What Makes a Loudspeaker Musical?

[Rutger]

My experience is the same as yours regarding making heavy loudspeaker cabinets - they sound less tuneful than lighter and stiffer cabinets.

That's 2 different parameter changes there - lighter and stiffer. A high mass cabinet can be stiff, and is highly likely to be so. Using the same materials, the lighter cabinet will be less stiff. However, it could potentially be stiffer than the high mass cabinet if the material is changed. But light and stiff materials tend to have very high frequency resonance, so likely to be in the vocal range which will bring significant problems in terms of emotional connection to the music. They can, of course, be damped to an extent, but that usually adds mass! Its a very circular discussion :)

Resonanses at higher frequencies with high Q releasing its energy faster sounds better , its easier to follow the tune .

In my opinion it also sounds better if those resonanses ( energy ! ) can be transported quickly from the cabinet to the floor using spikes.

[Rutger]

Possibly. I’ve a feeling that each additional kg, regardless of its role or purpose, reduces musicality due to the time it takes for vibrations to decay, thus smearing transients. However, increasing the size of the enclosure, without increasing its mass, leads to a less structurally stable enclosure, possibly also leading to smeared transients. So from a transient response perspective a small, lightweight enclosure may be best. But. As we know, small enclosures don’t usually produce enough bass for a balanced sound on most types of music. I’m hoping that a larger, but no more massive enclosure, positioned close to a wall will produce a speaker with more bass without losing the life in the music.

You could try to build a stiff thin wall loudspeaker cabinett ( low weight ) but use different thickness on every opposite wall in the speaker to avoid tunefork effects . You could use 12 mm and 16 mm mdf for this. You will probably be surprised by the result.

My experience is the same as yours regarding making heavy loudspeaker cabinets - they sound less tuneful than lighter and stiffer cabinets.

If using raw mdf, one must paint the inside of the cabinet with 50% water and 50% wooden glue or use ordinary paint - mdf leak air and will sound worse If not sealed with paint or glue, especially if its a closed box.

I’m actually actively trying to encourage the tuning fork effect (if I understand you correctly). Research has shown that resonances with a high Q and narrow bandwidth are less audible than resonances with a lower Q and a wider bandwidth. I want all the resonances to align harmonically. This breaks all the rules, I know, but who knows, it might actually work!

What happens if you have a tunefork resonanse from the cabinet exactly at the frequency of a musical tone ?

Remember you can always build a stiff, high Q resonating cabinet without tunefork effects if you use different thickness on every opposite wall in the speaker, also the sidewalls . This will give a better sound result.

Im convinced that the reason a very stiff and thick baffle sounds better is not only because of the stiff material - it also minimizes the resonanses from the cabinet because the opposite wall, the back of the speaker is usually thinner with a different resonance frequency.

Building a loudspeaker with the same wall thickness and equal size of every panel is probably the worst sounding cabinet one can build .

[chefren]

I've never designed or built a loudspeaker in my life, but I do know that any material will damp resonances at some frequencies. It's also pretty well known that symmetry is not a must for speaker cabinets for performace reasons, they are done more for cost reasons.

This makes me thing that experimenting with combining different materials and/or material thicknesses and rejecting the need for everything to be symmetrical may provide interesting and useful results. Although a lot of experimentation is probably needed which is a lot of work if that means building a lot of extra speaker cabinets. I think the Russel K speakers at least try to do this, replacing internal dampening with selective bracing etc. to break up resonances instead. Maybe some lightweight material like Balsa could be used to provide some internal diffraction inside a cabinet without adding weight?

Sandwiching in different ways is also interesting, for example Harbeth veneers also their MDF cabinets with a lower cost veneer from the inside for performance reasons. I remember a Hifi World article on a Peter Comeau project, where he experimented with a sandwich of two thin MDF layers sandwiching a particle board layer. A lot of different interesting options can be found for example on this page: https://kerfkore.com/blog/all-about-lig ... ch-panels/

Embracing resonances in an undamped cabinet is probably challenging as those resonances will make their way back into the speaker drivers. Trying to isolate the tweeter may be interesting in these cases even though damping would otherwise be avoided, as I would think significant resonances from the woofer via the cabinet would cause more extra movement in the tweeter compared to a lossy mounting of the tweeter, because the tweeter does not put out enough force to move itself in the way a woofer will.

[Spannko]

What happens if you have a tunefork resonanse from the cabinet exactly at the frequency of a musical tone ?

Remember you can always build a stiff, high Q resonating cabinet without tunefork effects if you use different thickness on every opposite wall in the speaker, also the sidewalls . This will give a better sound result.

Im convinced that the reason a very stiff and thick baffle sounds better is not only because of the stiff material - it also minimizes the resonanses from the cabinet because the opposite wall, the back of the speaker is usually thinner with a different resonance frequency

I’m not exactly sure what will happen tbh other than I should learn something.

Thanks for the different wall thickness suggestions. I’ll definitely try it at some point.

[Spannko]

I've never designed or built a loudspeaker in my life, but I do know that any material will damp resonances at some frequencies. It's also pretty well known that symmetry is not a must for speaker cabinets for performace reasons, they are done more for cost reasons.

This makes me thing that experimenting with combining different materials and/or material thicknesses and rejecting the need for everything to be symmetrical may provide interesting and useful results. Although a lot of experimentation is probably needed which is a lot of work if that means building a lot of extra speaker cabinets. I think the Russel K speakers at least try to do this, replacing internal dampening with selective bracing etc. to break up resonances instead. Maybe some lightweight material like Balsa could be used to provide some internal diffraction inside a cabinet without adding weight?

Sandwiching in different ways is also interesting, for example Harbeth veneers also their MDF cabinets with a lower cost veneer from the inside for performance reasons. I remember a Hifi World article on a Peter Comeau project, where he experimented with a sandwich of two thin MDF layers sandwiching a particle board layer. A lot of different interesting options can be found for example on this page: https://kerfkore.com/blog/all-about-lig ... ch-panels/

Embracing resonances in an undamped cabinet is probably challenging as those resonances will make their way back into the speaker drivers. Trying to isolate the tweeter may be interesting in these cases even though damping would otherwise be avoided, as I would think significant resonances from the woofer via the cabinet would cause more extra movement in the tweeter compared to a lossy mounting of the tweeter, because the tweeter does not put out enough force to move itself in the way a woofer will.

Nearly all materials resonate and damp, depending upon the frequency. Traditional loudspeaker materials (mdf, plywood, chipboard) do this in a very nonlinear fashion which may be the reason they don’t seem to resonate in a harmonious way. So we have the possibility of harmonic skewing due to the material choice, time smearing due to any mass which is greater than necessary or unwanted resonance due to an over flexible, lightweight and undamped enclosure. Who said loudspeaker design was easy!