Is your 26mm MDF speaker cabinet resonating like a church bell despite substancial bracing - try this CLD sandwich technique!
This should reduce any nasty peaks and vibrations that might show up in later measurements.
I did not do the whole inside because volume is low as it is. I did not enjoy reducing the depth of the cabinet even more, but something had to be done about this ringing. Bracing is there, and as much as I dare to have, not to create separate compartments within the compartment.
Inspired by the excellent sound of Devore Orangutan O/96, I only put a patch of recycled denim damping material behind each driver, and a small one on the bottom. I don’t want it unaturally dead. More like Schrödinger’s cat dead.
I will avoid polyfill, but might throw in a used merino wool sweater.
Here is before and after, of me finger tapping my woofer cabinet. No music yet, but I expect crap since these cabinets are too small for two pairs of W26FX002 woofers.
References:
Where did I get this idea? Scroll to the last experiment.
This should reduce any nasty peaks and vibrations that might show up in later measurements.
I did not do the whole inside because volume is low as it is. I did not enjoy reducing the depth of the cabinet even more, but something had to be done about this ringing. Bracing is there, and as much as I dare to have, not to create separate compartments within the compartment.
Inspired by the excellent sound of Devore Orangutan O/96, I only put a patch of recycled denim damping material behind each driver, and a small one on the bottom. I don’t want it unaturally dead. More like Schrödinger’s cat dead.
I will avoid polyfill, but might throw in a used merino wool sweater.
Here is before and after, of me finger tapping my woofer cabinet. No music yet, but I expect crap since these cabinets are too small for two pairs of W26FX002 woofers.
References:
Where did I get this idea? Scroll to the last experiment.
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Yes it works.
Seen the mentioned video before.
But there are better suited materials then usual silicone.
Green glue would be the most common i guess, for applying in that fashion.
EAR isodamp and isoloss LS , "vinyl damping sheets in precut sizes, or larger mats etc.
Anyways a interesting demonstration 🙂
Seen the mentioned video before.
But there are better suited materials then usual silicone.
Green glue would be the most common i guess, for applying in that fashion.
EAR isodamp and isoloss LS , "vinyl damping sheets in precut sizes, or larger mats etc.
Anyways a interesting demonstration 🙂
Devore Orangutan?? lol you mean the really overpriced speaker with large thin baffle
and no bracing.
The magical wood and absorption material debates that get beating
like a dead horse around here.
absorption material is absorption material. poly and rockwool
both work fine.
MDF and plywood both work fine and you add braces.
woo hoo....
one guy thinks a box is too dead, then another guy says its fine.
you can make a box too dead with poly or rockwool.
put some in, take some out. not rocket surgery
absorption helps mainly with midrange frequencies.
bass waves too long. need to tame down bass.
that is usually when rockwool comes into play.
even dirt basic models show you the effect on
impedance curve or cone movement. by changing
absorption in the model.
and no bracing.
The magical wood and absorption material debates that get beating
like a dead horse around here.
absorption material is absorption material. poly and rockwool
both work fine.
MDF and plywood both work fine and you add braces.
woo hoo....
one guy thinks a box is too dead, then another guy says its fine.
you can make a box too dead with poly or rockwool.
put some in, take some out. not rocket surgery
absorption helps mainly with midrange frequencies.
bass waves too long. need to tame down bass.
that is usually when rockwool comes into play.
even dirt basic models show you the effect on
impedance curve or cone movement. by changing
absorption in the model.
The best you can do is use dissimilar materials with differing physical properties, look at what they do for room acoustics. Or vandersteens CLD with 3 different materials and viscoelastic layers between etc.
You can also use better materials like densified wood with phenolic resin (panzerhols, permali deho etc.) That has a much higher damping factor then ply or mdf, just the price that will make you cringe.
And so on
The term 'unnaturally' is suggesting a conclusion has been drawn. I wouldn't agree with the conclusion but I'm sure many of us have faced the issue you're talking about and struggled with it.
And with constrained layer, the science only works
if it is more soft or elastic.
many use hard rubber or non elastic materials.
and its a waste of time. just adding mass.
more extreme test have been done with
thin wall and thick wall enclosures.
with extremely high pressure speaker systems
800 to 1000 watts. And SPL difference to losses
was 1 to 2 dB.
Seen Youtube videos of really large poorly braced cabinets.
and instead of actually bracing the cab.
They add some magical expensive goop. and swear they
hear a difference.
People like they idea of some magical thing.
that makes speakers sound better lol.
If I add 200 dollars worth of goop my 80 dollar
fullrange speaker just blooms with incredible
quality
Or people mount 300 dollar speakers on thin baffles.
And as long as it has bookmarked Veneer on it...
its amazing !!!! the 300% price mark up justifies it.
if it is more soft or elastic.
many use hard rubber or non elastic materials.
and its a waste of time. just adding mass.
more extreme test have been done with
thin wall and thick wall enclosures.
with extremely high pressure speaker systems
800 to 1000 watts. And SPL difference to losses
was 1 to 2 dB.
