Moritz Klein - 2024-10-16
Build your own Delay as a DIY eurorack kit: https://www.ericasynths.lv/shop/diy-kits-1/edu-diy-bbd/ LABOR in the Erica Synths Webshop: https://www.ericasynths.lv/shop/diy-kits-1/edu-diy-labor/ Support the channel... ... through Patreon: https://www.patreon.com/moritzklein ... by buying my other DIY kits: https://www.ericasynths.lv/shop/diy-kits-1/ Simulation in CircuitJS (discrete component BBD): https://tinyurl.com/2dbdonlb Join my Discord community: https://discord.gg/KCwpyAsFpb Here’s an interesting problem: how do you create a delayed duplicate of a sound without recording it to some sort of storage medium? Back in the days before digital signal processing and cheap, abundant memory, this was a prime engineering issue. Until two Engineers named Sangster and Teer came up with a deceptively simple solution: the bucket brigade delay. In this video, I attempt to reverse engineer the architecture of a classic BBD, recreate a bare bones version on the breadboard – and then use a proper BBD chip to design a simple DIY audio delay. If you want to build along, here's the bill of materials: BILL OF MATERIALS RESISTORS 2M2 x1 100k x8 82k x1 56k x1 51k x1 47k x1 39k x1 22k x3 10k x2 6k2 x1 4k7 x1 CAPACITORS 1 uF x2 10 nF x1 1 nF x1 (more if you want to build the discrete component BBD!) 220 pF x2 TRANSISTORS & DIODES 1N4148 (small signal diode) x5 J113 (N-CH JFET) x1 (more if you want to build the discrete component BBD!) POTENTIOMETERS 100k (A104) x1 100k (B104) x3 10k (B103) x1 CHIPS TL072 (dual op amp) x3 V3205SD/MN3205 (BBD 4096) x1 4046BE (PLL) x1 SWITCHES SPDT (Single pole, double throw) x1 Chapters 00:00 BBD Overview 01:43 Analog Sampling 10:09 Sample Transfer 16:28 Buffering & Listening 19:50 Dual Tap Reconstruction 23:01 More Stages with the V3205 27:55 Reconstruction Sampling 33:26 Dry/Wet Mixing 34:41 Feedback 36:04 Flanger Mode 41:43 Inhibit CV 42:59 Sound Demo & Outro
Not only from the technical perspective, also the filming, illumination, motion graphics, narration quality, used didactic tools... absolutely beautiful. This video is a piece of art
Really interesting as an audio programmer to see this weird transitional tech between analog and digital. Top video.
This is a higher quality explanation and demonstration than you would likely find in a university. Really nice work.
What I love about the BBD is that it blurs the line between digital and analog; Two things that most people consider to be sort of mutually exclusive. You get a quantization of time, but the amplitude is fully analog.
agreed – plus i love how simple it is, especially compared to something like a PT2399. BBDs really feel like a super precise solution to one specific problem!
Yeah. First it is analog, then discretized, and lastly digitized. This chip/circuit just omits the last step.
Lost me at dry/wet mixer 😮
Wait this isn't a fully analog circuit? Why?
@@robertosutrisno8604 it depends on what you understand by analog & digital. since a BBD is splitting the signal into samples, you can make the point that it is digital on the x-axis (time) – since the signal is divided into discrete blocks. the y-axis (amplitude) is still analog, though.
Man I wish I had this video when I studied opamps 30 years ago. All that abstract theory makes so much sense with a practical example like this.
Superb video - this is quality content that makes YouTube worthwhile. I've no desire to build my own BBD based delay, but learning how they work is fascinating.
@@chriswareham glad to hear :)
dammit I'm the other side of nerd, now there's a youtube video let's 'ave it, try and build one as well!! :P
@@MouldySoul that’s the spirit!
Probably the best explanation of how a BBD works.
Incredible video, can't believe information like this is available for free.
From engineer to engineer, thank you!!!!
I feel like this video should count for credit towards an electrical engineering course... great work!!
Not enough linear algebra
Yess
As a gear nerd who realised in the mid 80’s that not all BBD delay pedals were created equal, this video is fascinating.
sad4096 ?
What is crazy is the BBD is old technology now. But the analog nature allows for some charming quirks and actually great analog interfaces compared to microprocessor based solutions. Being that sound lives in the analog realm and the lack of code is great. An amazing build thank you
true, but as far as i know the idea lives on in CCD camera sensors 📷
...which have been almost completely replaced by CMOS image sensors today.
