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Post by Marvin on Jan 28, 2011 0:49:49 GMT -5
I have experienced distortion problems most notably with a few songs from original CDs or WAV files via my squeezebox Duet.
Emo has tested the UMC and found it to be fine (replaced it, in fact).
The problem happens with digital or analog inputs, but can be forced to happen with virtually any song if I boost the EMO-Q. It seems like the more processing I ask the UMC to do, the more distortion. If I boost 2 or 3 bands of EQ to the max, it distorts badly. OTOH, cutting the same bands to the bottom limit causes no distortion, even though boost or cut still requires processing, in my book.
So I conclude that it isn't the processing load, but rather the boosting that is too much to handle.
Has anyone else experienced this? Try it on another UMC or other pre/pro--same result for you?
Is it normal? I noticed fully boosting 3 EQ bands in windows media player causes similar distortion. Is this normal in digital EQ processing? I guess I'm used to the old school tone controls that simply changed the sound, but didn't cause distortion unless the speakers couldn't handle the boost.
If the UMC tolerates only minimal boost of EQ, then the versatility is limited. I am limited to cutting other bands to achieve the same EQ.
Any advice appreciated.
Marvin
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Post by paintedklown on Jan 28, 2011 0:56:17 GMT -5
Without actually hearing your system, my guess would be that you are boosting the offending frequencies to the point your speakers are unable to handle them...thus over driving them and causing your distortion. I would also try swapping cables, and ensure all of your connections are tight and clean. If everything sounds fine prior to adding the eq boost, then perhaps try subtractive eq instead. This is used a lot in the recording world and is a great way to avoid speaker damage or overload. Instead of boosting the frequencies that sound good, cut the frequencies that aren't as pleasant, allowing the other frequencies to shine through better in the mix...I hope that makes sense. ;D Good luck. -Dave  |
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Post by roadrunner on Jan 28, 2011 2:55:58 GMT -5
It sounds to me like Dave hit this one on the nose. You are asking the cone in the speaker to perform beyond its ability and it is distorting. It is also possible that if you are driving the amplifier near its maximum undistoted volume level when it encounters the 10 DB increase in the selected band that it forces the amp into distress. Are you playing at a high volume level?
What speakers are you using? What amplifiers are you using? How large is your room? More than likely you are just forcing your speaker's cone to bottom out by suddenly forcing it to respond to such a huge increase in output.
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Post by autocrat on Jan 28, 2011 4:48:22 GMT -5
My money's on digital clipping.
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Post by Mischief on Jan 28, 2011 9:38:57 GMT -5
I have found that adjusting the EQ settings will on occasion cause some funky distortion that requires turning the unit off and back on to clear up. I have no idea why it acts this way and when it happens it is very annoying when taking measurements.
The previous posts also have some valid suggestions.
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Post by jason1976 on Jan 28, 2011 9:46:40 GMT -5
I have/had the same problem. It is digital clipping. It doesn't matter where the volume is set, the UMC will clip the signal.
What solves it for me is not using Dolby Volume when I'm listening to music. Apparently there is too much boosting going on with EMOq and with DV boosting frequencies it winds up clipping the signal.
The DV settings are still messed up in my opinion. Low clips the signal more, but high clips the signal less.
But to answer your question, yes there can be too much boosting with a digital signal in general.
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Post by Nemesis.ie on Jan 28, 2011 10:10:55 GMT -5
If you are getting the "fuzzy" effect when using DV, you need to go into the settings and change the DV offset parameter (probably in the + direction) until it goes away.
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Post by jason1976 on Jan 28, 2011 10:40:54 GMT -5
Thanks Nemesis,
I have scanned the manual and been through the setup menu zillion times. Where are the DV offsets?
I have tried the input trim levels, but that didn't work either.
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Post by Nemesis.ie on Jan 28, 2011 11:01:37 GMT -5
I seem to recall it being on the parameter menu (which is on the first page when you hit the menu button) you need to scroll up to get their quickly as it is one of the last items.
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Post by Marvin on Jan 28, 2011 11:19:45 GMT -5
Thanks to all for your suggestions.
