Noisy Quad 33/303 system

[surv1v0r]

I have a Quad 33 / 303 / FM3 system. For some time I have been aware that there are unwanted sounds from the 33/303. I suspected that they were due to an ageing 303 power amplifier. However, yesterday evening I visited a neighbour who happens also to have a Quad 33/303 based system taking my 33 pre-amp and 303 power amp with me to try and isolate the problem(s).

On the basis of some experimentation and swapping units in and out I now get the impression that the problem lies not with my 303 but with my 33. The problem certainly followed my 33 back and forth and was not apparent when using his 33.

Aside from an initial "thump" on switch-on, there is a definite whooshing or rushing sound when I switch on the 33. It sounds somewhat akin to rushing water or a waterfall. This lasts for maybe a couple of seconds and then dies away.

There are a greater and longer-lasting range of sounds when I switch off the 33. These include rapid "clicking" sounds which gradually fade over about five seconds. I don't get the same effects when using the other 33.

For what it is worth, I use a Sony CDP-790 CD Player which has a variable line-out. I have tried playing this directly through the 303 and I get no extraneous noise at all.

Clearly my 33 needs servicing but I am curious to know what components may be causing this?

Any help and/or advice would be greatly appreciated.

 

[ChrisNC]

I'll be watching to see if there are folks with interest/experience with Quad. That said, you might also try the folks over at dada electronics http://www.dadaelectronics.eu/ForumRetrieve.aspx?ForumID=317

 

[surv1v0r]

A bit of an update:

• It is definitely connected with the 33, not the 303 or the speakers.
  
• The problem only occurs on a single channel.
• I have removed and reseated all five boards - this hasn't changed anything
  
• No amount of playing with the Left & Right and "Mono" or the "Stereo" buttons makes any difference, it is always just one channel.
• Swapping the two internal Amplifier PCBs (12017) makes no difference. Looking at the circuit diagram I get the impression that the filter switches and volume control are all that come between these PCBs and the output to the 303?

Does any of this help?

edited: A further observation - the rapid "clicking" sounds which gradually fade over about five (to ten) seconds seem to come from both speakers.

 

[slimecity]

The 33 isnt known as a great preamp - the 303 is a bit of a better standard - but IMO both need a bit of work to get them sounding OK. Have the amps been recapped at all? If the sound happens on startup only my guess is that the ageing caps are charging up and maybe you are hearing this....not sure if this is a "thing" or not but a recap would defo be in order if these components havent had this yet. Has your neighbour modded/refreshed his amps at all do you know?

 

[surv1v0r]

The 33 isnt known as a great preamp - the 303 is a bit of a better standard - but IMO both need a bit of work to get them sounding OK. Have the amps been recapped at all? If the sound happens on startup only my guess is that the ageing caps are charging up and maybe you are hearing this....not sure if this is a "thing" or not but a recap would defo be in order if these components havent had this yet. Has your neighbour modded/refreshed his amps at all do you know?

Any advice on "a bit of work to get [the 33 & 303] sounding OK" would be greatly appreciated. Are the DaDa kits what you are referring to here or is there more that can be done? I have seen stuff from Richard Brice, Briarsfield and NetAudio some of which seems viable for me. Assembling an "Input selector and Volume control box" would be an idea except that I want to listen to Vinyl.

As to the rest, I will answer when I get back, I am catching up in an Internet Cafe at the moment.