Is this noise-floor normal behavior for my XPA-5?

[rontj]

In the past I created a thread about a hissing my amp makes at every power-on cycle.  This occurs just after the 5 channels are tested, and lasts approximately 1/2 second.  From this forum, and speaking with Emo tech, I'm convinced it's acceptable, although it has resulted in me leaving my amp powered on 24/7, which is fine.

However, recently I noticed the left speaker had an audible level of noise when standing near it, with a quiet room.  I found that odd.  So I did some testing, with even more odd results.

With the amp on, I unplugged the left RCA input, and no change in the noise.  So I power cycled the amp, and the noise grew louder.  I plugged in the left RCA input, power cycled, and the noise when back to the normal level, which was audible.  There was no such noise in the center or right speakers.

I pulled out my stand (not easy to do), to see if there were any power cables running in parallel to my signal cables, either to the receiver, or to the amp.  No, there were not.

I then swapped the left and surround left speaker-level output, and noticed they both had the same noise, so that was of no help.

I then unplugged all 5 RCA inputs, power cycled, and had the louder level of hissing.  With no inputs.  What is the source of the hissing?

Since I could find no pattern that was making sense, I reconnected everything, turned the amp on, and we're back to the normal low-level hissing and hum.  Again, my head needs to be within a couple feet of the speaker to hear it.  Is this expected behavior?  The amp is almost 3 months old.  I don't remember hearing such background noise when my speakers were connected to my receiver.  I would expect the speakers to be silent when no RCA signal cable is connected to the amp.  The amp is powered by a high-quality PSA passive (i.e., non power-limiting) power conditioner, which is in turn plugged in to a dedicated 20A circuit.

Thank you for your reply.

[jmasterj]

I have noticed a noise level in my XPA-100's. It's like a low level hum. I have to put my ear right up to the speakers, within six inches to hear it. It's in both channels but appears louder in the left speaker. At first I thought it was the tube preamp, so I dismissed it. But after reading your post I decided to investigate further. It occurs weather the amps are plugged into the line conditioner, or directly into the wall. It is there with no signal going to the amps, everything completely off. I think it could be from some sort of interference, or it could be wiring related.

I should note that I have experienced this with my Yakin tube amp but only with the Tekton M-Lores but not the MMG's. The funny thing is my BADA DC-222 Hybrid Integrated is dead quite with both pairs of speakers. The first time I experienced this was when I changed over from the MMG's to the M-Lores I attributed it to their 95db sensitivity. The MMG's are only 86db. Something else that I've noticed with the Yaqin is when I change from Class A to Class A/B I hear a distinct pop. This I did not experience with the MMG's. Again I attribute it to the sensitivity of the M-Lores.

I was surprised to hear the low level noise from my XPA-100's because I don't recall ever hearing a noise floor with solid state amps. I personally am not concerned with this. Mainly because it's barely perceptible, I had to look for it to hear it, and also because I have so many other sources of noise i.e. air, and heat, the refrigerator, barking dogs, and the neighbors. My system has to compete with all that. I can't even hear the that little hum.

I'm not suggesting that you dismiss it though. Because if I were hearing an elevated noise floor two feet away from my speakers it would be cause for concern for me. Maybe some other Lounge members with XPA-5's will help. I suggest you call Emotiva I don't believe that's expected behavior. Good Luck! j

[rontj]

Thanks for the reply, I appreciate it.  Yes, I will call Emo tech Monday.  The part that concerned me most was the noise level significantly increased when I unplugged all RCA source cables, and power cycled the amp.  That shouldn't make the noise level louder.  If anything, I think it should make it quieter.  The thought of having to send it back to Emo is probably what makes most owners not pursue potential problems with their amps.  I'll post the results of my conversation Monday.

[Gary Cook]

I've had an XPA-2 an XPA-3 and I now have an XPA-5 and all of them have been completely silent, no ground loop hum, no EMF interference static and no hiss whatsoever. Since you have noise with nothing connected to the amp but the speakers then logically there is either something in your environment that is getting the noise into the power supply and/or the speaker cables and hence into the amps or the amps themselves are creating the noise.

