dbx 160x unit hum

[BillSimpkins]

There is no hum in the audio signal, just emanating from the box itself. The unit functions great. I have a lot of vintage gear and it is the only piece that has hum. Almost as loud as a fish tank pump. The plug is an ungrounded 2-prong. The unit is old (low serial number).

I've never noticed this before from other 160x's.

a) Is this "normal"?
b) What is it and how should I fix it?
c) Should I not use it until it's fixed (i.e. will the ruin the unit or be a fire hazzard)?

Thanks!

[ttown23]

Originally Posted by BillSimpkins

There is no hum in the audio signal, just emanating from the box itself. The unit functions great. I have a lot of vintage gear and it is the only piece that has hum. Almost as loud as a fish tank pump. The plug is an ungrounded 2-prong. The unit is old (low serial number).

I've never noticed this before from other 160x's.

a) Is this "normal"?
b) What is it and how should I fix it?
c) Should I not use it until it's fixed (i.e. will the ruin the unit or be a fire hazzard)?

Thanks!

I have two 160x's and they both hum a little. Often it is the transformer (and these have transformers), sometimes it's a ground issue. Nothing to be too worried about IMO.

[imixrecords]

mine make noise as well. a bit annoying when mixing.

[Th3_uN1Qu3]

Physical vibrations of the transformer being transmitted to the case. Not too hard to fix if you get a little creative. Put a rubber or sponge strip under the transformer and rubber washers on the screws holding it to the case and it should become significantly quieter.

[BillSimpkins]

Originally Posted by Th3_uN1Qu3

Physical vibrations of the transformer being transmitted to the case. Not too hard to fix if you get a little creative. Put a rubber or sponge strip under the transformer and rubber washers on the screws holding it to the case and it should become significantly quieter.

You ROCK!

[Jim Williams]

If it's really buzzy, you have a loose wrap in the power transformer that's smacking around at 60 hz. I would replace it as it won't get better.

This is a subject I've not brought up as I thought it may be taken as extremely picky ass techy crappola. Yea, try saying that 3 times fast.

My room is now silent. Every piece is quiet. No noise, no hiss. Nothing is printed to masters, everything is well under -100 dbu noise, including the analog console. That is a result of years of work and research. I'm not complaining. It's right where I want it to be.

What does drive me nuts now is since this is a very quiet room acoustically, I have noise problems from the transformers in all the analog gear. The HDR is a switcher so it's quiet. When I power up the racks and console, all I hear now are transformers all buzzing a tiny bit. Yes, it pisses me off now.

Most would never notice, but I do as I will shut off anything not being used just to lower that hum a bit more. The fans here are also silent. If I use a SSD, that's silent. Them damm power transformers get you thinking about doing crazy stuff like remotely powering everything from dedicated filtered DC power lines, but that's too much for me. Put stuff behing glass and you can't access easily the knobs.

Some stuff has torriod power transformers installed, but they also hum a bit too. My 18 amp linear power supplies for the small 24x4x2 Soundcraft console buzz a lot, maybe if I go to 24 amp supplies? That seems nuts too as that would run a large 40 input Trident 80B console and jack up my power bill some more.

Has anyone in audio ever delt with this problem before and how was it done?

[Radardoug]

One of the big problems with US transformers is they don't put enough metal in them. So they are close to saturation, with increased iron losses. And that means they buzz.
Also its worth buying transformers that are potted, as this binds all the lams together.
Try buying transformers from suppliers building for the 50 Hz market, they have more metal.
Anything by Eventide will have a crappy transformer!

[Jim Williams]

Most of my power transformers are large enough, I do over rate them so they don't run at over 50%. Some are potted, if fact, all of them are, that's how they are made. Some are enclosed. No difference, they buzz at 60 and 120 hz.

The only transformers here that don't buzz are the wall worts. Well, they still do, but you need to stick your ear on them to hear it.

[BillSimpkins]

OK. I took the top off and the buzz went away. I assume the top casing is amplifying any vibrations. I put foam in every which place, made sure the transformer wasn't touching the top casing etc..... still buzzes as soon as the top is back on. Good times.
I think I may try rubber washers where the transformer is screwed onto the case.

[BillSimpkins]

bump. see previous post.

[5.333V]

i work in theatres some.

and some lamps (500-2000W bulbs) tend to cause physical humings.

i recently heard that this can be eliminated when using dimmers that produce sine wave current instead of the more common pulse wave currents found in cheaper/older dimmers (which we find in almost any theatre).

could this be something that works with the psu´s mains transformers aswell? constructing a mains distributor of some kind which your whole studio can live on?

or maybe an easier approach... simple filter on the 110/220AC line to give a smoother hum atleast..?

just wild guessing here!

[iLCacciLLo]

Originally Posted by BillSimpkins

The plug is an ungrounded 2-prong. The unit is old (low serial number).

I had the same problem in mine, I replaced the stock transformer for a Toroid with 15VA , 2 x 15V . Problem solved, no more buzz.
The transformers that DBX used in these units were never any good, and the Transformer wattage was on the low side, it was always a weak point in the unit.

Another important thing is that my unit also came with a 2 prong power cord, which means that there's no Earth connection, shouldn't the Mains be grounded?

with the new units the DBX 160A the Earth connects to the chassis, that makes more sense than to have the unit not grounded.
Whats your thoughts on this?

Thanks