C26 Buzzing Issue

[Finnston]

Hi, I'm very new to audio stuff so please keep that in mind in your responses.

I have a C26 Preamp that buzzes (combination of a hiss and a hum) fairly loudly in both channels, and can be heard during music playback (especially with headphones). It happens on all inputs, even those that are disconnected. Bass, treble, balance, and loudness effect the buzz, but not volume.

I've done all the usual things like cleaning the contacts and tightening the RCA inputs and outputs, but to no avail.

Any idea on why this is happening?

 

[perryinva]

Both channels with the same noise is often 60Hz from the power supply and/or common grounds. Has it been recapped yet? Ground loops were common in that generation of equipment, and can be a bear to track down. Sometimes it is DC on the power line feeding the gear. When I owned my C28, many years ago, I had the same complaint, (and others) & sent it to Terry and it came back only slightly better. He noted “about as good as it’s going to get”. I moved to the C33 which was dead quiet. Later on (much later) I found that the hum was aggravated by the use of older design Powerline ethernet adapters on the same circuits in my old house in other equipment. The C28 was probably fine, just sensitive to that.

 

[SaturationPt]

if I remember the C26 it does not have its own headphone amp, so what you're hearing through the speakers (and headphones) would also be coming through the amplifier.
Have you eliminated the amplifier as the source / amplifier connections? Have you also tried all inputs to see if it is on all inputs?

 

[Finnston]

if I remember the C26 it does not have its own headphone amp, so what you're hearing through the speakers (and headphones) would also be coming through the amplifier.
Have you eliminated the amplifier as the source / amplifier connections? Have you also tried all inputs to see if it is on all inputs?

Yes, I was talking about the headphone output from the AMP, which definitely is not the problem. (Buzzing does not occur with preamp switched off)

 

[Finnston]

Both channels with the same noise is often 60Hz from the power supply and/or common grounds. Has it been recapped yet? Ground loops were common in that generation of equipment, and can be a bear to track down. Sometimes it is DC on the power line feeding the gear. When I owned my C28, many years ago, I had the same complaint, (and others) & sent it to Terry and it came back only slightly better. He noted “about as good as it’s going to get”. I moved to the C33 which was dead quiet. Later on (much later) I found that the hum was aggravated by the use of older design Powerline ethernet adapters on the same circuits in my old house in other equipment. The C28 was probably fine, just sensitive to that.

It has not been recapped. Really hoping this isn't an issue with my house circuitry, would absolutely suck to have to throw away or give away a C26

 

[geespot]

My C26 buzzed from a nearby wifi router and computer.

 

[perryinva]

Without a recap/service there isn’t a lot else to recommend. The preamp is full of 50 years old electrolytic capacitors, many of which are there to filter out AC from the circuitry. If you don’t want to service it yourself, or pay to have it serviced, then sell it and get something newer.

 

[SaturationPt]

If it's an electrolytic capacitor with high enough leakage to create a buzz, it's warning you that it's close to taking down anything from a fuse to a transformer, get it diagnosed.