High pinched whistling

[VDS]

Hi,

set up new speakers, everything good.  Moved them to new location in house, (started in studio in separate building on property), same equipment and now I’ve got a persistent very high pitched whistle, whine, ear piecing frequency.

Not very loud, but clearly audible,  sure I would have heard it in previous location, heard as soon as I got system up and running in new location.
Seems to be coming from the Xilica 4080xp, stops when I turn Xilica off.  

Anybody with Xilica or other DSP experience this?

Could it be grounding at this high pitch? Subtly different electrical supply in home vs studio? 
many ideas on how to troubleshoot this?

thanks for any perspective, Ted
 

[Chris A]

You probably need to measure them again in the new room, in the position within the room that you've selected.   It could be that the measurements done in another room had a systemic microphone placement issue that was incorporated into the Xilica settings.  The measurements will also identify the frequency content and intensity of the noise you're hearing. 

 

Moving loudspeakers after dialing them in in-room resets almost everything in my experience--especially below the room's transition frequency (Schroeder frequency). 

 

It's also nice to provide a picture of your loudspeakers and your room so that those offering their opinions can be better calibrated.

 

Chris

[VDS]

Chris, I did measure and made some adjustments, I’ve got all 100-15,000hz levels to within 6dB from peaks to valleys , after 15,000hz it rolls off. “Hum” Is very high frequency. 
 

[Chris A]

Also, using RCA (unbalanced) connections are much more susceptible to electrical noise from supplied power--dimmers, other equipment in-room, etc. can produce significant amounts of "common mode" noise, and that can even extend into upper frequencies.

 

Chris

[VDS]

4 minutes ago, Chris A said:

Also, using RCA (unbalanced) connections are much more susceptible to electrical noise from supplied power--dimmers, other equipment in-room, etc. can produce significant amounts of "common mode" noise, and that can even extend into upper frequencies.

 

Chris

I do have xlr to rca for preamp our to Xilica in, and xlr to rca from Xilica to high frequency amp.  These are inexpensive cables, I could look for higher  quality xlr to rca cables?

[Chris A]

I think it's better to re-route your signal cables to keep them as far away from the power cables as possible, turn off any other equipment, and especially turn off any light dimmers.  Paying more money for unbalanced RCA cables probably won't change the noise situation nearly as much as the techniques in the first sentence of this post.

 

EDIT: Also make sure that all connections are through one power outlet (single ground on one power strip). My flat panel screen (on another power output) produced so much power noise that I had to convert the S/PDIF (digital) connection to a long TOSLINK optical cable.  Problem solved.

 

Chris

[PrestonTom]

Come on guys ... this is just a guessing game at this point.

 

The OP needs to be more articulate by what he means by "whistling". Please be more specific, otherwise we are only guessing and any advice you get will be very suspect. 

[VDS]

1 minute ago, PrestonTom said:

Come on guys ... this is just a guessing game at this point.

 

The OP needs to be more articulate by what he means by "whistling". Please be more specific, otherwise we are only guessing and any advice you get will be very suspect. 

Trying to describe sound is always difficult.  Its a very high pitched, over 15,000hz?, piercing sound.  not loud, but audible between songs. The high pitch is really is unpleasant on the ears.  it does not change volume when raising volume, or preamp gain.  if i turn off xilica it stops,

[VDS]

Separated all power cables from signal cables, no change.

[Chris A]

4 hours ago, PrestonTom said:

Come on guys ... this is just a guessing game at this point.

Not so much...

 

4 hours ago, VDS said:

Its a very high pitched, over 15,000hz?, piercing sound. 

Try reducing PEQ #7 boost at 15 kHz and listening to see if that affects the noise quiescently.

 

 

It could be that the Axi2050 is just now breaking in.  The orange curve is the raw response that I measured in my listening room after the brand new driver that I borrowed had broken in a few hours, and the blue curve is what you measured with your Axi2050:

 

 

I don't see a lot a difference at the frequencies that you mention.  It sounds like a noise issue--like a dimmer switch would produce.

 

Chris

[VDS]

The sound is similar to how your ears ring after being around very load noise for too long. 

[VDS]

5 hours ago, Chris A said:

 

 

[Chris A]

42 minutes ago, VDS said:

Unrelated topic, why does the non-EQed Celestion drop so quickly from 2k?  It almost seems like a mid driver for a 3 way.

 

There are at least two factors:

 

1) the effect of the K-402, which is a controlled directivity horn (all full-range controlled directivity horns always show this characteristic), and

 

2) the effect of the design of the clamped axisymmetric diaphragm in the Axi2050, which was designed to cover the full range of output using controlled directivity horns, which produces both low frequencies (a consequence of its very large diaphragm area) and high frequencies (a very carefully designed and developed non-dome diaphragm). This is the effect of the large diaphragm reaching its "mass corner" but still able to produce large amounts of output even up to 15+ kHz without the diaphragm breaking into coupled modes of non-pistonic vibration--also known as diaphragm breakup or chatter. 

 

The design of the Axi2050 requires EQ, and I believe its design represents a very large step forward in compression driver technology.

 

45 minutes ago, VDS said:

The sound is similar to how your ears ring after being around very load noise for too long. 

You can send me a REW .mdat measurement file.  Perhaps it will show the issue. 

 

Also, you can record an "RTA" steady state measurement with no driving signal within REW to see the problem frequencies-placing the microphone at or just inside the mouth of the K-402. Those plots look like this (1/48th octave smoothing):

 

 

 

Chris

[mikebse2a3]

16 hours ago, VDS said:

Trying to describe sound is always difficult.  Its a very high pitched, over 15,000hz?, piercing sound.  not loud, but audible between songs. The high pitch is really is unpleasant on the ears.  it does not change volume when raising volume, or preamp gain.  if i turn off xilica it stops,

 

Just for clarity;

 

Is this noise always audible without music..?

