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#1
Posted to rec.audio.pro
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Where does the hum come from?
https://images-na.ssl-images-amazon....AC_SL1500_.jpg
Nothing is connected to that optical input DAC. No power. No signal. Nothing. Doesn't matter whether the antenna is connected or not. With the powered speaker (JBL LSR305, -10dVB, volume maximum) input disconnected, with its speaker wire dangling from its input, there is almost 0 sound from the speaker except an extremely faint wind sort of sound with my ear up against it. Humming begins when the speaker wire is plugged into the disconnected DAC. Why is that? The DAC isn't connected to anything else. Does it act as a receiver/antenna? The humming sound is low enough so it makes little difference, but it is noticeable. Thanks. |
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#2
Posted to rec.audio.pro
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Where does the hum come from?
On Tue, 9 Feb 2021 11:29:15 -0000 (UTC), John Doe
wrote: https://images-na.ssl-images-amazon....AC_SL1500_.jpg Nothing is connected to that optical input DAC. No power. No signal. Nothing. Doesn't matter whether the antenna is connected or not. With the powered speaker (JBL LSR305, -10dVB, volume maximum) input disconnected, with its speaker wire dangling from its input, there is almost 0 sound from the speaker except an extremely faint wind sort of sound with my ear up against it. Humming begins when the speaker wire is plugged into the disconnected DAC. Why is that? The DAC isn't connected to anything else. Does it act as a receiver/antenna? The humming sound is low enough so it makes little difference, but it is noticeable. Thanks. Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? d -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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#4
Posted to rec.audio.pro
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Where does the hum come from?
Why are you plugging a speaker wire into a DAC? Speakers are plugged
into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? I don't know where to start re-explaining. I thought that was verbose. I'd like to hear the answers to Don's questions. |
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#5
Posted to rec.audio.pro
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Where does the hum come from?
On 09/02/2021 15:40, Don Pearce wrote:
Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? The speaker mentioned has an amplifier built in, so will work when connected to a DAC which provides a line out connection. -- Tciao for Now! John. |
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#6
Posted to rec.audio.pro
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Where does the hum come from?
In article ,
John Doe says... Why is that? The DAC has single ended audio output on RCA sockets. The loudspeakers expect balanced audio input on XLR or TRS connetions. How are you converting from SE to balanced working? And what do you mean by "Speaker wire"? -- Ken |
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#7
Posted to rec.audio.pro
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Where does the hum come from?
Tobiah wrote:
Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? I don't know where to start re-explaining. I thought that was verbose. I'd like to hear the answers to Don's questions. It wasn't a question, it was an erroneous statement. Please properly introduce USENET authors and avoid deleting relevant text. |
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#8
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
Please don't do hard drugs and post at the same time...
-- Unsteadyken wrote: Path: eternal-september.org!reader02.eternal-september.org!weretis.net!feeder8.news.weretis.net !3.eu.feeder.erje.net!feeder.erje.net!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Unsteadyken Newsgroups: rec.audio.pro Subject: Where does the hum come from? Date: Tue, 9 Feb 2021 16:35:20 -0000 Organization: Home Lines: 16 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Trace: individual.net 5wTsT2pbVLnDEZbs1wsxcgrDoQoeWEzXLSC7TABYLssQFp+gOl Cancel-Lock: sha1:8LtwzCXQsaNm8dv75svlgnHFu6c= User-Agent: MicroPlanet-Gravity/3.0.4 Xref: reader02.eternal-september.org rec.audio.pro:91963 In article , John Doe says... Why is that? The DAC has single ended audio output on RCA sockets. The loudspeakers expect balanced audio input on XLR or TRS connetions. How are you converting from SE to balanced working? And what do you mean by "Speaker wire"? -- Ken |
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#9
Posted to rec.audio.pro
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Where does the hum come from?
