| Author |
Message |
Frank Vuotto
Guest
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 Posted:
Tue Nov 30, 2004 11:33 am Post subject:
Re: schematic and prints for akg 451 pad? |
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On Mon, 29 Nov 2004 21:40:01 -0800, "Richard Crowley"
<rcrowley7@xprt.net> wrote:
| Quote: |
All the pads I've seen are simply a single capacitor in
series with the signal path. No connection to the shell.
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As I recently mentioned, I have a 451 with problem threads. Works
with a pad and not without one. Today I disassembled a -10 db pad and
disconnect the cap, I took pictures and posted them, linked on the
bottom of my floobydust page.
http://www7.taosnet.com/f10/floobydust.htm
The 75pf clearly goes from the center post to the case.
Frank /~ http://newmex.com/f10
@/
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Phil Allison
Guest
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| Posted:
Wed Dec 01, 2004 12:05 am Post subject:
Re: schematic and prints for akg 451 pad? |
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"Scott Dorsey"
| Quote: |
Sure, but there are so many other things wrong with it that the issue is
fairly academic.
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** If Dorsey recommends something - then do the exact opposite.
.............. Phil |
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Phil Allison
Guest
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| Posted:
Wed Dec 01, 2004 12:05 am Post subject:
Re: schematic and prints for akg 451 pad? |
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"Scott Dorsey" = public menace
| Quote: |
Kurt Ballou <godcity@aol.com> wrote:
there seems to be a big shortage of -20db pads for 451's out there.
especially now that everyone is jumping on the lollipop bandwagon.
i'm suprised the BLUE hasn't started offering pads. i've been
searching for a couple of -20db pads for a couple of years now with no
luck, so i'm thinking of building a bunch myself. my dad is a
machinist who can take care of the metal work. i just need to figure
out what's going on inside. i think it's just a couple of resistors.
does anyone have a schematic, blue print, words of advice, one i could
borrow and reverse engineer, etc?
It's a capacitive shunt. This is why it affects the sound so
substantially.
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** There is no point in asking Dorsey *why* he believes this UTTER CRAP
to be true - that would only produce even more and worse crap from this
inexhaustible source of misinformation.
It's time we had a word to describe rabid, know nothing capacitor paranoids
like Dorsey .
How about " Dielectraphobic " ???
| Quote: | I really recommend avoiding the things as much as possible,
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** If Dorsey recommends something - then do the exact opposite !
| Quote: | but you can build one with a single NPO cap shunted across the capsule.
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** NPO caps are ceramics and are * LEAKY* and *MICROPHONIC* !!!!!!!
The only kind of caps that have low enough leakage to use for this job is
polystyrene.
A value of about 220 picofarads is needed for a -20 pad - connected
from centre pin to case.
| Quote: | If there is any way you can pad down on the output instead of the input
of the electronics, THERE you can use a resistive pad which will have
much less of a sonic effect.
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** If Dorsey recommends something - then do the exact opposite !
| Quote: | But if the mike electronics are clipping, you're stuck.
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** But you are * NOT * stuck with Dorsey's mad advice.
................ Phil |
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Scott Dorsey
Guest
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| Posted:
Wed Dec 01, 2004 12:06 am Post subject:
Re: schematic and prints for akg 451 pad? |
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In article <coih99$564$1@news1.chem.utoronto.ca>,
Rob Reedijk <reedijk@hera.med.utoronto.ca> wrote:
| Quote: | Richard Crowley <rcrowley7@xprt.net> wrote:
"Rob Reedijk" wrote ...
I would also think that it is difficult to create these things since
the body is what conducts the ground and it limits the type of pads
that can be designed. And no matter what, you will have trouble with
how the shunt resistor connects to the body in the pad.
All the pads I've seen are simply a single capacitor in
series with the signal path. No connection to the shell.
Like I said, I am not an EE! I have seen Frank Vuotto's web photos of
the pad which confirms what you said.
But you still have an extra coupling on the ground path. And this ground
path is a weakness in the design.
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Sure, but there are so many other things wrong with it that the issue is
fairly academic.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis." |
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Rob Reedijk
Guest
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| Posted:
Wed Dec 01, 2004 12:06 am Post subject:
Re: schematic and prints for akg 451 pad? |
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Richard Crowley <rcrowley7@xprt.net> wrote:
| Quote: | "Rob Reedijk" wrote ...
I would also think that it is difficult to create these things since
the body is what conducts the ground and it limits the type of pads
that can be designed. And no matter what, you will have trouble with
how the shunt resistor connects to the body in the pad.
All the pads I've seen are simply a single capacitor in
series with the signal path. No connection to the shell.
|
Like I said, I am not an EE! I have seen Frank Vuotto's web photos of
the pad which confirms what you said.
But you still have an extra coupling on the ground path. And this ground
path is a weakness in the design.
Rob R. |
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Peter Bell
Guest
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| Posted:
Wed Dec 01, 2004 12:06 am Post subject:
Re: schematic and prints for akg 451 pad? |
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The fine threads on the 451's are a continuing problem, we have
several what have damaged threads and are being heldn together with
tape.
Frank, I noticed in your annotation to the photos you marked the
centre piller has bein a switch of some sort. I thought it was jut
spring loaded to make a good contact.
Also in the recordings I make (classical music) it more a problem of
getting enought gain, and not too much noise, I've never used even a
-10dB pad.
