Revealed : The Secret Tube Amp Power Reduction | Attenuator MOD

[@WaylonMcPhersonGuitar]

🎸I've wanted to get this mod out for a while, have a blast installing this in your own amp!!

[@fredhamilton1701]

I did something similar to a tube amp around 1986. IIRC, the bottom of the phase inverter is ideally a constant current source (though you can get close enough to it with a resistor which is what is traditionally done). Well I replaced it with a proper constant current source, with a pot that allows you to vary the (constant once it is set) current. It was a textbook solid-state current source, probably 2 transistor, but since all it did was provide a constant current, it didn’t add any “transistor” coloration to the sound. I think I labeled the knob “Squelch”. The funny anecdote is that I had just graduated as an electrical engineer when I came up with this, and my dad knew the new marketing guy for PRS guitars. PRS was considering making a line of amplifiers, so I got an interview with PRS himself. At this point I should say that while I love electronics, I was terrible at physical things. So the amp looked like total shit. The knobs all had different length shafts, the labels were handwritten on torn-off pieces of masking tape. I didn’t care about that at all - PRS’s craftsman would do an infinitely better job than I ever could. All I cared about was the sound. So I went in to see Paul, and his eyes bugged out at how hideous it was. I said sure, that’s where your guys come in and design something much better. But I don’t think he could get past it. He did plug a guitar in and play through it (unsurprisingly he was a great player), and then he started getting interested, particularly with controlling the distortion with the constant current source. But he ultimately said something along the lines of “No thanks, but I really liked that “Squelch” knob”. So I didn’t get the job as a 22-year-old Amp Designer for PRS, but I did learn an important lesson about how much presentation matters, even when it technically shouldn’t matter. After that, everything I exposed to the public/my management/etc. had a much more attractive appearance, and it led to a successful career. So thanks for the lesson, Paul!

[@scottyvalero3691]

Thanks for the story! Very fascinating.

[@erikr968]

This is an old and well known method. Maven Peal amplifiers called it a "Wattage Control". Kevin O'Connor writes about it in his book "The Ultimate Tone 4. 3rd Power Aplification uses a version of if which syncs the change of phase inverter bias with a conventional master volume called the "HybridMASTER".

[@larrysteinke1839]

if it sounds good do it, but I think you'll find that this mod doesn't actually get you distortion in the phase inverter but just reduces its gain by essentially increasing the negative feed back of the differential pair. In that case it's much the same as a normal master volume. A post phase inverter master volume on the other hand is almost as simple (a dual pot and 2 coupling caps) but allows true overdrive of the phase inverter stage. Other mods that can work great but are more complex are ones that scale or regulate the high voltage supplies, like London Power power scaling or simple mosfet regulators like the Dana Hall VVR.

[@WaylonMcPhersonGuitar]

Thanks for checking it out! From my experience installing this mod in well over 100 amps, it definitely get dirtier, you'll have to give it a try :)

[@Dix-j8b]

Also, (unless I'm missing something here) the effect of the presence control on a Marshall (or any other amp so equipped) would be altered as well.

[@deanallen927]

THANK YOU! For not referring to the phase inverter as a preamp stage. Amp "reviewers" do that every day and it's so annoying.

[@erikr968]

The tone in the tests is almost clean and the master volume is set relatively low. It could just be preamp distortion we're hearing in all clips, in which case the conventional master volume would have had the same effect. I would like to see another set of tests where you crank the master volume on the amp to really push the phase inverter and output section into distortion while keeping the preamp gain low. Compare the effect of using the MOD, OX and the regular master volume. In addition, include clips with the volume normalized for a better comparison.

[@paulrico317]

Great video. First time I've seen it in public. I did it accidentally when I was building a plexi and installed a 47K instead of the 470. It sounded good at lower than expected volume.

[@trevorus]

I did exactly the same thing, building exactly the same amp! That's pretty crazy.

[@paulrico317]

@@trevorus I always wondered if a pot could be put there as a MV, but never tried it. I've used PPIMV's which screw up the presence circuit, Pre PI masters that only work in some amps that get their gain in the preamp, half power switches and attenuators. I've finally settled on the Fryette powerstation. It does the thing Eddie did where the amp output is reduced to line level and then reamped with a clean power amp with an effects loop in the middle.

