AudioCircle
Industry Circles => GR Research => Topic started by: mlundy57 on 27 Aug 2015, 10:17 pm
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I finally got around to troubleshooting the hissing/crackling sound in my Wedgie system that could only be heard when music wasn't playing or was playing at very low levels (-40 on the volume display).
I traced it to the in-line filters I built. Also, if I touched the filter housing and moved it just a little I could set up a much louder hum that could be heard over the music. Touch and slightly move it again and the hum would go away.
Here's a picture of the filter.
(http://www.audiocircle.com/image.php?id=126930)
The housing is a non-conductive schedule 80 PVC electrical box. As you can see, the channels are separate and do not touch each other. When I check for continuity I get readings I would expect i.e. shorts going input to output through the caps and through the by-pass legs, opens between positive and negative parts of each leg, the outputs of the filtered and by-pass legs and opens between the two channels.
Correction: I put a new battery in my meter and am getting different readings. With the new battery the readings are as described above except that I now get opens through the caps. This is the same whether I check at the Cardas connectors or the leads coming out of the caps.
The connectors are Cardas.
Any thoughts/ideas on what is going on here?
Thanks,
Mike
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Mike, can you isolate the noise to a specific channel or is it in both equally? Also, does it remain constant on both sides of filter? Meaning on the pass thru and filtered sides.
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Peter,
It's both equally. When I take the filter out of the system and run direct from the preamp to the power amp the noise goes away.
It is only on the filtered legs to the Wedgies. It is not occurring in the subs via the by-pass leg. Also, it is most pronounced in the tweeters.
I edited the readings in my earlier post. My meter was acting up so I put a new battery in and got different readings through the caps.
Mike
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Mike,
The reading across the filter caps should read open, not shorted. The ground legs should read short as you describe.
Sounds like some of the solder is possibly shorting across the input or output RCA connections and might be causing the problem.
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Does it occur with only one amplifier on?
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Mike,
The reading across the filter caps should read open, not shorted. The ground legs should read short as you describe.
Sounds like some of the solder is possibly shorting across the input or output RCA connections and might be causing the problem.
HAL,
I'll borrow my wife's magnified lamp to take a closer look
Does it occur with only one amplifier on?
Folsom,
The way I trouble shot it was to start with everything on and the noise coming from the Wedgies.
First I disconnected the speaker cables from the power amp, everything still on to see if the cables were picking up noise. Nope, all sound, including the noise went away.
So I plugged the speaker cables back in, sound and noise came back.
Then I disconnected the RCA input interconnect from the power amp. Sound and noise went away so I plugged the interconnect back in to the power amp. Sound and noise came back.
Next I disconnected the other end of the power amp input interconnect from the filter. That's when I noticed the increase and decrease in the noise when I moved the filter box.
At this point I suspected the filter was the culprit so I connected the preamp directly to the power amp and the sound came back but the noise was gone.
Culprit identified, the in-line filter.
Next step is going to be to follow HAL's suggestion and carefully inspect the connections under magnification. If this is the problem, I expect to find bad connections on the output side of the filter legs. If the bad connections were on the input side I would expect to have heard the noise in the subs as well but I didn't.
Mike
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I'd almost guarantee it's a grounding issue. There's a solution for that, but it's somewhat still in the testing phase. It works fab for me, and hard to say with another forum member whom has yet to discern what qualities are with what piece of equipment. Also, Tyson has my unit ATM so maybe he'll be able to say shortly.
If you'd like I can provide you with the simple plans.
Also you might be surprised about what can interact that's insulated/non-conductive if any capacitance forms between it. A non-grounded case is prone towards this without a doubt. Is there any affect on noise if you touch the case and an RCA barrel ( ground ) ?
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I checked all the solder connections. There is no cross contamination between the + and - positions on any of the connectors.
Not sure how grounding fits in. Since the noise doesn't exist when the preamp is connected directly to the power amp, only when the signal passes through the filter, if it is a grounding issue it would have to exist in the filter box wouldn't it?
