Seas A26 10" 2-way Kit PAIR (based on the classic A25)

Price: $835.00


Manufacturer: Seas Prestige
Product ID : A26 Kit Pair
Weight: 16.00 lbs
Manufacturer: Seas Prestige
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Seas A26 10" 2-way Kit Pair - a new spin on a true classic!

Price is for a PAIR

Designed by Håvard Sollien & Diego Ivars at the SEAS R&D laboratory.

Seas of Norway and Madisound are excited to provide the A26 speaker kit. This kit utilizes the A26RE4 10" classic paper cone woofer and new T35C-002 1.5" textile dome Excel line tweeter, in a 1 cubic foot aperiodic enclosure (12 3/16" W x 20 1/16" T x 10 1/4" D).

Carefully designed drivers with complementary response characteristics allow for a crossover network using only two components. The classic 10" paper cone woofer is run full range and the tweeter is rolled off by a capacitor. The 10 ohm resistor can be adjusted to meet your listening preferences. We suggest using a bi-wire cup so that you can make the resistor adjustment outside of the cabinet, using the resistor as the jumper to the tweeter plus terminal. 3 different resistor values are included with the kit.

After spending several days with the A26 during its debut at the Rocky Mountain Audio Fest and later at Axpona in Chicago, we fell in love with the speaker. It has a very warm and comfortable sound, as you would expect from a driver combination like this. It is actually pretty true to the sound from the original A25, but with much better highs and slightly more dynamic overall presentation. The 1.5" dome Excel tweeter has no problem with the simple slope and low crossover point. Although people often talk about the extended highs of tweeters, often beyond the audible listening range, the true magic occurs in the lower frequencies and this tweeter excels in that range.

The aperiodic loaded woofer and excellent roll off on the low end of the tweeter has resulted in a speaker with very good transient response. Pure, simple, and elegant.

Link to Seas A26 Application Notes


Each A26 Speaker Kit Includes:


Optional Items From Drop Down Menus:

  • (2) Pre-finished Cherry Cabinets (as pictured) w/ TD-CUP input cups included
  • (2) Input Cups - or - (4) Binding Posts - if not purchasing cabinets
  • Alternative Capacitor Options


All kit pricing shown includes at least a 10% discount on all drivers, parts, and cabinets!


      Beautifully Simple Crossover Network

      For the kit we use the Mundorf Supreme capacitor for its low distortion and musicality. 

      The crossover closely follows the original A25 design, and is a model of simplicity. The use of linear drivers with complementary roll off characteristics allows for excellent performance  without the need for complex filter networks. The well behaved roll off of the woofer’s paper cone, aided by the four layer voice coil, allows it to be connected directly to the amplifier, just as in the original. The tweeter is easily matched to the woofer using a first order network; consisting of a single capacitor (3.3μF), along with a series resistor (10) for level matching. The resistor value can be adjusted to fine tune the tweeter level (12, 10 or 8.2). 

      Tweeter Level Options

      We recommend using the the TD-CUP dual binding post input cup for ease of tweeter level adjustment. Wire the tweeter to the top set and the woofer to the bottom set. Remove the (-) strap between the top and bottom binding posts, and insert the resistor in it's place, and tighten down the binding posts. This will allow you to swap resistor values to taste without having to open up the cabinet to make those changes. 

      Seas Prestige A26RE4 Woofer

      • A classical paper cone and matching natural rubber surround produce a smooth response and reduces potential resonance problems.
      • A four layer voice coil provides a well behaved roll off characteristic.
      • The magnet system has a T-shaped cross section of the pole piece for low modulation distortion.
      • Extremely stiff and stable injection moulded metal basket keeps the critical components in perfect alignment. Large windows in the basket both above and below the spider reduce sound refl exion, air fl ow noise and cavity resonance to a minimum.