[@vincentcuclair5522]

Can you still use an external attenuator together with this mod?

[@brianingram2068]

@@vincentcuclair5522 Yes you can, but the external attenuator will mostly lower volume but not increase distortion. The change to the long-tail's bias resistor will cause it to deliver less output signal, so the output tubes won't be driven hard enough to make them distort (the phase inverter distorts instead). So power goes down because the output tubes are receiving a smaller drive-signal. Adding the external attenuator will further reduce the amount of power delivered to the speakers.

[@PrinceWesterburg]

There was an amp 15-20 years ago that had 'variable power attenuation' but it could have been an HT mod. Certainly your idea is a really good idea as it sound pretty much the same as the OX-Box but without pushing your output valves, which is super desirable! Gods I need to build an amp now to try all these things! :D

[@mcswordfish]

I'm glad you mentioned a PPIV and I would be interested to hear a side-by-side comparison of these two methods - they are very similar in the sense that they make the final output quieter by reducing the signal hitting the power-valves, but by doing this in a different way, I would imagine they'll impact the final sound, especially at higher distortion levels. Interesting video, thanks

[@thatampguy]

Great channel🫡. I stumbled across this mod during a restoration of a silverface twin. I had no idea what was going on until I drew it out. I thought it was useful.

[@giulioluzzardi7632]

You must be Telepathic because I was looking at doing the same on a Deluxe reverb amp but I only got as far as replacing an ecc83 with and ecc81 in that phase inverter slot. All by accident cos I went into a domestic electrical appliance shop and the "Grandad" was in his workshop at the back still fixing old Radios and he gave me a spare German made ecc81( 12at7) by Telefunken to try instead of the one that was in there( old one had cracked ) and it made the amp sound louder and a bit dirtier( don't know why)..but in an effort to get a bit more gain at lower volume I began looking at mods around the no1 pre-amp( ecc83) and there are loads of resistor swapping mods but your Phase inverter +resistor and 100k pot is the answer. Thanks, saved me( and others).a lot of time fussing about and getting no-where. Keep up the sterling work.work.

[@G-Point-EU-AU]

12AT7 = ECC81 itself is a much better tube for phase inverter.

[@FatBoy7.3Powerstroke]

The Ox seems to compress the bottom end more, the attenuator mod is really impressive to me, Great Video!

[@vincentcuclair5522]

You could replace the volume pot with a stacked pot = no extra drilling and 2 ’volumes’ stacked 👍

[@G-Point-EU-AU]

In the guitar amp every tube stage adds some distortion and tone, in the simplest version, it is the input tube, drive tube, phase inverter, and output tube(s), some distortion adds an output transformer and loudspeaker/enclosure, a little bit affects adds power transformer and power supply (diodes and caps). This mod reduces distortion affects from the output tubes (less power -> less distortion), transformer (less power -> less distortion), loudspeaker (less power -> less distortion), and power transformer/supply (less power -> a little bit less compression/more dynamics). This mod is changing feedback and a little bit affecting distortion too. Noted in someone's comment: "A post-phase inverter master volume on the other hand is almost as simple (a dual pot and 2 coupling caps)" method - is not affecting feedback, but all the other are the same. The method to reduce loudness is the so-called load box, but even it reduces loudspeaker distortion (because less power is going to the loudspeaker). Another method used in studios is an isolated box for the loudspeaker enclosure, or an isolated room (both cases with microphones inside). The best room is a tiled (reflecting sound) bathroom!. Like almost everything for electric guitar amplification - the "wrongest" is the best :))). A real attenuator is only an acoustic attenuator. But all the above methods can be usable and interesting. The guitar tones are in science-based alchemy...

[@KarstenJohansson]

I did it Van Halen style with a variac, 'cos I had a very loud amp that had no gain control. This allowed me to crank up up for some distortion, but not going deaf in the process. Your method seems so much safer!

[@GRedit1000]

did you re-bias for the variac?

[@larrysteinke1839]

the problem with the variac method is that it also reduces the heater voltage which isn't good for the tubes.

[@KarstenJohansson]

@@GRedit1000 Nope. Hadn't occurred to me it might need to be. It's adjustable, so if it goes out, it would always be out.

[@GRedit1000]

@@KarstenJohansson there's a video on youtube where EVH's tech points out, that this is the step everyone misses when they do the variac thing.

