5 Kinds of Buffers in Your Guitar Pedals

[@wilderblopes]

Best explanation of audio buffers I have seen around here. Thanks for posting it!

[@codyherring5889]

These component and circuit breakdown videos are really excellent, thank you for sharing! Orange County, California

[@pukkimi]

For me these are things that "I already know", but because I'm not tinkering with electronics all the time, these are nice reminders. Adding a spesific context (guitar pedals) may open this information for a crowd that wouldn't otherwice stumble upon it.

[@ChungasRevenge]

Excellent video! Thanks from Michigan, USA

[@subramaniantr2091]

Love your videos. You're a true inspiration. There is no one around who shares knowledge like you do.

[@blues61]

Fantastic primer on guitar pedal buffer circuits. Thanks, man!

[@brucetaylor1753]

Great explanation. Greetings from Greenville SC, USA.

[@silvertongues2]

Thanks from the UK!

[@girouxlp]

Hi from Canada! Thanks for the lesson!

[@figueroalabs]

Love the content, watching from Costa Rica.

[@OreilleGauche]

This video is as fantastic as in/out Z of the last circuit! Very good teacher! Thanks you so much!

[@TheStringDojo]

I'm the 666 like on this video! I'm reading a book for guitar pedals (Guitar Effects Explained) and this video really enhances my learning process. Thanks.

[@EDGARDOUX1701]

Love this kind of explanational videos, hope to see next stages of a pedal. Thank you!

[@bradsims7089]

I've been wondering about this. Thanks for the video.

[@miguelangelmartinezmartine8253]

Good explanation and summarize !!!

[@prsman23]

Awesome, thanks for this from Illinois.

[@ericdavey6702]

I can build a kit... but I wanna understand it! And see patterns and intentions behind the pedals. This video is exactly what I've been needing.

[@dewdop]

This is a great video, but buddy, you could just look it up at the same time...

[@ericdavey6702]

@@dewdop That's how I landed on this page. Thanks buddy.

[@DaveyGage]

Kia ora from New Zealand - and thanks for sharing your mojo in such a clear way =D

[@midwestrepairdesk]

Awesome video! Keep up the good work. Greetings from northwest Indiana

[@bobs_ya_runkle]

Many thanks from Australia.

[@pedro_rivera99]

Great explanation, didn't know about the mosfet variant and most of the cons of many of the buffers. I'd love a video about matching outdated transistors/op amps. Cheer from Mexico!

[@erikvincent5846]

We did one on transistor matching for Phasers a bit ago, but as of op-amps, we'll look into it.

[@sjay4673]

As always, great content!!

[@famitory]

would love to see an episode on the potential uses of UJTs for pedals. i haven't seen a design that uses them before and i only recently learned about them from a scan of a 50s Build Your Own Oscilloscope book

[@erikvincent5846]

Unijunction Transistors are fun. I know the Earthquaker Devices Hummingbird uses a 2N6027 for its LFO section, which in turn is a clone of the Vox Repeat Percussion, also using UJTs.

[@fiver-hoo]

really enjoying all your contributions Erik, doing some rework on a vintage bass amp I dumpster dove and was just sitting around pondering the first input stage when this video popped up, so perfect timing! Going to give your Lich King a whirl as well whenever the PCB makes it across the pond to me here in Ohio.

[@vAlkemistv]

thanks! you guys are great. from tampa, fl

[@TheFarout69]

There is a fairly simple N chanel JFET/PNP BJT combo circuit that has great qualities. High Z of the Jfet, and low Z of the BJT, better gain qualities and power supply noise rejection. but it's technically a "unity gain amplifier." I found the circuit in a Faichild's datasheet application notes for JFETS. The BJT is biased directly by the drain of the fet and they share a source/collector resistor to ground. I used an MPF-102 (now J-113) and a 5087 for mine. Sounds perfect and drives a cable real good. 2 transistors, 4 resistors and a couple caps.

[@erikvincent5846]

At the end of the day, that's an answer for a lot of big name pedal companies. JFETs in the front/in, BJT in the back/out. But, if noise floor is the name of the game, a lot can be said about op-amps in the front and back (Klon).