On Tue, 9 Feb 2021 15:56:15 -0000 (UTC), John Doe
wrote: (Don Pearce) wrote: John Doe wrote: https://images-na.ssl-images-amazon....AC_SL1500_.jpg Nothing is connected to that optical input DAC. No power. No signal. Nothing. Doesn't matter whether the antenna is connected or not. With the powered speaker (JBL LSR305, -10dVB, volume maximum) input disconnected, with its speaker wire dangling from its input, there is almost 0 sound from the speaker except an extremely faint wind sort of sound with my ear up against it. Humming begins when the speaker wire is plugged into the disconnected DAC. Why is that? The DAC isn't connected to anything else. Does it act as a receiver/antenna? The humming sound is low enough so it makes little difference, but it is noticeable. Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? I don't know where to start re-explaining. I thought that was verbose. Verbose but not even slightly clear. It sounds like you may have a ground loop. If the speaker is grounded at the wall plug, and the DAC has its own wall plug ground, then a hum signal will be induced onto the signal wire by the current that flows along the ground of the audio cable. One of those grounds needs to go. The usual way is to keep the ground in the amplifier and disconnect all the others, so the only ground connection through the system is the one in the audio cable. But you need to understand what you are doing, because this can compromise safety. d -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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#10
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
Obviously "the DAC having its own wall plug ground" has absolutely nothing
to do with it SINCE I EXPLICITLY STATED THAT THE THING IS DISCONNECTED FROM EVERYTHING. Do you want to know what a "speaker wire" is, too, you illiterate moron? That's why I said to ask questions after the relevant part of what I said. You can't even count the number of fingers on your hand... -- (Don Pearce) wrote: Path: eternal-september.org!reader02.eternal-september.org!.POSTED!not-for-mail From: (Don Pearce) Newsgroups: rec.audio.pro Subject: Where does the hum come from? Date: Tue, 09 Feb 2021 16:51:21 GMT Organization: A noiseless patient Spider Lines: 48 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Injection-Info: reader02.eternal-september.org; posting-host="169e1115689465ad10ea04c0d672053b"; logging-data="13171"; "; posting-account="U2FsdGVkX186TrmBBPly5TE+TPrCW4aJeKT8SiETv j8=" Cancel-Lock: sha1:t38Yfe1D0hIbjNJEmMGFwGD+1mo= X-Antivirus-Status: Clean X-Newsreader: Forte Agent 1.5/32.451 X-Antivirus: Avast (VPS 210207-2, 07/02/2021), Outbound message Xref: reader02.eternal-september.org rec.audio.pro:91966 On Tue, 9 Feb 2021 15:56:15 -0000 (UTC), John Doe wrote: (Don Pearce) wrote: John Doe wrote: https://images-na.ssl-images-amazon....AC_SL1500_.jpg Nothing is connected to that optical input DAC. No power. No signal. Nothing. Doesn't matter whether the antenna is connected or not. With the powered speaker (JBL LSR305, -10dVB, volume maximum) input disconnected, with its speaker wire dangling from its input, there is almost 0 sound from the speaker except an extremely faint wind sort of sound with my ear up against it. Humming begins when the speaker wire is plugged into the disconnected DAC. Why is that? The DAC isn't connected to anything else. Does it act as a receiver/antenna? The humming sound is low enough so it makes little difference, but it is noticeable. Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? I don't know where to start re-explaining. I thought that was verbose. Verbose but not even slightly clear. It sounds like you may have a ground loop. If the speaker is grounded at the wall plug, and the DAC has its own wall plug ground, then a hum signal will be induced onto the signal wire by the current that flows along the ground of the audio cable. One of those grounds needs to go. The usual way is to keep the ground in the amplifier and disconnect all the others, so the only ground connection through the system is the one in the audio cable. But you need to understand what you are doing, because this can compromise safety. d -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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#11
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
On 09/02/2021 16:50, John Doe wrote:
Please don't do hard drugs and post at the same time... Those of us that are familiar with and use professional audio equipment have no trouble understanding Unsteady Ken's post. -- Tciao for Now! John. |
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#12
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
Also, top posting is deprecated on usenet.
On 09/02/2021 16:50, John Doe wrote: Please don't do hard drugs and post at the same time... -- Tciao for Now! John. |
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#13
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
Depreciated?
