This series is awesome because Doug knows what he's talking about.

Damn this video just opened my eyes. I have a pair of NT3s, and i always hated that bump, and eq-ed it out. First thing in the morning i am getting my soldering station and getting that part of the circuit out. Thank you so much!

What a privilege to be able to watch an expert explain the reasoning behind their thinking. Excellent content!! Thanks Dave :)

I hope that all of us that are following Doug Ford's wonderful explanations, understand that this is a one-in-a-million chance to learn from Doug's career. Try going to Rhodes or other manufacturer and attempt to get them to teach you these trade secrets. You couldn't pay enough to learn any of this. With what I have learned, I could go into the microphone manufacturing business (if I wasn't retired). I once had the president of a company, say, "Anyone can see what we did, but the hard part, is learning WHY we did it." Thanks for taking the time to create, edit, and upload this material to KZfaq.

Exellent series Doug and Dave. Thankyou, most entertaining and educational. Rhode might be a bit pissed though seeing all their trade secrets explained ): Doug is a real character

I have an original Rode NT1 (battleship grey version, not the 'A' model), best mic I've ever owned! Great to see the designer behind it and the genius in design. I'd love to see more pro-audio related videos on EEVBlog!

20:59 "Distinct preference" Doug Ford is an absolute genius and EE rock star. I've probably watched this series 134,789 times.

That was so cool!! When he spoke of a -120V FET, the first thing I thought of was a tube; I fell off of my chair when he actually said it.

As an EE you should really appreciate the work that has gone into this. had to watch it several times to get some pretty darn good jewels out there.

This is a fantastic series that I had not yet seen. Doug is a good teacher, and his designs are very interesting. Also interesting to hear about production issues/cost savings, etc. Thanks.

I looked at an NT3 frequency response curve just now and sure enough, there's a bit of a whoohoo! at 6kHz

I dont know why in the hell im just now seeing this but it is awesome. Some of it is flying over my head at lght speed but im determined to be able to do this before im dead. I would love to see more of this type of content. Just designing different things.

I've watched EEV Blog for years but this is by far the most informative video I've seen! Thank you! Lots of great stuff in this one! Thanks Doug and Dave!

Dynamic duo. Bring Doug back. This was informative and fun.

Would love to see more videos with Doug. He's a class act, and analog design is a great subject. How about designating a day of the week as "Doug Ford Day"? :)

I really love this series. I'm familiar with Rode microphones, and it's really cool to hear Doug talk about the designs. Thanks again Doug and Dave. Really awesome.

I watched this video before and after taking my first VLSI design class. After learning to design Opamps from Fets everything in this video makes sense. This might be one of the best displays of a good/real design process on KZfaq, everything is organic and logical

This series is a classic in the making - simple as that. Make sure you back up these vids for posterity

polyputhekettleon caps - i hear those are popular amongst the audiophools.

I think I've watched almost all the videos, but I skipped this series about microphones. But as usual, now I'm very interested in microphone techniques, and this is a gold mine! Thanks, Dave, yet again. The KZfaq channel that keeps giving.

Yupp, disconnected T bridge network, this is one hell of a mic now (even tho it was that allready, but less sibilant now). I'll have to do a tutorial on that.

Years and several hour-long web searches later, and I think I have found Doug's jFET. Only match I could find is the Solitron FND15. Not a very common part; and I couldn't find that particular topology built from discrete components anywhere. CIA, you say? A conspiracy theorist might suspect that defense contractors have tried to redact all knowledge of this chip. By the way, we haven't heard anything from Doug in quite a while...

thank you for this high quality, free and enjoyable education.

This video is incredibly educational and well explained in such a way that I enjoyed watching. Thank you for creating this. I designed my own preamp / mic processor and ribbon microphone from scratch and it's nice to see youtube has some videos out there like this to help people learn right from the source.

Fantastic video series! I wish I had someone like Doug as a mentor.

Ok, so now I added some R0DE mics to my amazon cart :-) Thank you for doing this, and please more content like this. I really appreciate the deeper dives into practical analog

I love Doug's manner of speech...very interesting...I could listen to him for hours

you should have him come back for more lessons! turn this into a permanent thing?

another great Doug Ford video... could listen to him talk topology all day.

Can someone please give Dave some good whiteboard pens in the next mailbag!? :D

Definitely not 101.

I love this video. Not only does it have a highly informing value, but is also very entertaining.... especially when the two of you have a great genuine laugh about them silly mic customers demanding more excitement in the upper range. I would say that many artists have way too much excitement in their own upper region (brain) anyways. Thank you for this great video D^2.

