ECE4448 L40: Treble Boosters -- or Bass Tamers? (Guitar Amplification and Effects, Georgia Tech) 

I can’t afford going to school so I’m very glad I found this channel. Thank you.

Should I have been 16 again and lived in the USA this video series would seriously push me towards EE at Georgia Tech. Keep up your good work Mr. Lanterman, greetings from a Polish sparkie 🙂

Love this channel so much. Your ECE4450 lectures helped me out massively with learning to design synth circuits. Really been enjoying the guitar amp/fx stuff lately as well. Thank you so much for putting this info out there man

The way guitar technology just took a chainsaw to terminology is hilarious🤣 Plus, the whole "tremolo arm" and "vibrato" on old fender stuff lol

This channel is a total gem!!!!

damn this channel is making me wish i went to georgia tech, i'm an EE student at U waterloo right now and god damn do i wish i had you as a prof

I need to check out full courses, I tinker but audio isn't something I have done but I have been working on original effects so finding this channel is like finding gold

Interesting properties of the germanium ones, the leakage current between collector and base creates negative bias feedback which when then circuit is biased at the optimal place creates compression (distortion) that is pleasing to the ear and feels nice. There is also high capacitance between the base and collector and base and emitter which rolls off extreme highs so it becomes more of a bandpass type of circuit that's non-linear in terms of filter design. It's a fun circuit like the fuzz face where making minor changes can really affect the sound more than you'd think it would. -Edit- Oh and the large bypass cap on the emitter resistor can also take a bit to charge up and stabilize and creates compression too. The early morley power boost with 50uf bypass caps also exhibits this behavior.

Instead of using a separate power supply, you can just use a polarity reversing adapter on your standard center negative jack to make it center positive for PNP pedals.

I have read that Vox amplis in the beginning sound was considered muffled, so guitarists started using treble boosters to balance the sound. One was Ritchie Blackmore in the beginning of his career. Before he started using Marshalls.

In this case, the ac base resistance is a few k < 22k. (beta x 30 Ohm)

1:02 got me good. Excellent video as always.

Woah insane prices! Back in the late 80s and early 90s I studied EE and was a musician and on Saturday’s I would fix amps and setup guitars in my friend’s music shop. The Ibanez tube screamer and BOSS distortion were expensive! And I said: “I can build the electronics literally for around 5 bucks. The most expensive part is the case really. And you can actually mesh them together with a hard clipping (saw the schematic in the opening), soft clipping and have a separate one channel EQ that can come out in a different output, that allows you to pan it and/or mix it for recording. A nice low end chug on a dedicated channel is cool (that was before the 00s metal 😂). And my friend was like. I will make the cases! You design the circuit and tell me what you need. I created 100 boards in school - the manual drilling was the worst, these days I would just JLCPCB or PCBWay it 😂 And he router a nice buck. We made a nice 2 part mould and cast it in polyurethane resin (which later budget pedals were done in ABS plastic). And we had a little workshop. We made a 100 all numbered and we sold them for 200 guilders a piece. The Ibanez tube screamer cost that much and the BOSS over drive and heavy metal drive cost 150 I believe, a bit loer ik price than ours. And basically we had them all in a nice little box. With more tonal variant because we could select the type of clipping diodes and the number 1 or 2 per side. And we sold out in less than 3 months. And there was a demand for more. But it’s just too labor intensive to make them. We easily spend an hour per pedal. And then 200 bucks for 2 people in a shop, isn’t a lot!

I'm instantly intrigued by your channel I'm going to need to study up to understand the formulas but I comprehend it somewhat

You know Duane Allman was known to use the Vox Distortion Box with the Tele he was using at the time, back when he and Gregg were in Hourglass. Pretty sure he's using it on 'BB King Medley' from the Duane Allman Anthology 1. Being a Duane Allman addict, I got my middle name Duane, from him, I've tried to find a schematic for it so I can build one but no luck so far but I haven't really looked at all. I want to see how it sounds with my Tele with "Fender American Vintage 52 Tele" pickups in it. All the gear I have is based on what Duane used lol. Tele. Multiple LP-style guitars. A 335-style. Some. Strats. My gold top with a Seymour Duncan Seth Lover neck and 59 bridge pickup is #1. Love that guitar and it was only $250. I've put at least twice that much in parts in & on the thing lol. It's an incredible guitar. The neck angle is flat, like an early Les Paul where my P90 gold top has a neck with quite an angle to make room for the P90s, I assume.

Thank you very very much for the insight into this unit, I’m an iommi fan. Ive always wondered.

