Re: Budget self-made condenser capsule (PCB based backplate!)
Though not Mylar (and not as tough), you maybe could try ultra thin aluminum like the ribbon mic folk use:?
could spray coat one side with a nonconductive lacquer if need be.
Or, if you want to go cheaper than that, you could get some “imitation silver leaf”. ?But that is extremely fragile and frustrating to work with, so..?
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Microphone w/ built in compression? “Lamplifier”
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..
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Re: Budget self-made condenser capsule (PCB based backplate!)
I have reskinned damaged capsules with aluminized mylar unrolled from film capacitors. The lower the voltage rating, the thinner the film is.?The capsules have sounded fine, though likely not good as new.
I tried making capsules with perforated aluminum sheet as backplate, Scotch tape, and mylar film. They did pick up sound: poorly, not as well as a cheap electret. Like you, I wonder how shape and backplate geometry affects tone. Your method is better because you can isolate the active area of the backplate by etching, and reduce the parasitic fixed capacitance. Good work!
The resistance of the diaphragm doesn't matter much, especially if signal is taken off the backplate. All it has to do is hold a constant charge.
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Re: Source of dynamic capsules?
Well that's precisely what bothers me: there seems to be no options...
I'm not a big fan of the 58 sound, and would like to get something less hyped, more extended...
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Re: Source of dynamic capsules?
I've tried different Chinese companies?for 57 and 58 diaphragms advertised on EBay. At about ?4 to ?5 delivered
I'm in the UK and cant tell the difference live on P.A? (I HAVE OTHER GENUINE SM57 AND SM58)?
Quality seems excellent and totally interchangeable.
Dow Fereday
LTSSTUDIO.COM
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Re: Source of dynamic capsules?
I went to AliExpress to see: there is a great many choice of capsules, unfortunately with about no information at all. Nosem and Takstar brands seem to be the most widespread. It's like shooting in the dark...
So I did that, and ordered an assortment of disparate capsules:
Nosem N-316 (very cheap at $2.38)
Something slated as replacement for Sennheiser EW100, unknown brand ($12.79)
Takstar TS-5 ($14.11). However, i'm told by the Takstar store they are unavailable. I don't know if that's temporary or permanent, I sure hope it's not permanent as this capsule seems to be the best around, from comments here .
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Re: Budget self-made condenser capsule (PCB based backplate!)
Hallo,? sorry for my mistake.? But, please let me say something to your comment. Just to clarify, you‘re saying that Most backplates are made out of solid brass. You are completly right and this was exactly what I just wanted to say - they should be stiff. There is a different type of capsules which have a second membrahne of course. No matter of this membrahne is passive or used for pattern ?switching , this one works ?in a 180 degree? Greetings and thanks Ralf
Hi Ralf,
It's not me that's building a capsule, it's michaeljtbrooks.
However, I can make some comments:
"2- the backplate cannot be stiff enough. That is one reason
for partial cancelation of higher frequencies. This is because
if it is not it will probably cancel out frequencies by slightly
moving by soundpressure in the opposit direction of the
membrahne."
I'm not convinced. The backplate would need to be very flexible to
react in such a way. Most of the backplates are made of a piece of
metal (often brass) that is millions of times heavier and more
rigid than the diaphragm.
"3- the backplate had to be fairly thick so that you can make
some sackholes in it for damping ?reasons "
Indeed, blind holes (as well as through-holes) are necessary for
providing damping of the diaphragm
Le 12/04/2022 à 12:38, Ralf Falk a
écrit?:
Hey, Jerry Lee,
my namens Ralf and this is the first reply ?in
this forum. I‘ m writing from Germany so please ? ? excuse my
bad language.
About 10 years ago I made a very similar
experiment wich I stopped as I got me a lath to work with. I
found out the same things that you posted here and came to the
following conclusions:
1- It is important to get the membrahn streched
the same degree to all sides?
2- the backplate cannot be stiff enough. That is
one reason for partial cancelation of higher frequencies. This
is because if it is not it will probably cancel out frequencies
by slightly moving by soundpressure in the opposit direction of
the membrahne.