[@vespass225]

@@larrysteinke1839 I have run variac for years on a daily basis, with drastical reduction of voltage, from european 230V down to 160 V. No problem what so ever with any of the tubes, which makes me think that a low heater voltage likely is not hazardous for a tube.

[@paulmarcdugre]

Back in the late 70s I used to put a variable resistor between the two outputs of the phase splitter, after the coupling capacitors and before the grid stopper of the output tube grids, worked great! when used extremely it loaded the two halves of the phase splitter and created some cool distortion,

[@terrydemol5354]

Nicely done Waylon, you're an out-of-the-box thinker. What you have implemented is a Vari-Mu (compressor topology, should be called Vari-Gm) which is pretty cool applied to a guitar amp.

[@bluzmansix]

Nice one Waylon - really simple and sounds good on your video. Just about all my amps are single ended these days so I can't really try it out, but I love the idea.

[@fsarfino]

Ox seems to retain more low end while cutting the highs at full attenuation. Where as the mod seems to retain the highs while reducing the lows at full attenuation. Thanks for the info !

[@wreckoningday]

Right after the first demo I was hoping for one of them just matched up but thought, no one does that... Thanks for doing that! I'm going to try this

[@void_snw]

Personally I still prefer the crossover + ground, aka Lar-Mar style master, as it doesn't affect the tone of the amp as much (less negative feedback is one drawback). Almost all of the "power amp distortion" we hear and love is just the phase inverter, so messing with it's bias may work well for clean tones but on an amp where you wanna push that PI I doubt it'll sound nice. Would certainly affect the tone at the very least. Cool idea though.

[@sahlomonic]

Only issue with that particular amp he did the mod on, is the Depth control becomes much less effective with a Lar-Mar style PPIMV (from what I remember reading). Otherwise yes, I like a PPIMV too.

[@void_snw]

@@sahlomonic yeah, you gotta have adjustable negative feedback to get that back. That's the only drawback I know of, too.

[@adrielrowley]

Thank you for sharing this. I am a bit tripped out, I been thinking last couple days on how to do the opposite, then KZbin recommends this video as if reading my mind. I am thinking of a step further: a bias switch for changing valves. Say 12AX7 to 12AY7 or 12AU7 to 12AT7. But, when trying the online bias calculators, they couldn't produce a loadline for the latter. Cheers, Adriel

[@M2Texas]

Hey man, I have to say that I have absolutey no idea what the hell you are talking about in this video. But I'm letting it play all the way through and commenting so you get some algorithm love. Why? Because I don't know what you're talking about and that is very, very unusual to me. I want youtube to actually show me stuff I don't know anything about. So... I'm going to spend a little time trying to understnd this but since I have no interest in tube amps (I jjust don't hear enough difference to care) I want to hear opinions that are different than my own. So, here we are. you get a comment, and a long one, so I keep getting exposed to stuff I haven't ever even thought about.

[@WaylonMcPhersonGuitar]

Awesome! Thanks man haha!

[@giulioluzzardi7632]

Don't think too much just listen.

[@norbertsmallegange6331]

Do you know what the phase inverter does in a tube poweramp?

[@chrisstevens4680]

If you are not into tube amps then there is no point in watching this video!

[@giulioluzzardi7632]

We need your kind of sincere comments on you-tube cos everyone and thier granny is an expert now. After over 40 years of working with this stuff I can't say I know everyrhing, love this channel, he is trying to help us save time/money.

[@giulioluzzardi7632]

Geof the Guitar tech from 1945 used the "Carpet" method. If it's too loud bung a carpet or rug or wool blanket over the speaker.I use the fx send/return with a GE7 as the pedal cos it has level and eq which works really well for reducing vol also if It has an ecc81(at7) phase inverter valve put an ecc83( ax7) which has lower headroom. I like this resistor mod if you have a spare amp it's a good thing. So if you have a send/return try a ge7..if you don't have a tech nearby and you are'nt good at soldering or have the shakes. Peace.

[@GRedit1000]

That seems to be a great and easy mod. I don't like attenuators because they really alter the sound with more attenuation (compression… dull sound etc - though I haven't tried the ox yet ). I think you should loudness match the recordings - you can't really compare sounds that are not at the same loudness level (louder always feels better/more exciting). Still a great video and interesting mod - will recommend this video to my tech guy.

