Sterling ST77 Circuit Upgrade Kit

$ 199.00 $ 229.00

As of 2023-11-28, we have one remaining ST77 kit. We do not plan to restock this design. If the button above reads "sold out" rather than "add to cart," that means this product is no longer available.


We have developed a replacement circuit for the Sterling ST77. The circuit topology is a single-stage JFET with output transformer. We have optimized this circuit to create even-order harmonics, which add richness, saturation, and texture to your tracks.

This product is identical to our best-selling T-84 circuit kit, adapted to fit the ST77 chassis.


Features & Benefits

The new circuit has lower noise and superior sonics to the original. Combined with the RK-12 capsule, you can build our T-12 mic into your ST77 housing.

The new circuit provides internal switches for a 10dB pad and polar pattern (Cardioid/Omni). The pattern switch requires a dual-diaphragm capsule, such as the RK-12 or RK-47.


In The Box

You'll receive our T-84 circuit parts (including transformer) and instructions, with a PCB designed to fit the Sterling ST77.


Installation Notes

The installation process is slightly more challenging than some of our other kits, for these reasons:

  • We do not provide step-by-step instructions for mounting the transformer. The transformer could be taped to the back of the PCB, or installed within the transformer can that houses the stock transformer.
  • We do not provide step-by-step instructions for disassembly of the Sterling ST77. (In a nutshell, you just need to remove the old PCB(s) and transformer, and preferably the capsule too. Then install the new parts.)

If this is your first DIY mic upgrade, we recommend starting with something simpler. Or, see below.


    Mod Service Option

    We can upgrade your Sterling ST77 for you; contact us for details.

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