3- the backplate had to be fairly thick so that
you can make some sackholes in it for damping ?reasons?
4- to get rid of most of the parasitic
capacitance, you simply should take of the copper of your
backplate piece in the airia where the frame that holds your
membrahn will be positioned?
I hope that this will bring you in a good
direction.
Good luck?
I'm pretty suspicious of the
membrane resistance which is a few ohms per cm2 as the
culprit. So any suggestions for more conductive
aluminiumised Mylar would be greatly appreciated!
Whatever few ohms there don't matter compared to the
Gigaohm input resistance of the Alice circuit.
Look elsewhere. Surely 20 micron thickness does not help
with sensitivity, but all the parasitic capacitances are
probably the main culprit.
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Re: Budget self-made condenser capsule (PCB based backplate!)
Hi Ralf,
It's not me that's building a capsule, it's michaeljtbrooks.
However, I can make some comments:
"2- the backplate cannot be stiff enough. That is one reason
for partial cancelation of higher frequencies. This is because
if it is not it will probably cancel out frequencies by slightly
moving by soundpressure in the opposit direction of the
membrahne."
I'm not convinced. The backplate would need to be very flexible to
react in such a way. Most of the backplates are made of a piece of
metal (often brass) that is millions of times heavier and more
rigid than the diaphragm.
"3- the backplate had to be fairly thick so that you can make
some sackholes in it for damping ?reasons "
Indeed, blind holes (as well as through-holes) are necessary for
providing damping of the diaphragm
Le 12/04/2022 à 12:38, Ralf Falk a
écrit?:
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Hey, Jerry Lee,
my namens Ralf and this is the first reply ?in
this forum. I‘ m writing from Germany so please ? ? excuse my
bad language.
About 10 years ago I made a very similar
experiment wich I stopped as I got me a lath to work with. I
found out the same things that you posted here and came to the
following conclusions:
1- It is important to get the membrahn streched
the same degree to all sides?
2- the backplate cannot be stiff enough. That is
one reason for partial cancelation of higher frequencies. This
is because if it is not it will probably cancel out frequencies
by slightly moving by soundpressure in the opposit direction of
the membrahne.
3- the backplate had to be fairly thick so that
you can make some sackholes in it for damping ?reasons?
4- to get rid of most of the parasitic
capacitance, you simply should take of the copper of your
backplate piece in the airia where the frame that holds your
membrahn will be positioned?
I hope that this will bring you in a good
direction.
Good luck?
I'm pretty suspicious of the
membrane resistance which is a few ohms per cm2 as the
culprit. So any suggestions for more conductive
aluminiumised Mylar would be greatly appreciated!
Whatever few ohms there don't matter compared to the
Gigaohm input resistance of the Alice circuit.
Look elsewhere. Surely 20 micron thickness does not help
with sensitivity, but all the parasitic capacitances are
probably the main culprit.
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Re: Budget self-made condenser capsule (PCB based backplate!)
Hey, Jerry Lee, my namens Ralf and this is the first reply ?in this forum. I‘ m writing from Germany so please ? ? excuse my bad language. About 10 years ago I made a very similar experiment wich I stopped as I got me a lath to work with. I found out the same things that you posted here and came to the following conclusions: 1- It is important to get the membrahn streched the same degree to all sides? 2- the backplate cannot be stiff enough. That is one reason for partial cancelation of higher frequencies. This is because if it is not it will probably cancel out frequencies by slightly moving by soundpressure in the opposit direction of the membrahne. 3- the backplate had to be fairly thick so that you can make some sackholes in it for damping ?reasons? 4- to get rid of most of the parasitic capacitance, you simply should take of the copper of your backplate piece in the airia where the frame that holds your membrahn will be positioned?
I hope that this will bring you in a good direction.
Good luck?
I'm pretty suspicious of the membrane resistance which is a few
ohms per cm2 as the culprit. So any suggestions for more
conductive aluminiumised Mylar would be greatly appreciated!
Whatever few ohms there don't matter compared to the Gigaohm input
resistance of the Alice circuit.