-- John Williamson wrote: Path: eternal-september.org!reader02.eternal-september.org!news.szaf.org!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: John Williamson Newsgroups: rec.audio.pro,free.spam Subject: Where does the hum come from? Date: Tue, 9 Feb 2021 17:24:47 +0000 Lines: 11 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Trace: individual.net 1c7TA6dnnNBVKBPfXAc/RAYt0CF+DPVp7q+alWHBI/7d6BN1Xd Cancel-Lock: sha1:x+WVMgdyeP2oZb0PffPSqLuwNHQ= User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:50.0) Gecko/20100101 Thunderbird/50.0 In-Reply-To: Content-Language: en-GB Xref: reader02.eternal-september.org rec.audio.pro:91969 free.spam:14177 Also, top posting is deprecated on usenet. On 09/02/2021 16:50, John Doe wrote: Please don't do hard drugs and post at the same time... -- Tciao for Now! John. |
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#14
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
On 09/02/2021 17:36, John Doe wrote:
Depreciated? Nope. Deprecated, depreciated means something entirely different. The definitions of both words are in all good dictionaries. Is English, be that British, Australian, American or some other dialect, not your first language? -- Tciao for Now! John. |
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#15
Posted to rec.audio.pro
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Where does the hum come from?
On Tuesday, February 9, 2021 at 10:23:42 AM UTC-8, John Williamson wrote:
On 09/02/2021 17:36, John Doe wrote: Depreciated? Nope. Deprecated, depreciated means something entirely different. The definitions of both words are in all good dictionaries. Is English, be that British, Australian, American or some other dialect, not your first language? -- Tciao for Now! John. Ah, yet another thread run amok! After reviewing all the useful information whilst trying to disregard the flames, I speculate that the output circuitry of the DAC presents some kind of "RLC" network that, indeed, makes the "speaker wire" into a somewhat tuned antenna that is in the faint AC environment we all experience. The JBL LSR305 at maximum gain boosts and outputs some of that as hum. Roy W. Rising "If you notice the *sound*, it's wrong!" |
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#16
Posted to rec.audio.pro
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Where does the hum come from?
On 10/02/2021 4:58 am, Tobiah wrote:
Why are you plugging a speaker wire into a DAC? Speakers are plugged into amplifiers. Are you saying that your system hums, and if you unplug the speaker the hum stops? I don't know where to start re-explaining. I thought that was verbose. I'd like to hear the answers to Don's questions. How about 'the LST305 is a powered speaker' ! If one didn't already know, or couldn't have guessed that from the context of the question (-10dBV into a passive speaker ?!!!), looking it up before asking such a dumb question normally unbecoming of Don, would have been appropriate. geoff |
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#17
Posted to rec.audio.pro
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Where does the hum come from?
Tobiah the Idiot Troll puked:
----------------------------- I'd like to hear the answers to Don's questions. ** There are no questions. The OP has no clue what he is talking about. Nor do you. ...... Phil |
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#18
Posted to rec.audio.pro
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Where does the hum come from?
John Dope wrote:
============== With the powered speaker (JBL LSR305, -10dVB, volume maximum) input disconnected, with its speaker wire dangling from its input, there is almost 0 sound from the speaker except an extremely faint wind sort of sound with my ear up against it. Humming begins when the speaker wire is plugged into the disconnected DAC. ** There is no "speaker wire" involved. What you have is an RCA signal lead - get the name right, you arrogant ****head. Some cheap RCA leads have little or no shielding, so try a good quality one and you problem may disappear. ....... phil |
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#19
Posted to rec.audio.pro
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Where does the hum come from?
I am -assuming- that the original poster is plugging a DAC that has a TRS
1/4" output into a powered speaker with a TRS input, using a proper TRS-TRS patch cable and that no speaker wire is involved. If unshielded speaker wire is used for line level connections, there will be a hum. Now.... a thing can hum for two reasons: either something is grounded in two places (causing a ground loop) or something is not grounded at all (causing something to be unshielded). We know the problem is not a ground loop because there is no connection to the DAC other than the speaker, and there is no connection to the speaker other than to the DAC and power. It's quite possible the DAC does not have a pin 1 connection to chassis and that therefore it is effectively unshielded until an input or power is connected to it. A multimeter will very quickly show if this is the case. If so, the hum will disappear when the system is configured for actual use. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#20
Posted to rec.audio.pro
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Where does the hum come from?
John Doe wrote:
Do you want to know what a "speaker wire" is, too, you illiterate moron? Speaker wire is unshielded zip cord or SO line. There is no speaker wire involved in your configuration. Your use of the word "speaker wire" has confused people into thinking that you actually have speaker wire somewhere. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#21
Posted to rec.audio.pro
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Where does the hum come from?
