Plexi 50 build

Here's a crazy question:

I've always wanted a crunchy Marshall tube amp but never really was committed with the funds. I settled for a 50w solid state Marshall years ago. I was disappointed from day 1. Not to mention the amp had an intermittent short which the warranty provider could never find. I love Marshall's crunchy sound, but not so much their clean sound. And certainly not their intermittently-shorted circuit board sound.

Long story-short:

Is it possible to build an amp with Marshall's '68 Plexi 50 circuit using only the crunchy side, not the clean?

I've been working on an 18W TMB, (well it's been sitting in the cradle for a while). It deletes the trem, and adds a TMB circuit from the JCM800. I'm pretty sure the Marshall crunch is there, we'll see about anything close to clean at volume!
Really, this month I'm gonna order the last parts I need and finish it, No Really!

https://www.18watt.com/storage/18_Watt_TMB.pdf

Disclaimer: guitar amps have lethal voltages. Proceed with caution and be well versed in amp safety.

That said about 15 years ago I built a 5F1 circuit tweed champ in a bigger cabinet with a 10” speaker and I love the damn thing still. Weber speakers makes good amp kits.

Proceeding with caution, thanks. I'm basing my urge on a Jamup Pro app I bought a few years ago. Never actually played through a Plexi. The app has several Marshall models. Although I am aware it's not the real thing, this little app is pretty awesome. The best sounding Marshall model by far on the app is the Plexi 50. From what I've read, the Plexi more or less defined the Marshall sound back in the day.

I have a 50w solid state Marshall which hasn't worked for years. I was thinking I could maybe reuse some of the electronics as well as the housing and chassis and build a decent tube version for less than a fortune. ...And kind of recycle at the same time. I just got this brainstorm today, so just beginning my research.

Quote:

---

Originally Posted by musicallydeclined

Proceeding with caution, thanks. I'm basing my urge on a Jamup Pro app I bought a few years ago. Never actually played through a Plexi. The app has several Marshall models. Although I am aware it's not the real thing, this little app is pretty awesome. The best sounding Marshall model by far on the app is the Plexi 50. From what I've read, the Plexi more or less defined the Marshall sound back in the day.

I have a 50w solid state Marshall which hasn't worked for years. I was thinking I could maybe reuse some of the electronics as well as the housing and chassis and build a decent tube version for less than a fortune. ...And kind of recycle at the same time. I just got this brainstorm today, so just beginning my research.

---

Also beware. Old school Marshall’s sound best when really working hard which is REALLY FRIGGING LOUD. Unless you play arenas or have very understanding neighbors or do not value your hearing you may want to look at one of the 18W Marshalls. Even those will be REALLY FRIGGING LOUD but at least you’ll be able to gig with it at some places with the amp in it’s happy spot.

Even my little 5w champ will surprise you at how loud it gets.

That is true. I remember how loud my SS Marshall was. I have wished since that I had a 30w tube instead of a 50. You have a very good point. The 50w Plexi sounds wonderful on the app, but I can play it at bedroom volumes. I expect 18w is plenty for just about any venue I'd be looking at.

I'd probably not use one these days unless I had the speaker in an ISO cab with a couple pf good mics.

But, the reality is that building an amp probably won't save you any money. When we were kids we would take old tube radios or HiFi amps and convert them into guitar amps. Now, that saved money, lol.

It was also common practice to "borrow" the old Bogens from school and make a PA.

Chuck

Suggestion to the OP, figure out which Marshall sound you want. An 18w sounds different than a JTM45 or a Plexi of a 800 or a 900.

If you want the Plexi sound, do not go 18 watt. Different tone. If you want the Plexi tone at a lower volume, the Plexi 20 config is the one to look at. 18watts sound close to a JTM 45 than a Plexi.

Also a good point BonB. I haven't played a lot of Marshalls. Only the Jamup pro app. and my SS 50w. My fav, by far, on the app is the Plexi 50. I also saw a RobRob mod which reduces the power. I wonder if that would help. I'm not sure what it is exactly that I want, so I'm all over the board right now, but I'll eventually hone it down a bit. That's why I'm on this forum, and I do value all the input. So, thanks to all.

