Kvålsvoll Design Audio Forum

EnglishEnglish text EN    NorskNorsk text NO
Please or Register to create posts and topics.

Compact Horn subwooferene


Kvålsvoll Design subwoofers are different variants of the Compact Horn, a principle developed by Kvålsvoll Design for proper bass in a relatively compact format.

Compact Horn means acoustic coupling from the cone to the air through a long acoustic channel, which is damped with one or more small damping channels. This principle enables the creation of quite small subwoofers that have both deep bass and lively upper bass.

The V-series is slightly more expensive units, with a long, narrow horn opening:

V-Series Compact Horn Subwoofers

The T-series are the original units with a port opening near the driver:

T-Serie Compact Horn Subwoofere

This article explains a bit about the principle, how they differ from other subwoofers, and what is achievable:

Compact Horn Subwoofer Technology

The sound is different from regular subwoofers. The sound character closely resembles large, traditional bass reflex cabinets with large drivers, featuring impact and punch in the mid and upper bass. The difference is that Compact Horn subwoofers also deliver rich deep bass, truly deep bass.


(NO text)

Kvålsvoll Design subwooferene er forskjellige varianter av Compact Horn, et prinsipp utviklet av Kvålsvoll Design for skikkelig bass i relativt lite format.

Compact Horn betyr akustisk kobling fra membranen til luften, via en lang akustisk kanal, som er dempet med en eller flere små dempekanaler. Dette prinsippet gjør det mulig å lage ganske små subwoofere som har både dypbass og livlig øvre bass.

V-serien er litt dyrere enheter, med en lang, smal hornåpning:

V-Serie Compact Horn Subwoofere

T-serien er de originale enhetene med portåpning nær driveren:

T-Serie Compact Horn Subwoofere

Denne artikkelen viser litt om prinsippet, hvordan de skiller seg fra andre subwoofere, og hva som går an å få til:

Compact Horn Subwoofer Technology

Lyden skiller seg fra vanlige subwoofere. Lydkarakteren minner mye om store, tradisjonelle bassreflekskabinetter med store drivere. Med smekk og punch og driv i mid og øvre bass. Forskjellen er at Compact Horn subwooferene også spiller saftig dypbass, skikkelig dypbass.

Why and how are these special?

The links above have descriptions and further articles to explain. Here, I'll try to simplify this story so you don't need to read through all of that.


The purpose of a subwoofer is to produce bass. If different solutions achieve the same result, and one is much simpler and cheaper, then the complex and expensive one is meaningless. Compact Horn is complex and costly, so it must offer something in terms of better performance that is relevant to reproducing bass, for it to make sense.

For a subwoofer, capacity and how low in frequency it can reproduce are the most important factors. Then there's the issue of sound quality - we want clean, dynamic bass with power and life; we don't want 'slow' bass. Sound quality is directly linked to capacity, which might not be immediately obvious until you consider the kind of sound pressure that's needed compared to what a typical small subwoofer can deliver.

A subwoofer that seems 'slow' or sluggish might simply be set up and calibrated incorrectly. Compact Horn subwoofers are easier to calibrate correctly because they have minimal time delay. Therefore, they don't feel 'slow.'

Especially the larger models possess this power and airiness in their bass. The bass is experienced as more powerful without the sound appearing louder. This is related to how the subwoofer couples sound to the room and having sufficient dynamic capacity.

Non-linearities in a subwoofer can also make it 'slow' and lack power. Compact Horn loading changes how nonlinearities in the driver motor affect sound, so it don't manifest in the same way as in a traditional closed box. In practice, this means they perform much better when pushed to their limits.

In short, a Compact Horn subwoofer will have greater usable capacity relative to the maximum sound pressure capacity of the subwoofer. Other principles can achieve much of the same, at least in terms of capacity, as long as the installed capacity is large enough. But it requires more capacity on paper, and the enclosures become larger.

So, if you already have subwoofers with much more capacity than needed, then whether a new Compact Horn bass system is an improvement, it depends. If calibration is made the same, there may not be much to gain.


(NO text)

Hvorfor og hvordan er disse spesielle.

