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Is this really what you'd expect from an audio balun
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Bob F
May 5, 2013, 12:44:40 PM5/5/13
to
The schematic here seems completely wrong to me.
http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-rca-plug-rj45-shield/dp/96K0889
http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-rca-plug-rj45-shield/dp/96K0889
Don Pearce
May 5, 2013, 12:49:23 PM5/5/13
to
On Sun, 5 May 2013 09:44:40 -0700, "Bob F" <bobn...@gmail.com>
wrote:
>The schematic here seems completely wrong to me.
>http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
>
>http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-rca-plug-rj45-shield/dp/96K0889
>
Looks OK to me. It's configured as a series common mode stopper.
What's the problem?
d
wrote:
>The schematic here seems completely wrong to me.
>http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
>
>http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-rca-plug-rj45-shield/dp/96K0889
>
What's the problem?
d
Bob F
May 5, 2013, 1:26:13 PM5/5/13
to
they isolated the two ends by placing them on opposite windings of a
transformer. I am no expert, which is why I asked.
Don Pearce
May 5, 2013, 1:48:08 PM5/5/13
to
On Sun, 5 May 2013 10:26:13 -0700, "Bob F" <bobn...@gmail.com>
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
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
Kevin McMurtrie
May 5, 2013, 9:52:06 PM5/5/13
to
In article <km64h9$ocb$1...@dont-email.me>, "Bob F" <bobn...@gmail.com>
wrote:
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
wrote:
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
isw
May 6, 2013, 2:04:35 AM5/6/13
to
In article <51869ac2...@news.eternal-september.org>,
line, why won't it do the same for similar frequencies in the desired
signal?
> 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.
Isaac
sp...@spam.com (Don Pearce) wrote:
> On Sun, 5 May 2013 10:26:13 -0700, "Bob F" <bobn...@gmail.com>
> wrote:
>
> >Don Pearce wrote:
> >> On Sun, 5 May 2013 09:44:40 -0700, "Bob F" <bobn...@gmail.com>
> >> wrote:
> >>
> >>> The schematic here seems completely wrong to me.
> >>> http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pd
> >>> f
> >>>
> >>> http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-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
> On Sun, 5 May 2013 10:26:13 -0700, "Bob F" <bobn...@gmail.com>
> wrote:
>
> >Don Pearce wrote:
> >> On Sun, 5 May 2013 09:44:40 -0700, "Bob F" <bobn...@gmail.com>
> >> wrote:
> >>
> >>> The schematic here seems completely wrong to me.
> >>> http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pd
> >>> f
> >>>
> >>> http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-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.
line, why won't it do the same for similar frequencies in the desired
signal?
> The downside of the transformer method is that lower bass response is
> usually somewhat compromised.
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.
Isaac
Don Pearce
May 6, 2013, 2:59:16 AM5/6/13
to
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.
d
Bob F
May 6, 2013, 10:02:51 AM5/6/13
to
Bob F
May 6, 2013, 10:08:15 AM5/6/13
to
Don Pearce wrote:
> On Sun, 05 May 2013 23:04:35 -0700, isw <i...@witzend.com> 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,
> On Sun, 05 May 2013 23:04:35 -0700, isw <i...@witzend.com> 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.
and the signal doesn't?
William Sommerwerck
May 6, 2013, 10:24:26 AM5/6/13
to
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.
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.
Bob F
May 6, 2013, 10:45:47 AM5/6/13
to
path from one end to the other.
William Sommerwerck
May 6, 2013, 12:24:53 PM5/6/13
to
>> 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).
>> not to. All I know is that the schematics don't make much sense
>> (primarily because there doesn't seem to be "proper" isolation
> Which was exactly why I posted the question. At the least, there
> is a DC(/LF) path from one end to the other.
Don Pearce
May 6, 2013, 12:41:29 PM5/6/13
to
On Mon, 6 May 2013 07:08:15 -0700, "Bob F" <bobn...@gmail.com>
wrote:
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
wrote:
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
Don Pearce
May 6, 2013, 12:42:51 PM5/6/13
to
output is of equal amplitude and opposite phase on the two ports, the
job is done. This circuit satisfies that perfectly.
d
Don Pearce
May 6, 2013, 12:44:02 PM5/6/13
to
DC, which of course audio doesn't.
d
Bob F
May 6, 2013, 1:02:21 PM5/6/13
to
on the one side, so would they be canceled?
Don Pearce
May 6, 2013, 1:51:18 PM5/6/13
to
On Mon, 6 May 2013 10:02:21 -0700, "Bob F" <bobn...@gmail.com>
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
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
Jon Elson
May 6, 2013, 3:46:56 PM5/6/13
to
Bob F wrote:
> The schematic here seems completely wrong to me.
