I will try my best to explain, but Scott, Jules, and Homero can probably answer this better than I can. The "Alice" mic was, as I understand it a minimal parts take on the classic SCHOEPS design. Since it worked really, really well, the design has been used and improved upon.??Homero's "Pimped Alice" has biasing pots, LF EQ, and more improvements to the original circuit.?Jules created the "OPA-based Alice", which is essentially an OPAMP-based Alice circuit since the FETs used in the original circuit are getting harder and harder to get. In summary, I would say that an Alice Microphone, is any microphone that is based upon the original?"Alice" circuit, which is essentially a low part SCHOEPS design.?
-Germar
On Thu, Apr 14, 2022 at 2:02 PM Mic Scharf < micscharf@...> wrote: I think the name Alice (in microphones) was created by Scott Helmke. If I remember correctly, it was based on 16mm capsule and a FET circuit.
Now I see "Alice" all over in the mic DIY communities.? Homero Leal calls his "Pimped Alice". Jules Ryckebusch calls his "OPA based Alice".
What defines a microphone an Alice?
|
I think the name Alice (in microphones) was created by Scott Helmke. If I remember correctly, it was based on 16mm capsule and a FET circuit.
Now I see "Alice" all over in the mic DIY communities.? Homero Leal calls his "Pimped Alice". Jules Ryckebusch calls his "OPA based Alice".
What defines a microphone an Alice?
|
Re: Pat's Mic (Fetzer Valve Mic)
Why do you need RD1 and RD2, wouldn't be one RD enough? Same for RS.
Would we need a HexInverter or something else for the polarisation Voltage?
With the OPA and the Fet and T1 could there be a problem with the current from the Phantompower?
|
Re: Microphone w/ built in compression? “Lamplifier”
Such a strange combination of uC, ASP/DSP and outdated tech.
Seems ludicrous to me. I believe the absence of commercial success
attests it.
It will probably go in the gallery of irrealistic inventions with
the GPS wheelbarrow and the computer-controlled candle stick.
This guy probably spent a fortune in legal fees. Someone should
have told him his best protection was the unattractiveness of his
invention.
Le 14/04/2022 à 05:16, M H a écrit?:
toggle quoted message
Show quoted text
Here is the patent if anyone is interested.
|
Re: Microphone w/ built in compression? “Lamplifier”
Here is the patent if anyone is interested.
|
Re: Pat's Mic (Fetzer Valve Mic)
Homero,
That's a really cool project and a nice tribute to Pat.?
Would love to hear a comparison to a regular mic.
Thanks,
-Scott
On 4/12/22 20:22, Homero Leal wrote:
HI folks!
As some of you may know, one of the dreams of our friend Patrick
Davis (aka. P@T,
Enjoybiking) was the idea of designing a mic that could have the
"tube" sound, but that could also be very cheap to build.
We discussed the topic many times, and the idea of having a solid
state tube emulation was a really fascinating option that was
always on the table.
Some time ago I found a paper from Dimitri Danyuk called "Triode
Emulator", and in this paper he proposes very a simple way to
"emulate" triode behavior using a JFET with very specific values
for drain and source resistors.
Later, I found this page:
Which provides a way to calculate (look at the end of the page)
the required drain and source resistor values using some JFET
parameters like:
And also the input voltage of the circuit (VCC).
So, I decided to try a design using the Dimitri Danyuk approach,
with the values calculated from the Fetzer Valve page.
You could find the schematic here:
/g/MicBuilders/files/Homero%20Leal%27s%20Files/Pat%27s%20Mic/Pat%27s%20Mic.png
Circuit design uses a Charge Amplifier input stage, a JFET middle
stage (providing the "valve" tone"), and finally a impedance
balanced output stage with a Sallen Key HPF at about 19.XHz.
Also, a custom voltage regulator is used, using a BC549C NPN and a
zener, very similar to the one used on some very known chinese
mics. This VR provides about 9.4V for VCC.
I used two drain resistors and two source resistors, so it could
be easier to approach the right values calculated by the Fetzer
Valve page, by using the combination of two resistors.
As the JFET stage may have an amplification level on the signal, I
also used two capacitors for the charge amplifier, this way you
could reduce output level by placing an additional capacitor (some
math required).
I know the design may have some room for improvement, but I can
confirm I have working mic with this design, and it seems to my
untrained ear, that it has a very sleek and warm sound, very
similar to the sound of the valve mics.
