DXT-MON vs. Neumann KH-120A ... or "How far can I get with DIY and where are the limits"

kh_120a_vs_dxt_mon_1240Once the following question was asked in the hifi forum:

"How far can I get with DIY and where are the limits?"

The "critical question" was whether it would be possible to top or equal the active monitor KH-120A, presentet by Neumann, with a budget <= 1300 € / pair / active, what was the price of the KH-120A, with comparable dimensions.

Well, the thread ran for a long time, it was discussed intensely, argued but also worked constructively. If you are very interested in the whole story, you may want to read the thread in the forum, but we can also make it short:

DXT-MON is the only construct arose from this thread that was succresfully finished, and complied with the conditions of the Battle, and was developed with the aim to outperform the Neumann KH-120A. To clarify whether this finally succeeded or not is the aim of this article. Of course it is not easy for me, as a participant, to make an objective judgment. But since there is no comparison of these two speakers, except the one I've done, there's nothing left for me to try anyway ...

In the following now the comparison of the two speakers. All measurements were made under identical conditions. Nothing was whitewashed, added, or poised. The pair DXT-MON was activated with a Hypex AS 2.100 module. There were no filters set. The measurements are shown in animated GIFs, with picture changes every ~ 3 seconds between the two speakers.

Directivity horizontal

Frequency response 0-90 ° in 15 ° steps

Both speakers have a very uniform horizontal dispersion. DXT-MON tends to be broader. In terms of balance, in my opinion, none of the two are considered better => draw at a very high level!

At this point, the topic "linearity" may also be dealt quickly:

without big words: draw

Directional behavior vertical


It gets a bit more difficult because both candidates have inherent weaknesses. Both show a cut-off at the crossover frequency and a sidelobe at 3kHz below ~ 30-60 ° down. For the DXT-MON it is a bit more broadband, on the other side the KH-120A shows a longitudinal resonance of the BR channels (at 1,5kHz). I would be inclined to attach a little more importance to longitudinal resonance, it would anyway call it a draw .

Harmonic Distortions (90dB / m & 100dB / m)



DXT-MON has slightly higher 2. order distortions below 400z, on the other side, in the same area, (at 90dB / m significantly) lower 3. Order distortions. 4. Order distortions are almost equal between both. DXT-MON is less impressed by the volume change between 90 and 100dB / m. This, along with the lower 3. order distortions, makes the DXT-MON the tight but deserved winner in this discipline. + 0,5 points for DXT-MON

Passive membrane vs. BR channels in front

dxt_mon_kh120_nahfeld_vglThe developers of the KH-120A have managed to circumvent the usual problems of front-mounted BR channels as far as possible. This has been achieved, for example, by providing foam-filled slots in the channels, thereby "smearing" spill effects and equalizing them to the tuning frequency. Nevertheless, the longitudinal resonance at 1,5kHz still strikes with ~ -16dB, which is particularly noticeable in the measurements downwards, eg. towards the tabletop, shows. Also, the bass reflex channels still contribute to over 300Hz to the overall action.

In return, the passive membrane works on the DXT-MON as it should. No annoying resonances, no midtone components, from no later than 300Hz the TMT works practically alone, to it was no equalization, which has a negative effect on the group delay, needed to achieve the desired draft ... + 1 point for DXT_MON

Adaptability / Flexibility

With the KH120A you can ...

kh120_a_maeuseklaviaturmake the following settings:


For this purpose, a limiter can be set. This works extremely practical, fast and reliable. Very good!

With the DXT-MON, a Hypex AS 2.100D with integrated DSP ...

AS 2.100DSource:

... virtually everything can be adjusted. For standard corrections, such as the 4-level acoustic control for bass, low-mid and treble of the KH-120A, there is no need for measurement technology.

AS_2_100_filter designer

Neumann KH-120A: Easier and faster with, usually sufficient possibilities

DXT-MON: Significantly extended possibilities with more complex operation

⇒We call it draw.