Thank you so much for this fantastic video. I'm new to electronics, but this has really helped me understand how bbd works. Your insight and ability to communicate a complex subject clearly is exceptional. I'm going to have a go at building this on a breadboard.
Thank you 👍
This is an AMAZING teaching video. I have basic electronic knowledge and understood everything. Even if you’re not looking at building a delay/echo system, there’s many basic electronics lessons contained in this video so it’s a good teaching lesson.
SO many instructional videos will just say "We won't do x because it causes problems." and move on. The way this video makes the problems happen and demonstrates why they're an issue before fixing them makes it such a great educational resource.
glad to hear, that’s exactly what i’m hoping for :)
Great video! Thanks for making it! I’ve built a couple PT2399 delays, but that chip contains much of the external components needed here. I had wondered why BBD delays were so much more complicated. For anyone interested,look up the data sheet for the PT2399, it shows a very basic delay that really just needs a voltage regulator,a couple caps, couple resistors, and a couple pots. It’s a fun and easy circuit to play with.
the pt2399 is extremely complex compared to a BBD chip - that’s why the driving circuit can be so much simpler :)
the PT2399 is notably not a BBD but in a way it's sort of the logical next step. turn the signal into a binary stream using delta-sigma and then you can use a really long shift register and cut down on how accurate/big the capacitors and transistors of each "stage" need to be on the die.
@@famitory yeah, I'm quite aware of that, but it's the only real frame of reference I have to compare it to. And while it is digital, it was designed to emulate the sound of the old bucket brigade type sounds. A lot of the control options are pretty similar too, such as being able to drive the clock speed with a modulated source, the raising and lowering of pitch as the speed is adjusted up and down, and the gradual darkening of the signal. It also does some wonky distorted sounds when you try to make the delay length more than it's designed for, similar to what he did in the video.
@@MoritzKlein0 exactly! That's why I had looked at BBD circuits in the past and had no idea what was going on 😁
I really appreciate the level of detail in your videos. I studied as an ME but my work involves a lot of EE knowledge that I've been learning on the job over the last couple of years.
The graphics in your schematics, specifing what chips you are using and why, and just explaining you're overall design process actually helps me be better in my job.
Looking foward to more videos, truly
oh wow, that's great to hear. 🙏
Excellent explanation of BBD operation, intricacies and 'pathologies'! Thank you for the fine detail description. Also, great use of PLL 4046 using all the internal functions, while NOT making a PLL from it!
One the best channels on YT.
This is too good to be free on the internet. Outstanding.
Awesome sound demos at the end too. 👏👏
hey thanks, glad you enjoyed it ✨
Your channel hits the perfect sweet spot of "technicality"! (At least for me - I studied EE/CS, but since college, I had zero experience with circuits and forgot all the annoying transistor calculations)
Still engaging, skipping on some of the unnecessary details and calculations, but not "dumbed down" and just perfectly enough to appreciate the beauty and smartness of those designs, explaining exactly what was challenging and how it was solved. :)
And while this might not be enough to build such a circuit entirely from scratch without your designs, it's again perfectly enough of a starting point if someone wants to dig deeper.
that’s exactly the balance i’m trying to hit - glad to hear it works for you!
Exactly, I teach analog electronics and digital signal processing at university and I'm always dumbstruck by Moritz didactic quality. I do recommend his videos to students and colleagues!
I totally agree. I haven't touched analog circuits since college as well, but found this super fascinating.
Sampling the signal again at the BBD's output is genius! I also love the creative front panel design. Amazing video and amazing kit as always :)
@@taidi4038 glad to hear you like the front panel design - thought it’s time the modules get some visual spice :)
What a lot of memories with BBD chips. Nice video.
Such elegant explanation of a very elegant solution
Love this! Great explanation of how everything works, why everything works and in a lot of cases why something DOESN'T work.
Best BBD explanation I ever seen! Thank you!
These videos are masterpieces not only of engineering but visualization and narration / explanation / education. Thank you. I bought a couple of bucket brigade chips to experiment with building a chorus effect pedal and was puzzled why the chip data sheet recommended use of a specific related timing IC. This explained why a dual clock source is required.
i think low output impedance on the clock generators is also important (cause the mosfet gates do pull in current when switching on). so that’s also why they made those special companion chips.
Just found your channel. Top notch teaching. I am now a subscriber.