      Woofer Curve

      Seas Excel T35C-002 Tweeter

      • The T35C002 is a classic dome midrange tweeter with high sensitivity and a smooth, extended frequency response.
      • A coated fabric dome with integral surround manufactured by Dr. K. Müller in Germany ensures excellent performance and consistency. This supplier was among the first in the world to offer fabric dome diaphragms, and did produce the diaphragm for the famous 1.5” Dome Tweeter H087, developed by Seas in 1968 for the Dynaco A25 speaker.
      • A small, high efficiency Neodymium ring magnet in a carefully designed system contributes to high sensitivity and low distortion. The top plate and T-yoke are CNC machined for excellent precision. A well damped vented pole and a rigid rear chamber ensure a low resonance frequency and smooth response.
        A generously underhung 35mm voice coil wound from copper-clad aluminum wire further enhances the sensitivity. Flexible lead-out wires and venting holes in the aluminum coil former help reduce noise to a minimum.
      • A 7 mm thick precision machined aluminum front plate with moderate horn loading ensures linear frequency response and represents an extremely stable platform for the magnet system and the moving parts.

      Tweeter Curve


      The Enclosure Design and Stuffing

      The SEAS A26 loudspeaker is based on a 28-liter cabinet. Position of the drivers and dimensions of the cabinet walls and vent opening are all very similar to those of the original Dynaco A25. For best performance, these dimensions should be followed closely. Adding internal bracing to stiffen the cabinet is a good idea for the advanced builder, and will further enhance the performance.

      The cabinet stuffing (50g) is distributed evenly inside the box. The highly damped vent acts as an acoustic resistor, resulting in a non-resonant (aperiodic) system. The quantity of polyfill stuffing used in the vent is 12 grams. We suggest mounting a piece of screening material over both sides of the vent to hold the stuffing in place. Decreasing the vent stuffing will improve the time response of the bass system, but will lower the bass output due to the lowered Q. If, on the contrary, more polyfill stuffing is used, the enclosure will behave closer to a sealed box and a higher Q will be obtained. However, the time response will be slightly deteriorated. We find 12 grams of polyfill to achieve the best balance between the time and frequency performance of the bass system. This amount of stuffing is based on measurements and extensive listening tests. The result is a smooth, yet detailed reproduction where the entire frequency range is in balance. We encourage you to follow the above guidelines, but you may also try experimenting with the stuffing quantities yourself, to achieve your preferred bass performance. (Madisound uses a strip of acoustic foam instead of the fill, and the speaker measured and sounds the same. At the RMAF show designer Diego Ivers also agreed that it was perfectly fine to use this material. Kits that we provide will be sent with the foam as it is much easier to use.)

      Madisound A26 Cabinets (optional)

      The Madisound A26 Cabinets are made in the USA and constructed of high quality MDF and finished with a real cherry wood. The only side not veneered is the back, which features an attractive piano black finish. The front baffle is cut for precise flush mounting of both the woofer and tweeter. The back side is cut for a precise flush mount of the TD-CUP dual binding post input cup. Also included are removable magnetic grill covers finished with a retro style white grill cloth.

      Cabinet Dimensions: 12 3/16" W x 20 1/16" T x 10 1/4" D

      Listening Room and Placement
      High quality stands should be used to bring the tweeter approximately to ear level or slightly above. Even in the best listening room, it is important to determine the positions where the loudspeakers will perform optimally. Placing the cabinets too close to the walls or corners will result in more powerful bass, but may also cause response irregularities in the bass/midrange area. Some experimentation is recommended in order to find cabinet positions that result in a good tonal balance and freedom from coloration.

      The tweeter diaphragm is relatively large for sensitivity reasons. Consequently, the highest frequencies are more directional, making it worthwhile to experiment with toe-in of the enclosures towards the listening position.

      The SEAS A26 is a refined, yet simple and fun loudspeaker, meant for enjoying your music to its fullest! 

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      Product Reviews

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      Reviewed by waterclocker
      waterclocker bought "Seas A26 10" 2-way Kit PAIR (based on the classic A25)" on our website
      06/29/2018 - 05:15:55 PM
      Search is over
      With as much praise as the original vintage Dynaco A25 get, I knew I had to hunt down a pair. The challenge of hunting down a pristine pair set in after seeing many listings for overpriced and poor condition examples. Not to mention them arriving safely if not found locally. In comes the A26. I came across this kit in my many searches and researched it's performance in popular DIY audio forums.

      I decided to go the easy route and purchase the cabinets also. This made the build a snap and they are very well made. I had a small cosmetic issue with one of the drivers and Madisound was quick to make things right. They were also very helpful with clarification on the assembly. I would recommend picking up a tube of Goop to secure the foam inside and soldering the wires inside vs using the crimp on clips.