The Fractal is a good alternative too. That would be my suggestion. That way you get the cranked Marshall experience at a volume you can actually use in modern live setting.

Quote:

---

Originally Posted by Offshore Angler

The Fractal is a good alternative too. That would be my suggestion. That way you get the cranked Marshall experience at a volume you can actually use in modern live setting.

---

Now I wasn’t going to bring that up, but it is the solution. All the different flavors of Marshall at what ever volume you like. You can even change aspects with the amp models that allow to say recreate a Blackflag. Ive been Fractal for 15 some odd years.

I’ve also been working with a Helix LT recently and it’s not bad at all. It’s the house gear at a couple of venues I play at. So I picked up one for my music room, created some patches I desired and loaded the patches on the venues units.

Quote:

---

Originally Posted by blackonblack

Now I wasn’t going to bring that up, but it is the solution. All the different flavors of Marshall at what ever volume you like. You can even change aspects with the amp models that allow to say recreate a Blackflag. Ive been Fractal for 15 some odd years.

I’ve also been working with a Helix LT recently and it’s not bad at all. It’s the house gear at a couple of venues I play at. So I picked up one for my music room, created some patches I desired and loaded the patches on the venues units.

---

Yeah, most people don't understand that these days the amps onstage at a concert usually window dressing or stage props. Sure, to play a local watering hole I'll use the DR, but I have a dedicated sound man who mics it and feeds the mains and I trust him to make it sound good. But any time the gig is on a large outdoor stage the rack is coming out. It's sooooo much better to direct out and use the power of the FOH than try to blast through with your speakers farting out. Plus, I use a pair of Headrush 2000W FRFR cabs onstage for fill, allowing me to get the stereo mix of the delay and chorus. Since I'm DI the sound guy puts me in the other band member's monitor mixes as they like.

Tube amps are fun, but the reality of today is you generally sound better at modern volumes with a high-end processor.

When I look back at the early days - wired mics and guitars , snakes, light controllers with cans, a full pedal board and multiple amps - I just laugh and wonder how we were able to make it work. But we did. A modern stage is so much cleaner and easier to play on. LED lighting has made it a pleasure. In the old days of cans we would be covered in sweat at the end of the night, then had to go out into the dark cold snowy night to load out, freezing our tush's off.

Chuck

Quote:

---

Originally Posted by Offshore Angler

Yeah, most people don't understand that these days the amps onstage at a concert usually window dressing or stage props. Sure, to play a local watering hole I'll use the DR, but I have a dedicated sound man who mics it and feeds the mains and I trust him to make it sound good. But any time the gig is on a large outdoor stage the rack is coming out. It's sooooo much better to direct out and use the power of the FOH than try to blast through with your speakers farting out. Plus, I use a pair of Headrush 2000W FRFR cabs onstage for fill, allowing me to get the stereo mix of the delay and chorus. Since I'm DI the sound guy puts me in the other band member's monitor mixes as they like.

Tube amps are fun, but the reality of today is you generally sound better at modern volumes with a high-end processor.

When I look back at the early days - wired mics and guitars , snakes, light controllers with cans, a full pedal board and multiple amps - I just laugh and wonder how we were able to make it work. But we did. A modern stage is so much cleaner and easier to play on. LED lighting has made it a pleasure. In the old days of cans we would be covered in sweat at the end of the night, then had to go out into the dark cold snowy night to load out, freezing our tush's off.

Chuck

---

You are preaching to the choir LOL.

If I don't have FOH, I have some 1600W Mackie FRFRs that can handle it. Use to have QSCs, but those were 75 lb each. The mackies together are maybe 70 lbs. As I get older, I get wiser (maybe thats lazier). Less is more now.
I prefer IEMs to onstage monitors. A suggestion to anyone thinking of going IEM - Take your budget and x5 - then add a few hundred. My primary IEM set was 2K+. Believe me, its worth it!

Most my venues are representing sound non-panned, so I don;t ever worry about stereo effects. Its not making it to the FOH. I rely on the sound guy. I have already auditioned my tone and heard from the room what it sounds like (great use for a looper). Its their role and I need to trust them. They are trusting me to play and perform, so it is natural to trust them. Its all about building relationships.