Linkene over har beskrivelser og linker videre til artikler som prøver å forklare. Her skal jeg prøve å gjøre denne fortellingen enklere, slik at en ikke trenger lese gjennom alt dette.


Formålet med en subwoofer er å lage bass. Hvis forskjellige løsninger gir samme resultat, og ene er mye enklere og billigere, så er den vanskelige og dyre meningsløs. Compact Horn er vanskelig og dyr, så da må det gi noe i form av bedre ytelse som er relevant i forhold til det å reprodusere bass, hvis dette skal ha noe for seg.

For en subwoofer er det kapasitet og hvor langt ned i frekvens den kan gjengi som er det viktigste. Så er det dette med lydkvalitet - vi vil ha ren bass, dynamisk bass med kraft og liv, vi vil ikke ha "treg" bass. Lydkvaliteten henger direkte sammen med kapasitet, det er ikke umiddelbart innlysende, før en ser litt på hva slags lydtrykk som trengs i forhold til det en vanlig, liten subwoofer kan levere.

En subwoofer som oppfattes som "treg" eller sløv, kan rett og slett være satt opp og kalibrert feil. Compact Horn subwooferene er enklere å få til å kalibrere rett, fordi de har liten tidsforsinkelse. Derfor blir de ikke "trege".

Spesielt de større modellene har denne kraften og luftigheten i bassen. Bassen oppleves mer kraftfull, uten at lyden høres ut som høyere. Dette henger sammen med hvordan subwooferen kobler lyden til rommet. og at det er tilstrekkelig dynamisk kapasitet.

Ulineariteter i en subwoofer kan også gjøre den "treg" og kraftløs. Compact Horn er av natur slik at ulineariteter ikke arter seg på samme vis som for en tradisjonell lukket box. I praksis så betyr det at de vil virke mye bedre når de presses opp mot grensen for hva de kan levere.

Kort forklart, så vil en Compact Horn subwoofer ha større utnyttbar kapasitet, i forhold til max lydtrykkskapasitet på subwooferen. Andre prinsipper kan gjøre mye av det samme, i hvertfall kapasitetsmessig, så lenge installert kapasitet er stor nok. Men det krever mer kapasitet på papiret, og kassene blir større.

Så hvis en allerede har subwoofere som har mye mer kapasitet enn det som trengs, vil det da oppleves som en forbedring med et nytt Compact Horn bassystem. Det kommer an på - hvis kalibreringen er lik, er det ikke sikkert det er noen å hente.

Why are they designed this way - complex, expensive, and challenging to design?

To avoid dynamic compression of transients in the upper bass range, it is beneficial to have a lightweight diaphragm and a powerful motor. Additionally, having a small excursion is advantageous to limit distortion, especially when reproducing complex signals where low and high frequencies occur simultaneously, such as in music.

This is knowledge that experienced audiophiles have known for a long time. To achieve good bass with agility and punch, you need a driver with a powerful motor, short excursion, and not too much moving mass. Membrane area provides capacity.

The downside of such an approach is that it leads to extremely large cabinets or no deep bass at all. Hence, most commercial subwoofers are based on relatively small drivers with long excursion and heavy diaphragms, mounted in small sealed enclosures. The result is 'subwoofer bass' - a round, sluggish, and slow character that colors all instruments in the bass range. Not all are entirely hopeless; some are better than others, and more expensive models often have better drivers that perform fairly well, even with long excursions.

Acoustic loading of the diaphragm can be done in a way that transfers force from the diaphragm to the movement of air, creating a much more efficient coupling to the air. This allows for the use of a small driver with a short excursion and a powerful motor, and the diaphragm doesn't need to be heavy. That's what happens inside a Compact Horn subwoofer - the long channel connects a powerful and small movement in the diaphragm to a large movement in the air.

Compared to a regular bass reflex, this horn channel works over a wider frequency range, and the area of the opening is much larger. This means that the acoustic coupling is effective over a broader frequency range in the bass, and there is much less compression because the area is larger.

The small damping channels inside the horn are there to eliminate resonances that occur in such a small horn. The channel is actually too narrow to function as a horn, it can't even strictly be called a horn, and this leads to resonances that, at best, limit the usable frequency range. The damping channels completely eliminate this problem.

