Slight buzz from MA230

[cspyon]

I just picked up MA230 from authorized McIntosh dealer in Maryland, ProTech. It was in great working condition, except for a loud audible buzz from the choke right behind the power transformer when powered on. The technician thoroughly checked it and identified the cause of the buzzing: the old four big can caps. So, he replaced them with the caps tailored to factory specs and a couple of resistors inside. Now, the buzz I used to hear was gone, but when I put my ears close to the unit, I still hear a very slight buzz. I'm not sure if it's a mechanical or transformer buzz. Out of 10 buzzing noise, I would say it's 1 or 2. Is this kind of slight buzz inevitable? Just curious.

 

[SaturationPt]

I have never owned an MA230, however:

Hum vs buzz. I have no way of quantifying how loud the sound is, so normal will be hard to determine from “slight” or “1 or 2” for me. Maybe someone else with a healthy MA230 can tell you if it should be absolutely silent. Normally, most equipment with 60Hz power and a transformer will make some sound if you listen closely enough, which is expected. With the power transformer potted they are usually quite quiet.

Your description of a “buzz” though wouldn’t seem normal to me. I consider a hum to be a soft sound without harshness, which is what I would expect to hear if I listen closely in a quiet room. A “buzz” however I consider to have harshness, much like the Wahl trimmer that a Barber would use, has a sharpness, a cracking to it, not normal. No McIntosh gear I’ve ever owned nor heard has ever had a sharpness to the sound that the PT makes when powered up, tube or solid-state.

Maybe this doesn’t make any sense, and hopefully that someone with lots of MA230 experience will show up.

 

[cspyon]

I have never owned an MA230, however:

Hum vs buzz. I have no way of quantifying how loud the sound is, so normal will be hard to determine from “slight” or “1 or 2” for me. Maybe someone else with a healthy MA230 can tell you if it should be absolutely silent. Normally, most equipment with 60Hz power and a transformer will make some sound if you listen closely enough, which is expected. With the power transformer potted they are usually quite quiet.

Your description of a “buzz” though wouldn’t seem normal to me. I consider a hum to be a soft sound without harshness, which is what I would expect to hear if I listen closely in a quiet room. A “buzz” however I consider to have harshness, much like the Wahl trimmer that a Barber would use, has a sharpness, a cracking to it, not normal. No McIntosh gear I’ve ever owned nor heard has ever had a sharpness to the sound that the PT makes when powered up, tube or solid-state.

Maybe this doesn’t make any sense, and hopefully that someone with lots of MA230 experience will show up.

Thanks for your kind explanation. As a novice in this field, I think I wrongly described that little audible noise as 'buzz' instead of 'hum', based on your explanation. It definitely is not what you described as 'harshness'. I hear it only when I put my ears close to the unit. This soft little noise comes from the unit itself, not from the speakers, so I thought it was not some like speaker hum), but a transformer buzz.

 

[SaturationPt]

There is no official hum or buzz definition, I’m just trying to find a way to understand what you hear, and from your description it is likely within the range of normal sounds or at least not a failing transformer, hopefully we’ll hear from other MA230 owners.

 

[cspyon]

There is no official hum or buzz definition, I’m just trying to find a way to understand what you hear, and from your description it is likely within the range of normal sounds or at least not a failing transformer, hopefully we’ll hear from other MA230 owners.

Thanks for your observation. It's been fully tested and all the failing caps and resistors replaced, so I don't worry. I asked because I was curious. Time for happy listening!