Distortion on Grundig Concert Boy - UK Vintage Radio Repair and Restoration Discussion Forum

Timvintage · 25th Apr 2017, 5:18 pm

Hi everyone, I have a Grundig concert boy, which has a lovely tone, however, the sound starts to distort, particularly the base, once you start to turn the volume up past a low level. I read somewhere on the forum that this problem can be sorted by putting some felt somewhere inside the case, can anyone give some more information on this please? I'm wondering exactly where to put the felt? Any help would be very much appreciated, the more info the better, thank you very much, Tim

Edward Huggins · 25th Apr 2017, 6:02 pm

Are you trying to describe an acoustic resonance or electronic distortion? These should not need any acoustic treatment using felt and I suspect that the output transistor voltages need testing. When you say "base", I assume you mean Bass not the bottom of the cabinet?

Mike Noble · 25th Apr 2017, 10:09 pm

I have a Concert Boy which started to distort as the volume was increased and was cured by replacing the bridge rectifier. In fact the rectifier must have been faulty for a while to a lesser degree as after changing the rectifier I needed to reduce the Bass setting.

25th Apr 2017, 5:18 pm	#1
Timvintage Pentode Join Date: Jun 2014 Location: Bristol, UK Posts: 143	Distortion on Grundig Concert Boy Hi everyone, I have a Grundig concert boy, which has a lovely tone, however, the sound starts to distort, particularly the base, once you start to turn the volume up past a low level. I read somewhere on the forum that this problem can be sorted by putting some felt somewhere inside the case, can anyone give some more information on this please? I'm wondering exactly where to put the felt? Any help would be very much appreciated, the more info the better, thank you very much, Tim

25th Apr 2017, 6:02 pm	#2
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,340	Re: Distortion on Grundig Concert Boy Are you trying to describe an acoustic resonance or electronic distortion? These should not need any acoustic treatment using felt and I suspect that the output transistor voltages need testing. When you say "base", I assume you mean Bass not the bottom of the cabinet? __________________ Edward.

25th Apr 2017, 10:09 pm	#3
Mike Noble Pentode Join Date: Oct 2005 Location: Harlow, Essex, UK. Posts: 162	Re: Distortion on Grundig Concert Boy I have a Concert Boy which started to distort as the volume was increased and was cured by replacing the bridge rectifier. In fact the rectifier must have been faulty for a while to a lesser degree as after changing the rectifier I needed to reduce the Bass setting.