Marshall Tone Stack Mods

To test the mod before taking all of the parts out, you can unsolder one leg of R19. Then the tone stack has a useful bass control which also makes the midrange control more musically useful. marshall Class 5, truelya class A amp, with true tube saturation Barely used, This Amp is no longer in production, so this is now a Collector's Item. The kit uses a 12AX7 preamplifier tube, and a single EL84 output tube with solid state diodes for power rectification. Uses four KT-66 output tubes. Using data compiled for The Official Vintage Guitar Price Guide 2011, we continue the celebration with a list of the 25 most valuable amplifiers – those that helped create the tones made famous by virtually every genre of pop music. Marshall 9100 power amp with the bottom of the enclosure exposed, revealing. Below: 1952 FENDER Champion 600 needed general overhaul and tune up. mods for the Blues Jr. Guitar Amps; Guitar Amps. The physical swap is quite straightforward, and the only mod to the chassis is to drill another hole in the top to mount the 125ESE, due to its larger footprint. Because the amp most people have an image of in their heads is the iconic Marshall JCM800, one of the world's most popular and widely recorded amplifiers. The output impedance of a cathode follower is lower,and you get better bass response. marshall VS100 Valvestate Guitar Amplifier. The Contour knob seems to scoop out the mids when turned up high, and maybe boost them a tiny bit when turned down low. If anyone has any ideas or has tried something like this out before, please let me know the results. The bass knob is more of a fixed-freqency gain control. There were many amps to choose from in the ‘60s, but the Marshall brand seemed destined to make history early on. It’s like the old Shiva models but with a few mods that make it a stronger product in my opinion. This is totally separate from the normal channel which is stock Fender. 5 to 3 (9:00). Anything above 5's on the treble and bass are going to yield a mid-cut. The MOD 102 guitar amplifier is a low-cost ($215) vacuum-tube kit sold by Amplified Parts of Tempe, AZ. This is the standard Fender/Matamp/Marshall (Most others) tone stack. With sound that could fill a stadium, the Marshall tone caused many guitarists to aspire to stardom. If you bypass it, your tone should sound a LOT better. Great highs and slightly reduced bass. What it does have is every combination of 100 watt JMP variation from the Plexi to the mid seventies Super Lead and Super Bass heads. The normal channel inputs are no longer connected as it's now a 1 channel amp. mods for the Blues Jr. Stock, I dialed in an OK bass distortion tone with tone about 11:00, level about 1:00, and distortion about 3:00. I'll probably use the worthless "texture" control for the FAC. They were simple straight forward amplifiers. A Blues Junior makes a nice platform for gutting out and building a new circuit inside which is my preferred method of modification. Strat + Modded 200-Watt Marshall + Boost = Wood. amp's guitar speakers. Like the original Marshall it has simple preamp with just tone and volume controls and a no-frills cathode-biased 18W power stage. your tone stack down to work at the higher impedance that you get running it off the plate. It is a scooped sounding amp and the mid range is not very present whereas Fender has. marshall Class 5, truelya class A amp, with true tube saturation Barely used, This Amp is no longer in production, so this is now a Collector's Item. (It’s a dead-on reissue Marshall® did with crazy cool custom-made–vintage-recreation speakers and dual transformers to transfer the load of the 4 EL-84s!) The El Rey covers a lot of classic British amp tones by featuring two gain modes with the Power Toggle. 