>
http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
>
>
This datasheet shows it is a VIDEO balun.
> The schematic here seems completely wrong to me.
>
http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
>
>
Jon
Don Pearce
May 6, 2013, 4:29:04 PM5/6/13
to
On Mon, 06 May 2013 14:46:56 -0500, Jon Elson <jme...@wustl.edu>
wrote:
So it needs a much wider bandwidth than just an audio one.
d
wrote:
d
Bob F
May 6, 2013, 4:29:33 PM5/6/13
to
claims to be"AUDIO BALUN, RCA PLUG-RJ45 SHIELD JACK". I guess Newark doesn't
have their act together.
Don Pearce
May 6, 2013, 4:39:20 PM5/6/13
to
On Mon, 6 May 2013 13:29:33 -0700, "Bob F" <bobn...@gmail.com>
wrote:
Just means you get some bonus performance - audio plus a load more.
d
wrote:
d
isw
May 7, 2013, 12:19:26 AM5/7/13
to
In article <5187545...@news.eternal-september.org>,
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
(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.
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
isw
May 7, 2013, 12:21:03 AM5/7/13
to
In article <km8e8b$r7m$1...@dont-email.me>,
The kind of sense the schematics make is economic -- to the seller.
Isaac
Isaac
isw
May 7, 2013, 12:29:46 AM5/7/13
to
In article <km93l0$2r8$1...@dont-email.me>, "Bob F" <bobn...@gmail.com>
wrote:
Look again. There are several devices on that page. The 50-7725 *is* for
audio.
Isaac
wrote:
audio.
Isaac
Don Pearce
May 7, 2013, 1:00:41 AM5/7/13
to
>> >> 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
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
William Sommerwerck
May 7, 2013, 6:46:38 AM5/7/13
to
> 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.
?????????????????????????????????????????
> 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.
Michael A. Terrell
May 7, 2013, 10:03:26 AM5/7/13
to
Bob F wrote:
>
> The schematic here seems completely wrong to me.
> http://www.mcmelectronics.com/content/ProductData/Spec%20Sheets/50-7725.pdf
is not intended for audio. It is to use Cat5 wire for 75 Ohm video from
security cameras.
>http://canada.newark.com/mcm-custom-audio/50-7725/audio-balun-rca-plug-rj45-shield/dp/96K0889
Another link to the same part.
Don Pearce
May 7, 2013, 12:11:06 PM5/7/13
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
Bob F
May 8, 2013, 1:05:56 AM5/8/13
to
"current mode" baluns.
http://vk5ajl.com/projects/baluns.php
Wild_Bill
May 8, 2013, 11:37:51 AM5/8/13
to
If these small transformers won't provide the characteristics you want/need,
you could look for an opto-isolation solution.
--
Cheers,
WB
.............
"Bob F" <bobn...@gmail.com> wrote in message
news:km623c$8uq$1...@dont-email.me...
you could look for an opto-isolation solution.
--
Cheers,
WB
.............
"Bob F" <bobn...@gmail.com> wrote in message
news:km623c$8uq$1...@dont-email.me...
geoff
May 10, 2013, 9:17:11 AM5/10/13
to
"Don Pearce" <sp...@spam.com> wrote in message
news:5187545...@news.eternal-september.org...
>
> Effects strat becoming apparent well before you hit the 3dB point.
>
> d
Yeah, but what about on a Gibson ?
> Effects strat becoming apparent well before you hit the 3dB point.
>
> d
geoff
geoff
May 10, 2013, 9:20:18 AM5/10/13
to
news:km93l0$2r8$1...@dont-email.me...
Just to fudge things further (not really, well not for us at least)
audio/video-over-cat5 industry calls the tx and rx 'baluns' !
geoff
audio/video-over-cat5 industry calls the tx and rx 'baluns' !
geoff
Don Pearce
May 10, 2013, 9:42:02 AM5/10/13
to
On Sat, 11 May 2013 01:17:11 +1200, "geoff" <ge...@nospampaf.co.nz>
wrote:
You talking about my Gisbon?
d
wrote:
d
geoff
May 10, 2013, 9:12:04 PM5/10/13
to
news:518cf906...@news.eternal-september.org...
As opposed to your 'strat' above ....
;-)
geoff
;-)
geoff
MrTallyman
May 12, 2013, 11:09:10 AM5/12/13
to
(where a ferrous "core" is involved) An air core type inductor probably
has different behavioral models for its operation (they do), but the
turns are counted within a toroidally wound structure, and on the inner
walls of other shapes of "core".
The turns count is exactly the number of turns that appears WITHIN the
core.
A transformer cannot work unless BOTH WINDINGS are WOUND AROUND and
THROUGH the CORE.
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