Right now I have the filter out of the system so I can't try touching the case and barrel at the same time. However, the case itself is non-conductive (it's designed to safely house exterior electrical connections) so it should not act as a ground.
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I can't help if you do things entirely different, or tell me you don't think it's going to matter. Grounding just within the box? No....... Ground paths exist between all the components and back to your breaker box. Which ones are active, and how active, is another story. If the equipment is smart it is likely to break/prevent unwanted paths but typically they exist even when "disabled", as an inactive or relatively inactive path.
Don't bother touching without it in the system.
Does it make the noise when the filter is in but only with one amp plugged into it?
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It sounds like it is somehow creating a ground loop.
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It sounds like it is somehow creating a ground loop.
Right, which is part of the information I'm asking for, so hopefully we'll get it solved in short order.
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the crackling sound is a result of bad connection
you cant inspect connections with a magnified glass
you have to resolder/reheat them (all)
good luck
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I'll put it back in the system in the morning and check out the touching and one amp at a time
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the crackling sound is a result of bad connection
you cant inspect connections with a magnified glass
you have to resolder/reheat them (all)
good luck
In both channels? Hm, now that isn't easy to locate. I'm not convinced it's not RF or ground noise. You might be impressed what sorts of odd noises can jump on ground when the loop goes all the way back to the breaker box.
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yes in both channels if it is a stereo amp with common ground
i dont know what filter is this,it appears as coupling caps and distribution
network at the same time...
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yes in both channels if it is a stereo amp with common ground
i dont know what filter is this,it appears as coupling caps and distribution
network at the same time...
George, there's no common ground in the filter for R/L besides parasitic capacitance. This leave the aux amp that isn't used without the filter as a place to have a common broken solder connection. This is unlikely given that amps preferably don't mix the grounds right at input, in the audiophile world (commonly).
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Have you tried disconnecting the woofers on the bypass side of the filter to see if that is causing the ground loop?
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Have you tried disconnecting the woofers on the bypass side of the filter to see if that is causing the ground loop?
The woofer's themselves won't contribute to the group loop likely unless maybe if the subwoofer amplifier was some estranged balanced output device or CSS driven without a ground/virtual ground... etc. But disconnecting the amplifier for the subwoofers as I suggested would in fact tell us just thus! Perhaps that's what you mean Greg, but I just wanted to make sure because not having speakers connected with a powered amplifier isn't advisable.
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the crackling sound is a result of bad connection
you cant inspect connections with a magnified glass
you have to resolder/reheat them (all)
good luck
this seems more likely to me as well, especailly if you are able to touch the filter and move it slightly resulting in a change in the crackle / noise.
If it were a ground loop, would it not be there with just the pre and amp regardless of the filter being added , the filter isn't adding an additional ground, it's just inline between the two components
The last ground loop I dealt with was being generated by the coax feeding my cable box that was in my system, it was introducing an additional ground via the cable itself. But it was more of a 60 hz hum, not a crackle that changed when i touched the box
I don't see how that filter could be adding an additional ground aside from something being shorted to the existing ground in that circuit
EDIT DOH, sorry, I wasn't paying close enough attention... didn't even realize there was a bypass passing to the sub amps. After re-reading I too would disconnect those amps and see where that leads
jay
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I agree with you
however
this filter is strange... :green:
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The woofer's themselves won't contribute to the group loop likely unless maybe if the subwoofer amplifier was some estranged balanced output device or CSS driven without a ground/virtual ground... etc. But disconnecting the amplifier for the subwoofers as I suggested would in fact tell us just thus! Perhaps that's what you mean Greg, but I just wanted to make sure because not having speakers connected with a powered amplifier isn't advisable.
Yes, that is what I was saying. If the sub amps are connected to the bypass and are plugged into a different outlet it could be causing a ground loop. What's puzzling to me is the crackle sound Mike is hearing?
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I've put the filter back in. Touching the body and the barrels did not make a difference, nor did unplugging the interconnect to the sub plate amps.
