PT2399 Delay Pedals - How do they work?

[@danielcollins6195]

The circuit walk-through without getting bogged down in math is great. And having the math in the build doc provides a nice balance for people like me that like the math.

[@lordflatworm]

Your glowing sock toe is a groovy visual for these trippy riffs. Btw this channel has made many many things possible for me. I can’t thank you enough.

[@melbournemudmetal]

If I'm ever looking for a video on a new area or aspect of the universe that is pedal build and design, I'll always watch yours before going any further. I find them perfect for grasping a basic understanding of new concepts. It sits in what I call the "Goldilocks" zone of information; Not too heavy, not too lite, just right. Works well with my, "OK, hurt me, but just a little" attitude towards life 😛 Being a fellow Australian help, too...

[@zachary963]

I honestly can’t wait for y’all to come out with a chorus or flanger pedal. Your videos explain everything so well

[@erikvincent5846]

We have the Lich King Chorus which we did a video on a bit ago. We have a flanger in the works

[@zachary963]

@@erikvincent5846 just saw this! Thank you so much!

[@jamesjakeway9839]

Thanks for the walk-through. I do like the high level explanations of the elements within the circuit. It frames math in the build documents helping me getting into the specifics quicker.

[@calinguga]

very considerate of you to block the led with your toe.

[@finonomastropiero4261]

Indeed

[@dr.diegoarredondo3893]

Amazing video. Internet needs more of this, sharing real useful knowledge. Congratulations!

[@CarlTelama]

Great video. Hadn't been getting a huge heap out of the channel because I had "graduated" to building slightly more complex circuits but this entire presentation style had me hooked. Thanks for your efforts Eric and Paul!

[@maxonmendel5757]

Erik Vincent, thanks for such a great circuit! I am working on modding a pt2399 delay i have so it is up to spec, and then circuit bending it to get the topology right.

[@stefanhansen5882]

This was absolutely amazing! Just getting into this DIY. Can you recommend a book or video which will explain the basics, maybe how a filter works, how a buffer works, how a gain stage works, or something like that. Whatever you think is good to learn about first. Thanks!

[@LitesLAB]

This was great fellas! Keep these coming ... one suggestion, it would be nice to see you build the circuit ... showing the effects of changing the component values, like you discussed. Like the older fellas say, the “traps for the young players”.

[@Jack-hy3ye]

These circuit analysis videos are great, thank you!

[@octopus-tuxedo5456]

This is 👍 I am building my first pedal and it is a dual granola and delay pedal. I just got done with the Franklin part and starting on the delay now and so this video coming out at the same time is sweet. This channel has really helped over the past few week as I have been getting into this hobby while in quarantine😷 so THANX😀😁 DIY Guitar Pedals

[@maxonmendel5757]

granola?

[@kirabarsmith9353]

I like PT2399 delays more than DSP and BBD based ones, such an incredible sounding inexpensive chip.

[@DiyguitarpedalsAu]

An amazing sound for something so cheap. The belton brick reverbs are also quite amazing!

[@kirabarsmith9353]

@@DiyguitarpedalsAu Agreed, I own a Kafka reverb that uses a Belton brick, sound great.

[@erikvincent5846]

@@kirabarsmith9353 and the Belton Brick's are PT2399's as well (if you tear one open, you find 3 of them stuffed in there.

[@wesmitchem825]

Thank you very informative plus I liked how you threw in the riff from roofs got a hole from the meat puppets in there killer song don't know if you said what the max milliseconds on it was

[@erikvincent5846]

Wow! Glad someone got that riff! It's one of the first songs I learned how to play way back when. In the build doc for the Boy In Well, page 11, you will see the range of milliseconds, depending on the value of resistance to ground on pin 6. You can get up to 340ms with good resolution of signal out of a single PT2399. If you sacrifice the upper frequencies, you can make it stretch to around 633ms assuming a 50K pot plus the 2.7K inline resistor (52.7K to ground on pin 6).

