# Distortion from equalizer?



## Ovation123 (Mar 6, 2011)

Hi,

First post here (though I've read a number of threads in here, especially recently).

I have an Onix R-DES and I've recently had occasion to move a few bits of my gear and reconnect and re-calibrate everything. I ran the rather cumbersome procedure for using the R-DES and uploaded (after many hours of work) a satisfying EQ plot, briefly listened to some bass heavy music (the EQ dealt with the two major peaks I had (one at about 33 hz and one at around 68 hz) very well and the bass was much more clearly defined). It did its job. The next day, however, I noticed (during quiet passages in a movie with a delicate score--_Never Let Me Go_) some sort of distortion. It was not especially loud (the previous night's music had drowned it out) but it was troublesome. I tried a variety of sources (analogue and digital connections to the receiver--the receiver does an A/D/A on all analogue inputs, including MCH); I substituted cables from the chain of receiver--EQ--sub. I plugged the sub into a different electrical circuit. When I connect the sub directly to the receiver, the distortion disappears.

My question is, would the distortion more likely be a problem with the box (some sort of electrical interference--as I suspect/fear) or with my EQ settings? The sub is a Boston Acoustics PV900 (never let me down since I've had it--spring 2004), the receiver is an Integra DTR 6.4 and the interconnects are pretty run of the mill.

Any ideas?


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## koyaan (Mar 2, 2010)

I would think that since the distortion disappears when you plug the sub directly into your reciever, the EQ device must be introducing the distortion.I'd fiddel with the EQ some more in the range thats distorting .


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## Ovation123 (Mar 6, 2011)

I'm not sure how I would identify the range at which the distortion is occurring as it seems unrelated to the music that is playing during the distortion (it even occurs when no music is playing at all).


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## JohnM (Apr 11, 2006)

Do you really mean distortion (sounds are not reproduced as they should be) or noise (present even when there is no sound from the source)? If it is noise, some sort of ground loop problem is the most likely cause. If it is distortion, look at your EQ settings and make sure you do not have a lot of gain in any EQ filter.


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## Ovation123 (Mar 6, 2011)

JohnM said:


> Do you really mean distortion (sounds are not reproduced as they should be) or noise (present even when there is no sound from the source)? If it is noise, some sort of ground loop problem is the most likely cause. If it is distortion, look at your EQ settings and make sure you do not have a lot of gain in any EQ filter.


I think noise might be a better descriptor, as it does not require an active source to produce it. However, it sounds like a faint rumbling, not quite static-like. It is not a hum or a whine. As for the EQ filter settings, four of the five are -5 dB or lower and the other is a 0 dB at a narrow null point. I'm not an expert at EQing but I know enough not to try to defeat a null with an EQ boost.

I will try plugging the EQ into a different electrical circuit (it is the only device I did not plug into a new circuit).


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## Ovation123 (Mar 6, 2011)

I plugged into a different circuit. Tried different EQ settings (I can store four separate settings). The problem remains. I watched a movie with a fairly active soundtrack, including some moments of low frequency at high output and the EQ, when on, made it sound better (less of a "one note" bass, more distinction in various notes and sounds) and, with the visuals as a distraction, the low level "noise" (distortion or whatever it is) was easily ignored. I have at least established that an EQ improves the sound of the bass (good to know when I upgrade).

However, with music, the "noise" is much harder to ignore--particularly with classical music that includes some quiet passages. Too hard to ignore, really. And it is a pain to have to plug and unplug various cables just to have the EQ for movies (and really, only those with a brash soundtrack) and no EQ for music.

I guess I'll simply live without an EQ until such time as I upgrade my receiver (my short list includes the Anthem MRX series, Onkyo/Integra (I currently have an Integra and it has served me well) and Denon (had a Denon before my Integra and it also served me--later my brother-in-law--well) because they offer ARC or Audyssey XT32). It is not as though my bass response at the moment is atrocious (even knowing that I can improve it with EQ, I do not find it bad without EQ--and no one else in my house even notices).

If I come across an affordable BFD in the interim, perhaps I'll play around with that. However, at this stage, I think I prefer something a bit less cumbersome (my R-DES is rather cumbersome enough and from what I gather, the BFD would be equally, if not more, so).

This site does have a lot of wonderful information about EQs and subs--I have learned quite a bit from reading a number of threads in here.


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## JohnM (Apr 11, 2006)

If you read through the sticky thread about fixing BFD hum problems you'll find plenty of info on potential solutions for the kind of noise problem you are finding, there might be something in there worth trying.


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## Ovation123 (Mar 6, 2011)

JohnM said:


> If you read through the sticky thread about fixing BFD hum problems you'll find plenty of info on potential solutions for the kind of noise problem you are finding, there might be something in there worth trying.


Thank you. I will look at that thread. My scepticism lies mainly in the fact the noise is not the typical hum/whine that I've heard with ground loop problems in other circumstances. But I will try them out before giving up entirely.


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

Ovation123 said:


> However, with music, the "noise" is much harder to ignore--particularly with classical music that includes some quiet passages. Too hard to ignore, really. And it is a pain to have to plug and unplug various cables just to have the EQ for movies (and really, only those with a brash soundtrack) and no EQ for music.


You’ve already noted that the noise disappears when you take the Onix out of the signal chain. If you don’t get any noise like that when using the BFD, you can be assured that the Onix is defective.  

Regards,
Wayne


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## sparky77 (Feb 22, 2008)

I suspect the eq is definitely the problem, and would suspect low grade a/d-d/a conversion, or downright lack of bitrate processing, if it sounds like a 96kb mp3 compression artifact it's in the processing.


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## EarlK (Jan 1, 2010)

> I suspect the eq is definitely the problem, and would suspect low grade a/d-d/a conversion, or downright lack of bitrate processing, if it sounds like a 96kb mp3 compression artifact it's in the processing.



I would also suspect that the EQ is the problem / specifically from the OPs descriptions, the noise sounds like it's from low level quantization error ( due to insufficient dithering or noise shaping being applied in the AtoD conversion) .

FWIW, I've found older generation Behringer EQs to be particularly nasty in this regard when reacting to low-level signals ( specifically; DSP8000s & DSP8024s when their filters are really worked ) .

<> cheers


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