For clarity, the speaker system is the open baffle Wedgies on top driven by a NAD C372 power amp, and 3x8" servos in an H-Frame on the bottom driven by Rythmik HX300 plate amps. All of the components in the chain are plugged into a Panamax power conditioner which is plugged into a single wall outlet.
Also, the sound I am talking about is not a low frequency hum coming from the woofers but rather a higher frequency hiss/crackle coming from the tweeters. The best way I can think of to describe it is that it sounds like static, like the sound you hear from a radio that is not tuned into a station, only muted. It is in both speakers. It is louder on the back side of the tweeter than the front. It is not loud enough to hear over music playing at a normal volume unless I put my ear right up to the tweeter. However, when the music is playing very softly or everything is on but no music is playing the sound can be heard from the listening position.
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Okay, that doesn't sound like a ground loop now.
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Could it be a broken interconnect? A broken interconnect can radiate RF into both channels potentially. You could check by swapping the extra set used with the filter, with another for the subs or such.
I would move to a metal box and ground it to the jacks incoming. Then wire in star pattern to them, instead of series like now.
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If the extra set of IC's youi've added checks out ok, I'd actually get he iron out and just try setting it up as a straight filter, run the ground direct to the outputs of the filter and skip the bypass for now. I know , it shouldn't make a difference but it's a place to start.
If that happens to make the difference, I'd then try re-doing the bypass but without the series ground like Folsom said , even if you don't replace the box right away.
jay
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I'll check out the possibility of a bad interconnect after while. Now it is time for some more wetsanding, this time to 800 grit, on the Wedgies I'm building and shoot another coat of poly. Then I get to sand to 1,200 ...
Mike
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I would also check for loose speaker connections, loose servo connections, etc.
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Mike, perhaps you've done it before, but most polyurethanes don't "burn in" like solvent finishes (they typicallly coalesce) which means they are particularly difficult to cut and buff. If you happen to sand through the top layer you get a halo where top coat meets one below. Disregard if you're using catalyzed urethane automotive finishes.
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I would also check for loose speaker connections, loose servo connections, etc.
That cannot be true with what has already been stated.
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Any luck Mike?
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As a matter of fact, I am totally flummoxed. After extensive swapping of every component, the noise turns out to be intermittent and unrelated to any of the components, interconnects or speaker cables. It is not even related to a particular file on the computer because sometimes a particular track will have noise and other times that same track will not have the noise even with no change in equipment. The same goes when I play the same track directly from the CD rather than from the computer.
I have tried both solid state and tube components with the same result, sometimes the noise is there, other times it is not. This is why I hate electrical problems.
The only thing I can think of I haven't tried is something that is on the drawing board but not feasible at this time. That is, when I remodel this room I am going to pull a dedicated 20 amp circuit from the panel box just for the AV equipment. That's about a year away though.
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Something in the house is on and generating RFI. Go around the house and turn off or shut everything down until it's gone.
My daughter installed a booster for her modem once and it put a ton of noise on my system.
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Something in the house is on and generating RFI. Go around the house and turn off or shut everything down until it's gone.
My daughter installed a booster for her modem once and it put a ton of noise on my system.
Or get Dave to send you an Uber :) I recently had the opportunity to compare the uber to my Minibuss, I was shocked at the difference as the other fellow i had over to audition the two pieces.
I'd bet it is a fredge or a freezer comprssor cycling on and off once in a while. If not, like Danny says, you could try shutting down various circuits to try and narrow the search
jay
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Something in the house is on and generating RFI. Go around the house and turn off or shut everything down until it's gone.
My daughter installed a booster for her modem once and it put a ton of noise on my system.
Now that you mention it, I have recently installed a WiFi booster in the hallway outside my listening room to try and keep the wifi tablet I use to control JRiver from dropping out. Next time I hear the noise I'll unplug it and see if that helps.
Jay,
Something like that may end up being necessary because shutting the house down so I can listen to music will fly about as well as a lead balloon. :nono:
Mike
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Now that you mention it, I have recently installed a WiFi booster in the hallway outside my listening room to try and keep the wifi tablet I use to control JRiver from dropping out. Next time I hear the noise I'll unplug it and see if that helps.