      On to their performance! These have easily outclassed my other vintage speakers! The included tweeter really steals the show with the Mundorf Gold/Silver/Oil option. Any source is accurately represented and upstream changes in gear are very noticeable. They do not sound harsh or bright unless your gear is tuned that way. I love their sound with my Inspire KT-150 Hotrod tube amp, sweet sounding and very realistic clarity. Probably not the ideal match for a single ended tube amp, but the results are impressive in a smaller room with enough bass for most recordings. Pairing them with my Pioneer SX-980 worked nicely in a larger room and they benefit from the extra power with more low end slam. Anyone looking for a vintage style speaker with high end sound should not pass up this kit!

      My only minor complaints would be the fabric grills and the spade connectors. The grills look really nice, but they affect the clarity of the sound. The material used is not as acoustically transparent as I would like, but you would probably run into the same issue on various vintage speakers anyway. They are easily removed and the speakers look great without them. The spade connectors didn't seem to fit well on all the connections. The speaker terminal cup mainly. No big deal though, I would rather solder my connections anyway. They could be a little fiddly if you are trying to build without soldering. All in all though, the quality and performance overshadows these issues. Highly recommended and I look forward to ordering from Madisound again!!
      Reviewed by rkuimelis
      rkuimelis bought "Seas A26 10" 2-way Kit PAIR (based on the classic A25)" on our website
      01/25/2018 - 10:00:12 PM
      Long overdue feedback. Very happy with the SEAS A26. Use them daily as my main speakers. They work especially well with my First Watt diy Class A amps (M2 and VFET). Fun speaker that does most things well. Nice tweeter. Was expecting more low end from the large woofers, but things really came into balance after I rotated in the class A amps.

      This was my first ground up build. I opted for some beefy internal bracing and surface damping. Build details here:

      Reviewed by bdbender2
      bdbender2 bought "Seas A26 10" 2-way Kit PAIR (based on the classic A25)" on our website
      01/02/2015 - 09:30:03 AM
      Wide Boxes Sound Good
      Back in the day I had several ARs, a KLH, and I still have an Advent. Fate never brought one of the Dynacos my way although I thought the stuffed vent was intriguing.

      I have been listening to skinny speakers for years: small Focals, SEAS Loki kits, Snell skinny towners. In 2012 I built some Eton S7s, and did a review here on Madisound that links to DIY Audio. I also have some Focal 918s at the moment.

      The Focal 918s are really nice speakers, with molded asymmetrical cabinets and reall good drivers in them. I recently changed from tube amplification (back) to solid state, and the Focal tweeters didn't like it much. The S7s went back in the system, and the Focals went back in the shipping boxes and back out into the shed. (Surprised the heck out of me.)

      I built the A26s with the Dynamat and the Mundorf fanciest "gold" tweeter. I soldered the input connections and did not bi-wire. Used the 10 ohm resistors. No photos for this build, it was really straightforward.

      It took a couple of weeks to get used to the appearance of those fat speakers up on stands in my living room, and I ended up with shorter stands (EPOS ST15), but boy is the sound "out in the room". The larger tweeters just sound great. The S7s are back in their boxes, too, out in the shed.

      I have been listening to some of the Blue Note reissues from Acoustic Sounds. I am of a certain age and can't hear much above about 8,000Hz any more, but I can say that well-recorded cymbals sound full and you can hear the shimmer. The saxophones, too, just sound wonderful. At the "audiophile" end of things, Shelby Lynne is all there, and so is Daft Punk. (Although I should point out that I am running self-equalizing subwoofers below about 46Hz.)

      Be sure to check WAF, though. These fat tan obviously veneered things replaced skinny shiny piano black things in my house...
      Reviewed by
      02/27/2014 - 02:00:21 PM
      A True Dynaco A25 Clone
      I own several pairs of original Dynaco A25s. This new kit is as close to the originals than any other clone I have evaluated. They have a much better high frequency extension than the Dynacos however. Because of the this the clarity is better with better imaging while still maintaining the mid-range warmth. Do not go cheap on the capacitor or resistor. I recommend the mundorf silver/oil as it is the best band for the buck in this kit. The enclosures provided by madisound are gorgeous. I absolutely love the original A25s but the Seas A26 takes them to an entire new level.