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Re: OPA1642 SPICE Models
#dualopaalice
On Thu, Feb 6, 2025, 10:43 AM Mark Kahrs via <mark.kahrs=[email protected]> wrote:
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Re: OPA1642 SPICE Models
#dualopaalice
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:
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Re: Tsb 2590 mid side microphone?
#P48mems
You can do this, if you bring the capsules out separately and combine in Post you can create the figure 8. Keep them in the same plane facing opposite sides and as close?as possible. It will work. Jules On Thu, Feb 6, 2025 at 7:55?AM Muninn via <ninmiso=[email protected]> wrote:
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Best Regards, Jules Ryckebusch 214 399 0931 |
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Tsb 2590 mid side microphone?
#P48mems
Hi!
I've got 4 tsb2590 laying around, would love to use three of them for a mid side dual output mic.
I'm planning on use the p48 design as Jules has used in the ambi alice. How can I wire the two capsules used for sides?
Should I benefit in a different design with circuitry?
I've seen the mid side dual mic made from Jules, Tabitha, and I'm wondering if I could put the side capsules behind one another instead of side to side; is it a bad idea cause they got out of phase? I'm thinking of half a cm apart at best if put them like that.
I'm very inexperienced in building mics: I did just build the ambi alice in the past.? |
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Re: TSB2590 alternative?
Hi! I did built Jules ambialice and planned to build two but didn't sadly. Ive got four tsb2590 that I'm not using would you like to buy them or trade them with me? I'm located in Italy.
I would love to build a large diagram condenser mic and just have the donor body, if you have capsules or kits that you don't want I would gladly trade ;) |
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Re: OPA1642 SPICE Models
#dualopaalice
¿ªÔÆÌåÓýUsually 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 ¨¤ 02:31,
matthew@... a ¨¦crit?:
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Re: What is the role of the capacitor in Simpl48 circuit?
¿ªÔÆÌåÓýIt 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. Much less efficient than any active high-pass filter in the
preamp. Le 06/02/2025 ¨¤ 03:11, Adam Jo5eph via
groups.io a ¨¦crit?:
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Re: OPA1642 SPICE Models
#dualopaalice
On Wed, Feb 5, 2025 at 05:54 PM, Mark Kahrs wrote:
I literally took the .lib file provided by TI, which defines the SUBCKT and appended my SBCKT to it.
Yes. My intention was to account for all the pins with the parameters already defined in the .lib file. I am new to this, so I'm not sure that was the right way to go about it. I'm running with PSpice and LTSpice compatibility modes and it seems to be able to interpret everything correctly. Again, I'm very new to this. If it helps at all, the output looks like this: Note: Codel model file loading path is /home/matthew/workspace/Mic OPA/ Note: Compatibility modes selected: ps lt a Circuit: KiCad schematic Reducing trtol to 1 for xspice 'A' devices Doing analysis at TEMP = 27.000000 and TNOM = 27.000000 Using SPARSE 1.3 as Direct Linear Solver Note: Starting dynamic gmin stepping Warning: Dynamic gmin stepping failed Note: Starting true gmin stepping Warning: True gmin stepping failed Note: Starting source stepping Warning: source stepping failed Note: Transient op started Warning: singular matrix: ?check nodes xic1.xu1.n3294630 and c1:probe_int_n2#branch Warning: singular matrix: ?check nodes xic1.xu1.n2991579 and xic1.xu2.n2991581 Warning: singular matrix: ?check node xic1.xu1.n2991581 Warning: singular matrix: ?check nodes probe_int_probe_int_12v_c1_c1_2 and xic1.xu2.n2991579 Warning: singular matrix: ?check nodes xic1.xu1.n4619517 and xic1.xu2.n4619517 Warning: singular matrix: ?check nodes xic1.xu2.n3828449 and xic1.xu1.n2991581 Error: -4.91074e+150, -4.23671e+158 out of range for * in line bprobe_int_xic1power Error: -4.91074e+150, -4.23671e+158 out of range for * in line bprobe_int_xic1power Error: -4.91074e+150, -4.23671e+158 out of range for * in line bprobe_int_xic1power Error: -4.91074e+150, -4.23671e+158 out of range for * in line bprobe_int_xic1power Error: -4.91074e+150, -4.23671e+158 out of range for * ... ?
