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Dynaco A-25

Aperiodic Loudspeaker System (1971)

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Dynaco A-25

Description

The Dynaco A-25 aperiodic loudspeaker is a compact, high performance two way speaker system.

A 10 inch extended excursion woofer is matched to a specially designed soft dome tweeter with a dual section high pass filter at 1500Hz, in a cabinet design which achieves a uniquely non-resonant bass response.

The aperiodic, or non-resonant characteristic of the A-25 provides an unusally uniform impedance characteristic throughtout the bass range of less than 2 in 1.

This design utilises an acoustic impedance system which provides variable volume action rather than the totally enclosed cabinet of the acoustic suspension principle or the tuned port of the bass reflex.

Specifications

Type: 2 way, 2 driver loudspeaker system

Frequency Response: 30Hz to 15kHz

Power Handling: 35W

Recommended Amplifier: 60W (maximum)

Crossover Frequency: 1500Hz

Impedance: 8Ω

Bass: 1 x 10" extended excursion

Tweeter: 1 x soft dome

Finish: oiled walnut, rosewood, teak

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Reviews

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Reviewed Sep 25th, 2017 by M.Tours

Fantastic loudspeaker. I like the aperiodic system in which a loudspeaker is not open or closed, but in between. Air inside the loudspeaker makes fibres in the slit move, thus eating up most -out of fase- waves. The woofer makes greater excursions without loss of control. This gives it a freedom of boxiness, while retaining firm bass. Most Dynaco A25's have Alnico magnets (Aluminium for strenghth and Nickel and Cobalt for magnetism), very nice motor for the system. The dometweeter is more usefull for parties (big size) it lacks some top-end. I replaced it for Morel MDT-20's. Same mid, but higher top-end. These seem not available anymore. But SEAS or Scanspeak might have other options.

rating
Reviewed Aug 26th, 2017 by AudioGMan

I bought a pair to hear what all the hoopla was about and I have to admit they sound pretty good for what they are. Good imaging and excellent transient response in the proper setting. Easy to drive due to the aperiodic design that helps flatten the impedance curve. Vocals are well defined and the minimalist design approach is a testament to the use of carefully selected drivers. The cabinets are small enough to actually be used on a bookshelf. Unusual for a 10 woofer speaker. As with most speakers of this era this style grill has always been ugly in my opinion but those can be redone. I always listen without the grills and like AR and Advent they won't win a beauty contest with the grills off. I dislike the tweeter pot design and think replacing that with a continuously variable pot would be better and more reliable. The capacitor looks like a big waxy paper style so a better modern one would probably improve the tweeter's sound. These speakers are best suited for a small to medium room as they can't handle a whole lot of power. If you want a speaker that can play loud for an extended amount of time look elsewhere or you'll be smelling overheated voicecoils. Use a powered subwoofer if you want low bass so that the Dynacos can shine. All in all I think they are great speakers but not so much that they justify what they sell for. But like with other vintage speakers people are paying ridiculous prices for them.

 

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