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- Опубліковано 13 тра 2014
- Doug Ford, former head designer at Rode Microphones explains 48V phantom powering of microphones and how it works.
There is a ton of stuff here:
Electrostatic and electromagnetic noise, differential amplifiers, common mode noise, transformer magnetisation current, JFET differential driver circuits, balanced impedances, phase splitters, miller capacitance and how it matters, and he explains how the Schoeps amplifier topology works.
Forum here: www.eevblog.com/forum/blog/eev...
All the videos in this series with Doug: • Microphone Technology ...
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Fantastic having an explaination of microphones directed at engineers rather than musicians. I would love some more on amplifier circuits in the same way.
Ahh....now it all makes sense. So all the Elvis moves on stage were involuntary electric shocks! :)
Made me think of Elvis too when the engineer acted out that scenario!
Having Doug on the show has been a great addition to the eevblog ever since the start when you were blowing up cheap-ass multimeters together :-) I think the microphone series is very worthwhile because i knew quite little about it before. Keep it up Dave & Doug!!
I remember when this was published, it all was Greek to me, and probably I half-watched it. Now, because of the EEVblog, and other inspirations like Fran and so many, many who stopped doing videos long ago, for some reason today this series was in my feed and it was like a revelation! Wait a minute - I can do these things, now! I can build it! I have the technology! Thank you Dave!
I loves Doug's little jabs at the audiophile market.
You mean audiophool market :-).
You know what they say about fools and their money.
a good dac and amp is nice but prices like 400 dollar are unnecessary and retarded. with that said I have to say onboard motherboard audio is most times, total crap.
Lan Party Hosting I would agree that those Audiophool Grade DAC and amplifier are total waste of money. But I don't know what 'crap' a onboard motherboard audio would be, since they sound pretty decent to me, as long they don't sound like a $10 radio speaker.
Most modern computer have decent onboard sound,even my 2yrs old laptop do support 24bit/192khz sampling rate. What you need more for a 2 channel Stereo sound?
Bernard Lim its not about the bit and sampling rate, most times the dc to dc converting power supply on your motherboard to power your cpu generates noise which gets coupled into the audio mixer making it sound noisy. Sometimes the microfon signal even gets coupled into the speaker signal or vice versa. meaning that you can hear yourself talk, our your friends hear themselfs / your music. This happens most commonly on cheap motherboard brands like asrock and aopen are worst in my expierence.
Lan Party Hosting For your case it's not the Dc-Dc supply problem.
you can try goto windows control panel > Microphone properties -- Uncheck "Listen to this device" that's a feedback feature when you have MIC plug in. If not a Noise-Cancelling Headset would solve your problem.
Thanks for getting Doug to do this series. This is my favorite so far because I have always wondered how phantom power works.
The learning never stops. Wished I took up sound engineering when I was in college. Thanks Dave for the series. Think you've hit another goldmine.
Microphone design has proven to be a really deep and rich subject, even at a "basic" level!
I love watching this series. As an audio engineer, it feels good to have a chance to go over the basics again! Also great to introduce newbies to audio engineering and electronics. Cheers for the uploads Dave.
These videos are brilliant and exceptionally helpful. Doug's passion for his craft really shines through. Id love to see more of these videos. Get him back in the lab!
Find those videos very interesting! Thank you a lot Doug and Dave!
I think this is the most engrossing video you have done yet Dave. You should get guests on more often. The years Doug has put in really show in the passionate way he talks about microphone design.
Great Series, I hope you get the next/last part uploaded soon.
Great series. Keep those mic videos coming :)
Wow that guy knows so much about microphones. Like he must be the guy that everybody consults on microphones.
I hope dough got a good few pints for this, very good series so far!
Thank you both ...
Thanx again guys! I love learning about the innards of my every day tools. :-)
Doug Ford is my hero!
This series is awesome!! It would be great to have a mic preamp specialist (Neve, API, etc) and other music electronic specialists to explain gear, circuits, and debunk myths
Even though I'm a mechanical engineer (well, almost) and know close to nothing about electronics (hope to change that), I still enjoy watching this series. It's entertaining to see how a person who knows a lot explains it in a witty way.
Man i love this series!
this is such a great series
won my subscription on the first video I've seen! love how you describe things.
I am an audio Engeneer student, This stuff is awesome!
Whoa this video is a real eyeopener for me. Great Vid!
"Nobody likes transformers these days" - yeah thanks to Michael Bay!
