### Network

W

#### Wesley Hunt

Jan 1, 1970
0
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.

J

Jan 1, 1970
0

C

#### colin

Jan 1, 1970
0
Wesley Hunt said:
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.

Colin =^.^=

J

#### John Popelish

Jan 1, 1970
0
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.
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/

R

#### R. Steve Walz

Jan 1, 1970
0
John said:
Before the metric system of units was in widespread use in the U.S.

C

#### colin

Jan 1, 1970
0
John Popelish said:
Before the metric system of units was in widespread use in the U.S.
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/

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

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 =^.^=

W

#### Wesley Hunt

Jan 1, 1970
0
I need to replace some capacitors from the the crossover networks in a
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.

A

#### Al

Jan 1, 1970
0
Wesley Hunt said:
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.

I remember that once we called them "Mickey Mikes."

Al

J

#### John Popelish

Jan 1, 1970
0
R. Steve Walz said:
John Popelish wrote: (snip)

No, mmfd or MMFD.
(snip)

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).

G

#### Gary Lecomte

Jan 1, 1970
0
Wesley Hunt said:
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.

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

Just like the change from Cycles to Hertz.

D

#### Dave VanHorn

Jan 1, 1970
0
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.

R

#### R. Steve Walz

Jan 1, 1970
0
Wesley said:
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.
---------------------
milli would be a HELL of a low pass knee!!!
Like maybe between 0.1 & 1.0 Hz??

-Steve

C

#### colin

Jan 1, 1970
0
R. Steve Walz said:
---------------------
milli would be a HELL of a low pass knee!!!
Like maybe between 0.1 & 1.0 Hz??

-Steve

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

Colin =^.^=

W

#### Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
John Popelish said:
Before the metric system of units was in widespread use in the U.S.
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

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.

W

#### Watson A.Name - \Watt Sun, the Dark Remover\

Jan 1, 1970
0
Wesley Hunt said:
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.

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.

J

#### John Popelish

Jan 1, 1970
0
Watson A.Name - \"Watt Sun said:
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)

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

W

#### Wesley Hunt

Jan 1, 1970
0
The speakers are from the late 60's (KLH Model Twenty), and the cap is
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.

No, both red leads go to the same tweeter. I guess they were cheaper
than 8 uF caps.

B

#### BobGardner

Jan 1, 1970
0
Also, is the "50 VMP" that follows the capactitance
You bet. I think its VNP 'volts non polarized'... its isnt electrolytic... and
its got to handle the peak to peak voltage from the amp... 200V would be better
for a big amp (+-100V)

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