Scott Dorsey wrote:
================ If unshielded speaker wire is used for line level connections, there will be a hum. ** Certainly, but this can also happen with cheap RCA leads. I found this out when repairing a Fender tube amp with a faulty reverb. The connecting RCA leads were bad so I fitted a new pair that were the right length and had stubby plugs. The result was buzzing noise and loud squealing if you turned up the reverb gain pot. When cut open, the cable used was NOT co-axial !! The ground wires just ran alongside the core in a tight bunch providing no ES shielding. Soon as I fitted known, well shielded leads - all problems vanished. ...... Phil |
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#22
Posted to rec.audio.pro
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Where does the hum come from?
On 11/02/2021 12:53 pm, Scott Dorsey wrote:
I am -assuming- that the original poster is plugging a DAC that has a TRS 1/4" output into a powered speaker with a TRS input, using a proper TRS-TRS patch cable and that no speaker wire is involved. If unshielded speaker wire is used for line level connections, there will be a hum. Now.... a thing can hum for two reasons: either something is grounded in two places (causing a ground loop) or something is not grounded at all (causing something to be unshielded). We know the problem is not a ground loop because there is no connection to the DAC other than the speaker, and there is no connection to the speaker other than to the DAC and power. It's quite possible the DAC does not have a pin 1 connection to chassis and that therefore it is effectively unshielded until an input or power is connected to it. A multimeter will very quickly show if this is the case. If so, the hum will disappear when the system is configured for actual use. --scott Look at the picture in the OP link. RCA unbal outputs. geoff |
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#23
Posted to rec.audio.pro
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Where does the hum come from?
On 11/02/2021 12:55 pm, Scott Dorsey wrote:
John Doe wrote: Do you want to know what a "speaker wire" is, too, you illiterate moron? Speaker wire is unshielded zip cord or SO line. There is no speaker wire involved in your configuration. Your use of the word "speaker wire" has confused people into thinking that you actually have speaker wire somewhere. --scott LSR305 speakers are active. By 'speaker cable' he meant cable to the speaker. geoff |
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#24
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
On Tue, 9 Feb 2021 16:59:09 -0000 (UTC), John Doe
wrote: Obviously "the DAC having its own wall plug ground" has absolutely nothing to do with it SINCE I EXPLICITLY STATED THAT THE THING IS DISCONNECTED FROM EVERYTHING. Do you want to know what a "speaker wire" is, too, you illiterate moron? That's why I said to ask questions after the relevant part of what I said. You can't even count the number of fingers on your hand... Here's the problem. Your description is confused and confusing. You talk about speaker wire when you mean phono cable. And why are you talking about a DAC when it isn't plugged in? It is clearly not a part of the problem. Now let's try to sort out what you really mean. Are you saying that when your amplifier has an open circuit input, there is a low level hum? If so, that is absolutely fine. That's what they do. As long as it goes away when something is plugged in all is well. Get a phono plug and short the live to the ground. Now plug that in. Is the noise still there? d -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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#25
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
On 11/02/2021 09:58, Don Pearce wrote:
Here's the problem. Your description is confused and confusing. You talk about speaker wire when you mean phono cable. And why are you talking about a DAC when it isn't plugged in? It is clearly not a part of the problem. Did you look at the picture he posted? It shows a Bluetooth to analogue converter with an optical connection hiding round the back and a pair of phono sockets on the front, and as Bluetooth is digital, there must be a DAC inside it. What he claims is that the system is humming when the receiver is not connected to anything, is not powered up and is not plugged in to the wall. Now let's try to sort out what you really mean. Are you saying that when your amplifier has an open circuit input, there is a low level hum? If so, that is absolutely fine. That's what they do. As long as it goes away when something is plugged in all is well. Get a phono plug and short the live to the ground. Now plug that in. Is the noise still there? He is, as far as I can tell, claiming that when the input to the speakers is open circuit, there is only white or pink noise, and when he connects to the unpowered, unearthed, DAC he gets a hum. He is going from an unbalanced phono output to a balanced input to the active speakers. Unless he is forgetting about a connection somewhere, I can't see how anything can be coming out of the bluetooth receiver, which leaves capacitive coupling to the mains somewhere in the system as the only explanation. The other thing I'm wondering is why this is all being copied to the free.spam usenet group? -- Tciao for Now! John. |
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#26
Posted to rec.audio.pro,free.spam
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Where does the hum come from?