Seen Youtube videos of really large poorly braced cabinets.
and instead of actually bracing the cab.
They add some magical expensive goop. and swear they
hear a difference.
People like they idea of some magical thing.
that makes speakers sound better lol.
If I add 200 dollars worth of goop my 80 dollar
fullrange speaker just blooms with incredible
quality
Or people mount 300 dollar speakers on thin baffles.
And as long as it has bookmarked Veneer on it...
its amazing !!!! the 300% price mark up justifies it.
Usually I over do the stuffing out of fear and ignorance. My previous cabinet were made of thin OBS boards, but I treated them so heavily with lots of bracing, CLD silicone sandwich, thick plaster and many many layers of acrylic paint - my very own magical goop. They became almost completely dead. I think the deadness was only positive really, but this time I want to try to liven things up a bit, and knowlingly make it a bit more resonant. I took care of it in the worst places, I think.
The denim damping material made a big difference, and I might add some more in the top and bottom corners. It has adhesive in the back and become a sort of light sandwich layer as well, made of denim, glue and wood underneath.
In my experiment I wanted to find a way to prevent overstuffing. I am not really qualified to say which is better, I am just trying different things when I get the chance. In this case the difference can be heard even on youtube.
Since I dislike the having mineral wool flying around in the air I end up using plastic foam, which has worse acoustic qualities. Denim was a nice surprise and works very well.
Hornresp can simulate damping material thickness, but I don’t see much of a difference with or without.
Recycled Denim, Wool, Poly, Rockwool
Foam.
all work.
Improving midrange reflections all it does.
Im the same , 3 way with mid chamber.
Stuff it to holy heck.
Bas Reflex, line it.
Long parallel walls like a tower.
Really a peeve with me.
People put the port way at the bottom.
So no absorption can be added to the " Uh Oh"
lower section. That is when Rockwool can help.
Very large cabinets with large long parallel walls.
that is when bracing and stuffing is actually gonna
do something.
bookshelf speaker with a 5" or 6"
toss some poly in there call it a day.
some magical filler aint gonna fix a 5"
speaker.
Im all about good bracing.
High SPL, Double the baffle
brace it.. the end
tower, stuff the krap out of the bottom.
the rest...line it
Foam.
all work.
Improving midrange reflections all it does.
Im the same , 3 way with mid chamber.
Stuff it to holy heck.
Bas Reflex, line it.
Long parallel walls like a tower.
Really a peeve with me.
People put the port way at the bottom.
So no absorption can be added to the " Uh Oh"
lower section. That is when Rockwool can help.
Very large cabinets with large long parallel walls.
that is when bracing and stuffing is actually gonna
do something.
bookshelf speaker with a 5" or 6"
toss some poly in there call it a day.
some magical filler aint gonna fix a 5"
speaker.
Im all about good bracing.
High SPL, Double the baffle
brace it.. the end
tower, stuff the krap out of the bottom.
the rest...line it
And good point with a reflex cabinet
what material is used is more justified. Because yes exactly you dont want material flying out the ports.
And as far as the old practice of using home insulation or pink insulation.
works fine as well.
Except with a reflex blowing that material out. Not good for the lungs.
Sound pressure when it passes through the small hairs of absorption material.
Creates friction, turns into heat.
All it is , pressure is removed by turning to heat.
So actually the easier it is for pressure to pass through the better.
Then you want as many hairs as possible for the friction.
Rockwool is really dense, so it is more effective for low frequency.
Higher frequency where absorption is actually useful.
actually wont pass through rockwool easy.
Most subs aren't even stuffed. common wool or poly
really not enough. People seem to be confused.
Rockwool more effective for bass, since bass rolls through anything.
Otherwise for midrange good old poly, lots of hair structure for friction
easy to pass through. Compared to fiberglass insulation. same thing.
Poly is used, non toxic not fiberglass bad for lungs and skin irritation.
As mentioned with long long parallel walls creating bass resonance.
Then yes Rockwool, since it stands a change at doing anything.
At low frequency.
People talking about over stuff sound. MI industry knows it well.
Plenty of unstuffed boxes with horrible midrange peaks.
The real reason to line a cab. Some guys like the woody box sound.
Because the reflected sound makes it sound louder.
otherwise in measurement its full of peaks, that a Hi Fi guy would
want to get rid of
Something I do not understand is what the point if you knock the cabinet from the outside and listen the sound from the outside (and also with open cabinet) ?
You do not care of the sound made in that direction, no ?
The only test that matters is the vibration measurement of the cabinet when applying a sweep or something similar, no ?
About the CLD : does the internal panel that vibrate on a viscoelastic layer, should not be very thin and stiff in order to vibrate. I.e. free of contacts with the outside of the inteernal corners in order that layer can vibrate and not as are made most of the bracing that has tigth and strong contact with the cabinet ? Imho, from a theorical point of view, @mbrennwa made it the rigth way on his OMSC project. Surely the damping layer has to be made very thin,as said @TNT. Certainly thinner than the 1/2 mm, with no free spaces... Not easy but surely feasible for perfectionists diyers. That's one of the CLD, i.e. mass spring mass damping effect.