When this first came out I couldn't watch it, I just couldn't follow along. I still can't really, but I understand some of what is being said. Here's hoping that in a few more years I'll learn enough to really appreciate this!
Great explanation. Great people.
I must say I'm not really inito microphones, but I actually like this series. That's because Doug gives so detailed information, real-world examples and really covers a broad spectrum. I'd like to see a series on ADCsDACs/OpAmps/other building blocks of electronics. Any chance Dave will produce some hour-long FUNdamentals friday videos in a similar fashion?
Thumbs Up!
Great Series.
I guess that this is also how the twisted pair cables work in an internet LAN cable by also using the instrumentation amp or some similar principle? I pity those who nag that the topic(video) is boring as their own field of knowledge is short and they can't see connections to different things. Thanks Dave! I did not give any interest in mics before but I see that it benefits greatly in my general knowledge :)
I think there is lots of good stuff in here besides micophones too, plenty of circuit detail that can apply to many things.
EEVblog yah the whole twisted pair - i always do that anyway for protos... it just looks cooler. i really didnt know it was 'better' (for some things). but after this video - yah, totally makes sense.
EEVblog There sure is. I'm working on analog synth stuff lately and this series is giving me lots of ideas
Ethernet, ironically, uses transformers. At the frequencies that ethernet runs at they're cheap and small. And the isolation is pretty nice to have. They look a lot like a black DIP chip on a NIC.
Kevmatic22 Yup, and there are two transformers on one end and they are now even in tiny IC package or even integrated to the LAN sockets. Check hanrun HR911105A for example
Looking forward to the next video..
I really really enjoyed this.
love the puffs...
Please show more things like this!
Can you build some prototipes to show how it works?
It could be more like the regular stile of this channel.
¡¡¡Beauty!!!
I still love all this mike lore!
I didn't understand about 90% of this but I still thought it was great
Watch it twice! Once for actually hearing what they're saying, and the second time enable the automatic english subtitles. I laughed so hard, my wife came to check if I was alright :-)
UA-cam subtitles of aussie accents are always a hoot!
very funny with captions, sounded like an attempt at a disguised illicit phone call between two people into some very weird activities.
"...not being stressed by any DC magnetize Asian..."
That is just sooo wrong, UA-cam! :-)
"...the two round ass secretary which we then..."
Dave, what on earth were you two talking about? :-D
I'm at 8:38 and trying to figure out how the source impedance for the S (assuming source on bottom, drain on top for this JFET) is lower than the source impedance on the drain. We're talking about from GND and VCC, right? I'm definitely missing something here.
EDIT: The only thing I can figure so far is that this is actually a common-source JFET amplifier with the capacitor shunting the low-side resistor there to ground. Or, arguably he mentions there is more capacitance gate to source than gate to drain(later). That could definitely unbalance it, guess I assumed it wasn't that big of a difference at the frequencies we're at. And he seemed to act like it wasn't the same thing because they were separated by time he got to it.
I always wondered about this.
good explanation. Cough is bad matey.
brilliant idea to invite head designers from different companies.
I want to see a balanced topology microphone!
Just get your own copy of: "Dickreiter, Handbuch der Tonstudiotechnik, Band I und II" it´s all in there in clear words, just like this series, and a *lot* more...:) Sadly it seems to be in german only, nerver saw a translated edition, jet.
I wonder if Dave learned beauty, puff, and other expressions from Doug.
Nice tricks.
7:00 why is it capacitively coupled to the opamp? What are those caps for?
9:48 Aren't pins 2 & 3 touching, effectively shorting out the microphone?
"Let's have a look at balanced topology amplifier" What a cliffhanger !!! More than 5years later still waiting for this one !
Great series of video by the way, it's at least 3rd time i watch them all and each time i watch again i still learn few new things. "that's... brilliant"
Any plane to have Doug Ford back ?
Dont know what they talk about but its relaxing :)
18:00 Could someone explain? Why "typically electrolitics" and not film caps for signal path? Is it still about costs and good enough or there is something about ECAP characteristics suitable for this application?
How does the single that single ended preamp give us a balanced signal? The ground has me lost! (19:12)
If I use a 48v mic wireless mic transmitter for my condenser mic to audio interface, would it deplete the quality of my mic... is it also liable to pick up unwanted sounds?
Nutrik for your XLRs.