25uF capacitors in the tone stack, and the. I mostly use single coils on it and run the mids higher and the treble a little lower on these amps for fat classic rock tones that work well for rhythm and leads. Bright switch, bass boost, cold clipper switch, raw tone stack switch, Bassman/2204 Neg Feedback switch. The Bass, 2015 is the 50th anniversary of the Marshall stack. Look at the far left of the circuit board. Those looking for the true Marshall sound only need use an original, unmodified Super. I'm probably going to turn that cold clipper preamp stage into a cathode follower and the tone stack into a James with mid shift. What is VHT thinking? Why didn't they just add the knobs to the tone stack and skip the other tone control?. For those who are looking to purchase a high-quality Marshall amp—without breaking the bank—the 15-watt combo amp is the best Marshall amp to consider. Well, to the phase inverter, but single-ended amps don't have those so it's moot. Btw, its the mods Zakk used on "No More Tears"(The GOOD Zakk tone )!. I tried this out and it gives a good deal of accent to the sound. Most tone stacks, including the one in the Special 6, will provide a dip in the mid frequencies known as a mid scoop. Marshall Diagrams, Schematics and Service Manuals - download for free! Including: 5x02 new , 18w new , 18wr new , 30thanniv new , 87x 60 02 1 new , 87x 60 02 2 new , 100w 67 new , 200w new , 1917 new , 1930 new , 1959 01 60 02 new , 1959mk2u new , 1959prem new , 1959pwrm new , 1959sprm new , 1959spwm new , 1959t 66 new , 1959tu new , 1959u new , 1962ri89 new , 1962ri93 new , 1963 70 new , 1963. "On the high-gain channel diodes are used for gain/clipping. With the lower mids on a “Deep” knob, the tone controls are very nice and should be enough to please any tweaker. amp's guitar speakers. It's harshness is coming around 2. This modification is obviously deliberate, and it has substantial effects on bass and low-midrange response. Anything above 5's on the treble and bass are going to yield a mid-cut. that will affect how the signal hits the phase inverter and power amp. Electronic amplification entered the scene in the 1930s —when. Mods On A Marshall 3005 lead 12 Start by swapping op-amps, you can use all the op-amps that are used with Tubescreamers and they can all be found on ebay,. The Trinity Amps Custom Plexi is a 6V6 powered amp authentic to the Marshall 1959 Super Lead Plexi and it does sound excellent. Enter the DS-1. Gerald Weber also says he's seen a lot of amps this way, but he personally prefers the. The Original Electronic Music. The preamp is currently fairly awful. At low gain settings most of the signal is passing through gain pot by-pass cap (bright cap). Do phase inverter tubes effect the sound of my amp? get it then you'll not have any issues with tone. This comes before the tone stack and provides a different effect than just turning down the tone control. This part of the circuit is most commonly a combination of three potentiometers (for bass, mid, and treble knobs), three capacitors, and a resistor called the slope resistor. Shifts the tone stack frequencies to upper mids. Wow, that thing is all about tone. Change the voltage divider to a 1 meg and 220K. It’s an easy-grab, club-sized rendition of the 50-watt 2204 and 100-watt 2203 models that is likely to appeal to many of us who stride the music scene’s lower-volume stages these days. Loud clean, loud dirty, bedroom vol, it does it all. Gonna try the James!!!. Mod your Bassman reissue for vintage tone To start I´m sorry to point out that this here will NOT turn your Bassman reissue amp into an original, it´s NOT a 1:1 copy and it is NOT exactly sounding like the old, most sought after 5F6A Bassman version with the 4x10" speaker open cabinet. That's how good those original disc caps were made. The tone stack has a very wide range and we have found it works great with all types of pickups including active. So just plug in, hook up your big speaker stack, and start another rock revolution with the Marshall 1959HW tube guitar amplifier head! Marshall 1959HW Tube Guitar Amplifier Head at a Glance: A handwired Marshall legend. I don't necessarily think a Plexi or JCM800 sounded better than the JVM, but they had their own voices and that's something I wanted alongside the JVM, so I determined the necessary mods to get that and did them. Browse the back catalogue of Marshall for some of our most popular discontinued guitar and bass amps. Marshall Super PA. Blackheart BH5H Little Giant 5watt head and 1x12" cab (Bad Transformer. the 5532 removes almost all the solid-state fuzz from the bass frequencies. That boost is added to the boost my Marshall style amp produces if I have the tone controls on the amp set to the center. Most amps have one or the other but not