Look elsewhere. Surely 20 micron thickness does not help with
sensitivity, but all the parasitic capacitances are probably the
main culprit.
|
Re: Budget self-made condenser capsule (PCB based backplate!)
I'm pretty suspicious of the membrane resistance which is a few
ohms per cm2 as the culprit. So any suggestions for more
conductive aluminiumised Mylar would be greatly appreciated!
Whatever few ohms there don't matter compared to the Gigaohm input
resistance of the Alice circuit.
Look elsewhere. Surely 20 micron thickness does not help with
sensitivity, but all the parasitic capacitances are probably the
main culprit.
|
Re: Budget self-made condenser capsule (PCB based backplate!)
What impedance converter (head amp) are you using?
What polarization voltage (bias) are you using?
What preamp?
It is more of a relative observation. A Chinese K87-style capsule with exactly the same circuit gives a hotter output, requiring 11 o-clock on the gain.
Headphone amplifier: Behringer DX2000 mixer
Polarization voltage: 72V from a Jules' DC-DC Hex multiplier
Preamp: OPA Alice (OPA1642) phantom powered.
I'm pretty suspicious of the membrane resistance which is a few ohms per cm2 as the culprit. So any suggestions for more conductive aluminiumised Mylar would be greatly appreciated!
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Re: Budget self-made condenser capsule (PCB based backplate!)
Interesting project.
I made a basic omni circular capsule many years ago (I had access to a friends lathe and pretty well equipped workshop at the time).? Diaphragm material was an issue (especially as I had very limited income), but I did get it working.? It's certainly possible.? Good luck.
Every Blessing
Tony
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On 12/04/2022 08:01, Jerry Lee Marcel wrote:
Le 11/04/2022 à 23:43, michaeljtbrooks@... a écrit?:
The output levels are pretty low, needing about 3 o-clock on the gain to get a reasonable signal.
What impedance converter (head amp) are you using?
What polarization voltage (bias) are you using?
What preamp?
--
This email has been checked for viruses by AVG.
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Re: Budget self-made condenser capsule (PCB based backplate!)
Le 11/04/2022 à 23:43, michaeljtbrooks@... a écrit?:
The output levels are pretty low, needing about 3 o-clock on the gain to get a reasonable signal.
What impedance converter (head amp) are you using? What polarization voltage (bias) are you using? What preamp?
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Re: Budget self-made condenser capsule (PCB based backplate!)
Really amazing! Brilliant! All encouragement
Best wishes
David P
I've been doing the thing that you're not supposed to do: building my own condenser capsules. I thought I'd share my technique.
I wanted to experiment with the shape of the capsule, membrane tension, and pattern of backplate holes to get a feel for the difference it makes. However my metalwork skills suck, and I only have soldering equipment and a desktop CNC milling machine to hand. I also wanted each capsule to be cheap to make because the intention is to make a variety of shapes / hole patterns to see what effect this has.
So I've been building them from unetched sheets of copper-clad PCB (exploded view):
Cheap space blankets seem to make viable membranes for experimenting, being conductive on one side and about 20?m thick. Scotch tape is a great insulation spacer being only 60?m thick. The generic PCB you can get seems to have a very uniform surface though I've not measured it.
I'm using my desktop CNC milling machine to drill the backplate and faceplate holes and to cut the faceplate aperture. I'm then using a Dremel to polish the backplate and take off any little shards on the cut edges.
To tension the membrane, I've simply been stretching it over a 80mm large metal ring conducting side down, using PVC tape to tack it down so it's visibly flat. Then once I've applied the Scotch tape perimeter to the backplate with a very thin layer of glue, I place the backplate face-down on the membrane and position a weight on top. After about 15 minutes I can cut the membrane free from the ring. Then I position the faceplate, prick through the mounting holes with a needle and push through the nylon bolts and fasten with nylon nuts. I then solder the backplate and faceplate leads. The final step is to fold the Mylar edges over the faceplate and tape them down to make electrical contact.? I found that putting the faceplate copper-side down always caused shorts to the backplate, likely around the mouting holes and it would happen no matter how careful I was.
