On April 9, 2022 at 12:26:06 PM, henryspragens@... (henryspragens@...) wrote: I have a BRIGHT RED MARKED mic cable in my kit with 2 & 3 swapped
in case I have phase issues with a mic. (off topic) We built one of those recently ¡ª invaluable for sanity-checking mics for output polarity. It¡¯s also red. :) ¡ª matt.
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Mix the signals at the output.
Connect XLR pin 2 to pin 2 output from front side.
XLR pin 3 is switched between front side pin 3 for cardioid, rear side pin 2 for fig-8, and rear side pin 3 for omni. The addition / subtraction will take place in the mixer's differential input stage. The gotcha is most 3-position toggle switches don't have a contact for the 3rd position, so cardioid would leave pin 3 open. It could be done with a 5-pin to 3-pin adapter in a box with a SP3T rotary switch.
If you have 2 mixer inputs available, you could bring all 4 outputs out as designed, use the front (or rear) for cardioid; mix front and rear for omni; and use an XLR cable with pins 2 & 3 swapped on the rear and mix for fig-8. I have a BRIGHT RED MARKED mic cable in my kit with 2 & 3 swapped in case I have phase issues with a mic.
Jules of course has a multitrack recorder, and mixes in a DAW.
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Re: Hex inverter issue. Alice OPA
Hello The internal resistance of my meter appears to be 955kOhm so about 1MOhm.
Best regards Wiktor Molak
|
Re: Hex inverter issue. Alice OPA
If you have a 1M resistor, try this: ?measure a known voltage source 12V supply is good, even a 9V battery. Then put the 1M in series with the meter and measure again. ?You can calculate the internal resistance of the meter from the that. ?It¡¯s a simple resistor divider at that point? Best Regards,
Jules Ryckebusch?
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On Apr 9, 2022, at 12:10, LonDek <londekpolska@...> wrote:
? Hello, just a simple meter, it has few years now and I think I bought it for like 10 bucks.
Best regards Wiktor Molak
sob., 9 kwi 2022 o 18:35?Jules Ryckebusch < ryckebusch@...> napisa?(a): I would ask the same. The first asset of voltages all seem good.? The higher the stages the less current available thus the Meter can load it down.? I have fluke 87 that has a 20M input impedance.? I¡¯ll measure full set of voltages later today and post.? If you boaught the JLI board there is a test point that should be about 80VDV. That is before a final RC filter that has a 1M resistor in it. ? Best Regards,
Jules Ryckebusch? ?
What are you using to measure the voltage?
It is essential to use a high impedance meter (at least 10
Megohms)
Hello,
I am currently going through mental breakdown because of this
circuit! I have no idea why it's not working, I'm beginner with
electric circuits, simply following guides out there, schematics,
so incase you want to help me out, please keep that in mind.
Circuit is giving me only 32V on last diode, all my connections
are good, I've replaced diodes 2 times and IC itself 3 times,
trying 2 different models. I am currently using CD40100BE IC, same
that is in instructables guide, previously I've tried
MC14584BDR2G.
I have also measured voltages throughout whole circuit.
All voltages are referenced to ground.
I think the problem is that 7V here is detected as HIGH by IC and
being inverted back to 0V, but then why people didn't have
problems like this before?
And how can I solve it once for all.
Voltage from Alice zeners is 12.33V (previously on 200V range it
measured 12.2V, thats the reason why it's different in graphic)
Both XLR pins measure 20.9V
^^^^ All voltages here were measured with DC
setting on multimeter
Thanks for any advice
Wiktor Molak
|
Full balanced signal is soooo overated... Balanced impedance is
what matters.
But why not?
toggle quoted message
Show quoted text
There is also a possibility
of using one less opamp, by omitting U3 and making U4 a
full differential amp.
Actually, that's it!?
Removing U3 by making U4 a full differential means we can use that
spare OpAmp after the U4 mixing stage as an inverting amplifier to
produce the cold signal, thus giving us a full balanced signal!
|
Instinct tells me that trying to add switches around that kind of high impedance circuitry is asking for trouble! .. I may be proved wrong of course! :)
I'm not sure why you're not keen on the single sided output?? ... Many mics use that configuration.? My Rode NT1 does for example -- helps make it one of the lowest noise mics on the market!
By connecting the 'cold' side to ground, via the same size output resistor and capacitor, will keep the signal path 'balanced'.
Using the second op amp as a differential output certainly gives you another 6dB of signal, but it has little to do with the actual 'balance' of the system -- a similar (preferably identical) passive output is just as effective in that? regard.