both. One is to clean up the OD tone stack; the other is to literally change it to a Marshall tone stack, a much more radical, but equally good change. The Marshall Super Lead Model 1959 is a guitar amplifier head made by Marshall. At the least, replace the. • The Bright Cut mod takes out a little bit of sparkle in the feedback/clipping section. Got a request for a Baxandall tone stack daughter board, (much like the Big Muff Tone Stack daughter board) and thought it was a great idea as it's a great tone control. Marshall 100JH. Fender 68 Deluxe Reverb vs. Marshall amplifiers from this period were known for their simplicity in design and awesome tone. The mod R10 2k, C4 0. If you do not see your amp listed please contact us!". I first did this to compensate for the JVM having lower value treble and mid pots than a traditional Marshall, which shaves off a little more upper mids and I thought it was a little known way of addressing this (Santiago, have you been. The 5150II is a 5150 with an improved clean channel, and a modified distortion channel. Too much gain and it doesn´t sound pretty anymore. Cabinet suggestion: 1x12 or 2x12 Brit. Guitar Amps; Guitar Amps. Read honest and unbiased product reviews from our users. We added a tone stack that you can switch out and a mid. The following Marshall Super Lead tone tips and tricks will enable you to get much more versatility out of this legendary amplifier. The result of the mod is a fatter sound with more bass and adjustable bias. The Trinity Amps Custom Plexi is a 6V6 powered amp authentic to the Marshall 1959 Super Lead Plexi and it does sound excellent. But there are many players out there who don’t need clean tone and, in their mission of rock’n roll, have modified the Champ with a switch that disengages the tone stack to get a loud and hugely distorted Marshall/Tweed tone. Using data compiled for The Official Vintage Guitar Price Guide 2011, we continue the celebration with a list of the 25 most valuable amplifiers – those that helped create the tones made famous by virtually every genre of pop music. Switchable Tone Stack February 27, 2010 admin Mods The two main tone stacks used by Marshall over the years was first the 56k slope resistor and 250pf capacitor combination – this was used exclusively until 1968 on all their amps. The MOD 102 guitar amplifier is a low-cost ($215) vacuum-tube kit sold by Amplified Parts of Tempe, AZ. The mids are quite pronounced as well. 1uF bass cap), the amp sounds very very sharp. Or use (or combine with) Marshall greenbacks (4x12 20w or 25w). Let your ears decide. The Fender/Marshall/Vox TMB (Treble Mid Bass) tone stack has been around since the 1950's and has become a staple with Fender and Marshall amps. The previous tone stack was a little limited, so it was tuned up to have more range and provide a realistic, interactive response. Decided to modify the tone stack and use better components for increased articulation. The only problems were volume, hum, and tuning -- *not* tone. The last mod is not for players that like the nice, clean blackface tone. Read honest and unbiased product reviews from our users. To make this model feel more like a full amp, the power amp from the Fatality model (mesa rectifier mod) was added then tweaked slightly to reinforce the overall EQ curve of the Big Bottom. I guess the mods I'm looking for are mods that make the mid knob more versitile. What it does have is every combination of 100 watt JMP variation from the Plexi to the mid seventies Super Lead and Super Bass heads. I use a pre-phase inverter master volume paired with a 270k phase inverter grid stopper The Tone Stack Bypass Switch is an easy mod that removes the. At this setting the whole tonestack is reduced to three components. Marshall Tone Stack Mod The current Randall SL+ as well as the original single channel Egnaters have the original Marshall mid circuit with less mid-range than the JCM800 amps. Some also like to use a 250pf cap in the tone stack instead of a 500pf. Sounds killer. The bass knob is more of a fixed-freqency gain control. To further enhance the lifetime of the ECC82 driver stage tube, the stock 39kOhm anode resistors were raised to 47kOhm and up to 56kOhm in the second series. I haven't tried any of the mods yet but will probably give