From there, it has a bunch of the same kind of errors, then some other lines and then eventually the unhelpful: doAnalyses: OP: ?Timestep too small; cause unrecorded. run simulation(s) aborted |
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Re: OPA1642 SPICE Models
#dualopaalice
Hold on, did you also define the SUBCKT for OPA164x???? I presume you did since this is what TI provides.? But I want to make sure. Basically, what you've done is to "call" two versions of the OPA164x subcircuit.? I used the word "call" in quotes since it's not a true procedure call. Further, do you know that this model works in Gnu SPICE?? (I am presuming that's what KiCAD uses). On Wed, Feb 5, 2025 at 8:42?PM matthew via <matthew=[email protected]> wrote:
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OPA1642 SPICE Models
#dualopaalice
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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Re: What is the role of the capacitor in Simpl48 circuit?
In order to work, it takes disconnecting one of the internal 6.81k resistors inside the preamp, or to isolate it DC-wise, which is exactly what teh capacitor does.
toggle quoted message
Show quoted text
Le 05/02/2025 ¨¤ 13:34, renthomsen via groups.io a ¨¦crit?:
One resistor P48 electret mic |
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Re: What is the role of the capacitor in Simpl48 circuit?
¿ªÔÆÌåÓý
Le 05/02/2025 ¨¤ 07:31, Adam Jo5eph via
groups.io a ¨¦crit?:
Tj=he role of the capacitor is to conduct AC signal whilst isolating DC. Not used, as in "not there" or as in "replaced with a short"? In the former case, very low signal, in the latter case, too low DC voltage on the capsule, so no signal. The capacitor acts as a high-pass filter, in conjunction with the mic preamp input impedance. Small cap-> no bass.
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Re: Microphone Output Impedance
¿ªÔÆÌåÓý
Le 04/02/2025 ¨¤ 00:06, Chris Caudle via
groups.io a ¨¦crit?:
This method is valid for unbalanced loads, but not for all types of balanced loads.. This is true only if the outputs are non-floating, which is the case of the typical Schoeps arrangement, or impedance-balanced circuits. Some circuits need to be measured differentially.
That is correct for a xfmr output, but electronically balanced circuits may not be suitale for having one of their legs grounded. That's why I recommended the OP to use a fully floating
measurement system.
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Re: Microphone Output Impedance
On Wed, Dec 18, 2024 at 08:02 AM, kandoit7 wrote:
In the case of measuring condenser microphone impedance using voltage drop Try this method shown in a Jensen Tranformer app-note:
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That will work for an active output microphone if you measure the impedance of pin 2 reference to pin 1, and separately pin 3 referenced to pin 1, and add the results together.
For a transformer output microphone you would use pin 3 as the reference pin for the signal generator, and connect the measurement resistor to pin 2. ?
-- Chris C |
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Re: Microphone Output Impedance
"Earthworks Homepage's M23R Spec :
OUTPUT IMPEDANCE ? ?65¦¸ balanced (between pins 2 & 3)" ?
That means exactly what it states, that the output signal is taken between pins 2 and 3, and the impedance of that signal is 65 Ohms.? Very likely not a transformer output, so an active output would have common mode impedances of 32.5 Ohms from pin 2 referenced to pin 1, and also from pin 3 referenced to pin 1, but for a transformer coupled output there would be no galvanic connection between either pin 2 or 3 and pin 1, so it would not make sense to discuss the impedance of pin 2 separately from pin 3, except in the context of parasitic capacitance and how that affects high frequency common mode impedance.
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-- Chris C
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Muninn
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