Rocking in the Plexi world

Plexi Drive for classic plexi tones

1962 was the year that really changed the face and sound of rock'n roll. Not because the Beatles started gigging in Hamburg and not because Maestro issues the first fuzz-tone. More than anything, it was because Marshall first released their JTM 45 30W model. This early rock monster was heavily based on the Fender Bassman but using a 12AX7 tube for pre-amp and used KT66 tubes for the power amp driving a closed back 4X12'' celestion speakers cabinet. This little differences from the original Bassman had a huge impact on the sound and made Marshall a quick predecessor for the older Bassmans and VOX AC50 which were the power horses for early rock'n roll outfits in the UK.

Again, not directly related to the world of fuzz but definitely a cornerstone on the quest. Fuzz, as always, is just fingernails on a chalkboard without the right amp to smooth it out. Marshalls with treble boosters, Fuzz Faces, Octave fuzzes and more.

The JTM name is the acronym for Jim & Terry Marshall. The 45 is for the 45W series which was the upper limit at the time after the 30W series and before the 50W and 100W appeared.

The real deal JTM 45 head MKII

In the mid-60's The JTM 45 became the staple sound source for blues rock bands across the world due to its long sustain, crunchy leads and edgy cleans. It had this edge over Fender and Vox and continued to develop, giving birth to legendary offsprings such as the Marshall Bluesbreaker made famous by Clapton's sound with the Bluesbreakers on the Beano album (hard driven by his Gibson ES-335 and a Dallas Rangemaster), and the powerfull Marshall 1959 Plexi Superlead. It can be regarded that with every generation of Marshall amps, guitar music evolved, from blues to rock to hard rock to metal and so on. The amps and styles are that much interlaced between them.

Number One - The Original 1962 model which the JTM 45 was based upon. 23 units sold and changed history. Today resides in the Marshall museum.

Hendrix used the JTM as his main amp between 1968 and 1969. Angus Young of AC/DC relied heavily on the JTM 45 for his signature guitar tone on early AC/DC albums and live concerts (though he also used the 100W Superlead). Early Gary Moore and Early Peter Green sounds also rely heavily on the JTM 45/100 as the source for their glass shattering solos. It seems that regardless of whether it were humbuckers or single coils, the JTM delivered great clean tones and super dynamic crunch. It takes pedals very well especially if those have a low cut like the Tube screamer or any treble booster. With the bass heavy Fuzz Face it seems strange that Hendrix could get what he got out of this pair,but I guess he did, didn't he? The strat definitely sounds better than the Gibson using this setup.

Hendrix, Page, Yardbirds, The Who, Blackmore and Angus Young.
All of them used a lot of Marshalls and at some point during their early life and their better days played a JTM 45.

The Plexi name came from the plexiglass panel which covered the front side panel on the early models since 1962. In 1967 this panel was replaced with a brushed aluminum panel but the name "plexi" remained as the one-word-description to describe that signature tone to this very day.

Some really great info can be found around the web and here are a few examples:

http://www.legendarytones.com/marshall-shoppers-guide-1/

http://www.marshallamps.com/history/

Anyway, Since I first built the Runoffgroove Thor I have been trying endlessly to nail those early rock tones using various pickups and various rig setups. I did succeed getting a lot of that crunch I wanted but something still kept me up at nights.

1. I couldn't get those clean glassy tones from the Thor, probably because it was a high gain pedal meant to emulate the Superlead 1959 tones.

2. It had some hiss which made it hard for me to use it as the last link in the chain using fuzz pedals or other overdrives.

I had a 2 year tour around every forum known to man, played a lot of MIAB (Marshall in a box) pedals and spent many YouTube hours in order to really understand what pedal I want to build for that particular crunch. I ended up with several candidates all of which try to emulate the Plexi mid-gain overdrive and eventually decided to build the Wampler Plexi-Drive. The reason was two fold: 

A. I had more experience building the Plexi-Drive having built it in the past for a friend and it sounded great what I tested it against the Thor, although not as powerful, of course.

B. It uses standard components like J201 FETs and biasing them using trim pots made it easy to build without too much voodoo.

So, after waiting about a year after, finishing several other DIY projects I came around to this project and after a few evening selecting parts, soldering, assembling and paintings it was done.