replacing the ceramic caps in the signal path a go sometime (and the elec caps in the power supply), doing that to my Marshall 9005 improved the tone a treat. If your browser opens/runs program files, the installation will be automatic. The Marshall JMP50 Model 1987 tone stack lowers the value of R 1 by 41 percent, from 56k to 33k. Re: Blackface Bassman Marshall Mods DannyR8, I have never done this to an AB165 or later Bassman, but I do it to two channel FEnder reverb amps' Normal channels often. Three band EQ is nice thing to have and it follows the basic principles of the tone controls found in Marshall amplifiers. noise performance is better too. amp's guitar speakers. and many foreign countries. It's a three channel amplifier with four EL34 and four 12AX7 tubes that features independent controls, a midboost, deep switch, tone shift, power reduction, output mute, reverb, line out, effects loop and more. Measuring just 16. As we know, the Marshall JCM’s distortion channel is an icon in the rock and roll world. The tone stack is one of the main things that gives an amp its particular voice, as it shapes the frequency response pretty drastically. This Mod is really more of an upgrade. This Gibson Goldtone GA-5 might just be the best sounding GA-5 around. Treble/Bass tone stacks usually have a "tail" resistor that connects the tone stack to ground, like 6K8 for Fender Princeton (in the case of the Twin Reverb, it's a 10K Mid pot), or higher value for Marshall (like 25K Mid pot). The choice of the 1959 Bassman was inspired by the book Circuit Analysis of a Legendary Tube Amplifier: The Fender Bassman 5F6-A by Richard Kuehnel. The mid controls more of the overall contour of the entire tone stack. So here's a basic overview of how amps work and what you can do to start tweaking your own. Many different tone stack implementations exist, but this design uses what is known as the FMV tone stack. The tone stack is much like that in Marshall guitar amps. Even without a huge bottom end there are enough mids and screaming highs to cut through in most bands. The roaring Plexi tone is the stuff of legend, with its muscular crunch Lead (Marshall®-. The anode and cathode resistors were removed in the second series. This is why a Marshall has been the sound of rock for decades. Why hello! It is our old friend, the Fender/Marshall tone stack, as it appears in a Marshall JCM800. amp's tube power amp. The last mod is not for players that like the nice, clean blackface tone. I use a pre-phase inverter master volume paired with a 270k phase inverter grid stopper The Tone Stack Bypass Switch is an easy mod that removes the. Tone Stack - I left the tone stack alone as this is the basic Marshall Tone stack and is a good fit for this amp. A Blues Junior makes a nice platform for gutting out and building a new circuit inside which is my preferred method of modification. In this build the pot gound buss wire has been elevated above the pots, and is grounded to a lug below. It had a bit of a raspy low end. All in one. The classic Marshall Stack consists of one head containing the actual amplifier, on top of two stacked 4×12s, which are loudspeaker cabinets each containing four 12-inch loudspeakers arranged in a square layout. So you'll need to download the FREE Adobe Acrobat Reader via the link below to be able to view schematics. "On the high-gain channel diodes are used for gain/clipping. Read honest and unbiased product reviews from our users. Pentodes 204 Beam Power Tetrodes 205 Generalizing the Amplifier Circuit 206 Preamp Tube Substitution 209 Bypass Capacitor Modification 210 Plate Resistor Value 213 Volume Control and Mixing Circuits 214 Second Stage Frequency Response 219 Marshall Modifications to the 5F6-A Tone Stack 221 Tone Stack Low Frequency Response 222 Tone Stack High. • The Hard Clipping mod is taken from the King of Tone and allows you to add hard clipping after the standard diode clipping section. It’s a fact that Mesa Engineering uses two modified forms of the Marshall tone stack for their Dual Rectifier series. Modification price: 199,00 €. The earliest non-master volume Marshall models can even provide additional fattening of the low-end frequencies by way of the tube compression as well as through mild speaker distortion. Reviewed