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Synergy SYN-412 EXT 4 x 12-inch Extension Cabinet

170-watt, 16-ohm, 4x12" Extension Cabinet with 2 Celestion Greenback Speakers and 2 Celestion Vintage 30 Speakers
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Item ID: SYN-412EXT
Synergy SYN-412 EXT 4 x 12-inch Extension Cabinet
Price:$1,399 and 99 cents
Special Financing - Ends Aug 2, 2026. $39/month with 36 month financing*

We Can Get It!

While this isn't an item we normally stock, we can still get it to you as fast as possible due to our great relationship with Synergy. Go ahead and place your order and we'll follow up shortly to let you know when to expect it. Estimated June 2026.

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Synergy SYN-412 EXT 4 x 12-inch Extension Cabinet
We Can Get It!
Price:$1,399 and 99 cents
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Tailor-made for Your SYN-50 Amp Head

The SYN-412 is the perfect match for your Synergy SYN-50 amp head. Loaded with a quartet of Celestion speakers — Greenbacks on the top and Vintage 30s on the bottom — this 4 x 12" extension cabinet delivers a classic British sound with thunderous lows, smooth mids, and creamy highs. Exhibiting an intricate crunch, this cab reveals the tonal complexities of your preamp modules — lows will sound full, mids will be meaty, and highs will chime beautifully. The SYN-412 features a closed-back design and durable Baltic birch construction.

Loaded with Celestion speakers

The SYN-412 is packed with a quartet of Celestion speakers. The top slots are filled with Greenbacks. Greenbacks give you a solid tone with sparkling highs and the perfect amount of bite. The bottom slots are loaded with Vintage 30s. Easily twice as loud as other speakers at the same power level, Vintage 30s handle gargantuan overdrive with precision. Together, this combination yields a classic British sound with thunderous lows, smooth mids, and a creamy, harmonically rich high end.

Synergy SYN-50 amp head sold separately.

Synergy Amplification

Merriam-Webster defines synergy as, "A mutually advantageous conjunction or compatibility of distinct business participants." With Synergy Amplification's combining of tube-amp talents that include Dave Friedman, Joe Morgan, Steven Fryette, Mike Soldano, and Peter Diezel, the name is a perfect fit. Each product is painstakingly crafted by these titans of the tube-amp world, ensuring every nuance of their legendary amplifiers is translated to your tone. For the most iconic tones in the most convenient package possible, Sweetwater is proud to offer you Synergy Amplification.

Synergy SYN-412 Cabinet Features:

  • Greenback speakers (top) exhibit a solid tone with sparkling highs and the perfect amount of bite
  • Vintage 30 speakers (bottom) produce thunderous lows, smooth mids, and harmonically rich highs
  • Reveals the tonal complexities of your Synergy preamp modules
  • Closed-back design
  • Durable Baltic birch construction

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Tech Specs

  • Configuration: 4 x 12"
  • Powered: No
  • Speakers: 2 x Celestion Vintage 30, 2 x Celestion G12M Greenback
  • Power Handling: 170W
  • Impedance: 16 ohms (mono), 8 ohms (stereo)
  • Mono/Stereo: Mono/Stereo
  • Cabinet Type: Slant (slight angle)
  • Open/Closed Back: Closed
  • Inputs: 1 x 1/4" (mono), 2 x 1/4" (stereo)
  • Construction Material: Baltic Birch
  • Height: 30"
  • Width: 30"
  • Depth: 14"
  • Weight: 86 lbs.
  • Manufacturer Part Number: SYN-412 EXT

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Reviews

Amazing cab and speaker combo
I've been swapping between different Mesa/Marshall angled cabs for a few years, but I really wanted a 'straight' cab with a bit more options. The combination of greenbacks and v-30 is amazing. You get tons of bottom end without losing the crisp mids/highs. It looks great and it sounds great. I mostly use this with my Synergy pre-amps, but also did some tests with the JCM800 studio and the lunchbox EVH 5150. Immediate sound improvement over my previous speakers/cabs!

The only improvement I could think of would be metal caps for the corners to protect it while moving between gigs. It came very well packaged though.
Music background: hobbyist