The capacitance measures 250-800pF depending on capsule size. Some of that is from the clamped section of the membrane.
So far the capsules are quite resonant in the mid frequencies, but disappointingly lacking in the highs, rolling off above 10kHz. The low end response seems to depend strongly on tension, the slacker leading to more prominent lows. The output levels are pretty low, needing about 3 o-clock on the gain to get a reasonable signal. I'm not sure if this is to do with the mass of the membrane or due to the membrane resistance (~3 ohms per 10mm).?
Does anyone know of source of low resistance 6?m aluminiumised Mylar? I'm not keen to go ripping apart electrolytic caps if I can get my hands on factory samples!
-- - - - - - - - - - - - - - - - - - - - - - - - -
David Pinnegar, B.Sc., A.R.C.S.
- - - - - - - - - - - - - - - - - - - - - - - -
+44 1342 850594
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Re: Budget self-made condenser capsule (PCB based backplate!)
Awesome! And yes…. You are “supposed to do that” lol! Best Regards,
Jules Ryckebusch?
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On Apr 11, 2022, at 16:43, michaeljtbrooks@... wrote:
? I've been doing the thing that you're not supposed to do: building my own condenser capsules. I thought I'd share my technique.
I wanted to experiment with the shape of the capsule, membrane tension, and pattern of backplate holes to get a feel for the difference it makes. However my metalwork skills suck, and I only have soldering equipment and a desktop CNC milling machine to hand. I also wanted each capsule to be cheap to make because the intention is to make a variety of shapes / hole patterns to see what effect this has.
So I've been building them from unetched sheets of copper-clad PCB (exploded view):
Cheap space blankets seem to make viable membranes for experimenting, being conductive on one side and about 20?m thick. Scotch tape is a great insulation spacer being only 60?m thick. The generic PCB you can get seems to have a very uniform surface though I've not measured it.
I'm using my desktop CNC milling machine to drill the backplate and faceplate holes and to cut the faceplate aperture. I'm then using a Dremel to polish the backplate and take off any little shards on the cut edges.
To tension the membrane, I've simply been stretching it over a 80mm large metal ring conducting side down, using PVC tape to tack it down so it's visibly flat. Then once I've applied the Scotch tape perimeter to the backplate with a very thin layer of glue, I place the backplate face-down on the membrane and position a weight on top. After about 15 minutes I can cut the membrane free from the ring. Then I position the faceplate, prick through the mounting holes with a needle and push through the nylon bolts and fasten with nylon nuts. I then solder the backplate and faceplate leads. The final step is to fold the Mylar edges over the faceplate and tape them down to make electrical contact.? I found that putting the faceplate copper-side down always caused shorts to the backplate, likely around the mouting holes and it would happen no matter how careful I was.
The capacitance measures 250-800pF depending on capsule size. Some of that is from the clamped section of the membrane.
So far the capsules are quite resonant in the mid frequencies, but disappointingly lacking in the highs, rolling off above 10kHz. The low end response seems to depend strongly on tension, the slacker leading to more prominent lows. The output levels are pretty low, needing about 3 o-clock on the gain to get a reasonable signal. I'm not sure if this is to do with the mass of the membrane or due to the membrane resistance (~3 ohms per 10mm).?
Does anyone know of source of low resistance 6?m aluminiumised Mylar? I'm not keen to go ripping apart electrolytic caps if I can get my hands on factory samples!
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Budget self-made condenser capsule (PCB based backplate!)
I've been doing the thing that you're not supposed to do: building my own condenser capsules. I thought I'd share my technique.
I wanted to experiment with the shape of the capsule, membrane tension, and pattern of backplate holes to get a feel for the difference it makes. However my metalwork skills suck, and I only have soldering equipment and a desktop CNC milling machine to hand. I also wanted each capsule to be cheap to make because the intention is to make a variety of shapes / hole patterns to see what effect this has.
So I've been building them from unetched sheets of copper-clad PCB (exploded view):
Cheap space blankets seem to make viable membranes for experimenting, being conductive on one side and about 20?m thick. Scotch tape is a great insulation spacer being only 60?m thick. The generic PCB you can get seems to have a very uniform surface though I've not measured it.
