Amplifier Buzz

[Tea24]

I am getting a buzz or hum from my Quad 606 Mk 2. Is this normal & if not what might be causing it? (NB this is not an earthing issue; there is no hum through the speakers. It is simply the amp itself; doesn't interfere with the enjoyment of the music)

Any help much appreciated!

Cheers

Julian

[Ali Tait]

Sounds like it could be the mains transformer has worked itself a little loose. If you're happy doing it,remove the cover and see if you can tighten it's fixing bolts.
It could also be caused by dc offset on your mains,you could check it if you have a multimeter. Set it to dc and measure at a socket. Only do this if you're happy doing it as this kind of thing is dangerous if you don't know what you are doing!

[Tea24]

I definitely do NOT know what I am doing so will not touch anything!:rolleyes:

[Ali Tait]

Well the next step is to find someone that does!

[Lodgesound]

Does the hum occur after the amplifier has been on a while ie. after it has warmed up?

If so then it could well be loose laminates in the transformer due to breakdown of the laquer. This is only curable by either re-potting the transformer or by replacement - I had to replace a transformer in a Quad 405 due to this.

Quad will have a transformer - they are around 100-130 pounds.

[Tea24]

Just switched on and it is totally silent at start up Stewart so you may well be right. If I want to have it done up should I go to Quad or try Dada electronics or Fidele audio and do the two latter do good upgrades?

[Ali Tait]

If it is an E/I transformer,loose laminates could be fixed with some long bolts through the fixing holes (assuming it has them) and tightening them up.

[Tea24]

Ali, I am grateful for your help, but I am not a DIYer; I wouldn't know what an E/I transformer was if one mugged me & I wouldn't have the skill or temerity to undo the case & fiddle!:scratch:

In the meantime does anyone havklnowledge about the two 'upgrade' firms & whether their upgrades are worth it; it seems to me that if I need a repair I can either send to Quad or take the opportunity of upgrading at the same time, if it is worth it.:)

[Lodgesound]

Hiya;

E/I is the core shape and being a Quad it may well be an E type - any competent repair facility should be able to change it - just a matter of getting the new one and soldering it in place.

The suggested repair is a good idea although to do it you would need to remove the transformer from the amplifier and from it's shielding case (which knowing Quad it will have round it). Quite tricky to drill as well if you don't have access to a pillar drill.

[Barry]

Ali, I am grateful for your help, but I am not a DIYer; I wouldn't know what an E/I transformer was if one mugged me & I wouldn't have the skill or temerity to undo the case & fiddle!:scratch:

In the meantime does anyone have knowledge about the two 'upgrade' firms & whether their upgrades are worth it; it seems to me that if I need a repair I can either send to Quad or take the opportunity of upgrading at the same time, if it is worth it.:)

I can speak from experience of Quad's excellent servicing and repair service.

At the same time I would trust Dada's upgrading service and have heard good reports of Net Audio's upgrades (some, but not all). Using Net Audio would have the advantage that being a UK company, shipping costs will be less than having to send the amp to Dada in Belgium.

I have no personal experience of either Dada or of Net Audio, as I have done my own mods and upgrades on my Quad gear.

Regards

[Ali Tait]

QUOTE=Tea24;163430]Ali, I am grateful for your help, but I am not a DIYer; I wouldn't know what an E/I
transformer was if one mugged me & I wouldn't have the skill or temerity to undo the case & fiddle!:scratch:

In the meantime does anyone havklnowledge about the two 'upgrade' firms & whether their upgrades are worth it; it seems to me that if I need a repair I can either send to Quad or take the opportunity of upgrading at the same time, if it is worth it.:)[/QUOTE]

Yes I know,you said,but if you can find someone local to have a look,you can tell them what's been said and they will know what to do. You can of course send the amp to Quad or one of the places that do mods. Depends how much you want to spend. If it is just a loose transformer,you would be paying a lot for something that is trivial to fix, but it's your money.

[Tea24]

Good thinking, Ali, except you were not to know that I am in southern France and don't know anybody near here with the requisite skills. Also, Barry, by the same token Dada is on this continent, but I have used Quads' repair service in the past for my 66 pre 7 CD player & it was very efficient. I just wondered whether anybody out there had had any dealings with Dada or Fidele Audio and whether their upgrades are worth it (would I hear the difference)? I bouhgt the amp on flaebay about 6 months ago to replace my 306 (which I have kept) and apart from the present very minor problem am very pleased with it. It is pretty mint. I moved it about yesterday to see if it looked easy to open & then found the technical manual on Google & decided it was beyond me, but for the moment it has stopped buzzing, so I am keeeping my fingers crossed, but one day it will have to have a service/upgrade. Are the upgrades worth it?

[Ali Tait]

I did note you were in France. If you just want the buzz fixed, I'd suggest a visit to a local hi-fi shop. They will probably know someone who can help.

[Barry]

Good thinking, Ali, except you were not to know that I am in southern France and don't know anybody near here with the requisite skills. Also, Barry, by the same token Dada is on this continent, but I have used Quads' repair service in the past for my 66 pre 7 CD player & it was very efficient. I just wondered whether anybody out there had had any dealings with Dada or Fidele Audio and whether their upgrades are worth it (would I hear the difference)? I bouhgt the amp on flaebay about 6 months ago to replace my 306 (which I have kept) and apart from the present very minor problem am very pleased with it. It is pretty mint. I moved it about yesterday to see if it looked easy to open & then found the technical manual on Google & decided it was beyond me, but for the moment it has stopped buzzing, so I am keeeping my fingers crossed, but one day it will have to have a service/upgrade. Are the upgrades worth it?

Hello Julian,

Sorry, I didn't spot you lived in France. Please ignore my comments concerning Net Audio.

If it were me, I would have a look at the Dada site and see what mods/upgrades they offer for the 606 and how much they charge for these. I believe they have a contact link on their web site. Why not contact them describing your system and seek their advice?

Regards

[Glen B]

It could also be caused by dc offset on your mains,you could check it if you have a multimeter. Set it to dc and measure at a socket.

One does not just stick a multimeter on the mains to check for DC. The AC first needs to be attenuated so that its does not overload the front end of the multimeter. A 100K resistor and 10uf non-polarised capacitor in series across the mains is enough to accomplish this. You then connect the meter probes across the cap and take the reading.

For such use, I've rigged up a little contraption I keep in my toolbox, consisting of a plug and cord with the resistor and cap soldered to the ends and heatshrinked. I've left just a little bit of the bare leads of the cap exposed, where I can attach alligator clips. :)