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B&K REF 50 Processor Noise?

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#1 of 17 OFFLINE   Anthony_K



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Posted December 26 2002 - 02:28 PM

I recently received my second B&K REF 50 (the first was defective - the volume control did not work). The volume control works fine on the new unit, however, the front 3 channels emit a high pitched noise. You can hear it from the front right and left channels when you place your ear to the tweeter. However, you can hear it from the center channel from several feet away. The center channel speaker has higher sensitivity than the other 2 channels. I called B&K today and they stated that this is not unusual and is the result of processor noise. I've never heard of this before and when I inquired further they represented that their units do not include mute circuits, unlike other manufacturers. The lack of mute circuitry makes the processor noise audible. Does this make sense? Can any other B&K REF 50 owners hear this processor noise from their speakers? The sound is somewhat annoying and I am considering returning the processor for a different brand/model. Thanks.

#2 of 17 OFFLINE   AustinKW


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Posted December 27 2002 - 01:49 AM

AK, Cranked to reference (0db), only my kids can hear any hi-freq noise from the tweeter. They tell me they can hear it to about 6" away. I can't hear a thing. FYI. Austin

#3 of 17 OFFLINE   Jerry Klawiter

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Posted December 27 2002 - 02:06 AM

This is a copy of my reply from AVS.
My Ref50 = Zero noise in both unbalanced and balanced modes.
It is as Quiet as can be, but so are my amps..
My front speakers are MirageOM-5 and the Mirage
OM-C2 Center
These speakers have 90-91db sensitivity.
I at one time prior to the B&K and the Ref30 had a Sony Ta-E9000es.
Now that unit had a noise floor. The B&K is dead silent..

#4 of 17 OFFLINE   Chip E

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Posted December 27 2002 - 03:34 AM

My Ref50, Ref200.5 combo is dead silent. I run balanced out. My speakers are PSB Stratus Silveri 's and are rated at 91 db sensitivity (typical listening room).
- Chip


#5 of 17 OFFLINE   Brian Fitterman

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Posted December 27 2002 - 07:02 AM

I had a similar issue with an older B&K 2000 (I think that was the number - first DD unit they made). I ended up going to a HK receiver. However it was due to the speakers being way to sensitive. I had Klipsch KLF 10's and the matching center. They amplified ANY noise what so ever. I put other speakers on the system and it was fine. They have 98db efficency I think. Not good for seperates that have any kind of noise. I ended up later dumping the Klispch and going wtih Paradigm Studio and then got the Ref 20 and Ref 30...they were fine. You had to put your ear withing a few inches to hear anything.
My Home Theater - Anthem AVM-30, Krell KAV-2250, Von Schweikert VR4 GenIII SE, Mits HDTV, Pioneer 59avi...

#6 of 17 OFFLINE   Todd_Petersen


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Posted December 28 2002 - 06:36 AM

I just recenlty got the B&K AVR-507 and after a couple days when i would put the unit in sleep mode my front left speaker would emit a loud wind type sound. It almost sounded like a wind tunnel or pink noise. Anyhow I called them and they told me that one of the mute circuits was bad and to swap the unit out for another one. They said that when the unit goes in sleep mode that alls it does is mute all the speakers. Well one of the circuits is bad so it is emitting this awful noise. I hope the new unit will be better.

#7 of 17 OFFLINE   Kirk Mango

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Posted December 29 2002 - 05:22 AM

Yes there is processor noise with B&K. I own the B&K Ref 30 with Mirage OM5 fronts and OmC2 center as well as 4 OMR surrounds. They all emit a slight tiking and hiss sound through the tweeter and at different levels. It is very low you have to be within 10 inches to hear it but it is there. If you listen closely enough you will hear some sound through midrange and woofer as well but because of the different hz ranges it is a different sound. It is also much harder to detect. I would assume that the Ref50 has the same sound. I was told by B&K that this was processor noise and that that is because they do not use muted circuitry here. They felt that this circuitery may effect the quality/character of source material when they are used unless they where to spend a great deal more money on something that would silence this and not effect sound quality. They also said to do this would put this componant into another price catagory. How true all this is I don not know. Just repeating what I was told. KM P.S. Should also point out that I heard the same sound coming from the Ref 30 at the dealer with different speakers other then Mirage. Ex. Vienna Acoustics. Same sound as my mirages, maybe at a slightly lower level. I have a 7.1 system and the sound cannot be heard from the listening position. Only when you move close to the speaker and from every every tweeter. Hear it loudest, if you can call turning your head sidways within a foot of the speakers tweeter loud, from my Left Front OM5 tweeters. P.s.s Also, the sound is NOT volume dependant. Whether the volume knob is set to odB or 96dB the slight ticking and hiss is the same.

