Is this really what you'd expect from an audio balun
The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...eld/dp/96K0889 |
Is this really what you'd expect from an audio balun
On Sun, 5 May 2013 09:44:40 -0700, "Bob F"
wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...eld/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? d |
Is this really what you'd expect from an audio balun
Don Pearce wrote:
On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...eld/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. |
Is this really what you'd expect from an audio balun
On Sun, 5 May 2013 10:26:13 -0700, "Bob F"
wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...eld/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. The downside of the transformer method is that lower bass response is usually somewhat compromised. d |
Is this really what you'd expect from an audio balun
In article , "Bob F"
wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...-rca-plug-rj45 -shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. It will stop ground loop problems for the range of frequencies where the transformers work. It's not clear what that is. Transformers have a limited working range of frequencies. The ones you posted have DC to MHz passthrough but limited common mode blocking. The other wiring of isolators blocks DC to MHz common mode but only passes through maybe 50Hz to 15 Khz; more or less depending on the quality. Isolators can do weird things to the impedance too. If this is pro-audio, the absolutely best fix is using balanced cables with balanced connectors. The audio quality will be superior to any other hack. -- I will not see posts from Google because I must filter them as spam |
Is this really what you'd expect from an audio balun
On Sun, 05 May 2013 23:04:35 -0700, isw wrote:
In article , (Don Pearce) wrote: On Sun, 5 May 2013 10:26:13 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ets/50-7725.pd f http://canada.newark.com/mcm-custom-...n-rca-plug-rj4 5-shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The downside of the transformer method is that lower bass response is usually somewhat compromised. For any sort of well-designed and properly terminated transformer, the lower 3dB point will be well below the frequency of any "musical note" you'll ever want to pass through it. So, no, bass response won't be compromised at all. Effects strat becoming apparent well before you hit the 3dB point. d |
Is this really what you'd expect from an audio balun
Don Pearce wrote:
On Sun, 05 May 2013 23:04:35 -0700, isw wrote: In article , (Don Pearce) wrote: On Sun, 5 May 2013 10:26:13 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ets/50-7725.pd f http://canada.newark.com/mcm-custom-...n-rca-plug-rj4 5-shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The downside of the transformer method is that lower bass response is usually somewhat compromised. For any sort of well-designed and properly terminated transformer, the lower 3dB point will be well below the frequency of any "musical note" you'll ever want to pass through it. So, no, bass response won't be compromised at all. Effects strat becoming apparent well before you hit the 3dB point. d |
Is this really what you'd expect from an audio balun
Don Pearce wrote:
On Sun, 05 May 2013 23:04:35 -0700, isw wrote: Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The windings being on a transformer arranged so that common mode noise cancels, and the signal doesn't? |
Is this really what you'd expect from an audio balun
I was going to get involved in this conversation, but have decided not to. All
I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un. |
Is this really what you'd expect from an audio balun
William Sommerwerck wrote:
I was going to get involved in this conversation, but have decided not to. All I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un. Which was exactly why I posted the question. At the least, there is a DC(/LF) path from one end to the other. |
Is this really what you'd expect from an audio balun
I was going to get involved in this conversation, but have decided
not to. All I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un). Which was exactly why I posted the question. At the least, there is a DC(/LF) path from one end to the other. Which seems to kill the whole reason for baluns, does it not? |
Is this really what you'd expect from an audio balun
On Mon, 6 May 2013 07:08:15 -0700, "Bob F"
wrote: Don Pearce wrote: On Sun, 05 May 2013 23:04:35 -0700, isw wrote: Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The windings being on a transformer arranged so that common mode noise cancels, and the signal doesn't? That's it. The windings are wound in the same direction on the two sides. That means that the forward and reverse signal currents on the two windings are always in opposite directions magnetically. So the signal doesn't see any net inductance. d |
Is this really what you'd expect from an audio balun
On Mon, 6 May 2013 07:24:26 -0700, "William Sommerwerck"
wrote: I was going to get involved in this conversation, but have decided not to. All I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un. Isolation is not implied in the function. As long as the signal on the output is of equal amplitude and opposite phase on the two ports, the job is done. This circuit satisfies that perfectly. d |
Is this really what you'd expect from an audio balun
On Mon, 6 May 2013 09:24:53 -0700, "William Sommerwerck"
