Summit Audio Model TPA-200B Dual Tube Preamplifier Operating Manual IMPORTANT!: CAREFULLY READ THE ENTIRE INSTRUCTION MANUAL BEFORE HOOKUP OR OPERATION OF THE TPA-200B. WARNING!: HIGH VOLTAGE. THIS UNIT CONTAINS NO USER SERVICEABLE PARTS. SERVICING SHOULD ONLY BE DONE BY QUALIFIED SERVICE PERSONNEL OR FACTORY. DO NOT OPERATE THE TPA-200B WITH THE COVERS REMOVED. Summit Audio 1183 Baltic Suite A Gardnerville, NV 89410 Copyright 1992, 1997, 2003 Summit Audio Inc. ALL RIGHTS RESERVED. Printed in the U.S.A.
Product Introduction The Summit Audio TPA-200B uses vacuum tube and solid state technologies to produce the warm sound associated with tubes with the reliability provided by solid state devices. The TPA-200B is designed to work in a number of different applications with the different types of inputs: a microphone input, line level input, and a front panel Hi-Z input. Input connections are made by using three pin balanced XLR jacks, balanced TRS ¼” jacks, and the front panel unbalanced ¼” jack.
THE CONTROLS 1. LINE/MIC: Selects between the balanced XLR mic input and the balanced ¼” TRS line input on the back of the TPA-200B. 2. PAD: 3. PHASE REVERSE: 4. INPUT GAIN: 5. OUTPUT GAIN: Switches the pad between off, -15dB and –25dB if the output gain of the microphone or line input has too much gain and is overdriving the input of the TPA-200B. This switches the polarity or phase on the microphone input and line input from normal to 180 degrees out of phase.
Line/Mic Switch Polarity (Phase) Reverse Overload (OL) and Overdrive (OD) LEDs -15/-25dB Pad Switch Input Level Hi-Z Input Output Level +48V Phantom Power Switch Power Switch
Use Scenarios and set up Getting a clean microphone signal: Plug the microphone into the mic input on the back of the TPA-200B and set the input switch to mic (and the phantom switch on for condenser mics needing 48v phantom power). Turn the output gain up very high, then slowly turn up the input gain to the desired recording/ monitoring level. Getting tube guitar distortion: Plug the output of the guitar into one of the Hi-Z inputs on the front of the TPA-200B. Turn the output gain low.
Circuit Explanation The TPA-200B is two independent tube preamps with all signal gain occurring in the tube portion of the circuit. The 990 op amp used for the low impedance output stage is made of discrete components and then potted for stability. The line and mic inputs are transformer coupled and are wired for balanced operation. A ¼” unbalanced plug inserted into the Hi-Z input disconnects the line and mic inputs and feeds the grid of the tube directly.
A Word About Tubes The tubes that are used in the TPA-200B are selected to give the best possible performance in the position that they are in on the printed circuit board. Switching them to different positions will cause performance deterioration on the audio path. Replacing them with “gold” or high end tube types may not be desirable. In cases that we have measured, these tubes have shown higher distortion and noise as compared to the tubes we have selected.
Electrical Connections: (This TPA-200B is wired as a pin 2 hot device. Units made before March 1st, 2003 come factory wired with pin 3 hot.
Note on specifications: Summit Audio is uncompromisingly committed to excellence. All of our specifications are made with the latest technology and are UNWEIGHTED measurements. What does this mean? When measurements are “weighted” (e.g. “A” weighted, dB (B), dB C weighted, etc.), the measurement devices are basically EQed or filtered before the measurement is taken. This filtering was developed so that sound pressure level (SPL) measurements can more nearly match human’s non-linear hearing characteristics.