On Thu, 11 Feb 2021 11:02:07 +0000, John Williamson
wrote: On 11/02/2021 09:58, Don Pearce wrote: Here's the problem. Your description is confused and confusing. You talk about speaker wire when you mean phono cable. And why are you talking about a DAC when it isn't plugged in? It is clearly not a part of the problem. Did you look at the picture he posted? It shows a Bluetooth to analogue converter with an optical connection hiding round the back and a pair of phono sockets on the front, and as Bluetooth is digital, there must be a DAC inside it. What he claims is that the system is humming when the receiver is not connected to anything, is not powered up and is not plugged in to the wall. Now let's try to sort out what you really mean. Are you saying that when your amplifier has an open circuit input, there is a low level hum? If so, that is absolutely fine. That's what they do. As long as it goes away when something is plugged in all is well. Get a phono plug and short the live to the ground. Now plug that in. Is the noise still there? He is, as far as I can tell, claiming that when the input to the speakers is open circuit, there is only white or pink noise, and when he connects to the unpowered, unearthed, DAC he gets a hum. He is going from an unbalanced phono output to a balanced input to the active speakers. Unless he is forgetting about a connection somewhere, I can't see how anything can be coming out of the bluetooth receiver, which leaves capacitive coupling to the mains somewhere in the system as the only explanation. The other thing I'm wondering is why this is all being copied to the free.spam usenet group? When he shouted at me in his last post he said that everything was disconnected, I quote "Obviously "the DAC having its own wall plug ground" has absolutely nothing to do with it SINCE I EXPLICITLY STATED THAT THE THING IS DISCONNECTED FROM EVERYTHING." So the block diagram is kind of irrelevant. Presumably nothing is coming out of anything and it (I presume the speaker) is doing this all on its own. In other words he has a powered speaker that is not totally silent with an open circuit input. This is not news to me. d -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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#27
Posted to rec.audio.pro
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Where does the hum come from?
geoff wrote:
Look at the picture in the OP link. RCA unbal outputs. I have no graphics here. So RCA on one end, what is on the other end? If the RCA connector is run to pins 2 and 3 of an XLR on the other end with pin 1 lifted (as is a common and reasonable configuration), then the case of the powered speaker won't be connected to the case of the DAC until power is applied. So in that case the thing would hum in the configuration the original poster describes. But without knowing what the cable is, you don't know for sure. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#28
Posted to rec.audio.pro
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Where does the hum come from?
geoff wrote:
On 11/02/2021 12:55 pm, Scott Dorsey wrote: John Doe wrote: Do you want to know what a "speaker wire" is, too, you illiterate moron? Speaker wire is unshielded zip cord or SO line. There is no speaker wire involved in your configuration. Your use of the word "speaker wire" has confused people into thinking that you actually have speaker wire somewhere. LSR305 speakers are active. By 'speaker cable' he meant cable to the speaker. Yes, I gather that by "speaker wire" he meant a line level cable but this just added to the confusion. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#29
Posted to rec.audio.pro
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Where does the hum come from?
On 11/02/2021 11:29, Don Pearce wrote:
When he shouted at me in his last post he said that everything was disconnected, I quote "Obviously "the DAC having its own wall plug ground" has absolutely nothing to do with it SINCE I EXPLICITLY STATED THAT THE THING IS DISCONNECTED FROM EVERYTHING." So the block diagram is kind of irrelevant. Presumably nothing is coming out of anything and it (I presume the speaker) is doing this all on its own. In other words he has a powered speaker that is not totally silent with an open circuit input. This is not news to me. He claims that with an open circuit, he gets the normal white noise we all expect, but when he connects the speaker input to the output on the converter, he gets an audible hum. There is a pair of domestic standard (And quality) RCA phono connections on the converter, so the only thing I can suggest is that the shields on the two phono leads are making an earth loop connecting the two speaker inputs and the two phono sockets, which share an earth on the adaptor circuit board. The speakers will be sharing the safety earth of the whole system with each other. Going from a single ended output to a balanced input with no isolating transformer won't be helping. Either that or he thinks that turning the power off at the wall also disconnects the safety earth for the Bluetooth adaptor. I am using a similar Bluetooth adaptor to connect a car amplifier feeding a pair of speakers to the computer, and have no hum problem at all unless there is a poor connection between the amplifier and adaptor, when the jack plug has moved a fraction. Push it back in and peace is restored. Power for the amplifier is not connected to any earth, as it runs off 12 volts, and the Bluetooth adaptor is also fed by an isolated supply. The quality is good enough for an initial rough mix. -- Tciao for Now! John. |
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#30
Posted to rec.audio.pro
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Where does the hum come from?
