Center Channel Speakers

MartinLogan Stage X Electrostatic Hybrid Center Channel Speaker

ARTICLE INDEX

The Design

The Stage X has a thin film tweeter which is pleated and situated between permanent magnets. The music signal flows through the thin film. Pleating the thin film allows for higher efficiency than conventional ribbon tweeters, and is stronger as well. Here is a photo of the Stage X tweeter.

Stage X

 

This tweeter is mounted on the rear and in the center of the ESL panel.

ESLs work by having a very thin plastic membrane mounted between two closely spaced perforated metal stators. A static DC bias voltage is applied to the membrane, and the speaker voltage goes to the stators. As the voltage on the stators varies in frequency and intensity, the static charged membrane is attracted and repelled accordingly, and this produces the sound. A ribbon works by having a thin metal strip, which sits between two sets of permanent magnets. When the audio signal passes through the metal strip, it produces an electromagnetic field that is attracted and repelled by the permanent magnets according to the variation in the audio signal. What's called "Quasi Ribbon" consists of a circuit path etched onto a thin plastic ribbon. The current passes through the circuit, and the entire plastic ribbon moves. The Stage X uses a thin film with a voice coil printed in it, and then the film is pleated. The audio signal passes through the printed voice coil, and the thin film then moves, producing the sound.

The ESL panel itself, handling the midrange frequencies, is 7.5" x 18" in size, and is curved inward, towards the rear of the speaker, as shown below. You can also see that the grille is made up of very small round holes that look hexagonal due to the insulation that is applied. There are two of these steel panels with the holes, placed very close together. The holes have a very thin boundary, to maximize the amount of air that can flow through the grille. On the left side, the grille continues, but one of the woofers is behind it. The ESL panel is in the middle. You can see the tweeter through the center of the ESL panel, and some light from my equipment rack is seen through the right side. So, when looking directly at the speaker, the middle is transparent, but the sides have the cone woofers and their enclosures behind them.

Stage X

 

Two 6.5" woofers with small sealed enclosures are situated at each end of the speaker.

The rear of the Stage X can be seen in the photo below, and you can see the tweeter in the middle of the ESL panel. There is a mounting bracket attached which can be rotated forward and backward. It is broad enough that it can sit on a speaker stand, but it is best to bolt the speaker to the stand rather than just letting it sit on it, unattached. You can also bolt it to a wall, for example, underneath a flat panel HDTV that is also mounted to the wall.

Stage X

 

The speaker binding posts are five-way. A small jack is at the bottom for connecting a wall-wart cable that supplies bias voltage to the thin membrane between the stators.

Stage X

 

Here is what the Sage X might look like in a home theater setting.

Stage X

 

Besides black, the Stage X also comes in a very attractive cherry veneer, shown below. This is the color of the review sample I received.

Stage X