I almost always listen at moderate levels. To me, loud is 80-85 dB, but most of my listening is well below that.
It is not related to volume level. When it distorts, adjusting the volume level simply plays the distortion louder or softer, it does not change the amount of distortion.
I am using an XPA-5 amp with home built Modula MT speakers (7" 2 ways), but have also tested with Celestion Ditton 33 (10" 3ways) to ensure it is not the speakers. I am not over driving the speakers since the distortion is the same at very low volume levels.
I have tested the system with different cables between the UMC and XPA, no difference. Connecting the Squeezebox directly to the XPA eliminates the distortion completely, but of course the EQ feature and digital processing (the UMC) is then removed from the chain as well.
My ideal is to keep EQ to a minimum, so my original EQ settings were very moderate--initially set by EMO-Q and then tweaked to taste. I first started noticing slight distortion on a few songs, often on some solo piano chords, but not limited to a single CD or label. Then I found that the distortion was repeatable with any source material when aggravated and forced by boosting the EQ. Conversely, it was eliminated by turning EMO-Q off.
I tend to agree with autocrat that it is digital clipping. That is why I wonder if others can force it with their UMC--you only need to boost 2 or 3 bands in one of the front channels while it is playing to demonstrate the distortion. If every UMC does this, then I will accept it as normal (at least for the UMC). But if no one else can repeat it, then mine is not normal.
Granted, boosting three EQ bands to the top limit is extreme, but that is only for test purposes. Still, moderate boosting of the EQ (+3 or 4 dB across 7 or 8 bands) seems to have a cumulative affect. Under these conditions, the songs known to produce distortion are worse, and more songs that normally don't distort, do. More EQ boost produces more distortion. More EQ cut does not produce distortion.
I thought the fact that I can duplicate the problem on my computer with Windows Media Player demonstrates that it may be the nature of the digital audio beast, but WMP is just on a cheap sound card with cheap desk top speakers. My expectations are higher for "pure digital nirvana" ;D
Thanks for your time,
Marvin
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Post by Marvin on Jan 28, 2011 11:36:06 GMT -5
I have/had the same problem. It is digital clipping. It doesn't matter where the volume is set, the UMC will clip the signal. What solves it for me is not using Dolby Volume when I'm listening to music. Apparently there is too much boosting going on with EMOq and with DV boosting frequencies it winds up clipping the signal. The DV settings are still messed up in my opinion. Low clips the signal more, but high clips the signal less. But to answer your question, yes there can be too much boosting with a digital signal in general. Thanks, Jason. Apparently some of you were adding replies while I formulated my second post. My first experience with the distortion was before I ever experimented with Dolby Volume (purist/minimalist approach). During the troubleshooting process, I found that mild distortion went absolutely wild when DV was added to the mix. That is when it went back to EMO for a check up. Your comment about the nature of digital signal boosting helps to explain what is happening. If that is indeed a limitation of digital audio processing, a note in the manual would avert a lot of owner frustration, as well as needless service/shipping expense for EMO. I have learned to enjoy the DV feature (modeler only) for music or TV at low volume levels. Marv |
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Post by Marvin on Jan 28, 2011 11:50:43 GMT -5
If you are getting the "fuzzy" effect when using DV, you need to go into the settings and change the DV offset parameter (probably in the + direction) until it goes away. Nem, My understanding of DV offset is to compensate for extra efficient or inefficient speakers. My Modula MTs are less efficient than most. I wonder how much inefficient speakers affect the EQ distortion, if at all? At one time, Lonnie or Eric? also suggested that I try adjusting the DV offset in the + direction, which I tried. I don't think it did much with the distortion. Besides, the DV info I read said inefficient speaker compensation adjustment is in the - offset direction. I have since adjusted the offset so the volume level between DV off or on are similar. Marv |
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Post by DeepThought on Jan 28, 2011 12:02:55 GMT -5
