+4dBu to -10dBV pad schematic?

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I've got attenuation calculators and formulas up the wazoo, but does
anybody have a quick and easy schematic for a +4dBu to -10dbV pad using
stock resistor values?

TIA

--
Greg Glazier
Sound Editor
 
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retrotech@comcast.net wrote:
> I've got attenuation calculators and formulas up the wazoo, but does
> anybody have a quick and easy schematic for a +4dBu to -10dbV pad using
> stock resistor values?

Since the source and load impedance are part of the circuit, you may
not get as close as you want with standard values and two unknowns.
Also, since it's fairly common (though not a necessary condition) that
+4 dBu outputs are differential, how the output circuit is configured
can make a difference. The generic approach is to ground Pin 3 (or the
ring) but some output circuits don't like that, and some output
circuits will give you only half the voltage when you do that.

Best that you learn about these things and figure out for yourself what
you need, or if you want someone to design something for you, at least
post a link to the schematics of what you want to connect. How's that
for a tough assignment to keep you off our backs for a while? <g>

If you want to get in the ballpark, you might check out Rick Chinn's
article on pads at http://www.uneeda-audio.com/pads/
 
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Mike Rivers wrote:
>
> Best that you learn about these things and figure out for yourself what
> you need, or if you want someone to design something for you, at least
> post a link to the schematics of what you want to connect. How's that
> for a tough assignment to keep you off our backs for a while? <g>
>


Mike, why must you always patronize? I *do* know about these "things,"
I was only asking if someone had a real simple combo, like 1k and 10k.
FWIW, this is from a 600 ohm transformer out to a VCR. I don't really
care about tight tolerance or exact matching, this is for recording
VHS, not rocket design. :)

g2
 
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Jim Gregory wrote:
> Balanced or unbalanced?

Balanced to unbalanced... do you know of any -10dbV balanced devices?
I don't.

600 ohm transformer out to RCA VHS deck in. Tolerance WAY not critical.


g2
 
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retrot...@comcast.net wrote:

> Mike, why must you always patronize? I *do* know about these "things,"
> I was only asking if someone had a real simple combo, like 1k and 10k.

If you "know" about these things you wouldn't have to ask. You were
asking someone to design something that you should be able to design
yourself. I gave you a good resource, or you can use one of your
"calculators." Quit your bitching and be thankful that I'm helpful when
people actually are willing to take a little initiative.

> FWIW, this is from a 600 ohm transformer out to a VCR. I don't really
> care about tight tolerance or exact matching, this is for recording
> VHS, not rocket design. :)

Since it's coming from a transformer, you can safely ground the "low"
side. Get yourself a 10K pot and adjust it so that you get the right
level. That way, you won't even have to figure out what the ratio of +4
dBu to -10 dBV is, or even care whether the nominal input sensitivity
of the VCE is really -10 dBV (it probably isn't - that's a "semi pro
studio" standard level, not necessarily a "consumer gear" standard
level.)
 
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Mike Rivers wrote:
> retrot...@comcast.net wrote:
>
> > Mike, why must you always patronize? I *do* know about these "things,"
> > I was only asking if someone had a real simple combo, like 1k and 10k.
>
> If you "know" about these things you wouldn't have to ask. You were
> asking someone to design something that you should be able to design
> yourself. I gave you a good resource, or you can use one of your
> "calculators." Quit your bitching and be thankful that I'm helpful when
> people actually are willing to take a little initiative.

They really need to delete "pro" from the name of this group.
 
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Mike Rivers delicately wrote:

> Quit your bitching and be thankful that I'm helpful when
> people actually are willing to take a little initiative.

Thanks for being so helpful, Mike. You're a regular Mother Theresa. ;-)

Anyway, for the record, a 10K series and 3K6 shunt resistor will give
you a loss of 11.8 db (a voltage loss ratio of 3.88). This is for +4dbU
balanced (but tying low side to shield) to -10dbV.

Thanks.

g2
 
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retrotech@comcast.net wrote:

> Anyway, for the record, a 10K series and 3K6 shunt resistor will give
> you a loss of 11.8 db (a voltage loss ratio of 3.88). This is for +4dbU
> balanced (but tying low side to shield) to -10dbV.

See, I knew you could do it, and nobody even had to spoon feed you.
You're obviously a smart feller. Now build it. Neatly.
 
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retrotech wrote ...
> Mike Rivers wrote:
>> retrot...@comcast.net wrote:
>>
>> > Mike, why must you always patronize? I *do* know about these
>> > "things,"
>> > I was only asking if someone had a real simple combo, like 1k and
>> > 10k.
>>
>> If you "know" about these things you wouldn't have to ask. You were
>> asking someone to design something that you should be able to design
>> yourself. I gave you a good resource, or you can use one of your
>> "calculators." Quit your bitching and be thankful that I'm helpful
>> when
>> people actually are willing to take a little initiative.
>
> They really need to delete "pro" from the name of this group.

They will have to all agree on what it means, first. :)

I don't get your point. Mr. Rivers' response seemed
quite appropriate to me. OTOH, your initial question
was significantly lacking in important details which
only came out after goading from Mr. Rivers.
 
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Balanced or unbalanced?
+4dBU is just over 1.2Volt (U = with no impedance involved)
-10dBV is about a third of a Volt rms.
So you want to drop level down to to a quarter or -12dB voltage gain
(bridging assumed)
What source Z, what load Z, or is it a standard low-into-high route?
First try out this quicky L-pad [Schematic hardly needed.]
series 1k5, shunt 470 to 510, so total load is approx 2k, and use MO
resistors.