[@wesmitchem825]

@@erikvincent5846 thanks yeah that was one the first full songs I learned too and the pedal goes to 340ms max with good resolution almost perfect I need about 400ms max for my normal uses so with a little tweaking and not much loss of quality sounds like a good build

[@stuartchapman5171]

@@erikvincent5846 Excellent video, I built one of your unshaven fuzz pedals recently, I make industrial dub, tape samples, oscillators etc, through a matrix mixer, delay is everything. I've built a prototype, using a couple of PT2399 prebuilt boards, swapping out the delay time ressitors, lengthy gnarly repeats. the signal goes through a second circuit with subtle settings, for a bit of shimmer, but this does have a boost button. I call it the Delverb. I generally feed the "pedal" a shot of audio, and leave it running rythmic noise, I give a little bit of feeedback from the mixer and a tiny bit of the master out, it just keep repeating, in a slow but constantly changing way.

[@CJ-rf9jm]

I do wanna build 1 of these now since I don't have a delay n already into electronics anyways. I do like that sound it delivers.

[@samueljett7807]

I'm in the middle of building one of these... my first pedal actually. Thank you for all the info that you out out here!

[@andreasdavour9973]

Really appreciated the walk-through!

[@zalhietzli]

Thanks for the very detailled explanations, that's great for a beginner like me !

[@johnsilverman2264]

Great circuit walk through - thank you so much.

[@planker]

Excellent. I feel better about the PT2399, I will give it another try. I'm watching the Video for the electronic stuff, I'm working with an AtariPunk Console as my rig, don't own a guitar. I wish. This has been a boost to return to the battle field and get some reverb.

[@yurkshirelad]

You make it sound so easy! Excellent explanation, thanks.

[@somepunkinthecomments471]

I would love for you to do the same type of video covering chorus pedals.

[@erikvincent5846]

Already got one here, kzbin.info/www/bejne/m4SxhJ-XlMtsaJo

[@somepunkinthecomments471]

@@erikvincent5846 Thank you.

[@Typical.Anomaly]

"I am the Antipop/ I'll go against the grain 'til the day I drop/ I am the Antipop/ the man you can not stop." Great information! Thank you! I currently have four PT2399's that I'm eager to play with... also some CD4024's for some major frequency-division action. I'm wondering what kind of wacky noise (literally) could be made with a pot-controlled (hehe) 555 driving an optoisolator that controls the "Time"... (replacing VR1 and in conjunction with R3 (2.7K)). Seasickness? I'm gonna find out! (Thanks for the warning about >5V on the VCC lol I usually run the other ICs ~9V but will work accordingly now lol)

[@erikvincent5846]

Playing with the oscillator for the delay can create some wonderful ambient and glitch effects. If you use a microcontroller, you can use a floating pin to do a "random number generator" and alter the PWM that way.

[@boris5448]

I really like these more indepth circuit videos!

[@stevm0123]

Great Video! Just wondering whether you can use the clock pin (#5) on PT2399 to trigger an LED to indicate the rate?

[@erikvincent5846]

Great question, but unfortunately, not directly. You would need a pre-scaler in between to make that work. So, it does create a square wave output, but it's the duty cycle that changes. So, when you have the delay time set to a 30ms slap back sound, there is a 22 MHz square wave coming out of pin 5. At a 342ms delay, it pushes out the same square wave, but at a much slower duty cycle of 2 MHz. I say "slow" as if MHz is slow, but at those speeds, the human eye definitely will not see it.

[@alanredversangel]

Love that chorus at the start.

[@erikvincent5846]

That's the DBE Lich King Chorus... and my obsession with the 80's.

[@alanredversangel]

@@erikvincent5846 Yeah I'm not a huge fan of chorus so when I like one it's a shock!

[@smellymala3103]

Wow looking thru my random ICs and I have TWO of these to play with!?

[@cuinoz3569]

Enjoyed your video. Very informative and interesting. Thanks for sharing.

[@esmaeilrezaie3890]

It was an amazing explanation ! thanks dude! I just couldnt understand what are the Pot 2 and Pot 3 are , could you tell me what is the specification of them?

