UMC-1 Analog Audio "NOISE" Issue (am I the first?)

[dmillerc5]

LATEST TEST UPDATE (01/31/10): I now am running an APC J15BLK line conditioner, retested previous tests now including PS3 blu-ray (dolby 5.1, etc.) decoded in PS3 PCM to UMC-1 via HDMI. I still have the same "hiss" as heard in all previous tests.
I have tried two pair of speakers, different RCA cables, different speaker cables, different analog sources. In all tests, the same level of "hiss" is coming out of the UMC-1 (with volume set to 0.0). Hiss is constant as volume is increased.

I'll hopefully be able to reach/talk to someone at Emotiva tomorrow or soon after to see how to resolve.

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UPDATE: My experience with noise/hiss has turned out to be with both analog and digital sources.
I will be calling emotiva Monday to discuss via phone. Perhaps the 1st firmware update will resolve, maybe not. Hope I didn't waste too much of everyone's time. thx.

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Greetings, I'm afraid I have lost track of all reported issues or concerns on this forum to date pending the first firmware update release. I know we all are hopeful the firmware update resolves most of the issues which have surfaced so far.
However, I have not seen any report of what I am experiencing (Analog Audio NOISE) - but I may have missed some posts. Please chime in if you have had similar issues so I know I am not alone.

Net summary: I have a significant and audible "hiss" in ALL Analog Audio input channels of the UMC-1 (Analog 1, 2, 3, 4 and EXT 7.1CH)

I've kept my testing basic and simple to try and eliminate other potential causes for the noise.
Note: My issue is ONLY for analog audio. If you are not interested in analog audio, you can skip reading the rest of this post.


My Equipment for this test:

• UMC-1
  
• XPA-2
  
• Klipsch LaScala speakers (104DB 1watt/1meter)
  
• Denon DCD-2560 CD player; using analog audio line-level out
  

Testing the UMC-1:
1.1) UMC-1 main L, R OUTS connected to the XPA-2 inputs via RCA cables. These are the ONLY connections to the UMC-1.
Nothing else is connected to the UMC-1. No inputs, no other outputs.
1.2) UMC-1 default settings are used; no EQ, main front speakers set to 0.0DB.
1.3) with UMC-1 powered on, I went to the audio input source selection (menu: Setup -> Input Setup -> Aux 3 -> Audio).
1.4) Then, as each analog channel input (Analog 1 thru Analog 4) is selected, a significant audible "hiss" is heard for approximately 2 seconds. This is with the volume set to 0.0. IF, the volume is changed (i.e. 0.0 to 0.5) during these first 2 seconds, the "hiss" is immediately stopped.
When selecting the "EXT 7.1CH" audio channel input, the same "hiss" is heard but will NOT stop.
Again, the volume is set to 0.0.
Keep in mind, I have no input device connected to the UMC-1 at this point.

Adding CD Player as an audio analog input device:
2.1) connected CD player via analog audio line-level OUT to the Aux3 analog input on the UMC-1
2.2) When the analog channel input (i.e. Analog 3) is selected, the same "hiss" is heard (as in # 1.4 above) but will NOT stop. As I play any music track, the "hiss" is constant and louder than music soft passages.
2.3) The above test results are the same when connecting the CD analog audio output to any of the UMC-1 analog audio input channels. I have a constant "hiss" using any of the four analog inputs on the UMC-1.
This is an issue as I would expect no audible sound when my input device is not playing.
I hope I am not alone with this issue and that this is being worked on by Dan/Lonnie & team.
Can someone please confirm they have had this same problem?!?

Note: the "hiss" (as mentioned above) is heard using both "stereo" and "direct" modes


3.1) For anyone questioning the analog signal quality from my DCD-2560, a sound test running the CD's analog audio line-level OUTs DIRECTLY to the speaker input terminals (that's right, CD line-level direct to speaker - using no preamp, no prepro) yields dead silence, as expected. Playing music tracks during this test were crystal clear with zero sound/noise with the CD player stopped, paused or between tracks. My CD analog audio output is clean.

4.1) Another issue experienced is the UMC-1 is producing a click/pop noise between every music track on the CD. Meaning, where the dead space should be between music tracks, the UMC-1 is causing "noise'. Again, in test # 3.1 above (CD direct to speaker - no UMC-1 or preamp), I have dead silence between music tracks.

one final note: due to the efficiency/sensitivity of my speakers, the "hiss" may be far more pronounced than typical. I would like to hear from others running Khorns or LaScalas. Nevertheless, I expect no "noise" from the UMC-1 which is louder than my music.

Thanks.

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Additional comments from my post this morning (for reference):
« Reply #5 Today at 8:53am »

Thanks for the comments so far.

jvgillow - good point on my 3.1 test, thx. My thought there was that my CD player could be ruled out. I believe you concur.

Also, I have tried two different pair of RCA cables from the CD player.

I also have the same constant "hiss" from running an iPOD to any analog audio input channel with yet different set of RCA cables.

My third audio source test was my PC/sound card. (a different set of different RCA cables); same constant "hiss".