The drivers in Compact Horn subwoofers have powerful motors and a voice coil system that can handle very high power, and they have a fairly long excursion. The maximum excursion is actually very large - ±30mm - for the driver in, for example, the V110 model. Along with the acoustic coupling from the horn channel, this provides a subwoofer with high capacity across the entire frequency range, even down into the ultra-low deep bass.


(NO text)

Hvorfor er de laget slik - komplisert og dyrt, vanskelig å designe.

For å unngå dynamisk kompresjon av transienter oppover i øvre bassområde, er det gunstig med en lett membran og kraftig motor. Så er det gunstig med liten slaglengde, for å begrense forvrengning, spesielt når en skal gjengi sammensatte signaler, der lave frekvenser og høyere frekvenser opptrer samtidig - slik som i musikk.

Dette er kunnskap som erfarne hififolk har visst lenge. Skal en ha god bass med snert og smekk, må det velges driver med kraftig motor, kort slaglengde og ikke for stor bevegelig masse. Kapasitet får en med membranareal.

Ulempen med en slik tilnærming er at det blir ekstremt store kabinetter, eller null dypbass. Derfor er de fleste kommersielle subwoofere basert på forholdsvis små drivere med lang slaglengde og tung membran, montert i et lite lukket kabinett. Resultatet er "subwooferbass" - en rund, sløv, treg karakter som farger alt av instrumenter i bassområdet. Ikke alle er helt håpløse, noen er bedre enn andre, og de dyrere modellene har ofte bedre drivere som fungerer ganske bra, selv med lang slaglengde.

Akustisk belastning av membranen kan gjøres slik at kraft fra membranen overføres til bevegelse i luften, slik at det oppnås en mye mer effektiv kobling til luften. Da kan en bruke en liten driver med kort slaglengde og kraftig motor, og membranen trenger ikke være tung. Det er det som skjer inni en Compact Horn subwoofer - den lange kanalen kobler en kraftig og liten bevegelse i membranen til en stor bevegelse i luften.

Sammenlignet med en vanlig bassrefleks, så virker denne hornkanalen over et bredere frekvensområde, og arealet i åpningen er mye større. Det betyr at den akustiske koblingen er effektiv over et større frekvensområde i bassen, og det blir mye mindre kompresjon fordi arealet er større.

De små dempekanalene inne i hornet er der for å fjerne resonanser som oppstår i et slik lite horn. Kanalen er egentlig for smal til å fungere som et horn, kan vel strengt tatt ikke engang kalles for horn, og da oppstår det resonanser som i beste fall begrenser det nyttbare frekvensområdet. Dempekanalene eliminerer dette problemet helt.

Driverene i Compact Horn subwooferene har kraftig motor og svingspolesystem som tåler veldig høy effekt, og de har ganske lang slaglengde. Maksimalt utsving er faktisk veldig stort - +-30mm - for driveren i fx V110. Sammen med den akustiske koblingen fra hornkanalen, gir dette en subwoofer med høy kapasitet over hele frekvensområdet, også nedover i dypbassen.

Comparing Subwoofers:

The size of the driver is commonly used as a rough measure of how large or powerful a subwoofer is. For example, a subwoofer with a 12" driver is considered more powerful than one with a 10" driver. This way, you can decide that you want subwoofers with 12" drivers and narrow down your options - anything with a 10" or 15" or a different size than 12" is ruled out.

However, this method has its limitations; it's very simplistic. A 10" driver with a long excursion and a good motor can outperform a 12" driver with a less advanced construction.

For Compact Horn subwoofers, this method is useless. The acoustic amplification significantly increases capacity compared to another regular subwoofer with the same size driver.

For instance, a T6-Flat has a small 6" driver. The port significantly contributes here, even up to around 100Hz, where it roughly doubles the effective power input. Below 30Hz, the port's contribution is so substantial that it's equivalent to a 4-times increase in the diaphragm's surface area.

Therefore, you need to consider capacity in terms of dB to evaluate performance relative to another subwoofer. Additionally, the factors mentioned earlier play a role in making them perform better near their limits.


