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 Peerless DX25TG09-04 (Vifa XD-270 F / 4) at Waveguide WG-300 4 Ω dome tweeter with waveguide

Datasheet © www.heissmann-acoustics.de
Measurements in 20x40cm baffle, 10mm rounded, in 70cm distance at 2,83V. Level scaled to 1m.

The Waveguide was milled with a CNC adapter plate mounted on the tweeter.

Vifa XD270F4 WG300 closeup

Directivity horizontal (0-90 ° in 15 ° steps)

Vifa / Peerless XD-270 F / 4 (DX25BG60-04) on Waveguide WG-300

Due to the waveguide system-related symmetrical elevation in the frequency band of 1-10kHz. This can be easily leveled with the crossover.

The Vifa Peerless XD-270 / F4 fits perfectly with the Waveguide WG-300. Very uniform bundling without significant interference. Outstanding is the behavior> 10kHz. 20kHz are reached even under 45 ° with almost full level.

The amplitude response drops below 45 ° of 2-18kHz by only 2,5dB! The 30 ° curve runs to 20kHz in a + -1,5dB tight tube. 20kHz are reached at full level.

The sonogram shows a bundling behavior that comes very close to the so-called Constant Directivity.

Sound pressure standardized at angles to 0 °

Vifa / Peerless XD-270 F / 4 (DX25BG60-04) on Waveguide WG-300

Vifa_XD270_WG_Sonogram_normiert

Burst decay

Minimal delayed decay by 2 and 20kHz. Otherwise perfectly.

Harmonic distortions

Vifa Peerless XD-270 / F4 (DX25BG60-04) & Waveguide WG-300 harmonic distortion

The harmonic distortion of the XD-270 F / 4 on the waveguide is excellent.

K2 remains below the 100% mark even at 1,2dB as of 1kHz. K3 moves from 1kHz between 0,04 and 0,3%.

Clatter components of higher order are in the (for me) no longer measurable range.

Separations from 1,2kHz are possible without hesitation, depending on the application and level requirements possibly even deeper.


Rating


Frequency response / directional behavior:5 5 out of stars
Range:5 5 out of stars
Power handling:5 5 out of stars
consisty:4.5 5 out of stars
Haptics:4 5 out of stars
Price-performance:5 5 out of stars

Summary


The Peerless / Tymphany DX25TG09-04 on the Waveguide WG-300 measures itself outstanding.

The ability to build a speaker that comes close to the specifications of Constant Directivity. Separations from 1,2kHz. Lowest harmonic distortion even with 100dB / m ...

Of course, a very interesting driver for Cinetor.

CNC adapter plate for various Scan-Speak and Peerless tweeters on WG-300 and PCT-300

From the houses Scan-Speak and Tymphany, there are some tweeters, all sharing the same front panel. One or the other of them is also outstanding on the P-Audio (PCT-300), or Monacor (WG-300) waveguide. In order to connect the drivers cleanly with the sound conduction, a CNC machined adapter plate was created after many test series, which allows a simple and very precise fitting.

If you have access to an 3-D printer, you may like to download the following file and print out the adapter plate.

⇒ Adapter plate as STL file⇐

The following tweeters are suitable for the conversion

The first ones were rebuilt by me and measured with very good, partly outstanding results. The following all share the same front panel and are, at least extremely similar to one of the measured drivers ... .and there are a few more potential candidates.

Construction of the adapter plate with "home remedies"

Only a few of us own a CNC milling machine. To build such a simple construction as this adapter plate, there is no need for anyone! With jigsaw, cordless screwdriver, router and the following step-by-step instructions, the construction of the adapter plate should not be a problem. It does not even have to be measured 🙂 Let's go ...

  • Download PDF (click on the picture)

  • Print out with Acrobat Reader (select option "actual size"!)
  • Size check: Outer diameter 120mm
  • Stick on a 9mm strong piece of MPX / MDF / screen printing plate (spray glue / glue stick ...)
  • The drilling holes => drill press is an advantage!
  • With the circular milling device (each speaker should have one) 3mm deep to appropriate mark milling (D67mm)
  • Use the jigsaw to saw the inner hole and saw off the plate in the last step

From the practice with the "home remedy method" another supplementary tip from Thorsten (www.felbi.at)

If you glue your artwork directly onto the substrate (eg MPX), you will have the difficulty to get it down again later. For visual reasons, that bothered me and came up with the following idea: Before you glue your artwork on the MPX, just past the MPX with tape. Now the artwork will be cut to the size of the MPX board. Spray glue is then sprayed onto the package tape and allowed to dry for about 5 minutes (Note the spray adhesive is not on the paper spray!). Now the print template can be glued on.