The lower output signal from a single sided version does require more preamp gain, but most decent modern preamps should be able to provide that without any increase in measurable noise...
As I mentioned to Jerry in my reply to him, I did wonder if it might be possible to reconfigure component routing on the PCB, as? the amps are already configured as 2 x non-inverting buffers, and 2 x unity gain inverting amps?...
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On Sat, Apr 9, 2022 at 06:20 PM, <michaeljtbrooks@...> wrote:
Hi Arjay,
Looks interesting! Thanks for the idea. I'm still quite keen on a balanced signal output though.
How feasible is it to put switches on the high impedance side?
If so, how about this...
Still with four OpAmps, but we use a DPTT switch to change the rear capsule's OpAmp between non-inverting, null, inverting:
- Omni: Standard non-inverting
- Cardioid: + and - are connected together, resulting in null output
- Figure-8: Inverting. Positive input gets connected to virtual ground
We delay producing the cold signal until after mixing.
My two concerns about this approach are:?
1) Can you actually get away with putting switches on the high impedance input side? Or is that asking for trouble with spurious signal paths between the switch connections?
2) In cardioid mode, the Rear capsule OpAmp is still active, thus will be contributing some noise to the final signal.
I'm in the UK too. I bought Jules' PCBs via PCBway. I think it cost me about ?20 for 5 Dual OPA Alice plus 5 DC-DC Hex boards including shipping, which really wasn't too bad! I bought the components from a mixture of AliExpress and RS Components.
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Le 09/04/2022 ¨¤ 19:20, michaeljtbrooks@... a ¨¦crit?:
Hi Arjay,
Looks interesting! Thanks for the idea. I'm still quite keen on a balanced signal output though.
How feasible is it to put switches on the high impedance side?
You can't. Capsules need to see very high impedance, typically 1G (1 000 Megohm). You cannot operate a diff amp with such high values, noise would be enormous.
|
There is also a possibility of using one less opamp, by omitting U3 and making U4 a full differential amp.
Actually, that's it!? Removing U3 by making U4 a full differential means we can use that spare OpAmp after the U4 mixing stage as an inverting amplifier to produce the cold signal, thus giving us a full balanced signal!
|
On Sat, Apr 9, 2022 at 06:11 PM, Jerry Lee Marcel wrote:
There is also a possibility of using one less opamp, by omitting U3 and making U4 a full differential amp.
I did think about that Jerry, but decided that as the existing project PCB already has 2 x dual amps - each with one amp configured as a non inverting buffer and the other as an inverter - it might just be possible to reconfigure, using the majority of the existing components on the PCB?.....
|
Hi Arjay,
Looks interesting! Thanks for the idea. I'm still quite keen on a balanced signal output though.
How feasible is it to put switches on the high impedance side? If so, how about this...  Still with four OpAmps, but we use a DPTT switch to change the rear capsule's OpAmp between non-inverting, null, inverting:
- Omni: Standard non-inverting
- Cardioid: + and - are connected together, resulting in null output
- Figure-8: Inverting. Positive input gets connected to virtual ground
We delay producing the cold signal until after mixing. My two concerns about this approach are:? 1) Can you actually get away with putting switches on the high impedance input side? Or is that asking for trouble with spurious signal paths between the switch connections? 2) In cardioid mode, the Rear capsule OpAmp is still active, thus will be contributing some noise to the final signal. I'm in the UK too. I bought Jules' PCBs via PCBway. I think it cost me about ?20 for 5 Dual OPA Alice plus 5 DC-DC Hex boards including shipping, which really wasn't too bad! I bought the components from a mixture of AliExpress and RS Components.
|
There is also a possibility of using one less opamp, by omitting
U3 and making U4 a full differential amp.
Le 09/04/2022 ¨¤ 17:55, Arjay 1949 a
¨¦crit?:
toggle quoted message
Show quoted text
I live in the UK, so the shipping costs for Jules' PCBs are way
too expensive for me!......
So I tried out my own experiments with the OPA1642 and OPA 1641
amps that Jules recommended.... Some project notes here: ?
You can see from those notes that I opted for a single sided
output, and a passively balanced second output to help maintain
CMRR.
Taking that approach I can see that you could achieve what you
want with 4 op-amps ( 2 x OPA1642). Any more than 4 and you are
probably going to start running out of phantom power?
I've attached a concept schematic of how I might approach your
idea for multi-pattern??
It would require a 3 position? - (centre off)? - single pole
switch.?
Top position: Omni? ---? centre position: Cardioid? --- lower
position: Figure of 8?
