# Room EQ causing hiss



## jimbodude (Jul 26, 2011)

I've got some hiss coming from my Denon AVR-2807, and it's annoying. For a while, I thought my Bluetooth A2DP adapter had a really crummy DAC in it, but I've recently disproved that (I think) and now am focusing on the Room EQ. Maybe someone can give me a hint on what to look at next.

When I activate the Room EQ to any setting (Audyssey, Flat, Front, or Manual) and put the volume to about -10.0 (just over typical music listening volume for me), I get a very clearly audible hiss even with no audio playing. I get the same hiss on all inputs, even the ones that don't have anything connected. If I mute, the hiss goes away. If I deactivate Room EQ (Off setting), the hiss goes away at all volumes. I can also put the volume much higher with the EQ off - I guess Room EQ limits the volume knob for some reason...?

The one thing I have not checked is what the EQ for Manual is set for currently. I will try to test with flat (no adjustment) settings and see what that causes.

Do other people have hiss with the Denon Room EQ? Is this something specific to the 2807 vintage? Why does the output volume get limited when Room EQ is activated?


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## PassingInterest (Mar 29, 2009)

I think you should contact Denon for repairs. What you are describing is definitely not right. And no, the volume should not be limited by activating EQ.


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## jimbodude (Jul 26, 2011)

I figured that was screwy, which is why I suspected the A2DP's DAC for so long. I'm planning some equipment upgrades in the next few months, maybe time for a new AVR too...

Thanks for the confirmation.


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## AudiocRaver (Jun 6, 2012)

jimbodude said:


> The one thing I have not checked is what the EQ for Manual is set for currently. I will try to test with flat (no adjustment) settings and see what that causes.


Did you check those EQ settings? Could high gain in the higher frequency bands be a contributor? Does the noise go down with a flat setting?


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## jimbodude (Jul 26, 2011)

I meant to check last night, but I didn't get to it. Still, I don't see why there would be hiss when inputs that have nothing connected are selected...


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## jimbodude (Jul 26, 2011)

Alright, it turns out that my testing strategy was not completely correct, and my assessment of the issue was incorrect. I've now found that there are at least two sources of hiss. The EQ and the surround mode... Here are the settings that I've found. 

EQ Off, and direct or pure direct mode - - no hiss
EQ manual with flat (no adjustments) and direct mode - - some hiss at any high volume
EQ manual and any surround mode - - clearly audible hiss
EQ Off and any surround mode - - faint hiss at full volume

So my guess is that the digital circuitry in this receiver is at fault. I'm not sure if this is a design issue that is unrepairable, or if some interference is getting in there. Anyone ever seen this sort of thing?


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## Wayne A. Pflughaupt (Apr 13, 2006)

It’s common for digital processing to introduce noise, but I would think with a receiver in your price range it wouldn’t be so bad that you could hear it from the listening position. If it’s something that’s been apparent as long as you’ve had the receiver, and not something that recently appeared, then I’d say it’s just a poorly-designed piece of equipment.

However, highly-efficient speakers are known to highlight background noise problems. What speakers do you have? And your -10 dB volume setting, what percentage is it of the receiver’s full volume range? E.g., is -10 dB 50% between the minimal and maximum settings, or what?

Regards, 
Wayne


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## AudiocRaver (Jun 6, 2012)

jimbodude said:


> Alright, it turns out that my testing strategy was not completely correct, and my assessment of the issue was incorrect. I've now found that there are at least two sources of hiss. The EQ and the surround mode... Here are the settings that I've found.
> 
> EQ Off, and direct or pure direct mode - - no hiss
> EQ manual with flat (no adjustments) and direct mode - - some hiss at any high volume
> ...


Was working on pretty much the same response Wayne P posted, he beat me to it. Are you certain that the noise wasn't there before? Truly not intending to question your expertise. In a system with a lot of available gain, you might simply have not heard it until one day you crack up the knob volume knob and "hey, where did that come from?"

If turning on manual EQ set flat plus surround produces audible noise at the listener position without increasing the volume control, of course that is a major problem, one you most likely would have noticed if a design problem, so more probably it would be defective. OR... Turning on manual EQ set flat plus surround, then turning up the volume until noise is just audible at the listener position, how much gain do you apply? If 20 DB or more, then it is probably not a real problem, just something you have only noticed recently.

Again, not questioning your expertise, just stating that this has happened to many of us. One day we push a button, turn a knob, hear something new, exclaim "hey, where did that come from?" Sometimes it was there all along, we just never ran across it. Truly trying to be helpful, that's all.:T

AudiocRaver


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## jimbodude (Jul 26, 2011)

It is definitely possible that I just hadn't noticed it until I started listening to more music. Before getting this A2DP thing, this system was primarily for movies. I don't typically crank it as high for movies, and I have some projector fan noise directly above my head to distract me, which I obviously don't have when music is on. (projector is the next upgrade I was alluding to earlier) The motivation to open this thread was one of my friends, who doesn't have an ear for this sort of thing, noticed it and that caused me to look for a solution. 

The speakers I have are nothing terribly fancy - Mirage omni 250's with matching omnipolar center and surrounds, 7 channels.

The range on the receiver gain is -80 to about +30, depending on the surround mode and EQ settings. In the "worst" combination, the maximum is reduced to +10. -30 is about comfortable for TV, -20 for movies, -10 for music. Hiss is audible to me around -20 if the projector is off, no sound playing, and I'm listening for it. 

It sounds like the consensus matches my first thought - the receiver is either defective or designed poorly. Given the age of the thing, and the fact that I already have an HDMI switch because I have run out of inputs, it sounds like it might be time to consider an upgrade.

Thanks for the input, guys. I appreciate it.


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