[@TheFarout69]

@@erikvincent5846 I believe the Klon circuit actually uses rail voltages as well, which negates the need for a bias voltage. Bias voltages can add to the noise floor. I am a fet fan though. Cool little critters.

[@lucasweisman8778]

Really appreciate these videos, thank you!

[@andyreevesarchive528]

Great vid! Thanks, Sir. Well presented, good pacing, balanced assessments. Strong work! Oh, and I build in Minnesota. Entirely self-taught, which has its pros and cons....

[@kbongos]

Hi, from MN. Thanks for your helpful info. I haven't been into pedals much, but they can be fun. I've got a Digitech do everything digital one that is alright. I got into this analog area of interest via piezo pickup pre-amps, like a simple JFET buffer. Lately I have been working on adding a basic trem, with the idea of embedding it into the guitar. I have a breadboard circuit, roughly based on this schaller trem circuit, optimized for light battery usage, so your 9V would last or you could use maybe a few smaller CR 3v batteries. Circuit uses about 200uA. A few piezo preamps I tested use 1 to 2ma typical. I've stuck with transistors for this, op-amps tend to use 1-2ma current. I've recently become aware of specialty pico power op-amps, but I haven't determined if they could be appropriate for say a piezo buffer or embedded effects. Cheers!

[@leeds99]

very informative - THANKS!. I have an op/amp buffer at the front of my board - it has TL072 - is there a difference between TL071 and TL072?

[@iblesbosuok]

No, no audible difference for most of us. TL071 is single in a package while TL072 are double in a package. If you like to do a little bit adventure, you can substitute TL072 with LF353 or LF412.

[@tubeDude48]

Mouser has plenty of 2N5457. Northern CA

[@erikvincent5846]

Yeah, after I posted this, I saw them back in stock. I remember last year, they were a pain to get. Now with this whole chip shortage issue, I am wondering if we will return to this or not on components.

[@alanredversangel]

That BS170 circuit looks a lot like the Super Hard On. Personally I use a TL072 with two buffer circuits in it at 18v. And then run one early in the chain and the other before the amp.

[@erikvincent5846]

The SHO is a common source amplifier as opposed to a buffer, but there are a lot of similarities

[@erifkind]

San Francisco here. I’ve had great success with Jfet buffers. Based on this video, I’m going to try op amp circuits next.

[@CalebePriester]

Awesome! Thanks! Can you talk about tone controls?

[@erikvincent5846]

Will have some more in later videos. We did do the tone-stack on the Big Muff Pi a bit ago, and on the LTSpice videos as well. When we get to our Meat Grinder Fuzz, we'll be looking at a Bridged T tone control.

[@papaohaokip8109]

Excellent explanation ❣️

[@off711]

Watching in CA, USA

[@jeroen4734]

Good stuff dude! I think i like using almost all of them.. depending on what im building. As an input buffer i like using a single op-amp, but it doesnt go with every circuit. Greetz from the Netherlands

[@sharaynishi]

Lithuania. thanks for the thorough explanations

[@davidfoster5906]

I am looking for a simple boost buffer circuit for tube amps with line level input.I plan on purchasing your buffer board and parts. Can that be modified for3-6db boost.Also looking for a circuit that will split 12vdc50mA to run a small op amp rumble filter of a DC wall adapter.Do you have a reverb circuit like Flying Saucer with parts and pc board.I heard one advertised, but they had a questioner to fill out.Questions like Who made the firstE-335 guitar.I failed it so thy didn't want to sell me the board! Also i plan on building a fuzz Face.Whats the difference with the transistor pair you sell.Do you have NPN BC108C silicon pairs? Thanx

[@DavidMsg]

Greetings from Singapore! I have so many questions! :) Any difference between an input and output buffer circuit? Any good examples of using a single dual opamp (eg tl072) for an input and output buffer? If the opamp buffer is seemingly the best, why are different buffer types used for different pedals? How does a Cornish buffer differ from the NPN you showed?

