Re: Bipolar condenser for P48 basic with EM272?
Unless there is a need for a high pass filter, using a larger coupling cap won't hurt. Something that's often forgotten is the series reactance of a cap is a noise source, just like a series resistance. So if your coupling cap is 3dB down at 50Hz working into , say, 1K ohm, it has a noise contribution at 50HZ same as a 1K resistor. Even at 500Hz, it contributes as much noise as a 100 ohm resistor. In a mic, there is a tradeoff between noise and the need to high pass filter thumps and plosives.
The noise audibility is reduced by the Fletcher-Munson effect, but it's still there on spectral plots of many mics. I use larger caps than most engineers, because I think I can hear that LF noise.
|
Re: Bipolar condenser for P48 basic with EM272?
Understood. That last explanation about Bipolar was really refreshing from the old days, thanks!
Why people don't use? 10uf? 63V, or even 10uf 100V?
Is it only for the space it takes physically inside the XLR connector or there is something related that can affect the frequency response??
Cheers
|
Re: Bipolar condenser for P48 basic with EM272?
An aluminum electrolytic capacitor consists of two Al foil electrodes separated by a conductive electrolyte. Al forms an oxide coating on the surface on contact with air or water, and the oxide coating is the dielectric of the capacitor. So an Al electrolytic consists of two caps in series, one at the anode and one at the cathode. The anode is formed with the thicker oxide, is high voltage and lesser capacitance. The cathode is low voltage, a volt or two, and very high capacitance. The over all result is two caps in series, of which the anode primarily determines the voltage and capacity. It turns out the cathode contributes most of the tiny distortion to any signal passing through.
This is where it gets interesting. Bipolar electrolytics are NOT made as two polar caps in series. Bipolar caps have two anodes and no cathodes. Bipolar caps exhibit much less distortion than polar caps in audio coupling circuits. So to answer the OP question, bipolar caps are fine. They are actually preferred if they can be had in the desired voltage and capacity. They exhibit more than an order of magnitude less distortion. They are physically larger, because the two anodes in series have to be larger to reach the same capacity, but otherwise they are better, even in circuits where the polarity applied never changes.
Let me add that capacitor distortion is likely to be the least contributor to the sound of a mic, but still . . .
|
Re: Bipolar condenser for P48 basic with EM272?
We are probably worrying about nothing TBH. Jules @ Sound Sleuth designs excellent circuits, if he says it's good, it'll likely be good.
I can only see a problem if you're intending on capturing low frequencies (e.g. 30Hz) and feeding it into a mixer with low input impedance on its mic channel (e.g. <1000 ohms). If your mixer / sound card mic input is decent it'll have >1500 Ohm on its input and so you won't see a problem.
|
Re: Bipolar condenser for P48 basic with EM272?
The other issue is size of the capacitor. ?I¡¯m the 3.3uF 63V guy. ?They work great and physically allow you to build the SimpleP48 into the XLR connector. ?I use this with my ZoomF6. ? Best Regards,
Jules Ryckebusch?
toggle quoted message
Show quoted text
On Apr 21, 2022, at 07:51, a45porhora@... wrote:
?Thanks for the explanation Michael, the point about tolerance is really good. My plan is to connect that Mic's via XLR to a new Zoom F3, but better for a capacitor rated for at least 50V like this one: https://www.mouser.es/ProductDetail/Nichicon/UKW1H4R7MDD1TA?qs=WJSLByB5Mu28FaeGBvn6BQ%3D%3D About low frecuencies: Reading this: ?he says?
?The capacitor can be 1uF to 4.7uF without noticeable change in sound. I am using 3.3uF
What do you think about this? Cheers
|
Re: Bipolar condenser for P48 basic with EM272?
Thanks for the explanation Michael, the point about tolerance is really good. My plan is to connect that Mic's via XLR to a new Zoom F3, but better for a capacitor rated for at least 50V like this one: https://www.mouser.es/ProductDetail/Nichicon/UKW1H4R7MDD1TA?qs=WJSLByB5Mu28FaeGBvn6BQ%3D%3D About low frecuencies: Reading this: ?he says?
