LaChapell Audio | 583s 500-series Tube Mic Preamp

The LaChapell Audio Model 583s is the world’s first vacuum tube preamplifier designed for the 500 series format.

Based on our popular 992EG, the 583s is quickly becoming the next must-have preamp for those looking to add that extra warmth and character to their “lunch box” collection found only within the thermionic realm. Our initial design approach was simple; identify and extract the key design elements of the 992EG that directly contributes to its’ sound signature, and then inject that into the 583s. This, of course, is the amplifier’s input stage, where the lion share of your signal’s quality and character is generated. While the 583s utilizes a more traditional single-ended amplifier configuration, the overall topology of the 583s’ microphone input stage is equal to that of the 992EG; specifically, feedback loop configuration, Jensen JT-115k microphone input transformer, input impedance, capacitance, etc… Together with the CineMag CMOQ nickel alloy output transformer, the 583s also features an ultra clean output stage using premium Burr-Brown & THAT Corporation balanced line drivers.

                       

Another exciting feature on the 583s is easy tube access; allowing you the ability to experiment with vintage premium tubes! The stock tube for the 583s is the JJ ECC803; a great tube with loads of character. But, you might find yourself preferring a vintage Telefunken ECC83 for female vocals or, a 1960’s RCA 12AX7 black plate for acoustic guitar. The point here is to allow you every possible avenue to refine and tailor your signal to be the best for whatever you may be tracking. No other 500 series preamp allows this level of sonic flexibility.

The 583s is also built to be a “good neighbor” to your other 500 series modules. With the exception of the tube access opening, the 583s has an enclosed chassis, which helps direct cooling and prevents any unwanted interference. In operation, the user has individual control over the input and output gain stages via fully variable potentiometers. This, like its’ 992 older brother, provides total flexibility to explore the 583s’ broad sonic pallet. Additional functions include four illuminated NKK toggle switches for 48v, -20db input pad, polarity reverse and input select.

Specifications:

Internal Gain: 0 to >70dB  
THD+N: 0.25% (Variable) 
Frequency Response: 12Hz to 70KHz 
Max Output (1% THD+N): +26dBu 
RMS Noise: -95dBu 
Typical EIN: -120dBu
Input Impedance: 1.5KΩ 
Tube Compliment: 1 x 12AX7/ECC83 

*Stated specifications are typical measurements but subject to change without notice. All measurements taken while driving a 40kohm load with a 1khz source.



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