Modification of the Monacor DT-300 tweeter, 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.


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 symmetrical impedance peak at 800Hz (blue). Compared to before (black), with a clearly flattened course and 3 impedance bumps (some DT-300 only show one double bump). In order to achieve a really clean and symmetrical impedance peak after the ferrofluid has been removed, the pole core hole must be tightly stuffed with insulating wool. The pole core hole was effectively closed acoustically by a 14x3cm long strip (blue). Compared to this (red) a little less stuffed, with a 7x3cm strip. The "new" impedance response allows significantly deeper separations, so the distortion measurements should not prevent this ...

Harmonic distortions

DT300_klang_und_ton_mod_dist... and you don't. No increased harmonic distortion. K2 between 800Hz and 2kHz is even slightly lower. Separations around 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 of 2kHz with 18dB / oct. Dashed without, solid with modification. The frequency response in the working range shows slight deviations, but the slope changes towards the mid-bass, which can have a negative effect on the overall system. It is therefore not possible at this point to give a blanket "approval" for the modification of existing systems.

At the end...

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.


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.


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 ©
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 goes perfectly with the waveguide WG-300. Very even bundling without significant disturbances. The behavior> 10kHz can be described as outstanding. 20kHz are reached even below 45 ° with an 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


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.


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


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

The possibility of building a loudspeaker that comes close to the requirements of constant directivity. Separations from 1,2kHz. Lowest harmonic distortion even at 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

There are some tweeters from Scan-Speak and Tymphany, all of which share the same front panel. One or the other of them also measures itself excellently on the P-Audio (PCT-300), or Monacor (WG-300) waveguide.

In order to connect the drivers cleanly with the sound guide, an adapter plate milled in CNC was created after many test series, which allows simple and very precise installation.

The following tweeters are suitable for the conversion

3D printed adapter plate in the shop

Construction of the adapter plate with "home remedies"

With a jigsaw, cordless screwdriver, router and the following step-by-step instructions, building the adapter plate yourself should not cause any problems. It doesn't even have to be measured 🙂 Let's go ...

  • Print out the PDF (included in the respective building folder) using Acrobat Reader (choose the “actual size” option!)
  • Size check: Outer diameter 120mm
  • Glue on a 9mm thick piece of MPX / MDF / screen printing plate (spray glue / glue stick ...)
  • Drilling the holes => upright drilling machine 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 additional tip from Thorsten (

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.


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, use a large slotted screwdriver to "pry" it up discreetly as shown in the following picture. Work slowly and evenly. The screws on the front panel should of course have been loosened beforehand (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).

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


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

I made a lot of changes and nothing ever happened. I think the instructions are pretty "foolproof" 🙂

The plans of the adapter plate are the intellectual property of, Alexander Heißmann. Any transfer requires my express consent.

... you can get a coffee 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 ©
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.


XT25TG-30 / 04 Sound pressure at angles

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

System-related exaggeration in the frequency band of 1-7 kHz. Due to its symmetry, this can be easily equalized with the crossover. It is the purpose of a sound guide to act as an acoustic amplifier. The Vifa XT-300 (XT25TG-30/04) is an excellent match for the waveguide. Extremely even bundling without any disturbances worth mentioning. Due to the large dome (30mm voice coil), a slightly stronger directivity from 8kHz. Recommendation: plan a slight increase> 8kHz in the high frequency on axis.

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.


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


The Peerless XT25TG-30/04 and the Waveguide WG-300 are a very attractive combination for extremely level-stable installations, for example in the home theater. Can be used from 1,5 kHz. I think I'll test it out in Cinetor.

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

Datasheet ©
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


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

Monacor DT-300 & WG-300 amplitude response dispersion



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 ° does the frequency response become somewhat unsteady above 10kHz. 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 distortions. K2 rises evenly with the level and always remains at a low level. K3 only rises below 2kHz, above it extremely low. Higher order distortion components are negligible. From the point of view of the distortion values, the combination DT300 / WG300 could be separated at 1,5 kHz without hesitation. Unfortunately, the impedance curve stands in the way.


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


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.