This has been a fantastic series, Dave. Hope to see more from Doug in the future. Maybe you could get some other designers from other companies to discuss the products they've worked on too?

I've zapped my lips a when using my first DIY valve amplifier + PA not sharing the same ground. Apart from the groin and heart, I think that's the worst spot to get zapped. It was the fastest lesson ever learnt.

+EEVblog Doug is just awesome, I hope we can get more videos from him soon.

I enjoyed learning about the construction of the NT1000 as I've experimented with it before, very easy to make recordings at low volume with this mic, and hardly any gain needed. Now I know why!

How did I miss this? Amazing info download from Doug, thanks for bringing this out for us to learn from. Fantastic.

Nice Doug! Feels like a lost art these days though. I appreciate your time though. Thanks.

Great tutorial. I haven't designed (active) analog circuits since college.

I went to Sydney uni electrical engineering, we did some basic opamp stuff, I wish we were taught more practical designs and testing. We did more maths with pen and paper and maybe some simulations. Thanks Dave!

The pure enthusiasm and inside jokes are really nice to watch! Now if I could only understand what they're laughing about... Maybe one day.

I have an electrical engineering degree and just learned more in this video than all of college

huge audio enthusiast here so this content with Doug I'm vibing with!

'tis always good to hear why something was designed a certain way, not just how it was designed.

Most interesting thing I've seen all week. Thanks Dave and Doug!

It's very interesting (comical) watching a couple EEs at work. Very good!

15:58 "Connected to a sig genny" is the most Australian EE colloquialism I have ever heard, fantastic.

I'm two years into my elec engineering BS and when does it all click like this?

The one thing I don't like about Dave is that he tries to finish everyone's sentences to show that he's aware of the topics too. This may be due to an insecurity about where his knowledge level is. Other than that, great stuff.

Please, more of these vids with Doug!

13:20 Damn I actually went back and set up my EQ like that to listen again and it really made it sound a lot more like pop music lol. That's amazing

wow .... such a great time to have all that knowledge in reach by some clicks I want to build my own preamp now :D oh and thank you so much EEVblog

Do white board markers ever work properly? This video brought back memories of lectures in the 90's when lines were drawn, then drawn over again because they were faint, then drawn over a third time before the lecturer said "@#%& it" and threw the marker in the bin. Every lecturer saw two or three white board markers hit the bin :-)

Wow Nick, I needed this video, I have a ubit Xv6:2, the mic is the part I'm not happy with, the audio pre amp and compression, is the other part that, and here it is all together. Marvellous thankyou Nick , Paul M0BSW

Solved my problems about initiating a design from scratch! Thanks for that 😀

There is a simple trick to reduce the noise figure. Simply add a voltage divider on the output. Your 12db noise figure will drop to almost nothing.

That was awesome, I need to rewatch and take notes!

We want to see more of Doug Ford.

+EEVblog Could you make a video, explaining this video for ... amateurs?

"Did you stick one until it works ..." Dave, please don't give away the most important trick in electronics design!

My god! I would love it if an engineer would write "more excitement in this region" on the data sheet. I dont care what kind of device it is, but thats something that needs to be in a datasheet :)

why not use an opamp instead of designing a unity gain power amplifier with jeft single ended input?

Absolutely gorgeous 💕💕💕... No other can teach us like that

Thank you both ,I love mic design series

Your best video yet. But i cant stress enough: your trade is a SCIENCE. Recording music is an ART. If your favorite songs were recorded with flat freq response mics and everything dead flat - quite simple they wouldn't be your favorite songs any longer. It's OK... we laugh at product engineers and electronic technicians also at some choices made. That guy in your video (ex-Rode) is an absolute genius. I use both the NT1K & NT3 every week! Great mics are some of the others made by Rode. Lately seems they are to focused on consumer level goods however - worryingly.

Love this. What a bromance.

learned alot from this series. Thanks. I like to tinker with wide band audio in CB communications. Now I have some better ideas for mic preamps and mic choices.

Very interesting, great content. Thank You!

Analog design is a lot of fun!

great video, I didn't think you would ever use a power amplifier in a preamp, very interesting topology.

What a beautiful mind. I using rode microphones in my studio btw. Thanks for very interesting topic and some topology suggestions, very exciting. Especially at the hi end of frequency response :)

14:33 Amateur question, why don't they add the different transfer wobbles with EQ? *presses play again* Oh, I see. So it's really just the "buy more stuff and show it off" drive.