(NO text)

Sammenligne subwoofere:

Størrelsen på driveren er vanlig å bruke som et slags omtrentlig mål for hvor stor, eller kraftig, subwooferen er. Slik at en med 12" element er kraftigere enn en med 10". En kan da bestemme seg for at en vil ha subwoofere med 12", og slik få begrenset utvalget - alle med 10" eller 15"  eller noe annet enn 12", utgår.

Metoden har svakheter, det blir veldig unyansert. En 10" driver med lang slaglengde og god motor kan være overlegen en 12" med rimeligere konstruksjon.

For Compact Horn subwooferene er denne metoden helt ubrukelig. Den akustiske forsterkningen gjør at kapasiteten blir mye større enn for en annen vanlig subwoofer med samme størrelse element.

En T6-Flat har en liten 6" driver. Porten bidrar her betydelig helt opp til rundt 100Hz, der det tilsvarer omtrent dobbel effekt inn, og ned mot 30Hz er bidraget fra porten så stort at det tilsvarer en 4-dobling av arealet.

Derfor må en se på kapsitet i dB, for å kunne si noe om hvordan ytelsen er i forhold til en annen subwoofer. Så kommer i tillegg de faktorene som er nevnt over her, de virker bedre opp mot grensen.

(Post edited)

Some of the subwoofer designs have been available for purchase, in limited numbers.

Kvålsvoll Design is a tech development company, focusing on development of technology and product design.

Article on Horn Bass (Norwegian Language):


This article from 2017 is about horn bass in a more general sense. It attempts to describe simply how it works and what it means for the sound.

What are the sound differences going from smaller to larger Compact Horns:

Comparing a T6018 to a larger model of the same type, such as T138 or V110, it may not seem like there's a significant difference on paper, just a few dB more output for the larger models and a slightly lower lower-frequency limit. Is there a noticeable difference in sound, and how is it perceived?

A T6018 is about the smallest possible design with a 12" driver, and it approaches the behavior of a regular ported box (bass reflex) in many ways. The larger models have more horn loading, which performs better over a larger part of the frequency range - there's more horn.

This is noticed by the fact that the larger models are experienced as more powerful in the bass, with more impact and punch. How this difference plays out in practice also depends on the room and placement. The difference is noticeable at low volumes and becomes more pronounced as you increase the volume.


(NO text)

Hva er forskjellen lydmessig, fra mindre til større Compact Horn:

En T6018 i forhold til samme type, bare større, fx T138, eller V110. På papiret ser det ikke ut som det er så stor forskjell, bare noe få dB mer output for de større modellene, og litt lavere nedre grensefrekvens. Er det merkbart lydmessig, og hvordan merkes det.

En T6018 er omtrent det minste som går an å lage med en slik 12" driver, den nærmer seg en vanlig portet box (bassreflex) i måten den oppfører seg. De større modellene har mer hornlading, som virker bedre over en større del av frekvensområdet, det blir mer horn.

Dette merkes ved at de større modellene oppleves som mer kraftfull i bassen, mer slagkraft og punch. Hvordan denne forskjellen utarter seg i praksis, kommer an på rom og plassering også. Forskjellen er merkbar på lavt volum, og blir større når en drar opp volumet.

Capacity of Compact Horn vs. Closed Box:

I currently have a simulation set up where I can compare a T6-A with the same-sized driver, a 6", in a closed box.

I adjusted driver parameters slightly for the closed version, reducing BL and nearly doubling the moving mass. The total cabinet volume is approximately the same as a T6.

In this scenario, it turns out that the Compact Horn T6 has half the diaphragm excursion and twice as much output (+6dB) compared to the closed box at 40Hz. To achieve the same performance from a closed box, diaphragm area must be increased by a factor of 4, so a 6" in the T6 is equivalent to a 12" in a closed box.

The difference is even greater down towards 30Hz and diminishes as the frequency increases. At 60Hz, the T6 provides approximately double the performance, meaning it's equivalent to doubling the diaphragm area.

The efficiency is better for the T6, thanks to a combination of acoustic amplification and more favorable driver parameters.

