GDA125 description

One word comes to mind, when describing the sound of a JJAZ speaker including the GDA125: Effortless!

The see through experience is phenomenal, and every detail on
the CD or LP is mercilessly reproduced by the speakers.

Airiness and the “being there” experience is benchmark standard. Nothing nice, sweet or painted with big brushes! But a reference level of details and "live at home" soundstage.

The drivers are the best there is! The crossover is a lection of thoughtful design, high-end components and layout. The cabinets are a work of art when it comes to a correct speaker enclosure.
 

The 5" HDS driver:
 

This cone is a result of more than 75 years experience of work from the Danish Tymphany engineers (the merged Scanspeak/Vifa and Peerless companies).

Nothing else comes even close to the ability of this cone regarding natural sound reproduction.

Q. Why paper based cones?

A.     Paper has ideal material characteristics, namely: stiffness, self-dampening and organic sound.

The voicecoil: A Kapton former with an aluminum wire coil. It is light, strong and will transfer even the smallest music signal to the cone. Giving you all the micro details present on the source media whether it is a CD or LP.

Q. Why not titanium or glass fiber former?

A. Kapton has the best strength/weight/heat transfer ration.

Q. Why not copper or silver wire?

A. Aluminum has the best ratio regarding weight and conductivity.

The rubber surround: Soft high quality rubber, resulting in no loss of details and ensuring stability over a long period of time.

Q. Why not a foam surround?

A. Foam degrades over a period of time. What might be good for the first year,
will over time change the parameters of the driver, and cause deviations in the response characteristics.

The motor: A result of numerous tests in combination with the moving parts. The result is a top class solution that combines high sensitivity, perfect bass response and class setting integration with the tweeter.

Center of the motor system is the T-yoke. Clad with a copper foil on top for a minimum high frequency distortion, as well as a short-circuit aluminum ring under the gap to minimize bass response distortion.

The top plate is a low tolerance production, thick, quality steel plate. With magnet gap tolerances measured in 1/100mm.

Magnets are made from top of the line ceramic-based materials. It ensures a uniform magnet field in the gap and an ever lasting strong and stable flux.

The VCRDP: A JJAZ HDS 5" Woofer is furthermore equipped with the unique VCRDP (Voice Coil Resonance Damping Plug). One of the problems with other woofers is that due to production techniques the coil former needs to extend into the cone. This piece of former often diffuses the micro details and thus causes a response distortion.

The JJAZ solution is to put a special foam plug into the former. The foam must exhibit low air-flow resistance in order to avoid power compression caused by the movement of the cone. At the same time the foam plug removes all vibrations and resonances in the piece of coil former that extends into the cone.

Q. Why not a phaseplug?

A. It would not remove the problem of unwanted resonances and vibrations in the coil former. Furthermore the phaseplug introduces other problems such as non-linear phase distortion.

Q. Why not a traditional dust cap?

A. Air displacement under the dust cap is a serious problem and the best way to avoid it is to make sure it is not there in the first place. Imagine a dust cap with a trapped amount of air beneath it. This amount of air pushes strongly on the dustcap when the cone moves and causes the dust cap to play a tune of its own.

The Scan-Speak Ringradiator: There is not much to say about the tweeter. It is as good as it gets. All "tweaks" we know of are either a waste of time and money, or degrades the high frequency reproduction instead of improving it.

Q. Why not…?

A. There are none. The tweeter is well known worldwide as the best there is. It’s as simple as that. The one and only tweeter with next to no sound of its own, ultimate transparency!
 

The crossover: The crossover is hard wired on the resonance free back plate and made up of the best possible components.

Large polypropylene capacitors capable of handling hundreds of volts and therefore stays stable more than a lifetime.

The coils are large copperfoil types with minimum resistance and spun on a wood centre eliminating flux overflow in a metal centre core.

The resistors are passively cooled to ensure stability at every sound pressure level and are of course non-inductive.

Q. Why not an external crossover?

A. An external crossover is unhandy. If the internal one is made and placed correctly the inside vs. outside placement does not make a difference.

The box: It is heavy and of high quality MDF with extensive bracing and an acoustically optimized shape.

Curved sides to minimize front diffraction problems as well as gaining extra stiffness. Have you ever seen a wood based instrument made up as a box with straight sides?

The insides of the box are damped to ensure no opposite same mass problems. This is done to avoid increasing resonance.

The box is made with different wall thicknesses to further avoid resonance problems.

Q. Why MFD, and not composite.

A. MDF has an overall advantage over most other materials, including cast composite cabinets.
 

The port: The bass port is damped to avoid unwanted resonance. It flairs to avoid air turbulence and is placed woofer symmetrical to ensure optimum equal woofer bass response.

Q. Why a damped plastic port, and not paper or composite.

A. The advantage of the cast plastic port made in self-damping plastic combined with the unique damping developed by JJAZ is the ideal combination of form, weight and function.
 

Conclusion:

Q. Is the JJAZ GDA125, the best 2-way speaker there is.

A. Yes.

Others might sure pass the JJAZ GDA125, in one aspect or another. But no other gives you the overall clarity, level of detail and soundstage. All on reference level!

GDA125 Specifications