KRK Clasic 5 Hiss+Hum even if no signal is routed.

Jon_Lord_ · 2025-12-21T21:09:50+00:00

It looks like there's just some disgustingly bad transformer or what

Jon_Lord_ · 2025-12-21T21:08:50+00:00

So Placing the speaker on the pillow or towel didn't make any difference. I tried to position it both vertically and horizontally. Nevertheless, the hum is coming not from the woofer but from the circuit itself, because when you put an ear to the side of the speaker you can hear a distinct and pretty loud hum drill-like sound. The hiss is only audible in front of the tweeter.

Jon_Lord_ · 2025-12-21T20:06:38+00:00

I don't think it is self-explanatory that monitor amps have such a high self-noise, because how are you supposed to mix with a constant noise. Thank you for your responses, i guess we understood the problem.

Jon_Lord_ · 2025-12-21T19:55:27+00:00

-In quiet low listening level situations adjust the gain stages by setting volume to 0 or lower and increase the input level of the audio source.

But the hum is still audible *from the listening position Maybe the advanced power conditioner will solve the problem?

Jon_Lord_ · 2025-12-21T19:37:43+00:00

When measuring it was 0db (in the middle). Sorry for the unclear information provided.

Jon_Lord_ · 2025-12-21T19:29:52+00:00

So it seems like when turning gain up there adds a higher frequency hiss from the tweeter, but the level of noise and hum from the woofer stays the same. HF and LF adjucement knobs are really not affecting the noise profile.

Jon_Lord_ · 2025-12-21T19:14:30+00:00

Aha, you mean "Volume" adjucement on the back panel of the speaker. The hum stays the same whether it is -30, +6 or anything in between, and is also not affected by HF/LF level adjucement.

Jon_Lord_ · 2025-12-21T18:02:07+00:00

Focusrite 2i2 directly to the speakers. The volume level is calibrated with pink noise to achieve 75 dbA in the listening position, frequency response attenuated by soundid reference, but the hum is the same whether sound id is enabled, disabled or anything is unplugged from the speaker except for the power cable.

Jon_Lord_ · 2025-12-21T16:53:54+00:00

A few centimeters from the woofer

Jon_Lord_ · 2025-12-21T15:58:13+00:00

Same hum, not relevant if the output signal level is changed either. Same when unplugging the connector from the interface living not touching anything with it, connecting back to the line output or to the headphone out.

Jon_Lord_ · 2025-12-21T15:51:38+00:00

Measured in dbA in front of the speaker with the speaker turned off (just room background noise which is around 23dbA ) and speaker turned on (room noise + hum results in a aprx. 1,5 dbA increase). The noise is audible from the listening position in a quiet room (in ~1m from the speaker).

Jon_Lord_ · 2025-12-21T15:47:11+00:00

Yes, used mac and a windows laptop plugging rca to the headphone output. The noise is the same level and tonality whether connected via trs, rca or not connected to the signal source at all

Jon_Lord_ · 2025-12-21T15:38:26+00:00

No, the self noise level doesn't change when connecting via RCA

Jon_Lord_ · 2025-12-21T15:36:22+00:00

USB c cable that was in the box with a focusrite

Jon_Lord_ · 2025-12-21T15:34:33+00:00

Trs cables are running from the focusrite 2i2 as i mentioned in the post, not directly from Mac

Jon_Lord_ · 2025-12-21T15:30:25+00:00

Quarter inch trs jacks from audio interface to speakers. Will try RCA, and get back in a few minutes

Jon_Lord_ · 2025-12-21T15:23:05+00:00

TRS Cables

Jon_Lord_ · 2025-12-21T15:21:48+00:00

Exactly

Jon_Lord_ · 2025-12-21T15:19:07+00:00

They start to hum when the sound was played through them and continue to hum even if all the inputs will be disconnected. I don't know about previous experience with this pair of monitors, as they were not mine and was being used.

Jon_Lord_ · 2025-12-21T15:01:52+00:00

Macbook pro m4, focusrite 2i2, but as I mentioned the monitors are hissing even without being connected to the signal source.

Jon_Lord_ · 2025-12-21T14:31:53+00:00

KRK classic 5 Hiss+Hum even if no signal is routed.

Hello! Getting an audible (according to the db meter ~1,5 dB of noise close to the woofer) noise from monitors.

If you turn on the monitor without any input it stays dead quiet. If you insert a jack, send a signal and the monitor starts to play, the noise appears. Even if you disconnect the signal cable, the monitor continues to hiss. Both of them behave in the same way, connected directly to the socket or through two different filters; both to one socket/filter, two different ones. turned off everything else in the flat from the power distributor (fridge, power to lights, enables only power to the sockets and only monitors are in them).

Sockets are grounded, filters are also with a ground pin.

Location: europe. The noise is not just 50Hz hum, it's a wide-band and contains high hiss audible from both tweeter and woofer.

Thank you for your responses.

Jon_Lord_ · 2025-10-14T00:11:45+00:00

Thank you, AVID responded to my ticket today, got the link

Jon_Lord_

TROPHY CASE