[@erikvincent5846]

VR1 is a variable resistor that increases or decreases the resistance to ground on the PT2399's pin 6 (VCO). By changing the resistance, the PT2399 knows how to change its internal oscillator clock, which in turn makes the delays faster or slower. VR2 changes the resistance of the output of the PT2399 making it to the output buffer U3A. By increasing the resistance on VR2, less and less of the delay signal makes it to the output. Decreasing the resistance on VR2 allows more of the PT2399's delayed signal to make it to the output.

[@albertocagnin2108]

Thank for this video,where is possible to add a hipass filter for cut out the delay on frequency below 150 hz(the lower strings of the guitar). Please help me

[@ilioscio]

Fantastic information, thanks for sharing

[@yaminhameed1524]

Excellent video! Just wanted to ask about C21/C18 1uF used for decoupling - why is it oriented that way? I thought that it should be oriented the other way. Hope you could clear this up for me. Thanks and much appreciated

[@erikvincent5846]

They are decoupling, and as electrolytic capacitors are polar, the orientation typically matters. C18's ground will be sinking to ground via the level potentiometer (which is just a "resistor" going to ground). C21 is sinking to ground via C12 as a series capacitor.

[@redmodpedals9100]

Changing c23 to higher value would makes the delay brighter?

[@enriquecena2985]

Hi! First of all thanks for this Kind of videos so Well explained, i was wondering for example of Adding a tap tempo, IT Will be hard??

[@erikvincent5846]

At some point, I intend to cover that. It will require a microcontroller and some programming. An Arduino would be the "go to", but due to its size, I would like to go something smaller, like an Attiny, but still make it accessible to DIY'ers.

[@maxonmendel5757]

instead of tying dry signal directly from Input buffer to Output buffer, could I tie the signal from the output buffer to the other side of the RV2 level potentiometer to get a wet/dry blend?

[@erikvincent5846]

Unfortunately, I don't think that will work. Essentially, the R13 and R15 resistors are the "mixing" resistors to the summing op-amp U3A. You'd do better to replace R13 with a variable resistor (pot using only two of the legs) and that would change the ratio of "dry" and "wet" signals. The RV2 is kind of doing that already by mixing in and out, more or less, of the wet signal.

[@noisegrrrl]

Great video, I understand a lot better how it works now. I do have a question, if I wanted to make a reverse reverb type effect, would that be achievable purely using this type of circuit or would I need to go through something digital like an arduino after the delay section?

[@erikvincent5846]

Those are typically done with digital ICs like the FV-1. Not that it would be impossible with analog circuits, but I, personally, am not familiar with any.

[@maxonmendel5757]

on the pt2399 datasheet, there is a huge resistor immediately off the input that goes straight to ground. what does it do? it notice it isnt' on the schematic for the BiW.

[@erikvincent5846]

If you are referring to the 100K load resistor on the datasheet, that is an example input load. However, we are providing our load coming out of the first op-amp buffer, going into the input.

[@Sanrolino]

Well done man, excellent video! Thanks for the content.

[@glaubergarcez5182]

thanks for the video! its great that you take the time to go through the schematics. I was wondering if there is a way I could use this schematics with line level or mic? cheers

[@erikvincent5846]

I don't see why not. The only part that might need to be altered are what frequencies are being filtered. We tend you play around EQ points that are guitar or bass friendly where vocal mics may want different bands. It will still work otherwise, but how well it sounds depends on the filtering.

[@glaubergarcez5182]

​@@erikvincent5846 thats cool, I'm gonna make as it is a change if I don't like. cheers

[@ourchannel8215]

what is the name of a sound effect that rotates left and right? like a tremolo...I want to make a delay like that...can you make it like that?

[@neoxtra2461]

How do you know which caps or resistors to use to get desired effects? Is it just trial and error?