<retrotech@comcast.net> wrote in message
news:1125248383.532843.122780@o13g2000cwo.googlegroups.com...
> I've got attenuation calculators and formulas up the wazoo, but does
> anybody have a quick and easy schematic for a +4dBu to -10dbV pad using
> stock resistor values?
>
> TIA
>
> --
> Greg Glazier
> Sound Editor
>
 
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<retrotech@comcast.net> wrote:
>
>Mike Rivers wrote:
>>
>> Best that you learn about these things and figure out for yourself what
>> you need, or if you want someone to design something for you, at least
>> post a link to the schematics of what you want to connect. How's that
>> for a tough assignment to keep you off our backs for a while? <g>
>
>Mike, why must you always patronize? I *do* know about these "things,"
>I was only asking if someone had a real simple combo, like 1k and 10k.
>FWIW, this is from a 600 ohm transformer out to a VCR. I don't really
>care about tight tolerance or exact matching, this is for recording
>VHS, not rocket design. :)

You DO care then, because that's kind of a weird application. The
input impedance of the pad HAS to be 600 ohms, and the output impedance
is effectively infinite.

If you're trying the connection right now, and the output level is
much too high, put a 620 ohm bridge resistor across the output so
that the transformer stops ringing. See if that does not make your
levels more reasonable and the top end more pleasant too.

This kind of thing is exactly why Mike asked the question, since it
is quite possible you don't really need a pad at all, just a proper
termination resistor.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 
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Just asked u a normal scenario question.
In fact it's bal to unbal, but what Z is feeding the xformer primary?
Assuming nothing else is fed from the xformer sec, try my first lash-up
Otherwise try new values of 6k2 and 2k0 - 2k2. Suggest u construct 12dB pad
at receiving end.
Or you might try a 10k preset! hi end from source, wiper to destin, lo end
commoned to both devices, start at halfway and line up.

----- Original Message -----
From: <retrotech@comcast.net>
Newsgroups: rec.audio.pro
Sent: Sunday, August 28, 2005 9:30 PM
Subject: Re: +4dBu to -10dBV pad schematic?


>
> Jim Gregory wrote:
>> Balanced or unbalanced?
>
> Balanced to unbalanced... do you know of any -10dbV balanced devices?
> I don't.
>
> 600 ohm transformer out to RCA VHS deck in. Tolerance WAY not critical.
>
>
> g2
>
 
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On 28 Aug 2005 16:43:36 -0700, retrotech@comcast.net wrote:

>Anyway, for the record, a 10K series and 3K6 shunt resistor will give
>you a loss of 11.8 db (a voltage loss ratio of 3.88). This is for +4dbU
>balanced (but tying low side to shield) to -10dbV.

For the special case of negligible source impedance and
load impedance and a floating balanced to unbalanced
conversion, and incorrect otherwise.

FWIW, consumer electronics is *not* a -10dBV = 0VU
standard.

Since you apparently know these things, and know
how to make the 60 second calculation needed, what's
your beef?

Must be Sunday night,

Chris Hornbeck
"Fa yeung nin wa" -Wong KarWai
 
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retrotech@comcast.net wrote in
news:1125261023.080347.215710@g47g2000cwa.googlegroups.com:

>
> Jim Gregory wrote:
>> Balanced or unbalanced?
>
> Balanced to unbalanced... do you know of any -10dbV balanced
> devices? I don't.
>
Many of the JVC professional VCRs have a selectable +4/-10 inputs
and outputs, all balanced.The 5 BRs-811's in my edit suite are a
specific example.





--
Bob Quintal

PA is y I've altered my email address.
 
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retrotech@comcast.net wrote:

> Mike Rivers delicately wrote:
>
> > Quit your bitching and be thankful that I'm helpful when
> > people actually are willing to take a little initiative.
>
> Thanks for being so helpful, Mike. You're a regular Mother Theresa. ;-)
>
> Anyway, for the record, a 10K series and 3K6 shunt resistor will give
> you a loss of 11.8 db (a voltage loss ratio of 3.88). This is for +4dbU
> balanced (but tying low side to shield) to -10dbV.

Actually I make it -11.55dB unloaded. ( voltage ratio 3.77 )

And it's dB, dBu and dBV btw. Do please try and write your units correctly
! ;-)

Graham
 
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Setting the record straight:
600 ohm transformer secondary, TERMINATED, +4dBu out
Setup as unbalanced (tied low side to shield)
10K ohms series, 3K6 ohm shunt, per Rick Chinn's chart.
This gives me exactly what I need. If you want to quarrel with my
values used, take it up with Rick Chinn. ;-)
 
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retrotech@comcast.net wrote:

> 600 ohm transformer secondary, TERMINATED, +4dBu out
> Setup as unbalanced (tied low side to shield)
> 10K ohms series, 3K6 ohm shunt, per Rick Chinn's chart.
> This gives me exactly what I need. If you want to quarrel with my
> values used, take it up with Rick Chinn. ;-)

No arguments with your component values, if it gets you the results you
want. The only complaint is with your attitude. Take it somewhere else.
 
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<retrotech@comcast.net> wrote in message
news:1125261023.080347.215710@g47g2000cwa.googlegroups.com...
>
> Jim Gregory wrote:
> > Balanced or unbalanced?
>
> Balanced to unbalanced... do you know of any -10dbV balanced devices?
> I don't.

Yes, the CardDeluxe. Jumpered for -10dBV sensitivity, it's still a balanced
input.

Peace,
Paul
 
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<retrotech@comcast.net> wrote in message
>
> They really need to delete "pro" from the name of this group.


Why ? It's full of whores.

geoff
 

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