by Guitarist magazine in the UK and given the line, "Shredders, here is an amp you won't need to have modified," this move by Marshall was again an outgrowth of musicians' desires, featuring more distortion than ever and retaining popular aspects of the late JCM800 models. Not wanting to do anything radical in the tone section, I chose to use a Fender/Marshall/Vox tone stack. A damaged Marshall Super PA. Gonna try the James!!!. It is a scooped sounding amp and the mid range is not very present whereas Fender has. Tried and true, it has fairly high gain loss and big mid scoop. With sound that could fill a stadium, the Marshall tone caused many guitarists to aspire to stardom. Marshall Tone Stack Mod The current Randall SL+ as well as the original single channel Egnaters have the original Marshall mid circuit with less mid-range than the JCM800 amps. Here's a controls pre-adjusted MG100DFX curve in blue against a Plexi curve in yellow:. Our line is a unique blend of no-rules engineering and artistic whim, from our affordable Vexter series to our hand painted and custom designed items. Rock and blues players that don't use the squeaky clean sound will love this. When replacing a 250k bass pot an 82k resistor works pretty well simulating a pot in the center position. I would like to change this feature as it is way too fizzy when it breaks up. b) Marshall - use MOSFET cathode follower after first stage, Plexi tone stack plus cathode bypass and coupling cap values. Good for ribbon cable replacement ! Your mod changed the way the tone stack reacts, there are many mod you can try there, and listen to the result. amp's guitar speakers. I haven't heard this mod in the flesh but i'm thinking of having it done to mine. This amp uses similar tone stack as in Fender Blackface amps. The Speed is now a tone control and the Intensity becomes a master volume. Marshall have stockists all over the world on the internet and in store. Look at the far left of the circuit board. The CeriaTone and name, logo and related trademarks and service marks, owned by CeriaTone. There is not a great amount of boost/cut available. A Blues Junior makes a nice platform for gutting out and building a new circuit inside which is my preferred method of modification. I've got a Marshall Class 5 I picked up on craigslist a while ago. The 5150II is a 5150 with an improved clean channel, and a modified distortion channel. See the lead channel/mid mod, this a simplified Marshall stack (cap and resistors) having a typical setting soldered into the circuit. This combination creates a dynamic, touch-responsive medium-gain amp that’s perfect for blues and classic rock. It was simply the tone of a stock Marshall head and cabinet with a stock Gibson and Strat. It also upgrades the tone stack and adds extra filtering to the high voltage power supply. This allows the flexibility of being able to boost or cut bass and treble. It will turn your amp in to the more Ampeg VL/Metaltronix kind of range. after some research and finding Vic Steffens(engineered and mixed. Paul, Minnesota, and beyond. We added a tone stack that you can switch out and a mid. 68uF cathode bypass cap on the first gain stage with a 5uF cap. The mod also slightly increased the gain of the amps. The normal channel inputs are no longer connected as it's now a 1 channel amp. It depends on how the master volume is implemented. Marshall Super Bass 100w Schematic In the first installment of our Marshall Shopper's Guide, we take a look at vintage A Super Bass from the same era will have just a hair less gain and in fact will. Peavey Windsor Studio Mods and Problems Tone stack mod I modded the tone stack on mine to resemble marshall's design. still that nice Marshall crunch and mid range, but much more "omph" to it. I have converted the amp to a Marshall tone stack and other suggestions you’ve made very successfully, but found nothing on tapping into the unused gain stage for the bass side. Click on the "services" button above for more info. good power attenuator. Add a 5uF cap across the second stage 10K resistor. Fender, Marshall, and Traynor Tone Stacks I’ve recently begun recording a second disc with the band I’m in, Shayna and the Bulldog. Got a request for a Baxandall tone stack daughter board, (much like the Big Muff Tone Stack daughter board) and thought it was a great idea as it's a great tone control. com without the expressed permission of PedalMonkey is prohibited. 