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8351A Hum HELP

torojr, modified 5 Years ago.

8351A Hum HELP

Youngling Posts: 8 Join Date: 12/28/15 Recent Posts
Hi, my name is Antonio

I recently purchased a pair of 8351A. The first time I switched on, both monitors have this hum:

https://youtu.be/v49b6bDWNAM

I'm running them in stand alone mode. I already disconnect the XLR audio input from both monitors and switch them on and the hum is still there. The hum is not constant, it is fluctuating all the time in both monitors. Something that I noticed is that the hum of one monitor is synchronized with the other monitor's hum. Also I already changed power cords of both monitors. Should I be worried about? Is there something wrong with the speakers? This hum affect the monitors performance?

P.D. I also have other active speakers and none of them have this issue.

Regards
Antonio Avila
campus, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 12 Join Date: 9/19/14 Recent Posts
I am sorry I can not answer your question but since I believe that you own also Genelec 8050 I am curious to know how much the hum of 8351 is higher than that of 8050. For what I know a slightly higher hum for digital Genelec with respect to analogue is normal.
How 8351 sound with respect to 8050? Advantages and disadvantages of each one?
Best regards
manutal, modified 5 Years ago.

Re: 8351A Hum HELP

Jedi Knight Posts: 180 Join Date: 4/25/14 Recent Posts
Little more hum, I own them both. It doesnt bother me though. Used to pcs and such :) Background noice.. ^^
ilkka-rissanen, modified 5 Years ago.

Re: 8351A Hum HELP

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Hi, my name is Antonio

I recently purchased a pair of 8351A. The first time I switched on, both monitors have this hum:

https://youtu.be/v49b6bDWNAM

I'm running them in stand alone mode. I already disconnect the XLR audio input from both monitors and switch them on and the hum is still there. The hum is not constant, it is fluctuating all the time in both monitors. Something that I noticed is that the hum of one monitor is synchronized with the other monitor's hum. Also I already changed power cords of both monitors. Should I be worried about? Is there something wrong with the speakers? This hum affect the monitors performance?

P.D. I also have other active speakers and none of them have this issue.

Regards
Antonio Avila

Hi Antonio,

Thanks for you message. When you say "the hum of one monitor is synchronized with the other monitor's hum", what other monitor you mean?

In which country do you live and how is the mains electricity quality there? It sounds like there could be some varying DC offset in the mains electricity which then makes the transformer inside the monitor emit that fluctuating hum. It is nothing to be worried about though, it does not effect the sound quality by any means.
torojr, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 8 Join Date: 12/28/15 Recent Posts
I am sorry I can not answer your question but since I believe that you own also Genelec 8050 I am curious to know how much the hum of 8351 is higher than that of 8050. For what I know a slightly higher hum for digital Genelec with respect to analogue is normal.
How 8351 sound with respect to 8050? Advantages and disadvantages of each one?
Best regards


Hi campus sorry for the delay in my response. Yes, the hum is slightly higher in the 8351's than the 8050's, not that much, but at my listening position (around 140cm) I can slightly hear it. And answering your question, the 8351's are by far superior than the 8050's, also the 8050's sound incredible, but definitely the 8351's are in another league. One disadvantage that I found with the 8351's is that they clip pretty quickly with bass-heavy music at higher volume (around 79-80 dB SPL) and the 8050's don't, they can handle such pressure levels pretty well.

Regards
Antonio Avila
torojr, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 8 Join Date: 12/28/15 Recent Posts
Hi, my name is Antonio

I recently purchased a pair of 8351A. The first time I switched on, both monitors have this hum:

https://youtu.be/v49b6bDWNAM

I'm running them in stand alone mode. I already disconnect the XLR audio input from both monitors and switch them on and the hum is still there. The hum is not constant, it is fluctuating all the time in both monitors. Something that I noticed is that the hum of one monitor is synchronized with the other monitor's hum. Also I already changed power cords of both monitors. Should I be worried about? Is there something wrong with the speakers? This hum affect the monitors performance?

P.D. I also have other active speakers and none of them have this issue.

Regards
Antonio Avila

Hi Antonio,

Thanks for you message. When you say "the hum of one monitor is synchronized with the other monitor's hum", what other monitor you mean?

In which country do you live and how is the mains electricity quality there? It sounds like there could be some varying DC offset in the mains electricity which then makes the transformer inside the monitor emit that fluctuating hum. It is nothing to be worried about though, it does not effect the sound quality by any means.



Hi Ilkka, thank you for your response, I'm from Mexico City and I must say that the mains electricity quality here isn't the best. Answering to your question, I referred to the other 8351 speaker, What I wanted to say is that the hum of both monitors are fluctuating at the same time, but yes, for me it makes sense that this hum is because of the "varying DC offset in the mains electricity" like you said. In that case with a power conditioner it will be ok? or what do you recommend me for that?

