MFD - does this mean millifarads or microfarads?

W

Wesley Hunt

Guest
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
 
microfarads.


Wesley Hunt wrote:

I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.
Click to expand...
 
"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
Click to expand...
probably millifarads, as m = milli or mega and its hardly likly to be mega,
microfards is usualy u.

Colin =^.^=
 
In article
<weNOsleSPAMy267-8799C6.06183012102004@comcast.dca.giganews.com>,
Wesley Hunt <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote:

I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be
mega,
microfards is usualy u.

I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
This is back when a "milliFarad" or 1000 uF would be a can 3-4" tall!

The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3 leads-
2 red, and a common black lead.
Click to expand...
I remember that once we called them "Mickey Mikes."

Al
 
chemelec posted:

<< Wesley Hunt <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:<weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com>...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.
Click to expand...

Back in the 50's & 60's, it was Very Common in Tube Schematics to see
MFD Representing Microfarads.
Actually it took me a long time to get used to uF.

Just like the change from Cycles to Hertz.
My 50s - 60s experiences were different.

In the Radio Amateur's Handbook (now the ARRL Handbook), ufd and uufd were
used. In other publications such as commercial equipment schematics, it was
common to see MFD, Mfd, ufd, mfd, uF, mmfd, mmf, etc. Even the Farad was often
in lower case (farad). I still have difficulty with nF, because I still don't
perceive a need for a term between uF and uuF or picoFarads. It's probably an
age thing.

I liked the deserved changeover to Hertz so it was easy to remember.

Don
 
Old: MFD New: uF Microfarads, F/1000000
Old: MMFD New: pF PicoFarads, F/1000000000000 (tiny!)

The british use nanofarads, as in 1000pF = 1nF

Anything like you described, is going to be in microfarads, and the present
day replacements will be a lot smaller.

--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR
 
"R. Steve Walz" <rstevew@armory.com> wrote in message
news:416C70B4.1FA9@armory.com...
Wesley Hunt wrote:
I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
This is back when a "milliFarad" or 1000 uF would be a can 3-4" tall!

The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3 leads-
2 red, and a common black lead.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
---------------------
MFD is microFarad.
milli would be a HELL of a low pass knee!!!
Like maybe between 0.1 & 1.0 Hz??

-Steve
Click to expand...
yes rather low, a 1 millifarad in series with an 8 ohms speaker would give
20hz rollof point... a sub sub woofer.

Colin =^.^=
 
"Watson A.Name - \"Watt Sun, the Dark Remover\"" wrote:
"John Popelish" <jpopelish@rica.net> wrote in message
news:416B3082.D4862471@rica.net...
(snip)
I have not seen the unit VMP but I suspect it is a form of voltage
rating. (voltage momentary peak, perhaps). You could replace it with

John, you missed it. You should've associated VMP with your following
sentence. It's not VMP, it's VNP, volts non-polarized - the usual
marking on electrolytic caps used in crossovers.
(snip)
Click to expand...

Excellent. I knew where I wanted to go, but not how to get there.

--
John Popelish
 
The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3
leads-
2 red, and a common black lead.

Apparently you have two tweeters? The common black lead should be from
the speaker terminals, and the two red leads should each go to one of
the tweeters. You should replace this cap with two capacitors, each
rated 4 microfarads, 50 Volts non-polarized.
Click to expand...
No, both red leads go to the same tweeter. I guess they were cheaper
than 8 uF caps.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
 
Wesley Hunt wrote:
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be
mega,
microfards is usualy u.

I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
This is back when a "milliFarad" or 1000 uF would be a can 3-4" tall!

The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3 leads-
2 red, and a common black lead.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
---------------------
Click to expand...
MFD is microFarad.
milli would be a HELL of a low pass knee!!!
Like maybe between 0.1 & 1.0 Hz??

-Steve
--
-Steve Walz rstevew@armory.com ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
 
"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:weNOsleSPAMy267-8799C6.06183012102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover
networks in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the
capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly
to be
mega,
microfards is usualy u.

I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
This is back when a "milliFarad" or 1000 uF would be a can 3-4"
tall!

The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3
leads-
2 red, and a common black lead.
Click to expand...
Apparently you have two tweeters? The common black lead should be from
the speaker terminals, and the two red leads should each go to one of
the tweeters. You should replace this cap with two capacitors, each
rated 4 microfarads, 50 Volts non-polarized.

--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
Click to expand...
 
colin wrote:
"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be mega,
microfards is usualy u.
Click to expand...
Before the metric system of units was in widespread use in the U.S.
mfd was the standard way to represent microfarad. Pico farads were
labeled mmf (micro micro farads). I doubt there any millifarad caps
in any cross over filter.

I have not seen the unit VMP but I suspect it is a form of voltage
rating. (voltage momentary peak, perhaps). You could replace it with
a 50 or more volt rated film capacitor (very large) or a nonpolarized
electrolytic (not as good or as long lasting but small and cheap).

