Sibilance on Grundig Marlborough 3028 - UK Vintage Radio Repair and Restoration Discussion Forum

Roy London · 19th Dec 2009, 1:14 am

Newbie....

I have recently acquired a wonderful Grundig 3028, which sounds great.

Classical music sounds excellent, ie Radio 3, but speech is a little sibilant on S's etc...

Is there a little capacitor mod I can carry out to tame the sibilance frequencies, whatever they are, without ruining the music? Reduction of treble is too coarse to deal with this.

Any good info gratefully received.

Radio_Dave · 19th Dec 2009, 11:41 am

Hi Roy,

I can't remember my 3028 having such problems. I'm not a clever as some of the guys here, so let's hope others will come forward, but I 'believe' it could be an alignment issue. Does it sound better if you tune,slightly, off station?

David

YT2095UK · 19th Dec 2009, 11:48 am

I`v encountered that on a few sets if the I.F is slightly out, and all the "S"`s sound like "shhh".
as Dave said above, if it`s slightly off station it can do that as well.

jjl · 19th Dec 2009, 12:03 pm

This can happen when the 4uF electrolytic capactitor in the FM detector is faulty. I'd try replacing this first. If you do replace the capacitor, remember that the positive end goes to chassis.

John

Sideband · 19th Dec 2009, 4:02 pm

I don't know the set but if it uses a valve discriminator like an EABC80 or possibly an EAA91 (EB91) that is also worth a try. One of the diodes may be low causing an imbalance.

Rich.

Roy London · 21st Dec 2009, 10:48 am

Many thanks Gents

replies very much appreciated, thank you

It's not extreme, just more than other radios and some voices worse than others....noticeable, subtle.... mildly niggling...always there.....

I will try all suggestions, thank you...it does utilise an eabc80...I think I have one....

will report back on all suggestions.......

paulsherwin · 21st Dec 2009, 11:34 am

Reception problems can also cause sibilance in the absence of a receiver fault. London is generally an area of good signal strength, but it is plagued with multipath reception blackspots because of all the high steel framed buildings, and the many pirate stations interfere with reception.

Paul

PaulR · 21st Dec 2009, 6:41 pm

I had a very similar problem on a Bush VHF61. The tuning was drifting and even when tuned properly it still had excessive sibilance.

I replaced all the Hunts caps which cured the drifting. "Tweaking" the FM alignment cured the remaining sibilance.

19th Dec 2009, 1:14 am	#1
Roy London Retired Dormant Member Join Date: Dec 2009 Location: London Posts: 15	Sibilance on Grundig Marlborough 3028 Newbie.... I have recently acquired a wonderful Grundig 3028, which sounds great. Classical music sounds excellent, ie Radio 3, but speech is a little sibilant on S's etc... Is there a little capacitor mod I can carry out to tame the sibilance frequencies, whatever they are, without ruining the music? Reduction of treble is too coarse to deal with this. Any good info gratefully received.

19th Dec 2009, 11:41 am	#2
Radio_Dave Nonode Join Date: Jun 2004 Location: Norwich, Norfolk, UK. Posts: 2,543	Re: Sibilance on Grundig Marlborough 3028 Hi Roy, I can't remember my 3028 having such problems. I'm not a clever as some of the guys here, so let's hope others will come forward, but I 'believe' it could be an alignment issue. Does it sound better if you tune,slightly, off station? David

19th Dec 2009, 11:48 am	#3
YT2095UK Retired Dormant Member Join Date: Sep 2009 Posts: 487	Re: Sibilance on Grundig Marlborough 3028 I`v encountered that on a few sets if the I.F is slightly out, and all the "S"`s sound like "shhh". as Dave said above, if it`s slightly off station it can do that as well.

19th Dec 2009, 12:03 pm	#4
jjl Octode Join Date: Jan 2003 Location: Ware, Herts. UK. Posts: 1,082	Re: Sibilance on Grundig Marlborough 3028 This can happen when the 4uF electrolytic capactitor in the FM detector is faulty. I'd try replacing this first. If you do replace the capacitor, remember that the positive end goes to chassis. John

19th Dec 2009, 4:02 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,580	Re: Sibilance on Grundig Marlborough 3028 I don't know the set but if it uses a valve discriminator like an EABC80 or possibly an EAA91 (EB91) that is also worth a try. One of the diodes may be low causing an imbalance. Rich. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

21st Dec 2009, 10:48 am	#6
Roy London Retired Dormant Member Join Date: Dec 2009 Location: London Posts: 15	Re: Sibilance on Grundig Marlborough 3028 Many thanks Gents replies very much appreciated, thank you It's not extreme, just more than other radios and some voices worse than others....noticeable, subtle.... mildly niggling...always there..... I will try all suggestions, thank you...it does utilise an eabc80...I think I have one.... will report back on all suggestions.......

21st Dec 2009, 11:34 am	#7
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: Sibilance on Grundig Marlborough 3028 Reception problems can also cause sibilance in the absence of a receiver fault. London is generally an area of good signal strength, but it is plagued with multipath reception blackspots because of all the high steel framed buildings, and the many pirate stations interfere with reception. Paul

21st Dec 2009, 6:41 pm	#8
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,236	Re: Sibilance on Grundig Marlborough 3028 I had a very similar problem on a Bush VHF61. The tuning was drifting and even when tuned properly it still had excessive sibilance. I replaced all the Hunts caps which cured the drifting. "Tweaking" the FM alignment cured the remaining sibilance.