The only amp I have now is a Boss Acoustic Singer Pro in the music room. I do happen across acoustic events where there is no FOH. Also subs as a vocal amp and has some vocal effects.
The main gear is the Fractal, Helix LT, an acoustic fly rig I put together and a bass fly rig. The bass fly rig will be going up for sale as I can cover it with the Helix LT as a fly rig.

I will admit, I still like tube amps, but the feasability of them has diminished.

Quote:

---

Originally Posted by blackonblack

I will admit, I still like tube amps, but the feasability of them has diminished.

---

I love small amps. Light and sound good at non ear splitting volumes. Even at home, I can get the tubes working to the point where I have a nice rich clean sound that makes pedals actually sound good and not buzzy. And when the family isn’t there? I can crank it and keep my neighbors happy and not have my ears bleed. I couldn’t imagine having more amp at home; I think a good digital modeling amp/fractal/HX would be better than a bigger amp at home TBH.

Totally don’t know what would work for me in a gig situation. I’d love to get there some day.

Quote:

---

Originally Posted by tugboat

I love small amps. Light and sound good at non ear splitting volumes. Even at home, I can get the tubes working to the point where I have a nice rich clean sound that makes pedals actually sound good and not buzzy. And when the family isn’t there? I can crank it and keep my neighbors happy and not have my ears bleed. I couldn’t imagine having more amp at home; I think a good digital modeling amp/fractal/HX would be better than a bigger amp at home TBH.

Totally don’t know what would work for me in a gig situation. I’d love to get there some day.

---

All totally possible with a Fractal or Helix. Plus you get to ditch your pedals.
My main patch is an AC30 on the edge of breakup. 2 OD items. 2 ABY delays that are split off/ chorus and verb are a third line. I pull them altogether right before output.

I can get the tone at either 60db or 130 db. (Even set up an exp pedal to handle tone changes for Fletcher Munson impact)

Quote:

---

Originally Posted by blackonblack

All totally possible with a Fractal or Helix. Plus you get to ditch your pedals.
My main patch is an AC30 on the edge of breakup. 2 OD items. 2 ABY delays that are split off/ chorus and verb are a third line. I pull them altogether right before output.

I can get the tone at either 60db or 130 db. (Even set up an exp pedal to handle tone changes for Fletcher Munson impact)

---

Not so on the pedals…you still have to pick and choose pedals and arrange a “pedalboard” in the digital world. Just because there’s no physical pedals doesn’t mean it eliminates futzing and setting up. If anything it might waste time because you’d spend playing time futzing with options you’d never have in the real world.

How do Fractals and such change with picking dynamics? My only comparison to anything digital is GarageBand and it just doesn’t react the same way to changes in picking and technique dynamics as a tube amp. There is also always a small delay between when you pick and when you hear the sound.

Quote:

---

Originally Posted by tugboat

Not so on the pedals…you still have to pick and choose pedals and arrange a “pedalboard” in the digital world. Just because there’s no physical pedals doesn’t mean it eliminates futzing and setting up. If anything it might waste time because you’d spend playing time futzing with options you’d never have in the real world.

How do Fractals and such change with picking dynamics? My only comparison to anything digital is GarageBand and it just doesn’t react the same way to changes in picking and technique dynamics as a tube amp. There is also always a small delay between when you pick and when you hear the sound.

---

Tug, it's actually more tactile with a Fractal, since you can fine-tune things like the cab response. Take an overdrive or distortion. They, by nature, add a lot of compression to your signal and remove the "feel" of the amp anyway. The object of them is to simulate an overdriven amp or one with cascading gain stages. They emulate that sound but add in the compression that robs the feel.

Now, with a high-end modeling system you get the opposite effect. Instead of adding lots of pedals you don't need, you set up different amps, all set to the overdrive you want, i.e., you already have the cranked Marshall or Dumble or Bassman from the get-go, so no pedals are needed. Sure add in a little delay for the leads and you're basically done.

The other thing that ADDS feel is layering amps, in that you can split your chain and run say, a Bassman and an AC30 at the same time. That gives you the feel of the Bassman with the womp of the AC30 at the same time.