For the build, I used a cheap Zramo donor mic from Amazon, which
that very nice 26mm electret capsule we have talked about before.
I decided to name this schematic? "Pat's Mic"...
in memory of our friend and former member of this group, P@T?(Patrick
Davis, R.I.P.)
This post is for your review and consideration, and please if you
have any ideas for improvement, don't hesitate to let me know.
Thank you, and kind regards!
HL
--
---- Scott Helmke ---- scott@... ---- (734) 604-9340 ----
"I have ceased distinguishing between the religious and the secular,
for everything is holy" - Joe Henry
|
Re: Budget self-made condenser capsule (PCB based backplate!)
I’m impressed! I look forward to your news of your progress!
Here's the results of a triangle shaped capsule, inspired by Ehrlund.?
I've shaved off a lot of the parasitic capacitance and the output is definitely higher. It's still sounding pretty narrowband mid-heavy. This one was done with about 150g of weight for membrane tension and the usual Scotch tape as a spacer.
I'm going to try increasing the backplate thickness with a second layer of PCB or maybe some acrylic to see if it gives better highs.
-- Phil Manning ~ classic recording studio
~piano tuning & serviceAjax studio: 905.231.3189
Pickering shop/office: 416.907.3562
cell: 905.626.3727
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Dude, that is amazing! Excellent?work.
Here's the results of a triangle shaped capsule, inspired by Ehrlund.?
I've shaved off a lot of the parasitic capacitance and the output is definitely higher. It's still sounding pretty narrowband mid-heavy. This one was done with about 150g of weight for membrane tension and the usual Scotch tape as a spacer.
I'm going to try increasing the backplate thickness with a second layer of PCB or maybe some acrylic to see if it gives better highs.
-- Best Regards,
Jules Ryckebusch
214 399 0931
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Here's the results of a triangle shaped capsule, inspired by Ehrlund.?
I've shaved off a lot of the parasitic capacitance and the output is definitely higher. It's still sounding pretty narrowband mid-heavy. This one was done with about 150g of weight for membrane tension and the usual Scotch tape as a spacer.
I'm going to try increasing the backplate thickness with a second layer of PCB or maybe some acrylic to see if it gives better highs.
|
following Homero's Fetzervalve thread, I'm wondering, is it reasonable to dream about emulating the coloration of a transformer on the output of a transformerless mic?
Please take this from a studio dreamer, I'm hardly a technician, not even close...
Phil Manning ~ classic recording studio
~piano tuning & serviceAjax studio: 905.231.3189
Pickering shop/office: 416.907.3562
cell: 905.626.3727
|
Re: Pat's Mic (Fetzer Valve Mic)
I love this “Fetzervalve” idea and would certainly build a couple - I regret that I’m not very technical and have no “feedback” to offer but I so appreciate this group (even though I mostly lurk in the shadows!)
I want to express support and encouragement to you, Homero, in pursuing this - if it means anything I’ll gladly be in line to obtain a couple PCBs early on
Cheers, Phil
Thank you Germar! The final version of the PCB will be available?as a PCBWay Shared Project. Just would like to have any feedback from the group before it goes final.
Regards!
HL
Hey?Homero, what a lovely way to remember P@T and a great idea too. I have only ever used the fetzervalve (FETs or Valve) as a guitar pedal and never would have dreamed of using it in a mic! Any change of you creating PCBs of this?
Kind regards, Germar Tischler
HI folks!
As some of you may know, one of the dreams of our friend Patrick Davis (aka. P@T, Enjoybiking) was the idea of designing a mic that could have the "tube" sound, but that could also be very cheap to build.
We discussed the topic many times, and the idea of having a solid state tube emulation was a really fascinating option that was always on the table.
Some time ago I found a paper from Dimitri Danyuk called "Triode Emulator", and in this paper he proposes very a simple way to "emulate" triode behavior using a JFET with very specific values for drain and source resistors.
Later, I found this page:
Which provides a way to calculate (look at the end of the page) the required drain and source resistor values using some JFET parameters like:
And also the input voltage of the circuit (VCC).
So, I decided to try a design using the Dimitri Danyuk approach, with the values calculated from the Fetzer Valve page.
You could find the schematic here:
/g/MicBuilders/files/Homero%20Leal%27s%20Files/Pat%27s%20Mic/Pat%27s%20Mic.png
Circuit design uses a Charge Amplifier input stage, a JFET middle stage (providing the "valve" tone"), and finally a impedance balanced output stage with a Sallen Key HPF at about 19.XHz.