wrote: I was going to get involved in this conversation, but have decided not to. All I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un). Which was exactly why I posted the question. At the least, there is a DC(/LF) path from one end to the other. Which seems to kill the whole reason for baluns, does it not? Nope, nothing to do with it - unless you require performance down to DC, which of course audio doesn't. d |
Is this really what you'd expect from an audio balun
Don Pearce wrote:
On Mon, 6 May 2013 07:08:15 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 05 May 2013 23:04:35 -0700, isw wrote: Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The windings being on a transformer arranged so that common mode noise cancels, and the signal doesn't? That's it. The windings are wound in the same direction on the two sides. That means that the forward and reverse signal currents on the two windings are always in opposite directions magnetically. So the signal doesn't see any net inductance. Is this design going to avoid ground loop problems? Those signals would just be on the one side, so would they be canceled? |
Is this really what you'd expect from an audio balun
On Mon, 6 May 2013 10:02:21 -0700, "Bob F"
wrote: Don Pearce wrote: On Mon, 6 May 2013 07:08:15 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 05 May 2013 23:04:35 -0700, isw wrote: Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. The windings being on a transformer arranged so that common mode noise cancels, and the signal doesn't? That's it. The windings are wound in the same direction on the two sides. That means that the forward and reverse signal currents on the two windings are always in opposite directions magnetically. So the signal doesn't see any net inductance. Is this design going to avoid ground loop problems? Those signals would just be on the one side, so would they be canceled? The ground loop is fixed by the inductance presenting a huge series impedance to the hum current, which only passes along the ground wire. There is no equal return current in the signal wire to cancel the inductance. d |
Is this really what you'd expect from an audio balun
Bob F wrote:
The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf This datasheet shows it is a VIDEO balun. Jon |
Is this really what you'd expect from an audio balun
In article ,
(Don Pearce) wrote: On Sun, 05 May 2013 23:04:35 -0700, isw wrote: In article , (Don Pearce) wrote: On Sun, 5 May 2013 10:26:13 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...Sheets/50-7725 .pd f http://canada.newark.com/mcm-custom-...alun-rca-plug- rj4 5-shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. I'd sure like to see (and measure) those inductors. My "spidey sense" (combined with the fact that they don't bother to spec the CMRR at 50 or 60 Hz.) tells me that they're probably way too physically small for that to be the case. The downside of the transformer method is that lower bass response is usually somewhat compromised. For any sort of well-designed and properly terminated transformer, the lower 3dB point will be well below the frequency of any "musical note" you'll ever want to pass through it. So, no, bass response won't be compromised at all. Effects strat becoming apparent well before you hit the 3dB point. Know anybody who can hear the difference *on actual program material* between flat to 5 Hz and -3dB at 5 Hz? Because the little thumb-sized not-at-all-special transformers I use in a homebrew groundloop killer have that measured characteristic. It's just not hard to find decent transformers for audio. Isaac |
Is this really what you'd expect from an audio balun
In article ,
"William Sommerwerck" wrote: I was going to get involved in this conversation, but have decided not to. All I know is that the schematics don't make much sense (primarily because there doesn't seem to be "proper" isolation between the bal and the un. The kind of sense the schematics make is economic -- to the seller. Isaac |
Is this really what you'd expect from an audio balun
On Mon, 06 May 2013 21:19:26 -0700, isw wrote:
In article , (Don Pearce) wrote: On Sun, 05 May 2013 23:04:35 -0700, isw wrote: In article , (Don Pearce) wrote: On Sun, 5 May 2013 10:26:13 -0700, "Bob F" wrote: Don Pearce wrote: On Sun, 5 May 2013 09:44:40 -0700, "Bob F" wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...Sheets/50-7725 .pd f http://canada.newark.com/mcm-custom-...alun-rca-plug- rj4 5-shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. I'd sure like to see (and measure) those inductors. My "spidey sense" (combined with the fact that they don't bother to spec the CMRR at 50 or 60 Hz.) tells me that they're probably way too physically small for that to be the case. Spidey sense is not always very useful. The downside of the transformer method is that lower bass response is usually somewhat compromised. For any sort of well-designed and properly terminated transformer, the lower 3dB point will be well below the frequency of any "musical note" you'll ever want to pass through it. So, no, bass response won't be compromised at all. Effects strat becoming apparent well before you hit the 3dB point. Know anybody who can hear the difference *on actual program material* between flat to 5 Hz and -3dB at 5 Hz? Because the little thumb-sized not-at-all-special transformers I use in a homebrew groundloop killer have that measured characteristic. It's just not hard to find decent transformers for audio. Isaac Construction of these transformers doesn't have to follow the normal rules. They don't need good linearity, so very high permeability ferrite can be used for the core in order to get a high inductance value. This is because the audio doesn't have to pass through the ferrite, it bypasses it. d |