Very useful! Convinced me that I don't want to do analog!

I still don't understand how to use BJTs because of their nonlinear behaviour. It's confusing. I am going to play with some JFETS or MOSFETS, because of their more linear response. (Mind you, my background is from mathematics, so I want things that are more ideal/linear.)

damn you and thank you very much for dominant pole compensation, i have a failed guitar amp that i could not troubleshoot; analogue audio amps were glossed over in college

I just love watching this

wow this is real interesting, my favorite thing to learn about is microphones. its the most interesting component in the world

24:37 : 600 ohm loads: because sometimes you want to drive the house.

I'm a mining engineer, I'd love to see a very low frequency mic schematic or a tweak to one of those mentioned that allows for very low frequency pickup.

That's an old but nice one with a real deal mike design pro! Very interesting and enlightening. Makes me wish I could work with Doug and learn tons of cool stuff he knows. 35V RMS? Then you just put a step-down transformer on the output, but then I'd just o for an all-tube construction putting the transformer in the plate circuit. I bet a low-noise +48V to filament and plate converter is perfectly viable especially if you go for a hybrid design where the tube (subminiature, preferably) is there for specific distortion rather than being an amplifying workhorse.

Look at him and his love for circuits

Great stuff, guys - really fascinating stuff.

Dave, I know this is a bit offtopic, but check out this alternative uses for a scope people are coming up with these days, Beams of Light by TRSI

EEVblog, and I'm SURE you wouldn't mind a few thoughtful people "borrowing" that low noise power supply configuration (around the 30 min. mark) for a modern preamp... would you? LOL

Very nice and informative video.

Thanks for these vids on Microphone Technology Amazingly Interesting :)

I'm with Dave. As an engineering "purist", I'd suggest a flat response at the preamplifier and let them boost treble at the mixing board. That is ... unless that preemphasized response were part of an accepted industry standard. (Or at least make it switchable for customers who DON'T want it.)

I have a lovely pair of factory matched Rode NTK mics.

Legend - amazing knowledge, thank you :)

Very informative! Hilarious as well.

In the circuit at Min 4:00 the FET would get a 90V spike impuls over the 50pF capsule in the moment when it is switched on. Will the FET survive this?

SPIN A YARN WITH DOUG ON THE AMP HOUR PLEASE.

This video helps a lot, thanks!

I find a very low resistor on the emitter of the top pnp going to 15V can sometimes increase stability quite a lot..

7:16 best moment imo change my mind

If that's his pre-amp design, I want to see his power-amp design!

very interesting... Ive soooo much to learn!

When you run a dynamic mic with the phantom power on it can be hard to sing. Happened to me on a mixer that could only have phantom on or off for all inputs rather than individual inputs.

This is a really rude (in a positive way) concept. Simplification to the maximum ! To understand this thing correctly: It is literally a current feedback amplifier with a negative input bias on the negative input terminal due to the voltage drop over the jfet (which does not matter here, because in this case it will be input- and output coupled by capacitors) A friend of mine introduced me into this concept, who has lots of try-and-error-experience in building amplifiers, but sometimes does not fully understand, how the things work. I help him a lot disassembling his amplifiers, reflecting what happens in them, etc. He used a feedback resistor of 10kohms and used the 1kohm in this schematic as output-offset-trimmer, which is really interesting, because this way he literally build an operational amplifier, which has 1) a big negative bias on its negative input port and 2) has a continous current flowing through the feedback path, but 3) no output-offset, in his case WITHOUT input- and output coupling caps. Long story short: I expanded the principle by a current source below the input-jfet to remove the negative input terminal bias. This gave us the opportunity to set the feedback resistor and by means the open-loop gain. Nevertheless, if you can deal with the bias-thing in the back of your mind, this is one of the best sounding pre-amplifiers i've ever heard. Really really raw and pure, due to the minimal usage of parts, but also very exact, because of the possible high open loop gain. The key is to choose the right transistors on this on: In my final case, as input transistor, i use an LND150 depletion mosfet. As amplifying transistor a TP2540 from microchip does a great job, and as puffer output, a pair of TN2540 and TP2540 were used. This way, the amplifier only contains MOSFETs (come on, some voodoo plssss)

@EEVblog: Even by watching the video again (don't know how many times) I can discover some new details again and again! I also liked the frequency with the little more "woohoo" very much. :-D That kind of videos are very interesting and very well in teaching electronics basics and circuit design - wouldn't that be good to have some more of those type of videos? Maybe (if you are allowed to) some more out of your field of operations back from your days at other companies?