Marvin, your experience *EXACTLY* mirrors mine. This is my#1 complaint about my UMC-1. I find EMO-Q to be essentially useless. I emailed Emotiva about it two weeks ago, no response yet...  If I leave EMO-Q to do what it wants, I get really nasty midrange distortion. As you described. It's especially apparent on alto female vocals; Diana Krall, Madeline Peyroux, Norah Jones, etc. It's also bad on my Miles Davis Kind of Blue SACD, so it's not a question of bad source. This is not with crazy adjustments. EMO-Q's desired curve looks appropriate for my room; +0 in bass, a +2 to +4 boost in the midrange, and a slight dip in highs. But this midrange hump is causing the distortion. If I turn off EMO-Q, the distortion disappears. If I adjust the levels down to where the distortion ceases, then I've basically zeroed out the EMO-Q curve. Ergo, it's mostly useless for me. I am absolutely convinced that the distortion is coming from the UMC's processing, and not on the analog side. The distortion is there no matter what the volume level. Barely audible to blaring, still there. Digital clipping sounds like a perfect description to me. I do not use Dolby Volume for music, so I know for sure that's off. I've rebooted & reset my UMC-1 at least a dozen times, and this problem doesn't go away. I have had a couple of occasions where I've been tinkering with settings and I get some weird distortion that's similar, though much more extreme, than this. That does disappear with an input or power cycle. But not this midrange distortion that the OP's talking about. I'm using Axiom M80V2 speakers driven by an Emotiva LPA-1 amp in a roughly 18x35 room. So power & speakers should not be an issue. At least, I've never heard anything like this with any other AVR's running Audyssey or MCACC room EQing. I just leave EMO-Q off. While I wish EMO-Q worked as advertised, I am happy with the SQ of my system with EMO-Q disabled. |
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Post by Nemesis.ie on Jan 28, 2011 13:25:51 GMT -5
If you are getting the "fuzzy" effect when using DV, you need to go into the settings and change the DV offset parameter (probably in the + direction) until it goes away. Nem, My understanding of DV offset is to compensate for extra efficient or inefficient speakers. My Modula MTs are less efficient than most. I wonder how much inefficient speakers affect the EQ distortion, if at all? At one time, Lonnie or Eric? also suggested that I try adjusting the DV offset in the + direction, which I tried. I don't think it did much with the distortion. Besides, the DV info I read said inefficient speaker compensation adjustment is in the - offset direction. I have since adjusted the offset so the volume level between DV off or on are similar. Marv Whatever way it is supposed to work, I I have found that if your DV is giving distortion, if you adjust the offset "live" it fixes it. I suspect what it is doing is bringing the modelled curve/boost back into a range that is clipping less with the given amps/speakers/internal levels. Anyway, worth a shot. Edit: Are you using the latest 05 firmware that fixed the display of "modeller only" etc. It seems to suffer less from this issue IME too. |
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Post by Marvin on Jan 28, 2011 14:28:27 GMT -5
Very well stated, DT. Marvin, your experience *EXACTLY* mirrors mine. This is my#1 complaint about my UMC-1. I find EMO-Q to be essentially useless. I emailed Emotiva about it two weeks ago, no response yet... If I leave EMO-Q to do what it wants, I get really nasty midrange distortion. As you described. It's especially apparent on alto female vocals; Diana Krall, Madeline Peyroux, Norah Jones, etc. It's also bad on my Miles Davis Kind of Blue SACD, so it's not a question of bad source. This is not with crazy adjustments. EMO-Q's desired curve looks appropriate for my room; +0 in bass, a +2 to +4 boost in the midrange, and a slight dip in highs. But this midrange hump is causing the distortion. If I turn off EMO-Q, the distortion disappears. If I adjust the levels down to where the distortion ceases, then I've basically zeroed out the EMO-Q curve. Ergo, it's mostly useless for me. This is my frustration, too. Part of the reason for buying the UMC was to address room modes, but this problem severely limits the feature. I am absolutely convinced that the distortion is coming from the UMC's processing, and not on the analog side. Connecting my SB Duet player directly to the XPA proves that. The distortion is there no matter what the volume level. Barely audible to blaring, still there. Digital clipping sounds like a perfect description to me. I do not use Dolby Volume for music, so I know for sure that's off. I've rebooted & reset my UMC-1 at least a dozen times, and this problem