Matthias DXT-MON

Fully active, with the DDRC-24 of Mini-DSP and Ice-Power amplifiers

Some time ago infected with the DIY-LS virus, I was interested in the history of the DXT-Mon pursued - ultimately designed in "competition" to a widely used reference monitor of the same size. The highest quality LS I ever had were compact Focal with Beryllium HT, as a current reference serve me mainly Stax and Audeze headphones with appropriate DIY amplifiers.
After I had been looking for higher quality new speakers for my little "music room" for a while, the finished product fit into my prey scheme.
When it finally became clear that Alexander also released the DSP data for common systems for his projects, there was no stopping him, because I wanted to build actively right from the start. The 9,5l version was built.

Since I lacked a counterbalance to the rather unusual front in the standard form, I sat for a long time and figured out the shape of the case. Soon a nice piece of solid wood was found for the front,

I built the rest entirely according to Alexander's MDF plan. The "leaning" parts were made by a friend of mine on the CNC milling machine, which made things very easy.

DXT-MON active Mini-DSP CNC

The solid wood part I have repeatedly sealed with hard wax oil, the
The rest of the body I have in turn by a friend with "liquid rubber" paint.

There was some confusion when taking over the DSP data*, as it seems
did not fit - after a few (by the way, always! very fast! answered emails) the error was found and I had the appropriate turnout data (As active hardware serve a DDRC24 and a DIY power amplifier with IcePower modules).

*Note: Biquads were first used for the Mini-DSP-HD, which works internally with 96kHz. The DDRC-24, however, works with a clock of 48kHz => The biquads did not fit. The error could then be corrected very easily.

The result inspires me every time again!

I can listen to music for hours without being fatigued, the spatial image is very accurate and dissolves completely from the speakers.
With some bass boost through the room itself, the LS reach about 45Hz linearly. Equalized by Dirac Live in the bass I miss here no subwoofer, even higher levels stuck the "little ones" easily.
All in all, a speaker that leaves nothing to be desired for me and has far exceeded the set expectations.

Florian's WaveWall home theater

Looking for my perfect home theater speaker


The home theater should be more beautiful and also: sound better. In addition, I felt like a speaker self-made. Since I lack the necessary know-how for my own development, a kit came close. I was looking for loudspeakers that are flat, because they should be operated behind a transparent screen without unnecessarily reducing the space. Also suitable for on-wall if possible. Also for the side and rear speakers, I find flat on-wall speakers optimal, as well as the side seats can still be balanced halfway balanced. If the loudspeakers protrude far into the room, the distance difference to listeners outside the reference space is relatively larger ("the left ear sticks to the left rear LS, while 2m is still on the right side ...").

When radiating, I prefer a good-natured, broad radiation without discoloration. Here too, I am concerned with the beloved ones in the cheap places, since I have to admit that I usually claim the reference place myself.

In terms of level I was certified by friends that I like to hear loud or the first question in a demo is always direction of the neighborhood relations. I myself would say that I like to hear loud, but not extremely loud, so quite similar in terms of level as in a commercial cinema. Of course the speakers should be able to do that. Low bass is not so important to me in terms of music and language. For home cinema effects like explosions, a "small" DBA from 8x 12 subwoofers takes care of that anyway.

In terms of sound characteristics, I now know that bands and AMTs usually sound too soft and horns and piezos too shrill. Say a normal dome seems to be suitable for me as a tweeter. Of course, the speakers should fit into the budget. As high quality, but also so expensive that I can afford to gradually even a full-blown Xnumx Atmos setup, so operate a total of eleven Wavewall 7.1.4 speakers.

All described requirements are met by the Wavewall 182. This was the decision for me to start with three pieces (Left, Center, Right).

The construction

As often as the end result was admired ("great shape"), I swore so much about the sloping sidewalls during the construction phase. The first box I actually built with a borrowed circular saw without rail (...!). What can I say, I had wanted it so and even that went. In the meantime, I have also done the sawing by means of a circular saw, as well as with a dip saw and clamped rail. The latter is definitely the best way. After the sawing followed the milling of the chassis recesses. With a cutting circle and router no problem. But even here, the special design takes its toll. To reach the depth of only 10cm a pocket has to be milled into the back wall. At some point I had a veritable turning worm from the whole milling shop. The glueing was also not quite trivial, as it is oblique boards in several axes to force firmly. But that was somehow in the end. During the subsequent grinding, I also tried a few techniques. To round the corners finally some material must be removed. I can recommend an eccentric grinder with coarse sandpaper for this.

A cardboard flap helped to judge the rounding. An electric planer wears off material very quickly, but requires controlled application or otherwise leaves a mogul slope, that is: rather not recommended. Spatula was not wrong then and as a finish, there was rolled-up Warnex textured paint in black.

What is still missing? Oh, the crossover. As far as I like painting by numbers. Alexander provided me with additional, calculated resistances to adjust the tweeter on the screen (compensate for high tone reduction). Now just phry everything in the tight housing, tighten and ready. First impression: With the whole MDF and the heavy, massive woofers (which make a massive and very high-quality impression), the boxes are surprisingly heavy. Of course, once hung, that's no problem anymore.