Why PNP over NPN for a treble booster or other vintage guitar pedals ? When i studied electronics my instructor explained the difference , basically NPN has less internal capacitance and has a brighter top end , PNP has high frequency losses compared , you could use a shunt cap across the collector and emitter to simulate a PNP with an NPN ! a small value but with a noticeable effect. So since its treble boosting pedal that slight high cut helps balance it , same with the fuzz face NPN vs PNP the NPN would have a touch more highs ! I found building a treble booster i created some mods to get it better performing with my amps , i like adding a switch to remove the emitter cap C3 ! That helps flatten the freq/gain high end for a more neutral boost , to get more gain out of it also i removed R2 , creating a current rather than voltage biasing ! you will have to set R1 to a higher value depending on the BJt's particular gain ! Which also increases the input resistance and sensitivity . other things you can mod is C1 higher/lower values , since R2 is removed it would need tweaking to keep the original response, i always use switches for these mods except the bias which is fixed once achieved.! No bother tracking down an old NOS PNP BJT ? unless you want to get closer to the original Gain is the important one , but keep in mind Germaniun PNP BJT's had poor quality control , leakage and poor gain tolerances. Its still treble boosting with C3 switched out of rather some low cut going on determined by the input cap value ! i especially like the pick attack it creates ! gives an amp that vintage overdrive attack, my modded TB will get some asymmetrical or class A type harmonic distortion , it will overdrive a Fender Twin channel very nicely at a clean setting of the amp just by over driving that input stage !

Nice humming in the audio, Prof. Lanterman.

The Dallas Rangemaster is actually a Hype-Ass High Pass filter. The scratchy pot makes it 'vintage' sounding, probably. Dallas should have gooped their circuit to maintain the mystery.

1:02 HONK!

These treble boosters were originally a way to make many UK made amps of the early to mid 1960s to have a more treble like focused sound of the blackface Fender amps. How well they achieved that goal is debatable.

It's like why a Picasso painting costs millions of bucks, it's just 50 bucks worth of paint and a canvas, it's a collector's item. And, the Treble Booster was boosting more mids to high-mids to distort an amp, so to eliminate the bass "flubbiness" of a full stack, and that lack of bass made the name. It's like the Tube Screamer is ideal for boosting an amp into distortion because it rolls off bass (below 120 hz, I think) and boosts mids and doesn't have the problems of treble boosters (unstable germanium transistors, reverse polarity power, lack of tone control).

It's important not to neglect the interaction between the guitar pickup and the input capacitor, and the resulting ~ 800Hz bandpass filter that is created there. The Guitar's volume pot affects the Q of the filter, at low settings it creates additional brightness, but as the volume pot is turned all the way up, the direct coupling produces a pronounced 2nd order bandpass filter. *This* is the real beauty of this "simple" circuit...

I recreated Dallas RangeMaster with germanium OC44 and installed it in a guitar with a built in 9V battery . It works fine….😊

I truly enjoyed the analysis, thank you! We all agree these items are nonsensically overpriced, however collectibles never were rational. However, there's a bit of a mix between electronic concepts and musical concepts in your video. In the field of electronics, we agree that an output signal being different other than in amplitude from the input signal would generally be considered distorted. In the field of music, where psychoacustics rule over engineering concepts (although engineering can and should definitely be applied), this isn't necessarily so: a signal that's heard as mostly «unbroken» would be called saturated, while a «broken» signal would be called distorted. This is where overdrive and distortion pedals are different: the former traditionally would provide a signal only perceived as saturated that would later overdrive the different stages of an amp, even at the power amp, so it would distort; the latter would already provide a distorted signal, the amp wouldn't really need to distort by itself, ideally the power amp wouldn't distort anything, just amplify. Both approaches to distortion sound noticeably different, and feel very different to the player, hence each would be favoured for different styles. I believe this is a good explanation here from mostly an audio or psychoacoustic perspective: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-qQPYMfcPzY0.html This can be seen in the time domain, and I'm missing that in your video, since you only analysed the frequency domain of these devices. The Dallas Rangemaster, a favourite of many 70s blues rock/hard rock players, not only cuts bass in the frequency domain, but it also provides saturation in the time domain, so it would cause amps to distort even at the power stage. It would also provide an asymmetric clipping to half of the wave, this being part of the «magic» mentioned by players, since it's musically more appealing than symmetric clipping across the wave. There's a thorough analysis here, both from the electronic and musical perspective: www.electrosmash.com/dallas-rangemaster Nowadays we definitely have better circuits and I wouldn't look forward to go back to the old tech. Heck, I even use solid state amps. But there's some «mojo» in the old tech, because those design flaws sound attractive, more interesting that perfect signals. Good thing that nowadays we can analyse and replicate them in a much better way.