Peter.
Frank Vuotto <deepthrob@hotmail.com> wrote in message news:<0d4oq0h7a8apv123dk9p37ak6lqjlar6ak@4ax.com>...
| Quote: |
As I recently mentioned, I have a 451 with problem threads. Works
with a pad and not without one. Today I disassembled a -10 db pad and
disconnect the cap, I took pictures and posted them, linked on the
bottom of my floobydust page.
http://www7.taosnet.com/f10/floobydust.htm
The 75pf clearly goes from the center post to the case.
Frank /~ http://newmex.com/f10
@/ |
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Frank Vuotto
Guest
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| Posted:
Wed Dec 01, 2004 12:06 am Post subject:
Re: schematic and prints for akg 451 pad? |
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On 30 Nov 2004 14:46:36 -0800, peter.bell@cisra.canon.com.au (Peter
Bell) wrote:
| Quote: | The fine threads on the 451's are a continuing problem, we have
several what have damaged threads and are being heldn together with
tape.
Frank, I noticed in your annotation to the photos you marked the
centre piller has bein a switch of some sort. I thought it was jut
spring loaded to make a good contact.
Also in the recordings I make (classical music) it more a problem of
getting enought gain, and not too much noise, I've never used even a
-10dB pad.
Peter.
Frank Vuotto <deepthrob@hotmail.com> wrote in message news:<0d4oq0h7a8apv123dk9p37ak6lqjlar6ak@4ax.com>...
As I recently mentioned, I have a 451 with problem threads. Works
with a pad and not without one. Today I disassembled a -10 db pad and
disconnect the cap, I took pictures and posted them, linked on the
bottom of my floobydust page.
http://www7.taosnet.com/f10/floobydust.htm
The 75pf clearly goes from the center post to the case.
Frank /~ http://newmex.com/f10
@/ |
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Frank Vuotto
Guest
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| Posted:
Wed Dec 01, 2004 6:01 am Post subject:
Re: schematic and prints for akg 451 pad? |
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Ooops, sorry about that blank post.
On 30 Nov 2004 14:46:36 -0800, peter.bell@cisra.canon.com.au (Peter
Bell) wrote:
| Quote: | The fine threads on the 451's are a continuing problem, we have
several what have damaged threads and are being heldn together with
tape.
|
Tape never worked for me, the mics made that awful noise they make
when there is a bad contact ( ok Scott, that's your cue). The threads
inside the body were completely gone (flat) on one side. The
non-pad-pad is working great.
| Quote: | Frank, I noticed in your annotation to the photos you marked the
centre piller has bein a switch of some sort. I thought it was jut
spring loaded to make a good contact.
|
No, it's not really a switch. The spring in the capsule pushes the
pillar into contact withe the 2 wires putting the cap across
(parallel) the capsule
| Quote: |
Also in the recordings I make (classical music) it more a problem of
getting enought gain, and not too much noise, I've never used even a
-10dB pad.
|
I may have to rig a switch for the pad cap because I sometimes use
these mics for drum overheads and they absolutly need to be padded
there. |
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Kurt Ballou
Guest
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| Posted:
Wed Dec 01, 2004 6:08 am Post subject:
Re: schematic and prints for akg 451 pad? |
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frank,
thanks so much for the pics. very helpful. any idea what cap value
for approx -20 or -30 db?
also, can you describe the switch? it is spring loaded? is that
really a switch, or is it just something that assures good contact?
thanks
kurt
Frank Vuotto <deepthrob@hotmail.com> wrote in message news:<0d4oq0h7a8apv123dk9p37ak6lqjlar6ak@4ax.com>...
| Quote: | On Mon, 29 Nov 2004 21:40:01 -0800, "Richard Crowley"
rcrowley7@xprt.net> wrote:
All the pads I've seen are simply a single capacitor in
series with the signal path. No connection to the shell.
As I recently mentioned, I have a 451 with problem threads. Works
with a pad and not without one. Today I disassembled a -10 db pad and
disconnect the cap, I took pictures and posted them, linked on the
bottom of my floobydust page.
http://www7.taosnet.com/f10/floobydust.htm
The 75pf clearly goes from the center post to the case.
Frank /~ http://newmex.com/f10
@/ |
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Phil Allison
Guest
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| Posted:
Fri Dec 03, 2004 6:18 am Post subject:
Re: schematic and prints for akg 451 pad? |
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"Kurt Ballou"
| Quote: |
ok. plans are moving along to fabricate some pads. anyone know how
to dismantle a 451?
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** No need to dismantle it for what you are doing.
Anyhow, IIRC there is a internal clip ring holding the XLR base in place.
Remove it and the whole guts slides out.
................ Phil |
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Kurt Ballou
Guest
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| Posted:
Fri Dec 03, 2004 6:18 am Post subject:
Re: schematic and prints for akg 451 pad? |
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ok. plans are moving along to fabricate some pads. anyone know how
to dismantle a 451? |
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jlupfer
Joined: 20 Mar 2007
Posts: 1
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| Posted:
Tue Mar 20, 2007 9:05 pm Post subject:
Re: schematic and prints for akg 451 pad? |
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| Kurt Ballou wrote: | ok. plans are moving along to fabricate some pads. anyone know how
to dismantle a 451? |
I realize this is 2 plus years ago, but I stumbled on it, because... I am looking for a 10 db pad for an AKG 451. Did you ever make any? |
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