How do you sound now?

Measurements are provided by Alexander. There is a scapegoat from me now. The things can play loud and bring over nice punchy bass over. The sweetspot is nice and wide, all seats are subjectively very linear. This is definitely a strength of the speakers. The tweeters sound too dull and not too sharp - fits. The stage is more in depth than forward, or is located between the boxes. Nevertheless, it did not sound perfect at first. The sound did not break 100% of the speakers (figuratively speaking). This has changed after a break-in period, which others confirm. Now it suits and sounds a lot more airy and "liberated" than at the beginning.

Second impression: After a move, the boxes are now in the new home theater active. The new, about 30qm large room is now also equipped with many more absorbers. Eight packages of rock wool and a few square meters of Basotect are installed. In addition to the eight subwoofers of the DBA play there 7x Wavewall 182, as well as other four Sammelsurium speakers from my collection. The three Wavewall 182 front speakers no longer hang directly on the AVR Denon 4300, but on an external, cheap Thomann power amplifier, the E3-250. In terms of hi-fi enjoyment, the power amp is not outstanding, it lacks resolution and dynamics. Nevertheless, it sounds quite ok and has at least greater power reserves than the AVR. The description on Alexander's website already shows the rather low efficiency by uA the closed design, ie a strong amp is recommended for the wavewalls. Nevertheless, I was surprised by the change in sound by the PA power amp. With the additional power, the Wavewalls now play much better again. Above all, the gross dynamics increased sharply, it sounds as if now significantly larger speakers at work.

In addition an anecdote: In a small cinema screening, I played a stereo title (Daft Punk) before and was convinced L and R, as well as the subwoofer. This was a mistake, it only played two Wavewall 182, no sub! The bass boost through the wall installation, as well as a strong amp can bring the Wavewalls out in terms of bass really big. And that even with slightly screwed loudspeakers, FL and FR are bent on the listening position, but this is not absolutely necessary due to the good-natured radiation behavior. So: Played Wavewall 182 powered by a strong amp sounds awesome! As a sound-describing attribute, the word "strong" comes to mind in my heavily insulated home theater.

Status: Worth the whole thing? Hard to answer. It certainly does not hurt to have the homemade really feel like it, otherwise it just is not fun. If you just want to save, you better comb the second-hand market. Conversely, it is of course a great feeling to put self-built speakers into operation! From the resale value, it is always difficult with DIY speakers, as there is no big brand behind it. Looking at material costs vs. Market prices of new speakers, it looks very different. My subjective impression is that you have to lie down significantly above 500 €, maybe even around the 1000 €, for a new home theater speaker with the same performance.


Displacement can not be replaced by anything, except by a stronger power amplifier. That's not true of course, we all know the end of the story, displacement can only be replaced by EVEN MORE HUB! In this sense, I decided to round off the home theater with larger Wavewalls, so demand from Alexander the large version with two woofers. Fortunately, he let himself be moved, half of the development was probably already in his drawer. The development of 182.2 is now complete and it looks like I'm the first customer for it. Since the speakers will be concealed anyway I build this time the simple variant, so rectangular boxes, without pockets in the back wall. So it's planned: 3x the new, large "Wavewall 182.2" with two woofers as front and center. Rear and surround back, as well as 4x Height are populated with the normal Wavewall 182. That should be enough for now ...


Here is a short summary of my experiences in the construction of the DXT-MON. For me as a "newbie" that was a great experience. Also to the effect that as a "city man" without existing workshop and appropriate tools can come to an absolutely convincing result.

I do not think our bar was set low. In the past, an 2.5 walkway speaker from an Italian manufacturer was used. Cost: 3.600 €. In our living room we hear about 25m² with 3m ceiling height.

One day I came - apparently in the wake of mental derangement, what has ridden me there? - on the idea of ​​developing a driver. That was a mistake that triggered a thought process. Behind the admittedly "chic" looking leather / MDF - front I found inside but rather disillusionment: no insulation, the switch was unenthusiastic "clicked" and the inner cut on the TMT s was actually not really available.

That left a more "emotionless" impression on me. At the same time I made the decision to actively deal with "Plan B": I listen to other speakers ...

In addition, I came to the realization that we can not optimally provide the existing floor standing speakers - this is simply not the existing space ago. Since the speaker can not help it, but should be discussed / questioned during the consultation at the local dealer more.

I did not get any further after many studio visits. The most pleasing, passive solution over a closed compact was already well above the purchase price of the then floorstanding loudspeakers. The other alternative: fully active solution. Had but my tube amplifier as a victim result, since no pre-out is available. I did not bring that over my heart. The fully active variant would not have been so cheap and my better half immediately raised the objection that the full-time people look "modest".

Somehow, the reference to DIY is missing, right? Right. I have not had that to date

Time considered. Theoretically I was informed and knew that there are solutions for the self-construction of loudspeakers. Also how these are technically implemented. And honestly, the "rocket-science" in the speaker construction also interested me somehow.

