One knob boost circuits, EP, LPB, DOD 250

[JustinFun]

I've built a ton of one knob boosts as my main amp (a 70s HiWatt) really likes them for a kick from crunch to distortion. My absolute favourite (which doesn't seem to get much love elsewhere) is the Seymour Duncan Pickup Booster. It just seems to give a really natural and dynamic boost. I couldn't comment on how much of that is to do with the interatction between the pedal and the specific amp though.

http://tagboardeffects.blogspot.com/2012/12/seymour-duncan-pickup-booster.html

[Killthepopular]

I've breadboarded the LPB successfully. It has a badass, fat, fuzzy tone when you hit it with a hot signal and gives a thin but clear clean tone when you roll off your guitar volume. It was a bit easier to make it than I expected so I might have a go at some more of the simpler circuits mentioned in this thread, namely the SHO, the stratoblaster and the AMZ mosfet.

On a largely unrelated note, what's the reason why guitars seem to start humming slightly when you roll back the volume? Both my guitars do this. Is it a common phenomena or just something crappy in my setup?

[m_charles]

I guess I should be working from schematics, not layouts?

God yes. Don't get stuck in the paint by numbers perf/vero/breadboard rut.
Learning to read simple schems is much easier than it seems and will make life so much easier in the long run. Its also very satisfying to build from a schem. It feels more real if that makes sense.

[Killthepopular]

It just occurred to me that I have always loved what my DS1 does to the feel of my guitar, even when it's set totally clean, so I thought I'd add the DS1 output buffer to my list of circuits to try out. Here's something i cobbled together from the electrosmash page, from the power and the output schematic:



Would this work as a standalone buffer?
Does the circuit make sense? I took R24 and R25 from the power supply bit. It looks like a generic 4.5v divider.
Do i need to get a 2sc2240 or can I just use another transistor? I have these already: J201, 2n5088, bs170, 2n5457.

[Mark Hammer]

I've built Fred Briggs' "64 Vintage Vox" circuit, and quite like the tone.  It includes gain and limiting controls, but those can easily be internal trimmers, rather than panel-mount pots, keeping only the volume control once you find a tone you like.
http://revolutiondeux.blogspot.com/2012/02/fred-briggs-64-vintage-vox-tones-galore.html

[bluebunny]

Would this work as a standalone buffer?

You'll have DC at the input, which probably isn't what you want.  Lose R19.  Out of your list of transistors-to-hand, only one is a BJT.  The good news is (as R.G. will tell you) that you can almost always use a 2N5088 where you see an NPN BJT.

[Killthepopular]

Lose R19.  Out of your list of transistors-to-hand, only one is a BJT.  The good news is (as R.G. will tell you) that you can almost always use a 2N5088 where you see an NPN BJT.

Like this?



Does it matter if i don't use those exact caps? Are they literally just there as RC filters? I have 15n and 0.1uf. 1M+15n=11hz. 100k+0.1uf=16hz.

...Actually I do have a 47n after all, but I don't have a 1uf.

[Killthepopular]

I've tried the LPB1, Echoplex, AMZ mosfet, SHO and now I'm trying the stratoblaster. I've encountered a weird issue with the stratoblaster circuit. I'm recording identical clips of each circuit so that I can compare them all later. I'm using my ROG condor for some of the clips, but annoyingly the stratoblaster doesn't want to work with my Condor. The stratoblaster works fine with my amp or with my Joyo california sound pedal. It works fine going straight into the soundcard. The condor on its own works fine. But as soon as I go Stratoblaster -> Condor the sound i get is that weird, incorrectly biased, voltage sag type sound. Very quiet, very gated, then you hit the strings and a raucous, farty distortion leaps out at you. Then it dies away and goes quiet. It sounds like the way my condor sounded when I hadn't set the trim pot correctly. I've tried different batteries on the stratoblaster and different power supplies for the Condor and get the same results. Somehow the stratoblaster seems to make my condor incorrectly biased. That's what it seems like... Anyone know what's happening here?
Incidentally my condor uses a 2n5457, as does the stratoblaster. The ep3 circuit used a 2n5457 too and worked fine.

[garcho]

I highly recommend something like this:

http://www.madbeanpedals.com/projects/_folders/1590A/schematics/Bloviator.gif

Acts as a buffer as well as a "nice it up" filter. The BBE/Aphex rack units were a fad for a while, people made outrageous claims, and they were abused by radio stations and jingle houses, so they have a bit of a bad reputation no. But I think that comes from people imagining their use tracking or mixing in a modern recording studio, where indeed, unless they make that "magic" sound that's exactly what you were looking for, they're not very useful, and/or harmful, and/or a PITA for whomever does the mastering. BUT, with a guitar in front of a tube amp (some SS are ok too, some fight it), something like the Sonic Stump project can bring out a much fuller sounding steel string tone, especially if you're playing clean.

Also giving the AMZ mosfet booster a vote, I've gigged with that thing for years. A simple textbook circuit like that often does everything you need without any crappy sound baggage from over-engineering.

[Killthepopular]

I highly recommend something like this:

http://www.madbeanpedals.com/projects/_folders/1590A/schematics/Bloviator.gif

Also giving the AMZ mosfet booster a vote.

The bloviator is a lot more complex than the other circuits I'm trying. I'm building 6 different circuits, all of which only use 1 transistor and 8-12 other components. I've already built the AMZ mosfet.