Now the Plexi-Drive has a younger brother called Plexi-Drive Deluxe which is even more flexible and has more tone control. The schematic is still not around so I decided to give my Plexi-Drive some mods after searching the forums for some help.

Gut shot of the Plexi Drive based on the TagboardFX layout with biasing trimmers for the JFETs

The first mod I did was lowering the bass boost cap which emulates the 4X12'' cabinet. I ended up using a 1nF cap instead of a 2.2nF which makes the bass less heavy and more transparent. I guss it's a matter of taste and you can also use a 3 pole switch for more than two modes but for me it is enough.

The second is a 1uF cap bypassing the 1st gain stage by pulling the J201's source down to the ground. Although this seems like reducing the amp's gain, it actually boosts the gain up by increasing the volume and preventing the 1st stage from clipping the signal.

Now Brian Wampler indicated that this pedal is somewhere between the lower gain 18W tone and the mid gain JTM  45. I really couldn't tell the difference never having played any of the real deal amps but I can tell you for sure that this is the pedal that I was looking for when I started this Marshall quest. I wanted clean sparkly tones at lower GAIN settings and strong crunch at high GAIN settings with the TONE control compensating where needed. Usually this means that lower GAIN demands higher TONE. The LEVEL control gives you plenty of boost way way above unity and the extra switches give you some more versatility. Different pickups and different boosters really give you a lot of options here.

Mug shot of the modded DIY Wampler Plexi-Drive

I tried to give the pedal the same clean looks which the amp is known for with black and gold colors. I called the bass switch "Cab" and the 1st stage bypass switch "Boost" and now I have a modded Plexi-Drive giving me some great vintage classy tones. Finally I decided to go with a red LED which gives it some extra vintage Marshall looks.

 It sounds great with other pedals in the chain. A treble booster or an overdrive are great to drive it harder and it takes up fuzz pedals very good and probably best with single coils.

So there you have it. A really really great pedal with minimum noise, hiss and unwanted artifacts.

Below you will find 2 tracks that for some reason the Mixcloud shows only one and you can choose "next" to move on to the next one. The first one is to demonstrate the pedal with strong PAF humbuckers and the second with single coils. I play around with the volume knob, various pedal settings, bridge and neck pickups and even some wah or a treble booster in front on a few cases.

You can find the layout I used here:
http://tagboardeffects.blogspot.co.il/2013/09/plexi-drive-with-trimmers.html

The schematic is shown on the Revolution Deux page:
https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiAQlxZl1hMAz3UIwJYt9sUP9SkSAYqJKNbal_nigm2Uko5C1dopC5odZy8zuG8TOXNA-3ms9-x45urWOD_W42-uKIxhNA5FlnTKX6l_0Ysu8H_UqKFU1K94x4WcwD8Sfx4e_U09-Nt0YU/s1600/plexi-drive.PNG

Enjoy!

    

Plexi Drive by Doron Barness on Mixcloud

The Flying Rat

The 60's and early 70's were all about driving tube amps into overdrive heaven and on the way use fuzz and treble boosters to get the job done. Most Fuzz stompboxes were, in fact, so effective that you didn't really need the amps to be that heavily driven anymore, but they killed most of the guitar's tone and dynamics. They took over the sound (Fuzz faces and Big Muffs to name a few). 

As people got fed up with fuzzes and wanted back that dynamic distorted overdrive, Orange amde the first step and came out with their Overdrive amp in the mid 70's. That started the distortion race all over again. The idea of a stompbox giving you that distortion, which was so important for rock guitarists, yielded the next step in the second half of the 70's. In 1976 Amlyn Crowther designed the Hotcake which would become the first boutique overdrive (Sonic Youth, Pavement, Radiohead, Protishead and many other consider it their "secret weapon'). Japanese based Ibanez and Boss came out with the classic Tube Screamer and the OD-1 (DS-1 too), respectively, around 1978. In Kalamazoo, Michigan, two guys in a basement started selling custom ordered pedals under the Pro-Co name. Those were the first Rats. All the above brands produced pedals based around an operational amplifier and have some similarities in their designs. All three became classics and over the years got reissues, sequels and modified versions. 