Jay,
Something like that may end up being necessary because shutting the house down so I can listen to music will fly about as well as a lead balloon. :nono:
Mike
Just shut stuff down one at a time until you find it.
I'd be willing to bet money on the WiFi booster. Those are really bad. Some of them actually send a signal down your electrical wiring and use it as an antenna. And here we are trying to do everything we can to get all that noise off the line. :duh:
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Just shut stuff down one at a time until you find it.
I'd be willing to bet money on the WiFi booster. Those are really bad. Some of them actually send a signal down your electrical wiring and use it as an antenna. And here we are trying to do everything we can to get all that noise off the line. :duh:
Danny,
You just brought up another potential issue. I have set up a wired home network throughout the house but since I couldn't run ethernet cable to every room without tearing up all the walls, my network is based on powerline taps which plug into the outlets in every room and distribute the internet signal over the house electrical wiring.
It looks like I'm going to have to hard wire ethernet cable to each room after all resulting in a bigger remodeling job than I originally planned.
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Could a power conditioner be cheaper?
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Danny,
You just brought up another potential issue. I have set up a wired home network throughout the house but since I couldn't run ethernet cable to every room without tearing up all the walls, my network is based on powerline taps which plug into the outlets in every room and distribute the internet signal over the house electrical wiring.
It looks like I'm going to have to hard wire ethernet cable to each room after all resulting in a bigger remodeling job than I originally planned.
Yep, those are supreme noise makers.
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Would running a dedicated 20 amp circuit to my listening room clean things up?
The dedicated circuit would come from a second breaker box which is in the garage and separate from the main breaker box (in the master bedroom) that is currently feeding power to the lights and outlets in the listening room. The lights and regular outlets would still be powered from the main box. Only the AV equipment would be powered from the new circuit.
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RFI is radio frequency interference. It picks it up through the air.
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Would running a dedicated 20 amp circuit to my listening room clean things up?
The dedicated circuit would come from a second breaker box which is in the garage and separate from the main breaker box (in the master bedroom) that is currently feeding power to the lights and outlets in the listening room. The lights and regular outlets would still be powered from the main box. Only the AV equipment would be powered from the new circuit.
It's hard to say that you'd get a big improvement. Service to the mini box may have a lot of noise generators, particularly on safety ground because it may be shared with main service routes. Loops get bigger on mini service too, since safety and neutral aren't tied.
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RFI is radio frequency interference. It picks it up through the air.
So the RFI is infiltrating Mike's in line filter because it's not shielded or grounded?
I personally don't spend a lot of money on cables for any part of my system. What I do do is purchase every cable including my Power cables, Speaker cables, digital cables and RCA interconnect cables dual shielded. I learned what non shielded and single shield cables can pick up when I ran regular RG6 in a house on Queen Anne hill in Seattle many years ago. The hill has 3 local TV towers on it and the ghosting on the TVs was incredible. So we reran all of the cables with RG6Q which is duel shielded and the problem was gone. We even had to make up our own short interconnect cables from the cable box to the TV because even a 3' run of RG6 was causing ghosting.
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It's hard to say that you'd get a big improvement. Service to the mini box may have a lot of noise generators, particularly on safety ground because it may be shared with main service routes. Loops get bigger on mini service too, since safety and neutral aren't tied.
Not sure what a mini service is. When we moved into this house it had 200 amp service at the meter but only a 100 amp service panel since the house is heated by natural gas. That panel was full so we had an electrician install a second 100 amp service panel in the garage. The (wiring for this panel goes back to the meter box, just like the original one.
Is this what you are talking about?
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So the RFI is infiltrating Mike's in line filter because it's not shielded or grounded?