One additional observation, I hear this same "hiss" immediately upon powering up the UMC-1. It doesn't last but a second or two, then pops/clicks, and then goes silent. (volume is 0.0).

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« Reply #8 Today at 10:12am »

thx, I am thinking along these lines as well.

I just carried up one of my polk RTi-10s (89db sensitivity) from downstairs to run the same tests. All hiss, as previously mentioned, is still present, although at a much lower level. I may not have even noticed it had I not been running my klipsch.

So, maybe a UMC-1 + XPA2 + LaScalas combo will not be a good one for me. I am seriously getting bummed now -- As I'm currently searching for a 3rd LaScala for my center and already have Heresy's for side surrounds and an XPA-5 on order.

Now, can others verify constant you have "hiss" coming from your tweeters (listening at a VERY close level to your speakers) for analog audio?

I would like other validations that my UMC-1 is in deed operating correctly (of course, if so, this noise will NOT work in my setup unfortunately).

[jahays32]

I have mp laptop hooked up to aux 3 and have no hiss.

[moe]

I just set my umc to ext 7.1,no hiss,I'm talkin' none,on 7's that's saying something.I had set my volume to 40,then I turned the volume to 0,still no hiss.Great news for me,hope that helps.

[jvgillow]

Test 3.1 isn't particularly valid because you aren't amplifying the CD line out at all. Even an awful $20 CD player would seem quiet if it's not amplified in any way.

The hiss is definitely not originating with your CD player unless it varies as you turn the volume knob on the UMC-1. If the hiss remains at constant volume no matter what, it is coming from the preamp.

[Deleted]

have you tried changing the rca cables ? Just curious because the Emo amps at times are very sensitive to certain cables.

[dmillerc5]

Thanks for the comments so far.

jvgillow - good point on my 3.1 test, thx. My thought there was that my CD player could be ruled out. I believe you concur.

Also, I have tried two different pair of RCA cables from the CD player.

I also have the same constant "hiss" from running an iPOD to any analog audio input channel with yet different set of RCA cables.

My third audio source test was my PC/sound card. (a different set of different RCA cables); same constant "hiss".

One additional observation, I hear this same "hiss" immediately upon powering up the UMC-1. It doesn't last but a second or two, then pops/clicks, and then goes silent. (volume is 0.0).

[Deleted]

then it sounds like you might have a defective unit.

[jvgillow]

Back when I had the LMC-1, I noticed some similar behavior to what you are getting with the UMC-1. I had av123 X-SLS speakers with moderate sensitivity, but the LMC-1 had a bit of hiss whenever the output was active. Not annoyingly loud, but if you got within a couple feet of the tweeters it could be heard. The unit had a self-muting feature so that if a digital input was selected, it would not start hissing until it detected an incoming signal. A few seconds after it lost digital signal lock (from powering off the source device), the hiss would disappear again.

I was able to work around the hiss because my external amps had adjustable gain. I simply lowered the gain on all of them from 100% to about 60% and then adjusted the master LMC-1 volume to compensate. With the Emotiva UPA/XPA amps you do not have the ability to adjust gain.

One of the consequences of having a preamp capable of 7V output is that the SNR is typically measured based on the full preamp output level. Most people will never get close to that 7V number since typical consumer amps only require 0.7V - 1V to achieve maximum power output. The UMC-1 manual does not appear to have a published SNR number. It does have this note though: "If you have very high efficiency speakers, these may tend to reveal noises which other speakers do not."

[dmillerc5]

Jan 30, 2010 11:00:50 GMT -5 jvgillow said:

Back when I had the LMC-1, I noticed some similar behavior to what you are getting with the UMC-1. I had av123 X-SLS speakers with moderate sensitivity, but the LMC-1 had a bit of hiss whenever the output was active. Not annoyingly loud, but if you got within a couple feet of the tweeters it could be heard. The unit had a self-muting feature so that if a digital input was selected, it would not start hissing until it detected an incoming signal. A few seconds after it lost digital signal lock (from powering off the source device), the hiss would disappear again.

I was able to work around the hiss because my external amps had adjustable gain. I simply lowered the gain on all of them from 100% to about 60% and then adjusted the master LMC-1 volume to compensate. With the Emotiva UPA/XPA amps you do not have the ability to adjust gain.

One of the consequences of having a preamp capable of 7V output is that the SNR is typically measured based on the full preamp output level. Most people will never get close to that 7V number since typical consumer amps only require 0.7V - 1V to achieve maximum power output. The UMC-1 manual does not appear to have a published SNR number. It does have this note though: "If you have very high efficiency speakers, these may tend to reveal noises which other speakers do not."

thx, I am thinking along these lines as well.

I just carried up one of my polk RTi-10s (89db sensitivity) from downstairs to run the same tests. All hiss, as previously mentioned, is still present, although at a much lower level. I may not have even noticed it had I not been running my klipsch.

So, maybe a UMC-1 + XPA2 + LaScalas combo will not be a good one for me. I am seriously getting bummed now -- As I'm currently searching for a 3rd LaScala for my center and already have Heresy's for side surrounds and an XPA-5 on order.

