Hello Everyone,
Today, I pulled out and powered up an old Hafler P1000 amplifier that I had stored in a closet for many years. When I powered it up I immediately noticed a faint humming noise. This noise is coming from the actual amplifier assembly. I can feel the chassis vibrate.
The audio signal is clean, meaning that there is no obvious or audible ground loop hum in the speakers.
It occurs to me that it may be good to replace the power supply filter caps,
Is that too simplistic of a response?
Can you share any insights or advice?
Thank you.
Today, I pulled out and powered up an old Hafler P1000 amplifier that I had stored in a closet for many years. When I powered it up I immediately noticed a faint humming noise. This noise is coming from the actual amplifier assembly. I can feel the chassis vibrate.
The audio signal is clean, meaning that there is no obvious or audible ground loop hum in the speakers.
It occurs to me that it may be good to replace the power supply filter caps,
Is that too simplistic of a response?
Can you share any insights or advice?
Thank you.
Possibly, but it would be best to check the ripple on the power supply with a scope.
Also tighten all the transformer mounting bolts.
Also tighten all the transformer mounting bolts.
Thanks for the reasoned advice. I have yet to open the chassis so I will start with a visual inspection and checking the transformer mount.
Thank you.
Thank you.
Probably not a toroid, but if it is, also make sure its mounting bolt is not forming a shorted turn.
Wow, thanks for the tip about the mounting bolts. I opened the chassis and everything looked ok. No bulging caps etc. Then I tightened the mounting bolts a bit and observed the vibration reduce as I did so. Not trusting my ears or good luck I decided to loosen the bolts a bit to confirm this was making a difference. When I loosened them a tiny bit the vibration symptom completely disappeared. I can see that the transformer is mounted on round-shaped rubber mounts that are beginning to show signs of old age. I guess I stumbled upon a sweet spot where the resonance is nullified so I am very happy to put the amp back into service.
I am glad I asked here before doing anything rash. 🙂
Thank you!
I am glad I asked here before doing anything rash. 🙂
Thank you!
Great, maybe you can replace the aging grommets, but only use real rubber ones. Vinyl won't work right.
Maybe a local hardware store will have some.
As you've found out, there's a reason why they used the grommets, instead of bolting it directly to the chassis.
Maybe a local hardware store will have some.
As you've found out, there's a reason why they used the grommets, instead of bolting it directly to the chassis.
I don’t know if it pertains to the ei type transformer in your Hafler but I know toroid transformers can buzz if there is some DC on your AC line. I’ve used a “dc blocker” circuit to fix noisy toroids not sure if it would help you though.