I personally don't spend a lot of money on cables for any part of my system. What I do do is purchase every cable including my Power cables, Speaker cables, digital cables and RCA interconnect cables dual shielded. I learned what non shielded and single shield cables can pick up when I ran regular RG6 in a house on Queen Anne hill in Seattle many years ago. The hill has 3 local TV towers on it and the ghosting on the TVs was incredible. So we reran all of the cables with RG6Q which is duel shielded and the problem was gone. We even had to make up our own short interconnect cables from the cable box to the TV because even a 3' run of RG6 was causing ghosting.
I have compared a lot of shielded verses non-shielded cables and found across the board that non-shielded cables can sound a lot better even when using the same cable and just added or taking away the shield. However, not all applications for non-shielded cables work well. Some applications require the shielding.
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Try wrapping the crossover box with either copper foil or aluminum foil and ground it. It will at least lower the RFI getting to the internal connections.
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So the RFI is infiltrating Mike's in line filter because it's not shielded or grounded?
I personally don't spend a lot of money on cables for any part of my system. What I do do is purchase every cable including my Power cables, Speaker cables, digital cables and RCA interconnect cables dual shielded. I learned what non shielded and single shield cables can pick up when I ran regular RG6 in a house on Queen Anne hill in Seattle many years ago. The hill has 3 local TV towers on it and the ghosting on the TVs was incredible. So we reran all of the cables with RG6Q which is duel shielded and the problem was gone. We even had to make up our own short interconnect cables from the cable box to the TV because even a 3' run of RG6 was causing ghosting.
His filter is a weak spot, and it's possible for the parastic capacitance due to the construction to cause some radiation. A grounded box would reduce RF incoming, and there for less to radiate. It has to be grounded to the RCA's ground however or it'll still radiate.
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Try wrapping the crossover box with either copper foil or aluminum foil and ground it. It will at least lower the RFI getting to the internal connections.
No, for the reason I just stated it doesn't work. At least not for any benefit at the levels in a house.
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So the RFI is infiltrating Mike's in line filter because it's not shielded or grounded?
I personally don't spend a lot of money on cables for any part of my system. What I do do is purchase every cable including my Power cables, Speaker cables, digital cables and RCA interconnect cables dual shielded. I learned what non shielded and single shield cables can pick up when I ran regular RG6 in a house on Queen Anne hill in Seattle many years ago. The hill has 3 local TV towers on it and the ghosting on the TVs was incredible. So we reran all of the cables with RG6Q which is duel shielded and the problem was gone. We even had to make up our own short interconnect cables from the cable box to the TV because even a 3' run of RG6 was causing ghosting.
Greg,
I discovered the the problem was not in the inline filter like I originally thought. It turned out that it didn't matter whether the filter was in or out, whether I was using solid state or tube amplification, which DAC I used, whether the music was a digital file played from the computer or a CD played on the OPPO, or what interconnects were connected where. Sometimes there was static coming from the tweeters and other times there wasn't.
I was ready to pull the rest of my hair out, both of them :scratch:
Now that I am no longer waiting for coats of polyurethane to dry, I need to leave this problem alone until I finish the Wedgies and 3x8 Wedge bass units I'm building.
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Not sure what a mini service is. When we moved into this house it had 200 amp service at the meter but only a 100 amp service panel since the house is heated by natural gas. That panel was full so we had an electrician install a second 100 amp service panel in the garage. The (wiring for this panel goes back to the meter box, just like the original one.
Is this what you are talking about?
I'm just saying mini service in place of anything that isn't the main panel. Code is to tie neutral and safety at the main panel but never at subsequent panels. I'm not sure if it's per building or just per service location from power pole.
The issue with safety ground is that it's common to daisy chain it every which way to Sunday, so potentials, noise, etc can really become a problem for your secondary service panels, as it's possible to be down the line on the chain of noise from safety ground being connected all over prior. It still works as safety, but not for your objectives.
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His filter is a weak spot, and it's possible for the parastic capacitance due to the construction to cause some radiation. A grounded box would reduce RF incoming, and there for less to radiate. It has to be grounded to the RCA's ground however or it'll still radiate.
