Zaph|Audio

Battle of the Non-Domes

Featuring:

Aurum Cantus G3Si ($213)

LCY 130 ($199)

Fountek NeoCD2.0 ($118)

Bohlender Graebener Neo3 PDR ($55 w/flange)

Silver Flute YAG20-1 ($40)

Special Guest Performance by:

Vifa D26NC55 ($29)

Initial posting - December 1, 2005
Minor update and corrections - December 14, 2005
Line array comments and minor updates - December 30, 2005

About the Test

This test is divided up into 3 sections - Standard tests, Extended tests and Comparisons.

The standard tests consist of frequency response, cumulative spectrum decay and harmonic distortion sweeps. The results of these tests can be directly compared to the results in the Tweeter Mishmash collection of dome tweeters. All settings are the same. Please see the test information on that page for more details on the testing setup. Because the Vifa D26NC55 is accurately described in the Tweeter Mishmash, it is not included in this section with one small exception. The exception is the harmonic distortion sweeps, where it has been included, but this time with the same protection capacitor used on all the ribbons and planars.

Another difference from my previous tests is that the vertical off axis is shown at 15 and 30 degrees. While practically all 1" dome tweeters have similar off axis response, this is a critical consideration for the taller ribbons and planars. Note that horizontal dispertion for all of these tweeters is excellent, and very close to the on-axis response curve. Because of this, only vertical off axis is shown and not horizontal.

A 20uF capacitor is used on all tweeters for all tests. Ribbons in particular are very fragile, and they have an impedance that droops to zero at DC. Because of this, a capacitor is required to prevent damage. Additionally, ribbons require careful observance of levels and amplifier clicks and pops.

The effects of the capacitor are not visible in the frequency response curves and cumulative spectrum decay charts. The capacitor is placed between the amplifier and the speaker on the positive terminal, but there is no effect because the testing probe is placed after the capacitor. Harmonic distortion however, is based only on the actual reproduced level of the fundamental, and the 20uF cap causes a rolloff of a few dB at 1kHz. In reality, the harmonic distortion sweeps in the range around 1kHz are just a bit higher than shown in these tests. The Vifa D26NC55 has been included to show this.

The extended tests are single tone and multitone spectrums. These show a slightly more indepth look at what's going on higher in the spectrum. At the same time, there is less information there because the tests are limited to 2kHz and 4kHz. Single tone spectrums show all the harmonics above F5. The multitone tests show a bit better glimpse into intermodulation distortion than the harmonic distortion sweeps do. Ribbons seem to be more varied in this regard, so I've included this kind of testing. In all of these tests, the fundamental frequency is set to 96 dB at 1/2 meter. Disregard the decible markings on the charts - the vertical chart increments are not 10dB per line. Look at the spectrum performance relative to the other plots. The Vifa D26NC55 is included in these tests for a reference of a good performing cheap standard dome tweeter.

The comparisons take a few select combinations of tweeter multitones and lay the better performing tweeter on top in a different color so the difference can easily be seen. Without these comparisons, it's a little hard to digest and compare all the info in the extended tests. In these plots, wherever you see red is comparitively more spectrum noise. The lower blue plot is generally the better driver. In some cases, the comparison may be shown twice with the layers inverted if the performance is too close to call. The Vifa D26NC55 is also included in these tests for a reference of a good performing cheap standard dome tweeter.

Results:

Standard tests

Extended tests

Comparisons

Commentary

Aurum Cantus G3Si ($213) - Of the three true ribbons, the G3Si has the best low end performance. This isn't saying much since low end distortion is still horrible by dome standards. High tall order harmonic distortion, which is more evident in the single tone spectrum plots. Poor vertical off axis response. While the faceplate is metal, I still consider the build quality lower than the Fountek or LCY.

LCY 130 ($199) - Very low sensitivity. Excellent vertical off axis response. Very close in on-axis performance to the Fountek, but at a much higher price. Good built quality - You have to like red and black jewels on the terminals to designate positive and negative. One of my test samples had a misaligned ribbon, but it did not affect things so I assume it was not touching the magnets.

