Tone Stack Bypass Mod | Tube Amp Mods | Fazio Electric

[@PetraKann]

I like this sort of modification. With a simple switch you can keep the original circuitry of the Amp as well as being able to cut Out some sound colouration and produce a “rawer” sound.

[@hyperluminalreality1]

A 100k Linear pot in place of the switch is way more useful. From 0 to 5 it acts as a mid control with more range than a Fender mid control. Above 5 it gradually lifts the ground to act as a tone stack bypass. That way you can have the most responsive mid control ever AND a tone control defeat.

[@daleburrell6273]

​@@hyperluminalreality1...how do YOU know that?!!

[@soloman4547]

Super cool and a major tone change just at the flip of a switch. Nice!

[@timmooney7528]

Nice video. It's a simple mod, but the difference in the sound is huge.

[@kjneese]

Wow! When you flipped that switch...TWEEDY GOODNESS! Great video!

[@carnage77]

A switch with a selection of resistors in this position ❤

[@markhammer643]

I did this mod to a blackface Tremolux head I had some 35 years ago, after reading about it in an issue of POLYPHONY magazine. I enlisted one of the unused jacks for footswitching it in and out (although that requires use of well-shielded cable). There is no *specific* change to resistance recommended, just more than what the stock resistor value or midrange pot is. So if it's an amp with a 6k8 fixed resistor, adding 12k on top of that will do nicely. There is no doubt that the resulting change in signal amplitude hits later stages harder, but modest resistance increments achieve a somewhat hotter signal with a less scooped tone, suitable for solos. There's also nothing that says one couldn't insert a 50k pot in series with that ground resistor or midrange knob to set whatever level of boost one wants. Interestingly, I was tinkering with the circuit of a Boss BD-2 Blues Driver the other day, and realized that it employed a circuit just like a Fender tonestack between its two discrete op-amp stages, with a 15k "bleed" resistor, analogous to a standard Midrange control. I installed a 3-way toggle to produce alternate bleed resistances of 40k and 100k, and achieved enhanced "drive" identical to what this amp mod does.

[@tradermonk9403]

Big difference! Sounds like a good mod for Telecast players.

[@stevebeck3164]

Colleen, the signal is still passing through the treble and bass caps/pots between tube stages. It's not "completely bypassing the tone circuit" with this mod. It's simply removing the ground reference, allowing more signal to pass to the next stage, which you can hear overdrives it. It's definitely interesting, easy and minimally invasive.

[@chipsterb4946]

Replacing that 6.8k resistor with a Mid pot (25k or 50k) gives you so much more versatility. Also, it is good practice to leave a big resistor (1 meg) in place and have the switch add or remove the 6.8k resistor. Sometimes completely lifting a ground connection has bad consequences.

[@stevebeck3164]

@chipsterb4946 I agree. Mesa circuits are usually designed that way, with a switchable 33k resistor in series with a 10k (33k gets shunted to ground when deactivated), along with a treble shift of .001mf cap in parallel with the 250pf cap using a DPDT Push-Pull pot/switch. Yields a great Texas blues/Dumble OD sound.

[@jasonsansome5579]

​@@chipsterb4946To be honest, you don't really notice much more gain with the end of the circuit lifted above ground by more than around 100k, so you may as well solder in something like a 82k-100k resistor. If the extra gain causes the amp to squeal, a small cap (around 500-1000pf) in parallel with the new resistor should stabilise it.

[@jjsant3250]

I've done this on my '71 SFDR and '74 SFVC. More noticeable at high volume. Restores the mids that are intentionally scooped in the stock setup. Used push-pull volume pots to switch. Push is boost and pull is stock.

[@amast3rMind69]

I did it years ago to my silverface champ. Killer tone

[@jlore6344]

WOW! I did not think I was going to like this mod, as I like the tone stack in a Fender (like the blackface sound more than the tweed). HOWEVER, that sounds amazing! I love that switch and now want a Princeton dang it!!! Thanks for sharing these types of things, this was great. I also love watching, and listening, to you solder and connect things too, so please keep doing that. Thanks again.

[@huffy5505]

Did this mod to my Princeton Reverb and my Musicmaster amps a few years ago. Love it!

[@thatampguy]

It's a great mod. I like making it footswitchable by using the reverb's RCA jack to do the grounding.