My amp noise testing process is pretty simple;
Swap the speaker cables with a known good one, preferably really short, that means moving a speaker close to the amp or vice versa.
Only have one speaker and swap it's connection to all channels of the amp.
I do have an old car speaker (just the driver) that I use for testing it's easier than moving big boxes around.
If the same noise is in all channels then swapping out the power cord might eliminate that as a cause.
If the above fails to reveal a source then I take the amp to my parents house, with the little car speaker and try it there, that eliminates local interference.
If the noise is still there after that process of elimination then there's a high % chance that it's the amp itself.
If it's only one channel with noise and you feel confident in swapping a circuit board then that is an option to save the freight shipping the amp back to Emotiva.
I'd it's all channels and/or you don't feel confident then send it back to Emotiva for service. But always call Emotiva first, they may have some specific suggestions for testing plus they will advise you of their service return process.

Hope that helps
Cherry
Gary

[rontj]

Gary, I tremendously appreciate the time you took to outline your recommended steps. I obviously need to set some time aside, but I will do this. I've honestly been disappointed with the hissing at startup (thus leaving it on 24/7), and then when I discovered the hissing and quiet hum yesterday, was even more disappointed.

I believe EMF interference can be airborne. I remember one time having a problem w/ my subwoofer because my cell phone was too close, causing my sub to emit static. And I think EMF interference can also be RF interference, thus perhaps my RF remote control system is the cause. My remote control RF processor is about 8" from the amp.

I will follow your steps, also adding one whereby I unplug my RF processor. I don't believe it's my power supply, though I'll test as you suggest. I have a dedicated circuit, with a quality conditioner. I'll also plug my amp directly into the dedicated 20A circuit, and also into a nearby non-dedicated 15A circuit.

Regarding the speaker cable, are you suggesting speaker cable can be a source of noise? Interesting. Considering this just gave me an "ah-ha" moment. I noticed last night that the center and right speakers seemed to have a much lower noise floor, than the other three speakers (5.1 system). Coincidentally, the two surround and left main speaker have the original 12 awg 8-year-old speaker cable, while the center and right main have newer (approx 2 years old or so) 10 awg cable. Using a 10' 10 awg new length of cable (in your first test) may reveal my problem, though I'm not sure how speaker cable could fail and/or be the cause of the noise. It's good Belden cable, but then how is the above part of this paragraph explained.

My left, center and right speakers are right next to my amp (in a 60" wide cabinet), thus easy to test.

Right now, I'm optimistic that it's either the old speaker cable, or the RF processor.

Are you saying that when you power-cycle your XPA-5, immediately after all channels are tested (the red light moves from left to right across all 5 channels), you have no short 1/2 second hissing? I've got to pay attention to see if that hissing is coming from all 5 speakers, or just the ones with the older cable. With your suggestions, I think I'll find the noise source.

Thank you.

[Gary Cook]

Last question first, I have no unwanted noise at all, anytime.

Speaker cable can act like an antenna, sucking in EMF from anywhere. I've had it so bad (my uncle's place) that even with the amp powered off I could hear it from the speakers.

Interconnects can be a worse antenna, as their EMF pick up gets amplified.

Sometimes, albeit rarely, the noise is coming in through the power supply network, so swapping internal outlets has no effect.

Eliminate the possibilities one by one, if none are left it must be the amp, then exercise the warranty.

Cheers
Gary

[emovac]

If you can't hear it from your listening position, don't worry about it too much. My Old Parasound Halo amps used to have a low emission hum, but you had to be near {at} the speakers to hear it. If you put your ear against the speaker and hear a low rumble, that is not unusual. If it is distracting, you'll need to figure it out. Might clean up your wiring and make sure the power circuit you are using isn't dirty. [Dimmers, motors, etc].

[rontj]

Gary, I need to completely disconnect my amp, except for power, and power-cycle.  With all cables disconnected, except power, if it still makes that 1/2 second hiss after all channels are tested, that, to me indicates a problem with the amp.  I will call Emo on this, but I never considered testing in this manner before your post.  I know other owners of the XPA-5 have said their units do not emit that 1/2 second of hissing.  So, mine shouldn't either.

Thanks for your help.  Eager to run this tests and see what I find.

[aud]

Jan 19, 2014 2:51:55 GMT -5 emovac said:

If you can't hear it from your listening position, don't worry about it too much. My Old Parasound Halo amps used to have a low emission hum, but you had to be near {at} the speakers to hear it. If you put your ear against the speaker and hear a low rumble, that is not unusual. If it is distracting, you'll need to figure it out. Might clean up your wiring and make sure the power circuit you are using isn't dirty. [Dimmers, motors, etc].