What then speaks against self-construction? Well, nothing at all. Except maybe:

No viable workshop, too little fitting tool, too much inappropriate tool, soldering crossover - I'm laughing flabbily / change light bulb is still smooth and by hand and the reminding woodwork from the elementary school was also rather "goes through" , Oh, and I do not have time either.

Actually, all traffic lights immediately jump to "red". Consistently, you keep your hands off and finish the project. But not so with people who have their home in the haze of Stuttgart 21 ... Since you are used to other, there is gas!

So, make a decision - it's built by yourself. I spent almost a year looking for a suitable concept. In addition, considerations were made as to how I can do the pending work as far as possible by professionals.

Basically, I was amazed how many building proposals are available on the net. Many of them are well documented. Unfortunately, one rarely finds the possibility that one can enjoy listening to a kit.

At some point I played Russian Roulette and made up my mind to take up the concept most suitable for my impression. In my opinion, this was the DXT-MON of Alexander Heißmann among the last 5 candidates.

I bought the tree cap and asked Mr. Hotman for a partner who made me the case. And indeed tutti kompli. I was then made aware of the joinery Thomaier, which turned out in retrospect as the right place.

Then it actually started already. The housings were commissioned and I ordered all the missing pieces of the puzzle bit by bit.

Except for the insulation, I strictly adhered to the plan of Hr. Heißmann. Only the story with the bitumen was suspect to me. The toenails opened up as I imagined liquefying the bitumen with a hot air gun. The alternative was then found: Alubutyl in self-adhesive execution.

The doubling with 2 layers alubutyl and additionally 4mm plywood was very easy and feasible without problems via the assembly hatch. Which was also very helpful: you could understand the result very well by the well-known in the net "knocking test". It was unbelievable how well the doubling worked.

Then the walk to a professional painter followed. Happy coincidence here: the painter also likes to hear stereo and was immediately hooked by the project. He then invested a whopping eight hours of work and presented me within a week an absolute top result. The drivers I have deposited with the painter, so that he could always check the passability.

And then it was time: "all in" as in poker! Final result:

How does it sound? Well. Damn good. I do not miss anything - rather the opposite! 100 points - everything done right. The loudspeakers can be very well integrated into the living space given their size.

Distance to the back wall with us: about 60cm. Passive membrane (without additional weight) directed inwards. At the lineup I will change something.

I do not write more now. All impressions are based on our circumstances, because you can simply transfer bad ...


Fits like a fist on our eyes, the speakers are really fun. Many Thanks!

Desirable (from my point of view):

@ SEAS: Sells the tweeter + 10,00 € and installed on the waveguide instead of plastic, please a more valuable material.

What would I do differently:

Definitely choose MPX for the housings. MDF comes to me personally something "strange".

Given the cost of painting (in relation to the housings), I would aim for a different solution in the future.

Cinetor-Evo Scan-Speak Discovery D2604/833000 (WG) and 18W/4434G00


  • Impedance: 4 Ohm
  • Sensitivity (2,83V/1m): 87,5 dB
  • HxWxD: 380 x 200 x 280 mm
  • Crossover frequency: 1750 Hz (LR4)
  • Frequency range (-8 / -3dB): 42 / 55 -> 20000 Hz
  • Concept: Bass reflex 14l


  • Main / Center / Rear in home theater applications
  • Monitoring / Midfield
  • ambitious stereo installations
  • Bar & Pub
  • Extension to Disco-M as "Disco-S"


  • exceptionally uniform directivity
  • neutral sound reproduction
  • Very convincing bass performance. When playing music usually no subwoofer is required.
  • impressive power handling, especially in applications with subwoofer support
  • extremely low harmonic distortions, even at very high levels.


Scan-Speak Discovery D2604/833000 with waveguide PCT-300/WG-300

Scan-Speak Discovery 18W/4434G00



WaveWall-182 | In-Wall | In-wall speaker with WF182BD10 and TW030WA09



  • Nominal impedance: 4 Ω
  • Crossover frequency: 1850Hz
  • Sensitivity (2,83V/1m): 84 dB
  • Concept: 2 ways, closed-box
  • Dimensions (HxWxD): 321 x 450 x 140mm (=> flexible, due to in-wall-mounting)
  • Net volume TMT: 11l
  • Frequency range (-8 / 3dB): 32 / 47 - 30000 Hz


  • In the living room with maximum WAF
  • Center / Main / Rear in home theater


  • superbly uniform directivity
  • very neutral sound reproduction
  • precise and dynamic bass, in stereo applications fullrange usable, without any compromises
  • lowest harmonic distortion even at high levels
  • thanks to half-space radiation exceptional power handling


  • Wavecor WF182BD10
Hobby Hifi 03 / 2014

These drivers (Note: WF182BD09 and WF182BD10) offer outstanding value for money. For audiophile and living room-friendly two-way floor boxes, they are simply perfect.

  • Wavecor TW030WA09
Heißmann-Acoustics: Test
Hobby-Hifi 06 / 2013

Wavecor manages with the TW030WA09 to exceed the already excellent 30-millimeter tweeters of the house. The moderate price of the tweeter is not meant to deceive that it is an excellent tweeter with high-end demand and terrific value for money.