[@erikvincent5846]

Some of it can be trial and error. Sometimes it is a specific task we know what we are doing, but want to try it out, like we know a high-pass or low-pass filter, but aren't "sure" what it will sound like cutting "this" frequency over "that". Sometimes it is just reading the datasheet of an IC and seeing what passives, like resistors or capacitors do to that IC and using your imagination to go "ah, wouldn't it be cool if...". It all depends.

[@SS-mj2mq]

Great video thanks for sharing most people like detail yes knowledge is power 🤗💖💯 I have this exact same schematic in my schematic list on my Android phone. I plan on building the course pedal schematic for the PT 2399 as well. There's also a reverb pedal schematic and the echo schematic for the pt 2399 you can find them online for those of you that might be interested. 😁

[@anythingthing2311]

what is your thoughts about replacing the r13 and r15 with potentiometer and connecting it to pin 1 and 3 and the pin 2 goes into the TL072, I am thinking if you could make another control for dry/wet level

[@maxonmendel5757]

do R19 and C22 serve as a lpf for the feedback of the repeats? could you use a switch to switch that in and out ofthe circuit? like a "digital" "analog" type of switch? also, what do R20 and C23 do? i can't find them on the datasheet.

[@erikvincent5846]

That is correct, it is a lpf for the feedback repeats, at 1.7KHz. You still need "a filter" there, but you switch between two filters, one with a 1.7K knee, and one with a knee above 16K and call that the "digital" one. As of R20 and C23, that is the high-pass RC filter for the repeats. If you make the capacitor smaller, it raises the filter cutoff frequency to imitate the poor bass response of repeats in tape echo.

[@erikvincent5846]

This video may also help, kzbin.info/www/bejne/b6Srn5SLm7mKq8k

[@GeorgeGeorge-xj2bc]

I have just finished the circuit as a christmass project and it sounds amazing!Soon i will add an auxiliary input for jamming and a headphone amplifier and it will become a space rocket.The only parts i have omitted are C16 C19 two capacitors in paraller with the feedback resistors R12 R16.The level adjust if placed only in full then the larsen effect is created.Is this something normal or a lower adjustment than the full is always needed?It is a great circuit,thank you.

[@williamherbertwebber]

Thanks so much, this is an amazing and helpful tutorial.

[@jeromesurffoil7033]

Excellent explanation! I have some PT2399 chips on the way. Looks very straightforward. Thanks. Sub'd

[@thomaslioutas4417]

So, a question more like a hunch (not much knowledge about circuits, etc., just like to play around with electronics): If I put an SPST switch before r13 (after the junction that goes to pt2399), then I would have an on/off switch that could kill the dry signal, leave the wet intact and have more "ambient-like" sounds that have only delays and no dry at all? Coult it also work with a pot at the same place that will control how much of the dry signal would go into the mix (and if yes, then what value would be best)? Also, in such a circuit, where could one place a momentary footswitch that would enable the control of feedback oscillation?

[@erikvincent5846]

You would be correct in the removal of R13 from the circuit. That would pull out the dry signal. A 50K pot with pins 1 and 2 replacing R13 and pins 2 and 3 replacing R15 would be a pretty cool mod. As of feedback control, a switch that makes or breaks a resistance value to force the delay out of oscillation could be added.

[@thomaslioutas4417]

@@erikvincent5846 Yeah this chip seems easy enough to try quite a few weird mods. Was thinking even about adding a switchable octave circuit in the delay signal to be able to shape it in fuzzy, glitchy ways. Concerning the oscillation switch, my thought was going from vr3 (repeats) lug 2 back to pin 16 of the pt2399, with a trimpot or external pot (to control the amount of feedback reintroduced) and a capacitor (to filter the signal a bit). Is my thought correct?

[@erikvincent5846]

@@thomaslioutas4417 That sounds about right. Worth a breadboarding, that's for sure.

[@thomaslioutas4417]

@@erikvincent5846 Cool! Many thanks, i'll try an experimental build that I have in mind that draws elements from multiple delays and maybe post the results here in the future. Might take a few months though between work and possible fails.

