Modification of the tweeter Monacor DT-300, according to Klang & Ton 6 / 14

A customer request, whether in the sound and sound 06 / 14 (kit MonaLisa, developer Ronald Waßen) presented modification of the tweeter DT-300 synonymous in the Cinetor meaningful, I took the opportunity to perform this.

DT300_klang_und_ton_mod

In the modification, the ferrofluid is removed, introduced into the Polkernbohrung insulation wool and glued a felt ring on the pole plate. A detailed guide can be found in the Sound and sound forum.

The metrological results

All measurements were made with Waveguide, in 20cm narrow baffle.

frequency response

DT300_klang_und_ton_mod_ampSignificantly extended frequency response towards lower frequencies. Minimal higher efficiency, otherwise practically congruent course.

impedance response

DT300_klang_und_ton_mod_impSignificant influence of the modification on the impedance response. Clean and balanced impedance peak at 800Hz (blue). Compared to before (black), with clearly flattened course and 3 impedance bumps (Some DT-300 show only a double bump). In order to achieve a really clean and symmetrical impedance peak after the removal of the ferrofluid, the pole core bore has to be stuffed quite firmly with insulating wool. Effectively, the pole core bore was acoustically sealed by a 14x3cm long strip (blue). In comparison, (red) stuffed a little less, with a strip of 7x3cm. The "new" impedance path allows much deeper separations, so the distortion measurements should not oppose ...

Harmonic distortions

DT300_klang_und_ton_mod_dist... and you do not do it. No increased harmonic distortions. K2 between 800Hz and 2kHz even slightly lower. Separations to 1,5kHz, possibly even deeper should now be feasible!

Burst decay

DT300_klang_und_ton_mod_bdSlightly improved decay behavior around 7, - and 13kHz.

Meaningfulness of the modification of existing systems

DT300_klang_und_ton_mod_weicheThe example shows a separation by 2kHz with 18dB / Oct. Dashed without, solid with modification. The frequency response in the work area shows small deviations, however, the slope changes to the midrange, which can have a negative effect on the overall system. At this point it is therefore not possible to give a blanket "blessing" regarding the modification of existing systems.

Conclusion:

The modified DT-300 is the better DT-300. Significantly more beautiful impedance, more separable, more even decay, and minimally balanced in super high tone. Negative effects could not be determined.

Finally:

The modification should not be done without control measurements. A simple impedance measurement, which can be realized with the free version of LIMP (part of the ARTA Family) and a material usage of 1-2 €, is completely sufficient.

Reasons:

It should be ensured that the voice coil is still well centered after the modification. There are a few factors that influence it.

  • She was not there before
  • The tightening torque of the screws
  • Possible game in the forced centering
  • The positive centering allows two mounting positions, which can lead to different results

Ferrofluid can compensate for small errors in the centering of the voice coil. It could happen that one, just before the modification just enough central voice coil, grinds or hangs after the mod at the air gap.

Test Monacor DT-300 with Waveguide WG-300 A combination for high level applications with very good directional characteristics

Datasheet © www.heissmann-acoustics.de
Measurements in DIN baffle in 70cm distance at 2,83V. Level scaled to 1m

Monacor DT-300 with Waveguide WG-300

30mm dome tweeter with waveguide

DT300_WG300

Monacor DT-300 / WG-300 sound pressure (scattering)

Monacor DT-300 & WG-300 amplitude response dispersion

Monacor_DT300_WG300_Streuung6

Monacor_DT300_WG300_Streuung3

Due to the principle, the frequency response drops evenly towards high frequencies (waveguide), which is very easy to equalize with the crossover. Noteworthy are the two burglaries at 7kHz and 13kHz.

Overall satisfactory dispersion. From 2-14kHz all 4 DT-300 / WG-300 move in a hose of + -1dB, above and below a little worse.

Addendum: As for the Kits Cinetor and Cinetor HWG, the tweeters have been individually checked for quite some time now, I have several serial measurements of the DTXNUMX on the waveguide.

The 2. Picture shows an example of relatively high, the 3. of very low consisty.

Monacor DT-300 / WG-300 Impedance (Scatter)

Monacor DT-300 / WG-300 Impedance

The impedance curve of the DT-300 with WG-300 is not very harmonious and of relatively low consisty.
The differently pronounced double hump probably originated in different damping of the pole core bore to the coupling volume and in the extremely generous dose of ferrofluid. Separations below 2,5kHz are only conditionally recommendable.

Monacor DT-300 / WG-300 sound pressure at angles (0-90 °)

Monacor DT300 WG300 angle measurements
Directional behavior is very uniform, thanks to the waveguide concept.
The bundling behavior <= 2kHz results from the narrow baffle (20cm). Only at angles> = 45 ° is the frequency response above 10kHz somewhat restless. Altogether the Monacor DT-300 and the Waveguide WG-300 harmonize well with each other.

Monacor DT-300 / WG-300 decay behavior

Monacor DT-300 / WG-300 decay behavior

Overall smooth and fast decay, delayed by 7kHz and 13kHz.

Monacor DT-300 / WG-300 harmonic distortion

Monacor DT-300 / WG-300 harmonic distortion

The Monacor DT-300 on the WG-300 has very low harmonic distortion. K2 rises evenly with the level and always stays at a low level. K3 only rises below 2kHz, above that extremely low. Harmonic components of higher order are negligible. From the harmonic distortion one could disconnect the combination DT300 / WG300 without hesitation at 1,5kHz. Unfortunately, the impedance gear is in the way.

Rating


Frequency response / directional behavior:4 5 out of stars
Range:4 5 out of stars
Power handling:5 5 out of stars
Consisty:1.5 5 out of stars
Haptics:3 5 out of stars
Price-performance:2 5 out of stars

Summary


The Monacor DT-300 with the Waveguide DT-300 is on the whole a good tweeter. In particular, the level stability, the high efficiency, the low harmonic distortion and the uniform radiation behavior under angles are to be emphasized.

Big downside is the lack of constancy of the driver.