In other words, you can switch out your entire rig with the push of a button. Not sure about you, but for me that's pretty darned handy!

My experience is the only place a tube amp will really shine is in a fairly large sized club with up around 100 people in it absorbing the sound. You can throttle up the power section of the amp and let it do its thing. And you have it mic'ed anyway so what the front is hearing is coming off the board and will be effected by the sound person, so you won't even be running reverb or delay in that case.

Smaller venues, take the fractal or PODHD Pro over it any day. I can rip singing leads with feedback and sustain and not be pissing off the bartenders. Large clubs and outdoors - well - rather than relying on my amp it's WAY, WAY, Way more fun to have thousands of Watts at your disposal and a really good monitor mix than some tube combo stashed in the backline. And since I have the stage power now, I don't need to use ears to hear myself.

Even in a small club I'll use a 2000W monitor as a stage fill. That way I get all the "Huge" at a low volume, but the bottom end is all there. This is where they really shine, because you can get that closed-back thump we all adore but at a volume that works anywhere. And, since no mic is required I don't get bleedover or footsteps on the stage coming through so it maintains much better separation of the instruments making the mix cleaner and allowing my guitar to cut said mix better.

Slightly overdriven Fender sound? Fuggetaboutit, the Fractal or PODHD Pro sounds and feels better than my DR. Guys in the band always smile when I hit my DR patch. It's sublime.

Downside is it takes up a lot of space, and it requires cabling to the main and monitor boards so setting it up is a lot more work.

My DR still gets played a lot, mostly because I have it and it's grab and go and it lives next to the door. I've played a DR for so long now I pretty much can make it work anywhere, and we have our own on-staff sound person who knows how I like it in the mix. But yeah, often times it's way too much amp for the venue. Like last Saturday for example.

But here's the thing with small tube amps - they sound small. The magic of most tune amps isn't in the tubes, it's in the magnetics. You'll never get one to sound big without mic'ing it and putting it into the house since they have tiny transformers and speaker magnets.

This is where the modelers shine, low volumes where you still want a wide, full sound, or in the studio.

In the studio its' a total no-brainer to use the modeler. I put my dry signal into the board, loop it out to the Fractal and then back in. I take the Fractal output into another channel and leave the control room slider down on the dry signal.

Now, On playback if we go,"Gee that would sound better with a Dumble" all I need to do is hit a button and it's re-amped with a different sound, or - tada!, I can spit it again and add another amp simultaneously to add a layered feel. Or hit a harmony patch on that extra amp. Or do a wet/dry mix and on and on.

In other words, when you go to high-end modeling you can sound so much better because the options are almost endless.

A few weeks back I needed to cover a Coral Sitar sound for some classic Motown, rather than scouring the earth for priceless gear and having to do onstage gear switching, I hit one button on my controller and Voila!, there it was.

Say you're in a cover band and you look at that night's setlist and you see Sweet Home Alabama right next to Cheap Sunglasses. Whaddya going to do? Change out all of your gear? Play them both through a Deluxe with pedals? How about better yet, hit a single button and go from an overdriven Fender sound to a balls-out Mesa Boogie?

And then, from the value proposition there's really no choice to be made. For under $4K you can set up an entry level rack, about the same price as a as a decent amp or guitar, but instead of one amp, you have them all. And the ones they sample for the models are shining examples of the type, not just the one you could find.

I mean yeah, I get it. Tube amps are like muscle cars. We all love 'em, they look pretty and sound great. But in the modern world a Ford Focus will blow the doors off of a 70's muscle car. So do you want to look cool and relive your youth, (nuthin' wrong with that) or do you want the best performance, ride and handling?

Chuck

I’m not dissing modelers. Much of my playing time is spent with GarageBand. It’s cool, partially for the reason you mentioned with switching instantaneously. Today at work during lunchtime guitar practice I split time between the BF Fender and AC-30 presets. Very cool. But. I still feel a difference when playing through GarageBand vs an old school amp and I prefer the old school amp. Even an amp with pedals. The latency just takes away from the experience, and it’s the latency I’m specifically talking about. Also, I don’t hear a “big amp” difference with a modeler in my context. Live? No idea…I’ll trust your assessment since you have been around the block many times and I’m still on the back porch. But in my house? I prefer my Champ and some pedals over GarageBand every time. Even better…my champ turned up. I doubt headphone practice or tv volume speaker practice with a modeler will give one the big iron experience you suggested, other than switching on the fly.

