Revised MBOW1 3-Way

Revised Crossover for the Best Buy Insignia

Revised Crossover for the BR-1 Kit

Mod for Morel 403.5 3-Way


Revised Crossover for the Norh 9.0 Marble

The New Vifa Tower

Fixing the Polk RTi28

The MB20

The MB27

The Plop-in-the-Box

The Usher Two-Way

Revised Crossover for the Radio Shack LX550

Alternative Crossover for the Dynaudio Gemini

Crossover for the Revelator-RT1 Mini Monitor

Home Print This Page Font Size Font Family
The Acoustic Research AR4x

A Tale of Two Cabinets

Tweeter Comparison

The RadioShack Minimus 7

JMLab Mezzo Utopia,
Tannoy Westminster,

Measurements for the Radio Shack LX550

Proac Super Tablette

Acoustic Research AR3a

Sound Dynamics RTS-3

Stock vs Modified Gemini

NHT Super One

JMLab Mezzo Utopia, Tannoy Westminster, VMPS RM1

The following measurements were made in a very large room with a 24-foot ceiling.  The room responses are not comparable to similar plots appearing elsewhere on this site, which were made in my much smaller work room.  The first set of measurements is for the JMLab Mezzo Utopia, a tower design with a the W series woofer and mid-woofer, and Focal's top-of-the-line inverted dome tweeter.  The sound is quite clean, wide range, and very detailed in the highs.  In my initial listening tests, brass instruments were slightly smeared and there seemed to be a slight discontinuity above the midrange.  Here is a one-meter on-axis plot taken on the tweeter axis:


Here is the room response, showing excellent bass extension, but also highlighting the moderate problems in the midrange around 1 kHz.

The following measurements are for the mega-buck Westminster Royals, Tannoy's top-of-the-line speaker.  The tweeter is concentrically mounted deep inside the 15" woofer, and the woofer is loaded by an elaborate folded horn below 250 Hz.  This monster is extremely sensitive (93 dB), and intended for a huge space.  I'm not sure my simple short-range measurements mean very much, other than to point out possible broad areas of elevated or depressed response.  Cancellation effects are inevitable given the position of the tweeter and the elaborate wood-paneled horn-shaped baffle.  In any event, here is the on-axis response, taken at a little over one meter:

And here is the room response:

I did not get much chance to listen to the Royals.  I thought I detected a slight hollowness in the lower midrange, and some added warmth a little lower down.  These impressions are consistent with the measurements showing elevated response in the 300-400 Hz range.  I didn't hear any problem in the highs.  In any event, I'm not sure ruler-flat response is what these machines are all about.  They are obviously intended to recreate certain aspects of a live performance smaller, more conventional speakers can't manage.

Here are the measurement for the VMPS RM1 tower speaker, which uses two 8" woofers crossed to a midrange ribbon, and then to a circular super-tweeter ribbon.  The woofers are loaded by a passive radiator.  The only sound I got to hear coming out of these speakers was the test signal, and it contained a much higher midbass content than I've encountered before.  The on-axis measurement is taken with the tweeter level set near its maximum, and the midrange level at about 70 percent.  The deep notch above 12 kHz may be a cancellation effect from two foam strips on either side of the tweeter.

And here is the room response, which indicates a passive radiator tuning problem.  The owner commented that the speakers sounded heavy to him.

To provide some frame of reference for the measurements in the new room, I also measured the bookshelf monitor I had designed for the owner of the Tannoys and JMLabs.  These monitors use a Skaaning 6" Flex series woofer and the Morel Supreme dome tweeter.  The woofer also showed a moderate peak around 1 kHz in my measurement room.  (This minor problem was not fully addressed in the design in order to keep the crossover simple enough to fit in the cabinets.)  Here is the on-axis response:

And the room response.  (The rise in the deep bass is not due to any miraculous performance capabilities of the Skaaning woofer -- that's a patio door sliding open.)

Although the little monitor lacks the dynamics and bass response of the JMLabs, the owners of both the JMLabs and the VMPS did report that the Skaaning-Morel combo was noticeably smoother, and, in comparison to the VMPS, more detailed.