Neumann KH-120A DXT-MON
Kit including tree cap: ~ 265 € / piece
Hypex AS 2.100D: ~ 250 €
1300 € / pair ~780 € plus housing / pair


There is not much between DXT-MON and the Neumann KH-120A. Both measure themselves exceptionally well in practically every respect, taking into account given physical limits. Nevertheless, I could not help but to come to the following conclusion:

The passive diaphragm, and the outstandingly good WF152BD06 are, in the author's point of view, the tip of the scales towards a tight but deserved victory on points for DXT-MON.

... feel free to write me your opinion in the comments

6 thoughts too "DXT-MON vs. Neumann KH-120A ... or "How far can I get with DIY and where are the limits""

  1. I am new to speaker DIY, and trying to understand this a bit more.

    On the Heismann website there are two designs for DXT-MON, one with a passive radiator and another with a port. IIRC. Both of these designs are passive monitors (with passive crossover kit parts IIRC), with no specification of any amp.

    Which one of the versions of DXT-MON is compared to the Neumann KH120's?

    If I wish to build the same version of the DXT-MON which has been favorably compared with the KH120, in this review, exactly what would I need to order, and from which company?

    Will by DIY effort just do the assembly of the kit, or do I therefore need to build the wooden case myself?

    Is there any provision in the wooden case for mounting the hypex amplifier (eg cutout).

    Many questions indeed, and thanks for responding ..

    1. Hello!
      I did not compare the passive radiator version (8l) to the KH120A. The BR version goes even deeper, but needs a bigger enclosure (9,5l). If size doesnt matter I would recommend to build the 9,5l version (PR or BR).
      You can buy the technical kit in my shop if you live in the EU. If not, you can buy the plan and then get the parts from any dealer in your country.
      The housing / cabinet you have to build anyways.
      I used the hypex as an external unit. You are free to put it in the cabinet. But it needs its own chamber.
      Meantime I would prefer to use a mini-dsp setup.
      DSP setups are available for Hypex and Mini-DSP systems.

      I hope I could answer your questions!
      Best regards

  2. The KH120A is perfectly in phase at crossover on-axis while the DXT-MON is not in phase on-axis.
    The KH120A has put the woofer more forward and the tweeter more back in the waveguide and combined they are giving the right amount of vertical distance to the acoustic centers of the woofer and tweeter so they are in phase, no phase correction needed in the crossover. The DXT-MON has the tweeter slightly back in the waveguide too but no forward woofer and the result is that the acoustic center of the tweeter is actually more forward than the acoustic center of the woofer, hence they are not alligned. This is not corrected for in the crossover.
    1.8kHz when listening on the DXT-MON.
    I would like to add a point to the KH120A for this ..

    1. Hello Marcel
      Thanks for your comment. I have to contradict you unfortunately.
      Althoug the voice coils of the Kh120A are closer to each other than those of DXT-MON, Kh120A's woofer is even more delayed than DXT-MONs! The woofer delays are about 0,24ms (~ 8,2cm) vs. 0,18ms (~ 6,5cm) [KH120A / DXT-MON].

      Here both steps are compared:

      Step response KH120A vs DXT-MON

      And ...
      DXT-MON is very well in phase at the crossover point.
      You can see that eg. In the vs-zero chart:

      kind regards

  3. As the owner of a pair of the KH120, I recently had a friend come to visit me with his newly built couple of DXT-Mon. We heard and measured the speakers under exactly the same acoustic conditions. There were significant differences in sound and metrology in the low bass and in the treble. The KH120 developed a lot more low frequency energy under 100Hz in our test, but the DXT-Mon was fresher and more lively (stage, localization sharpness and detachment from the speakers was very good for both couples). With the EQ of the KH120 you could attenuate the acoustic and metrical first very significant difference (KH120: + 1dB in the treble, -3dB in the lower middle, -1,5dB in the bass) but the DXT-Mon was still the clear winner in terms of sound. It should be mentioned that I use the KH120 always additionally with a DSP for room correction, but the test was first without EQ and then only with the onboard means of KH120 (the DXT-Mon was already "just right"). A clear building recommendation from me!

  4. A great and objective comparison test.

    All acoustic characteristics and the price difference aside - the DXT-MON is in my eyes far, much more beautiful to look at!

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