I would have to assume a Fractal has much lower latency than an iRig through an iPhone, but a Fractal is way more money than I’m willing to spend on a digital amp. If I were to invest that kind of money into something it better be around for a long time and I am suspicious anything digital will be anything but outdated and incompatible with of the time technology 10 years from now. I’m sure you make much better use of yours as you are a professional musician, and I can totally see how it can be helpful in the studio. It’s gonna be on “tape” anyways so what does it matter if it sounds good? And who’s gonna schlep a Super Reverb, AC-30, Marshall Plexi, a HiWatt, a Tweed Bassman, and whatever else to a recording session just in case you need one of those?

But I gotta ask…what’s wrong with playing Cheap Sunglasses and Sweet Home Alabama through the same amp?

Quote:

---

Originally Posted by tugboat

But I gotta ask…what’s wrong with playing Cheap Sunglasses and Sweet Home Alabama through the same amp?

---

I managed such a feat for decades and it didn't seem to matter whether it was a Deluxe Reverb, a Vibroverb, or a Twin Reverb, either to my bandmates or -- more importantly -- to the audience. So long as you rock the house it doesn't matter.

Quote:

---

Originally Posted by phantomman

I managed such a feat for decades and it didn't seem to matter whether it was a Deluxe Reverb, a Vibroverb, or a Twin Reverb, either to my bandmates or -- more importantly -- to the audience. So long as you rock the house it doesn't matter.

---

My experience as an audience member is that it’s all in the sell. Gear doesn’t even have to really be in the ballpark. Brad Paisley plays Hot for Teacher with a Telecaster and a Dr. Z AC style amp? Nowhere even in the “tonal ballpark” of a Flying V into a dimed Marshall but it sounded pretty cool to me. He played it well and with conviction, audience loved it.

So Tug, I noticed you brought up latency in GarageBand. First while the GB sounds terrible, it's also not a processor. There is no discernable latency in a processor, no more than a tube amp. GB is an emulation in an already bloated application.

It sounds like maybe you've made you mind up you like the tube amp better than the processor before even trying one? I'm just saying - be open minded an realize that for live performance tubes are falling by the wayside very quickly. The days of cranked amps in the local watering hole are long past.


What I often run into is that people have tried the old floor units from the old days which did basically sound like crap and then pigeonhole all processors into that box without ever trying modern, pro-level gear.

As far as holding up, Fractals have proven to be road warriors. My rack got dropped down the stairs this year and the only thing that got hurt was the road case. Can't say the same about my tube amps. They don't like life on on the road for sure.

I mean yeah, I get it. There's always going to be those "tone" guys. Whatever. I've made my feelings known about that stuff many times. They're entitled to theirs too.

Quote:

---

Originally Posted by Offshore Angler

So Tug, I noticed you brought up latency in GarageBand. First while the GB sounds terrible, it's also not a processor. There is no discernable latency in a processor, no more than a tube amp. GB is an emulation in an already bloated application.

It sounds like maybe you've made you mind up you like the tube amp better than the processor before even trying one? I'm just saying - be open minded an realize that for live performance tubes are falling by the wayside very quickly. The days of cranked amps in the local watering hole are long past.


What I often run into is that people have tried the old floor units from the old days which did basically sound like crap and then pigeonhole all processors into that box without ever trying modern, pro-level gear.

As far as holding up, Fractals have proven to be road warriors. My rack got dropped down the stairs this year and the only thing that got hurt was the road case. Can't say the same about my tube amps. They don't like life on on the road for sure.

I mean yeah, I get it. There's always going to be those "tone" guys. Whatever. I've made my feelings known about that stuff many times. They're entitled to theirs too.

