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Multi-Way Conventional loudspeakers with crossovers

Is MDF  or plywood better for speaker cabinets?
Is MDF  or plywood better for speaker cabinets?
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Old 13th November 2019, 07:21 PM   #81
wiseoldtech is online now wiseoldtech  United States
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Quote:
Originally Posted by badman View Post
Hoooold up. Different power through a field coil will result in different effective motor strength, inductance, and other factors. I would expect wider bandwidth generally with lower coil current, certainly less damping at Fs and very likely a lower inductance.

That's not snake oil. Superiority of field coil may be more debatable.

Original field coil speakers have been around since the 1930's, having the coil used as a choke in the power supply, and as a hum-reducing system in those antique tube radios.
It's nothing "new", obviously.
And yes, the strength of the magnetic field depends on the power applied to it.


But alas, someone, somewhere, deamt up the idea to market these things again, and professes to claim all sorts of reasons to buy them.
Mostly to attract the buyers with "something different" to play with.



A marketing exec once told me a story....
"if you give a child a set of blocks, those toys made of wood with letters and numbers on them, the child will be fascinated by them, naturally.
And not having the knowledge or knowing the background or reasons of them, will be amused.
The company has now profited from the purchase, and the parents are satisfied to keep the child "busy".
All is well.
The same thing goes for marketing something that the public is not aware of in the current era, be it an old design or whatever."


Like today, how many people (perhaps millenials) are aware that field coil speakers are "old school" devices from the 1930's?
To them, it's something new and wonderful - made that way by marketing hype.
So, out of curiosity, they buy those things, believing whatever claims made will gain them satisfaction.
And the company profits...


It's all BS to me, listen, I've been around for 66 years, seen it all by now, and serviced people's broken audio/video stuff professionally for at least 45 years.
That's why I sit back and laugh at all the "claims," "trends," and goofy marketing going on these days.
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Old 13th November 2019, 07:26 PM   #82
planet10 is online now planet10  Canada
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Is MDF  or plywood better for speaker cabinets?
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Originally Posted by wiseoldtech View Post
Original field coil speakers have been around since the 1930's, having the coil used as a choke in the power supply
I’ll have to snap a pic of th elate-30s one i have downstairs on my table as an example.

Quote:
But alas, someone, somewhere, deamt up the idea to market these things again
Alas, historically they went away because fixed magnets became much less expensive. FC have their theoretical advantages, the only pair i ever heard were very flawed (but i doubt it was the FC). As a frugal-phile(tm) the huge price make sit unlikely i will have more pairs to play with. I’ll live vicariously with DJN.

dave
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Old 13th November 2019, 07:49 PM   #83
bentoronto is offline bentoronto  Canada
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Is MDF  or plywood better for speaker cabinets?
Quote:
Originally Posted by wiseoldtech View Post
Original field coil speakers have been around since the 1930's, having the coil used as a choke in the power supply, and as a hum-reducing system in those antique tube radios.
It's nothing "new", obviously. And yes, the strength of the magnetic field depends on the power applied to it...
The more magnet strength the better. Sure, you can post a hocus-pocus sim showing an exception, but maybe you need to re-think how sims work and why their "answer" isn't always peak SQ. Ditto for the "benefits" of lowering the supply to a field coil if that is an option on your speakers.

Field coils disappeared 50 years before it became feasible to deliver big low-ripple DC currents using solid-state circuits. Times have changed.

With a field coil, you have flexibility in various ways and the potential for making great magnets. While I am no fan of the ancient cone driver concept, a field coil makes a lot of sense to me.

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Last edited by bentoronto; 13th November 2019 at 07:52 PM.
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Old 13th November 2019, 08:31 PM   #84
lowmass is offline lowmass  United States
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Home depot PVC sheets. very well damped. Someone needs to try this stuff. 1/4, 1/2, 3/4 " available
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Old 13th November 2019, 08:53 PM   #85
scottjoplin is offline scottjoplin  Wales
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Originally Posted by planet10 View Post
KEF was also the company that grommet mounted the midrange in the 105 to isolate it from the box. Measured good, but didn’t sound as good as removing the grommets and properly tightening the bolts. I am always suspicios of suff that KEF “measures” into existance.
This might interest you Issues in speaker design - 2 The KEF midrange is mentioned at the end, a magnet clamping method was used to mount it
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Old 14th November 2019, 02:50 AM   #86
zman01 is offline zman01  Bangladesh
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Is MDF  or plywood better for speaker cabinets?
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Originally Posted by lowmass View Post
Home depot PVC sheets. very well damped. Someone needs to try this stuff. 1/4, 1/2, 3/4 " available
Use it as the middle layer in a CLD type application?

Or are you proposing to use it to line the inner walls, like bitumen or sound deadening materials?
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Old 14th November 2019, 03:14 AM   #87
Steve Duffy is offline Steve Duffy  Australia
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I use 18mm Formply, the black coating is durable and the speakers don't need painting
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Old 14th November 2019, 11:01 AM   #88
maty tinman is offline maty tinman  Spain
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Quote:
The whole video is worth the time but 26:00 to about 45:00 is on this subject. CLD for the win.
Youtube: World's Second Best Speakers!

Click the image to open in full size.

Picture about 43:16: YouTube
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Old 14th November 2019, 01:30 PM   #89
lowmass is offline lowmass  United States
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Originally Posted by zman01 View Post
Use it as the middle layer in a CLD type application?

Or are you proposing to use it to line the inner walls, like bitumen or sound deadening materials?

I was thinking making the entire cab out of it. Its a rigid dense and heavy "board". There may be an issue with its structural properties, im not sure. It may "flow" over time and strain??

Maybe will need some structure in the form of braces inside made of wood?

Not sure what to do BUT it is much better damped than any wood and would love to see what can be done with it.
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Old 14th November 2019, 07:45 PM   #90
djn is offline djn  United States
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This is all great discussion but I am taking a chance on the drivers already so I'll stick to Birch plywood well braced and veneered with bamboo. The PVC looks good but it is not sold here in Albuquerque.

Also, I run 4 subwoofers to handle the low end and don't listen really loud anymore so the braced plywood should work just fine for my situation.
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