?The capacitor can be 1uF to 4.7uF without noticeable change in sound. I am using 3.3uF
What do you think about this? Cheers
|
Re: Bipolar condenser for P48 basic with EM272?
I've used both polar and bipolar in the signal lines in microphones. It doesn't make much difference so long as the capacitor value is sufficiently high to pass the low frequencies.
A bipolar electrolytic capacitor is simply the same as two polar electrolytic capacitors back-to-back (with their negative leads tied together or positive leads tied together). If you do put two in series like this, remember that their total capacitance will be half of each capacitor's value.
The Nichicon bipolar caps are excellent. Just make sure they are rated for at least 50V DC if using on Phantom Power (your one here is 35V). I tend to overspec the capacitor capacity so I don't lose low frequencies should whatever I'm sending the mic signal to have feeble input impedance, so I'd typically go for 10?F or above. Capacitor tolerances are often +/- 20% so at 4.7?F you could be as low as 3.7?F in reality, which could start blocking low frequencies if you connect it to a shoddy mixer with a low input impedance.
You would only actually need a bipolar if you're thinking of having switchable power (internal battery vs phantom). Otherwise a polar electrolytic with positive to the XLR side is fine.
|
Bipolar condenser for P48 basic with EM272?
Hi all!
After a lot of reading, I see for short cables (less than 2 meters) the Simple P48 circuit is enough for a good quality build.
My question here is: I see a lot of people talk about taking care of polarity on the Electrolytic Aluminum Capacitor, and I was thinking about using a Bipolar like this:
or this one:
Does it make any difference? As far I know using a Bipolar Capacitor you don't have to pay attention to this and I don't know if using a Bipolar Capacitor will produce the same good results as a normal Capacitor
|
Re: Budget self-made condenser capsule (PCB based backplate!)
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!
Fig-8.doc in my FILES directory describes a Fig-8 capsule I designed some 40+ yrs ago for Calrec.? It has sources for 5 & 10 um Aluminised Mylar and other useful info.
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Excellent result -- well done! :)
I must confess I didn't think I was going to hear something quite that impressive, when I first downloaded your mp3....
If one could create a version with a capacitance of around 70 - 80pF, and with a low tension membrane, it would be fascinating to know how that would perform in an RF bias mic configuration.
(Some notes here for circuit ideas: )
The commercial RF mics from Sennheiser use a lower tensioned membrane ... feasible simply because there is only around 3 or 4 volts of? RF across the capsule, as opposed to the 60 or 70v DC in a conventional condenser configuration. Helps quite a lot with sensitivity, apparently?..
Low impedance as well --- makes worrying about screening a bit less important! :)
Just a thought...
toggle quoted message
Show quoted text
On Mon, Apr 18, 2022 at 07:30 PM, <michaeljtbrooks@...> wrote:
Full Instructable now available here:
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Excellent!!!! More microphone Instructables! Best Regards,
Jules Ryckebusch?
toggle quoted message
Show quoted text
On Apr 18, 2022, at 13:30, michaeljtbrooks@... wrote:
?Full Instructable now available here:
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Full Instructable now available here:
|
Re: Microphone w/ built in compression? ¡°Lamplifier¡±
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Search for:
V-PROTECH Premium FOIL Thermal Emergency Blanket
For the UK:
https://www.amazon.co.uk/V-PROTECH-Premium-Emergency-Survival-150x100cm/dp/B09TRZT5T1
I deliberately went for the cheapest possible space blanket that said it was Mylar, under the thinking that this would be the thinnest material.
|
Re: Budget self-made condenser capsule (PCB based backplate!)
alloy foil from old wax capacitors as diaphragm. have used in home made ribbon mics.
toggle quoted message
Show quoted text
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..?
|
Re: Budget self-made condenser capsule (PCB based backplate!)
