Yes, I can 👍. It'll probably be on making any non-true-bypass pedal, true bypass. In the mean time you might find my previous video on switching useful: kzfaq.info/get/bejne/nsqlbJyT0KvJZok.html

Thanks m8! Planning on making some more vids in this style.

Reluctant to publish my email here due to bots and scammers but you can drop my a message on Insta, it's linked under the video description.

Looper pedal - yes, excellent for testing stuff hands free. I do like making gadgets though :). The breadboard pedals are invaluable when testing stuff in the chain, here's the video on one of my builds: kzfaq.info/get/bejne/msiCgsuo3pabcmg.htmlsi=6JGhQLb0jtXo7Q8X

It's not going to affect the output impedance very much either way because of the other resistors, especially RC. Therefore, my advice would be to try both values and see what responds best in that situation. Audio taper probably gives a better response but the taper is not electronically important, just how we hear the result.

@@MusicTechknowledgy thanks very much for the advice. I will give it a go!

Only ever as a rough approximation. I edited out for time but the two other meters showed 380 and 372, I believe that's because they use a different set of test parameters. The Common Emitter isn't dependent on hFE (only RC and RE values) so we're all good circuit-wise. I sometimes use a curve tracer if I really want to know specific parameters but remember that heat also affects the hFE. In comparison, all of my KT3102EMs measure a lot higher - from 450 minimum to well over 600 in two cases (their datasheet suggests a range of 400 to 1000), and I checked that on all 2 meters. They're the ones with the triangle and the letters E and P on the front. The green Russian has ones with green (KT3102) and white (E) dots and the black/yellow EHX/Sovtek version has the white triangle with EN2 (the N2 means February 2001 I believe).

@@MusicTechknowledgy Thanks so much! I'll build my pedal as is and follow along with the rest of your series!

Thanks. I was just looking at the transistors in the Green and Black/Yellow versions I have. The green Russian has transistors with green (KT3102) and white (E) dots and the black/yellow EHX/Sovtek version has transistors with a white triangle with EN2 (the N2 means February 2001 I believe). My green version should be very similar to my black/yellow version but sound-wise they are slightly different, be interesting to analyse why during this series.

Hi John, yes you can. On the output, after the capacitor. Log(A) has the best audio response but linear(B) will work well here too. The value with roughly set the output impedance . My Improved circuit used a 470ohm resistor in series with a 10K linear potentiometer to set the output impedance. See here: kzfaq.info/get/bejne/npOYeNaf3tutc4k.html&si=DDpBmRknXA2Uys-j

@@MusicTechknowledgy thanks for the fast reply. Very helpful as always. John

Me too! What's your favourite version?

Rams head is wonderful, but I'm on the hunt for Gilmours big muff triangle V2 sound! Watching these vids helps me understand more about what to look for in my own pedal design, your content is much appreciated!​@@MusicTechknowledgy

@@MusicTechknowledgy Too hard to choose!!!

Perfect timing! I just bought an unknown pedal kit on impulse and it appears to be a BMP Russian clone, with rare KT3102 transistors.

Perfect timing! I just bought an unknown pedal kit on impulse and it appears to be a BMP Russian clone, with rare KT3102 transistors.

I actually had that one already and don't know where it came from but I can definitely find a suitable replacement. Bear with me, I'll need to check the pin spacing (so it fits in the PCB) and come back to you with a product link.

I can’t seem to find the exact one, I’m guessing being Soviet made has a slightly different spec. Closest I could find and should fit (based on measurement with the callipers) is a TruConnect one with 6.3mm pin spacing and 16.2mm between the pin rows. www.rapidonline.com/truconnect-3-pole-pcb-standard-jack-skt-20-1395

@@MusicTechknowledgy Thank You so much for taking the time to look into this. I highly appreciate it! I will try to order your recommended part. I will follow up and let you know how it goes! Thank you!! 😊

Great question. It's because old solder almost always has a higher melting point, adding a bit of new solder lowers this melting point making desoldering easier. It's important, as too much heat can lift the PCB traces, especially on older style boards like this one.