[@daleburrell6273]

...I wouldn't go THAT far...(!)

[@techslfink9722]

Love this kind of non-invasive mod! And the sound is great too!

[@stevencochrane115]

Another great mod for tweeds is a triode/pentode switch, awesome sound, I've installed this and the tonestack by-pass on my tweed deluxe. Briiliant mod!

[@KarlKarsnark]

I love how doggie and the bass have the same paint job. Cheers!

[@mikefromusa6902]

I just put together a PR kit myself. You got me thinking. Sounds tweedy… there’s even a dummy ground switch in the back of the amp I can repurpose! Thanks Colleen

[@banjomandan7199]

Thank you! Can't wait to try it on my '79 Vibro Champ!

[@mikestarmer3121]

I really enjoy your videos, you’ve made me realize I can repair my own amplifiers

[@vayabroder729]

Nice; sounds like a useful mod. Gives the tone some hair; a little bit like a Tubescreamer.

[@gigmandrew8975]

Fabulous! The bypassed tone was great.

[@fiddlix]

Coleen, another way in the circuit to do a similar but different sounding to your mod is to parallel a .001uf with the 250pf treble cap in the stock circuit. You can put this on a switch too. Experiment if you like. A fun rabbit hole to jump down no doubt. Great video as always. Cheers..!

[@renegade44040]

I heard the difference. I guess I can describe it as two different size pipes with water flowing through. You bypass the tone stack it was like a bigger pipe for water to flow through.

[@FazioElectric]

That’s a great way of visualizing it! I love the water flow analogy when thinking about current and such

[@billedwards2657]

Best mod. Great video. Single channel ab763 with raw mod is my favorite amp all time.

[@dontuckerjr]

Great idea. Thank you. It seems this gives the player direct control of the amp tone by using tone and volume on your instrument. 👍

[@MrPnew1]

Nice simple and as you say, non invasive mod. Thanks a lot Colleen 🙏

[@progresspedals]

Love this mod too.

[@TheLamboman640]

Nice. I love these videos! Lets see a NFB mod done!

[@sundance222]

Interesting. Though I am not as familiar with Fenders. Cool, I would imagine pushing the volume will really have it break up nicely

[@Avi8torDavy]

Great video! I had heard about this mod, but didn't realize how simple it was!!!

[@patthegunsmith]

I'm building a Deluxe Reverb kit and this mod is going in. Another mod going in is a 5K pot in series with the 820 Ohm NFB resistor.

[@williambock1821]

Foot switch is nice with this mod.

[@rockrenegade]

It definitely produces a more “raw” sound as has been described to me. I’d love to hear a ts bypass on a gainy Marshall type amp. It looks absolutely insane on the value calculator graph.

[@juniormint3136]

Colleen, great vid as always. Can you do one of the bassman ten combos? A vid on beefing up that channel one, its anemic. Maybe talk about how it's a james tone stack, give some unique insights.

[@chrisaungier2394]

Great video, something I've been thinking about and you demonstrated how to accomplish it. So I'm replacing the volume pot on my Champ with a push pull pot to defeat the tone stack. Thanks

[@Krunch2020]

Wow! Amazing difference!

[@ericedelman]

I'm going to try this on the "normal" channel of my 1978 Twin Reverb. I never use that side, so it would be cool to have a use for it. I'm thinking I could wire it right to the "bright" switch.

[@crankshaft383]

Awesome. Thank you. 110 comments in 1 day. 👍 I've always liked amps with this option, and thought every amp should have this switch. Wonder if it can be done on most/all amps. I have a 1980-ish twin reverb ultra linear.

[@spunkmire2664]

Such a fantastic channel, good on ya!

[@nate433]

Oooh would love to see more mod videos!

[@Kobe-lh9wp]

Nice video! I see people on tik tok with custom grill cloths and side panel vinyl. Could you make a vid about changing those pieces on the amp. Keep up the good work tho!

[@DogatHeart]

Slick mod.. really clever and sounds unlimited ! Great Thanks 🌏

[@U2WB]

I love your videos; they are so fascinating and enjoyable. This time I have a question about the mic ! What kind of mic are you speaking into ? It sounds so warm and clear - fantastic sound !

[@thelategreatnocoastsaint]

Be right back, I now have some silver panel tone stacks to lift.