What a tease ending as always... just about to get into some more details and BAMM!!! Nothing!!! :-|) Thanks for sharing as always. Way neat video and looks like a series I'm going to have to watch now that I'm looking into expanding up to 192kHz monitoring without aliasing with a 384kHz SB G6 USB sound card. Wondering what other ways there are to monitor into the ultrasonic range more effectively? Definitely have more than Bat's, Rat's and Mole's around us.
Are you sure you have to connect shielding at both sides of the twisted cable? I heard it's not good.
For mic cables, yes. The connection of the shield to the mic chassis helps shield the mics circuitry from noise. It is sometimes recommended that line level interconnects have the shield connected only at one end to break ground loops. This is likely what you are referring to.
@@chrisbauer1925 Thank you!
Cool
Now it make sense !!
I have Behringer c1-u USB microphone, which has quit low volume output.
Is there any way to get phantom power into it ??? or make it output more volume ???
Not really. Yours is a USB mic, not an analog mic. It solely draws power from the USB port for a fixed-gain preamp and built-in ADC. Most likely you have a driver or software issue. It is faintly possible that your USB host cannot source enough current for the preamp (in which case, try a powered USB hub).
edit: apparently a common problem with that mic. Poor design.
Did you try to adjust the recording level in the Windows Volume Control
panel? right click on the speaker icon in the task bar then select "recording devices" and go to your mike properties.
Thanks guys. I know USB doesn't have phantom power, just wanted to know is there any alternative way to get it louder.
DolganoFF Ya I increased the volume level and thats how i have been working with that mic. But still I feel thats not an efficient way to get a good volume.
vaidhya nathan If you still have gain left in the mic adjustment parameters, crank it up! And if nothing helps, well, you'll have to get another microphone I guess...
Does the circuit at 9:50 have some name by which I can google it? There's one thing that I can not understand about it. Okay, we have the collector voltage fixed, good. To be able to work in the linear region, transistors need some voltage headroom between collector and emitter (determined by base bias voltage). Well, by looking at the circuit, one can deduce that this is provided by voltage drop on the base resistors, so collector-to-emitter headroom voltage becomes
Vce = Ibase*Rbase + Vbe
From this, it is natural to expect that when the AC amplitude of the input (base) voltage exceeds this value, we must hit the collector voltage (fixed by zener diode) and the waveform should become distorted. I.e., it seems that the maximum input/drive amplitude is set with base resistor and transistor beta.
But SPICE simulation shows that this is not the case! When the input voltage amplitude exceeds base resistor drop, the DC offset at emitter magically shifts to accomodate any AC amplitude, and the real limit is
V_ac_max = Vphantom/2
And no limiting at all (until the signal hits the rails, of course)! How this is possible?
Moreover, it can be seen that when AC input exceeds the above mentioned limit (Vbe determined by base resistor), the voltage on a zener diode actually dips to accomodate the peaks. So, in a sense, AC amplitude limit is actually defined by base resistor voltage drop if we want to have stable power to our curcuit, but not in an expected way.
Actually, this can be fixed by adding a separate zener diode for the base resistors. I.e., if we disconnect base resistors from the collectors and connect them to a separate zener diode having a greater voltage than the collector zener diode, we'll fix the common mode voltage at one level and collector voltage at the other, providing defined headroom for a signal and stable supply voltage at collectors.
How can the Schoeps-type preamp voltage swing capability be increased? I have a Chinese copy which clips if the singer goes anywhere closer than 2ft from the mic! Can the output transistor collector-emitter voltages be increased by increasing the value of the base-collector biasing resistors?
next!!
Transformers may be bandwidth limited but don't they still have enough bandwidth for the audio range?
I don't get how ground creates a balanced signal at the end.
i love you guys
:)
So.....what microphones should I buy?
The ones Doug designed at Rode of course!
+drumrboynoid i'm very happy with my NTG-3 :)
So, if i understood. In theory, dinamyc Mics are not affected by phantom power
Does anyone here know that Doug Ford is also the current Premiere of Ontario
at 15:33 does Doug say "Wanker market" ! ? haha
So if I buy a XLR Microphone, get a phantom supply, buy two XLR cables and a amplifier it should work? Would be great if you could reply, this is hurting my brain.