[@erikvincent5846]

Well, for commercial examples, the Klon uses op-amps on the in and out side. A lot of Boss pedals (DS-1, CE-2) use BJTs on the in and out, as well as the Tube Screamer, and discrete fuzz pedals like the Big Muff. A good combo I see a lot is JFETs on the in side, and BJTs on the out bound side, but in those cases, a lot are surface mount, and in that market, JFETs are more plentiful. I like using op-amps as buffers for mixers, like when you want to blend a dry signal with a wet one, a buffer is required, and I typically go with an op-amp there. Also, for gyrators, buffers are required for that, and again, I prefer op-amps in that situation. As of the Cornish buffer, it's a bjt buffer, but there is a lot of tone shaping prior and after the circuit. I am not sure that "buffer" is the word I would use, but that is what they call it.

[@ChungasRevenge]

For the buffer based on 2N3904, how was the 510K bias resistor R4 selected / calculated? Why not 560K? Why not 470K? If I substituted for 2N5088, does R4 need to be adjusted?

[@plateoshrimp9685]

The bias network needs to be chosen so that it can supply enough current to keep the bias voltage constant when the transistor is drawing it's maximum current. Basically, it needs to allow a current flow into the base that is greater than the current flow through the emitter resistor in parallel with the load divided by the transistor beta.

[@ShlomirBareket]

I noticed you have a volatge inverter, are you blokes going to offer a voltage doubler that makes a 9v - 18v with more headroom?

[@erikvincent5846]

I don't see why not. We have it configured as a reverse power setup, but not as a boost power setup. I'll see what we can do about that. On the Turbo Driver, this is built in, but I think that's about it.

[@ShlomirBareket]

@@erikvincent5846 yesh I saw that mentioned on another video. A doubler would be a great addon and it save me having to buy one from the UK!!

[@BucketofGuts646]

If you were to install an onboard buffer into a guitar what type would you use?

[@erikvincent5846]

Well, maybe none, but if you are a fan of active pickups, that is kind of the idea they play. The EMG81 is using an op-amp as a differential amplifier, but as a bonus, creates a good amount of impedance as well, using said op amp.

[@BucketofGuts646]

@@erikvincent5846 I'm trying to isolate the cable Capacitance and use an OBEL While not being stuck with a set of active pickups like EMG

[@leonardacciold]

I'm sorry man, I have a question. What is the efficiency of the power converter you are using? Is it a standard configuration used in these kind of application? If we would use a DC-DC power converter in a closed loop, the efficiency will increase at the prize of chip area and system complexity. Do you think the use of a DC-DC of converter could be beneficial? Is there a prcise reason why to use this simple converter? Thank you for your time.

[@erikvincent5846]

That's a pretty good question. Most of the DC-DC converters I've ran into are typically switchers, like the ones from Murata or Recom. They are nice, but they also have their draw-backs. Mainly, the issue of noise injection, which can effect the noise floor if not properly filtered. The Murata ones are nice, as in their datasheets, they actually put in circuit suggestions to get FCC approval, which is strict on noise rejection. Recom... not so much. I've made some circuits for driving a guitar pedal through USB with a 5V to 9V boost switcher, and though it "functioned" it just made too much noise, which in turn propagated to the rest of my pedals. Basically, if you get involved with switchers, be prepared to learn a lot about filtering. Efficiency isn't much of the issue, so much as its the line level noise.

[@leonardacciold]

@@erikvincent5846 Yeah, thank you man. I really needed an answer based on practical tests. As you correctly pointed you need to take care during the design phase of the gain and phase margins of the loop of the DC-DC and try to minimize the output noise of the system. I can imagine that with a little pole/zero analysis you can figure out a way to correctly filter out the noise, but the filter design might be tedious and of impact on the final foot print. Thanks for your help dude!

[@erikvincent5846]

@@leonardacciold Wait till you see my boost circuit I am working on to drive a tube 12AX7 preamp. I made a switcher circuit that, aside from a SOIC-8 IC, is through-hole, boosts the voltage from 9V up to 50V, but keeps the keeps the noise floor low. The only question is "is it safe" for the DIY community. I mean, I use it, but I am not the safest person to be around when it comes to electronics. I may give Electro-Boom a run for his money on electrocution.

[@veikkomultivitamiini4858]

You are in cahoots with the FBI and CIA to destroy my mojo >:(

[@trhosking]

What is causing that humming every time you speak?

[@burresseffects]

Where’s the Aussie guy?