In article ,
John Williamson says... Going from a single ended output to a balanced input with no isolating transformer won't be helping. I suspect the OPs "speaker wire" is probably an RCA cable with a mono 2 pole TRS adapter on the end. What connection that is making within the 3 pole TRS input is anybodies guess. -- Ken |
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#31
Posted to rec.audio.pro
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Where does the hum come from?
John Williamson wrote:
=================== He claims that with an open circuit, he gets the normal white noise we all expect, but when he connects the speaker input to the output on the converter, he gets an audible hum. There is a pair of domestic standard (And quality) RCA phono connections on the converter, so the only thing I can suggest is that the shields on the two phono leads are making an earth loop connecting the two speaker inputs and the two phono sockets, which share an earth on the adaptor circuit board. The speakers will be sharing the safety earth of the whole system with each other. Going from a single ended output to a balanced input with no isolating transformer won't be helping. ** That is the likely scenario. I did not expect balanced input, JBL self powered monitors with SMPSs to be other than class 2. https://jblpro.com/en-US/site_elements/lsr305-back **** poor design if this is true - cos it wont matter how you connect them. ...... Phil |
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#32
Posted to rec.audio.pro
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Where does the hum come from?
On 12/02/2021 2:02 am, Scott Dorsey wrote:
geoff wrote: Look at the picture in the OP link. RCA unbal outputs. I have no graphics here. So RCA on one end, what is on the other end? No graphics ? This *is* the 21st Century ! Or are you working on one of these ? ;- ) https://www.facebook.com/photo/?fbid...57424488371333 (for the insecure the link is to a picture on Facebook of a computer). If the RCA connector is run to pins 2 and 3 of an XLR on the other end with pin 1 lifted (as is a common and reasonable configuration), then the case of the powered speaker won't be connected to the case of the DAC until power is applied. So in that case the thing would hum in the configuration the original poster describes. But without knowing what the cable is, you don't know for sure. --scott Well can be sure it isn't a twin untwisted heavy-gauge speaker cable ! The LSR305 has bal (and equally unbal) jack and XLR inputs. At least mine have, and no hum even when connected via several intermediate devices to a PC, a mixture of bal and unbal. Would help to know the 'quality' and make-up/configuration of the RCA-to-whatever cable. geoff |
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#33
Posted to rec.audio.pro
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Where does the hum come from?
On 12/02/2021 5:05 am, Unsteadyken wrote:
In article , John Williamson says... Going from a single ended output to a balanced input with no isolating transformer won't be helping. I suspect the OPs "speaker wire" is probably an RCA cable with a mono 2 pole TRS adapter on the end. What connection that is making within the 3 pole TRS input is anybodies guess. Presumably pin 1 screen, pin 2 hot, and pin 3 bonded to pin 1. Maybe the XLR shell also bonded to pin 1. geoff |
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Posted to rec.audio.pro
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Where does the hum come from?
On 12/02/2021 10:15 am, geoff wrote:
On 12/02/2021 2:02 am, Scott Dorsey wrote: geoffÂ* wrote: Look at the picture in the OP link. RCA unbal outputs. I have no graphics here.Â* So RCA on one end, what is on the other end? No graphics ?Â* This *is* the 21st Century ! Or are you working on one of these ?Â* ;- ) https://www.facebook.com/photo/?fbid...57424488371333 (for the insecure the link is to a picture on Facebook of a computer). If the RCA connector is run to pins 2 and 3 of an XLR on the other end with pin 1 lifted (as is a common and reasonable configuration), then the case of the powered speaker won't be connected to the case of the DAC until power is applied.Â* So in that case the thing would hum in the configuration the original poster describes. But without knowing what the cable is, you don't know for sure. --scott Well can be sure it isn't a twin untwisted heavy-gauge speaker cable ! The LSR305 has bal (and equally unbal) jack and XLR inputs. At least mine have, and no hum even when connected via several intermediate devices to a PC, a mixture of bal and unbal. Would help to know the 'quality' and make-up/configuration of the RCA-to-whatever cable. geoff 'Slight' correction, mine are LSR705P. geoff |
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