What is on the test bench?
Today we wil get familiar with Wavecor TW022WA05 tweeter.
TW022WA05 is a 22 mm fabric dome tweeter having ferrite magnet motor and light wavegude loading for some controlling of sound pattern. Of all features we should note very low resonance frequency for a tweeter with such small membrane size - 760 Hz, not all products on the market can boast by such a figure. As stated by the manufacturer, 22 mm size is choosen as a reasonable compromise between 19 mm and 25 mm models, having combined in itself a wide sound dispersion which is attributable to 19 mm domes and low resonance frequency which is often can be seen in 25 mm dome tweeters.
After a little digging in the web we have discovered appearing of this tweeter in the products of such companies as Penaudio (Finland) and Audio Physic (Germany):
You can get familiar with the Wavecor company history here.
Why do we test this?
The speakers of the Wavecor company have been long attracting our attention with its construction, innovate technologies, Danish roots and quite flattering feedback from consumers. However, for some reasons they couldn't reach us. At last, at the Munich exhibition Hi-End Show 2018 we had the opportunity to personally meet at the Wavecor stand with Allan Isaksen, the general manager of the company, and got to touch to the significant part of the Wavecor speaker model range. Allan Isaksen made us the impression of a business and punctual person and kindly agreed to provide several models for independent testing, for what we express our gratitude to him.
What did the manufacturer state?
We are looking in the oficial technical datasheet:
The first to note is a perfectly designed document - a triffle but very pleasurably. We think, taking in account fullness of information, design and convenience of displaying graphic information (correctly selected scales of axes), the Wavecor's datasheets could be serve as a reference for other companies . As many loudspeaker designers, seeking for speaker drivers for their projects, are orienting, first of all, on the official datasheet, then they will not be disappointed here.
There is nothing to comment here, the manufacturer's words say for itself.
Of numerical parameters especially should be noted the declaring of additional parameters as Krm, Erm, Kxm and Exm for advanced TSL speaker driver model, that give an oportunity to designers to model a tweeter operation much more precisely. The resonance frequency is 760 Hz and it is really very low for a tweeter of that voice coil size. In conjunction with Qts=1.08 it gives very extended frequency response in low end - down to 600 Hz by the -3 dB level. Sure, nobody should use a tweeter to a such low frequency but an extended low end helps in joining the tweeter with lower band speaker.
Tweeters having "-01" suffix in the part number are supplied each in an individual box. The box of dense cardboard with formatted inserts made of foamed polyethylene provides very reliable transportation.
We should note absolutely perfect manufacturing quality of the product - no mechanical defects, no scratches, no chips on ferrite magnet, no burrs, perfectly glued label, perfectly aligned foam gasket (what is not always happens in much more expensive tweeters!). Nothing bends and does not creak, the tweeter is felt in the hands, as a single monolithic product. The front flange has a fine texturing and is made of a very hard and strong plastic. The plastic is so durable that the question immediately arises - should it necessarily be metallic? Exactly not in this construction. The back plate is painted black (it should be noted that in all Wavecor models all metal parts are painted black), which provides an improved heat dissipation due to the radiation effect. The measured mounting flange diameter and thickness are turned out to be exactly the same as in the datasheet, therefore, you can safely trust to datasheet mechanical drawings.
The terminals are gold-plated but slightly clunky. If you plan to connect to them using soldering, then there are no problems, but with knife terminals you need to be more careful. The mounting flange diameter is 103.75 mm - for a tweeter with such a small dome it could be benefit to have a little bit lower diameter to reduce the center-to-center distance to a lower band driver.
The ideal quality of manufacturing testifies to a very high production culture and a serious attitude of the company to the quality of its products.
Impedance frequency response
You can see impedance frequency responses for two samples and it is remarkably - the tweeters are delivered by the piece, not a matched pairs, but the curves lie each on other so way we can't see one behind the another. The measured resonance frequencies are - 755 and 762 Hz and Qts - 1.082 - fully match with datasheet's parameters. Excellent consistency! The impedance curves are very smooth without any signs of parasitic resonances in the whole frequency range. Slightly increasing with frequency, the impedance indicates rather the absence of short-circuiting rings in the magnetic system.
The measured on-axis magnitude frequency response differs from the datasheet's one. The response from the datasheet is slightly wriggling, but monotonously goes up with an increase in frequency, while in the measured one there is a smooth rise in the range from 2 to 7 kHz and then return to a flat character. The lower end is also not as extended as in the specification. In general, the SPL frequency response is fairly flat and the deviation from the mean value of 90 dB (at voltage 2.83 Volts) in the 700 Hz - 28 kHz range does not exceed a plus/minus 2 dB, what is a very good number for a fabric dome tweeter. The measured averaged sensitivity is 90.7-91 dB, which is slightly lower than the declared sensitivity (91.5 dB).
Off-axis frequency responses
The off-axis responses behavior demonstrates a uniform and smooth decrease with increasing angle of deviation from the main axis and well agrees with those ones from the specification. The decay of the frequency response up to 16 kHz, even at angles of deviation of 60 degrees does not exceed 11 dB, which is very good!
Harmonic distortion (315 mm)
We give distortions at an average sound pressure level of about 94 dB and can characterize nonlinear distortions as "average". The mark could be higher if were wouldn't exist increased level of the third harmonic, although the levels of the 2nd, 4th and 5th harmonic distortion are rather low for a 22 mm dome tweeter.
The step response demonstrates an excellent slew rate due to the very extended top end, and a rapid and smooth decay. Return to the resting state is not so fast, crossing the rest line a couple of times - a consequence of the low resonance frequency and its high Qt value. When used in real systems with the cutoff frequency of 2.5 kHz, you can ignore it. The teeth in the falling part of the curve are determined by the features of the measuring system and in this case are not related to the tweeter.
The waterfall diagram shows a good rapid decay of the transient process in the absence of any parasitic resonances. Very good!
We can tell about our listening impressions only after testing the tweeter in real loudspeakers. Since we have not yet reached this point, we will leave this report for later.
This section will be updated after a real test in loudspeakers.
"How to use" recomendations
It is recommended to use these tweeters in two and three-way speakers in the frequency range from 2.5 kHz and higher. Measurements of nonlinear distortions confirm the validity of the manufacturer's recommendation.
What is price and where to purchase?
The average retail price of TW022WA05 tweeter is about 51 EURO (VAT not included).
It can be summarized that the testing confirmed the very close correspondence of the measured parameters with the claimed ones, except for the frequency response. The tweeters have the following features:
You can find more measurements of this tweeter here.