20 years, a whole bunch of amps, and many years of retail experience later, the 6100 always stayed in my mind as my favourite amp that Marshall ever made. So just plug in, hook up your big speaker stack, and start another rock revolution with the Marshall 1959HW tube guitar amplifier head! Marshall 1959HW Tube Guitar Amplifier Head at a Glance: A handwired Marshall legend. Guitar Valve Amplifier Mods and Modification - Power Scaling - Effects Pedals, and Carbon Fibre Guitars. Wow, that thing is all about tone. stock is very rock amp, it spots a typical marshall style tone stack with fixed resistors instead of pots. Verdict, I hate it. Blackheart BH5H Little Giant 5watt head and 1x12" cab (Bad Transformer. The Marshall MG10CD Combo Amp is a great amplifier for the studio, too. Strat + Modded 200-Watt Marshall + Boost = Wood. I changed the values in the distortion plus part of the circuit to stock d+ values with a bit more low pass filtering. What it does have is every combination of 100 watt JMP variation from the Plexi to the mid seventies Super Lead and Super Bass heads. Just for fun I put an old Carvin 7 band EQ in front and dialed out the harshness pretty easy. One thing to note - NONE of these involve modification to the original Marshall circuit. Fender TS gives too much bass. 1uF tone cap, and a new 0. If you are looking for some blazing Marshall tone without resorting to fuzz pedals or using a Hot Plate TM, you are in the right place. A 1meg linear pot has been added temporarily to dial out the tone stack. While its possible this. For a comparison of the response curves of different tone stacks, Duncan Amps has a Tone Stack simulator the is really nice. Its 15W head and 2 - 10" speaker cabinets create a stack that is only 15"W x 37"H x 9"D, but the Marshall MG15MSII Micro Stack puts out a tone that's far from. Got a request for a Baxandall tone stack daughter board, (much like the Big Muff Tone Stack daughter board) and thought it was a great idea as it's a great tone control. Usually we think of the full Marshall stack, with 50, 100, even 200 watt heads driving multiple 4×12 cabinets. There are many portable amps to choose from these days. b) Marshall - use MOSFET cathode follower after first stage, Plexi tone stack plus cathode bypass and coupling cap values. Reviewed by Guitarist magazine in the UK and given the line, "Shredders, here is an amp you won't need to have modified," this move by Marshall was again an outgrowth of musicians' desires, featuring more distortion than ever and retaining popular aspects of the late JCM800 models. marshall Class 5, truelya class A amp, with true tube saturation Barely used, This Amp is no longer in production, so this is now a Collector's Item. Sounds killer. This is totally separate from the normal channel which is stock Fender. i'm always disappointed when i find the truth though. Four ECC83s in the preamp section (in concert with the amp's gain/master volume arrangement) give you stunning tone-shaping mojo, and with two 6V6s in…. We also repair many solid state and hybrid guitar and bass amps. Tube amp hall of Fame sites 1 to 10. these were some of the mods that were suggested for this build by stratman7000 on diysb 1) Remove the 470pf Cap from input stage. still that nice Marshall crunch and mid range, but much more "omph" to it. I went with a 100k pot and a 33k resistor on each channel. I'm thinking of replacing some of the components of the tone stack to allow more highs to pass through the circuit, but I'm a bit concerned that it will have a negative effect on how the controls work in the stock configuration. Using data compiled for The Official Vintage Guitar Price Guide 2011, we continue the celebration with a list of the 25 most valuable amplifiers – those that helped create the tones made famous by virtually every genre of pop music. The normal channel inputs are no longer connected as it's now a 1 channel amp. The tone stack can be re-worked so it is not so muddy on the bottom. A 15-watt tone beast Marshall's DSL15H is an all-tube, twin-channel tone machine capable of conjuring any classic Marshall sound - past or present. 