Right amp channel is muffled and hums.

[Goochtoucher]

Hi,

You guys have solved many problems of mine in the past so hopefully this will be no different.

My setup is:

2x Wharfedale Diamond 10.1 Bookshelf speakers powered by a Quad 303 Amp, my marantz nr1402 serves as a pre-amp. The sound comes from my PC through a Creative Reckon Fatality soundcard.

The problem:

Recently, when I plug both speakers into the amp, the right speaker sounds muffled when playing music, voices or anything really and as soon as you plug it in, there is a low pitched hum that comes from the speaker.

What I have tried:

Swapping the speaker cables for ones I know work, this did not solve anything.
Swapping the speakers around to check it was not that particular speaker, the sound quality was excellent on the left and muffled on the right, so both speakers work perfectly.

Additional Information:

Shortly before this problem occurred, the speakers were spitting and popping in an irritating manner, I believe this was just when the receiver was off and it was only through one channel. I cannot remember which but I would assume it was the same channel and linked with my current problem.

Any help would be greatly appreciated.

 

[ImcLoud]

Here is what I would check {sounds like you already did most of it}
before condemning the amp channel, I would
first swap speakers from left to right
then swap channels from my pre amp from left to right {swap the rcas}
if the same side makes the noise after swapping inputs and outputs it is most likely the amplifier has a bad channel... I had this happen and When I switched the rcas it switched sides, turned out it was a bad rca cable...

 

[markw]

Shortly before this problem occurred, the speakers were spitting and popping in an irritating manner, I believe this was just when the receiver was off and it was only through one channel.

Since speakers don't generate sounds or make noises of their own accord, there's someting wrong with that amp.

 

[Goochtoucher]

Okay I will swap the RCA cable around and if it turns out that the amp has a bad channel, which seems likely to me. Any suggestions as to how to fix it?

 

[Goochtoucher]

Hi guys, sorry for the slow reply, I fell down the stairs and was unable to move my neck for a couple days, can move around now and have just tried your suggestion. The RCA cable is actually an RCA cable to 3.5mm Jack as it is being plugged into my pc from the receiver and then another RCA cable but to the specific end reqiured for my Quad 303, this means I cannot simply switch them around.

Any suggestions?

I also ruled out my soundcard as the onboard audio also produces the same hum when that is used intstead.

I have only had the amp for a couple of months and it was working perfectly when I bought it second hand so I really don't want to have to replace it.

 

[ImcLoud]

Do you have an ipod or anything else with headphone jack to try, your amp has 2 rca's rite, you cant swap them around...

 

[markw]

You're gonna have to stretch a little here to pinpoint the problem

1) Like McCloud said,try another source. If that fixes it, you found the problem.

2) If the problem persists, switch right and left channels between the preamp output and the power amp input. If the problem switches sides, the preamp is the problem.

3) If the problem persists, physically switch right and left speakers*. If the problem switches sides, the power amp is the problem.

If either the preamp or power amp is the problem, you'll have to take it to a tech. There are no user servicable parts inside.

If nothing makes a difference, I'm out of ideas.

* If you grasp the concept of what we're doing here, you COULD just switch the speaker wires on the back of the amp.

 

[TLS Guy]

Hi guys, sorry for the slow reply, I fell down the stairs and was unable to move my neck for a couple days, can move around now and have just tried your suggestion. The RCA cable is actually an RCA cable to 3.5mm Jack as it is being plugged into my pc from the receiver and then another RCA cable but to the specific end reqiured for my Quad 303, this means I cannot simply switch them around.

Any suggestions?

I also ruled out my soundcard as the onboard audio also produces the same hum when that is used intstead.

I have only had the amp for a couple of months and it was working perfectly when I bought it second hand so I really don't want to have to replace it.

Does the amp hum, if you pull out the DIN connector to the 303?

If not then you have damaged the 4 pin DIN plug most likely. These are easily damaged.

If the Quad 303 has developed a problem, you don't need to replace it. Take it or send it to the Quad service department at Huntiingdon. Rob Fain and his team will have it up and running in no time for very reasonable service charges. While they have it, have them convert it from the nasty European DIN connector to RCA sockets. This is very easily done.