[@technodruid]

How sensitive is OP2 and LPF2 pins to C10 being say 18n rather than 15?

[@lucfiumara]

Hello, I have realized that there are lots of pt2399 that are very noisy but not in the repetitions, but when given more repetition time, they emit white noise, since I have older delays that do not do so and reach very high times. superiors. Do you know something about this? Greetings and thanks

[@lithium122003]

Could you give tutorial about using DPDT On On Push Switch (6 pin) with PT2399 (Delay) ??

[@erikvincent5846]

What would be switching with the two poles?

[@lithium122003]

@@erikvincent5846 guitar delay pedal

[@martincastellano89]

more analysis like these.. yes!

[@maxonmendel5757]

what do R19 and C22 do? I haven't seen them on other delays and I'm trying to figure out what they relate to on the delay i'm working on, and if i can ignore them or if i have to circuitbend them in somehow.

[@erikvincent5846]

It's a low-pass RC filter with a 1.7KHz cut-off knee that affects the repeats, only making them darker on each pass.

[@ChuckChilla]

I built one similar to this . It works perfectly some times but some times it either oscillates or feeds back and does not get any of the guitar signal to echo. Any ideas?

[@erikvincent5846]

Without really seeing the schematic, there isn't a lot to go on. However, I know one spot that seems to latch these circuits, causing zero echo is the pin 6 VCO having a small resistance value within the first 500mS or so of "boot time". This is the reason R3 is in there. It makes it impossible for the resistance of getting too small. On some builds, this isn't present. On some builds, an RC delay filter is added so that during that first part of a second, the resistance is really high on power up, but then goes as low as you want it afterwards. On some builds, that RC delay doesn't work, and it latches up anyways.

[@Michael-lk1ox]

I don't get it.I'm headed up.I've had a distortion Pand I put the wrong size power supply and it blew up so how are you changing voltages inside?There and not blowing shit up

[@leandroconejo]

Great video, Muchas Gracias!

[@SideProjexts]

Amazing video, learnt a lot form this. Thank you!!😃

[@lvgray76]

Thanks for an informative video. Noob question: can I sub a plain LM7805 for the LP2950-50LPRE?

[@erikvincent5846]

They are both similar. The LP2950-50LPRE is a TO92 form factor while most LM7805 are TO220. They do make 7805s in TO92 footprints though.

[@lvgray76]

@@erikvincent5846 Thank you! I have some TO220 LM7805s, so I'll use that. Appreciate the quick response. Cheers!

[@DavideZanellaDrum]

Great video, very clear explanation. Thanks a lot

[@Thomas-jo8hz]

Does anyone know what software he uses to design his schematics?

[@jstro-hobbytech]

Awesome sound man

[@ekasatriabahari2264]

nice video!! hey, i build this pedal using schematic on tonepad rebote 2.5 but i can hear any delay output just clean signal i already checked pin 14 using probe and it has sound like FM tuner when i turn delay/time knob can you help me, what caused of this delay signal is not mixed up or coming out?? thank you anyway

[@EDGARDOUX1701]

Great video and love this kind of videos. Thak you for the information given, it helps me cause Im an electronic student.

[@theflyerita8794]

Thanks a lot for this video!

[@lithium122003]

I tried to build DIY Reverb Pedal with PT2399 but the problem is, the output sound just like regular guitar sound (there's no echo or reverb at all) and event i unplugged the power suplly (with batteries or 12 / 9 Volt adaptor) my guitar still can produce regular sound. I mean it doesn't give an impact if i plug or unplugged the power. Could you help me what is my mistake on my project ?? why it just producing regular guitar sound ?? why the power doesn't give any change if i plug or unplugged it ?? Fyi, i use 7805 for power and PT 2399.

[@erikvincent5846]

This could be a couple things. If your stomp switch isn't working properly, you may just be stuck in bypass mode the whole time. If that's the case, that explains why even having the power removed, it still "works" as bypassing doesn't require voltage, just a common ground. However, if switching the power on, on the pedal, and the PT2399 is dead, the op-amps will still "bypass" the dry signal, albeit slightly tone-cut. But if that was the case, when the power is removed, those op-amps would be dead, so no sound should make it to the output. So, with that being said, I'd check out the switch.