WaveWall 182.2 | In-Wall | In-wall speakers with 2xWF182BD10 and TW030WA09



  • Nominal impedance: 4 Ω
  • Crossover frequency: 1900Hz LR4
  • Sensitivity (2,83V/1m): 90 dB
  • Concept: 2 ways, closed-box
  • Dimensions (HxWxD): 642 x 450 x 140mm (=> variable, because of in-wall installation)
  • Net Volume TMTs: 2x11l
  • Frequency range (-8 / 3dB): 33 / 48 - 30000 Hz


  • In the living room with maximum WAF
  • Center / Main / Rear in home theater
  • Monitoring scenarios / Midfield


  • superb uniform directivity characteristics
  • very neutral sound reproduction
  • precise and dynamic bass, in stereo applications fullrange usable, without any compromises
  • lowest distortion even at very high levels
  • highest quality components


  • 2x Wavecor WF182BD10
Hobby Hifi 03 / 2014

These drivers (Note: WF182BD09 and WF182BD10) offer outstanding value for money. For audiophile and living room-friendly two-way floor boxes, they are simply perfect.

  • Wavecor TW030WA09
Heißmann-Acoustics: Test
Hobby-Hifi 06 / 2013

Wavecor manages with the TW030WA09 to exceed the already excellent 30-millimeter tweeters of the house. The moderate price of the tweeter is not meant to deceive that it is an excellent tweeter with high-end demand and terrific value for money.


Your construction report on

I would like to invite you to share your insights and experiences on the way to your "Heissmann Acoustics" speaker with the readers of this site.
Write your report with any word processing program, add a few photos and send it to me via email to baubericht[at] You will soon be able to read the article under "Construction Reports". I am looking forward to it!

DXT-MON-RLY Compact monitor speaker with Seas DXT 27TBCD / GB and...



  • Nominal impedance: 4 Ω
  • Crossover frequency: 1900Hz LR4
  • Sensitivity (2,83V/1m): 83 dB
  • Concept: 2 ways, bass reflex
  • Dimensions (HxWxD): 324 x 200 x 254mm
  • Net volume: 9,5l
  • Frequency range (-3dB): 56 - 40000 Hz


  • Near field monitoring
  • High-end desktop speakers
  • High-quality stereo aplications in small to medium sized rooms
  • Home theater: Main / Center / Rear with subwoofer support


  • extremely uniform directivity
  • superb impulse response and resolution
  • precise bass response
  • very low distortions


Seas Prestige ER15RLY (H1455)

Seas DXT 27TBCD / GB (H1499): Test


Disco-M Scan-Speak Discovery D2604/833000 (WG) and 22W/4534G00



  • Impedance: 4 Ohm
  • Sensitivity (2,83V/1m): 86 dB
  • HxWxD: 440 x 250 x 300 mm
  • Crossover frequency: 1790 Hz (LR4)
  • Frequency range (-3 dB): 46 -> 20000 Hz
  • Closed-Box with high-pass capacitor (GHP), 20l

Applications & Properties

  • Studio monitoring
  • Highest quality stereo applications
  • High-End home cinema (subwoofer recommended)
  • Very uncritical in terms of placement (also near-wall is possible)
  • Room size: >= 15m², also suitable for very large rooms


Scan-Speak Discovery D2604/833000 with waveguide PCT-300/WG-300

Scan-Speak Discovery 22W/4534G00 ⇒Surely one of the best 8 midrange speakers in the market



Cost example ( Stand 06 / 2018)



From Thorsten Felbingers pen (⇒ originated the concept, which, so to speak, "A perfect match"To my investigations in matters Baffle geometry, sloping chamfers & my measurements different Tweeter at Waveguide fits. It lacked only the means and opportunities to develop the passive crossover ... That's how easy win-win situations arise :).

See also the report at

Test Scan-Speak Discovery H2606 / 920000 26mm dome tweeter 4 Ω with waveguide

Datasheet ©
Measurements in DIN baffle in 50cm distance at 2,83V. Level scaled to 1m.


Frequency response 2,83V / m & impedance


Even frequency response with smooth XCHARXRoll-OffXCHARX. Slight interference around 10kHz.

Due to the waveguide very high efficiency of 95,5dB / 2,83V / m.

By thin fluid ferrofluid slightly damped, very symmetrical resonce at 1,1kHz



The 4 measured copies run, in the working area, nearly congruent, both in the amplitude, - and impedance response with a maximum deviation of + -0,35dB.

Directivity horizontal (0°, 15°, 30°, 45°, 60°)


Wide dispersion up to ~ 2,5kHz, then rapidly and evenly getting narrower towards the super highs.

Burst decay


Overall, very even and rapid burst-decay, minimally delayed in the super high.

harmonic distortion (90, 95 & 100dB / m)


Very low harmonic distortion, at all measured levels> 1,5kHz

K3 barely exceeds, even at 100 dB / m, the 0,1% mark . K2 remains inaudible.