As expected, another superb video from Moritz. I got just as much out of your knowledge of the PLL as I did from the BBD circuit approach. Fantastic. Thanks Moritz.
that PLL chip is seriously feature packed :)
I learned so damn much in this video, was just getting the hang of the basics of circuitry and this put so much of the basic knowledge into place. Combined with the real examples and argumented decisions at each stage had me hooked. Thank you for this!
Wow. I’m just getting started in learning electronics as it’s something that I’ve been interested in knowing how things work for a while and whilst I found it a bit difficult to follow along with at some points I understood the majority because you delivered the content very well. An outstanding video thank you for creating it. Now I’m going to check out your filter videos 😊
I’ve always wanted to design a BBD with a variable output filter tied appropriately to the clock frequency. This is a great point to jump off from and an amazing general learning resource as always. Thank you for your continued work on increasingly complex projects!
good luck with that project, sounds like a fun one!
I had thought about this with some variable sampling rate DACs too. It's on my "someday" list to experiment with adaptive filtering on the Sega Genesis PCM channel to settle the "muffled vs. scratchy" trade-off of different audio circuits used over the console's lifetime.
YES! I've been asking for a BBD video several times, and right as I wanted to try my own hand at it, a wonderful Moritz Klein video appears to help clearly explain everything about it! Thank you for these videos (and this one in particular)!
perfect timing - hope the video will help!
Reconstruction sampling instead of the traditional hardcore rolloff makes a huge difference in preserving the fidelity, and avoiding clock noise at very low frequencies. This means getting longer delays with smaller BBDs. Night and day... I'll definitely test this approach.
Thanks for the amazing explanation and presentation.
Amazing video, well explained and recorded. From the first half part, I learned a lot.
Just three notes:
1. You completely missed to mention the Aliasing issue, that happens when clock freq. goes below half the maximum frequency of the input signal (Nyquist-Shannon theorem) --> an input LP filter is really needed, tuned wrt the minimum clock frequency. Lot of the sounds of the video come from that fenomenon.
In other words, the bandwidth of the BBD circuit is always less than half of the clock frequency, otherwise you will get a lot of 'noise' in the audio band.
2. The two complementary clock signals need a small dead time between their edges (that is, there is always a short time when they are both not active); this is due to non instantaneous switching of the MOSFETs and will reduce a lot the spiking.
3. The flanger effect usually refers to delays that are a lot shorter (in the order of 1ms to 5ms) and the related audio effect is different from what is shown in the video.
Apart from these notes, I really enjoed the video and I thank you for such quality contents!
These BBDs were a huge breakthrough. I have a book that tells you how to make most effects with BBDs, not just delay. Flanger, chorus, etc.
what the name of the book ?
@@darmstard Wouldn't help you. It's long out of print and not in English.
@@CristiNeagu thank you anyway
just out of curiosity , whats the name of the book ?😅
@@CristiNeagu ok. what's the name of the book tho?
You Sir, have become a professional video creator in terms of content and quality. Kudos.
That was great. I remember seeing a 'Bucket Brigade' circuit published in ETI back in the late 70s I think. I had no idea at the time what it was.. Thanks for the reminder.
those ETI circuits were the basis for lot of stuff I built for friends
Really love these videos, can't wait to get my Labor here soon and start messing around with some of these edu-diy circuits
What a brilliant video! If I recall, there is another way that uses a shift register to generate a pulse that travels one by one from the output stage to the front in a rolling fashion. At each stage, the next stage is first emptied and then the gate is opened from the previous stage to fill the capacitor. This continues down the chain and then repeats. The output is a simple high impedance buffer and RC smoothing filter. Doing it this way removes a lot of the clock coupling. Anyway, absolutely brilliant stuff man, takes me back to my youth!! 🎉❤
This is just amazing. The video came out super clear and ultra interesting. By FAR the best one you've uploaded, keep doing this please! Thank you!!!
@@lucanotreally314 really glad to hear :)
Pitch...swing ... CRACK and OUT OF THE PARK!!! Another brilliant video and teaching session!!! Well done.
thank you :)
Awesome video! Perfect amount of in-depth explanation yet keeping things easy to understand and consume. Great job.
Your videos are such a huge inspo for me as a synth DIY geek. Amazing as always!
Great presentation! Got me reminiscing of playing around with the Reticon SAD1024 BBD chip back in the '70s for phaser/ flanger effects for guitar and vocals.