[@GaryGraham-sx4pm]

post splitter dual 100K pot before output grid stoppers but with anticlockwise pot pins connected to negative bias in the case of fixed bias (or from -ve voltage tripler from filament ac), instead of to ground, grid bias resistors swapped for 100K of less resistance. this gives pot clockwise original output tube bias, anticlockwise; reduced gain, higher coupling impedance and higher voltage (colder) bias, preserving output headroom 'squelch' at low volume. also, there is a gremlin with increasing the length of the slitter tail; a rise in cathode voltage nearing max cathode-filament volt limit..

[@paulj0557tonehead]

Of course the Trainwreck I,II, and III Master Volume mod is also easy, inexpensive, and sounds amazing! One dual potentiometer and two capacitors. It is highly functional, easy to install, cheap, and has been used by tens of thousands!

[@jamesprice6381]

i gotta few secrets up my sleeve after 31 years modding, n bldg for Diaz, Matamp, n QuestTone, but brother thats VERY KOOL! Im positive amp cos sooner or later wil inc this :) Great job! Ive done this in other ways, that are not variable but could be made variable, but nowhere near as good as this!

[@robertdonosobuchner3129]

Great video as always! Thank you for all the information!

[@WaylonMcPhersonGuitar]

Glad you enjoyed it!

[@jojokeo]

Wondering how the sound, feel, & tone differs between 12ax7, 12at7, and 12ay7 pi tubes? (The way the resistance affects each tube type vs its normal base tone, sound, & feel) Is it more useable on a ax7 vs the ay7??? Next: How is the Presence control affected or not? (Mostly a ratio by the lower resistor on the tail)

[@giulioluzzardi7632]

A good quality AT7 should give more headroom on paper but in my Deluxe it gave it more drive in the Phase inverter slot. Only way to find out is to try it. One thing I noticed is that a good phase valve is more effective than changing V1 for a different feel and tone.

[@vespass225]

I usually put a 12au7 or 12at7 as phase inverter in both my Marshalls and Peavey Classics ( -92 50W 212 ). That gives a nice basic volume drop. Whatever is needed from there for late night rehearsal volume I take using a variac.

[@kristhompson8112]

Chur... Just discovered your channel today, and subbed, Nice finally to find another Kiwi on line who knows what a "Valve" is , and is use to working in 230v 5oHz LoL

[@tracyblair3064]

I really love this mod! I'll keep it in mind for my next tube amp.

[@serapiopereziii3741]

This video got me to subscribe! Bravo, well done!

[@SpeedfreakR1]

Hey, will this work on a solid state or valve state amp?

[@chrisgmurray3622]

Yes, I did notice the slight muting the Ox had in its supposed off setting. As for your mod, isn't it just a post phase inverter volume?

[@WaylonMcPhersonGuitar]

Yeah, I do love the OX though :) It is different to a PPIMV, I talk a little about that at near the end of the video if you want to check it out

[@nikolaprokop2228]

If the resistor is 680 ohms, what potentiometer and resistor values ​​should I use. Thank you.

[@jedishaw6771]

Will it work on a phase inverter that isn't a long tail pair? Buy the way great informative video!

[@AlanW]

This sounds perfect for my old Gibson GA 19 RVT, but ... damned if I can't find the phase inverter resistor. V4 seems to be split completely differently in this oddball amp.

[@jimgibson9811]

Merlin Blencowe (the ValveWizard) mentions this possibility in his 2009 book "Designing Tube Preamps for Guitar and Bass"

[@marcoa.moreno5821]

WOW, what a great solution, Thank You! Do you think it can be implemented in a Blues Jr?

[@WaylonMcPhersonGuitar]

Yes, this works in a Blues JR

[@simonsmith2642]

I play Valvetrain, and it doesnt have an attenuator it has whats called a “governor” and thats what this reminds me of. Now that I have it, I couldnt live without it. This looks like a governor mod.

[@Elektronijaenis]

To me even the first Ox clip with it totally "off" sounds a bit overdriven. In contrast, the mod off (where the amp is practically stock) sounds almost totally clean. The rest of the comparisons seem to do same. The ox was always a bit more overdriven. Also maybe a bit darker. For these kind of tones I'd prefer your mod. Makes me wonder what the difference would be with heavier overdrive.

