Seymour Duncan STC-3A 3-Band Preamp for Active Pickups



  • 3-Band: 2-Pickup, 4-Knob
  • VPP - Bl - Treb/Bass Stack - Mid
In Stock Today

These are in our warehouse. Order it before Noon (Eastern Standard Time) and we'll ship it out today, otherwise we'll ship it the very next business day.


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Control Configuration

  1. Volume Push/Pull(Slap-Switch)
  2. Blend
  3. Treble/Bass Stack
  4. Mid

High headroom, low-noise, 3-Band active onboard EQ preamp designed for use with active pickups. Comes with prewired 4-knob harness.

Our Tone Circuits will add a tremendous amount of on-board tonal versatility to any dual pickup bass. This design enables players to boost or cut specifically focused frequencies in order to achieve signature tones and to dial in a great sound no matter what the situation. We even added two small trim pots on the circuit board can be tweaked to preset the frequency contour EQ just the way you want.

The STC-3A Tone Circuit provides a 4-knob prewired harness that includes a stacked basstreble control, a midrange control, a master volume, a blend control, and our proprietary Slap Switch. The treble control can produce a wide ranging, extremely usable response that is brilliant, yet smooth without being brittle. Our midrange control can be used to just slightly remove excess midrange honk or to add sonic power that will really make solos jump out. The bass can be reduced to tighten up a boomy instrument, or it can be increased to add warmth and punch.

The Slap Switch is a pushpull located on the volume control. Pulling up on the volume knob will engage the special EQ contour voiced specifically for slap playing. The STC-3A will work in any bass that is equipped with two active pickups and has space for 4 control knobs (volumeslap switch, blend, concentric bass and treble controls) and a single 9v battery in the control cavity. Two 9v batteries can be wired together in series for added headroom.

Package Includes

  • All necessary mounting hardware
  • High-quality potentiometers on pre-wired harness
  • Battery Clip
  • Stereo Jack
  • Black Anodized, knurled, dome-style knobs
Power Requirements 9Vdc (up to 36V may be used for increased headroom)
Current consumption 1.85mA @ 9V (current consumption is higher at higher voltages)
Maximum signal swing 2.7V @ onset of clip
Gain Unity *
Thd <0.01% *
Noise < -95dBv *
Tone control center frequency / Q / range +/-
Bass 30 Hz / .30 / 12dB
Midrange 650 Hz / .68 / 14dB
Treble 6.5 KHz / 1.2 / 15dB
Slap contour center frequency / Q / range
Bass Boost 83 Hz / 1.79 / +3 to +9dB
Midrange Cut 633 Hz / 1.12 / -3 to -11dB

* Noise & thd measurement taken with tone controls set to flat position

Question: Where Can I Buy a Seymour Duncan STC-3A 3-Band Preamp for Active Pickup?

Answer: You can buy this from Best Bass Gear by Calling 877-839-3531 or Emailing us at or chatting with our Bass Techs


Rate and Review this item
Verified Buyer
It's an amzing preamplifier
By Xavier
Really easy to assemble and solder. Connectors and pins are of very good quality. The sound is amazing, really deep and accurate. EQ is efficient yet not too pushy. definitively a must have.
Verified Buyer
Easy to install and a great deal
By michael
These pickups were easy to install. I only had to solder pickups, bridge grounds and input jack. The seymour STC-3A is quiet, well balanced and an affordable tone circuit. I installed this in a ibanez prestige bass that had a dry tone circuit, noisy pots and electronics that kept cutting out. My bass sounds and performs great now. I would recommend this product to others.