I'll give up on the stratoblaster. Sounded good to me but just doesnt seem to want to work with my cab sim.

Here they all are:













I've done 5, just got the DS1 buffer left to try.

Anyone got any more ultra simple boost/buffer circuits of this ilk to recommend before I call it a day?

To reiterate, I'm just looking for a fairly transparent circuit that can manage unity gain but doesn't have to go much beyond that. So far I've found that, to my ears, 5/5 circuits that I've tried have made my guitar sound "better" somehow. Better impedance matching maybe? I don't know which I will build ultimately but If i had any 1 of them I would be inclined to use it as an always on pedal. That's how much of an improvement these circuits all seem to make to my guitar/amp sound.

[Elijah-Baley]

I see all transistor based circuits. What about a simple op-amp booster? Something more simple than a MXR Micro Amp or MXR/CAE MC-401 Boost.
You can adjust the input impedence acting on a pair of resistors, and adjust the volume/gain acting on the gain resistor in the feedback. And of course a pot to use as master volume pot. I found a sort of it really transparent and with none distortion.

[duck_arse]

I'll give up on the stratoblaster. Sounded good to me but just doesnt seem to want to work with my cab sim.

not until we say.

we can't see the circuit of your condor, but the one I looked at had no DC blocking cap at the input. and I see from your stratoblaster circuit [which also has no input blocking cap ....] that the output cap is a tantalum. if, perchance, you happened to fit that particular cap backwards, it might leak enough to re/mis bias the following input, if it didn't have an input blocking cap.

measure the voltage at the output of the stratoblaster. is it 0V00?

actually, a second glance at the straoblaster shows it doesn't have ANY gate bias. you need a resistor from gate to ground, 1M, 1M5, 2M2, 3M3 ..... doesn't matter exactly. circuit won't work reliably without that resistor.

[bool]

Stratoblaster was designed to get the gate "bias" from guit. vol. pot. Actually the internal resistance of any passive pickup would bias the fet. It looks just like a textbook fet amp adapted (simplified) for guitar. I had a similar ckt in one of my basses in late 80's. Well, it didn't last long in there...

[Killthepopular]

the output cap is a tantalum. if, perchance, you happened to fit that particular cap backwards, it might leak enough to re/mis bias the following input, if it didn't have an input blocking cap.

In the words of the great Hans Landa, "that's a bingo". I had already dismantled the stratoblaster circuit and moved onto the next circuit when you posted this message but i thought I ought to go back and re-build it seeing as you took the time to have a look at it.

When i built the stratoblaster circuit the first time, I got to the 1.5uf cap and looked and the symbol and thought "right, well I know from working with diodes that a straight line means the negative leg" and completed the circuit accordingly. When I re-built it just now I actually bothered to look up the circuit symbol for capacitors and found out that the straight line actually means + not -. It now works with my condor.

I'll add the stratoblaster to my other recordings and do some double blind listening tests (to see which circuit most appeals to my ears without a biased opinion) and report my findings.

[Gus]

Try a search for "booster buffer"  in this forums advanced search
select match any words
You will find threads
Also look for the LPB, ecoplex etc. threads that have been posted over the years
A lot to read but it should be worth it.

Something I need to make time to build and test. The parts to the left of the input are a simple guitar sim with one single coil pickup
https://www.diystompboxes.com/smfforum/index.php?topic=99139.msg868712#msg868712

[duck_arse]

the tantalum markings have caught many a builder, many a time. do you have any non-working builds with them in?

a "straight line" on a tant should be accompanied by a row of "+" symbols (unless yer using surface mount parts).

[Killthepopular]

the tantalum markings have caught many a builder, many a time. do you have any non-working builds with them in?

Sorry, I should have been clearer. I was referring to the straight line on the schematic. Not the cap itself. The cap itself had a longer leg and two plusses on one side so it was obvious which way the cap was polarised, I just didn't correctly understand what the straight line/curved line symbol on the schematic meant. I thought a straight line on a schematic indicated the negative end, as with a diode.

I've only built one pedal so far, (the condor) and that didn't have any tantalum caps. I built that one from a layout, not a schematic so i could see which way caps should be oriented from the layout, I wasn't confused by schematic symbols.

[duck_arse]

ahhh, so, was the 10uF C1 a tant as well? and backwards, was it? the clue is in the ground symbol on one end of C1. the other end must be more positive than ground, and that implies the orientation of C2 as well.

[garcho]

I see all transistor based circuits. What about a simple op-amp booster?

+1

Have you tried a simple non-inverting op amp buffer as an always-on device? Could get away with no pots if you wanted. That was part of the obnoxious Klon hype that has thankfully passed, for the most part. Or you could try an inverting op amp with gain in the feedback loop, you can have less-than-unity gain, if you want (obviously as much positive gain as the op amp/ps permits), still ultra simple.

[PRR]

> which way the cap was polarised, I just didn't correctly understand what the straight line/curved line symbol on the schematic meant. I thought a straight line on a schematic indicated the negative end, as with a diode.

The original electrolytic capacitor was a round jar with a flat plate inside. The flat plate was "+". The symbol became a curved line for the "-" electrode. I can't even find a picture of that construction now, but that's the back-story.

There are a dozen other "standard" symbols. Google "electrolytic capacitor symbol" when in doubt.