[@brandonpicou8017]

How would this work on a higher gain amplifier? Would I lose gain with this mod?

[@WaylonMcPhersonGuitar]

You should get more 🤘🔥

[@wallpapermusique]

Will this work on PI's other than the long-tailed pair type??

[@WaylonMcPhersonGuitar]

No, just the LTP, cheers!

[@wallpapermusique]

@@WaylonMcPhersonGuitar tnx

[@m.vonhollen6673]

I’m going to tell you about F.R.E.D.’s (fast-recovery epitaxial diodes). They will make any amp with a solid state rectifier sound much better.

[@vincentcuclair5522]

What pot value would i need for the AC10C1 (1.2K ohm resistor)?

[@WaylonMcPhersonGuitar]

You'll have to watch the whole vid for the answer ;)

[@RozsaAmplificationLLC]

Ive been saying this for not years, but decades! It's common for people to mistakenly install a 470k in a schematic like this at R18 and wonder...why is there no output or almost no output? When you say to solder the resistor from the middle pin to the pin on the right....what you're really saying is from Pin 2 (wiper) to Pin 3 to be exact! With the put facing AWAY from you and lugs on TOP, from right to left, the pins are #3, #2, and #1 and typically, #3 would be an In, #2 our Output and #1 to ground when set up as a gain or master volume pot. Some people might now like it, some might. It's up to the person, but works! It seems like you left the master on "4" or wherever it was.....try attenuating, but then turning the Master up to compensate....maybe start with the master on "10" and attenuation to max....then back it up to where you want!

[@xband]

What do you think the equivalent attenuation is in dB? Can download an app and measure from the phone the relative difference.

[@WaylonMcPhersonGuitar]

It all depends on your amps design, cheers!

[@xband]

Sorry, was suggesting you measure it, if you have an Apple Watch try using the sound level exposure app, a yellow ear icon, gives sound levels in db. Interesting thanks!

[@raycochrane3971]

I have a PRE phase Inverter MV in my Marshall Superbass...it's pretty cool.

[@scottdunn2178]

What's your favorite output transformer core material?

[@buzzedalldrink9131]

metal so it works😂😂😂😂

[@darrenfoxwell7831]

I found the full ox was considerably lower in volume cool mod but might just be you tube.Ive got the captor X.wondering if I should have got the ox .I do enjoy the captor for recording and late night volume cranked sessions. I allways learn stuff with your videos your the real deal just sayin.Not like the other 97% of wankers on you tube.Seriously dude keep up the approach you have Its refreshing and real.👍👍👍👍👍👍👍👍👍👍

[@WaylonMcPhersonGuitar]

Thanks man :)

[@mark006868]

@darrenfoxwell7831....The meer fact that you are asinine enough to call 97% of people on youtube wankers...must make you part of those 97%...just saying...

[@b-spot]

The Egnater Rebel 20 uses this

[@fin.d7725]

Have you worked on a 5E3P “Proluxe” amp before? I have found the schematic but I don’t see the cross at the power inverter showising the proper resistor? I acquired it by accident, looking for a 5E3, and it sounds so good but the Amp is so loud I think something like this would help.

[@erikr968]

The 5e3 has a completely different type of phase inverter, so this won't work. The 5e3 is a prime candidate for a post-phase inverter master volume though (PPIMV). Google PPIMV and "Lar-Mar". It uses a double (stereo) pot, and should not be too difficult to install.

[@fin.d7725]

@@erikr968 Thank you very much!

[@puzzlefactorysoundstudios]

Good idea. I would probably have wired the pot backwards so that clockwise becomes louder (less attenuation).

[@WaylonMcPhersonGuitar]

Yes, you can do that, you just need a reverse audio taper pot :)

[@cdngtrplyr]

Is there a similar mod for an SE amp ?

[@WaylonMcPhersonGuitar]

I have not experimented yet with SE or other Phase Inverter types, I'll have to look into it, cheers!

[@larrysteinke1839]

SE amps don't have a phase inverter

[@pettesisterna]

How different is this from the "volume pot" on fxloop?

