ETL1 Circuit Kit
The ETL1 is a premium microphone circuit kit designed for electret capsules. Combine this circuit with our TSB2555 medium-diaphragm capsule to build a surprisingly versatile microphone for much less than the cost of a comparable commercial microphone.
We're posting step-by-step videos that illustrate the build process; see our ETL1 Video Series.
About the Audio Circuit
The ETL1 contains the same audio circuit as our acclaimed MP-V57 transformerless circuit kit. Both are based on the Schoeps CMC5, which is probably the most popular microphone circuit in the world. It is a circuit we've been improving and fine-tuning for seven years.
What's the difference between the ETL1 and MP-V57? The ETL1 requires an electret capsule. The MP-V57 requires an externally-polarized capsule (such as our RK series of large-diaphragm capsules).
Unlike most competing offerings, the ETL1 does not compromise the Schoeps design in its topology nor its components. It uses 1% tolerance resistors, low-noise electrolytic capacitors, imported polypropylene signal caps, and NOS transistors -- including an out-of-production JFET that is ideal for this circuit (due to its low capacitance). We manually "bias" every JFET in our shop to ensure that your mic has the highest possible SPL with minimal distortion.
The ETL1 should fit most 150mm-180mm condenser mic bodies, including the CAD GXL2400 and Apex 435. It fits the BM-700 and BM-800 donor mics that we've tried, but we cannot guarantee compatibility with that product due to the low quality and inconsistency of those cheap microphone bodies.
If you'd like to verify fit in your microphone, click the image at right to download the dimensions (as a PDF). Print the document, check that the printed dimensions match your hardcopy, then cut out the paper PCB and hold it against your chassis. Make sure the mounting holes in the PCB line up with the threaded mounting holes in your mic's chassis, as well as verifying that the PCB would physically fit inside the mic body.
See our S-25 Microphone Kit for an all-inclusive option, including a robust mic body, swivel mount, and capsule.