The single sided output idea takes a simpler approach, which would
reduce the number of op-amps required, and simplify the switching
for the task you have in mind.
I'm not sure Jules' PCBs would be much help here though ? ...
Anyway, just a thought.... :)
On Sat, Apr 9, 2022 at 02:26 PM, <michaeljtbrooks@...>
wrote:
Hi All,?
(Mainly FAO Jules, but I thought this discussion would be
useful to a others)
What would be the best way of introducing a pattern switch to
the rather than extracting two separate
signals from the mic?
I totally understand Jules' reasons for pulling two signals
from the mic where it's much easier to switch pattern on a
desk than to fumble around with the mic. However I'm lacking a
polarity inverter (?) in my mixing desk so want to be able to
do it in-mic.
I've got this CK12 style edge-terminated capsule from
AliExpress:?
I'm using the Dual OPA Alice circuit with DC-DC hex inverter
multiplier to provide capsule bias. I'm using Jules' PCBs (, ) from PCB Way
I'd quite like to switch between cardioid, omni and
figure-of-8, but without having to generate a negative bias
voltage for the rear capsule. Given that there are two dual
OPAs in the circuit outputting a fully balanced signal, surely
there's a way to mix them in the mic by swapping the outputs
of one of them when needed?
i.e. using a double-pole triple-throw switch on the rear
capsule OPA balanced output
- Cardioid: rear capsule OPA outputs not connected
- Omni: rear capsule OPA outputs connected to front capsule
OPA outputs in phase?
- Figure-of-8: rear capsule OPA outputs connected to front
capsule OPA outputs out of phase (swapped over)
Would that work?
Could I get away with a passive resistor-based mixer for the
front + rear signals? Or am I going to be looking at adding
another op-amp here (do we even have any more current headroom
from phantom power)?
Cheers,
Mike
?
?
|
Re: Hex inverter issue. Alice OPA
Hello, just a simple meter, it has few years now and I think I bought it for like 10 bucks.
Best regards Wiktor Molak
sob., 9 kwi 2022 o 18:35?Jules Ryckebusch < ryckebusch@...> napisa?(a):
I would ask the same. The first asset of voltages all seem good.? The higher the stages the less current available thus the Meter can load it down.? I have fluke 87 that has a 20M input impedance.? I¡¯ll measure full set of voltages later today and post.? If you boaught the JLI board there is a test point that should be about 80VDV. That is before a final RC filter that has a 1M resistor in it. ? Best Regards,
Jules Ryckebusch? ?
What are you using to measure the voltage?
It is essential to use a high impedance meter (at least 10
Megohms)
Hello,
I am currently going through mental breakdown because of this
circuit! I have no idea why it's not working, I'm beginner with
electric circuits, simply following guides out there, schematics,
so incase you want to help me out, please keep that in mind.
Circuit is giving me only 32V on last diode, all my connections
are good, I've replaced diodes 2 times and IC itself 3 times,
trying 2 different models. I am currently using CD40100BE IC, same
that is in instructables guide, previously I've tried
MC14584BDR2G.
I have also measured voltages throughout whole circuit.
All voltages are referenced to ground.
I think the problem is that 7V here is detected as HIGH by IC and
being inverted back to 0V, but then why people didn't have
problems like this before?
And how can I solve it once for all.
Voltage from Alice zeners is 12.33V (previously on 200V range it
measured 12.2V, thats the reason why it's different in graphic)
Both XLR pins measure 20.9V
^^^^ All voltages here were measured with DC
setting on multimeter
Thanks for any advice
Wiktor Molak
|
Re: Hex inverter issue. Alice OPA
I would ask the same. The first asset of voltages all seem good. ?The higher the stages the less current available thus the Meter can load it down. ?I have fluke 87 that has a 20M input impedance. ?I¡¯ll measure full set of voltages later today and post. ?If you boaught the JLI board there is a test point that should be about 80VDV. That is before a final RC filter that has a 1M resistor in it. ? Best Regards,
Jules Ryckebusch?
toggle quoted message
Show quoted text
On Apr 9, 2022, at 10:39, Jerry Lee Marcel <jerryleemarcel@...> wrote:
?
What are you using to measure the voltage?
It is essential to use a high impedance meter (at least 10
Megohms)
Hello,
I am currently going through mental breakdown because of this
circuit! I have no idea why it's not working, I'm beginner with
electric circuits, simply following guides out there, schematics,
so incase you want to help me out, please keep that in mind.
