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hiss from 8040b drivers

pcmedicfixit, modified 8 Years ago.

hiss from 8040b drivers

Youngling Posts: 1 Join Date: 1/10/14 Recent Posts
I recently purchased the 8040b monitors after listening to the 8040a and really enjoying the sound and clarity.

When I power the monitors and turn them ON (with nothing else plugged into them, only power, no audio XLR cables) I hear an equally loud hiss out of both of the monitors' tweeters, and a lower hiss out of the woofer.

This is not a humm that many people describe from the power supply, but rater a hiss from the speaker drivers themselves.

The hiss is equally loud from both monitors. Both monitors were purchased brand new.

My gain on the back is set to 0 on both. none of the jumper have been changed from stock.
Even with gain down to +6db the hiss is the same, and only a tad louder at -6db.

This hiss is not very loud but very audible at 3-4 feet of distance from the speakers in a quiet room.

Since I am hearing the same hiss from both (without anything else plugged into the monitors, no audio in) I am thinking that is an intrinsic hiss to the speakers.

I also hear the hiss when my audio in cables are connected, and I can hear it through very quiet music at 4 feet away.

The hiss just becomes annoying when there is no music being played, and the monitors are on.

Am I missing something? Anyway I can get rid of this hiss with different jumper selections? bad batch of speakers (I doubt it)?

Thanks in advance

jeff, modified 8 Years ago.

Re: hiss from 8040b drivers

Youngling Posts: 6 Join Date: 12/26/13 Recent Posts
I think it might be caused by the built in amplifiers. I know the B series has energy saving design. Maybe it's the curcit's problem.
ilkka-rissanen, modified 8 Years ago.

Re: hiss from 8040b drivers

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi Bob,

It is natural for all active speakers (or passive speakers which are driven with an amplifier) to have some amount of noise, typically described as hiss, coming from the drivers. Our rated noise level for 8040 is less than 10 dBA at 1 meter distance. In this respect Genelec monitors are among the very best you can find in the market. This amount of noise shouldn't be audible to a human ear even in a quiet room at more than 1-2 feet distance. If you can hear it at 4 feet distance, it would indicate that the noise level is higher than typical.

Is your listening room specifically designed to have extremely low background noise (NC rating? ... d_725.html) and/or do you self have an extremely good hearing ability?

I can assure that the energy saving ISS function does not cause any noise.
matthiola, modified 8 Years ago.

Re: hiss from 8040b drivers

Youngling Posts: 5 Join Date: 11/13/13 Recent Posts
I have the 8240 that have slight audible hiss after cold power up. The hiss gradually fades out after warming up for 10 - 15 minutes. I don't know if this is the same for the 8040. Maybe it's the digital circuitry. After warming up I can still hear some residual noise at 3-4 feet, but barely noticeable. It's comparable to the 8030, which I owned previously, and those were very quiet.
ilkka-rissanen, modified 8 Years ago.

Re: hiss from 8040b drivers

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts

I haven't experienced that the noise would be much different right after a "cold start" or after the speaker has warmed up. It is true that the noise is little bit higher on the 8240 and 8250 models due to digital signal processing.
wilpo, modified 8 Years ago.

Re: hiss from 8040b drivers

Youngling Posts: 1 Join Date: 3/24/09 Recent Posts
8240s and 8250s and other dsp models take a few minutes for the D to A circuits to come to operating temperature. It is normal for the hiss to become a bit less obvious over this time period.