Compatible Line Output Transformers. Compatible Input Transformers - Eisen Audio, LLC. An input transformer is necessary to unbalance the incoming signal and properly interface it with the op amp , noise-free and at the correct impedance. Since you're building a microphone premplifier, you'd pick one of the microphone input transformers from the table below. However, by using different kinds of input transformers it is possible to build a line-level or instrument-level preamplifier instead. The designations R7, C3, and R8 refer to termination components connected across the transformer secondary, as shown in the DIY500 mkII schematic . R8 provides loading , and R7+C3 comprise a zobel network , when necessary. A box containing ------ means leave that component out. A box left blank means we don't have that information yet. When in doubt, leave the component out. The following microphone input transformers mount directly to the DIY500 PCB Please Note : The above listed transformers are stock items, available new.
Compatible Operational Amplifiers - Eisen Audio, LLC. DIY500 mkII Component Values - Eisen Audio, LLC. DIY500 mkII Component Values To turn your DIY500 mkII Minimal Kit into a complete mic preapmp, you'll need to purchase the rest of the components. This means choosing an op amp and transformer combination, purchasing these from their respective vendors, and then purchasing about $5 USD worth of resistors and capacitors from a parts vendor such as Mouser . The descriptions below list these component values and explains how to determine them.
Component designations (e.g. "R2") refer to the DIY500 mkII schematic , and are printed on the PCB surface. - N/A means leave that component out altogether - Short means short circuit, or 0 ohms. Use zero ohm resistors or straight wire, such as clipped resistor legs. - All resistors are 1/4W %1 metal film - Resistor values are written in ohms, e.g. 6k8 = 6.8k = 6800 ohms CONN3, CONN4 = N/A under normal circumstances. CONN5 = For connecting/disconnecting the output transformers secondary loading resistor, R23. C7, C10 = Normally N/A. C3 = Normally N/A. DIY500 Component Table - Eisen Audio, LLC. The DIY500 mkII PCB surface is printed with many white lines and letter+number designations, indicating where to place each component when building your preamp. The following table lists each component and describes its attributes. For a view of these components in circuit, you may examine the DIY500 mkII schematic . For a verbal description of component functions and default values, see the DIY500 mkII Component Explanations page.
Please note that the second column from the left, titled "DIY500v1-4 PCB" lists equivalent component designations for the now discontinued original DIY500 PCB. Legacy DIY500 owners can use this to translate their old designs to the updated DIY500 mkII structure. Key : A = Amplifier, e.g. All content Copyright © 2005 - 2010 Eisen Audio, LLC and/or respective owners. Diy500mkii_schematic2008_web.jpg (JPEG Image, 1337 × 984 pixels) - Scaled (67%) Eisen Audio DIY 500 Circuits / Aermotor Studio. API Clean / Straight forward great sound like BAE 312a / By Jens Avedis 1122 Opamp Cinemag CMMI-8PCA Input Transformer Cinemag CMOQ-2L Output Transformer D1, D2, D3 = short J1 = short J2 = 47 ohms J3 = short J4, J5 = N/A R1, R10, R11 = 10 ohms, 3/4W or 1W %5 R2, R3 = 6k8 ohms R4, R5 = 680 ohms R6 = 150 ohms R7, R17 = N/A R8 = 100k ohms R9 = short R9a = N/A R12 = 10k ohms R13 = 100 ohms R14 = short R15 = N/A R16 = 1k5 ohms C1 = between 10uF and 82uF (anything will work), 63V radial electrolytic C2, C3, C4 = N/A C5, C6 = 100uF 25V radial electrolytic C7 = 100pF 50V or 100V, C0G/NP0 ceramic is ideal C8 = 470uF 6.3V or more radial or axial.
Bipolar/non-polar preferred, otherwise positive lead faces front panel. C9 = 470uF 16V bipolar/non-polar radial electrolytic (or 1000uF if it fits cannot exceed 25mm!) C10 = N/A API Vintage / Warmer sound, huge low end / By Jens SL-2520 "Vintage" Opamp Cinemag CM-75101APC Input Transformer Cinemag CMOQ-2L Output Transformer API 512 Modern / By Jens. Eisen Audio DIY 500 Circuits / Aermotor Studio.
Eisen Audio DIY 500 Circuits / Aermotor Studio. Eisen Audio DIY 500 Circuits / Aermotor Studio. Eisen Audio DIY 500 Circuits / Aermotor Studio. Hairball Audio. Audio Maintenance Limited AML-07-091 - "Breadboard" for API 500 series rack / GDIY 51x Rack.