I see you own some wired 4 sound equipment . If one of them is an amplifier, is it dead quiet with electronic and mechanical (T- former) noise? I'm thinking of buying a couple of their mono blocks. I had the same problem with my Halo's. In fact I'm tired of the noise I hear with a lot of gear I have purchased from different Mfg's. I have done all the right things over the past two years including installing a sub panel with four 30 amp dedicated circuits. I'm coming to the conclusion that the Mfg's are not paying enough attention to their grounding and power supply circuit designs, but I'm just a hobbyist, not an engineer.

[rontj]

Jan 19, 2014 2:51:55 GMT -5 emovac said:

If you can't hear it from your listening position, don't worry about it too much. My Old Parasound Halo amps used to have a low emission hum, but you had to be near {at} the speakers to hear it. If you put your ear against the speaker and hear a low rumble, that is not unusual. If it is distracting, you'll need to figure it out. Might clean up your wiring and make sure the power circuit you are using isn't dirty. [Dimmers, motors, etc].

Thanks for your reply - I appreciate it.  Well, I may reach that conclusion of not worrying about it too much.  But I first want to go through the steps Gary suggested.  Other XPA-5 owners have said their amps are dead quiet, while others have said theirs emit a brief hiss after power-cycle, as mine does.  And, the cause of my speaker hiss/hum (that I can only hear when standing close, but likely not from the listening position), may be something I can find with minimal to moderate effort, which would surely worth the time to me.

[Gary Cook]

Jan 19, 2014 17:13:06 GMT -5 rontj said:

Thanks for your reply - I appreciate it.  Well, I may reach that conclusion of not worrying about it too much.  But I first want to go through the steps Gary suggested.  Other XPA-5 owners have said their amps are dead quiet, while others have said theirs emit a brief hiss after power-cycle, as mine does.  And, the cause of my speaker hiss/hum (that I can only hear when standing close, but likely not from the listening position), may be something I can find with minimal to moderate effort, which would surely worth the time to me.

I should have asked this before, what is your power up order? I turn on the power amp with the trigger from the USP-1, so the power amp is the last item turned on, that's how I have always set it up, even when using a programmed remote. Hence the power amp always has a source to lock onto before it amplifies/emits any sound. I have never tried it with Emotiva power amps but some other brands don't like being powered up with no source and emit noise until they lock.


Cheers
Gary

[aud]

Jan 19, 2014 18:20:02 GMT -5 Gary Cook said:

Jan 19, 2014 17:13:06 GMT -5 rontj said:

Thanks for your reply - I appreciate it.  Well, I may reach that conclusion of not worrying about it too much.  But I first want to go through the steps Gary suggested.  Other XPA-5 owners have said their amps are dead quiet, while others have said theirs emit a brief hiss after power-cycle, as mine does.  And, the cause of my speaker hiss/hum (that I can only hear when standing close, but likely not from the listening position), may be something I can find with minimal to moderate effort, which would surely worth the time to me.

I should have asked this before, what is your power up order? I turn on the power amp with the trigger from the USP-1, so the power amp is the last item turned on, that's how I have always set it up, even when using a programmed remote. Hence the power amp always has a source to lock onto before it amplifies/emits any sound. I have never tried it with Emotiva power amps but some other brands don't like being powered up with no source and emit noise until they lock.


Cheers
Gary

Very good point, Gary! I do the same thing but totally forgot about it. Proper trigger sequence WILL make a difference on power up.

[emovac]

Jan 19, 2014 17:05:10 GMT -5 aud said:

Jan 19, 2014 2:51:55 GMT -5 emovac said:

If you can't hear it from your listening position, don't worry about it too much. My Old Parasound Halo amps used to have a low emission hum, but you had to be near {at} the speakers to hear it. If you put your ear against the speaker and hear a low rumble, that is not unusual. If it is distracting, you'll need to figure it out. Might clean up your wiring and make sure the power circuit you are using isn't dirty. [Dimmers, motors, etc].

I see you own some wired 4 sound equipment . If one of them is an amplifier, is it dead quiet with electronic and mechanical (T- former) noise? I'm thinking of buying a couple of their mono blocks. I had the same problem with my Halo's. In fact I'm tired of the noise I hear with a lot of gear I have purchased from different Mfg's. I have done all the right things over the past two years including installing a sub panel with four 30 amp dedicated circuits. I'm coming to the conclusion that the Mfg's are not paying enough attention to their grounding and power supply circuit designs, but I'm just a hobbyist, not an engineer.