Excellent stuff. Thanks :) ... It also increased my own understanding of the circuit too. I'm planning on making one on the transistor-based EHX BMP soon, it'll be several parts , but the output stage is basically the same as the LPB-1 and the other three stages are similar.

@@MusicTechknowledgy I will be tuned in! I have decided to cut my teeth on this circuit and the rest of EHX's 1969 offerings - high boost, low boost and Muff.

Hi John, 12V is well within spec. of a 5088, so the bias would change slightly but it will absolutely still work.

@@MusicTechknowledgy thanks very much for the quick reply. Much appreciated. John

Thanks. The 10uF at the end is another AC coupling capacitor, it lets the AC signal through but blocks DC from getting onto the output. The other 10uF forms a high pass filter with the 100k resistor, filtering very low frequencies to the ground (roughly everything below ~16Hz) and letting any high frequencies through. The idea is to remove any low frequencies that might overload the OpAmp or cause hum or instability.

Thanks and all excellent points. I shall continue to experiment. I feel an improved slinky reverb video might be coming in the future 👍

Excellent question. 0.6 to 0.7 volts is needed to turn on the silicon PN junction in the transistor. Just like a silicon diode. I just chose to use 0.6 volts in this example. Also worth knowing that Germanium is lower at around 0.3 volts.

Ok, thanks for letting me know. I have built a couple of these boost circuits from pcbs and recommended components. But I wanted to use different resistors to reduce the voltage gain.

@@johnr7303 Decreasing the value of RC will decrease the amplification, increasing RE will result in less gain. Try 1k as RE for a gain of roughly x10 Also note that in some common emitter circuits RE is (AC) bypassed using a capacitor in parallel with RE, and doing that massively increases gain, as the emitter is then effectively grounded for AC signals.

@@MusicTechknowledgy thanks for the heads up on this. John

Excellent idea 👍

Indeed. I might return to this and play around with some different drivers to twist this, in the future. I've seen various builders use the inner coil of a speaker (cone removed) or a small motor in their versions.

Ah, cool, that's an excellent way of approaching it, much more similar to the coil based spring driver in commercial reverb tanks. I'll check that out. Thank you 👍.

Yep, that and my playing 😂. My aim wasn’t sound quality here, as you can tell. A piezo probably won’t drive a much heavier spring, the slinky is really lightweight, but always worth experimenting. Blend control is a superb idea 👍

@@MusicTechknowledgy I don't think there's anything wrong with your playing

Sounds like a great amp project 👍. What kind of amp are you building?

👍 DIY EMT plate. Awesome.

Thank you, and yes in the future. Bucket Brigade Analogue chorus is definitely advanced audio electronics (CE2, etc) and most ambient reverbs are digital nowadays FV-1 chip. However there’s some really cool things you can do with a basic PT2399 delay chip including chorus and reverb which I will definitely cover in detail in future episodes.

@MusicTechknowledgy very interesting, I appreciate the explanation. Looking forward to future videos!

What makes some values “not preferred”? I may have missed something

Hi Allan, Firstly, that feeling is completely normal. I very often feel that way too, especially researching these videos and trying to get my knowledge to a point where it's good enough to try and show others. It does get easier though. A few years ago I didn't fully understand all the technical stuff myself, but I still built loads of pedals by copying designs I found on the internet and that actually helped loads. My advice is just to stick at it, the passion for making pedals is the key thing and the science clicks eventually. Plus, I'll be making some more videos aimed at beginners soon too 👍.

@@AllanHathaway Great question. Resistors come in "preferred" values based on a series of values called the "E Series". The E24 series is most common these days. So in that part when I calculate 400 ohms for the Emitter Resistor but pick a 390 ohm resistor, it's because 400 ohm is not in the E24 series but 390 ohms is (and 430 ohms is also an E24 vlaue, but 390 is closer to 400).

Probably. I mean the square was bit is fairly easy with clipping. It’s the time it takes to charge discharge the capacitors being a function of frequency that’s going to be tough. Got me thinking now 👍

You're very welcome 👍

Excellent question. The Cin Capacitor (10n) blocks DC (and low frequencies) so there's effectively no DC voltage division by the 2M2 resistors.

@@MusicTechknowledgyaha! ok thanks!

Excellent stuff on the summing amp, happy to have helped 👍