Re: What is the role of the capacitor in Simpl48 circuit?

This is what I have.

In this particular instance I'm doubling up the capsules but for a single capsule I'd have used a resistor of about 20k.

I think the resistor values should maybe be slightly higher as 9V at the capsule is pushing it a bit.

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Sorry to jump in on your post Adam but this info may be relevant.

IMG_20250210_164910873_MFNR~2.jpg

Re: What is the role of the capacitor in Simpl48 circuit?

#37168

开云体育

There's some confusion about what a "simplestp48" is. Can you post a schemo?

Le 09/02/2025 à 22:52, Fuzzyface via groups.io a écrit?:

Show quoted text

Yes, working ok with my standard Zoom F3.?

I'll check the setup tomorrow though as you have me doubting myself now....... just cautious as I can't find any references online anymore.

From memory the resistor value is different to that when using a capacitor. I'm using AOM5024 capsules.

Re: Tsb 2590 mid side microphone? #P48mems

#37167

Ricardo, I sent emails to your email address. Hope you received the two posts.

Regards,

zephyrmic

Re: What is the role of the capacitor in Simpl48 circuit?

#37166

Thank you Jerry,

I want to use PUI5024 capsule with Evo4 Audio interface, and the xlr output voltage is 47.6V.

I thought 8.5v output voltage is best for long term use/recording and maximum SN ratio, but I could be wrong...

I have experimented with different Simple48 output voltages (10v, 9.5v and 9v) and I did not see a serious change at voltages above 8.5v.

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Re: What is the role of the capacitor in Simpl48 circuit?

#37165

Yes, working ok with my standard Zoom F3.?

I'll check the setup tomorrow though as you have me doubting myself now....... just cautious as I can't find any references online anymore.

From memory the resistor value is different to that when using a capacitor. I'm using AOM5024 capsules.

Re: What is the role of the capacitor in Simpl48 circuit?

#37164

开云体育

Are you sure that SimplestP48 works with an unmodified preamp?

Le 09/02/2025 à 22:41, Fuzzyface via groups.io a écrit?:

Show quoted text

So what difference will be expected in the recording between a simpleP48 and a simplestP48 mic?

I've been using Martin's resistor only simplestP48 for a while and just assumed I would be missing any low frequency cut off.

I've looked for the YouTube clips for the simplestP48 but they are no longer there.

Re: What is the role of the capacitor in Simpl48 circuit?

#37163

So what difference will be expected in the recording between a simpleP48 and a simplestP48 mic?

I've been using Martin's resistor only simplestP48 for a while and just assumed I would be missing any low frequency cut off.

I've looked for the YouTube clips for the simplestP48 but they are no longer there.

Re: What is the role of the capacitor in Simpl48 circuit?

#37162

The gentle LF rolloff set by the choice of C value is not going to "cut off" anything. Please read up on single pole filters. If you need a hard cutoff below a specific frequency, the easiest place to get that is the highpass filter available on most field recorders, or by filtering in an audio editor afterwards.

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Re resistor values, the documentation of the SimpleP48 circuitry is superb, and covers all of this quite well. I did a little experimentation with my PUI AOM5024 capsules, but mostly to ensure that I wasn't exceeding the voltage and current ratings for the capsules. I ended up choosing 82k for resistor. I've built two simpleP48 pairs so far with AOM5024 capsules. In one pair, I used 4.7uf caps. In the other pair, which is now semipermanently installed outside, I used 2.2uf. There's still more than enough low-end there.?

Re: What is the role of the capacitor in Simpl48 circuit?

#37161

开云体育

Regarding "cut frequencies below 70Hz " see /g/MicBuilders/message/37143

Regarding "8.5v output voltage": I suppose you mean DC voltage across the capsule Why specifically 8.5?
DC voltage depends very much on the characteristics of the built-in FET. FET's have quite a large tolerance. Put in the same conditions, two capsules may show differences of 50%.
You don't mention the vboltage of the power source, which directly affects the voltage across the capsule.

Le 08/02/2025 à 02:33, Adam Jo5eph via groups.io a écrit?:

Show quoted text

Thank you so much everyone.
Is there any formula/equation to calculate resistor and capacitor values to getting cut frequencies below 70Hz and 8.5v output voltage?

