Quad 50E. - UK Vintage Radio Repair and Restoration Discussion Forum

Western 91 · 4th Jun 2020, 10:37 am

Hi all. I have rebuilt a pair of Quad 50e amplifiers they work great and no noise on either of them. I boxed the amplifiers up sent them to my friend. Now that he has received them he says there is a buzz on both amplifiers even without a load on them. I would be grateful if a member could help me with any tips to give him. I cannot go see my mate due to being too far from me. I look forward to any replies and thank you in advance.

Regards, Western 91.

GrimJosef · 4th Jun 2020, 12:27 pm

When you say there's no load, do you mean no speaker attached ? If so then the buzz has to be coming from something electromechanical (mains transformers often buzz like this). I'd be a bit surprised if both had developed this fault in transit. Is it possible his mains is 'different' from yours in some way, perhaps with DC on it as discussed here https://www.vintage-radio.net/forum/...d.php?t=121181 ?

Cheers,

GJ

Edward Huggins · 4th Jun 2020, 12:30 pm

I wonder if one, or more, of the 35+ year old Boards has fractured in transit?

4th Jun 2020, 2:05 pm

Is there anything connected to the input? An open circuit input will pick up anything.

barrymagrec · 4th Jun 2020, 2:57 pm

Are they fitted with the input transformers and if so are they close to a powerful mains field?

snowman_al · 4th Jun 2020, 3:43 pm

They all have output transformers, some have input transformers, but not all.
E/I transformers are far less prone to buzzing from DC on the mains than toroidals.
Do you mean there is a mechanical buzz from the amp or a buzz through the speakers?

4th Jun 2020, 10:37 am	#1
Western 91 Diode Join Date: Apr 2015 Location: Welwyn Garden City, Herts. UK. Posts: 8	Quad 50E. Hi all. I have rebuilt a pair of Quad 50e amplifiers they work great and no noise on either of them. I boxed the amplifiers up sent them to my friend. Now that he has received them he says there is a buzz on both amplifiers even without a load on them. I would be grateful if a member could help me with any tips to give him. I cannot go see my mate due to being too far from me. I look forward to any replies and thank you in advance. Regards, Western 91.

4th Jun 2020, 12:27 pm	#2
GrimJosef Dekatron Join Date: Sep 2007 Location: Oxfordshire, UK. Posts: 4,311	Re: Quad 50E. When you say there's no load, do you mean no speaker attached ? If so then the buzz has to be coming from something electromechanical (mains transformers often buzz like this). I'd be a bit surprised if both had developed this fault in transit. Is it possible his mains is 'different' from yours in some way, perhaps with DC on it as discussed here https://www.vintage-radio.net/forum/...d.php?t=121181 ? Cheers, GJ __________________ http://www.ampregen.com

4th Jun 2020, 12:30 pm	#3
Edward Huggins Dekatron Join Date: Sep 2015 Location: Southwold, Suffolk, UK. Posts: 8,338	Re: Quad 50E. I wonder if one, or more, of the 35+ year old Boards has fractured in transit? __________________ Edward.

4th Jun 2020, 2:05 pm	#4
Guest Guest Posts: n/a	Re: Quad 50E. Is there anything connected to the input? An open circuit input will pick up anything.

4th Jun 2020, 2:57 pm	#5
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,561	Re: Quad 50E. Are they fitted with the input transformers and if so are they close to a powerful mains field?

4th Jun 2020, 3:43 pm	#6
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: Quad 50E. They all have output transformers, some have input transformers, but not all. E/I transformers are far less prone to buzzing from DC on the mains than toroidals. Do you mean there is a mechanical buzz from the amp or a buzz through the speakers? __________________ Never Leave Well Enough Alone...