Frequency response / directional behavior:
Power handling:


The Scan-Speak Discovery H2606 / 920000 is a fine tweeter, which, when used wisely, leaves practically nothing to be desired. Without hesitation, it can be used from 1,5kHz, even with high level requirements. Depending on the application possibly even deeper.

Due the somewhat special dispersion this tweeter asks for a mindfull connection to te midwoofer.

The H2606 is used in the kit Suzy-Q

Suzie „Q“ with Scan-Speak Discovery H2606 / 920000 and 22W / 4534G00



  • Impedance: 4 Ohm
  • Sensitivity (2,83V/1m): 87,5 dB
  • HxWxD: 453 x 280 x 265 mm
  • Crossover frequency: 1800 Hz (LR4)
  • Frequency range (-3 dB): 45 - 19000 Hz
  • Closed-Box with high-pass capacitor (GHP), 22l


  • near wall or freely placed
  • Room size:
    • From 15m² ...
    • moderate volume requirements also suitable for very large rooms
  • Hometheater (Subwoofer recommended)


The purpose:

  • "Metrological balance", "pleasing design" and "easy to build" get under one roof, without losing my knowledge of things Baffle geometry , equipped …
  • ... with high quality, bargain drivers

The concept found: An 8 "/ 1" combination of Scan-Speak Discovery drivers, in a tendentially wide baffle.

The speaker was given a slight "sounding" without leaving the room of acoustical neutrality. A slight note of warmth accompanied with a decent dip around 20khz. A realy "good" sounding speaker, nothing missing in detail. Particularly impressive, the serenity with which the 22W / 4534G00, plays if he "only" has to work down to 45Hz!

"Sounds like a good red wine tastes ... relaxed, confident and sublime" (User "tiefton" from the DIY-HIFI forum)


Scan-Speak Discovery H2606 / 920000 and 22W/4534G00



Cost example ( Stand 12 / 2017)


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 this is a bit broadband, but the longitudinal resonance of the BR channels (at 120kHz) shows up in the KH-1,5A. I would be inclined to attach a little more importance to longitudinal resonance, it would anyway draw call.

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



DXT-MON has slightly higher XNUMX distortions below XNUMXHz. Alright, for that, in the same area, (at XNUMXdB / m significantly) lower distortion XNUMX. Order. XNUMX. There is not much order between the two. DXT-MON is a little less impressed by the level change between XNUMX and XNUMXdB / m than the KH-XNUMXA. Along with the lesser, more annoying distortions of XNUMX.order, I get DXT-MON to do so, though tight but deserved to be the winner of this discipline. + XNUMX 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

Test Scan-Speak Discovery D2604 / 830000 with WG PCT-300 / WG-300 26mm dome tweeter 4 Ω 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.

Scan-Speak D2604 / 830000 WG

Directivity horizontal (0 °, 15 °, 30 °, 45 °, 60 ° & 90 °) & Impedance


... normalized to 0 ° (sonogram)


Due to the waveguide system-related symmetrical peak from 1-10kHz.
Extremely uniform directivity without significant disturbances. In the main very close to "Constant Directivity". The slight widening around 2,5kHz can be equalized by skillful choice of the midrange and its filtering.

Burst decay


Overall, very smooth and rapid decaying over all frequencies.

Minimal delayed in the super high tones.

harmonic distortions (90-105dB / m)


K3 remains in the range <105% at all measured levels, even at 1dB / m> 0,9kHz.

K2 increases evenly with increasing level and exceeds> 1kHz the 1% mark only at levels> 100dB.



Frequency response / directional behavior:
Power handling:
consisty / without rating:


The Scan-Speak D2604 / 830000 measures itself at the Waveguide, apart from the ~ 1dB lower efficiency practically identical to the D2604 / 833000, Therefore, the same conclusion:

In terms of "dome tweeter with waveguide" remain, realistically, nothing to be desired. Very broadband usable, extremely low-level distortions and in terms of directivity close to the ideal ...

Software supported crossover development ... or simulation vs. "Reality"


The aim of this article is to consider the mode of operation, the far-reaching possibilities and, ultimately, the reliability of software-supported crossover development. It will exclusively the use of the computer as virtual crossover considered. No housing simulation, no frequency deviation simulation according to data sheets, TSP or any other parameters that are not based on real measurements on the object ⇒ All relevant data is obtained from real measurements!

The concrete approach in software-based crossover development is usually the following

  • Concept creation (driver / housing / baffle geometry) taking into account all possible factors, which will not be discussed here
  • Structure of the speaker: Case construction, absorption / insulation, cabling, bass tuning (BR / CB etc.) ⇒ Without crossover
  • Measurement of the individual, unfiltered drivers: Amplitude frequency response including relative acoustic phase under all desired angles and impedance response
  • Import of measurement data into the software, in this case Xover 2.04A

At this point a note: The measurement of a 2-way speaker under eg. 22 angles (+ -90 ° horizontal in 15 ° steps and + -20 ° vertical in 5 ° steps) including impedance measurements takes ~ 15 minutes

Let's imagine the following measurement setup

  • A cascade of "n" identical measuring microphones in a horizontal and vertical plane around the speaker, which do not influence each other
  • A measuring device for detecting the impedance paths of the individual drivers and the whole loudspeaker simultaneouslywithout affecting the results
  • Hardware that can process and output all measurement results in real time
  • Software that can process and output all measurement results in real time
  • All required components without deviation from the setpoint ... Components that can be set to any value via the controller
  • A transparent translator that changes / adjusts parts on instructions 😉

Everything is not really feasible, but should illustrate what is possible if we collect all the data one after the other and then let the software work with it.