[@johnp75]

That's a great mod. Thanks

[@TheAaron3dg]

Very cool! Great explanation

[@ListentoKadence]

This was a fun video. If you thought about shooting another amp mod video, I would love to learn how to install a bright switch on my 65 Champ Amp with a JBL D216.

[@ericwilson2585]

Interesting wondering if I should do that to my revamped Bogen now.

[@lordgraga]

Super cool!! So basically in this style of TMB circuit, if there was a mid pot, then what it would do would basically to lift the entire circuit from ground as you turn it up? Would this make bass and treble less effective? And finally, would a pot (say 1K A/J) make sense for this instead of a switch, for that reason?

[@clownhands]

Every fender amp should have a Neil Young switch

[@hyperluminalreality1]

Why not put a 100k pot in that position instead of a switch? Use it as a mid pot. 0 to 5 is a wide response mid control and above 5 it gradually bypasses the tone stack. Same TMB delete but with a very usable mid control.

[@fuzzmountain7583]

That is my favorite version of this mod as well.

[@FazioElectric]

There are so many great versions of this mod! I love how versatile the concept is. I showed the SPST switch just cuz that’s what my client had wanted for his Vibrochamp :)

[@fuzzmountain7583]

@@FazioElectric Silverface Fenders are top shelf mod platforms across the board. Really enjoy your channel, cheers!

[@mantashaft]

My Bronco amp just tapped me on the shoulder. I've never heard that particular mod before. I was thinking it might be quite nice with a fuzz pedal...

[@FazioElectric]

A Bronco is a great candidate for that mod!

[@Psi105]

Try a large knife or chisel tip on your soldering iron. You will find soldering way nicer. Conical tips are awful and small conical tips even more, but people usually don't realize until they try something else. It's sad how so many irons come with a conical tip as standard. I prefer knife tips because it gives you more options in how you use it.

[@lemon__snicker5973]

More heat transfer with a larger surface area, sure, but it boils down to user preference and temperature setting.

[@goodun2974]

Chisel tip is always my preferred choice, lthough that's not a good way to describe it because the so-called "chisel" has a blunt, rounded-off end. This probably confuses people who are new to soldering and the associated equipment.

[@DayInTheLifeOfAl]

Great video. Any chance you’d look into how I could increase my reverb on a Mark V 35? Thank you.

[@ZombieLincoln666]

By passing the tone stack in my DIY tube amp (ax84 p1 extreme) helps so much. It’s pretty low wattage and passive tone stacks suck too much gain.

[@danielbarbieri8199]

Great hack I own a black face princeton reverb I made a few years ago. I guess it will worth a try...😉

[@jefffree6990]

Nice - it sounds great Could you explain how to make it minimally invasive, without drilling any holes? I dont think anyone wants a toggle switch floating around inside their chassis

[@FazioElectric]

Right! As I explained, I left the switch out for the sake of the demo. When I performed this mod for a client, I installed a switch in the second input jack position. I believe I mentioned this too ;)

[@andrewksadventures]

That sounds great! It would be cool if that was footswitchable! I wish you were my amp tech, but Australia is a long way away! 😉

[@mikewithers299]

Awesome stuff right there Colleen. You are a wealth of knowledge on vintage amps ❤️❤️

[@ManMartin]

Hi. You can do the same mod but using the existing low input jack. I mean the ground is there, you disconnect the 68k and the signal and route the resistor to the signal positive of the jack. Then you use an external pedal to boost the tone stack connected to this low input jack. Remember that with no male jack inserted the jack joins ground to + signal internaly (the mids resistor now). Thanks

[@ManMartin]

I hope you get my poor explaination.

[@tbonky]

That mod has a nice growl!

[@jasoncartwright586]

Really interesting - thanks!

[@srinip]

Same as the Dumble "pre-amp boost", right? It would be even cooler to make it foot-switchable, and I imagine that's pretty easy to do. It's also what some builders like Greis and Allen do - I've owned both, and it's an awesome mod.

[@colinsmart4316]

Have a Fender hot rod and Mesa Boogie Rocket 44 of which love the clean channel on both amps but the dirty channels, not so. Presently waiting for a 12AT7 tube to slot into V3 on Hot Rod as heard that it will help out and create a better tone? . Would love to see some experimental mods on both of these amps to hopefully make them more appealing to my ears on the gain channels.

[@TK-fk4po]

Sounds great and so easy! How hot do you run your soldering iron?