I am building guitar pedals, not eurorack, but still you are the most helpful resouce currently available and an endless source of inspiration. I have watched all your videos several times and each time come away with some new, deeper insight.
So thanks for making this available. Thats what i am trying to say.
that's great to hear 🙏
I have used many BBD chips in circuits along with synths, distortion, fx, for years, and I had a basic understanding of it but it's so cool to see one built from the ground up! Thank you for this great tutorial!
i was really happy when i managed to make it work using JFETs - so useful to be able to check the signal at every capacitor in the chain!
Cool ! I had a bbd it had mic and guitar inputs with volume knobs and the out ouput had a switch for different dB levels so you could use it like a pre amplifier. It had some mental sounds if you did too much feedback, it was quite hissy. I also had flanger and chrorus pedals before the days of digital delays. I had the first digital delay pedal as well when it came out.
Thanks!
thank you, much appreciated 💕
An excellent tutorial. Personally, I would have pegged Moritz to be noticeably older than he appears to be. So, kudos on being such an excellent teacher at such a young age!
BBDs contain the sorts of stages nicely illustrated here, but the capacitors they use to store charge for transfer, are also pretty small and leaky. That means that clock rates lower than a certain rate will result in enough leakage for the charge that gets transferred to be less and less like the original, the more stages it is passed through, and the more slowly it is passed from bucket to bucket. Ultimately, EVERY bucket brigade chip has a lower clock-rate limit. It also means that they do not and can not "store" samples the way that digital memory can.
But there are also upper limits to clock rate for every BBD. The input pins for the complementary clock pulses have their input capacitance. That capacitance tends to impact on the shape of the incoming clock pulses, when they exceed that upper limit, such that the "handoff" between complementary sections is not as instantaneous as intended, degrading audio quality. The Reticon BBDs had clock pin capacitances that were a fraction of those used in the Panasonic/Matsushita chips (and Coolaudio clones of them), making them more suitable for instances where one was deliberately aiming for very high clock rates.
The V3205 used here is a 2nd or 3rd-generation BBD. Earlier 30xx BBDs were engineered differently, and were aimed at higher supply voltages. The 32xx series will work with +5V. Why the difference? Remember that, in the earliest days of BBD-based effects/processing, while some effects had onboard transformers and a power cord, external power supplies were very much a rarity, and many effects pedals assumed battery operation. Since the DC bias voltage used to make the input to a BBD appropriate was taken from the supply, as the battery wore down, the bias voltage would change. The 32xx series allow the BBD to operate with supplies as low as +5V, even though the supply to the overall circuit might be higher. Regulating the voltage provided to the BBD down to +5V, and deriving the bias voltage from that meant that any pedal operating from a +9V battery would be able to function properly until the on-board battery wore down to around +7V. And by that point, it would probably be too weak to power the audio path and any LFO and electronic switching circuitry. Put another way, the 32xx series strikes me as really a solution to problems inherent to battery operation, and not an "improvement" to audio quality, per se.
Thank you so much for this video. As an amateur, ive been looking at how to fix an old dod rds delay, this gives me a better idea on how delay circuits actually work
glad it was helpful. good luck with fixing your delay!
@MrSlipstreem - 2024-10-16
I used to use high quality BBDs (clocked as fast as they'd go to keep the quality up) as part of an analogue signal processor. This allowed me to monitor and process a signal in real time a few milliseconds before it got to the listener. Using an analogue discriminator and comparator, it was possible to recognise a scratch on a vinyl record just before it got to the output and replace it with something else less offensive to the human ear. Another comparator tracked the average background noise level from the vinyl, so the system became fully automatic with no need for any twiddly knobs to adjust anything.
This was back in the late 80s, and I can still remember to this day the satisfaction of designing it all from scratch (pardon the pun). It took a few weeks to iron the bugs out, but the finished project still works very well to this day.
@Galova - 2024-10-17
Some BBD IC? Just curious
@MoritzKlein0 - 2024-10-17
@@MrSlipstreem sounds like a really fun problem to solve. what did you replace the unwanted sounds with?
@jameslynch8738 - 2024-10-17
@@MoritzKlein0He probably used anything other than the tone in the video at #19:20 😉
@MoritzKlein0 - 2024-10-19
@@jameslynch8738 🥲
@gorloxian - 2024-10-21
Dude you old analog guys, I am in awe of. My "artist" name is a term from an exotic quad decoder.