My Cart

Your Shopping Cart is Empty

Shop All Stores

Zaph|Audio SB12.3, SB Acoustics 12", 3-Way - PAIR

Zaph|Audio SB12.3, SB Acoustics 12", 3-Way - PAIR
Click to enlarge
Price: $995.00
Product ID : sb12.3
Manufacturer: SB Acoustics
Weight: 72.00 lbs
E-mail to a friend | Add To Wish List


  • Buy 10+ and get an additional 10% off


Zaph|Audio SB12.3 ~ SB Acoustics 12", Dual Midrange, 3-Way, Parts Only
Price shown is for a PAIR

Madisound is pleased to bring you our big SB Acoustics 3-Way kit, the SB12.3. We often receive requests for large and in charge speaker systems. This kit is our hi-fidelity answer. Once again we teamed up with John Krutke of Zaph Audio for his skilled design work. This kit is fully documented on the SB12.3 page on the Zaph Audio website.

SB Acoustics drivers have quickly established themselves as serious performers within the DIY speaker building community. We feel this line of drivers is a perfect choice for a high performance 3-Way design. There is no concession in the driver selection or crossover design, yet the final price is more than reasonable for a system of this stature.

Each speaker is anchored by a 12” SB34NRX75-6 woofer for bass duty. This woofer features a stiff paper cone with 3” voice coil, an open structure cast frame, huge ventilation through the pole piece, and 11mm of X-max. The SB34NRX is a Madisound favorite and does not disappoint here in a sealed box alignment.

Critical midrange duty is carried by a pair of 5” SB15NRXC30-8 drivers. These units feature the same proprietary composition paper cone and a similar open structure cast frame. The extended length copper clad pole piece helps enable very low distortion through its frequency range. The SB15NRXC already has quite the DIY following for mid/bass duty, and we are excited to implement it as a dedicated midrange in this project.

High frequency reproduction is performed by the SB29RDC-C000-4 ring dome tweeter. This is the flagship tweeter of the SB Acoustics line and one of the best tweeters we know of. The SB29RDC features a unique fabric ring dome with large roll surround, a low resonant frequency, and a smooth extended response.

If you desire a large speaker system and demand zero compromise in sound quality, look no further - the SB12.3 is for you!


  • Frequency response: 37 Hz – 20+ kHz, Anechoic F3: 37 Hz
  • In room response even lower. This system has plenty of bottom end!
  • Recommended amplification: 50 W – 250+ W per channel
  • Crossover frequencies: 220 Hz & 2.2 kHz 
  • System sensitivity: 92 dB
  • System impedance: Minimum 4.3 ohms, Avg. 5-6ohms
  • Most amplifiers will have no problem powering these speakers
  • 46” Tall x 16” Wide x 14” Deep (see cabinet drawing)
  • 3.75 cubic foot sealed airspace for woofer
  • 0.58 cubic foot sealed airspace (separate from woofer) for dual midrange drivers

Each SB12.3 Kit Includes:

You may also choose to purchase the optional accessories package. The accessorie s package is offered at a discounted price, and will provide you with all the miscellaneous speaker building parts that you need to complete your kit.

Optional Accessories Package Includes:

All pricing includes at least a 10% discount on all drivers, crossovers and parts.

Crossover Information:

Crossover parts were carefully selected for both high quality sound reproduction and adequate power handling. The series circuits feature a low DCR Sledgehammer 15 AWG Steel Laminate inductor for the woofer, Solen Fastcap & Sidewinder 16AWG Air Core inductors for the midrange, and Clarity SA Caps for the tweeter. Mundorf MOX resistors are also used throughout the tweeter circuit and in series with the midrange. The crossovers are professionally assembled on three circuit boards. The midrange is on a Matrix Double, and the woofer and tweeter are each on a Matrix. You can bi-wire/amp or even tri-wire/amp the SB12.3 if you desire.

Crossover Upgrade Options: (as described above, but with the following changes)

  • Clarity ESA Caps in the tweeter circuit
  • Mundorf M-Cap Supreme caps in the tweeter circuit
  • Clarity PX Caps in the series midrange circuit
  • Clarity PX Caps in the series midrange circuit & Clarity ESA Caps in the tweeter circuit
  • Clarity PX Caps in the series midrange circuit & Mundorf M-Cap Supreme caps in the tweeter circuit

Miscelaneous Notes:

Cabinets are not available for this kit through Madisound. The speakers are simply too large to make this logistically possible.  Tyler Acoustics built the walnut veneer cabinets you see here and he is willing to build this for people who are interested.  You can choose your own veneer and he will quote accordingly.  Please contact Tyler directly.

Each cabinet uses 3.5 pounds of Acousta-Stuf internal fill. Use 3 pounds in the main woofer chamber and ½  pound in the midrange chamber. You should also line the rear wall and side walls of the cabinet with acoustic foam sheets. These damping materials are included with the optional accessories package.

We recommend using the TD-CUP dual binding post input cup, and it is supplied with the optional accessories package. Run one set of wires from the bottom set of binding posts to the woofer crossover. Then run one set of wires from the top set of binding posts to the midrange crossover - and jumper a set of wires to the tweeter crossover from there. Another option is to run a TD-CUP and a standard input cup, or 3 sets of binding posts on the back of your speaker. You would then wire each crossover to its own set of binding posts.

The SB12.3 rounds out the Zaph line of Madisound kits, giving you multiple kit choices from best lines of drivers available. If this specific kit doesn’t suit your project goals, please consider the new ZA5 family of kits or an established favorite; the Seas SR71 or Scan-Speak ZRT.

SB12.3 Drivers

Professionally Assembled SB12.3 Crossovers

SB Acoustics Ring Dome Tweeter

SB Acoustics Midrange Side View

SB Acoustics Woofer Riew View

SB12.3 Tweeter Crossover Detail

SB12.3 Midrange Crossover Detail

SB12.3 Woofer Crossover Detail

Product Reviews

Login or Register to write the first review.