I purchased a used Drawmer DL441 listed in great condition - it wasn't. Several screws were missing from the faceplate and they McGyvered some brackets to the sides so it can be secured on a rack.

When I power the unit on, I hear an audible buzzing sound from the unit. The buzzing doesn't affect the signal of any of the four channels within the unit, but it's irritating considering I want my room to be as quiet as possible. When I remove the top of the chassis, the sound goes away. My best guess is the transformer inside is buzzing against the chassis. I've read other threads where the transformer is not seated correctly, but I can't find any screws to tighten it. Another said clamping down the unit on the side that buzzes but when I try it's still there.

Is it safe to use the unit without the top chassis if I have it rack-mounted? I can try to prop something between the top cover and the chassis to elevate it on the side of the transformer if that helps. I just wanted to know if it's common for gear to buzz like this and if it has ever interfered with recordings, or if I'm just freaking out.

Yes, relatively safe if it's located where hands and wires can't get involved. Dust will eventually be a problem.
Common? Not really, though some older stuff can do this if transformer mounting is loose or the laminations are no longer stuck together.

It will interfere with a recording made in the same room if the mic picks up enough acoustic buzz. But it may not. You'll know.

I have a lot of rack gear and many of them have mechanical transformer hum, just like your Drawmer. My gear is mostly from the 80s and early 90s and it is pretty common that windings become loose and cause hum/vibration in the transformers on older gear. It is pretty annoying when you record something quiet with a LDC, and can also drive you insane if you have OCD.

Leaving the lid off can in fact compromise the noise specifications of the unit as that steel lid is part of the screening of the audio circuits. But it depends on what's above. Putting the rack in place while looking at the noise amplified by 50dbs in your DAW (looking at an EQs spectrum analyzer) is a good way to detect if placement and removal of the lid ads any noise.

I've used this method when arranging my racks (to some degree) as some gear just don't like having a huge transformer in close proximity - lid or no lid.

I can hear the fan of my Bricasti. Not loud at all. And that’s the only outboard that I notice making any kind of sound.

Anything is possible. I recall once a long time ago recording with a punk band in this small "studio". The "gear" in this guys studio made more noise than the unshielded guitar cables. It had so much beer and pop spilt all over the rack, it looked like the floor of a dance club when the lights come on at 2am.

The Roland Chorus Echo makes enough noise to annoy me when it’s on in our control room. The fan on the 480L is barely audible. And if I’m smashing room mics with all buttons in I hear needles smacking on the Urei 1176’s.

Tell me that’s not the sound of victory and success !!
Wiggy

I've found over the years the main culprit for mechanical buzzing is USA-built gear that is allegedly 'multi-voltage' but in fact struggles with higher European voltages (220-240v) due to an inadequate power supply that works fine at 110v but cr*ps out at double that.

At the moment the main offender in may studio is a dbx160A, but I have previously owned pieces by Furman, Aphex and Symmetrix that has exhibited some annoying buzzing.

That said, I have currently had to return my GAP LA-2A under warranty as it has developed a loud power-supply buzzing that is simply at an unacceptable level in the studio.

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PS I own a Drawmer DL441 like the OP, and heaps of other Drawmer gear that works fine with very low levels of acoustic noise.

Rack pieces with loose E/I transformers get a torroid replacement. That stops transformer mechanical noise and supplies more current in a smaller space.

The Drawmer 441 uses a tiny pcb mounted power transformer. Those have failed here, mostly from excess heat. I replaced them with a small torroid power transformer from Mouser. Hum and buzz goes away.

yes its possible. Analog gear can be noisy. Recently iv been seeing people talk about their black lion audio bluey projecting weird sounds out of it, I forget what they said, but something like it was acting like its own speaker. Very weird, but many people said that theirs did in fact do that aswell.

Hello, have the same problem here, would you please give me the reference for the transformer you are currently using for your DL441? Do you use your dl with 220 v? Thanks a lot.?️?️?️??