I decided to build the Rat for 3 main reasons: a) It is a classic pedal and deserves FuzzQuest attention. b) Some of my favorite guitarists use it or have used it over the years. C) There is no real mojo in this circuit. the LM308 chip and clipping diodes are all pretty straightforward. No Germanium PNP or de-gooped old boxes with debates over them. The amount of schematics on the web is infinite and the mods are all given out. You can build the circuit with mods and it will sound just like the real thing. Even better. Guitarists who used this unit and made it famous were Thom Yorke, Thurston Moore, Stephen Malkmus, Bernard Butler, Marc Ribot, Bill Frisell, Frank Black, Jeff Beck, Andy Summers, Graham Coxon and Kurt Cobain, to name a few. If you told me only Thurston and Ribot were on this list, it would have been enough for me. This might have been the overdrive/distortion used by Ribot on Rain Dogs by Tom Waits. Imagine that!

The Multi Rat Schematic

So, I gathered about a dozen schematics I considered to be trustworthy. RG Keen and Jack Orman did some tremendous work given on the aron nelson archive and diystompboxes. You can download the schematic shown here, but Beavisaudio, GGG, Sabrotone, SoulSonic, Gaussmarkov and others, all have verified circuits readily available, just click the links.

I added the Ruetz mod to conttroll the highs and called it EDGE. Got an On/Off/On switch for choosing between the diodes, MOSFET clipping and clean boost and named it CHARACTER. DISTORTION  FILTER and VOLUME are similar to the original. Apart from that it's a vintage Rat clone.  The added mods give it a lot of "elevation" so I called it the BAT. Also I liked the Mokafix Bat VST emulation and adopted the name. It really is a mouse with wings.

So I got the circuit working and painted the enclosure. I really dig the sound which sounds pretty awesome especially with my English Channel emulation of the AC30. I completely understand why this became a classic unit. This is the distortion we grew up on listening to grunge, alternative and punk rock from the 80's and 90's. Great sound, versatile, easy to use. Humbuckers with an AC30 you get the British indie rock of Suede and Blur. Single Coils with Fender amps will give you Sonic Youth and Pavement flavors. Pretty Amazing. With the clean boost mod you can get great fuzzy overdrive and you can drive other pedals on the chain or drive your amp further. Super!  

As always, if you want audio demos you have to comment and ask for it. I hope to get some clips done for all my posts but it's gonna take a while since I am on a building mania and even posting on the FuzzQuest blog takes me forever.

Anyway, a very recommended build. Pretty easy and fun with a lot of options. With the Ruetz mod attenuating the highs and the clean Boost which is not so clean I got some wicked fuzz sounds. If you are wondering, you can be sure that a Tube Screamer clone is on the way. Naturally.

   

Tumble and Drive - the Rougue Dumble

The Runoffgroove Tumble Drive (Umble)

For those of you who are following this blog and my recent posts, it is probably clear that, although our main point of concern is the magical sounds of fuzz circuits, a great of interest is being paid to the accompanying peripherals, which have a great deal to do with the overall guitar sound. What I mean by this long phrase is that every time I think I have understood the fuzz sound of a certain pedal I am amazed to discover how different it sounds and behaves when you play with it through different amps.

That was the main reason I began building amp emulation pedals like the English Channel (emulation a VOX AC30 top boost channel) or the Thor (The Marshall 100W Superlead). You have probably noticed that when it comes to amp emulation I am very fond of the Runoffgroove design, and that is mostly because they just sound great and they definitely evoke the characteristic sounds of the amps they aim to emulate.

On of the most sought after sound of guitar amplifiers is the unique sound of the Dumble amps which have been made since the 60's in California by Alexander "Howard" Dumble. Although I have never played through a Dumble in my life, nor do I believe I will ever do, it was interesting to hear what the fuss was all about. The list of Dumble users includes some major players like Santana, SRV, John Mayer, Al Di Meola and Ben Harper and many more. Probably the most recognized user of the Dumbles is Eric Johnson who made the amps famous with his singing Fuzz Face going through an heavily overdriven Dumble.

Unlike many of the ROG designs which I built in order to get the well known classic sound of a certain amp, on this build I just wanted a good American  sound which would get me from clean to crunch with some nice lead tone and good tone control. I even asked the ROG guys about a Fender like design that would get me close to a Vibroking or a Super-Sonic sound and they recommended their Dumble-like design, called the Umble, a cascaded FET based overdrive. 