The difference is most pronounced at lower frequencies, which is advantageous since lower frequencies are where capacity reaches the limit first. However, horn loading also offers advantages as the frequency increases, becuase BL is higher, and the moving mass is lower.


(NO text)

Kapasitet Compact Horn i forhold til lukket box:

Jeg har en simulering satt opp nå, der jeg kan sammenligne en T6-A med samme størrelse driver, en 6", i lukket kabinett.

Jeg justerte driverparametere litt for den lukkede versjonen, redusert BL og nesten dobbelt så stor bevegelig masse. Kabinettvolum totalt er omtrent lik en T6.

Da viser det seg at Compact Horn T6 har halvert utsving på membranen, og dobbelt så stort (+6dB) output i forhold til lukket kabinet, ved 40Hz. For å få samme ytelse fra et lukket kabinett, må membranareal økes med 4 ganger, slik at en 6" i T6 tilsvarer en 12" i lukket kabinett.

Forskjellen er enda litt større nedover mot 30Hz, og minker oppover i frekvens. Ved 60Hz gir T6 omtrent dobbel ytelse, dvs. tilsvarer dobling av membranareal.

Effektviteten er bedre for T6, dette skyldes en kombinasjon av akustisk forsterkning og mer gunstige driverparametere.

Forskjellen er størst ved lavere frekvenser, og dette er gunstig fordi det er lave frekvenser som først begrenser kapasiteten. Men hornladingen gir fordeler også oppover  i frekvens, fordi BL er høyere og bevegelig masse er mindre.

Examples of Installations:

Several pictures of installations with Compact Horn bass systems have been shown on the pages here, including several in Room 2 at my location and other rooms at customers' locations, like Bjarte's system with T6018+T6.

One customer has acquired 4x V110, which are now part of a unique full-size horn setup. This could be interesting to showcase and provide some details about. In this case, the bass system with 4x V110 is relatively small in physical size compared to the main speakers, which have large midbass horns and large midrange horns.

In another setup, the owner found two T6018s, which became the bass section in a full-size horn setup with large midbass horns and a large midrange horn. T6018 appears very small alongside the large horns.

Both of these horn systems are large and composed very differently. These solutions far surpass anything commercially available that can be bought in a regular store. I have some pictures of both; maybe I can show some of this and provide a brief description of what they are.

(Post edited)

See the https://www.kvalsvoll.com/blog/forum/forum/my-sound-min-lyd/ section for examples of sound system installations, including Compact Horn bass-systems.

Questions have emerged, about delay and the sound coming out of the horn channel, as it has a longer distance to travel, so this sound is "slower" compared to the sound coming from the diaphragm in front?

The answer is that it doesn't become "slower"; there is no delayed sound because it sums up like a system where all contributions occur within a single cycle in the usable frequency range.

In a Compact Horn, the delay in the horn channel is also frequency-dependent, which means that there's a greater delay at the lower end of the frequency range. This significantly increases the usable bandwidth.

In a rear-loaded horn, there's an issue with the delay in the channel becoming substantial relative to the wavelength as the frequency increases. This needs to be addressed by either limiting the frequency range or removing the output from the channel at higher frequencies.

This is simulated based on a mathematical model of the system, a model that comprises electrical, mechanical, and acoustic subsystems.

A V110, in terms of frequency response, looks like this in such a simulation:

Delay can be visualized by looking at group delay (the fluctuations in the 15-20Hz range are due to numerical errors; please ignore them):

Here we see GD is lesst than 0.5 period in the whole range above 20Hz up to over 200Hz.

This is an acoustic measurements of a V110:

We see the simualtion correlates very well with the real-world V110.

Inside a room this can be the outcome, here in Room2:

We can see that the fluctuations are now larger than the GD from V110, which means the room dominates. This is a very good system where it ended up with a fairly flat and consistent GD. Typically, it often measures considerably worse.

The increase in GD right at the very bottom, below 20Hz, is due to the roll-off. This can be determined with EQ/calibration and adjusted to be better than a V110 without corrections. However, the wavelength, and thus the time for one period, is very long at such low frequencies, so a GD that appears long has no practical significance for the sound.