#8 of 17 OFFLINE   Jerry St.Marie

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Posted December 30 2002 - 04:55 AM

I'm a little curious. Can this noise be heard with any active source material or only with an unactive input? If I can't hear it while listening to music or a DVD why should I care? Either my REF20 is totally silent or I spent to much time in an arti base camp in Nam.

#9 of 17 OFFLINE   Tim Menefee

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Posted December 30 2002 - 08:48 AM

Hello All, I have had my Ref 50 for about a month and noticed this hiss as well. I am using it in conjunction with an ref 200.5 amp. My speakers are B&W N804, HTM1 and SCM1 surrounds. I have noticed the hiss in all channels; I am listening in stereo mode now through Dish Network and can hear the noise through the idle center and surround channels. Also, when I turn the volume down on the active stero channels, I can hear the noise when I put my ear up to the tweeter. I cannot hear it from a distance. I am using the XLR balanced outs. I thought I had a grounding problem, but the ground checks out OK and I have a good ground indicator on the Monster powers strip. I thought when I switched to the balanced outs, the noise would dissappear, but it has not. Chip mentioned that his combo is totally silent, whch has me concerened there is something wrong with the systems that have noise.

#10 of 17 OFFLINE   Kirk Mango

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Posted December 30 2002 - 11:21 AM

OK, I have heard this processing noise with many different speaker set ups and the Ref 30. I am positive the noise is the same on the Ref50. It is likely that If you are not hearing it you are not close enough to the tweeter to hear it (almost on top of the tweeter with your ear) or the speaker the system is connected to is not sensitive enough to display this noise. This noise is not audible at any distance, say your listening position, from the speakers. It does not matter whether you have a source on, you are in stereo mode, 5.1, 6.1, 7.1, or anything else. If the power is on you will hear it out of every tweeter, but it is just into the audible range depending on your ears ability to pick it up. It is not heard during source material because it is so low in volume that any db at all will pretty much drowned it out. Again, repeating what B&K told me, is that they do not mute anything coming out so as to keep any source material true to form. That is there explanation. To get ride of this would not be cost effective at this price point. KM

#11 of 17 OFFLINE   Tim Menefee

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Posted December 30 2002 - 11:56 AM

Thanks for the input, Kirk...true, I have to get very close to the tweeter to hear this. I must have very good high frequency hearing, my neighbor had one of those high frequency oscillators that was supposed to chase away racoons, dogs and whatever critters that were lurking in her back yard...that thing almost drove me away, I had to ask her to shut it down.Posted Image Also, this noise is really not bothering me that much and I can live with it. Truth is, I just received all of this gear as an early Christmas present from my wife and I am really enjoying it. I always thought I had descent stereo gear until I got this stuff. What a difference, I have never enjoyed listening to music and watching movies at home so much. I also got an Elite DV-45A and Mitsubishi 65100 DLP wide screen. I am experiencing the low LFE problem on the DV-45A. I need to find a way to control the LFE when listening to SACD/DVD Audio and not affect the other sources. This is proving to be a problem...but that is another thread...

#12 of 17 OFFLINE   Jerry Klawiter

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Posted December 30 2002 - 12:14 PM

Well, I just removed the grills from my Mirage OM-5's and placed my ears right next to the tweeters of all my Mirage speakers, I even asked my kids to try this. We have ZERO noise from the Ref50 Mirages are OM-5 / OM-C2 / OM-R2 These are 90-91db speakers, I use these amps HK Citation 5.1 bridged @ 300wpc, B&K St2140, SS thx M3 mono block amps. I use a Panamax 1500 power center.

#13 of 17 OFFLINE   Anthony_K



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Posted December 30 2002 - 02:24 PM

I find it interesting how everybody's system appears to behave differently with regard to the high frequency noise. I just want to make it clear - the noise I referenced is not a hiss. It is a high frequency whine, for lack of a better description. I've had 2 preamps in this very system prior to the B&K and other than a little hiss, which is normal, they were silent. Actually, with regard to hiss, the B&K may be the quietest processor I've owned.

The high frequency noise varies by mode. It appears to be most noticeable in the DVD Audio mode. The frequency gets higher and appears louder in this mode. With my system, it is always noticeable from a distance in the center speaker - although it does change in frequency and apparent loudness as you change modes. In the rear channels, there are modes where you have to place your ear right on the tweeter to hear it and other modes where it is noticeable from up to 7 feet away. In the front right and left channels, you have to place your ear to the tweeter to hear it in any mode.

If you have to place your ear to the tweeter to hear a noise, I do not few it as a problem. However, I do have a problem when I can hear it from 7 feet away. Obviously when you playback a source at a high volume, the noise is masked. However, if you play a source back at a low volume or during quiet movie passages, you can hear the noise.

