Active Speakers hiss/hum

I have never used active monitors before. I just took delivery of a pair of Presonus Eris 8 active speakers. I connected them up to my DAW and ran some tracks through for  couple of hours. I really like the clarity of sound. However, in a break I thought I could hear a hum. I put my ear close to the speaker and sure enough there was some 100Hz hum. I thought it might be a hum loop so just to make sure I unplugged the cables from the speaker inputs. results, the hum is still there.  It is just audible from the listening postition. Not only that but it is the same on both speakers. I then put my ear close to the dome tweeter and I can clearly hear hiss. I already emailed Presonus to ask if this is normal or if the units are faulty. In the meantime I thought I would ask the assembled wisdom here if this is the norm for powered monitors?

Cheers

Ian

Hi Ian.
I have used several sets of Quested active speakers and never a hint of hum or hiss from them.
However, they are an order of magnitude more pricey I imagine than Presonus.

Powered up but not connected they certainly should not hum

The Gimmer

I just bought a pair of active EVE Audio speakers (SC208) and they are dead silent.
If you hear hum or hiss, there must be a design error.

A friend decided never to buy Presonus equipment again. He had one of their interfaces and the DESIGN errors in the build were astounding.
I have Yamaha HS8 active monitors and they are quiet.

There is a problem in KRK active speakers which causes low level hum. They use cheap crimp connectors on the wiring to the amp boards. The crimps don't work properly on the a.c. input wires, and a small amount of resistance builds up. This can be cured by soldering the crimps. In this mode, transformer feeding a bridge rectifier and large caps, the ripple current is very high, and crimps just don't work.
Not saying its your problem, but it could be.

Presonus replied to my ticket and simply offered to pay for there return for repair. Their RMA form applies to USA customers only. When I pointed this out they said I should contact my local distributor. I contacted the company I bought them from and they have agreed to take them back and give me a full refund. Talking on the phone to the guy who arranged the pick up he tried to tell me that all active speakers make some noise because the amplifier is on all the time. I told him I am an electronic engineer and I know just how much noise an amplifier should make. Fedex comes today to pick them up.

So, I would appreciate recommendations for replacements, powered or not but must have an 8 inch woofer.

Cheers

Ian

Lots of options, and very hard to advice when you can't hear for yourself.
I have heard that the JBL LSR2328P were good for price/quality, but there are so many options at that price range per speaker..., I guess first it's always better to choose a brand that is specialized in Speakers and not in all bunch of stuff, or lately in speaker business...
There is also those new Dynaudio DBM50 that has a slope for desktop use (might suite or not), and I think they were doing some kind of discount on them iirc, Maybe Mackie MR8 mk2 etc...

I demo'd the Eve audio Sc208 and Sc308, they were nice speakers, I preferred the Sc308, the 208 were too bright for my taste, but nice speakers nonetheless...

Very happy with my EVE Audio speakers SC208.
Silent as silent can be...
(8 Inch woofer!)

ruffrecords said:

Talking on the phone to the guy who arranged the pick up he tried to tell me that all active speakers make some noise because the amplifier is on all the time. I told him I am an electronic engineer and I know just how much noise an amplifier should make.

Click to expand...

You are tacking a matter that is often kept silent...
Neumann and Genelec produce figures for self-noise, but JBL, Presonus and KRK don't.
I have a pair of JBL4326 and surely there's some noise that I can hear if I set my ear at about 10" from the speaker.

You know that if one wants to make a system as silent as can be, they have to make the gain as low as practical. Unfortunately, a part of the purchase motivation is how loud the speaker sounds in the showroom, so the designers use more gain than necessary, which makes the circuitry's hiss audible.
Hum could be theoretically non-existent, but unfortunately facts do not agree. Many powered loudspeakers produce mechanically induced hum due to the mains xfmr vibrations, but there's always some hum in the audio path, that's inevitable.
There are so many other factors than self-noise in chosing a monitor system that I can only recommend that you arrange a comparative test with a dealer.
You may find that the most silent are not the best-sounding...

I also have a little noise on my Dynaudio's, need to get pretty close tough, but no hum nor hiss tough...

I did have a powered monitor start humming once, but just one of them.  Bad PSU cap, replaced, and all is well.  I think it gets hot in there (these were little monitors).

abbey road d enfer said:

There are so many other factors than self-noise in chosing a monitor system that I can only recommend that you arrange a comparative test with a dealer.
You may find that the most silent are not the best-sounding...

Click to expand...

I had come to the same conclusion. Next time I am in Norwich I plan to visit PMT and check out a few. As an aside, after packing the Presonus speakers, I put back my old Tannoy monitor golds and reconnected them the the Kenwood 75W hi-fi amp I got of eBay several years ago. I turned it on, set the levels to their normal settings and stuck my good ear right next to the speaker cone. I could hear the faintest of hiss and absolutely no hum.

Cheers

Ian

Ian,

Just as another datum point, I recently installed a studio in a place where the client's monitors hummed slightly. He'd never noticed them humming before.

When he took them home, they didn't hum. Then he tried plugging them in in different locations, and found that the mains waveform at his studio was causing the problem. -The transformer core was having an issue with the shape of the (full-online uninterruptible in this particular case) incoming power. -Switching to NON backed-up power immediately cured the issue.

This of course was ƒ (=60Hz) as opposed to 2ƒ (120Hz) so if you're experiencing 2ƒ noise, that would ordinarily mean I'd star looking at the pot-rectifier ripple, hoping that it's not board layout sensitivity issues...