By the way, I wan to use PUI5024 capsules.

Many thanks.

Bamboo Jecklin Disk prototype

#37160

I recently did some Jecklin Disk's experiments and uploaded pictures and a three-channel test recording to this folder.

At 02:18 of the test recording, a crow was kind enough to fly through the entire stereo image. :-)

The recording was not edited except that the volume was increased slightly.

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Microphones used: Micbuilder's SimpleP48 based on

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The three-channel Jecklin Disk stereo image recording method ?(one mic for the center...) is part of the OSIS 3-2-1 surround recording technique, which Jecklin used to record orchestras. In addition to other known recording methods he utilized two discs to record image and space.

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The three channel Jecklin Image Disk I experimented with in the field is a little larger (and looking like a scarecrow?! :-).?

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A number of original scripts by Jürg Jecklin on this topic are made available by the University of Music and Performing Arts Vienna under the following link (for private use and for study purposes...):

(all scripts are written in Jecklin’s native language...).

Re: Tsb 2590 mid side microphone? #P48mems

#37159

So here's my very simple M/S design from a couple decades ago:
/g/MicBuilders/files/Scott%20Helmke%27s%20stuff/newbiemic-1.jpg

It's not intuitive what's happening here with the side circuit, and it doesn't run off phantom power. The two side capsules form a "long tailed pair" circuit, which is often used for differential inputs. And I can't vouch for the technical specs, which I never measured. But it does work!

-Scott

Show quoted text

On 2/7/25 20:17, Arjay1949 wrote:

[Edited Message Follows]

I built an Mid/Side mic using 3 x electret capsules with intergral FETs (in my case they were Primo EM204s) using THIS SCHEMATIC <>
It works pretty well, but as you can see, there are quite a lot of components involved.
It's simpler to create a Mid/Side mic using electret capsules with external FETs. That way allows you to connect the two side capsules in series with? reverse polarity
(As illustrated on Jules Alice M/S mic <>? schematic )
I did an M/S mic based on that 'series wired' side capsule principle which is simpler (and cheaper!)? than creating an M/S mic using electret capsules with internal FETs.
( Some notes HERE <> )
But as you already have the capsules you want to use, fitted with internal FETs, then I think you'll need to build a version with circuitry based more around the EM204 type schematic.....

-- 
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy"  - Joe Henry

Re: Tsb 2590 mid side microphone? #P48mems

#37158
Edited

I built an Mid/Side mic using 3 x electret capsules with intergral FETs (in my case they were Primo EM204s) using

It works pretty well, but as you can see, there are quite a? lot of components involved.

It's simpler to create a Mid/Side mic using electret capsules with external FETs. That way allows you to connect the two side capsules in series with? reverse polarity

(As illustrated on Jules? ? schematic )

I did an M/S mic based on that 'series wired' side capsule principle which is simpler (and cheaper!)? than creating an M/S mic using electret capsules with internal FETs.

( Some notes ? )

But as you already have the capsules you want to use, fitted with internal FETs, then I think you'll need to build a version with circuitry based more around the EM204 type schematic.....

Re: OPA1642 SPICE Models #dualopaalice

#37157

Thanks for this info, everyone.

Re: What is the role of the capacitor in Simpl48 circuit?

#37156

Thank you so much everyone.
Is there any formula/equation to calculate resistor and capacitor values to getting cut frequencies below 70Hz and 8.5v output voltage?

By the way, I wan to use PUI5024 capsules.

Many thanks.

Re: Tsb 2590 mid side microphone? #P48mems

#37155

Have a look at Zap's S2PCM in his Files

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You feed each capsule to a separate FET and the Source of each FET to the bases of a Schoeps output stage

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The circuit needs updating; especially the overly complicated power arrangements.? I'm hoping Zap is still around and will do the honours.

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I'm actually playing with a LTspice sim of this which is why I want to get in touch with Zephyr (David Searle) who built a version which I tested in Zephyr.doc

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If Zap is OK, I'll post the recommended changes from my LTspice juju for a specialised Fig 8 with electret capsules for you.