Circuit is giving me only 32V on last diode, all my connections
are good, I've replaced diodes 2 times and IC itself 3 times,
trying 2 different models. I am currently using CD40100BE IC, same
that is in instructables guide, previously I've tried
MC14584BDR2G.
I have also measured voltages throughout whole circuit.
All voltages are referenced to ground.
I think the problem is that 7V here is detected as HIGH by IC and
being inverted back to 0V, but then why people didn't have
problems like this before?
And how can I solve it once for all.
Voltage from Alice zeners is 12.33V (previously on 200V range it
measured 12.2V, thats the reason why it's different in graphic)
Both XLR pins measure 20.9V
^^^^ All voltages here were measured with DC
setting on multimeter
Thanks for any advice
Wiktor Molak
|
I live in the UK, so the shipping costs for Jules' PCBs are way too expensive for me!...... So I tried out my own experiments with the OPA1642 and OPA 1641 amps that Jules recommended.... Some project notes here: ? You can see from those notes that I opted for a single sided output, and a passively balanced second output to help maintain CMRR. Taking that approach I can see that you could achieve what you want with 4 op-amps ( 2 x OPA1642). Any more than 4 and you are probably going to start running out of phantom power? I've attached a concept schematic of how I might approach your idea for multi-pattern?? It would require a 3 position? - (centre off)? - single pole switch.? Top position: Omni? ---? centre position: Cardioid? --- lower position: Figure of 8? The single sided output idea takes a simpler approach, which would reduce the number of op-amps required, and simplify the switching for the task you have in mind. I'm not sure Jules' PCBs would be much help here though ? ... Anyway, just a thought.... :) 
On Sat, Apr 9, 2022 at 02:26 PM, <michaeljtbrooks@...> wrote:
Hi All,?
(Mainly FAO Jules, but I thought this discussion would be useful to a others)
What would be the best way of introducing a pattern switch to the rather than extracting two separate signals from the mic?
I totally understand Jules' reasons for pulling two signals from the mic where it's much easier to switch pattern on a desk than to fumble around with the mic. However I'm lacking a polarity inverter (?) in my mixing desk so want to be able to do it in-mic.
I've got this CK12 style edge-terminated capsule from AliExpress:?
I'm using the Dual OPA Alice circuit with DC-DC hex inverter multiplier to provide capsule bias. I'm using Jules' PCBs (, ) from PCB Way
I'd quite like to switch between cardioid, omni and figure-of-8, but without having to generate a negative bias voltage for the rear capsule. Given that there are two dual OPAs in the circuit outputting a fully balanced signal, surely there's a way to mix them in the mic by swapping the outputs of one of them when needed?
i.e. using a double-pole triple-throw switch on the rear capsule OPA balanced output
- Cardioid: rear capsule OPA outputs not connected
- Omni: rear capsule OPA outputs connected to front capsule OPA outputs in phase?
- Figure-of-8: rear capsule OPA outputs connected to front capsule OPA outputs out of phase (swapped over)
Would that work?
Could I get away with a passive resistor-based mixer for the front + rear signals? Or am I going to be looking at adding another op-amp here (do we even have any more current headroom from phantom power)?
Cheers,
Mike
?
?
|
Re: Hex inverter issue. Alice OPA
What are you using to measure the voltage?
It is essential to use a high impedance meter (at least 10
Megohms)
toggle quoted message
Show quoted text
Hello,
I am currently going through mental breakdown because of this
circuit! I have no idea why it's not working, I'm beginner with
electric circuits, simply following guides out there, schematics,
so incase you want to help me out, please keep that in mind.
Circuit is giving me only 32V on last diode, all my connections
are good, I've replaced diodes 2 times and IC itself 3 times,
trying 2 different models. I am currently using CD40100BE IC, same
that is in instructables guide, previously I've tried
MC14584BDR2G.
I have also measured voltages throughout whole circuit.
All voltages are referenced to ground.
I think the problem is that 7V here is detected as HIGH by IC and
being inverted back to 0V, but then why people didn't have
problems like this before?
And how can I solve it once for all.
