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
Probably the best explanation of how a BBD works.
I feel like this video should count for credit towards an electrical engineering course... great work!!
Not enough linear algebra
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.
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!
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.
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 :)
I don't know if anybody mentioned this already, but I am pleasantly surprised by the little doodles and graphics present on the front plate of this new module =)
I noticed something similar on the panel of Labor already, and here it is once again with this new eurorack module. Little arrows and squiggles identical to the ones we see in the animations of your videos, Moritz. I really like them, hehe, they give the panels a personal touch without being distracting. Quite elegant too, I have to say.
I would like to see more modules in the future come out with front panels featuring similar graphical decorations. Thumbs up from me 👍
@@dr.getter7118 glad to hear, that was exactly the intention! and i do want to keep adding these to upcoming modules :)
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 📷
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 :)
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!
You Sir, have become a professional video creator in terms of content and quality. Kudos.
This is too good to be free on the internet. Outstanding.
Awesome sound demos at the end too. 👏👏
hey thanks, glad you enjoyed it ✨
Love this! Great explanation of how everything works, why everything works and in a lot of cases why something DOESN'T work.
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 :)
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 ?
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.
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 helped be better in my job.
Looking foward to more videos, truly
oh wow, that's great to hear. 🙏
Awesome video! Perfect amount of in-depth explanation yet keeping things easy to understand and consume. Great job.
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.
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 :)
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 😁
Your videos are such a huge inspo for me as a synth DIY geek. Amazing as always!
One the best channels on YT.
The obvious thing to do is to use more BBD chips for longer delay at higher clock rates. The clock rate should be more than double the max signal frequency. Then add proper higher order filters to get rid of all unwanted noise. So adding more BBD devices will increase delay at higher sample rates without distortion. Also one can tap signal between BBD chips for more interesting echo/delay effects.
CCD chips used in digital cameras work the same as BBD devices, but initial charge stored in each capacitor in line is determined by light level - it discharges them (IIRC). So process of getting the image data from the chip starts by clocking it out across the sensor to the ADC at the end of the line. In case of CCD chips propagation delay is a bad thing, causing horizontal tearing when recording fast movement.
Ah, then instead of modulating the clock rate, you can just manufacture more BBDs … no, wait, that's software thinking.
yes – but unfortunately BBD chips are really expensive. so this is not really feasible for a commercial product.
@@MoritzKlein0
Well, I found lot of ten for less than ten bucks, from China. These are clones, might not have the top notch specs, but are good enough for this usage...
@@MoritzKlein0it WAS done in various studio and broadcast kit though. Things got "very expensive, very quickly" in analogue designs
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 🙏
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!
What an epic overview! Well done!
Keep up the great content, Moritz Klein!👍
@@sjay4673 will do 🙏
Looking forward to seeing a mention of the classic MN3001 CCD bucket-brigade analog delay line chip from the 80s.
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
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!
Holy cow, the video production, the animation, and the crispness of the explanation... This is just fantastic. I might get into Eurorack after all with your "mentorship"... :D
you should, it's fun :)
Moritz Klein face reveal!??
No he has shown his face multiple times in live streams
hottie
I almost spat out my coffee
(even though I've seen his face before on his ig)
@borututuforte I know right?! Too distracting I need just hands and components or I stop learning. .
Jk Moritz. . Happy to see your smiling face. This made my day!
yes . a man from ww2
Such elegant explanation of a very elegant solution
Only halfway through, but this is looking remarkably like a synchronous dual sample+hold circuit I designed a while ago, designed to be a high-speed peak detector.
Also, with a 4046 as your clock source, you could make a comb filter out of it and use it as a VCF.
Best BBD explanation I ever seen! Thank you!
Pitch...swing ... CRACK and OUT OF THE PARK!!! Another brilliant video and teaching session!!! Well done.
thank you :)
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.
absolutely amazing, i always wondered about BBD and this explains it in the best way i can understand. thank you for making this!
glad the video was helpful :)
Great Job Moritz. And thank you for your videos that manage to inspire even the most experienced sdiy nerds, like me. big up for your work🎉
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?
I built a PAIA “Phlanger” in the late 70s with a bbd. It was quite effective.
Back in the late 70s and early 80s Radio Shack sold a BBD chip for projects. I built the standard one: voice actuated cassette recorder. When audio turned the cassette recorder on, the BBD gave the audio enough delay for the recorder to start recording so the beginning wasn't cut off. But the audio quality of the BBD was barely audio cassette quality. I recall it more like AM radio quality and I assumed that was the cost of using a bunch of capacitors to store audio. I was surprised to hear later on that BBD circuits could actually produce high quality audio.
that's a really interesting use case. maybe they applied really heavy filtering to combat the sampling artifacts and clock noise?
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.
Awesome work again Man.. Your way of explaining things is on point. !!
NEW MORITZ I CANT BELIEVE IT
OH HAPPY DAY!!!!!!!!!
loved it, thanks!!!!
This is DIY electronics at its best. Thank you very much for what you do, Moritz. 👍
thank you for watching :)
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!
Thanks so much for sharing your knowledge. Your videos really helped me get a grip on audio electronics and being able to breadboard stuff and modding some of my synths.
19:15 Neither my cats nor I appreciated this +8dB LU increase in loudness. ^^" (Perhaps 10dB lower than equivalent LUFS would be ideal for such a shrill sound.)
Great video though - I had never thought about the implementation details of BBDs before.
i am very sorry 🥲
@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.