[@lithium122003]

@@erikvincent5846 i found the problem, i forget to soldering 1st pin so power from adaptor not come to the IC

[@izokzu4851]

thanks a lot man !

[@pilot140467]

I still can't understand why people still insist on using a Parallel reverse polarity protection diode, specially without a series resistor or Polyfuse. 😞 Like this, if you connect a Power supply with the wrong polarity, that diode will blow up, probably shorting itself, possibly even damaging your power supply, and if that happened at a gig, ruin your day. And I am not even mentioning the fact that you will have to open your pedal to repair it. If your problem with using a series protection diode is its voltage drop, just use a P-channel Mosfet configured as reverse voltage protection. No voltage drop at all, and it won't turn ON if the input voltage is reversed. For pedals powered by 9 to 12V, I use an AO3407A Mosfet. Connect the Mosfet Drain to input Voltage, its Source to your pedal's VCC rail, and the Mosfet Gate pin to Ground. One single component, and it saves your pedal, your power supply, and your gig. It just won't let any current pass if the power supply is reversed.

[@HazeAnderson]

Great video yes please more. 😬👍

[@freeelectron8261]

Sounds a little like the Boss DM2

[@felippecezar9117]

Shouldn’t there be a voltage rail to the first opamp?

[@felippecezar9117]

Gambero it makes sense now, it’s a dual opamp. Thanks!

[@subramaniantr2091]

Was expecting to hear Brick in the wall.

[@erikvincent5846]

Nope, but I was thinking about doing Echoes.

[@luk9465]

Nice! Is it Digital?

[@erikvincent5846]

The PT2399 is digital, but usually is coupled with a bunch of analog components to round out and tone shape the sound. Often, pure DSP delays sound bright on the delays after the primary sound, while on the PT2399, it sounds dark (highs rolled off), which analog BBD style delays typically do. This is due to the supporting analog circuits and the memory limitations of the PT2399 (it loses resolution if delay length is longer than the chip has RAM for, so we cover it up by removing the highs from the resolution, making it sound "darker")

[@luk9465]

@@erikvincent5846 thank you Erik.

[@flapjack413]

Whoa! First comment! And cool video. My first pedal build was a dual PT2399 delay!

[@HazeAnderson]

Mine too! Dual distortion + PT2399 delay that is.

[@Bishka100]

9:45 Doesn't a gain of 2 = 3db?

[@erikvincent5846]

www.sengpielaudio.com/calculator-gainloss.htm is what I typically use to calculate voltage gain to db. According to that formula, it is 6db.

[@Bishka100]

@@erikvincent5846 You right I just looked it up. I was thinking of power gain,,,, I should have done that before I posted....Sorry

[@HazeAnderson]

@@Bishka100 ++ correcting yourself :)

[@Bishka100]

@@HazeAnderson When you get things wrong as often as I do, you sort-of get good at correcting your self .

[@israelgiron9089]

cheers~!

[@alphanumeric1529]

You are a freaking HERO! Why, oh why did God condemn you to Australia? :( btw, as a post script from the middle of nowhere America, our largest county is over 1m, my particular county is half that, we didn't really do the Ko vid thing, just over 300 supposed Ko vid deaths in the year of 2020, and yeah, people over 85 years old. We have friends and family in Kalifornia, and all they talked about was ko vid and when they could get the *bloody* vakkine. Here, national chains did the mask thing, that's about it. The remaining mom and pops got a lot of business, and seem to have kept that business. I suppose they'll be targeted for pretextual shut downs, can't have people thinking for themselves, especially if they disprove the official probaganda.

[@tyayres7964]

Blue LEDs in pedals are aweful, why would anybody use these???

[@milandjordjevic7952]

Dude learn to play guitar that is torturing of human ears, explanation how delays work is equal to that playing. YT ''knowledge'' i love it.