S-25 Microphone Kit


Microphone Kit

25 in stock

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The S-25 is a professional quality condenser microphone kit. The finished microphone has a Cardioid polar pattern and a switchable -10dB pad (via internal switch). It is sold in DIY kit form, designed for first-time DIY microphone kit builders as well as professional recordists in need of an affordable, high-performance workhorse microphone.


The finished S-25 is extremely versatile, thanks to its neutral tone, high output level, and switchable pad. It works very well on vocals, acoustic guitar, drum overheads, and percussion.

Audio Circuit Details

The S-25 uses our ETL1 circuit kit. It is identical to the audio circuit of our acclaimed MP-V57 and S-series condenser kits. Because it was designed for use with electret capsules, we’ve omitted the DC converter; this eliminates approximately 33% of the parts and one of the circuit boards found in those kits. But the audio performance of the circuit is identical.

The circuit uses 1% tolerance metal film resistors, Wima polypropylene capacitors, low-noise Panasonic electrolytics, and NOS transistors. We manually bias every JFET here in our shop, to ensure that the microphone you build has the maximum possible SPL rating and minimal distortion.

Capsule Details

The Transound TSB-2555 capsule is a medium-diaphragm size, made with 6-micron film. It has a broad, smooth presence boost from 4kHz-12kHz. For those familiar with our RK-47 and RK-12 capsules, the TLM-2555’s curve is sort of a hybrid of these. Its presence boost is broad enough that it does not sound subjectively colored or bright.

Due to its smaller diameter, it has slightly higher noise than our line of premium large-diaphragm capsules.

We include specially made US Milspec silver/Teflon multistrand hookup wire for the capsule; it is designed to avoid noise and resonance from mechanical vibration.

Microphone Body Details

The S-25 mic body is also used by brands whose names you’d recognize; it is used in commercial mics costing from $100-$300.

It is significantly heavier and higher quality than the BM-700/BM-800 donor bodies found on Ebay.

In the Box

The S-25 kit includes:

our 150mm microphone body, with XLR3 insert pre-installed
the TSB-2555 capsule
our custom mounting post/harness for the TSB-2555
the ETL1 circuit kit
the most detailed and clear DIY instruction manual we’ve ever produced
all the screws and wires needed to build the microphone. Just add solder.
For a limited time, we are bundling a swivel mount free with every S-25 kit.

What is the difference between the S-25, S-12, S-47, S-87?

The S-25 is Cardioid-only. The other S-series mics can optionally be built as Cardioid/Omni.
The S-25 has a medium-diaphragm electret capsule, rather than a large-diaphragm “true condenser” capsule.
The S-25 has slightly higher self-noise than the other mics, due to its smaller capsule.
The S-25 has lower sensitivity than the other mics, due to its capsule’s characteristics.
The S-25 has only a single PCB, no DC converter, and is easier to build.
The S-25 is significantly lower in cost.
The S-25 simply sounds different. Its capsule has a unique response curve, unlike the K47 style, CK12 style, or equalized K67/K87 style found in the other models.