Facebook Twitter

Scott Liebers Labs - Op Amps and Outboard Gear. SL-2520 - Two versions of the SL-2520 were designed as replacement opamps for vintage console restoration.

Scott Liebers Labs - Op Amps and Outboard Gear.

The vintage or “red dot” version is built to match the Huntington and Melville NY opamps from the 70’s. The clean, or “blue dot” version, is made to sound like the newer 2520 opamps. The original intent for making two versions was to use the colored vintage opamps, in console mic pres, and the cleaner versions in the summing amps of vintage consoles. Since then, many SL-2520’s have found their way into numerous DIY projects, EQ’s and even newer Legacy consoles. A great number of SL-2520’s are in use everyday in major market studio consoles including Nashville and New York. Some customers have mixed 2 clean channels and 2 colored channels in multiple channel mic-pre’s to take advantage of different sonic characteristics within the same circuitry of a mic pre.

“I chose Scott's amplifiers for our API console because they are indistinguishable from the vintage originals. Richard McLaurin. Eden Microphone Preamplifier. This is the Eden Microphone Preamplifier from Expat Audio.

Eden Microphone Preamplifier

It comes are a completed module that only needs to be hooked up. In fact, all it needs is power, input, output and a gain setting resistor. It's assembled and tested here in Texas, USA. Performance It has flat THD+N at 30dB of gain as low as 0.003%, all the way to 30kHz (higher I believe - but the audio test kit isn't quite up to it). At 60dB of gain (max setting) the THD+N is still very impressive at 0.04%. Documentation Users Guide: Available for download here: Expat Audio Eden Mic Pre PG2.0 Users Guide Floorplan: (used for drilling the holes in the right places in your case) available for download here: Eden System Footprints 4ch 1U Builders Presentation: Download PDF Kit list for Mouser & Amazon: Download Excel File Front Panel Express File with template for 3 button controller: Download FPD File Audio Clips Acoustic Guitars really do well with an Eden! Rather nice vocal too I think.

User Feedback: "So far I am VERY impressed. How to make custom resistors. How to make custom resistors.

How to make custom resistors

Or individually hand trimmed by frictive attrition (tm) It is not generally known that you can customize a resistor fairly easily. The technique was taught to me by my late farther. An electronics technician in defence research. A recipe that's been in our family for generations. :) Simply put. First some History: My Farther use to work at a defence research place called WRE back in the 50s. Back in the 50s and early 60s large 10% tolerance carbon film resistors were the norm. All this meant that bulky component like trim pots were out of the question mostly.

The resistor it self: A carbon resistor is a carbon based resistive material. How to Customize a Resistor: Assuming you have a standard carbon film resistor at hand, place it between two alligator clips on your multi meter probes thus. Then with a small needle file, file through the coating on the outside of the resistor till you reach the resistive material inside.

Anyway it's that simple. The Philbrick Archive. Deciphering Electrical Characteristics in an Op Amp Datasheet. The Operational Amplifier (Op Amp) is often the key analog gain block in acquiring and scaling real world signals in any data acquisition system.

Deciphering Electrical Characteristics in an Op Amp Datasheet

To predict system accuracy when using op amps it is important to understand the op amp data sheet and how individual specifications affect both the DC and AC transfer accuracy through the op amp. Both DC and AC limitations will be discussed in detail. With this knowledge any engineer can design with op amps right the first time. Sboa054.pdf (application/pdf Object)

Sboa059.pdf (application/pdf Object) Sboa067.pdf (application/pdf Object) Opamp Test and Design Board. Opamp Design and Test BoardRod Elliott (ESP) Introduction Opamps are wonderful little building blocks, but quickly building a test circuit is a real pain.

Opamp Test and Design Board

Most people will use a "breadboard", one of those plastic blocks with holes and connections, but I have found them to be a complete pain in the backside. After a while the contacts expand, wires fall out, and you can't actually see what you are doing anyway. One small slip, and the opamp is consigned to the dustbin. This project is basically what I use for a quick prototype, or for just mucking about with an idea. With four opamps to experiment with, even quite complex circuits can be made. Description For this project, two low-cost dual opamps are used. The layout of the top of the board is shown in Figure 1, and the opamp symbols are simply drawn on the top (non copper side) using a fine felt-tip pen. Figure 1 - The Board Top Layout Figure 2 - The Hacksaw Blade Copper Cutter Figure 3 - Copper Cutting Plan Figure 4 - Mounting The Opamps.

OA10 Discrete Op-amp. Hairball Audio, LLC - DIY JE-990 Discrete Operational Amplifier. One of the key features of the Lola Microphone Preamplifier is the inclusion of two 990 op-amps. Deane Jensen’s now famous JE-990 paper describing the design, testing, and theory behind a powerful ultra low noise operation amplifier, was first introduced in the February 1980 AES journal. The design started with the LM394 dual super matched transistor as the input device. The LM394 is actually a monolithic device consisting of two pairs of 50 transistors connected in parallel to eliminate random variations in the individual devices.