C1 = 1uF and C2 = 100uF gets close to a flat response for guitar. Double those values would be even better. Modelled with a 2N3904 - a mid 60s silicon NPN. A British equivalent of the era BC108 performs similarly. I didn't bother searching for Germanium models.

I agree with you that "magical" electronics don't exist. I make my own pedals, and I would feel guilty putting super high prices on them.

These circuits actually do distort a bit when hit with higher output pickups.

An overdrive pedal with 4 times as many components costs about 1/3 what some of these companies are charging for a Treble Booster circuit. It's crazy!

Four thousand dollars! For something that costs maybe 5$ in components and perhaps 20$ for the enclosure!

Any advantages of using PNP transistors compared to using NPN transistors? Because that is weird when using PNP transistors it leaves the DC voltage on the pots wiper instead of using an output blocking capacitor.

Is the Vox Treble Booster what they used on the Vox amps? That extra switch in the back?

Personally if I wanted to call it a “treble boost” I’d make an amplifier circuit such that the low frequency gain is always 1, and the high frequency gain and corner can be altered independently. With an op-amp. Also not sure how I’d go about trying to include the emitter resistor into the corner frequency calculation. Intuition tells me that any current going into the base will go through that base resistor and just act like another parallel resistor to ground of that value, but then I try to think about the current coming through the emitter, and the 0.3V drop, and I lose any confidence in that intuition. Think I’ll stick to op-amps.

Wouldn't changing the capacitors in the guitar it's self achieve the same low pass filter effect?

No to the rand(all) comics. Other than that, I love your lectures. Even this guitar stuff is interesting, though I'm currently building Eurorack modules.

I would soooo love to donate but im poor ha :/ still loving the videos !

This is exactly why I built my own Fuzz Face. 8 parts on a breadboard that costs $15 versus $125 for the pedal. I made my own for $15 lol. Using a BC108C transistor in Q1 with a HFE of 800 lol. Q2 is a 2555a or whatever that common silicon transistor is. After that, I built an EHX LPB1 booster to put in the FX loop as a double master volume lol. I started to build a Rangemaster but the LPB1 is what I ended up building. It was the first pedal i build strictly from the schematic. The Fuzz Face was copied from Smallbear, where they show you step by step how to build the FF on a breadboard with pics of everything as they install it.

Is he going to talk about Fetzer Valves? 🍿

i got 5288Hz am i in the ballpark?

The reason why these simple Bass/Treble booster pedals are so expensive is not because of the parts in them, it's the fame and the name you're paying for, and those who sell these vintage pedals are just getting greedier and greedier as the years go by, I built myself a Rangemaster Treble Booster and it probably cost me something like Au$50.00 or so in parts.

I don't understand anything because there is no Turkish language option in the subtitles :(

I'll be controversial here and say that the so-called "mojo" of vintage electronic parts doesn't actually exist, the reason why those parts were used to make these vintage fx pedals were used, wasn't because of any magical "mojo" qualities supposedly inherent in them, it was simply because those parts were all that was available at the time, quite often a lot of those old vintage parts were un-reliable and prone to failure often without warning, but some unscrupulous people try to make money off them by making a big song and dance about the "mojo" qualities of the parts.

I love when people who know destroy idiotic myths used to rob people of their money.

So, they designed a passiver RC filter with a subsequent single transistor amplifier. The brilliance is not in the engineering, but the commercialization. An engineer probably couldn't bring him/herself to do such a blatant money-grab by abusing people's ignorance.

Well I am not sure of what pay grade you address, but when you mention an IC ....you are not mentioning the internal architecture on the chip and how many components are put on the chip when comparing it to a simple Transistor 3 legger. An IC 3 leg is not what it appears as it appears on the paper for a schematic......and not talking about the doping factor on setting up a piece of silicon to do ANYTHING before moving to the Next Level.. But yes its a simple Line Booster with side effects per the silicon. Vacuum Tube is a DISTANCE of electron travel compared to Silicon PNP/NPN function as a simulation to the grand daddy of Vacuum Tubes in electronics......

LOL, that Beavis Rangemaster is really a POS. It's not even going to produce a consistently bad sound, what it does will vary depending on the output impedance of each guitar and the input impedance of each amp.

Big Cursor Alert 4:02

Price is just a marketing ploy . Like most overpriced things . 😊

“Misguided” 😂😂😂😂😂😂😂😂😂😂😂😂😂😂 its all SNAKE OIL!

At the end of the day, people who buy this shit thinks they have good toan but really they're still just playing 0-3-5

Don't ever forget that 99.9% of guitarists are insecure enough to spend ANYTHING on some box that they don't understand as long as someone with KUDOS said they used it.

Misguided 😂 most commonly desease under guitar playing dentists 😂