Re: Tsb 2590 mid side microphone? #P48mems

#37154

Sorry Jules would it be possible to combine them inside the mic instead? In this way I have to use two mic preamps instead of three ;)

Re: What is the role of the capacitor in Simpl48 circuit?

#37153

开云体育

Le 06/02/2025 à 21:35, Richard Lee via groups.io a écrit?:

It sepends on the actual input impedance of the mic preamp.

For a typical 2kohm input impedance, the capacitor should be 1.15uF for 70Hz cut-off.
The actual response would be first-order, i.e. only 6dB/octave.

Much less efficient than any active high-pass filter in the preamp.

The actual effective resistance for LF roll-off is 1k5 (input Z of the preamp) + Zo (of the mike)? So a much smaller capacitor is needed for a 70Hz cut-off.

I would say slightly larger.
With Zin= 1.5k and Zo=150r, the capacitor must be 1.35uF for -3dB@70Hz

?

But Zo of the mike(s) varies a lot so, like Jerry, I wouldn't use this to set the LF limit but only to get rid of subsonic noise.

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Much of this is on page 2 of the latest version of SimpleP48.pdf? dtd. 29sep24

Re: What is the role of the capacitor in Simpl48 circuit?

#37152

That depends on your capsules impedance and the impedance of the following circuit. Trial and error is a fast way to discover what works for you. 2,2uF? Lower higher? It costs near to nothing to try this.

Show quoted text

Op do 6 feb 2025 03:11 schreef Adam Jo5eph via <adam.jo5eph=[email protected]>:

Got it, thank you much.

Then, what should be the capacitor value to cut off audio at frequencies lower than 70Hz?

Thanks again.

Re: What is the role of the capacitor in Simpl48 circuit?

#37151

It sepends on the actual input impedance of the mic preamp.

For a typical 2kohm input impedance, the capacitor should be 1.15uF for 70Hz cut-off.
The actual response would be first-order, i.e. only 6dB/octave.

Much less efficient than any active high-pass filter in the preamp.

The actual effective resistance for LF roll-off is 1k5 (input Z of the preamp) + Zo (of the mike)? So a much smaller capacitor is needed for a 70Hz cut-off.

?

But Zo of the mike(s) varies a lot so, like Jerry, I wouldn't use this to set the LF limit but only to get rid of subsonic noise.

?

Much of this is on page 2 of the latest version of SimpleP48.pdf? dtd. 29sep24

Re: OPA1642 SPICE Models #dualopaalice

#37150

On Thu, Feb 6, 2025, 10:43 AM Mark Kahrs via <mark.kahrs=[email protected]> wrote:

You're having convergence issues.? Here's a PSPICE document that covers possible problems.

On Thu, Feb 6, 2025 at 2:48?AM Jerry Lee Marcel via <jerryleemarcel=[email protected]> wrote:

Usually multiple package opamps are treated as individuals, each section being the typical +in, -in, out, V+ and V-. It does not represent the actual topology, but for simulation purposes, it does the jow fine.

Le 06/02/2025 à 02:31, matthew@... a écrit?:

I'm having fun with variations on the OPA Alice circuit and would like to be able to model using SPICE in KiCAD. I found the model on TI's website but it doesn't have the correct subcircuit for a 1642, which has 8 pins. I modified that lib with the following:

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```
* Added by matthew to model the 8-pin OPA1642AID
.SUBCKT OPA1642AID OUT_A IN-_A IN+_A VEE IN+_B IN-_B OUT_B VCC
XU1 IN+_A IN-_A VCC VEE OUT_A OPA164x
XU2 IN+_B IN-_B VCC VEE OUT_B OPA164x
.ENDS OPA1642AID
```
I then made sure that the pins match the symbol in my schematic, but when I tried to run an OP test, I got a bunch of warning and errors. Before I go down the path of trying to trouble-shoot all of this, does anyone have any experience with this who can offer any advice for modeling the OPA Alice circuit??

PS. I'm very new to electronics. I am a software engineer and have worked adjacent to and have even manage electrical engineers but this is not my area of expertise.

?

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PSpice-ConvergenceOnly-12.pdf