[@jojokeo]

It’s only a Vol control to the signal before hitting the inverter. The mod changes the inverter’s operation / characteristics

[@erikr968]

Volume pot in the FX loop is exactly the same as using a conventional master volume. It reduces volume before the phase inverter and power tubes. This method is only useful as an emergency way to get the volume down. It won't retain any of the characteristics of something like a Plexi or other non-master volume amp.

[@opt123123]

The brand Mojave Amps have this circuit in them, have been sold since around 2010 i think

[@Damaral63]

This looks similar to the Limit control in a 1980s Mesa SOB.

[@AsyncVoid]

Amazing, I wonder if this is the mod in the Rockerverb MKIII. I can give it a trace and get back to you if you're interested

[@WaylonMcPhersonGuitar]

I've installed it on one of those, it works great :)

[@AsyncVoid]

@@WaylonMcPhersonGuitar The Rockerverb MKIII already has an attenuator, I was wondering if its the same mod as yours

[@WaylonMcPhersonGuitar]

@@AsyncVoid Oh yeah, the MKIII does, it would be good to find out, thanks!

[@frankdiaz5877]

nice mod thanks

[@WaylonMcPhersonGuitar]

Glad you liked it!

[@totallyunmemorable]

I'm not clear on the difference between your mod and a post-phase inverter master. Neither affect power tube distortion, correct? You're just getting preamp and phase inverter distortion in both cases, or am I wrong about that?

[@glasaudio]

The 470ohm cathode resistor that he's adding the 100k pot onto in series is essentially changing the bias of the phase inverter. That cathode resistor quite literally is the bias resistor for the long tail pair. Since the resistor is unbypassed, the gain stage experiences cathode degeneration which increases headroom and a nicer compression/distortion. As we increase the cathode resistance with this pot, the cathode degeneration is increased further. Ohms law proves this - as the current through the tube increases, it also does through the cathode/bias resistor which means the voltage across that resistor also increases. Furthermore, with an increased cathode resistor, the bias is shifted colder and colder. This is desirable for a long tail pair because the colder it is biased, it decreases the gain which will prevent the non-inverting output driven power tube from red plating. Now, a post phase inverter master volume pot will simply turn down the volume without doing any of the magic sauce I mentioned above. Also, this LTP bias mod is much easier to implement with less/cheaper parts. The only downside to this 'mod' is that there is in fact DC present on the pot which will create a scratchy sound when it's adjusted - and, as shown in the video, it isn't an immediate change. A small price to pay for a usable feature.

[@erikr968]

Yes. Both the "MOD" and a post-phase inverter master volume reduce the signal going to the power tubes. The MOD reduces gain and headroom of the phase inverter. The idea is that it keeps the amount of clipping reasonably the same at different output levels. It works, to some degree. Both solutions have their pros and cons.

[@Crabfather]

First !! Man you have the best content !

[@WaylonMcPhersonGuitar]

Thanks a lot!

[@dazzlenconfused]

i have a 5e3 i would like to do this for is that possible? because the cathode is 1.5k

[@erikr968]

No. It only works on amps with a long-tail phase inverter. The 5e3 has a different phase inverter (concertina).

[@rb032682]

cool stuff, thanks

[@drmaawenz]

Carlsbro did that back in the 70ies.

[@chrismitlyng1411]

Interesting to hear…. The Ox does color the sound for sure. Loses some texture compared to the mod to my ears.

[@tman6495]

The simplest "mod": A volume pedal through the Effects Loop

[@willdenham]

Ox's are $1,000 U.S. Are you saying they are triple over there?

[@WaylonMcPhersonGuitar]

Yep, $3299 NZD here :(

[@bungalowbill3409]

Should've just used a stacked pot for the volume and made your mod the center pole...

[@fahey5719]

Interesting.

[@tomcoryell]

I thought your mod sounds better than the OX. The OX seemed to thin out the tone to me.

[@lucyfuir6386]

Isnt it Kool and the gang

[@WaylonMcPhersonGuitar]

Yep, Got Auto Corrected :)

[@lucyfuir6386]

@WaylonMcPhersonGuitar lol nice. Thought I was crazy for a second

[@sirduckoufthenorth]

How about a reampbox

[@aaronzimpel4995]

ah ha! this must be how morgan amps does it.

[@Hellseeker1]

I'd say just buy an attenuator instead of risking destroying your equipment.