Here is an example of the course of a crossover development with Xover 2.04a

The program is on the pages of the interest group DIY Hifi (IGDH eV) as download available.

Top left: 0-90 ° Horizontal, sum / branches and phase
Top right: 0 ° and + -15 ° vertical, sum / branches and phase
Middle bottom: Impedazgänge branches and total
Bottom right: Voltage frequency response
Quiz question: What's going on at 1kHz? Use the comment function :)

We have a virtual crossover board on the screen, and see the effects of each component change on the amplitude frequency responses (horizontal and vertical), phase, impedance, and voltage response in real time. We can simultaneously Things that the on-foot developer thinks if any, only one after the other.

There is usually "on foot". on Microphone, one Impedance measuring stripe and on Component that is changed. Then you can a Zweig or the sums, or look at the impedance frequency response. Everything under one Corner. The effects of a component change can basically only one aspect to be viewed as. The effects on other aspects have to be "anticipated" ...

If I change the slope of the tweeter in favor of a better phase angle, how does this affect the radiation behavior horizontally and - or vertically?

Of course, even very good speakers can be created. Direct-HA is the last speaker I've ever designed ... The results are very good, but it took hours for things to go in minutes or seconds. Meanwhile, I find it very questionable if the last bit of detail can really be achieved in an on-foot development.

Is there still the question of accuracy ...

In order not to anticipate it quite unprovokativ: The virtual, - is more accurate than the real development ... 😉 ...

We have real measured values ​​of the drivers (amplitude frequency response including rel. Phase and impedance response) and put them in a (virtual) AC circuit with frequency-dependent (L / C) and frequency-independent (R) impedances. The mode of action of capacitors, coils and resistors can be detected by formula. There are no relevant unknowns.

In contrast to the "real" development turnout, there are virtually no sources of error. The components have no deviations, there are no increased contact resistance, no cabling errors, no component confusion, no cold solder joints.

So that Reality In the end, there are really only a few possibilities:

  • Measurement conditions have changed (measurement setup, temperature, ...)
  • Components deviate from the standard value
  • Errors in the structure (crossover, cabling, faulty components ...)

If we trust our measurements, we can look at differences between reality and simulation, the error on the real object. Often the simulation can help here as well. We carry out targeted changes as long as the results correspond to the error. So I have often found out which component differs from the norm, where a contact resistance is too large, or where two components were confused. It will not be published until the simulation and final measurements of the speaker are practically the same. The virtual crossover as a reliable fault diagnosis tool!

Here's an example of the match between simulation and measurement on the finished speaker:

In Jumping simulation and final measurements of a speaker at horizontal angles of 0-90 ° in 15 ° steps

It can be practically talked of congruence at all angles. The minimal deviations are due to slight deviations in the final measurement setup and possibly tolerances in the components.

The advantages of a software-supported crossover development summarized once again

  • time
  • Material: No cabinet with components needed.
  • More efficient crossovers: "On foot" as well as in the simulation, a "filter finding" runs like this: You start with one, let's say high-pass 2. Order and a voltage divider. Then an elevation disturbs, which is then smoothed out with a barrier, - or absorption circle. So now everything looks good you're done "on foot". In the simulation you can now try to find a filter function that delivers an identical result with fewer and / or less expensive components ... works frequently!
  • The simulation as a fault diagnosis tool. If simulation and final measurements match, it can almost certainly be assumed that they are faultless. Very good in terms of "replica security"
  • Steep learning curve in terms of filter design, certainly synonymous with experienced developers ...
  • Variability: Variations of a loudspeaker can also be created retrospectively, because a complete and verified simulation model exists.
  • "Trial & Error Soft" until it fits => predefined acoustic filter edges
  • The cascade of "n" identical measuring microphones ⇒ An extremely practical way to the "controlled directivity" loudspeaker

In conclusion:

The art of developing a good loudspeaker should not be primarily in the design of the frequency softening, but rather in finding a coherent overall concept for the intended work area. Find very good drivers and define a meaningful workspace. A good case design (inside and outside) and the often overlooked baffle geometry. How the drivers ultimately want to be filtered is, in my opinion, largely predetermined by the overall concept. Theoretically we could leave the crossover development entirely to the computer ... A good switch optimizer, fed with 360 ° measurements horizontally, vertically and diagonally, to which we make specifications regarding the energy behavior of the loudspeaker and the application area of ​​the drivers, will find better / more effective course than we can , Except of course is "the first litter of the experienced developer" 😉

Diagonal chamfers ... effect, steepness and positioning

The topic of baffle geometry, and its influence on the playback quality of loudspeakers, has already been described in the article "About baffle design, edge diffraction, secondary sound sources, ..."Detailed. If you are still in the belief that designing a baffle and the arrangement of the drivers on Selbiger is primarily a question of optics, may the article like (again) read.