I have a thread (http://www.avsforum.....hreadid=205400)on the AVS forum that has garnered more activity. There is also a second thread (http://www.avsforum.....hreadid=206193) started by someone else.

#14 of 17 OFFLINE   Chu Gai

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Posted December 31 2002 - 02:58 AM

if it's as bad as you say, return it or perhaps take a look around your room to see if you've got anything on the lines that may be contributing...maybe switch to a different outlet? in any event, don't blow the chance to get your money back by waiting too long.

#15 of 17 OFFLINE   Kirk Mango

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Posted December 31 2002 - 05:29 AM

Jerry, The only difference in your system and mine that I can see is the amplifiers. Mine are also B&K like the preamp. Maybe that is why you are not getting any hiss. Is it possible that there is muting circuitry in your amps which does not allow this whine to pass? Just wondering. I have seen many systems with the B&K give off this processing noise, however, all of them also had B&K amps which only have muting when the system is powered down to sleep mode. Other then that anything that is present is passed through to the speakers. At least that is my understanding. Anthony, I agree with you. Many who describe the noise as a hiss are actually hearing the same noise you describe as a whine. I would also refer to the sound as more of a whine. I think that describes it much better. If you listen closely to the midrange and the woofer you will hear more of a hiss. Like light air passing through However, in these drivers it is very very hard to hear. You have to be right on top of the speaker and in a silent room. Any ambient noise will drowned it out. I only tested this because B&K told me that this processor noise will be heard there too, just at an extremely low level and if your hearing is not good you will not pick it up. Also, if you listen closely enough and hard enough without any ambient noise you can hear a very very slight clicking along with this whine of processor noise. Again, B&K explained to me that this was all part of the processor noise due to them making the decision to not mute it out. Also, I have not really listened to this noise in different modes like Stereo, DvD, etc. But have heard it in in the different options of speaker configuration. I also notice it louder in some speakers then others. My left front OM4 is the lowdest can hear it while just walking by the speaker with nothing playing. My back surrounds are the toughest to hear it out of but it is there. You may have done more testing with regard to this processor noise then I have. When I first got my equipment, this was a concern. AFter B&K's explanation, which seemed plausible, I just never really went any farther then this. KM

#16 of 17 OFFLINE   Michael Mohrmann

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Posted January 02 2003 - 03:07 PM

Someone may have stumbled upon the reason why the whine occurs in the Ref50 and a possible solution. Check the following link on HTT for the details:



#17 of 17 OFFLINE   SteveHerrala



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Posted January 07 2003 - 09:58 PM

Hello All. I am the dealer that sold Anthony the B&K unit. I also wote up something quick at AVS. The "Whine" sound is nothing new. It was present on the REF20, 30 , and 50. In the absence of the mute circuitry which B&K refuses to use (because of added cost and degraded signal path) you will hear this noise w/o volume. I applaud there decision to avoid this circuitry and cost. Every processor has this digital noise but when you have a mute circuit or play a music/movies, the signal drowns out the noise (hence the term SN ratio). Some people are sensitive to this and cannot over look it and they have a right to return it. I have sold about 50 REF 50's now and Anthony is the only one who finds it annoying. Another mentioned they heard it but was wondering if it was normal. Over the past 3 generations, the topic has come up a few times. the only thing that comes up more is "my unit is running hot, is this normal"? By the way, the answer is yes. B&K will never win an Energy Star rating!! This does not make Anothony wrong that he is sensitive to it. I am positive that when I check this specific unit out and take a listen, it will sound like every other B&K REF 20, 30, and 50 that was made. If you have a REF 50, trust me this digital noise is there but it does not bother you. I have heard some systems where I have to put my ear to the speakers in order to hear it and others where I could hear it from 3 feet away (albeit I need to concentrate to hear it). For the record, I can hear it from 3 feet away on my system (Sim titan amp) and it does not bother me at all. Anthony will be getting his Integra from me and he will be happy. That is all that counts. I had one customer who returned a REF30 a couple years back becuase it drove him nuts. I had to put my ear 6" away to hear it but that drove him crazy! I would not define this as a problem. B&K sold a couple thousand of these last month while other prepro vendors sold 20-100 in a month. Hence, B&K understands how to design and how to make an exceptional value/high performance product. Thereby by out performing others that cost a lot more (hence there 15x sales increase over the past 4 years while others went down). I carry several of these other prepro brands and still recommend the REF50 in many cases. If you are considering a REF50 and this thread scares you away you will be passing up on one of the best prepros on the market independent of price. Since they heard these "complaints" on the REF20, and 30 and sales have sored over the past few years, they are not too worried about it. Neither should you. I don't check this site all that often so if you have a question or comment, email me off of my personal account at sales@soundvideo.com. Email me if I can help, even if you bought it somewhere else. Steve (Owner) of Sound Video

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