I'm using my desktop CNC milling machine to drill the backplate and faceplate holes and to cut the faceplate aperture. I'm then using a Dremel to polish the backplate and take off any little shards on the cut edges.
To tension the membrane, I've simply been stretching it over a 80mm large metal ring conducting side down, using PVC tape to tack it down so it's visibly flat. Then once I've applied the Scotch tape perimeter to the backplate with a very thin layer of glue, I place the backplate face-down on the membrane and position a weight on top. After about 15 minutes I can cut the membrane free from the ring. Then I position the faceplate, prick through the mounting holes with a needle and push through the nylon bolts and fasten with nylon nuts. I then solder the backplate and faceplate leads. The final step is to fold the Mylar edges over the faceplate and tape them down to make electrical contact.? I found that putting the faceplate copper-side down always caused shorts to the backplate, likely around the mouting holes and it would happen no matter how careful I was.
The capacitance measures 250-800pF depending on capsule size. Some of that is from the clamped section of the membrane.
So far the capsules are quite resonant in the mid frequencies, but disappointingly lacking in the highs, rolling off above 10kHz. The low end response seems to depend strongly on tension, the slacker leading to more prominent lows. The output levels are pretty low, needing about 3 o-clock on the gain to get a reasonable signal. I'm not sure if this is to do with the mass of the membrane or due to the membrane resistance (~3 ohms per 10mm).?
Does anyone know of source of low resistance 6?m aluminiumised Mylar? I'm not keen to go ripping apart electrolytic caps if I can get my hands on factory samples!
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On Mon, Apr 11, 2022 at 08:22 PM, Mic Scharf wrote:
But this is not balanced or am I missing something?
Can we go further with this one?
This is only a quick 'concept' schematic.... As we have discussed in this thread already, the decision to use a single sided audio output does not affect the option of creating a balanced output.? The 'cold' side ( normally pin 3 , but in this case pin 2 because the summing amp inverts the signal) is taken to ground - via a matching output resistor and electrolytic capacitor - to create an impedance balanced output, which should help maintain a reasonable CMRR. As to taking it further - that would be down to whether anyone thinks it might be a good ide? ..... As I say, it's only a 'concept' sketch for discussion at present. One thing that springs to mind. Double sided capsules - particularly 'budget' Chinese ones are notorious for having slightly different output levels from each side. In this configuration it should be possible to correct that by adjusting the value of R3? - and possibly R6 as well? - to adjust the gain to match the output signal from the two sides of the capsule. Could help to improve the figure of 8 pattern, for example? As I say, just a suggestion for discussion at the moment...
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On Mon, Apr 11, 2022 at 03:46 PM, Arjay 1949 wrote:
I think you could try something like this..... You could use a dual OPA1642 and a single OPA1641.
By not regulating the op-amp supply, - and carefully selecting the feed resistors for the regulated voltage multiplier supply -? it should be possible to keep the total current drain to around 6 or 7mA, which is not so close to the phantom power current limit.?
I'm guessing this is the type of thing Jerry had in mind in post #3 of this thread?...
But this is not balanced or am I missing something?
Can we go further with this one?
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On Mon, Apr 11, 2022 at 01:40 PM, Mic Scharf wrote:
On Sat, Apr 9, 2022 at 07:31 PM, Arjay 1949 wrote:
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?.....
How would it be with 3 opamps? regarding not concentrating on the existing PCB
I think you could try something like this..... You could use a dual OPA1642 and a single OPA1641. By not regulating the op-amp supply, - and carefully selecting the feed resistors for the regulated voltage multiplier supply -? it should be possible to keep the total current drain to around 6 or 7mA, which is not so close to the phantom power current limit.? I'm guessing this is the type of thing Jerry had in mind in post #3 of this thread?... 
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On Sat, Apr 9, 2022 at 07:31 PM, Arjay 1949 wrote:
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?.....
How would it be with 3 opamps? regarding not concentrating on the existing PCB
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Mic Scharf