Dear friends... Basic question.... I have a Korg Pa3x keyboard and I want to use a head worn mid-priced microphone so that I can sing with my hands free whilst playing. Is there any specific microphone that I ought to look for if I wish to just directly plug the 3-pin XLR mic wire into the back of the keyboard without opting for wireless receivers and so on. Also don't know if a wireless receiver set-up could be connected directly to the keyboard or not? The Keyboard has got its own Speakers amplification interface and vocal processor built-in. Many Thanks in advance Raddis from UK
I think Alexander Graham Bell used the principles shown back in 1876.
Get that man a drink!
At the end, what does he say? A balanced what amplifier?
Mr. Ford: "Let’s have a look at a balanced topology amplifier."
The Crazy Aussie guy: "Let’s do it!"
At least that is what I heard... Cheers!
FreiherrMannerheim
Thank you! :)
Where is the next video
Doug ford i think work for Jands electronics
The wanker transformer market. Priceless! Great video.
Why doesn't Doug have a youtube channel? :D
He's a luddite. He's only recently gotten a shoe phone. Give him another decade.
This guy should teach engineering somewhere
Wanker market - yep, too many of those in the "sir didn't pay £10k+ sir isn't professional" - yeah, TV production i'm looking your way!
Same for sound production!
Having "right name" branded equipment magically makes you better professional :)
DolganoFF 1) Buy "right name" stickers from ebay 2) Stick them to your t.bone mics 3) ??? 4) PROFIT
SakariNy there's better: buy knock-offs from ali express with right stickers already applied :D
I dont know how good are you on designing but definelty on drawing....
I mean in left side you stubborn continue squeezzing components and also telling its gonna be hard to fit instead redrawing the schematic so they can fit
screen is a faraday cage
f*ing puff xD Is it a Farad?
Joe Khoury
1 second ago
I'm a DJ, and run into videographers wanting to connect into my mixer. I don't have issues doing it. The problem occurs when they connect to the back of my speaker. It either lowers my output, or basically shuts off the speaker. I believe it may have something to do with phantom power perhaps? Is that something somebody here can explain. I don't have an audio receiver, but is there a setting to turn off phantom power?
I am from New Zealand so I am only watching this to laugh at the Aussie accents.
Narhh, not really...
I knew a fella with $100,000 dollar set up in his house. Giant horns built right into the walls, ultra-snazzy tube gear, etc., etc. I asked him what he listens to on this system of his. Thrash punk music. Nothing else. Yikes!
How many of these videos are there? Mics are interesting, but not that interesting.
Then don't watch them. Would you have complained if I had uploaded nothing at all today? If the answer is no, then you shouldn't complain about this video. I shot several hours of material with Doug, so am breaking it up into useful chunks.
EEVblog
Hopefully there is more, it is one of the areas where there really isn't much information available beyond overgeneralized things, especially when it comes to mic design. Compared to other industries, many microphone companies are more tight-lipped about about the inner workings.
I think people who watch EEV blog are a little more interested in substance than a quick overview. I for one am rather happy with knowing more about microphones than "they turn sound into electricity!!!
Now i want more about FPGA's
EEVblog
Don't mind the naysayers. I've been enjoying these. More interviews and whiteboard "design principles" videos are welcome.
Here is an absolute expert presenting his incredibly deep understanding of analog electronics. And better yet: He's doing it for free! I'm sorry to say it, but everyone who is complaining about this has to learn one or two lessons about life yet..."Undank ist der Welten Lohn".
Like the vid but don't like doug's way to talk about other countries and its marginal markets. You can still learn things from the ones you think are hopeless.
Ok so how do you connect a phantom powered microphone into your soundboard that's all I wanted to know what a crock of yak dung are you talking about.
Why not just watch some other video instead of insulting? Just because you don't feel you need the information here or don't understand it, doesn't mean this video doesn't have value to other people. Insulting it is just plain dumb.
the title of the video is How Phantom Power Works not How to plug Phantom Power Mic to a Soundcard that's the crock why.
Your English style is odd. Its not American nor British.
Like the circuit, just the same.
You just eat the time to technical bullshits to straight forward avoid the REAL knowledge!! Explain it simply and all will be understandable. We have a cable with two conductors and one ground .With dynamic mics has not a short circuit to need power to works and with condenser mics we have a power amp inside that it needs power to work so we need phantom power!! Thats it!!! WTF! You just do it to blow my mind!!!!!
I dont know how good are you on designing but definelty on drawing....
I mean in left side you stubborn continue squeezzing components and also telling its gonna be hard to fit instead redrawing the schematic so they can fit