What do you mean by a ground box and how would I connect all the RCA's to it? Only my subwoofer cables have grounds attached.
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I'm just saying mini service in place of anything that isn't the main panel. Code is to tie neutral and safety at the main panel but never at subsequent panels. I'm not sure if it's per building or just per service location from power pole.
The issue with safety ground is that it's common to daisy chain it every which way to Sunday, so potentials, noise, etc can really become a problem for your secondary service panels, as it's possible to be down the line on the chain of noise from safety ground being connected all over prior. It still works as safety, but not for your objectives.
That is very likely here. The original house wiring follows no logical pattern as I learned it.
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Hal suggested safety grounding it, but that won't work. Grounding it to the RCA's would. Because all the grounds are connected on the jacks, I'd just remove the inside insulating ring. With a plastic box it won't do too much, but with a metal box it'll prevent incoming RF from radiating so much.
As practice I recommend doing the output jacks, which doesn't always matter but because the inductance is higher after the caps, I'd do it on those two. Then I'd stat ground to them from in and sub-out jacks.
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That is very likely here. The original house wiring follows no logical pattern as I learned it.
Power conditioner can help. There's a few ground isolating things that can help that aren't hard to implement or such. You can stop ground noise over RCA's following my little controversial device without the volume, in lab section. It could be in your new metal box. And then you could use Schurter DENO inductors on grounds for equipment/power distribution. That said, some filtration would help on the hot/neutral, because it's always better even in the most problem free houses. :D
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Battery powered electronics are starting to look worth investigating, aren't they?!
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:thumb:
Battery powered electronics are starting to look worth investigating, aren't they?!
Oh my, I'm just discovering :thumb:
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Battery powered electronics are starting to look worth investigating, aren't they?!
Personally, no.
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Personally, no.
I just made the switch and I'm extremely impressed.
Extremely black and dynamic, I'm only playing with about 10wpc, quite stunning actually
-jay
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My suggestion was to ground the shielding of crossover box to the RCA grounds. I did not say a safety ground.
As also suggested, the RCA cables should be well shielded to reduce the RFI if that is the cause.
The best way is to isolate the RFI source and disable it.
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I just made the switch and I'm extremely impressed.
Extremely black and dynamic, I'm only playing with about 10wpc, quite stunning actually
-jay
Jay,I'm very happy for you,I know what you mean
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Jay,I'm very happy for you,I know what you mean
Thanks Greg, me too :beer:
jay
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My suggestion was to ground the shielding of crossover box to the RCA grounds. I did not say a safety ground.
As also suggested, the RCA cables should be well shielded to reduce the RFI if that is the cause.
The best way is to isolate the RFI source and disable it.
Sorry, people usually mean safety ground when they just say ground but don't specify it within a return path.
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It's so confusing, 'ground' has so many meanings.
Just some of it's meanings:
Safety Ground/Protective Earth (Equipment Grounding Conductor)
Mother Earth (Grounding Electrode Conductor)
shield (chassis)
audio circuit common
signal common
DC supply common
equipotential point
While most of these are galvanically connected, each has a different task.
Or we could use the Henry Ott definition:
Ground - A path for current flow
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Curious what MLundy finds. I've run separate hard wired feed from main box to the audio room only. One single cryoed (plugged both grounded and ungrounded) line to a UberBuss feeding all components, to no avail. Two of Danny's filters lay waiting. I can insert one before a monoblock with no noise, insert the second, and hum returns. I'm beginning to think as most studios apparently, an entirely separate outside ground rod is suggested.
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Curious what MLundy finds. I've run separate hard wired feed from main box to the audio room only. One single cryoed (plugged both grounded and ungrounded) line to a UberBuss feeding all components, to no avail. Two of Danny's filters lay waiting. I can insert one before a monoblock with no noise, insert the second, and hum returns. I'm beginning to think as most studios apparently, an entirely separate outside ground rod is suggested.
tasar that really isn't enough information to understand what's going on.
Sure, studios do that. But they also have a special mixture they put the rod in for much lower impedance.