Also, a custom voltage regulator is used, using a BC549C NPN and a zener, very similar to the one used on some very known chinese mics. This VR provides about 9.4V for VCC.
I used two drain resistors and two source resistors, so it could be easier to approach the right values calculated by the Fetzer Valve page, by using the combination of two resistors.
As the JFET stage may have an amplification level on the signal, I also used two capacitors for the charge amplifier, this way you could reduce output level by placing an additional capacitor (some math required).
I know the design may have some room for improvement, but I can confirm I have working mic with this design, and it seems to my untrained ear, that it has a very sleek and warm sound, very similar to the sound of the valve mics.
For the build, I used a cheap Zramo donor mic from Amazon, which that very nice 26mm electret capsule we have talked about before.
I decided to name this schematic? "Pat's Mic"... in memory of our friend and former member of this group, P@T?(Patrick Davis, R.I.P.)
This post is for your review and consideration, and please if you have any ideas for improvement, don't hesitate to let me know.
Thank you, and kind regards!
HL
-- Phil Manning ~ classic recording studio
~piano tuning & serviceAjax studio: 905.231.3189
Pickering shop/office: 416.907.3562
cell: 905.626.3727
|
Re: Microphone w/ built in compression? “Lamplifier”
I think that might depend on where this is introduced into the signal path...
In the case of the Hammond circuit I posted above, the incandescent bulbs were fitted as two legs of the 'bridge' fitted across the amplifier output.
So no following gain stages, and no noise from the additional 'variable' resistors that the bulbs essentially were.
I don't think this type of compressor has much application at the mic preamp part of the signal path.?
3 main reasons:
? They need considerable audio power to function
? They're slow, so don't catch transients well.
? The attack and release times are essentially fixed, and are determined by the bulb characteristics?
As Wim has posted above though, they do still have some useful applications...
toggle quoted message
Show quoted text
On Wed, Apr 13, 2022 at 03:16 PM, Dibutil Ftalat wrote:
Would this technique not introduce a LOT of noise?
On the marketing side of things though it is a treasure chest: one could tune and sell lamps for different pre-sets of compression ratio, attack and release. And then charge extra for the sets of balanced lamps for stereo recording!
|
Re: Microphone w/ built in compression? “Lamplifier”
Le 13/04/2022 à 16:16, Dibutil Ftalat a écrit?: Would this technique not introduce a LOT of noise? Why would it?
|
Re: Microphone w/ built in compression? “Lamplifier”
Would this technique not introduce a LOT of noise?
On the marketing side of things though it is a treasure chest: one could tune and sell lamps for different pre-sets of compression ratio, attack and release. And then charge extra for the sets of balanced lamps for stereo recording!
|
Re: Pat's Mic (Fetzer Valve Mic)
Thank you Germar! The final version of the PCB will be available?as a PCBWay Shared Project. Just would like to have any feedback from the group before it goes final.
Regards!
HL
Hey?Homero, what a lovely way to remember P@T and a great idea too. I have only ever used the fetzervalve (FETs or Valve) as a guitar pedal and never would have dreamed of using it in a mic! Any change of you creating PCBs of this?
Kind regards, Germar Tischler
HI folks!
As some of you may know, one of the dreams of our friend Patrick Davis (aka. P@T, Enjoybiking) was the idea of designing a mic that could have the "tube" sound, but that could also be very cheap to build.
We discussed the topic many times, and the idea of having a solid state tube emulation was a really fascinating option that was always on the table.
Some time ago I found a paper from Dimitri Danyuk called "Triode Emulator", and in this paper he proposes very a simple way to "emulate" triode behavior using a JFET with very specific values for drain and source resistors.
Later, I found this page:
Which provides a way to calculate (look at the end of the page) the required drain and source resistor values using some JFET parameters like:
And also the input voltage of the circuit (VCC).
So, I decided to try a design using the Dimitri Danyuk approach, with the values calculated from the Fetzer Valve page.
You could find the schematic here:
/g/MicBuilders/files/Homero%20Leal%27s%20Files/Pat%27s%20Mic/Pat%27s%20Mic.png
Circuit design uses a Charge Amplifier input stage, a JFET middle stage (providing the "valve" tone"), and finally a impedance balanced output stage with a Sallen Key HPF at about 19.XHz.