I quickly started gathering parts and had the circuit running in a few days....and YES....another great sounding overdrive by the amazing guys at ROG. This is a very versatile unit which got me playing for days getting some wicked tones. On the lower end of the DRIVE knob it's capable of some really sweet clean tones. Single coils come cleaner but with proper use of the tonestack you can get Humbuckers to sound clean too. I really love low gain pedals because I love the warm drive you can get from them. This pedal does it all, warm, punchy or razor sharp, it's all there. Once you get the DRIVE up it becomes a monster and reaches Fuzz territory towards the end. While lowering the Tone stack knobs cleans the sound, increasing them gives you more drive and half way through the dials you are already speeding on the freeway.

I called it Tumble Drive because it sounded better then Umble to me and it drives so smooth and nice.

The one thing which I really love about this design is that it also serves as an excellent booster before a second overdrive like the Supreaux Duo ("1st Page" on my blog). It sounds really good and gives you the Eric Johnson tone if you put a Fuzz Face in front of it. Actually, every fuzz I hooked up with it sounded great and so it isn't just another amp-like pedal. Although the Tone stack is a little strange to work with it sounds good: The TREBLE knob adds some BASS as you crank it, and the BASS is quite subtle.

The final thing I did just recently was adding a simple switch to bypass the first FET gain stage so that I can now get even cleaner sound on low DRIVE settings. Now it's just perfect and I really like the paint job which I got in the end with the IGNITE toggle switch.

The gain switch which bypasses the first stage gain FET (in red)

Umble with Gain switch

Again....don't pass out on this design if you are serious about american sounding overdrives. The schematic can be found here.

Below are 2 demos of my lousy playing on my ES335 clone guitar and the pedal through a soundcard and some amp with room simulations. The first is a demo with different settings and the second is a mix of 3 tracks, Riff+rhythm+solo, with various settings showing the versatile sound of the effect on a single guitar. It's quite an amazing pedal with its capabilities as a low gain overdrive, high gain overdrive, full on distortion and a great fuzz character with the BASS knob fully cranked. The tone stack have a huge effect on the sound of the pedal.

Tumble Drive - Umble on Mixcloud

Amp pedals - The ROG Professor Tweed

After trying a few fuzz designs I started investigating the gear chain of some of my favorite guitar legends and I realized that although the fuzz pedals are a critical part of the chain there are other components which are just as cardinal as the pedals. There is the brain, the heart, hands and fingers and feel of the player. There are the strings, obviously, but once the vibrations are created they are turned to electric current through the pickup coils which are the first major factor in the sound. Mostly you can hear the difference between single coil pickups and Humbuckers. After that you have the pedals, the amp, the cabinet and speakers and the room, microphones and recording gear.

It seems after building some fuzz pedals the next gain stage is the amplifier. I have to give a big credit to the RunOffGroove website from which I learned so much. The guys over at ROG have some fantastic designs of circuits utilizing solid-state FETs to emulate the behavior of driven tube gain stages. With this they designed some serious emulations of classic amps by Fender, Vox and Marshal.

As part of my Fuzz Quest I started off with the simplest design of a classic Princeton amp so I built the Professor Tweed. It sounds like a late 50s amp which can go from clean to overdrive through the input GAIN knob. This was the first time I understood the difference in voicing quality and character between an overdrive and a fuzz. A fuzz is really over-the-top distortion which changes the original sound completely. The overdriven amp stage is softer and crunchier. Although the pedals sound great together with the fuzz boosting the input of the amp pedal, you can use the amp pedal alone as a great overdrive for guitar or Harmonica and it really gives you great classic Blues and Rock'n Roll tone. I have to say that the Professor lacks some sparkle and I always keep its TONE control on max. The mo' bass switch is a nice addition too. I ended up using additional tone control pedal after it to give it more sparkle. Also it sounds better with single coils than with Humbuckers. Humbuckers tend to have higher ouput level and drive the pedal to distortion even at low gain settings. You can get the schematic here.

In the next few posts I'll dive some more into overdrives as it really is part of the story.