This place sells lots of crossover parts:
http://www.partsexpress.com/

--
John Popelish
 
John Popelish wrote:
colin wrote:

"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be mega,
microfards is usualy u.

Before the metric system of units was in widespread use in the U.S.
mfd was the standard way to represent microfarad. Pico farads were
labeled mmf (micro micro farads).
------------------
Click to expand...
No, mmfd or MMFD.


I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
Click to expand...
This is back when a "milliFarad" or 1000 uF would be a can 3-4" tall!

-Steve
--
-Steve Walz rstevew@armory.com ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!! With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
 
"John Popelish" <jpopelish@rica.net> wrote in message
news:416B3082.D4862471@rica.net...
colin wrote:

"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message
news:weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be
mega,
microfards is usualy u.

Before the metric system of units was in widespread use in the U.S.
mfd was the standard way to represent microfarad. Pico farads were
labeled mmf (micro micro farads). I doubt there any millifarad caps
in any cross over filter.

I have not seen the unit VMP but I suspect it is a form of voltage
rating. (voltage momentary peak, perhaps). You could replace it with
a 50 or more volt rated film capacitor (very large) or a nonpolarized
electrolytic (not as good or as long lasting but small and cheap).

This place sells lots of crossover parts:
http://www.partsexpress.com/

--
John Popelish
Click to expand...
I agree this maybe so after all, i just looked through my BIG box of
capacitors >330uf some very old and they are all labeled with uF exept for
one wich is 220MF and its hardly big enough to be 0.22 F so it must be
mircofarad.

If it was a huge subwoofer crosover might it just be 1 milifarad ?

This just adds to the confusion in circuit schematics, and spice simualtors,
the number of times ive ended up with lots of 1 milliohm resistors in a
circuit wich required 1Mega ohms !!!

Colin =^.^=
 
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to be
mega,
microfards is usualy u.

I doubt there any millifarad caps
in any cross over filter.
John Popelish
-------------------------------
This is back when a "milliFarad" or 1000 uF would be a can 3-4" tall!
Click to expand...
The speakers are from the late 60's (KLH Model Twenty), and the cap is
about 2cm across and 5cm long. It is rated at "2 * 4 MFD", with 3 leads-
2 red, and a common black lead.
--
Wesley Hunt
weNOsleSPAMy267@yahNO_SPAMoo.com (remove "no spam" twice)
 
"R. Steve Walz" wrote:
John Popelish wrote:
(snip)
Before the metric system of units was in widespread use in the U.S.
mfd was the standard way to represent microfarad. Pico farads were
labeled mmf (micro micro farads).

No, mmfd or MMFD.
(snip)
Click to expand...

I am pretty sure that I have seen both designations on both parts and
schematics over the last 50 years.

But you are probably right that MMFD was more common than MMF (which
would have been confused with magneto-motive force).

--
John Popelish
 
Wesley Hunt <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message news:<weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com>...
I need to replace some capacitors from the the crossover networks in a
couple of speakers. They are rated in "MFD". Does that mean millifarads,
or microfarads? Also, is the "50 VMP" that follows the capactitance
rating sigificant? Thanks in advance for any help.
Click to expand...

Back in the 50's & 60's, it was Very Common in Tube Schematics to see
MFD Representing Microfarads.
Actually it took me a long time to get used to uF.

Just like the change from Cycles to Hertz.
 
"John Popelish" <jpopelish@rica.net> wrote in message
news:416B3082.D4862471@rica.net...
colin wrote:

"Wesley Hunt" <weNOsleSPAMy267@yahNO_SPAMoo.com> wrote in message

news:weNOsleSPAMy267-B7FC68.14042811102004@comcast.dca.giganews.com...
I need to replace some capacitors from the the crossover networks
in a
couple of speakers. They are rated in "MFD". Does that mean
millifarads,
or microfarads? Also, is the "50 VMP" that follows the
capactitance
rating sigificant? Thanks in advance for any help.

probably millifarads, as m = milli or mega and its hardly likly to
be mega,
microfards is usualy u.

Before the metric system of units was in widespread use in the U.S.
mfd was the standard way to represent microfarad. Pico farads were
labeled mmf (micro micro farads). I doubt there any millifarad caps
in any cross over filter.

I have not seen the unit VMP but I suspect it is a form of voltage
rating. (voltage momentary peak, perhaps). You could replace it with
Click to expand...
John, you missed it. You should've associated VMP with your following
sentence. It's not VMP, it's VNP, volts non-polarized - the usual
marking on electrolytic caps used in crossovers.

Putting a 'millifarad' capacitor in a speaker crossover would almost
guarantee that the tweeters would be damaged.

a 50 or more volt rated film capacitor (very large) or a nonpolarized
electrolytic (not as good or as long lasting but small and cheap).

This place sells lots of crossover parts:
http://www.partsexpress.com/

--
John Popelish
Click to expand...
 
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