---

I haven’t made up my mind on that (I made it a point to state that I’d assume a Fractal would be a different beast than the GarageBand and an irig that I use at work), it’s just that from what I’ve seen thus far good processors like Fractals are very expensive, especially for something like that that will have a shelf life, and seem to take some skill to dial in correctly (or invest yet more money in presets someone is selling) and being someone who doesn’t gig and just plays at home and whose amp is perfectly fine for my uses I have no need to invest in one. If I did gig, sure it would probably be worth it to spend a couple grand on one. It would solve the “my amp is too loud/too quiet” complaints for sure. If I lived in an apartment or a condo…that changes the calculus as well since tube amps are too loud and sound like shit in apartment friendly volumes; I’d probably buy one if I lived in an apartment or a condo.


But I don’t believe tubes will go anywhere. Will they dominate like they did for decades? Maybe, maybe not. Look at watches. The only companies making meaningful money in watches are either Apple or companies who make old school spring powered hand or automatic winding watches using centuries old technology. There is no universe where a Rolex is a better timekeeper than an Apple Watch or even a $75 Casio, but I assure you more money is made at Rolex than Casio. The market will be diversified, but tubes aren’t going anywhere.

Quote:

---

Originally Posted by tugboat

The market will be diversified, but tubes aren’t going anywhere.

---

Neither is my Rolex......

https://i.ibb.co/FxmsrNk/Rolex-ZZsm.jpg

GarageBand or iRig is as different from a Fractal, Kemper, Helix as night is from day. The are not apps or plugins used on a device not designed for music (computer).
They are specifically designed to do one thing, music. Latenancy is non existent. I know, been using them since 2008 or 9.

Yes, they are not cheap, but neither is a good tube amp. Nor all the stomp boxes to go along with it. Let's say you need to do the U2 thing (which I do), minimum you need is 1 OD and 2 delays. Well the OD isn't that much, but price out buying to Strymons for the delays.

If you start to consider a modeler, here's how I would look at the top 3.

Fractal - top of the line
Kemper - some prefer it over Fractal, not I. About same price point.
Helix LT - the sleeper in the group. The Line6 stuff with the HD/Pod units was so so. The Helix products are quite better with the LT being the sleeper. I acquired a used one in mint condition recently for $700. A venue I play at has the as house units, so I got one to work on. Well that venue now uses my patches (guitar and bass).

I am not trying to tell you to ditch tube amps. What I am saying is don't compare a modeler to a computer plug in. They are as different as night and day.

Quote:

---

Originally Posted by blackonblack

GarageBand or iRig is as different from a Fractal, Kemper, Helix as night is from day. The are not apps or plugins used on a device not designed for music (computer).
They are specifically designed to do one thing, music. Latenancy is non existent. I know, been using them since 2008 or 9.

Yes, they are not cheap, but neither is a good tube amp. Nor all the stomp boxes to go along with it. Let's say you need to do the U2 thing (which I do), minimum you need is 1 OD and 2 delays. Well the OD isn't that much, but price out buying to Strymons for the delays.

If you start to consider a modeler, here's how I would look at the top 3.

Fractal - top of the line
Kemper - some prefer it over Fractal, not I. About same price point.
Helix LT - the sleeper in the group. The Line6 stuff with the HD/Pod units was so so. The Helix products are quite better with the LT being the sleeper. I acquired a used one in mint condition recently for $700. A venue I play at has the as house units, so I got one to work on. Well that venue now uses my patches (guitar and bass).

I am not trying to tell you to ditch tube amps. What I am saying is don't compare a modeler to a computer plug in. They are as different as night and day.

---

Bingo - A nice amp is going to cost between 2 and 3 thousand dollars, and then you spend thousands on pedals. And - the signal chain gets losses every pedal you add.

So like I said, form a value standpoint you can't beat the modeler. It's much, much cheaper and you get balanced outputs. No brainer if you play live.

Just buy a used DSL 40 and be done with it. Killer tone for about $600. Reverb too!

Quote:

---

Originally Posted by Tele-Bob

Just buy a used DSL 40 and be done with it. Killer tone for about $600. Reverb too!

---

I've used them in supplied backlines, they're pretty crisp but fun if you know how to dial in the guitar's tone controls. Pretty stout for home use though.
I'd say just get a Tiny Terror or even a Micro Terror and a 12" closed back and wail away for the bedroom.