Unfortunately Peter Walker was persuaded on the 33/303 and early 405s to be a good European and go along with every lousy EEC edict.

He got over it though, abandoned the EEC regulators and went back to RCA, for the 34, 44, 606 and 909.

The sooner the EUSSR, is relegated to the dustbin of history the better. If they are not stopped soon, they will blow up the whole world economy and send is all to the poor house.

 

[Goochtoucher]

Tried swapping the input on my receiver, that produces the same problem, same side.
So it could be either the RCA>DIN cable itself or the actual DIN connector on the 404?
Here's hoping it is the cable, but just in case it isn't where do I send the Quad to? and do I have to e-mail the first? I assume I do. Anyone have the e-mail address?

 

[Goochtoucher]

Just checked out the cable, none of the pins are bent and it doesn't wobble or have trouble doing into the female connector, but the hum is also still produces without the input cable even attached. It still only does it out of one channel so I can safely assume it is the amp?
Probably the most annoying part to have break, but oh well. These things happen.

Any details on what to do, where to send it, who to contact and any rough costs would be great.

 

[TLS Guy]

Just checked out the cable, none of the pins are bent and it doesn't wobble or have trouble doing into the female connector, but the hum is also still produces without the input cable even attached. It still only does it out of one channel so I can safely assume it is the amp?
Probably the most annoying part to have break, but oh well. These things happen.

Any details on what to do, where to send it, who to contact and any rough costs would be great.

Yes, it's the amp.

Here is the Quad contact page.

The service manager is Robert Flain. He is one of the "old hands".

Rob Flain, IAG Group Service Manager for: Quad - AudioLab - Wharfedale - Mission - Castle

Address: IAG Service department, Unit 4, St Margaret’s Way, Stukeley Meadows Industrial Estate, Huntingdon, Cambridgeshire, PE29 6EB.

Tel number: + 44 (0)1480 452561

Fax number: +44 (0)1480 413403

I'm not going to publish his email on a public forum.

I would phone and see if you could talk to him.

As to charges, I can't tell you as I don't know what is the matter with it. The service charges at Quad have always had a reputation for being very reasonable. They will get it ready for the next forty years!

Don't forget to have them get rid of that 4 pin DIN connector and put on RCA plugs while they have. If you want they can also fit in IEC mains plug, and get rid of the NLA mains plug on the unit.

I remember you are on the UK. I would make a trip up there and take the unit to them personally. There are some fine old pubs there with good food, as an added bonus for making the trip.

If you are in the South East, take the M1 until it becomes the A14 and then head towards, Huntingdon a short way on the A 141. Take a right at the first roundabout, Stuckeley Road. Take the first left which is St. Margarets Way and you are there!

 

[Goochtoucher]

Yes, it's the amp.

Here is the Quad contact page.

The service manager is Robert Flain. He is one of the "old hands".

Rob Flain, IAG Group Service Manager for: Quad - AudioLab - Wharfedale - Mission - Castle

Address: IAG Service department, Unit 4, St Margaret’s Way, Stukeley Meadows Industrial Estate, Huntingdon, Cambridgeshire, PE29 6EB.

Tel number: + 44 (0)1480 452561

Fax number: +44 (0)1480 413403

I'm not going to publish his email on a public forum.

I would phone and see if you could talk to him.

As to charges, I can't tell you as I don't know what is the matter with it. The service charges at Quad have always had a reputation for being very reasonable. They will get it ready for the next forty years!

Don't forget to have them get rid of that 4 pin DIN connector and put on RCA plugs while they have. If you want they can also fit in IEC mains plug, and get rid of the NLA mains plug on the unit.

I remember you are on the UK. I would make a trip up there and take the unit to them personally. There are some fine old pubs there with good food, as an added bonus for making the trip.

If you are in the South East, take the M1 until it becomes the A14 and then head towards, Huntingdon a short way on the A 141. Take a right at the first roundabout, Stuckeley Road. Take the first left which is St. Margarets Way and you are there!

It feels like a shame I can only thank you once for that post, the most helpful post I have seen relating to anything anywhere on any forum in any corner of the internet. Thanks again. I will try find some time to make the drive at some point, if not, some lucky courier will have to do it for me.