Now, can others verify constant you have "hiss" coming from your tweeters (listening at a VERY close level to your speakers) for analog audio?

I would like other validations that my UMC-1 is in deed operating correctly (of course, if so, this noise will NOT work in my setup unfortunately).

[jason1976]

I don't think it is necessarily related to the voltage outputs. They are variable, not fixed at 7v. The USP-1 has a 9v max output and there haven't been any complaints about hiss that I'm aware of. If it was related to just voltage, then the USP-1 would be louder. Every other dedicated preamp manufacturer uses a higher output as well.

Others have reported no hiss, so it sounds like an anomaly. I would just call them.

[DYohn]

My setup is completely silent.

[solidstate]

Would you not damage the line level op amps on that Denon unit if you connected it directly to a speaker!!! That really wasn't a smart move buddy... and others never do this!

Post a picture of the RCA cables your using. I hope they aren't mainland "boxed" garbage. The best line level RCAs around for the money are Bluejeans LC-1, Outlaw Audio PCA and Emotiva's X-series though I haven't used them and don't honestly believe in a "balanced" single ended cable topology unless the shielding isn't terminated to the RCA or second conductor and is grounded via external ground. This means a wire coming outta the side of the cable near RCA then to grounding block not chassis ground. I've made cables like this using Mogami and Vampire RCAs. Prob the best sounding quasi balanced cable I've ever heard for single ended. IMHO I like the LC-1 because the center conductor is solid not stranded and this seems to help midrange IMHO and makes the highs crisper. Yup IMHO the LC-1 is the best single ended line level coaxial cable around bar none. To my ear anyway... and they are relatively cheap! Outlaw PCAs are even a bit better in terms of sound due to quasi "balanced" nature. Fantastic cables... Also the Outlaws are UP-OCC normally found in very expensive cables. Both are fantastic choices.

Solid-State

[roadrunner]

Have you tried connecting the CD Player through one of the digital inputs on the UMC-1 to see if the hiss is also present in the digital circuits? Optical digital cables are better at preventing electrical interference issues. If your hiss is being caused by RFI or other electrical line interference you will need to eliminate the cause. Do you have a line conditioner? Is your gear on a dedicated circuit? Do you have a halogen lamp nearby? ...flourescent lighting? ...decorative lighting using dimmer switches?

Do you have the necessary electrical testing equipment to check to see if you have any DC component on your AC line? Speaker noise may be caused by interference or noise on your AC line. Make sure there are no large appliances sharing the line, or halogen lamps or light-dimming Triac devices. You also want to make sure you separate the connector wires from the AC power cords. Did you try a different electrical outlet? Cheap or defective wall outlets can also contribute to line noise.

With speakers as sensitive as your Klipsch will reveal even minor electrical interference problems. I think I would call Emotiva first thing Monday morning and see if the hiss could be one of the FW problems that are being worked on. I would also ask if the XPA-2 is prone to hiss with speakers having very high sensitivity. I seem to remember Lonnie mentioning that other Emo amps may be a better match than the XPA-2 because of the hiss potential. I may be wrong about this -- I cannot remember well enough to be certain.

You mentioned trying several different sets of RCA cables. Where they all high quality, fairly new well construction RCAs?

Just curious, but with speakers with 100+ sensitivity rating is there some reason you are using the XPA Series amps? The UPA amps might just "play better" with your particular model of speaker.

Here's hoping you find the cause of your hiss this weekend. If not, let Lonnie or Nick know what you have tried. ;D

[jvgillow]

The UPA-2 and XPA-2 both have a 32dB gain structure so I don't believe you will notice any difference in hiss between the two models.

[dmillerc5]

solidstate, I do appreciate your concern for my old Denon. I really do not believe I caused any damage. I've never used super cheap cables like those which came packaged in my UMC-1 box. I also don't subscribe to exotic cables either. So right now my tests are using several pairs of the monoprice premium 3-foot cables. Yes, they are dirt cheap but I really don't believe these are causing interference. Not sure it matters here, but I ran the Denon's variable outs directly to the XPA-2 using a pair of these RCA cables. Very clean sound, no hiss as is being produced when running through the UMC-1.

Thanks roadrunner, I have not yet tried optical bypassing my Denon's DAC. I hope to do so soon (I just don't' have an optical cable right now).
I'm thinking the only real analog audio source I may have is my PC/soundcard.

I have no excuse right now for not having a line-conditioner in my setup, now that I finally have my UMC-1. Good news is that I just spoke with my brother who is going to let me borrow one his two APC-J15BLK units next week. I'll then do some more testing. I really don't have any test equipment for checking the circuit quality in the house at this time.

As far as why an XPA-2 with my efficient speakers.. we'll the answer for me is simple. Being a former drummer who absolutely loves music, my LaScalas when driven by the XPA-2 (loads of headroom) is, for me, like being in front of a "live" performance. I have a drum kit in my music room and it would be difficult
to know whether I'm playing live or playing a recorded track while blindfolded. I've got some sheffield lab drum tracks which could easily stress a system - and they sound incredibly "live".