Also, a custom voltage regulator is used, using a BC549C NPN and a zener, very similar to the one used on some very known chinese mics. This VR provides about 9.4V for VCC.
I used two drain resistors and two source resistors, so it could be easier to approach the right values calculated by the Fetzer Valve page, by using the combination of two resistors.
As the JFET stage may have an amplification level on the signal, I also used two capacitors for the charge amplifier, this way you could reduce output level by placing an additional capacitor (some math required).
I know the design may have some room for improvement, but I can confirm I have working mic with this design, and it seems to my untrained ear, that it has a very sleek and warm sound, very similar to the sound of the valve mics.
For the build, I used a cheap Zramo donor mic from Amazon, which that very nice 26mm electret capsule we have talked about before.
I decided to name this schematic? "Pat's Mic"... in memory of our friend and former member of this group, P@T?(Patrick Davis, R.I.P.)
This post is for your review and consideration, and please if you have any ideas for improvement, don't hesitate to let me know.
Thank you, and kind regards!
HL
|
Re: Microphone w/ built in compression? “Lamplifier”
FWIW:
I still use that technique to protect tweeters in DJ speakers... Op wo 13 apr. 2022 om 11:34 schreef Arjay 1949 < info@...>:
This technique reminded me of the same thing that was employed in Hammond organs, back in the day (1960s/70s).
They used light bulbs to 'limit' the drive to the inductive drivers on the spring reverb units.?
They were connected to the output of a power amp, and included the bulbs in the signal path itself.
As Jerry has already commented, using an audio signal to light an incandescent bulb requires a fair amount of power !? ??
The assembly in the sketch below was connected to the output of the reverb audio amp, so the 'sig. input' would normally have been a loudspeaker....
It used to alarm some customers that they could see an intermittent 'glow' under an amp chassis, when the service tech had the back off the instrument! :)
On Tue, Apr 12, 2022 at 11:12 PM, M H wrote:
Was looking around at passive limiters and such, and came across an interesting implementation in “Lamplifier Microphones”.? From what I can gather, the microphone has an internal preamp that lights a small incandescent bulb. Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression.
Just seemed clever in its simplicity.? Don’t know how it sounds though..? The website Lamplifier.com seems to be defunct and their contract info email box is full.? That might give me my verdict right there. ?
?Thought it might be fun to try with a tiny “grain-of wheat “ bulb..
|
Re: Microphone w/ built in compression? “Lamplifier”
This technique reminded me of the same thing that was employed in Hammond organs, back in the day (1960s/70s). They used light bulbs to 'limit' the drive to the inductive drivers on the spring reverb units.? They were connected to the output of a power amp, and included the bulbs in the signal path itself. As Jerry has already commented, using an audio signal to light an incandescent bulb requires a fair amount of power !? ?? The assembly in the sketch below was connected to the output of the reverb audio amp, so the 'sig. input' would normally have been a loudspeaker.... It used to alarm some customers that they could see an intermittent 'glow' under an amp chassis, when the service tech had the back off the instrument! :) 
On Tue, Apr 12, 2022 at 11:12 PM, M H wrote:
Was looking around at passive limiters and such, and came across an interesting implementation in “Lamplifier Microphones”. ?From what I can gather, the microphone has an internal preamp that lights a small incandescent bulb. Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression.
Just seemed clever in its simplicity. ?Don’t know how it sounds though.. ?The website Lamplifier.com seems to be defunct and their contract info email box is full. ?That might give me my verdict right there. ?
?Thought it might be fun to try with a tiny “grain-of wheat “ bulb..
|
Re: Pat's Mic (Fetzer Valve Mic)
Hey?Homero, what a lovely way to remember P@T and a great idea too. I have only ever used the fetzervalve (FETs or Valve) as a guitar pedal and never would have dreamed of using it in a mic! Any change of you creating PCBs of this?
Kind regards, Germar Tischler
HI folks!
As some of you may know, one of the dreams of our friend Patrick Davis (aka. P@T, Enjoybiking) was the idea of designing a mic that could have the "tube" sound, but that could also be very cheap to build.
We discussed the topic many times, and the idea of having a solid state tube emulation was a really fascinating option that was always on the table.
Some time ago I found a paper from Dimitri Danyuk called "Triode Emulator", and in this paper he proposes very a simple way to "emulate" triode behavior using a JFET with very specific values for drain and source resistors.
