Dynatron Speakers

amplifiers, receivers and loudspeakers
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sjw+123
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Dynatron Speakers

Post by sjw+123 » 03 Dec 2019 19:44

Hi all,
just acquired a set of 1973 Dynatron LS4038 speakers-the 'big boy's' of the range!
On removing the grilles to check drive units a fair amount of black foam like debris fell out and was
also trapped in the cloth grille cover? Has anyone an idea what this could be.All driver surrounds see intact.
Thanks in anticipation,Stephen.

AsOriginallyRecorded
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Re: Dynatron Speakers

Post by AsOriginallyRecorded » 03 Dec 2019 20:14

This is just a guess, but some speakers use a sort of expanded foam as a cushioning/filtering material on the inside side of the grills, and I have recollection of finding the same odd black gritty dust inside the speaker cabinets. Mostly messy and inconvenient I believe. Many of the materials used new in vintage gear has reached it's limit of longevity unfortunately. Better replacements are usually available. If they still sound okay, I would suggest this is the answer. [-o<

lenjack
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Re: Dynatron Speakers

Post by lenjack » 03 Dec 2019 22:44

Gently press a finger against one of the surrounds and see if it collapses. This may be a foam surround that is turning to dust.

sjw+123
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Re: Dynatron Speakers

Post by sjw+123 » 04 Dec 2019 05:29

Ok,thanks for replies,very grateful.
I had a theory that a foam lining might have been used as the grilles are double lined. Can anyone confirm this?
Stephen

AsOriginallyRecorded
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Re: Dynatron Speakers

Post by AsOriginallyRecorded » 04 Dec 2019 07:58

I have only owned one pair of Wharfedale speakers, and they had rubber surrounds, so deterioration was not an issue. In many cases they can be reconditioned for many more years use. It should be readily apparent whether the surrounds are rubber or not, especially on the bass woofers. Generally, a quite gentle application of a signal to the woofers will destroy any foam woofer in such condition.The possible use of Wharfedale components in the Dynatrons is the only reference I could find on google indicating speaker construction. Someone familiar with Dynatron speakers will have to jump in for more information. This is often the problem with limited production....limited information. #-o

Chiltern
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Re: Dynatron Speakers

Post by Chiltern » 04 Dec 2019 10:06

sjw+123 wrote:
03 Dec 2019 19:44
Hi all,
just acquired a set of 1973 Dynatron LS4038 speakers-the 'big boy's' of the range!
On removing the grilles to check drive units a fair amount of black foam like debris fell out and was
also trapped in the cloth grille cover? Has anyone an idea what this could be.All driver surrounds see intact.
Thanks in anticipation,Stephen.
That nearly always happens with these speakers. Yes it was a thin foam layer between the cloth cover material and the board. Same construction with the range of Goodmans speakers of the era, probably there to reduce the movement of the cloth, given the size of the bass driver.

Alan

sjw+123
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Re: Dynatron Speakers

Post by sjw+123 » 04 Dec 2019 10:23

Many thanks Alan,as I suspected.
Thanks to all who contributed, Stephen.

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