 25 pages of documentation are included, parts lists, layouts, point-point wire list... Along with the webs support, most people have found building the kits to be pretty straight ahead, but if you have trouble, we are here to help. Though we have tried to simplify the assemble by providing all the parts and detailed documentation, it still requires some elementary understand of electronics, how to use a volt meter, how to solder .... If you are new to DIYing, this may be a bit advanced. The kind of people who should take this on, are people who have built things before, know how to do simple AC/DC measurements, can solder, and can do clean point-point wiring, or have friend that does. At the same time, the last thing I want to do is discourage anyone from trying to learn new skills, and there is no better way to learn than by throwing yourself in the fire. I am just trying to avoid people getting in over their heads, and not being able to complete it. On the flipside, countless people with no experience have built it successfully, and were ecstatic about the end result, and their new found ability. SH |