In the process of finding a suitable baffle, I often ended up with the variant "slanted chamfering". Again and again, the question arose how steep these really have to be to be effective. So far I have relied on secondary knowledge in this regard ... Read in books, forums, magazines. When the question arose recently, I decided to investigate the matter metrologically.

To accomplish this, a baffle with adjustable, beveled chamfers had to be made. After a lot of headache, how to build this, I finally came to the following conclusion:

schraege_fase_variabelIt was milled from behind a V-groove, just less deep than plate thickness, the whole thing with tape from the front "secured" and a 2mm strong copper wire festgetackert from above, which serves as an adjustment mechanism. The "wings" can be set as desired by 0 ° -55 °.


As a tweeter, I chose one that by itself shows no disturbances in the straightening behavior, in the area relevant for edge diffraction, which could falsify the results. The choice a lot on the very much appreciated by me XT25TG-30 / 04.

In 55 ° steps for chamfer angles of o-5 °, the respective radiation behavior of 0-90 ° in 10 ° steps was measured. Altogether 120 measurements.

The initial situation: Bevel angle 0 °

See also "Worst case" scenario

The left picture shows the radiation behavior in a sonogram normalized to 0 °. The right-hand example shows the angles 0, 30 and 60 °.

In the sonogram it can be seen that the loudspeaker at 3kHz is far too broad, and too narrow at it. Axis, and angular frequency responses are unbalanced to each other. Where there is a sink on the axis, there is an elevation under angles. The speaker changes its character with the listening position. Desirable would be a steady and evenly narrowing course.

Measurement results

Sonogram for chamfers with a slope of 0-55 ° in 5 ° steps


0,30 and 60 ° for bevel angles of 0-50 ° in 10 ° steps


The main disturbance (widening by 3kHz along with the constriction below) decreases with larger chamfer angle. Chamfers with a steepness <20 ° do not bring satisfactory results yet.

The chamfers themselves form a new edge, which comes to bear with increasing steepness. Recognizable by the arising expansion around 5Khz. This is less pronounced because the tweeter in this area is no longer working as a half-space radiator.

This is also one of the main tasks of the oblique chamfer, in addition to the resolution of the "rectangular geometry": to bring the case edges so close to the tweeter that it no longer "sees" them or only weakens them. Less distance ⇒ Smaller wavelength higher frequency ⇒ more directivity ⇒ less influence of the edge

The concept "oblique chamfer" works particularly well when the tweeter in the corresponding frequency band already bundles clearly and thus this is practically no longer "seen". Of the Seas DXT 27TBCD / GB be mentioned here by way of example. How well this driver works with oblique chamfers is an example DXT-Mon to see.

In summary:

  • Bevel <20 ° are not sufficiently effective
  • The distance of the chamfers to the place of sound creation must be sufficiently low, otherwise one reaches only one, at least partial, displacement of the problem
  • Depending on the situation, the chamfers can also zu steep be!

The concept of slanted chamfers can not be very effective to solve the problem of secondary sound sources by edge diffraction. But not unconditionally. Slope and position must be chosen carefully and according to the concept. If you asked me for a universal recommendation I would say:

"Make the chamfer 25-35 ° steep and position it as close to the tweeter as possible"

Finally, the measurements in single images, for those who want to take a closer look. The steepness of the chamfer is in the lower left corner of the picture.

Note: The picture change is also possible with the mouse wheel

Test Scan-Speak Discovery D2604 / 833000 with WG PCT-300 / WG-300 26mm dome tweeter 4 Ω 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.


Directivity horizontal (0 °, 15 °, 30 °, 45 °, 60 ° & 90 °) & Impedance


... normalized to 0 ° (sonogram)


Due to the waveguide, system-induced symmetrical peak from 1-10kHz.
Extremely uniform directivity without significant interference. In the main very close to "Constant Directivity". The slight widening around 2,5kHz can be equalized by skillful choice of the midrange and its filtering.

Burst decay


Overall, very smooth and rapid decaying over all frequencies.

In super high tone> 15kHz minimally delayed.

harmonic distortions (90-105dB / m)


K3 remains at <105% at all measured levels, even at 1dB / m> 0,5kHz, and is largely independent of the excitation signal.

K2 rising evenly with increasing level and exceeds the 1% mark appreciably only at levels> 100dB.



Frequency response / directional behavior:
Power handling:
consisty / without rating:


The reader may like the one or the other similar to Peerless DX25TG09-04 (Vifa XD-270 F / 4) on the waveguide to have noticed ...

The Scan-Speak is practically equivalent in all respects. It measures on axis a touch more restless, can play minimal louder, could probably be crossed slightly deeper, .
In terms of "dome tweeter with waveguide" remain, realistically, nothing to be desired. Very broadband usable, extremely low-level distortions and in terms of directivity close to the ideal ...