5, Bass to 2. Contact Me. Treble/Bass tone stacks usually have a "tail" resistor that connects the tone stack to ground, like 6K8 for Fender Princeton (in the case of the Twin Reverb, it's a 10K Mid pot), or higher value for Marshall (like 25K Mid pot). It's harshness is coming around 2. Read honest and unbiased product reviews from our users. When flipped all the way down, the Treble knob unactivates the tone stack. Chane Audio, Westport, ON, serving Ontario's musicians, amp and guitar sales, repairs, mods, new and used guitars, amps, PA gear, open Saturday 9 to 5, by chance or appointment through the week. This comes before the tone stack and provides a different effect than just turning down the tone control. At the least, replace the. Then the tone stack has a useful bass control which also makes the midrange control more musically useful. Windows Setup: Click here to download the tsc_setup. these were some of the mods that were suggested for this build by stratman7000 on diysb 1) Remove the 470pf Cap from input stage. It was simply the tone of a stock Marshall head and cabinet with a stock Gibson and Strat. 20 years, a whole bunch of amps, and many years of retail experience later, the 6100 always stayed in my mind as my favourite amp that Marshall ever made. This Gibson Goldtone GA-5 might just be the best sounding GA-5 around. Since you've got a nice low impedance going into the stack, it really works, even with the gain cut substantially more than a 1987. At the least, replace the. I loved that thing before the GAS attack struck (some things never change) and I traded it in to buy a Soldano Hot Rod 100+. #, Marshall Schematics 75, Marshall_jcm800_splitch_rev_50w_4210. The amp's two channels, which can be blended together using the two volume controls, offer different tones—Channel 1 has a fairly flat tonal response, while Channel 2 is somewhat darker-sounding. I went with a 100k pot and a 33k resistor on each channel. The only problems were volume, hum, and tuning -- *not* tone. Slash has always been associated with Marshall amps and has used various models over the years including two signature heads: the Marshall JCM 2555 Slash and the Marshall AFD100 which is supposed to capture the tone from the Appetite For Destruction era. 2000+ profiles that cover American Blackface and Tweed cleans, British Top Boost, Normal EF86 style chime, Plexiglass grind and tons of boutique edge of break up tones. Change the pots to mil spec as the replacements have a life of about 5 years. Changed C10 - V4/V5 cathode bypass capacitor to 50uF 50V. MOD 101 DIY Guitar Amplifier Kit. When Marshall copied the Fender 5F6-A Bassman almost verbatim to create the JTM45 amplifier the Fender TMB tone stack came with it and it's still being designed into new amps today. Covering the primary mods: Clip 1 leg or remove both the C4 (treble peaking circuit) and C5 (bright cap). The function of an elaborate equalizer in a sophisticated stereo system is to compensate for the frequency response characteristics of the amplifier and speaker system so as more closel. 1 uf cap put around the "top" of the EQ (from the input of the EQ to the output leaving the 250K Treble control) will do the trick. 1 gain stag e going into Volume Pot going into power tube, that's it. i know,once a tone chaser,always a tone chaser. I sometimes make these amplifiers into the typical ‘classic’ circuit seen in ‘Tweed’ Bassman and Marshall amplifiers. The design of the JCM800 1986 and JCM800 1992 amps departed from the "classic" Marshall Bass amp design and incorporated a better tone stack with a mid sweep and a slope control not found on the older JMP 1986 and JMP 1992 amps. I decided to try it but with a mini toggle so I could check the differences. You'll lose about 3dB of voltage gain, but that is no biggie, just turn the master up a bit more. A couple weeks ago I got a Vox ac15c1. don't know if anyone is following this thread, but some observations as i mod this thing: the tone stack is a bit different, but with the 5532 op-amp it pretty much nails a JCM800 preamp. and many foreign countries. Fender saved the blocking cap in front of the tone stack (like other makers). The mid shift mod can be done to any amp with a Fender/Marshall/Vox style tone stack. Check it out. Or