I have a Wyred4Sound Integrated STI-500 (250x2), the MC7x250 (250x7), and the base DAC-2. The stuff has a dead quiet noise floor. I've had the setup a couple of years, and am extremely happy with it. I have nine channels operational, which is the same as I had with the Parasound gear (Halo P3, Halo A23x2, HCA1205a). The Parasound had the low rumble at the speaker, and everything was operated through a Belkin PF60 (or APC H15) in a dedicated 20 amp circuit with 10/3 to the panel. Although I don't think I need it at this point, I have the amps running through a PS Audio Humbuster 3 (mechanical hum barrier outlet - removing DC noise) just in case.

The Parasound low rumble was distracting standing next to the speaker, but I concluded that's not really where I was spending my time listening, and just dealt with it. I checked out the Wyred stuff at an audio show, and started with the DAC, and picked up the amps shortly thereafter. If you are interested in the Wyred stuff, they do have some try and buy options. Be prepared to buy after you try - my guess is you wont what to be without them after you try it.

[aud]

Jan 19, 2014 18:47:05 GMT -5 emovac said:

Jan 19, 2014 17:05:10 GMT -5 aud said:

I see you own some wired 4 sound equipment . If one of them is an amplifier, is it dead quiet with electronic and mechanical (T- former) noise? I'm thinking of buying a couple of their mono blocks. I had the same problem with my Halo's. In fact I'm tired of the noise I hear with a lot of gear I have purchased from different Mfg's. I have done all the right things over the past two years including installing a sub panel with four 30 amp dedicated circuits. I'm coming to the conclusion that the Mfg's are not paying enough attention to their grounding and power supply circuit designs, but I'm just a hobbyist, not an engineer.

I have a Wyred4Sound Integrated STI-500 (250x2), the MC7x250 (250x7), and the base DAC-2. The stuff has a dead quiet noise floor. I've had the setup a couple of years, and am extremely happy with it. I have nine channels operational, which is the same as I had with the Parasound gear (Halo P3, Halo A23x2, HCA1205a). The Parasound had the low rumble at the speaker, and everything was operated through a Belkin PF60 (or APC H15) in a dedicated 20 amp circuit with 10/3 to the panel. Although I don't think I need it at this point, I have the amps running through a PS Audio Humbuster 3 (mechanical hum barrier outlet - removing DC noise) just in case.

The Parasound low rumble was distracting standing next to the speaker, but I concluded that's not really where I was spending my time listening, and just dealt with it. I checked out the Wyred stuff at an audio show, and started with the DAC, and picked up the amps shortly thereafter. If you are interested in the Wyred stuff, they do have some try and buy options. Be prepared to buy after you try - my guess is you wont what to be without them after you try it.

Thanks very much for your detailed response! We have a lot in common with our electrical supply power and Parasound experience.

[rontj]

Jan 19, 2014 18:20:02 GMT -5 Gary Cook said:

Jan 19, 2014 17:13:06 GMT -5 rontj said:

Thanks for your reply - I appreciate it.  Well, I may reach that conclusion of not worrying about it too much.  But I first want to go through the steps Gary suggested.  Other XPA-5 owners have said their amps are dead quiet, while others have said theirs emit a brief hiss after power-cycle, as mine does.  And, the cause of my speaker hiss/hum (that I can only hear when standing close, but likely not from the listening position), may be something I can find with minimal to moderate effort, which would surely worth the time to me.

I should have asked this before, what is your power up order? I turn on the power amp with the trigger from the USP-1, so the power amp is the last item turned on, that's how I have always set it up, even when using a programmed remote. Hence the power amp always has a source to lock onto before it amplifies/emits any sound. I have never tried it with Emotiva power amps but some other brands don't like being powered up with no source and emit noise until they lock.


Cheers
Gary

I HAD the amp powered on by a 12v trigger from my receiver, and after hearing the 1/2 second hiss upon every single power up for 2 months, I disconnected the 12v cable and leave the amp on 24/7.  That of course eliminated the hissing problem (or bypassed it, anyway), but the continual quiet hissing/rumble remains.