doesn't go away. I have had a couple of occasions where I've been tinkering with settings and I get some weird distortion that's similar, though much more extreme, than this. That does disappear with an input or power cycle. But not this midrange distortion that the OP's talking about. I have had that other terribly annoying distortion, too, on one or two occasions. That I can live with since it almost never happens. I'm using Axiom M80V2 speakers driven by an Emotiva LPA-1 amp in a roughly 18x35 room. So power & speakers should not be an issue. At least, I've never heard anything like this with any other AVR's running Audyssey or MCACC room EQing. If other brands of pre/pros don't act this way, then EMO techs have more work to do. "Digital nirvana" has not yet been attained.  I just leave EMO-Q off. While I wish EMO-Q worked as advertised, I am happy with the SQ of my system with EMO-Q disabled. I, too, can get by addressing room modes with xover settings. Full use of EMO q and DV would be nice features to enjoy, though. Marv |
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Post by Marvin on Jan 28, 2011 14:55:49 GMT -5
Edit: Are you using the latest 05 firmware that fixed the display of "modeller only" etc. It seems to suffer less from this issue IME too. My FW is 7.02.00.05 (installed by EMO on its last trip to hospital). Is there a "modeler only" problem, or are you just using the term to describe the FW version? I am aware that the "modeler only" feature was available only in more recent FW versions, but am not aware of any problem with it. |
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Post by firstchoiceaudio on Jan 28, 2011 16:01:07 GMT -5
There is distortion on mine also. My UMC is only a few months old and is the .05 firmware. I had .14 firmware before it and it was just as bad.
I dont pretend to be a tech expert, but my Onkyo 906 had no issue with +8 boosts in EQ & tone controls. No prepro Ive owned(Anthems, Krell, Bryston, Rotel) have had distortion issues either.
If it is digital distortion....would that mean a EQ should kick in after the signal has converted to analog? Why is it other equipment has no issues with using digital EQ.
This is extremely frustrating. The UMC would have top rate SQ if the distortion was ever completely gone. The distortion is always there IMO....but hard to hear at times when EQ is flat.
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Pauly
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Post by Pauly on Jan 28, 2011 16:28:09 GMT -5
Firstchoice, are you hearing distortion with analog as well? Like in stereo listening to music, or in direct mode?
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Post by jason1976 on Jan 28, 2011 16:49:09 GMT -5
Yep you guys are having the same issue I am. It seems like it is limited to PCM source material or analog signals that get converted to digital. I never have trouble with DD/DTS sources.
I had an old Sony TAE1000ESD preamp many moons ago that I had this issue with. The Sony had a digital signal compression/expansion adjustment that made it go away.
I wonder if a similar adjustment isn't set correctly in the factory settings for the UMC.
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jamrock
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Post by jamrock on Jan 28, 2011 17:39:36 GMT -5
I calibrated my UMC-1 manually. Based on my understanding of how inconsistent Emo-Q can be, I have no use for it until the beta testers can confirm that it is consistently on target.
However, My UMC-1 has developed only what I can called a high pitched hum (not the usual ground loop sound). I believe that I am able to identify where it began. When I hit speaker calibration, the white noise in the L/F channel comes on for a split second, pause, and re-start with that "hum" I've turned off the UMC-1 with the back switch, unplugged it from the HPC A/V 15, but nothing can correct it. This noise is independent of volume and only comes on when a source component is turned on. Some times it gets a bit softer then returns randomly. But, other than soft passages, I can't hear it from where I sit 12ft away. However, even if you select the tuner and turn the volume to off, you can hear it quite distinctly.
I sent an e-mail to technical support and I am awaiting the response. I did speak with Vincent earlier about it also, but he requested that I wait until .05 is officially released.
Since I have no intent to return the UMC-1, it is sort of o'k. But not knowing when .05 will be officially released, it is a bit disconcerting. Otherwise, at my usual listening level, I hear only the music and this thing really rocks.
jamrock
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