The op technic of a small thick square of wood is also seen with Sonus Faber iirc.
The sheet that is freely hanged behind the driver was seen with the Onken cabinet with a sheet of thick wool felt not a lossy Denim isolation sheets made for home thermic isolation.
You do not care of the sound made in that direction, no ?
The only test that matters is the vibration measurement of the cabinet when applying a sweep or something similar, no ?
About the CLD : does the internal panel that vibrate on a viscoelastic layer, should not be very thin and stiff in order to vibrate. I.e. free of contacts with the outside of the inteernal corners in order that layer can vibrate and not as are made most of the bracing that has tigth and strong contact with the cabinet ? Imho, from a theorical point of view, @mbrennwa made it the rigth way on his OMSC project. Surely the damping layer has to be made very thin,as said @TNT. Certainly thinner than the 1/2 mm, with no free spaces... Not easy but surely feasible for perfectionists diyers. That's one of the CLD, i.e. mass spring mass damping effect.
The op technic of a small thick square of wood is also seen with Sonus Faber iirc.
The sheet that is freely hanged behind the driver was seen with the Onken cabinet with a sheet of thick wool felt not a lossy Denim isolation sheets made for home thermic isolation.
It is actually sealed. I tried ported but the Seas W26FX002 has so much bass, that I am trying a sealed cabinet. The peak in my room is at 43 Hz, and the sealed should be good down to 50Hz. Luxury problem. Need to build smaller subs to reduce bass.
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I will do further testing and continue with other ideas if this is not good enough. I used thin sheets of plywood inside because the volume is already quite small.
Wool is a great option. Would have used it if I had it.
Sealed is were rockwool could help, or if boomy reflex overstuffing helps that.
Or many tune high or too high making the transfer function " flat"
so the High Q over emphasis the bass.
Another option is tuning very very low so transfer function is similar to sealed.
But the reflex tuned low actually helps with cone control , instead of unloading.
Or extended bass shelf, which most people dont understand.
The box is large for low Q and the tuning is also below Fs not above.
Really depends on mechanical aspects of the driver. If Vas is large it wants a big box.
And too many get caught up making transfer function look flat. When Reflex does give
" more bass" But more important for mechanical property not trying to make a " Flat"
response because a speakers relation to filter responses has nothing to do with FR
Mainly about the suspension and the right volume, far as how much bass you get
a speaker is what a speaker is.
Or many tune high or too high making the transfer function " flat"
so the High Q over emphasis the bass.
Another option is tuning very very low so transfer function is similar to sealed.
But the reflex tuned low actually helps with cone control , instead of unloading.
Or extended bass shelf, which most people dont understand.
The box is large for low Q and the tuning is also below Fs not above.
Really depends on mechanical aspects of the driver. If Vas is large it wants a big box.
And too many get caught up making transfer function look flat. When Reflex does give
" more bass" But more important for mechanical property not trying to make a " Flat"
response because a speakers relation to filter responses has nothing to do with FR
Mainly about the suspension and the right volume, far as how much bass you get
a speaker is what a speaker is.
It depends of what you try to achieve. Arez's comment about room acoustic is not entirely false neither entirely true too:
With room acoustic you can see CLD with different layers ( example ba13/resilient material/ ba13/ba21) but it is most of the time used in double leaf configuration ( same sandwich used for both walls which do not touch - gap between them).
The different density of material does their thing on different frequency range ( ba13 on medium/ ba13-ba18 compound on lows) with resilient material doing it's own thing through sheer deformation ( transform movement into heat).
Doubling the walls and leaving a gap makes it even more effective.
In case of loudspeakers it is difficult to do.
CLD bracing is nothing new. Earl Geddes presented his view on it in here ( he's gone from CLD to CLD bracing during his loudspeaker's line life), it have been used by Tannoy on their pro range ( DMT) and been fully documented by Kef in their whitepapers ( Ls50, R range,...).
If you look enough in there is even links to patents about the different use you can make of them.
^ yes for single walled and depending of materials.
It is what have been used by some flagships loudspeakers. Let me find the Sony patent ( iirc) and i'll link it.
Edit: here it is,
https://patents.google.com/patent/US5949033A/en
But depending on material and frequency of interest it can be different ( eg: to dampen metal sheets you can find larger resilient material and very thin aluminium).
Cld can be confusing because there is multiple way to implement it.
Here is the patent about CLD brace:
https://patents.google.com/patent/US7270215B2/en
It is what have been used by some flagships loudspeakers. Let me find the Sony patent ( iirc) and i'll link it.
Edit: here it is,
https://patents.google.com/patent/US5949033A/en
But depending on material and frequency of interest it can be different ( eg: to dampen metal sheets you can find larger resilient material and very thin aluminium).
Cld can be confusing because there is multiple way to implement it.
Here is the patent about CLD brace:
https://patents.google.com/patent/US7270215B2/en