try the AC30TB tone stack (Bright on) Wikipedia; Vox forum; TOP BOOST = VOX AC30TBX TOPBOOST. The Original Electronic Music. It's been awhile since I've done any "How To" blogs, so I thought I'd do one where I provide a schematic and layout for a prototype of a two channel, foot switchable hot rod Marshall style amp. The bass channel adds a gain stage and a different sort of tone stack which is similar to what Fender did with the 6G6, 6G6-A, and 6G6-B versions of the bassman head. Add a 5uF cap across the second stage 10K resistor. Find helpful customer reviews and review ratings for Catalinbread Formula 5F6 Tweed Bassman Overdrive Guitar Effects Pedal at Amazon. This amp uses similar tone stack as in Fender Blackface amps. Change the pots to mil spec as the replacements have a life of about 5 years. 68uf over V2a Rk, and the 56k/250pf or 33k/500pf tone stack. Some forum members asked if their Blues Junior amps could be modded for more Marshall like tonality so I put together this mod which is designed to impart more of a Marshall drive and punch to the Fender Blues Junior amp. That way I'll be able to switch between shared/split, 330uf or. The two black lines are the original tone stack, Treble set to 5. This kit is for the Included in this kit are the following upgrades: Tone Stack - Replace the wimpy Bass and Mid caps with WIMA Box Caps with corrected values to open up the tone and get rid of that boxy sound. Which ones? New output tubes? Which ones? More gain in the preamp. This can be done by changing the following: Change R13 to 56K Change C6 to 220pf - Grit Control Bypass Cap - Add capacitor bypass around the grit control to add highs. Enjoy lots of harmonics, headroom and tone definition with awesome signal depth and harmonic structure. Peavey 5150 / 6505 series mods. Mid Shift on Clean, OD1 & OD2 - Very useful mods. This provides a greater range of adjustment of the tone controls. So along with any possible tone mods I think going back to a closed cab will help too. To me, a JTM45, while a really great amp, isn't the tone I think of when I think "Marshall". Marshall Super PA. Ok maybe not a Marshall mod but a Hiwatt. This comes before the tone stack and provides a different effect than just turning down the tone control. The treble knob is less of a gain on a fixed frequency than shift between an upper mid and a treble boost. Others may think of a DSL2000 or who knows what else. I used Mallory 150's and silver mica caps and 1W carbon film resistors. My Studio mod has no overdrive mods and no masters. The 1974 has a distinictive voice of it's own, it doesn't sound like the big Marshalls, so mods and variations quickly became popular. Change the pots to mil spec as the replacements have a life of about 5 years. Fender saved the blocking cap in front of the tone stack (like other makers). The normal channel looks and sounds like the normal channel on other blackface amps (relatively speaking). It's tone stack, tube configuration, preamp and power section has inspired numerous amps builders including Jim Marshall, the founder of Marshall amps, who used the Bassman tweed 5F6-A circuit in 1958-1959 as template the legendary Marshall JTM45. The two black lines are the original tone stack, Treble set to 5. Wired to Marshall 2204 specs, cascade preamp, Marshall tone stack, TMB tone stack, presence, gain, master volume, with one input only. Guitarists who were part of the new wave of British heavy metal loved the tight, aggressive tone of the newer hybrid amps. Treble/Bass tone stacks usually have a "tail" resistor that connects the tone stack to ground, like 6K8 for Fender Princeton (in the case of the Twin Reverb, it's a 10K Mid pot), or higher value for Marshall (like 25K Mid pot). 99 - $3,049. If you want a Bassman to sound like a Marshall, you can do John McIntyre's Bluesmaker mod which changes gain staging, tone stack, adds a cathode follower, 12AX7 PI and EL34's. These amps were handwired and are easy to mod to improve the sound. This part of the circuit is most commonly a combination of three potentiometers (for bass, mid, and treble knobs), three capacitors, and a resistor called the slope resistor. The bass knob is more of a fixed-freqency gain control. Although it sounds not too bad after the mods, it will get less….