[@pedrolourenco2707]

Orange is using this on the bedroom/headroom switch on some amps and its sounds bad. Sorry :/

[@WaylonMcPhersonGuitar]

Interesting, thanks for the info, I have a schematic but It looks like Orange implements this differently, so it will sound way different, where did you get your schematic?

[@pedrolourenco2707]

@@WaylonMcPhersonGuitar I have an original schematics for the rocker 15/brent hinds terror, but they also do it on the OR30! They use a fixed value resistor... Dont get me wrong, if you start clipping the PI it might sound cool, but for moderate attenuation it sounds a bit harsh to me!

[@willhoren9200]

Chube emp.

[@WaylonMcPhersonGuitar]

See everyone!! That sweet New Zealand accent is taking over 🤣

[@therewasascene]

:D I appreciate you putting “long tail pair” on the screen.

[@myuncle2]

@@therewasascene is it pear, peer, pir, per, or pair?

[@therewasascene]

@@myuncle2 Yes. :)

[@fredericnoel5794]

it is not a good method de down bias the amp, the tube will work cold.. yes power attenuator on output are using tubes, like when you play full power but you can get the real sound of the amp biased correctly

[@erikr968]

This doesn't affect the bias of the power tubes, only the phase inverter preamp tube. Cold biasing of preamp tube is no issue, in fact it is often used for tonal purposes by Soldano, Mesa Boogie, Marshal, et al.

[@fredericnoel5794]

@@erikr968 exact i miss understood, then it is a master volume to crontrol what is sent to the grids of power tubes

[@luckystiff9360]

I don't know about everybody else who uses attenuators on a regular basis, but I use them so that I can get power tube distortion at a reasonable volume! This mod defeats that purpose.

[@WaylonMcPhersonGuitar]

Thanks for checking it out, maybe have another look through the vid, you'll find that is not the case :)

[@alex4k]

Sorry, not so secret, it´s a well known mod.

[@edsavage6214]

Why couldn't you just underbias the power tubes?

[@MikeGervasi]

It's spelled "Kool" not Cool.

[@WaylonMcPhersonGuitar]

Dang, stupid FCPX auto corrected it!! Thanks for the spot!

[@papajtheterraplanebluesban4224]

Why would you demonstrate this mod using a clean setting? Who cares about attenuating an amp using clean settings? We use attenuation because we want to drive the amp into non-linear operation and have it break up while maintaining a tolerable volume level, i.e. we want it to distort without being too loud. Please demo your mod with the amp cranked up to where it is distorting.

[@damianstrochnetter9735]

Jit Setty? Long tailed pier? Scimetic? Random use of vowels??

[@damianstrochnetter9735]

Tist?

[@chrisreich40]

Yeeaaahhh - Dude, that's not a proper attenuator as it's intended to be used. All you've done is to add an alternate volume control. That's all the other so-called "attenuator mods" do. To get the effect of an attenuator properly, the only way to do it is to wire a proper attenuator between the amp output and the speaker. Everything else is something else. That includes this.

[@davebolden4355]

Thats a master volume not an attenuator. You can simply add a ppimv by blending the two output signals. They are out of phase and cancel each other out. The method used in the video has nothing to do with the power tube distortion you can quiet with an attenuator.

[@SkyValleySpaceCadet]

dumb mod mate. your preamp volume pot does the exact same thing

[@WaylonMcPhersonGuitar]

🤣🤣 Classic!

[@estring69]

Obviously not an attenuator before even watching the video.

[@WaylonMcPhersonGuitar]

How so sir.. Please explain :)

[@estring69]

@@WaylonMcPhersonGuitar An attenuator in the normal context accepts the audio signal from power tubes that are being driven for effect and attenuates that signal. Significant power attenuation involved. You want the tubes driven to do what they do at that volume. What ever clipping or tone characteristics. This seems to be more like a master volume? Tubes aren't driven. Not the same thing. Let me know if I am wrong.

[@WaylonMcPhersonGuitar]

Thanks for that, I see what your saying, I explain the difference between this mod and an external attenuator on my Fourthwall page, link in the description if you want to check it out. Definitely way different to a MV, cheers!

[@nikolaprokop2228]

If the resistor is 680 ohms, what potentiometer and resistor values ​​should I use. Thank you.

[@WaylonMcPhersonGuitar]

The same, 680ohm and 100ka, cheers!