On Sat, Apr 16, 2022 at 08:11 PM, <michaeljtbrooks@...> wrote:
So, single-side metalised 6?m Mylar is available in sheets of 100cm x 150cm, (folded into 10cm x ~7cm rectangles) for a few pounds each. If you don't mind edge-terminated I can't imagine a cheaper way to make condenser capsules!
where do you get this sheet? I bet not all space blankets are the same and this thin.
|
Re: Budget self-made condenser capsule (PCB based backplate!)
I have small confession to make...
The space blanket I've been using is not 20?m thick as originally assumed. It is actually just 6?m thick! I got hold of a proper micrometer today and was able to measure it far more accurately.?
So, single-side metalised 6?m Mylar is available in sheets of 100cm x 150cm, (folded into 10cm x ~7cm rectangles) for a few pounds each. If you don't mind edge-terminated I can't imagine a cheaper way to make condenser capsules!
|
Re: Budget self-made condenser capsule (PCB based backplate!)
Brilliant!! That sounds much better than any of my home made capsules.
|
Re: Microphone w/ built in compression? ¡°Lamplifier¡±
> .. both are related to
electronics...
Yes, OT but related, Heathkit once produced a mod to the "Two-er" (and "CB1", "Ten-er" and "Six-er") which uses a Wheatstone bridge composed of two #47 bulbs and two 4.7Ohm resistors to yield a squelch that quiets the receiver's inherent super-regenerative hiss when no signal is tuned.
Tom
On Saturday, April 16, 2022, 6:51:40 AM EDT, Jerry Lee Marcel <jerryleemarcel@...> wrote:
I believe the only thing this circuit has in common with the
subject discussed here is that they both are related to
electronics.
Le 15/04/2022 ¨¤ 08:04, Andrzej Sochon a
¨¦crit?:
Hi,
I am sorry, maybe I do not understand an idea but, I found
something what may replace lamps: Vishay?
VO1263.?
Here is a link to the Mr?Scott Wurcer article
(diyaudio Forum): "My
version of the G = 1000 low noise measurement amp"
Andrzej
Buggy
whip with 56k modem, and tape backup..
I my very very humble opinion, I agree.? Think ¡°simpler¡± would
have been better (again, my opinion).? Maybe the inventor had
some goals in mind that I wouldn¡¯t have, don¡¯t know.? He also
co-invented the ¡°Sustainiac¡±, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb,
under-driven by phantom (and buck converter or something?)
modulated by a dynamic or piezo.? Maybe make it a stand alone
effect instead of ¡°in mic effect¡±. ? Just a fun experiment..
I would have been very curious had I seen my dad¡¯s Leslie
speaker cabinet glow more with the reverb! ?(I LOVED the
reverb, and everything else about it and the Hammonds he had -
except having to move them for gigs!)
|
Re: Microphone w/ built in compression? ¡°Lamplifier¡±
I believe the only thing this circuit has in common with the
subject discussed here is that they both are related to
electronics.
Le 15/04/2022 ¨¤ 08:04, Andrzej Sochon a
¨¦crit?:
toggle quoted message
Show quoted text
Hi,
I am sorry, maybe I do not understand an idea but, I found
something what may replace lamps: Vishay?
VO1263.?
Here is a link to the Mr?Scott Wurcer article
(diyaudio Forum): "My
version of the G = 1000 low noise measurement amp"
Andrzej
Buggy
whip with 56k modem, and tape backup..
I my very very humble opinion, I agree.? Think ¡°simpler¡± would
have been better (again, my opinion).? Maybe the inventor had
some goals in mind that I wouldn¡¯t have, don¡¯t know.? He also
co-invented the ¡°Sustainiac¡±, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb,
under-driven by phantom (and buck converter or something?)
modulated by a dynamic or piezo.? Maybe make it a stand alone
effect instead of ¡°in mic effect¡±. ? Just a fun experiment..
I would have been very curious had I seen my dad¡¯s Leslie
speaker cabinet glow more with the reverb! ?(I LOVED the
reverb, and everything else about it and the Hammonds he had -
except having to move them for gigs!)
|
Sey
Mic Scharf