Your explanation above likely explains why the amp had the loudest hissing when I had all input RCA disconnected.  Upon disconnecting all 5 RCA source cables, and power-cycling the amp, the hissing was quite loud.  If the Emotiva hisses if no sources are connected, I won't be able to test the amp alone.  In other words, I had planned on disconnecting everything from the amp, except the power cable, and power cycling, to see if it was stone quiet.  But now, from what you're saying, this test will yield no helpful information.

I just turned on my system (activity TiVo), played a recording thus generating audio, manually turned off my XPA-5, waited a few seconds, manually turned it on, and immediately after the 5-channel test (lights go across all 5 channels left to right), again there was a 1/2 second hiss IMMEDIATELY preceding the TiVo audio.

[rontj]

Jan 19, 2014 18:47:05 GMT -5 emovac said:

Jan 19, 2014 17:05:10 GMT -5 aud said:

I see you own some wired 4 sound equipment . If one of them is an amplifier, is it dead quiet with electronic and mechanical (T- former) noise? I'm thinking of buying a couple of their mono blocks. I had the same problem with my Halo's. In fact I'm tired of the noise I hear with a lot of gear I have purchased from different Mfg's. I have done all the right things over the past two years including installing a sub panel with four 30 amp dedicated circuits. I'm coming to the conclusion that the Mfg's are not paying enough attention to their grounding and power supply circuit designs, but I'm just a hobbyist, not an engineer.

The Parasound low rumble was distracting standing next to the speaker, but I concluded that's not really where I was spending my time listening, and just dealt with it. I checked out the Wyred stuff at an audio show, and started with the DAC, and picked up the amps shortly thereafter. If you are interested in the Wyred stuff, they do have some try and buy options. Be prepared to buy after you try - my guess is you wont what to be without them after you try it.

Did you ever find the cause of the low rumble heard through the speaker?  Sounds like it may have been equipment related?

[rontj]

Separate question that may help me identify my problem with the quiet hissing and hum.  From my receiver to my XPA-5, a given volume level, say -30dB, seems no louder now than compared to my receiver powering my speakers.  Does this seem correct?  I would have thought that, due to much more power coming from the Emo amp than my receiver, the same indicated volume level would be at least somewhat louder with the speakers being powered by the amp.

[rontj]

Jan 18, 2014 17:41:25 GMT -5 Gary Cook said:

Swap the speaker cables with a known good one, preferably really short, that means moving a speaker close to the amp or vice versa.
Only have one speaker and swap it's connection to all channels of the amp.

Gary, on the first test, should all 5 RCA input cables be connected to the amp?  Should a source device being outputting audio to the receiver, and thus to the amp?

[emovac]

Jan 19, 2014 20:58:31 GMT -5 rontj said:

Jan 19, 2014 18:47:05 GMT -5 emovac said:

The Parasound low rumble was distracting standing next to the speaker, but I concluded that's not really where I was spending my time listening, and just dealt with it. I checked out the Wyred stuff at an audio show, and started with the DAC, and picked up the amps shortly thereafter. If you are interested in the Wyred stuff, they do have some try and buy options. Be prepared to buy after you try - my guess is you wont what to be without them after you try it.

Did you ever find the cause of the low rumble heard through the speaker?  Sounds like it may have been equipment related?

No, it was an inherent issue with the equipment. I did have a separate ground loop issue which I solved using a ground loop RCA interconnect, but was not the low volume rumble I had mentioned in the earlier post. In my case, the rumble was only audible at the speakers, not in the listening position. I learned to live with it. My new equipment is dead silent, even standing next to the speakers.

[aud]

Jan 19, 2014 20:58:31 GMT -5 rontj said:

Jan 19, 2014 18:47:05 GMT -5 emovac said:

The Parasound low rumble was distracting standing next to the speaker, but I concluded that's not really where I was spending my time listening, and just dealt with it. I checked out the Wyred stuff at an audio show, and started with the DAC, and picked up the amps shortly thereafter. If you are interested in the Wyred stuff, they do have some try and buy options. Be prepared to buy after you try - my guess is you wont what to be without them after you try it.

Did you ever find the cause of the low rumble heard through the speaker?  Sounds like it may have been equipment related?

I sure emovac will answer soon. In the mean time I'll tell you what happen to me. With my Halo amp, I decided to send it to Parasound even though I had to pick up the freight. After two weeks, they told me everything was within design specifications and nothing was wrong with it. That's when I decided to look elsewhere for audio equipment.