Quad 303 fizzle/crackling on ESL 57

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06-Jun-2019 02:52 PM

Not Available

Posts: 1

Hi everyone,

When using a Quad 303 with my ESL 57, there are audible fizzling/crackling sounds coming from the treble panels of both speakers. These sounds get louder when I increase the volume on my passive preamp. But it is already there if no audio signal is sent. Then it is only audible with an ear close to the grill. When using a modern amp instead of the 303, the speakers play as they should, with no noise at all.

Is it possible that the cable I'm using to connect the preamp with the 303 is the cause? It's a 4 pin-din to two rca, and then I am using rca to xlr adapters to connect to the preamp. I had an electronics shop custom solder the cable. I gave them the schematic from the Quad 303 manual for reference. But still it might be possible that they made a mistake.

If not the cable, is there any other likely cause I could be looking at? I don't know what work has been done on my 303, and I haven't opened it up yet. All I can say is that there is no visible bulge on the blue capacitors.

Thank you in advance for your help.
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16-Jun-2019 03:56 PM

Generator

Generator

Posts: 2

I'd say you are hearing failing components. The capacitors in your unit are likely upwards of 40 years old. Some of those old transistors are also prone to get noisy. Do an upgrade and get back to us if the problem persists. The 303 is a very lovely and stable amp, by the way. I use one every day;-)

Regards

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18-Jun-2019 07:49 AM

EJP

EJP

Posts: 1605

If it increases with volume it is coming from the preamp, not the 303, and from before the volume control. If it's a 33 preamp I would change both transistors on the tape board. Use BC549.

EJP

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