Also, when I play heavy-bass music at considerable high volume the speakers starts to clip but the led still green, is this normal? I can hear that the LF drivers are having a bad moment because they start to sound kind of distort, like when you use an EQ and crank up the bass and starts to sound saturated. Is this a normal behavior or is it something wrong with the speakers?

Regards

Sorry form my english I'm not a native speaker. ;)
ilkka-rissanen, modified 5 Years ago.

Re: 8351A Hum HELP

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

Hi Ilkka, thank you for your response, I'm from Mexico City and I must say that the mains electricity quality here isn't the best. Answering to your question, I referred to the other 8351 speaker, What I wanted to say is that the hum of both monitors are fluctuating at the same time, but yes, for me it makes sense that this hum is because of the "varying DC offset in the mains electricity" like you said. In that case with a power conditioner it will be ok? or what do you recommend me for that?

Hi Antonio,

A power conditioner might help but I cannot promise that with 100% certainty. It would be best if you loan such device and test it first before buying.


Also, when I play heavy-bass music at considerable high volume the speakers starts to clip but the led still green, is this normal? I can hear that the LF drivers are having a bad moment because they start to sound kind of distort, like when you use an EQ and crank up the bass and starts to sound saturated. Is this a normal behavior or is it something wrong with the speakers?

That is normal behaviour and tells that you are trying to play them louder than what they are capable of. Should you require more bass output, I would recommend to get a subwoofer, for example our 7370A model, and use for example 80 to 100 Hz Hz crossover frequency. This will help the system to play much louder as the low frequencies are reproduced by the subwoofer.
torojr, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 8 Join Date: 12/28/15 Recent Posts
Oh I see, is it harmful for the speakers to play them louder than what they are capable of?
ilkka-rissanen, modified 5 Years ago.

Re: 8351A Hum HELP

Yoda Posts: 2564 Join Date: 3/23/09 Recent Posts
Oh I see, is it harmful for the speakers to play them louder than what they are capable of?

If the red clip LED is blinking from time to time, there is no problem but if it is being constanly lit, it means that the protection circuits have been activated and you should turn down the playback level.
campus, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 12 Join Date: 9/19/14 Recent Posts

A power conditioner might help but I cannot promise that with 100% certainty. It would be best if you loan such device and test it first before buying.

I was told that for Genelec 8050B the power supply PCB has been recently redesigned to include DC filter to the power supply to avoid the hum of the toroidal transformer. If the new Genelec 8351 has no DC filter I suppose that there can be problems with such a filter (maybe reliability over time?). Can you please explain something more on this. I have to make a decision if change the power supply PCB of 8050B or not. These infos can help also the owners of 8351 that have hum due to toroidal transformer (if there is a new PCB also for 8351). Thank you very much.
ilkka-rissanen, modified 5 Years ago.

Re: 8351A Hum HELP

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

All 8351 units have DC block filters.

For 8040B and 8050B this was added on September 2014, so all units made after that will have DC block filters.
campus, modified 5 Years ago.

Re: 8351A Hum HELP

Youngling Posts: 12 Join Date: 9/19/14 Recent Posts
Hi, my name is Antonio

I recently purchased a pair of 8351A. The first time I switched on, both monitors have this hum:

https://youtu.be/v49b6bDWNAM

I'm running them in stand alone mode. I already disconnect the XLR audio input from both monitors and switch them on and the hum is still there. The hum is not constant, it is fluctuating all the time in both monitors. Something that I noticed is that the hum of one monitor is synchronized with the other monitor's hum. Also I already changed power cords of both monitors. Should I be worried about? Is there something wrong with the speakers? This hum affect the monitors performance?

P.D. I also have other active speakers and none of them have this issue.

Regards
Antonio Avila

Hi Antonio,

Thanks for you message. When you say "the hum of one monitor is synchronized with the other monitor's hum", what other monitor you mean?

In which country do you live and how is the mains electricity quality there? It sounds like there could be some varying DC offset in the mains electricity which then makes the transformer inside the monitor emit that fluctuating hum. It is nothing to be worried about though, it does not effect the sound quality by any means.


Hi,
Even if all 8351 have the DC block filter they can still have the hum of the toroidal transformer due to DC?
Main reason for asking is that if I decide to change the power supply PCB of 8050B (with the new one that include the DC filter) I want to solve the problem definitely. Can the power supply PCB with DC filter have disadvantages with respect to the old one without DC filter (e.g. reliability since a condenser is filtering the main electricity)?
Thank you very much.
ilkka-rissanen, modified 5 Years ago.

Re: 8351A Hum HELP

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

Hi,
Even if all 8351 have the DC block filter they can still have the hum of the toroidal transformer due to DC?
Main reason for asking is that if I decide to change the power supply PCB of 8050B (with the new one that include the DC filter) I want to solve the problem definitely. Can the power supply PCB with DC filter have disadvantages with respect to the old one without DC filter (e.g. reliability since a condenser is filtering the main electricity)?
Thank you very much.

DC block filter will prevent any sort of hum related to DC offset in the mains voltage. There are no disadvantages.