hi thank you very much for the valuable link
I have the bad feeling that it is too much beyond my ability to understand Unfotunately i was not good at physics
During schools i had decent results also in lab activities (chemistry) I love instruments but i dont get the theory sadly
But i think i am beginning to see the light ...
Sats will be no problem I am sure of this They will have to cover "only" the range from about 300 Hz up
I understand that the 2 woofers solution is so much smarter than the one woofer solution
it seems that i will have to find 4 woofers in the end Identical
For a final speaker the effort will be justified completely
Now ... in parallel or series the two woofers ? 🤔🙂
I have the bad feeling that it is too much beyond my ability to understand Unfotunately i was not good at physics
During schools i had decent results also in lab activities (chemistry) I love instruments but i dont get the theory sadly
But i think i am beginning to see the light ...
Sats will be no problem I am sure of this They will have to cover "only" the range from about 300 Hz up
I understand that the 2 woofers solution is so much smarter than the one woofer solution
it seems that i will have to find 4 woofers in the end Identical
For a final speaker the effort will be justified completely
Now ... in parallel or series the two woofers ? 🤔🙂
I dont think Dual opposed subwoofer will work with crossover at 300 hz.
80 hz is better starting point and aim
For no higher than 120 hz.
Also Keep in mind crossing 120 hz, many subwoofer (typically those with heavy membrane and fat thick rubber surround Will Sound sluggish that High.
Generally parrallel is the Way to go. Aiming for 4 ohm.
In perfect World amp would double watt when ohm is halved. Such is not they case, but it is generally true when going from 8 to 4 ohm load.
Example is Hypex fusion.
80 hz is better starting point and aim
For no higher than 120 hz.
Also Keep in mind crossing 120 hz, many subwoofer (typically those with heavy membrane and fat thick rubber surround Will Sound sluggish that High.
Generally parrallel is the Way to go. Aiming for 4 ohm.
In perfect World amp would double watt when ohm is halved. Such is not they case, but it is generally true when going from 8 to 4 ohm load.
Example is Hypex fusion.
Here are a few points from that paper then.
They tested various wood-based materials and found that the Young's modulus (stiffness) was higher with birch plywood than particle board/chipboard. Stiffness was much less at high frequencies, though, (2-6 kHz) with almost all materials. In all materials, resonances had very high Q - in excess of 40.
The BBC speakers referred to in it (mainly LS3/5a, LS3/6) had cabinets made of 9mm birch ply, with two layers of bituminous felt glued on for panel damping. Front and back panels were screwed on to connecting fillets made of solid beech hardwood. Why this contruction? Because they measured the acoustic output of the cabinets in several planes, and found that this was best. They made an LS3/6 cabinet of 18mm birch ply, for example, and found that resonances were higher in frequency, higher Q, and more audible.
Measurements of damped and undamped cabinets don't show any noticeable shift in the frequency of resonances. But damping reduces amplitude.
They found that lower frequency resonances (below around 400 Hz) were less audible. For examples resonances in the 150-200 Hz range had to be maybe 10dB higher to be equally audible.
Hi thank you very much for this very valuable This makes things more complicated
in the meantime i have found something that i like as concept The old AR93
in this arrangement woofers vibes would be less impacting on the speaker structure ?
i see a lower xover frequency placed at 350 Hz I like this speaker a lot The concept i mean
it has also felts around the tweeter What a nice speaker
i am responsible for the confusion Forget the prefix sub I talked about subs because it is the more challenging test for a cabinet
i cant think of another situation when a cabinet is more stressed Faling from a balcony aside
thanks a lot again I do not sees amp as a big problem At least not before the speakers
i think that speakers have a bigger impact on the overall sound
i had a bad pair in the past They were sounding quite bad with different amps Then i discovered why
Since then i have avoided woofers with very high Qts They are a joke I wonder why they are even built
Hi thank you so much for this very valuable abstract I studied something at school but i did not catch a lot
i got a grade by copying from already solved problems How parrots talk I do not know if they know what they say
Fwiu these studies had the design and construction of a minimonitor as a goal ? a friend of mine had a pair of Rogers
they had no bass to speak of I mean they are not full range The evidence is when they playback a pipe organ at 90dB/2 meters
this is a very important point that explains why i was getting good bass from the speakers loaded with lead
for sure there were resonances But less audible ? i was playing a toccata e fuga and i was surprised by the difference with the unloaded speaker The pipe organ was more out of the box
I think that during development of the BBC LS35a, one cabinet sounded better than the others; on inspection the connecting fillets weren't glued in properly, resulting in being even better damped. Someone did a big listening test with different versions, and found the ones with screwed on backs sounded better than the ones with glued on backs.