Later, I found this page:
Which provides a way to calculate (look at the end of the page) the required drain and source resistor values using some JFET parameters like:
And also the input voltage of the circuit (VCC).
So, I decided to try a design using the Dimitri Danyuk approach, with the values calculated from the Fetzer Valve page.
You could find the schematic here:
/g/MicBuilders/files/Homero%20Leal%27s%20Files/Pat%27s%20Mic/Pat%27s%20Mic.png
Circuit design uses a Charge Amplifier input stage, a JFET middle stage (providing the "valve" tone"), and finally a impedance balanced output stage with a Sallen Key HPF at about 19.XHz.
Also, a custom voltage regulator is used, using a BC549C NPN and a zener, very similar to the one used on some very known chinese mics. This VR provides about 9.4V for VCC.
I used two drain resistors and two source resistors, so it could be easier to approach the right values calculated by the Fetzer Valve page, by using the combination of two resistors.
As the JFET stage may have an amplification level on the signal, I also used two capacitors for the charge amplifier, this way you could reduce output level by placing an additional capacitor (some math required).
I know the design may have some room for improvement, but I can confirm I have working mic with this design, and it seems to my untrained ear, that it has a very sleek and warm sound, very similar to the sound of the valve mics.
For the build, I used a cheap Zramo donor mic from Amazon, which that very nice 26mm electret capsule we have talked about before.
I decided to name this schematic? "Pat's Mic"... in memory of our friend and former member of this group, P@T?(Patrick Davis, R.I.P.)
This post is for your review and consideration, and please if you have any ideas for improvement, don't hesitate to let me know.
Thank you, and kind regards!
HL
|
Re: Microphone w/ built in compression? “Lamplifier”
No. They use small incandescent light bulbs.
This type of passive limiter requires substantial level to
operate. The signal from a microphone is too weak, so it must be
amplified. That means there should be a battery in the mic, which
is quite inconvenient.
Le 13/04/2022 à 02:38, Tom Becker a
écrit?:
toggle quoted message
Show quoted text
... Said bulb, as it starts to glow, becomes higher
resistance to signal, functioning as a form of audio
compression...
Probably a Vactrol optically-controlled variable resistance.?
Like:
|
Pat's Mic (Fetzer Valve Mic)
HI folks! As some of you may know, one of the dreams of our friend Patrick Davis (aka. P@T, Enjoybiking) was the idea of designing a mic that could have the "tube" sound, but that could also be very cheap to build. We discussed the topic many times, and the idea of having a solid state tube emulation was a really fascinating option that was always on the table. Some time ago I found a paper from Dimitri Danyuk called "Triode Emulator", and in this paper he proposes very a simple way to "emulate" triode behavior using a JFET with very specific values for drain and source resistors. Later, I found this page: Which provides a way to calculate (look at the end of the page) the required drain and source resistor values using some JFET parameters like:
And also the input voltage of the circuit (VCC). So, I decided to try a design using the Dimitri Danyuk approach, with the values calculated from the Fetzer Valve page. You could find the schematic here: /g/MicBuilders/files/Homero%20Leal%27s%20Files/Pat%27s%20Mic/Pat%27s%20Mic.pngCircuit design uses a Charge Amplifier input stage, a JFET middle stage (providing the "valve" tone"), and finally a impedance balanced output stage with a Sallen Key HPF at about 19.XHz. Also, a custom voltage regulator is used, using a BC549C NPN and a zener, very similar to the one used on some very known chinese mics. This VR provides about 9.4V for VCC. I used two drain resistors and two source resistors, so it could be easier to approach the right values calculated by the Fetzer Valve page, by using the combination of two resistors. As the JFET stage may have an amplification level on the signal, I also used two capacitors for the charge amplifier, this way you could reduce output level by placing an additional capacitor (some math required). I know the design may have some room for improvement, but I can confirm I have working mic with this design, and it seems to my untrained ear, that it has a very sleek and warm sound, very similar to the sound of the valve mics. For the build, I used a cheap Zramo donor mic from Amazon, which that very nice 26mm electret capsule we have talked about before. I decided to name this schematic? " Pat's Mic"... in memory of our friend and former member of this group, P@T?(Patrick Davis, R.I.P.) This post is for your review and consideration, and please if you have any ideas for improvement, don't hesitate to let me know. Thank you, and kind regards! HL
|
Mic Scharf
Phil Manning
Dibutil Ftalat