Speakers cabinet _ knock on wood test

But when they sound dead it is really a case of a wide (lowQ), LF resoance that oozeds time-smeared crap at LF.

dave
They is me, and I guess you could hear a jelly resonate, but I couldn't. The conservation of energy suggests a smearing, but that applies to many solutions. Wadding is good with HF, but LF damping materials is about weight. To categorise things roughly
 
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If you want to be anal you could tune it such that modern music. (ie recordings) does not provide energy at those frequencies. But a general target of, as high is possible, is good enuff for me,
I see But i have watched a video of a company using aluminum sheets for their speaker cabinets They agree of course on the fact that metals ring but the ringing is very little higher in pitch and quite easy to suppress with some damping mat strategically placed
On another hand you can get a stiffness impossible to achieve with woods
To bolt the woofer to thesteel frame one would have to cleverly design the basket.
i think that this is a very important and often overlooked topic The basket design Expecially the outer ring where the bolts are used
Imho that ring should be big to allow for a better match with the front baffle
this is a good example of what i mean a large front ring on the basket with an increased contact area between driver and baffle

1738662070620.png


instead is usually very narrow I do not understand why
A good target, up to 500Hz bandwidth, 100Hz XO.I tend to prefer a larger transition area for the XO, i’d be looking for 1kHz+ for a sub going as high as 100 Hz.
dave
thank you very much after knowing of the Xmax issue i would use a small woofer 4-5" for the midrange up to possibly 3kHz
the woofers usually have higher Xmax than true midrange of the same size and used from 4-500Hz should not show any distortion
also full range used as midrange could be interesting Unfortunately most of them show peaks at around 10kHz
i guess that some notch filter can cure this and maybe a tweeter could not be necessary Just a full range from 500Hz up and done
 
With a little thought it should be perfectly obvious why cuboid boxes need so much complex bracing to reduce panel flexing so they work acceptably well - they are the wrong shape to start with!
Hi i agree without problem It is the construction that becomes challenging
tell me how many subs are not cuboid There must be at least one good reason to use a cuboid cabinet
To my mind it is rather like building a bicycle with a rubber frame and then having to add all sorts of stiffening elements to make it rideable. Why does everyone seem to take this route when building DIY speakers?
probably because it is simpler easier
I can understand that slightly more complex woodwork is beyond the capability of some, but it saddens me that there is so much Monkey-See-Monkey-Do in many different hobbies, when there is an almost limitless quantity of inspiration and ideas to be found on the interweb using just a tiny bit of lateral thinking - thinking outside the box, pardon the pun...
i agree again But i believe that a well designed and built bracing can eliminate most of the problem
in my mind something like the bass bin of the old B$W 801 S2 could be taken as a reference

https://www.stereophile.com/content/bw-matrix-801-series-2-loudspeaker-measurements

1738663400260.png
 
Everything resonates. If the (potential) resonances is not excited it is as if there wasn’t one. Your sub operating to 400 hz or so (4th order filter), and the box resoances are >500 Hz there is nothing to get them going.
dave
I see still i will carry out the water test on the bass cabinet It is so easy to do maybe using a high amplitude sweep tone covering the decided working range of the woofer No ripples on the water excellent cabinet Job done
 
Simplicity. That's about it - they even use more material than a cleverly designed enclosure...
🙂👍
My basic rules are; Subs - rigidity,
here is the challenge The main and only one imho
Mids - well-damped.
absolutely not a problem Thick mdf would do just fine If not enough lead can help a lot
The BBC papers on enclosure construction are still relevant today.
if they are based on physics principles i guess so
i have no chance to understand principles But i can do some measurements
this is why when i read a review on speakers i go almost immediately to the lab report
 
The basket design Expecially the outer ring where the bolts are used
Imho that ring should be big to allow for a better match with the front baffle

The outer bezel is but one part. Ideally we would be able to bolt the other end of the driver to the box as weell.

We don’t get to design our own baskets, but in this case a (couple?) hundred of these were made:

PR2 Bass Unit.jpg


The basket envelopes the magnet assembly, so that the magnet is not puloled off when a bolt reaches thru the pole-piece and bolts to the cabinet. nSame could also be used to create a push-push assembly.

pushpushPR2.gif


dave
 
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Sounds like you are headed for a npoor result. That is a recipe for pushing ringing LOW… and that is a route that makes littler to no sense… it is a subwoofer/woofer.

dave
no not for the woofer enclosure For the mid and high drivers enclosure There will a rigid body (woofer box) below a dumped head (mid and tweeter box)
If i have learned one thing is that the requirements for low and mid high differ This is why i would like to keep things separated
this will also allow to try different solution for bodies and heads more easily
Who said that a speaker must be a monolith ?
 
The outer bezel is but one part. Ideally we would be able to bolt the other end of the driver to the box as weell.
We don’t get to design our own baskets, but in this case a (couple?) hundred of these were made:

View attachment 1417005

The basket envelopes the magnet assembly, so that the magnet is not puloled off when a bolt reaches thru the pole-piece and bolts to the cabinet.
Hi thank you for the very interesting information i was only noticing that the basket edge is usually very narrow also for big units
A wider edge could provide a better contact of the basket with the front baffle
nSame could also be used to create a push-push assembly.

pushpushPR2.gif


dave
I understand that this arrangement provides significant advantages for vibrations management
But i reall would like to use just one woofer and front firing like the vast majority of the subs around
I am only looking for something decent sounding I see even the bass reflex a complication
There are some sealed speakers with a nice bass I would trade extension for a better control