Another Pair of Bookshelf Speakers - JM Lab Electra 906

pjdami

I've always wanted a pair of these for the tube 2 channel rig. Finally came across a minty pair at a good price and bit the bullet to add to my speaker collection.

90 db efficient and 8 ohms, easy load for my Rogue tube amp. Currently, I have these running with the Rogue, Cary tube pre, and Myryad cd player. All Kimber wiring except for my custom DIY powercords.

The Electra features a 6.5 inch "W" design mid-bass cone which is two pieces of glass tissue sandwiched around a middle foam layer. Bass is speced out at 50 Hz but it definitely seems to hit a bit lower than that. Very fast and tight bass from this speaker.

The tweeter is called a Tioxid inverted dome. This is a concave domed tweeter as opposed to the more tradition convex dome tweeter. It is a brilliantly detailed tweeter and a great match for a tube setup.

I thought these were going to be more forward sounding than they are. They are not as forward sounding as the Magnepan MMGs that I own but more forward sounding than the Spendor 1/2s. Excellent speakers and I'm going to enjoy them some more in the upcoming time with them. Soundstage is very good but not quite as wide or as deep as the Spendors which are probably almost nearly double their price originally in retail value.

Very dynamic and can play loud and clear. No wonder why these won the award of "European Loudspeaker of the Year" in 2002 / 2003. Yes, the French can make some fine loudspeakers.

They remind me a lot of the LSi 9s in a way. Good bass from a relatively small driver and extended detailed highs. I believe the mid-range from the Electra is sweeter though but that could be the tubes doing their trick. I never had any luck running LSi's with a tube amp as they seemed kind of lifeless. I wish Polk would make a tube friendly LSi type speaker..hint.. hint..

Here's some pics:

audiobliss

Very interesting looking speakers! Don't believe I've ever seen any speakers with an inverted dome tweeter before.

Emlyn

I've been very happy with my Electra's for both music and home theater, in fact the first pair of speakers I've been completely happy with for both purposes. Focal gets a lot of attention because of their unusual tweeter design, but I think they deserve just as much acclaim for their midrange drivers, and tight, fast bass reproduction. They also don't seem to be as difficult to setup to sound good in a room as some other speakers I've had. The 920.1 was from the series right before the 906. Excellent speakers.

DAGLJAM6

Nice speakers, i've been keeping an eye open for a smaller two-way for a low watt tubed integrated. I may have to keep these in mind.

BTW, A/bliss EPI was using inverted dome tweeters all through the 70's in their speaker line. See attached, it's what made that company (as far as sound goes)
a very "ear friendly" tweeter .

Joey_V

So the Tioxid isnt the same as their newer Beryllium tweeters, right?

All the new JM Labs speakers use the Be inverted tweeter.... which I found to be very great sounding.

dorokusai

Nice speakers Paul....when you're done with them, send them to MD.

pjdami

Joey_V wrote:

So the Tioxid isnt the same as their newer Beryllium tweeters, right?

That is correct. Here's the interesting explanation from the JM Lab website:

This brand new tweeter has been specially designed for the new Electra line. Its key features are the new generation Tioxid 5 inverted dome, optimized double magnet system and damping chamber for the rear sound radiation from the dome.

Designed along the same principles as a miniature loudspeaker, the inverted dome with its centrally fixed voice coil gives high power handling and a frequency response that extends low down into midrange frequencies. Because of this extended response, the crossover frequency can be situated low enough to eliminate the effects of ‘beaming’ from the midrange drive unit. Beaming is where the sound becomes directional or focused into a beam at higher frequencies which correspond with the diameter of the cone – for a 165mm driver this effect starts to take place at 2.8kHz, so ideally the crossover frequency should be below this limit.

The concave dome vs. the convex dome
The conventional convex dome is theoretically presented as a “pulsating half-sphere” radiating its energy at 180°. In practice, this is not exactly so, because the dome driven around its circumference moves with its shape remaining unchanged regardless of the amplitude of the signal to be reproduced. There is no “pulsating” effect here. You will see from the drawing that the coil of a convex dome is located on the dome’s edge, at the connection point between the dome and the suspension. The transfer of energy from the coil to the dome is concentrated at its rim, thereby limiting the effectiveness of the transfer of energy into the whole structure. The dome is not really emissive. The tweeter with a traditional dome therefore suffers from the disadvantage that it cannot be crossed over at low frequencies due to its poor coupling with the air and presents a phenomenon of dynamic compression inherent in the attachment of the coil to the dome. We can see then, that the “pulsating sphere” concept and its principle of equal dispersion is one that is, in practice, inaccurate.

In the case of a tweeter with an inverted dome the coil is fixed midway up the height of the dome and applies a more uniform pressure across the whole structure, with the complete unit then radiating directly into space and offering maximum efficiency. The acoustic coupling to the air is ideal. In addition to this, connection to the mid-range loudspeaker can be made at sufficiently low frequencies (2.5kHz), a key feature for enhancing the directivity of the mid-range loudspeaker.

The Tioxid 5, a new Focal-JMlab material
An evolution of the Tioxid material originally introduced for the TGU tweeter of the Grand Utopia, the Tioxid 5 offers similar levels of performance to that of Titanium in terms of mass and stiffness, but with superior damping properties. The Tioxid 5 is lighter than the original Tioxid, due to a finer deposit on the dome off just 5 microns. The impulse response is further improved by the higher internal damping factor of the Tioxid 5 giving a smooth and detailed sound free from metallic coloration.

I've been playing around with placement today and gave them more room to breathe by moving the Spendors out of the way. I also think they sound better straight ahead instead of toed-in (soundstage sounds bigger). The tweeter really freaks me out at times by projecting a sound from a location way outside of the speaker box. This has happened on several different songs and I'm going to have to start taking note of this because these are songs that I am familiar with and haven't heard an image reproduced like this.

Emlyn,
We seem to share a lot in common with speaker tastes. I love speakers the most of any audio component. I own a couple of pair of vintage Polks and also LSi. Speakers make the biggest change in sound as long as one's "core" gear are in order. I'm a huge Rogue fan now. The Rogue amp is the most musical amp I have ever owned. Its got some serious balls for a tube amp.

polkatese

Nice, Paul!