[@joeltunnah]

I hate guitar amp passive tone controls, so being able to bypass them is a good thing.

[@RulgertGhostalker]

it would be lifting the ground on my mid pot , in my case ( marshal topology ); but my tone stack mod is so hot, that the tone stack cranked, ( with a little pull down on the treble ), is almost the same thing.

[@elliotstout5732]

Could you attach this mod to a twins bright switch ? I want to do this to my 1970 twin and the bright switch on it doesn’t work so I was wondering if could repurpose it for this mod ?

[@mikehembree7973]

1. Neat 2. Can it be done stealthy with a push pull pot? 3. Can it be done on the reissues?

[@BasicDrumming]

Great video.

[@MarcCarriage121]

That was awesome. Thank you.

[@MikeJordanAA763]

Hi Colleen, is this a mod that can be easily done on most Fender amps? For example, a blackface Concert Amp or a 2020 Princeton?

[@BorjaTG]

Nice mod! Which input would you leave? Because this amp have Hi and Lo impendance. Cheers!

[@daleburrell6273]

2:26...there's WOOFER!!! I'm a Kitty person, myself...

[@eatmarth]

This mod reminds me of a Treble bleed circuit inside a guitar.

[@hyperluminalreality1]

Not even the same principal. Putting a cap and resistor across a volume pot is way different than lifting the ground reference of a tone stack thus giving it a raw unequalized amp tone. Completely different operation and result.

[@vincentgates5596]

whoa! Cool. So much more gain….When you lifted the tone stack the amp went straight into overdrive. Why is that?

[@oldguy5381]

Cool mod, like it 👍

[@paultraynorbsc627]

Thanks for sharing 🎸🎶🎸🎵🇬🇧

[@seanblythe9109]

Very cool stuff

[@klepetar]

maybe i'll try this.. thanks for the tip ..

[@eduardoreyes221]

Hi! thanks for the video i will do it on my amp. Its possible to use only the power section in a fender twin?? Thanks a lot

[@yoshiyaz5882]

👍😃

[@mikefromusa6902]

Yup. It works. 👍

[@cliffbungalow9373]

Any tweaks for a 5E3 kit?

[@miekgenklefin9616]

What was the amp volume level set at ?

[@bluedot6933]

can you do a video on removing the reverb rca jack? can't seem to find out how.

[@borowland5744]

Have you ever serviced one of those Groove Tube Soul O amps?

[@that_thing_I_do]

I love the smell of soldering in the morning....

[@mikewithers299]

🤣🤣🤣

[@hyperluminalreality1]

I love the smell of Multicore 362 flux in the wee hours...smell like.....victory!

[@thermionic1234567]

I’ve got a lot of soldering to do and you’ve rekindled my love of the smell of resin!

[@thermionic1234567]

Alomar? As in Carlos?

[@chuckmaddison2924]

I miss it since I got a tremor in my hand, which resulted in more solder on my face.

[@NoSeAsuste]

Have you tried in a Marshall JTM?

[@alioth2021]

Would it be possible to use a footswitch with this mod? Kind of like a channel switcher.

[@dennismullins4930]

I’d like your opinion of the new Gibson amps design. ☮️

[@hyperluminalreality1]

Why do you need her to tell you that the Falcon 20 is a max $750 amp. That the sideways PCB mounted preamp tubes closed behind a screwed on back panel is a disaster of a design. That they are in no way a "hand wired" amp. Colleen is a nice person. Don't make her say negative things.

[@dennismullins4930]

@@hyperluminalreality1 just trying to help the algorithm with a like and a comment. You are very negative. You need to work on that.

[@HardwareScience]

I refresh and this video shows up ❤❤

[@rkgaustin]

Can this be made into a foot switch also?

[@jjiacobucci]

That mod does sound better

[@zombiemontage]

I have one of these! Nice

[@zdenkokovac2896]

Ej najbolje direktno bez filtere👋💫💫🙏❤️‍🩹

[@davidbailey6350]

I have a Ampeg amp sitting in my garage that was my brother in laws, he passed away and it’s something I know absolutely nothing about it.

[@chrisguy7833]

be cool to just add a tone knob in the bypass circuit.

[@you166mhz]

ever worked on a Carvin amp ? ....

[@agharta42]

could you do this on a 15w Pro Junior?