Soundproofing a Gru...
 
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Radio Soundproofing a Grundig

 
bristle66
(@bristle66)
New V-Ratter Registered
Posts: 2

Warning - new member putting his toe in the water for the very first time.  Be gentle with me.

I have recently acquired a Concert Boy Luxus 1500 - one of Grundig's big beasts from the 1970s.  I know that views differ on the German sets but, to my uneducated ears, it sounds pretty damn good.  Most of the time.

The trouble is, now and then, it buzzes.  It's difficult to describe accurately but it sounds as though, at certain frequencies and independent of volume, the case resonates.  Presumably, this is linked to the fact that the case is made of plastic and not wood, like British sets of the period.  What, if anything, can be done to reduce the buzzing?  I'm reluctant to part with it if there is a relatively simple cure.  

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Topic starter Posted : 27/06/2022 7:10 pm
Jamie
(@jskinner97)
Noble V-Ratter Registered
Posts: 1601

Could pop a cloth over the rear of the speaker like they used to in some older extension speakers... or maybe rubber o rings used to insulate the speaker from the case under the screws?

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Posted : 27/06/2022 8:14 pm
PYE625
(@pye625)
Famed V-Ratter Registered
Posts: 4990

It can be like trying to cure an irritating rattle from a car's interior.... so many places where plastic meets.

One thing worth trying first is to be sure no screws have worked loose, including the 'speaker fixings. A loose fitting battery cover can also be a cause. Try operating the set with the rear cover removed and see if it stops. Obviously, if using mains power, avoid touching any exposed parts.

A possible cure is to use small quantities of a stuff called "black-tack" rolled into very tiny thin pieces and sandwiched between mating plastic seams of the rear panel and case. It is similar to blue-tack, but more flexible and sticky.

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Posted : 27/06/2022 9:08 pm
Reelman
(@reelman)
Busy V-Ratter Registered
Posts: 46

Welcome to the forum!

A rattle is always annoying but will be accented by the powerful bass boost Grundig used at this time to give the great sound. However they were good at putting thin felt between mating plastic case surfaces, check  it hasn’t fallen off. 

What can make it very difficult to locate a specific rattle is that it may come from an unsuspected source nearby.

A nice radio, I like the mechanical timer. My favourite period for Grundig sets.

Good luck.

Peter

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Posted : 28/06/2022 7:05 pm
bristle66
(@bristle66)
New V-Ratter Registered
Posts: 2

@reelman An update.

I've opened it up.  No sign of any felt.  Is is still possible to obtain it or an equivalent?

While the back was off, tightened the speaker screws.  One in particular was a little loose. I've also fitted sorbothane feet which have made a distinct difference.  It's a super radio.  Really pleased with it

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Topic starter Posted : 04/07/2022 2:50 pm
Will and Alex728 liked
Reelman
(@reelman)
Busy V-Ratter Registered
Posts: 46

It is just very thin felt, perhaps a hobby shop for supplies?

I would say that I find that Grundig sets of this period struggle with higher volumes because of their bass boost. All you can do is keep the volume reasonable or turn the bass down. Most Grundigs have a tone control that reduces treble at one end of travel and bass at the other. Now we know why!

Glad you are enjoying it.

Peter

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Posted : 07/07/2022 12:36 pm