Tuning the cabinet to the actual loudspeaker

First of all, the loudspeaker should be rigidly and precision fitted to the front panel. A liquid semi-permanent sealant or no sealant are both better options than a thick foam type seal, because the required tensioning of the screws, bolts or t-nuts that keep the loudspeaker in place can be a cause of framewarp in case of a flexible seal. Dynaudio LX2 is specifically designed for this type of seal, but it is not cheap. Seal or no seal, you should use gradual, progressive cross-wise tensioning of screws, bolts, t-nuts, whatever to prevent framewarp. Do not overdo the tensioning, re-tension the next day, the next week and the next month instead, it is likely to be required anyway because of the g-force from the "membrane recoil" acting on the frame, i. e. because of the vibrations. This is not a type of cabinet where a flexibly mounted loudspeaker is a good idea, the coupling of the loudspeaker chassis to the front panel must be absolutely rigid. Place the cabinet(s) in the intended location in the listening room. Listen to music. Listen carefully using a suitable, preplanned, repeatable sequence of material that you know well in advance. If the loudspeaker is "too bassy", then you should remove the unit, there is no other way into the upper part of the horn now, and add some rockwool, glasswool or similar to the first part of the horn after the throat. Use gloves, and remember that there is a caveat about rockwool in the context of some types of precision loudspeakers, because it may contain magnetic particles that can work their way into the airgap, glasswool is the recommended material. Do use gloves, and it may be well adviced to move the cabinet back to the workshop for the operation to avoid getting insulation material into your living room environment. What this does is to add resistive damping to the passage of the sound into the horn, i. e. it turns down horn "output". Please note that you can not so do without also somewhat compromising the horn, you may be better off using tone-controls if available. If the level around 200 Hz is too loud (listen for whether voice travels through the horn and to what extent, and listen for how the general sound of a drumkit is reproduced) long haired sheeps wool or a fiber equivalent, acoustilux is but one tradename of a suitable fiber, should be placed in the chamber below the loudspeaker unit, not behind it. This is a trial and error concept, the chamber is on the large side of what it probably should be with a unit with a suitable Qt for horn loading. Consequently this is most likely to be required in case of a unit with a Qt that is in the upper end of the recommended range, but other factors also matter, so there is no other simple guideline but to suggest trying what will work with the actual unit. This tweak mode aims at making that chamber appear to be larger. If the bass is "too loose", i. e organ pedal notes may be fine, but drumkit bass sounds are "sloopy" and do not appear to be really "meant" by the loudspeaker, then you should add an amount of sand equally distributed between the two lower parts of the chamber below the unit. When the amount is "just right", then a drumkit sounds just right, if you add too much, then the sound of the smaller drums will leap forward out of their proper perspective because then also the lower midrange will get passed on to the horn, and thus get amplified by it. Don't be scared of having to listen for these effects, they are very clearly identified once you start trying the various parameters, and it is very obvious and very rewarding when you get the tuning of the cabinet just right for the combination of loudspeaker unit, room and placement in room, and it probably is mostly about exactly matching the cabinet to the actual loudspeaker unit. The original danish text that this is a translation of supplied below for reference to resolve any ambiguity caused by the translation process.

Gode råd for afstemning af kabinettet

Højtaleren skal sidde urokkeligt fast og der skal være tæt til forpladen, men spænd skruerne forsigtigt og trinvis over kors for at forebygge at dens chassis trækkes skævt, vær især forsigtig såfremt der benyttes en pakning! Anbring nu kabinettet på det sted i lytterummet det skal stå. Er højtaleren for basset anbringes der rockwool, glasuld eller lignende i hornets start, brug handsker! Er niveaet omkring 200 Hz for højt anbringes der langhåret fåreuld i ladekammeret, hvor meget er afhængigt af højtaler-enhed og af placeringen af kabinettet, der kan ikke på forhånd siges noget konkret om mængden. Hensigten med dette er at få ladekammeret akustisk større. Hvis bassen er "for løs", så kan det hjælpe at fylde lidt sand eller lignende i kammeret under højtaler-enheden så ladekammeret bliver lidt mindre, fyldes der for meget i, så vil også den lave mellemtone blive forstærket af hornet, som beskrevet ovenfor.

get me back to the horn menu page please!

get me back to the main index please!

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