Voltage from Alice zeners is 12.33V (previously on 200V range it
measured 12.2V, thats the reason why it's different in graphic)
Both XLR pins measure 20.9V
^^^^ All voltages here were measured with DC
setting on multimeter
Thanks for any advice
Wiktor Molak
|
Hex inverter issue. Alice OPA
Hello, I am currently going through mental breakdown because of this circuit! I have no idea why it's not working, I'm beginner with electric circuits, simply following guides out there, schematics, so incase you want to help me out, please keep that in mind. Circuit is giving me only 32V on last diode, all my connections are good, I've replaced diodes 2 times and IC itself 3 times, trying 2 different models. I am currently using CD40100BE IC, same that is in instructables guide, previously I've tried MC14584BDR2G. I have also measured voltages throughout whole circuit.  All voltages are referenced to ground. I think the problem is that 7V here is detected as HIGH by IC and being inverted back to 0V, but then why people didn't have problems like this before? And how can I solve it once for all. Voltage from Alice zeners is 12.33V (previously on 200V range it measured 12.2V, thats the reason why it's different in graphic) Both XLR pins measure 20.9V
^^^^ All voltages here were measured with DC setting on multimeter
Thanks for any advice Wiktor Molak
|
Hi All,?
(Mainly FAO Jules, but I thought this discussion would be useful to a others)
What would be the best way of introducing a pattern switch to the rather than extracting two separate signals from the mic?
I totally understand Jules' reasons for pulling two signals from the mic where it's much easier to switch pattern on a desk than to fumble around with the mic. However I'm lacking a polarity inverter (?) in my mixing desk so want to be able to do it in-mic.
I've got this CK12 style edge-terminated capsule from AliExpress:?
I'm using the Dual OPA Alice circuit with DC-DC hex inverter multiplier to provide capsule bias. I'm using Jules' PCBs (, ) from PCB Way
I'd quite like to switch between cardioid, omni and figure-of-8, but without having to generate a negative bias voltage for the rear capsule. Given that there are two dual OPAs in the circuit outputting a fully balanced signal, surely there's a way to mix them in the mic by swapping the outputs of one of them when needed?
i.e. using a double-pole triple-throw switch on the rear capsule OPA balanced output
- Cardioid: rear capsule OPA outputs not connected
- Omni: rear capsule OPA outputs connected to front capsule OPA outputs in phase?
- Figure-of-8: rear capsule OPA outputs connected to front capsule OPA outputs out of phase (swapped over)
Would that work? Could I get away with a passive resistor-based mixer for the front + rear signals? Or am I going to be looking at adding another op-amp here (do we even have any more current headroom from phantom power)? Cheers, Mike
?
?
|
In this particular case, the foam does not seem to play any acoustic role: it's in the path of no soundwave. It appears to me to just beign a soft intermediary (damping?) layer between the backplate assembly and the retaining clip. I suppose I could replace it with any thick fabric or thin felt...
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Le 2022-04-08 10:17, Dibutil Ftalat a ¨¦crit?: The foam besides dimensions has the following characteristics:
- density
- size of cell
- % open cell
- Young's modulus of the foam
- Young's modulus of the material
- acoustical Q-factor
If you match all of the above you _may_ recover the original acoustic
properties of the mic. If not, then adding any foam is as good or
worse than leaving it without any foam at all.
Hint: open-cell foam is best cut with razor-sharp blade when the foam
is fully soaked with water or, better yet, fully submerged in it.
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I HAVE HAD GOOD RESLTS CUTING FOME WITH ELECTRIK CARVING KNIFE and stitching to gether the end¡¯s with fine sowing thread and then turning the fome tube incideout???? ??This teck-neek is good to make a wind sock to fit over the out cede of the mick ?and is cost effive and doesn¡¯t need to be soaked with water ???? PS foam cut this way makes the building of microphone transporting boxes easy? kind regards Stephen Muir-Field ? Sent from for Windows ?
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From: Dibutil FtalatSent: 08 April 2022 15:19 To: [email protected]Subject: Re: [MicBuilders] Foam rot in AT3528 ? The foam besides dimensions has the following characteristics:
- density
- size of cell
- % open cell
- Young¡¯s modulus of the foam
- Young¡¯s modulus of the material
- acoustical Q-factor
If you match all of the above you _may_ recover the original acoustic properties of the mic. If not, then adding any foam is as good or worse than leaving it without any foam at all.?
Hint: open-cell foam is best cut with razor-sharp blade ?when the foam is fully soaked with water or, better yet, fully submerged in it.?
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REVEIL 9 - dawn chorus radio broadcast over 30/4 to 1/5 2022
Dear MicBuilders
Each year on Dawn Chorus Day, we organise a 24+1 hour radio broadcast that circles the earth on live audio ?streams at daybreak.
Many of the microphones used by streamers as the sun reaches their location are based on recipes and advice from this list.
We would be delighted if you would like to add a live stream to this collective project!
For more information, please see the call for streams:
If you have questions, let us know.
Thanks and best wishes
Grant
Soundcamp
|
STEPHEN MUIR-FIELD