Once all drilling and milling work has been completed, the package strap can easily be pulled down again from the MPX board.


Assembly

First, the front panel of the tweeter must be removed. On some models, this is easily fixed with a silicone-like adhesive. In this case, with a large flat-head screwdriver discreetly "lever" as shown in the following picture. Work slowly and evenly. In advance, of course, the screws of the front panel should have been solved (TX10).

Dressing the waveguide neck

The adapter plate is placed on the sound guide and the neck is ground flat with circular movements (⇒ dust mask).

The following video shows the final montage

Contrary to the indication in the video no M3x16mm, but M3x12mm Screws used! The M4x10mm are welcome, but they do not have to be longer.

Finally, two shots of the Scan-Speak D2604 / 833000 or 830000 & the Peerless XT25TG30-04 with waveguide

Disclaimer

You do the conversion on your own responsibility! I accept no liability. Possibly. you lose your warranty claims during the conversion.

I did a lot of conversions and nothing ever happened. I think the manual is pretty foolproof 🙂

... coffee is available from 1 € 😉

Test Peerless / Tymphany XT25TG-30 / 04 (XT-300 / K4) at the waveguide WG-300 / PCT-300 4 Ω ring emitter with waveguide

Datasheet © www.heissmann-acoustics.de
Measurements in 20x40cm baffle, 10mm rounded, in 70cm distance at 2,83V. Level scaled to 1m.

The Waveguide was milled with a CNC adapter plate mounted on the tweeter.

XT25TG30_04_WG

XT25TG-30 / 04 Sound pressure at angles

Vifa XT-300 (XT25TG-30 / 04) WG300 Sound pressure at angles

System-induced overshoot in the frequency band of 1-7kHz. This can be due to their symmetry very easy to equalize with the crossover. It is the purpose of a sound guide to act as an acoustic amplifier. This results in a more uniform bundling and higher load capacity. The Vifa XT-300 (XT25TG-30 / 04) fits perfectly with the waveguide. Extremely uniform bundling without significant disturbances. Due to the large dome (30mm voice coil) slightly stronger directivity from 8kHz.Recommendation: On the axis a slight increase> 8kHz in the tweeter schedule.

XT25TG-30 / 04 Sound pressure standardized at angles to 0 °

Vifa XT-300 (XT25TG-30 / 04) WG300 Sound pressure normalized at angles

Vifa XT-300 (XT25TG-30 / 04) WG300 Sound pressure normalized at angles

Here, the frequency response was linearized on axis. The 2. Picture (sonogram) clearly shows the excellent uniform straightening behavior of the combination of XT-300 and the waveguide.

XT25TG-30 / 04 decay behavior

Vifa XT-300 at Waveguide WG-300 decay behavior

Minimal delayed decay by 2kHz. Otherwise perfectly.

XT25TG-30 / 04 harmonic distortions

Vifa XT-300 at the waveguide WG-300 harmonic distortion

As expected, the distortion decreases compared to the variant without waveguide. The XT-300 already showed very good distortion even without waveguide, but with a significant increase of K2 under 3kHz. With Waveguide the effect is also present but attenuated by about 5dB. In sum, very low distortion. Even with 100dB, everything from 2kHz remains below 1%. K3 moves at the measurable limit.

Rating


Frequency response / directional behavior:4.5 5 out of stars
Range:5 5 out of stars
Power handling:5 5 out of stars
Constance / Without Rating /:0 5 out of stars
Haptics:4 5 out of stars
Price-performance:5 5 out of stars

Summary


The Peerless XT25TG-30 / 04 and the Waveguide WG-300 are a highly attractive combination for extremely low-level installations, eg in home cinema. Can be used already from 1,5kHz. I think I'll test that in Cinetor.

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.