I think the case you have in mind is in the document linked to in post #180? It mentions an LS3/6, made by one of the licensed manufacturers and sent to the BBC for testing. The cabinet resonances were particularly well damped - and as you say it turned out the fillets weren't fixed in properly.
Food for thought!
I havent done a sim but if you want for instance side mounted woofer, 150-200 hz is highest possible crossover. Lower is better.
Crossing at 300 hz is not subwoofer territory. It is midwoofer.
We find no commerciel
Subwoofer with such high crossover point.
Hey man, allow me to show you another means. I personally believe this is the best. Create a monocoque cab using 9mm PVC structural foam core and apply a couple of layers of medium biax glass. Forget about braces, form proper stations and stringers using Carlson Hulls. Have at lease two curved sides
Even better but less durable would be similar former machined from block structural foam, there won't be a deader cab then these
@ginetto61: I agree that very high Qts speaker is not the way to go. Several years ago I tested Eminence Alpha 15A in dipol/OB. Was high praised. In my entire life I have not since heard such bad bass. Fat. Slow. All bad adjectives.
I do think you put too much thinking in how to build a sub. Subwoofer is not difficult to build.
Dual opposed beats single woofer because of simple laws of force.
If you build single woofer from 25 mm HDF and brace it good, it will already be better than most subs you could buy.
But in the end even the most perfect and heavy subwoofer cabinet will not matter at all, if crossover is not perfect.
Bad crossover will ruin it all.
I do think you put too much thinking in how to build a sub. Subwoofer is not difficult to build.
Dual opposed beats single woofer because of simple laws of force.
If you build single woofer from 25 mm HDF and brace it good, it will already be better than most subs you could buy.
But in the end even the most perfect and heavy subwoofer cabinet will not matter at all, if crossover is not perfect.
Bad crossover will ruin it all.
Last edited:
Don't the woofers on the KEF Blades go up to 450Hz or something? They're side mounted, opposed.
KEF also has to cross high because of the small coax with flat, minimally diffraction from the suspension. If you do like KEF, you might get away with the higher cross-over. But with less optimal cabinets, larger midranges and maybe only single side woofers - you go lower in frequency before you cross, to avoid problems.
Always some kinda compromise 😉
interesting to know that at BBC rely on listening tests
Where the laser interferometry and distortion analyzers cannot reach the ear steps in
Maybe a super ear ... a batman ear
Anyway if bass and mid high have different requirements why not separate them i do not understand
woofers need stiffness ... mid and high need damping mass Two very different requirements
i found one commercial speaker the AR93 with a 350 Hz cut between the two back to back woofers and the midwoofer
anyway this is a very interesting issue Because it determines the range to send to the sats
Last edited by a moderator:
Hi thank you very much indeed for this valuable confirmation I really cannot think of an application where a high Qts woofer is good really And it is all quite understandable
in my case the magnet was quite weak and the cone moving mass quite high
Looking instead at low Qts woofer i have seen woofers with magnets big almost as the woofer frame
as they are quite expensive they must have other positive performance to justify their higher price And they have them
i would never go below 0.4 for Qts And i like also big coils
small coils do not tolerate big currents
thank you very much again
On this basis I am puzzled looking many high end subs using a single woofer (maybe with a passive)
i agree with the important advantage of the two woofers concept of course
All REL models have a single active woofer to name one brand
Maybe the two woofers solution could make the placement in the room more problematic ?
its sooo difficult to tame the moving mass of 18 inch drivers!!
moving ca. 200grams and you would need a sheer massive enclosure to withstand the movement.
I used opposite drivers cancelling each other out and composite of wood (12mm) and concrete (1cm) giving a dead response if you knock the box with your fingers although still being lightweight enough I can carry without help!
And this is for 150litre box and two lightweight (lowcost) 18 inch drivers in one box. No extra bracing inside.
With the movement cancellation the box is pretty quiet when putting your hand on the surfaces.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443474
moving ca. 200grams and you would need a sheer massive enclosure to withstand the movement.
I used opposite drivers cancelling each other out and composite of wood (12mm) and concrete (1cm) giving a dead response if you knock the box with your fingers although still being lightweight enough I can carry without help!
And this is for 150litre box and two lightweight (lowcost) 18 inch drivers in one box. No extra bracing inside.
With the movement cancellation the box is pretty quiet when putting your hand on the surfaces.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7443474
Passive XO on Tysen V2 is 450 Hz (woofers on the sides),
It should be noted that woofers/subwoofers have become synonomous in this thread. To go up that high is often a significant challenge for most/many true SUBwoofers
dave