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Synergy SYN-412 EXT 4 x 12-inch Extension Cabinet , $1,399.99 - Add to Cart Skip to Product Information

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

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 October 2026

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Synergy SYN-412 EXT 4 x 12-inch Extension Cabinet
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 October 2026

Tailor-made for Your SYN-50 Amp Head

This article was Written By

Our Product Research Team

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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

Warranty Info

Sweetwater's FREE 2-Year Total Confidence Coverage Warranty

Extra peace of mind at no extra cost.

  • Save money with FREE parts and labor
  • Get back to making music with the industry's fastest turnaround time
  • Fix it the first time with our award-winning, factory-certified Service Department
Learn More about Total Confidence Coverage

Offer applies only to single-receipt qualifying purchases. Select manufacturers may require that only the manufacturer’s products qualify towards the minimum purchase amount needed to be eligible for promotional financing. Otherwise, an invoice that meets the minimum purchase amount and contains at least one qualifying manufacturer product is eligible for promotional financing. No interest will be charged on promo purchase balance, and equal monthly payments are required on promo purchase until it is paid in full. The payments equal the amount financed divided by the number of months in the promo period, rounded up to the next whole dollar. These payments may be higher than the payments that would be required if this purchase was a non-promo purchase. During the last month(s) of the promo period the required monthly payment may be reduced due to the prior months’ rounding. Regular account terms apply to non-promo purchases. New Accounts as of 07/31/2025: Purchase APR is 34.99%. Penalty APR is 39.99%. Min Interest Charge is $2. Existing cardholders: See your credit card agreement terms. Subject to credit approval.

Offer applies only to single-receipt qualifying purchases. No interest will be charged on the promo balance if you pay it off, in full, within the promo period. If you do not, interest will be charged on the promo balance from the purchase date. The required minimum monthly payments may or may not pay off the promo balance before the end of the promo period, depending on purchase amount, promo length and payment allocation. Regular account terms apply to non-promo purchases and, after promo period ends, to the promo balance. New Accounts as of 07/31/2025: Purchase APR is 34.99%. Penalty APR is 39.99%. Min Interest Charge is $2. Existing cardholders: See your credit card agreement terms. Subject to credit approval.

The estimated required monthly payment shown which excludes taxes and delivery equals the amount financed divided by the number of months in the promo period, rounded up to the next cent. During the last month(s) of the promo period the required monthly payment may be reduced due to this rounding. These payments apply only with the financing offer shown. If you make these payments by the due date each month, you should pay off this amount financed within the promo period, if it is the only balance you are paying off. If you have other balances on your account, this payment will be added to any other minimum monthly payments.

Applies only to select items from this manufacturer. Ask your Sweetwater Sales Engineer for more details.