Center HQ & Compact HQ center/rear for Samuel HQ, universal speaker



  • Impedance: 6 Ohm
  • Sensitivity (2,83V/1m): 84 dB
  • HxWxD (mm): 204 + 69x 356x321
  • Crossover frequency: 1900 Hz
  • Frequency range (-8 / -3dB): 48 / 69 -> 30000 Hz
  • Concept: closed box, 15l


  • Home Theater:
    • Center
    • Main
    • Rear
  • Monitoring
  • Audiophile stereo applications


  • flat frequency response
  • very uniform dispersion, both horizontally and vertically
  • from 200Hz very gently sloping bass close to the wall possible
  • standing and lying operable


Peerless XT25SC90-04 (Vifa XT-25 / Neo4)

Test at Heiß

Monacor SPH-175HQ

Sound and sound 06 / 2012

The SPH-175HQ passed our test course with bravura... Very high-quality driver, which cuts a good figure both in two-way constructions and as a low-frequency specialist


building plan

Test Scan-Speak Discovery D2604 / 833000 26mm dome tweeter 4 Ω

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

Scan-Speak Discovery D2604 / 833000

Frequency response and impedance (consisty)

Scan-Speak D2604 / 833000 frequency response

Extremely broadband frequency response. Full level from 1,1kHz, with good linearity.

The average efficiency is exceptionally at 93dB / 2,83V.

Impedance is flawless. The resonant frequency with 430 respectively 440Hz is below the manufacturer's specification of 475Hz.

Both drivers behave almost congruently both in amplitude and impedance.

Directivity horizontal (0°, 15°, 30°, 45°, 60°)

Scan-Speak Discovery D2604 / 833000 directivity

Directivity of the Scan-Speak D2604 / 833000 is even and balanced throughout the entire transmission range.

In the top octaves> 10kHz significantly wider radiating than, due to the effective membrane area of ​​8cm², would be expected.

Burst decay

Scan-Speak Discovery D2604 / 833000 burst decay

Overall smooth and fast decay over all frequencies.

> 10kHz minimally delayed.

harmonic distortions

Scan-Speak Discovery D2604 / 833000 distortions

The Scan-Speak D2604 / 833000 has outstanding low harmonic distortions.

K3 remains below 1% at all measured levels> 0,5kHz largely independent of the excitation signal.

K2 increases with the level, extends very evenly and would not reach the 1% to 1dB / m even with a crossover-point at 100kHz!


Frequency response / directional behavior:
Power handling:
consisty / without rating:


With an effective membrane area of ​​8cm², a resonant frequency <500Hz and the very low harmonic distortions, the driver invites to be deeply crossed eg. to a 20er Mid-Woofer. Crossover frequencies> = 1,5kHz should be possible without any problems. In smaller systems, eg with a 13er TMT, the Scan-Speak D2604 / 833000 could be crossed even at lower frequencies.

The concept of a large effective membrane area, in combination with a "standard voice coil" (26mm), and a rather soft dome material works out. Widely radiating in te top octaves, crossable very low, with high load capacity.

=> Scan-Speak D2604 / 833000 with waveguide

DXT-MON Reference 10l Monitor Speaker with Seas DXT 27TBCD/GB, Wavecor WF152BD06 + Seas SP18R


  • exceptionally pure and neutral sound
  • superbly uniform directivity
  • outstanding impulse response and resolution
  • lowest harmonic and non-linear distortions


  • Nominal impedance: 4 Ohm
  • Crossover frequency: 1800Hz LR4
  • Sensitivity (2,83V/1m): 83 dB
  • Principle: 2 ways, bass reflex / passive membrane
  • Dimensions (HxWxD):
    • Version PM 8l: 308 x 204 x 244mm
    • Version BR / PM 9,5l: 330 x 204 x 258mm
  • Net volume: 8l or 9,5l
  • Frequency range (-3dB):
    • Version PM 8l: 54 - 40000 Hz
    • Version PM 9,5l: 50 - 40000 Hz
    • Version BR 9,5l: 50 - 40000 Hz


  • Near field monitoring
  • High-end desktop speakers
  • High-quality stereo aplications in small to medium sized rooms
  • Home theater: Main / Center / Rear with subwoofer support


Wavecor WF152BD06

Klang & Ton 02 / 2013

In this as in all other respects, the new driver is perfect: even at 95 decibel the driver has almost no distortions, has almost no resonance up to almost 10 kilohertz and shows a perfectly balanced frequency response ... The processing is Waveor-typical excellent - they only have the best materials installed.

Seas DXT 27TBCD / GB (H1499): Test



16mm MDF, with bitumen, - plywood sandwich. The front has a thickness of 38mm. This is eg. achieved by gluing two 19mm plates.


Cost example ( Stand 05 / 2017)

Buy cabinet kits


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.


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.


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. It raises the question of the meaningfulness of Polkernbohrung and back chamber at the dome.


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.