In addition to being designed for low noise, the JE-990 is a powerful op-amp capable of adequately driving a 75Ω load. Many commercial versions of the 990 design are available for purchase today. The common replacement for the LM394 is the Analog Devices MAT12. Luckily there is another option. The DIY JE-990 with bottom mounted SM2212. Pictured is the result of MNATs hard work and my soldering. Quad Eight CA27 Dual Op Amp « Orphan Audio. JLM Hybird Opamp Kit. [header.htm] JLM Hybrid Opamp JLM Hybrid PCB & full PCB parts kit Parts List The JLM Hybrid is a fet input IC opamp with high current output drive transistors.

JLM Hybird Opamp Kit

It can have the output transistors set to run in Class A/B or Class A Mode. It also has on board DC Servo that can be enabled by soldering two solder pads together under the PCB. Can be used in precision Mic pres, EQ gyrators, virtual earth summing stages, headphone amps, balanced in receivers and output drivers. JLM Hybrid opamp circuit PDF Specifications 1.1" x 1.1" PCB THD = 0.008% Min Load = 50ohm Maximum power rails = +/-24vdc Idle Current in class A/B = 10to 12mA Idle Current in class A = 25mA to 30mA.

MCI 2002 Opamp - NEW: SystemsStore.com. How transistor works, an alternate viewpoint. Voltage-driven charge-flows First of all, you must abandon the idea that current travels in transistors or flows inside of wires.

how transistor works, an alternate viewpoint

Yes, you heard me right. Current does not flow. Electric current never flows, since an electric current is not a stuff. Electric current is a flow of something else. Since a current is a flow of charge, the common expression "flow of current" should be avoided, since literally it means "flow of flow of charge So what flows inside of wires?

The stuff that moves within wires is not named Electric Current. Second: the charges found within conductors do not push themselves along, but instead they're pushed by "potential difference;" they're pushed by the voltage-fields within the conductive material. Third: have you discovered the big 'secret' of visualizing electric circuits? Wires and silicon ...both behave like pre-filled water pipes or water tanks. The truth will set you free ...but first it will piss you off! Brief review: See what's happening here? Also: R. The OP-AMP. Before we describe anything technical, let's see one in action.


An op-amp can be connected to a single voltage rail (called UNIPOLAR SUPPLY - 0v to Vcc) or a dual voltage rail (called BIPOLAR SUPPLY +/-Vcc). When connected to a single voltage rail, the output can go from 0v to approx full rail voltage. The OP-AMP has two inputs. A "+" input for non-inverting and "–" for inverting. When the "+" input is a few millivolts higher than the "–" input, the output goes HIGH. If the "–" input sits at half rail voltage via two equal-value resistors, the "+" input must go above ½V for the output to go HIGH, as shown in the animation below: The "–" input can control the output as shown in the animation below: From the animations above we have shown two things: 1. The OP-AMP can be used as a VOLTAGE FOLLOWER. Note: the output follows the input The OP-AMP in the arrangement above has UNITY GAIN (gain = 1).

We will now show how to obtain GAIN or AMPLIFICATION from an OP-AMP. Go to: P2. Classic Audio Products of Illinois. The gar2520 DOA Full Kit Bundle is a full and complete parts kit with everything required to complete the gar2520 Discrete Operational Amplifier build.

Classic Audio Products of Illinois

This board has been designed by Gary Barnett of Barnett Industries. Gary has built upon the reverse engineering work of Peter Lazaro, better know as “Peter Purpose”. This DOA is a nine transistor amplifier modeled after API’s legendary, mid ‘70’s, Studio Systems/Huntington era 2520. The gar2520 sounds absolutely fantastic in our VP25, VP26 and VP312 microphone preamplifiers.

Sonically, it’s hair-splittingly close to a vintage Huntington 2520 which is amazing if you consider the “modern component” phenomenon. Some of the applications the gar2520 DOA can be used for: Microphone Preamplifiers Line or Booster Amplifiers Lossless Combining Amplifiers Balanced Transformerless Amplifiers Equalizers and Compressors Additional features and specs: Industry standard 2520 footprint for plug-in or PC mount connections Low noise, high power output. Scott Liebers Labs - Op Amps and Outboard Gear. Gar2520 Discrete Opamp Kit. Quote: Originally Posted by skydog a couple of questions...will there be a pre built option available?

gar2520 Discrete Opamp Kit

If so how much? Hey skydog, When Gary and I developed our "relationship" regarding his opamps, I agreed that I would never assemble and sell them myself. I do also have Scott's SL-2520 red and blue dot available with the same add to VP26 method. And what do you feel are the sonic differences and similarities between the gar2520 and the sl 2520 red and blue dot versus old/new school api? Well...as usual...this is a slippery slope and very subjective to each individual. The tests we did were again with my preamp which has a custom Ed Anderson EA2622 input trafo and one of Ed's custom EA2623-1 out trafo's. FWIW, UBK is currently in possession of a pair of gar2520's, a pair of SL-2520 red dots, a pair of Peter Lazaro's LAZ25's and I believe someone sent him a pair of Avedis' 1122's also.

I also sent him a pair of my VP26's for his professional opinion. Cheers!