Is the noise audible in both channels..?

Is the noise in the HF only or do you also have noise in the LF also..?

Do you have all the equipment plugged into a common power strip..?

Make sure all light dimmers are turned off when testing for the noise..?

How long are your interconnect cables for the pre-amp to xilica and xilica to amplifiers…?

What models are your pre-amp and amplifiers for HF and LF..?

 

Does any of the unbalanced equipment (pre-amp or amplifiers have) have 2 prong non-polarized ac plugs….? (If polarized 1 prong is larger than the other and can only be plugged in in one direction which shouldn’t be defeated where as non-polarized plugs having both prongs the same size and in those cases it can be tried in both directions which may lead to finding one direction is quieter than the other and should be tried.

 

Since the noise doesn’t change with volume control changes the noise issue is being introduced somewhere between the pre-amp, xilica, amplifiers and the associated interconnecting cables and equipment ac connections.

 

18 hours ago, VDS said:

Not very loud, but clearly audible,  sure I would have heard it in previous location, heard as soon as I got system up and running in new location.
Seems to be coming from the Xilica 4080xp, stops when I turn Xilica off.

 

Again first Verify any noise sources such as dimmers or other type of equipment that might emit RF Noise is turned off during testing..!!!

 

 

If you try unhooking the the pre-amp cables from the xilica input does the noise stops or persist…?

If the noise stops the issue is between pre-amp and xilica and is most likely an interconnect or ground loop issues. (The ground loop issues can be solved with attention to AC Connection of unbalanced equipment (if non-polarized ac plug orientation helps) or an Isolation Transformer such as Jensen ISO-MAX products.)

If the noise persist then the problem is between the xilica and amplifiers.

 

If problem is between xilica and amplifiers then disconnect all interconnects from the xilica to amplifiers and verify if the noise stops or persist.

If the noise persist then the noise is being introduced at the amplifiers.

If the noise stops you most likely have interconnect or ground loop issues between xilica and amplifiers. I suggest you reconnect one amplifier at a time starting with the LF amplifiers and then HF amplifiers to find which amplifiers are associated with the ground loop issues. The ground loop issues can be solved with attention to AC Connection of unbalanced equipment (if non-polarized ac plug orientation helps) or an Isolation Transformer such as Jensen ISO-MAX products.

 

miketn

[babadono]

^All very good advice from Mike. @mikebse2a3. I would add that when the Xilica is turned off there are output relays that switch to the "Mute" position. This removes the output of the D/A section of the unit and shorts pin 2 to pin 3 on the XLR output connectors. It sounds like from @VDS s description that all is well when this happens which implies the power amps/speakers and cabling from Xilica output to power amp inputs is good.

[VDS]

12 minutes ago, mikebse2a3 said:

Is this noise always audible without music..?

Is the noise audible in both channels..?

Is the noise in the HF only or do you also have noise in the LF also..?

Do you have all the equipment plugged into a common power strip..?

Make sure all light dimmers are turned off when testing for the noise..?

How long are your interconnect cables for the pre-amp to xilica and xilica to amplifiers…?

What models are your pre-amp and amplifiers for HF and LF..?

AHHA, Finally found something. When i unplug interconnects from Pass Amp noise stops!  Pass is single ended only, no XLR

 

Always audible, except when i turn Xilica off and leave everything else on.

Both compression drivers, (2 way speakers)

All equipment plugged into power strip.  Tripp Lite. isobar ultra 

No dimmers in the house

All interconnects 3' - 6'

All power cables are standard 3 prong audio, except bluesound Node 2i, ungrounded 2 prong 

Pass xa25 highs,  Crown K1 woofers, Aric Audio Motherload pre 6SN7

 

Separated all power cables from signal cables

Nothing else electical in room turned on, lamps, tv, 

 

Tried to match pitch with tone generator on phone, probably 6000-10,000hz 

[VDS]

2 minutes ago, VDS said:

AHHA, Finally found something. When i unplug interconnects from Pass Amp noise stops!  Pass is single ended only, no XLR

But that make sense right, your literally creating a gap in signal chain, or am i off base?

Wondering  if the connection to the high frequency amp causes problem, or just doesnt allow problem to get to the speakers?

[Chris A]

6 minutes ago, VDS said:

When i unplug interconnects from Pass Amp noise stops!

How much high frequency "whistling"  is there?  (That's the rationale for the RTA measurement.)  Which model of "Pass amplifier" are you using?

 

1 minute ago, VDS said:

your literally creating a gap in signal chain, or am i off base?

I think the latter. 

 

Are you using something like a Jensen ISO-MAX isolator in-line between the Xilica and Pass amplifier?  I found this filter is required for my First Watt F3 amplifier (with unbalanced-only RCA connections), but not when I use a Crown D-75A amplifier--which has balanced/XLR connections.

 

Chris

[VDS]

No isolator, would certainly be willing to try one.

RTA is a little confusing, many options i dont understand in control pop up window, did set to 1/48th smoothing though

 

 

[PrestonTom]

Well it looks like there is progress. This is not the first time someone has had problems going from balanced to unbalanced, although it is curious that that the "junk" coming through is at such a high frequency.

 

I assume the cable is XLR at one end and RCA at the other (IOW, no additional connectors added to an otherwise three wire cable). This probably is not the problem, but have you measured whether the pin 1 and pin 3 on the XLR side side of the cable are electrically tied together ?