Is this really what you'd expect from an audio balun
Construction of these transformers doesn't have to follow the normal
rules. They don't need good linearity, so very high permeability ferrite can be used for the core in order to get a high inductance value. This is because the audio doesn't have to pass through the ferrite, it bypasses it. ????????????????????????????????????????? I know of no transformer type in which the signal "passes through" the core material. |
Is this really what you'd expect from an audio balun
Bob F wrote: The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf That is a VIDEO Balun for 75 ohm unbalanced to 100 ohm balanced. It is not intended for audio. It is to use Cat5 wire for 75 Ohm video from security cameras. http://canada.newark.com/mcm-custom-...eld/dp/96K0889 Another link to the same part. |
Is this really what you'd expect from an audio balun
On Tue, 7 May 2013 03:46:38 -0700, "William Sommerwerck"
wrote: Construction of these transformers doesn't have to follow the normal rules. They don't need good linearity, so very high permeability ferrite can be used for the core in order to get a high inductance value. This is because the audio doesn't have to pass through the ferrite, it bypasses it. ????????????????????????????????????????? I know of no transformer type in which the signal "passes through" the core material. Nit-picking the terminology? In a transformer, the core is used to couple the signal from the primary to the secondary. In this sense the signal "passes through" it. In the series balun the only signal that interacts with the core is the unwanted common mode or single sided signal. This is generally of such a low value that it has no chance of causing sufficient field strength to cause non-linearity. d |
Is this really what you'd expect from an audio balun
Don Pearce wrote:
The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...Sheets/50-7725 .pd f http://canada.newark.com/mcm-custom-...alun-rca-plug- rj4 5-shield/dp/96K0889 Looks OK to me. It's configured as a series common mode stopper. What's the problem? Will this design eliminate ground loop problems? My concept of baluns was that they isolated the two ends by placing them on opposite windings of a transformer. I am no expert, which is why I asked. That is a different thing. You need a transformer to kill a ground loop entirely, but yes, provided there is enough inductance in the coils this will still make a good job of getting rid of hum from a ground loop. If there's enough inductance to attenuate 60 (or 50) Hz from the power line, why won't it do the same for similar frequencies in the desired signal? No, because of the way the windings are arranged their inductances cancel each other out for the audio signal, but not for the induced hum. I'd sure like to see (and measure) those inductors. My "spidey sense" (combined with the fact that they don't bother to spec the CMRR at 50 or 60 Hz.) tells me that they're probably way too physically small for that to be the case. Spidey sense is not always very useful. The downside of the transformer method is that lower bass response is usually somewhat compromised. For any sort of well-designed and properly terminated transformer, the lower 3dB point will be well below the frequency of any "musical note" you'll ever want to pass through it. So, no, bass response won't be compromised at all. Effects strat becoming apparent well before you hit the 3dB point. Know anybody who can hear the difference *on actual program material* between flat to 5 Hz and -3dB at 5 Hz? Because the little thumb-sized not-at-all-special transformers I use in a homebrew groundloop killer have that measured characteristic. It's just not hard to find decent transformers for audio. Isaac Construction of these transformers doesn't have to follow the normal rules. They don't need good linearity, so very high permeability ferrite can be used for the core in order to get a high inductance value. This is because the audio doesn't have to pass through the ferrite, it bypasses it. Doing a little research, I found the following page. It seems these baluns are "current mode" baluns. http://vk5ajl.com/projects/baluns.php |
Is this really what you'd expect from an audio balun
If these small transformers won't provide the characteristics you want/need,
you could look for an opto-isolation solution. -- Cheers, WB .............. "Bob F" wrote in message ... The schematic here seems completely wrong to me. http://www.mcmelectronics.com/conten...ts/50-7725.pdf http://canada.newark.com/mcm-custom-...eld/dp/96K0889 |
Is this really what you'd expect from an audio balun
"Don Pearce" wrote in message ... Effects strat becoming apparent well before you hit the 3dB point. d Yeah, but what about on a Gibson ? geoff |
Is this really what you'd expect from an audio balun
On Sat, 11 May 2013 01:17:11 +1200, "geoff"
wrote: "Don Pearce" wrote in message ... Effects strat becoming apparent well before you hit the 3dB point. d Yeah, but what about on a Gibson ? You talking about my Gisbon? d |
Is this really what you'd expect from an audio balun
"Don Pearce" wrote in message ... On Sat, 11 May 2013 01:17:11 +1200, "geoff" wrote: "Don Pearce" wrote in message ... Effects strat becoming apparent well before you hit the 3dB point. d Yeah, but what about on a Gibson ? You talking about my Gisbon? d As opposed to your 'strat' above .... ;-) geoff |
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