Fountek NeoCD2.0 ($118) - Comparitively durable ribbon element. Of the three true ribbons, this has the best performance above 4kHz. It has the worst performance at 2kHz, rendered somewhat irrelevant because they are all terrible at 2Khz. It's excellent 4kHz+ performance is more obvious in the HD sweeps than the single and multitone spectrums however. Smooth response curve. Poor vertical off axis response.

Bohlender Graebener Neo3 PDR ($55 w/flange) - This B&G tweeter outperformed everything here, in most cases by a large margin. Response curve is ok, but nonlinear distortion is excellent. This is a very clean and natural sounding tweeter. Note: these were tested with the rear chamber in place. Later, with a different pair, I also tested with the chamber removed. The tweeter was far too overdamped in that case, and I recommend leaving the rear chamber installed.

Silver Flute YAG20-1 ($40) - Every test has to have a loser. This is it. Fairly flat and controlled response, but the distortion kills it. In fact, it may be the worst tweeter I've ever tested.

Vifa D26NC55 ($29) - This cheap little dome tweeter outperforms everything here except for the B&G Neo3 PDR in the non-linear distortion department. It works well at 2kHz like the B&G, but has ever so slightly higher HD everywhere else. On the other hand, this tweeter beats the Neo3PDR in response smoothness and the resulting smooth CSD. (full results shown in the Tweeter Mishmash)

A Bit About Line Arrays

These tests do not address usage of ribbons stacked in line arrays. A line array will spread the load among several drivers, which will lower harmonic distortion. When the level of a tweeter is lowered, the harmonic distortion is also lowered. This in itself does not help the level of distortion, but the ratio of the level of harmonics to the level of the fundamental does not remain linear at different levels. So, as the level goes down, the harmonics also go down, but a little bit more. This is where the improvement in harmonic distortion comes from.

Don't assume stacks of ribbons in line arrays lower distortion to levels equal to the better dome units. Evidence of that will have to wait until it's proven with actual measurements. Ears can not be trusted to make a distortion measurement, particularly when there is an emotional $5k price tag interfering with your judgement.

A note about power tapering - a stack of ribbons in a power tapered arrangement will have much more distortion than a stack of ribbons wired so that they all share the load evenly. Power tapering is simply a method to bring the design closer to a point source, which unfortunately has the side effect of bringing the distortion closer to the level of a single tweeter. How much closer simply depends on the tapering configuration.

Summary

None of the three true ribbons have very distinguished performance. They are more similar than different. But if I had to choose one, it would probably be the Fountek NeoCD2.0 because of it's durable ribbon, smooth response and clean top end performance. I'm not sure if I could live with that vertical off axis response, as I occasionally don't like to be locked in to sitting ear height. Generally, these ribbons do not live up to their price and hype. This point is driven home by their comparison to the cheap little Vifa neo dome.

None of the true ribbons, when used one at a time, should be used below 2.5kHz. The higher you cross them, the better you will avoid low end distortion. On the other hand, these are all large flanged tweeters, and as you cross higher, lobing at Fc becomes worse.

I often hear people babble on about the shimmer, sparkle and air of ribbon tweeters. These tests show where these "special effects" are coming from - distortion. Ribbons do have a unique distortion profile that many will find enjoyable with some music. That's OK, and it does not have to relfect badly on your "golden ear" status. However, if accuracy to the original signal is what you are after, one of these ribbons may not be the best solution. Ribbons are certainly not the best solution if you want to build a high-value system. Those building line arrays may want to take a good hard look at one of the longer B&G elements.

The B&G and Silver Flute are both planar designs, but they are also polar opposites. The YAG20 is probably one of the worst performers I've ever seen, while the B&G performs on level with the best domes. It's hard to say what went wrong and what went right in their designs.

Folks, we have a winner - The Bohlender Graebener Neo3 PDR.

Zaph|Audio

Battle of the Non-Domes

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