开云体育

ctrl + shift + ? for shortcuts
© 2025 开云体育
  1. MicBuilders
  2. Topics

Strange Simple P48 readings

 

A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

开云体育

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:

A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?

PXL_20240317_154934990.jpg

 

开云体育

But where is the capsule connected?

Le 17/03/2024 à 18:30, Adrian Hicks a écrit?:

I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

I haven't connected the capsule for fear of blowing it. I'm guessing herein lies my problem?


On Sun, Mar 17, 2024, 17:37 Jerry Lee Marcel <jerryleemarcel@...> wrote:

But where is the capsule connected?

Le 17/03/2024 à 18:30, Adrian Hicks a écrit?:
I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

开云体育

The capsule FET was integral to this. Otherwise you are measuring 48volts supplied by the 6.8K resistor (internal to the preamp) in series with the external P48 resistor. If you go to 1M you will be close to 48 volts ?at 6.8K you will be 24 volts. Make sense?
Best Regards,

Jules Ryckebusch?

On Mar 17, 2024, at 12:44, Adrian Hicks <mail@...> wrote:

?
I haven't connected the capsule for fear of blowing it. I'm guessing herein lies my problem?

On Sun, Mar 17, 2024, 17:37 Jerry Lee Marcel <jerryleemarcel@...> wrote:

But where is the capsule connected?

Le 17/03/2024 à 18:30, Adrian Hicks a écrit?:
I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

So, am I correct in thinking that this is basically a resistor divider? With the FET being one of the resistances in the system?
I'm not sure where you get the 48v and 24v results from.
Would I measure the resistance across the capsule in order to get the third value?
I'm just keen not to blow the caps. I've probably just opened a can of worms for myself by trying to optimise something that has worked for years, but I suppose it is all good learning.

On Sun, Mar 17, 2024, 18:10 Jules Ryckebusch <ryckebusch@...> wrote:
The capsule FET was integral to this. Otherwise you are measuring 48volts supplied by the 6.8K resistor (internal to the preamp) in series with the external P48 resistor. If you go to 1M you will be close to 48 volts ?at 6.8K you will be 24 volts. Make sense?
Best Regards,

Jules Ryckebusch?

On Mar 17, 2024, at 12:44, Adrian Hicks <mail@...> wrote:

?
I haven't connected the capsule for fear of blowing it. I'm guessing herein lies my problem?

On Sun, Mar 17, 2024, 17:37 Jerry Lee Marcel <jerryleemarcel@...> wrote:

But where is the capsule connected?

Le 17/03/2024 à 18:30, Adrian Hicks a écrit?:
I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?
 

Look at the DC path from Ground up through the external resistor, the FET then Pin3, the 6.8K resistor to the 48V. Without the capsule there is no circuit path. With the FET biased correctly, you have 5-7 volts across?it. Please see Ricardo's P48 document. It explains this. The only real thing to "optimize" is the external resistor?value specific to the internal FET of the Capsule. If you are using a PUI or Primo, that has already been optimized and is in the document.?image.png


On Sun, Mar 17, 2024 at 1:20?PM Adrian Hicks <mail@...> wrote:
So, am I correct in thinking that this is basically a resistor divider? With the FET being one of the resistances in the system?
I'm not sure where you get the 48v and 24v results from.
Would I measure the resistance across the capsule in order to get the third value?
I'm just keen not to blow the caps. I've probably just opened a can of worms for myself by trying to optimise something that has worked for years, but I suppose it is all good learning.

On Sun, Mar 17, 2024, 18:10 Jules Ryckebusch <ryckebusch@...> wrote:
The capsule FET was integral to this. Otherwise you are measuring 48volts supplied by the 6.8K resistor (internal to the preamp) in series with the external P48 resistor. If you go to 1M you will be close to 48 volts ?at 6.8K you will be 24 volts. Make sense?
Best Regards,

Jules Ryckebusch?

On Mar 17, 2024, at 12:44, Adrian Hicks <mail@...> wrote:

?
I haven't connected the capsule for fear of blowing it. I'm guessing herein lies my problem?

On Sun, Mar 17, 2024, 17:37 Jerry Lee Marcel <jerryleemarcel@...> wrote:

But where is the capsule connected?

Le 17/03/2024 à 18:30, Adrian Hicks a écrit?:
I don't know of an easy way of drawing a schematic on my phone but I did take a picture of the breadboard when I was fiddling at home earlier.?
RGB corresponds to 123
The DMM? is hooked up to the black probe on the leg of R1 and to the red wire on pin 3.
I hope that makes more sense?

On Sun, Mar 17, 2024, 17:21 Jerry Lee Marcel <jerryleemarcel@...> wrote:

Can you draw a schematic? Your description is hard to figure.

Where are you measuring teh voltage?

Le 17/03/2024 à 17:15, Adrian Hicks a écrit?:
A few years back I bought some EM172s to use with my Zoom H5.
More recently I've been lucky enough to pick up a lightly used MixPre6ii. I've been using the 172s with no problems, but thought I would go back and check the R value to make sure it was optimised for the MP.
I soldered an XLR to some header pins to make it easier to test things on a breadboard and was alarmed at the results.
Wiring is as follows:
Pin1 - resistor
Pin 2 - capacitor +ve
Pin three to what would be the +ve terminal on the mic
The -ve cap lead goes to the other resistor terminal.
I? played with values of R until going all the way to 1MOhm which gives a reading of 7-8v which fluctuates a lot.
As a side note with the negative lead of the cap connected to pin 2 V was ~34v so I sawpped it to be positive to pin 2
This doesn't seem to be even remotely close to the previous results in the PDF that Richard Lee created.?

?Am I missing something?



--
Best Regards,

Jules Ryckebusch

214 399 0931
 

On Sun, Mar 17, 2024 at 11:20 AM, Adrian Hicks wrote:
So, am I correct in thinking that this is basically a resistor divider? With the FET being one of the resistances in the system?
Sort of, but that's an incomplete explanation.

Would I measure the resistance across the capsule in order to get the third value?
NO. The FET in the capsule is part of an active circuit; you can't just "measure the resistance" with an ohmmeter across the pins of a capsule.

?I've probably just opened a can of worms for myself by trying to optimise something that has worked for years, but I suppose it is all good learning.
It's both. The simpleP48 document is both a foolproof recipe, and a pretty good explanation of how it works.

To get more into it, you could read up on .

1 - 9 of 9