50w Plexi mods

Swapping out speakers in cab -OR- putting a hammer though your Line6 Spider? Tell us about it.
Post Reply
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Minerman wrote: Thu May 11, 2017 6:35 pm Pretty cool Greg....Not sure I'd even attempt anything like that, my soldering skills are ok, but my hands aren't as steady as they once were, to put it mildly...


That's some nice, clean looking work dude... :minernuggs:
Thanks miner. I'm thinking you would really like the sound of this amp now. :metal:

It's got shitloads of hairy gain but still has that bonk and clarity that you'd want from a Marshall. And best of it all for me, it still works as a stock 50w Plexi. The hair gain feature is just nice to have. :punk:
Rebel Yell
User avatar
Minerman
Posts: 2022
Joined: Wed Jan 04, 2017 3:51 pm
Location: U.S.A.
Contact:

Re: 50w Plexi mods

Post by Minerman »

Greg_L wrote: Thu May 11, 2017 9:26 pm
Thanks miner. I'm thinking you would really like the sound of this amp now. :metal:

It's got shitloads of hairy gain but still has that bonk and clarity that you'd want from a Marshall. And best of it all for me, it still works as a stock 50w Plexi. The hair gain feature is just nice to have. :punk:
Just callin' it like I see it, & that is some pretty neat/tidy work...

Yeah man, to me the hot-rodded plexi is the holy grail of guitar tone...There just have been so many songs/albums that I like that have one version or another of that tone...It's hard to describe for me, but the "bonk" & "kerrang" of those amps are just magical IMO...

Post us some sound clips if/when you get time dude, I'd love to hear what it sounds like now...

BTW, is that the amp you used when we were trying to find out if the Chupa was in the plexi ballpark??? It seems like it to me, but I just can't remember...
Image
Gibson, Fender, Ibanez, Jackson
Ceriatone, Marshall, EVH
TC Electronic, MXR, Yamaha

My music @ Reverbnation :minernuggs:
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Minerman wrote: Thu May 11, 2017 10:29 pm

BTW, is that the amp you used when we were trying to find out if the Chupa was in the plexi ballpark??? It seems like it to me, but I just can't remember...
No, that was the 100 watt. I don't think I had this amp when we were doing that stuff. Your Chupa had tons more gain than a regular Plexi.

This is a 50w reissue I picked up a few years ago for 600 bucks! It was like brand new, sitting in some guy's closet. Too loud for him is just right for me. A $2500 dollar amp, I got it for 600. It's cool because it's one of the early reissues and that means no effects loop. It's just pure raw Plexi circuit.

I'm seriously thinking of building something now, or converting this thing to a turret board instead of PCB. Amps with turret boards are so much easier to deal with. I think a Plexi with tremolo and spring reverb would be bad ass.
Rebel Yell
User avatar
rayc
Posts: 8452
Joined: Wed Jan 04, 2017 6:31 pm
Location: South of Bundaberg North of Brisbane

Re: 50w Plexi mods

Post by rayc »

VERY tidy Greg, I'd like to see how you store your shoes.
Cheers
rayc
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

rayc wrote: Fri May 12, 2017 12:40 am VERY tidy Greg, I'd like to see how you store your shoes.
Thanks Ray. My shoes stay wherever I kick them off. At any given time, in any given room, I have a shoe, maybe both, in there somewhere.
Rebel Yell
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Man this thing sounded awesome tonight. Good job Greg! :punk: :like: :nyuk:

I think I might want to do some tweaks to the coupling caps to tighten the bass a little, but I'm gonna let it ride for a bit.
Rebel Yell
User avatar
Minerman
Posts: 2022
Joined: Wed Jan 04, 2017 3:51 pm
Location: U.S.A.
Contact:

Re: 50w Plexi mods

Post by Minerman »

Greg_L wrote: Thu May 11, 2017 11:37 pmNo, that was the 100 watt. I don't think I had this amp when we were doing that stuff. Your Chupa had tons more gain than a regular Plexi.
Yeah, I remember now, we both used a LP, G12 T-75 speaker & an SM57 mic with the knobs on both amps on "5"...I may even have the clips we posted, I'd have to dig around on an external hdd, but I think I've still got those...I've got a bunch of your clips from HR that I use for a reference/baseline to dial in different tones sometimes... :biggrin:

I think that the gain was the only thing we couldn't get the same, I had both bright switches centered/off, & the era switch on "Plexi', but I still had to guess on how much gain to use by listening to your clip...

That was a lot of fun for me dude, the Tone Thread was in full swing!!!
I miss those days man, my personal life was a fuckin' trainwreck at the time, but the thread & everybody involved helped get me through... :minernuggs:
Greg_L wrote: Thu May 11, 2017 11:37 pmThis is a 50w reissue I picked up a few years ago for 600 bucks! It was like brand new, sitting in some guy's closet. Too loud for him is just right for me. A $2500 dollar amp, I got it for 600. It's cool because it's one of the early reissues and that means no effects loop. It's just pure raw Plexi circuit.

I'm seriously thinking of building something now, or converting this thing to a turret board instead of PCB. Amps with turret boards are so much easier to deal with. I think a Plexi with tremolo and spring reverb would be bad ass.
I remember when you found an amp for $600, but couldn't remember which one...

I say go for it man, I'm sure you'd do a fine job...The only suggestion I'd make is for you to build something different...I mean for fuck's sake man, you've pretty much got every Marshall tone that can be had...
I'd suggest you build some version of a Fender, but I'm sure if you do build an amp, it'd be great... :minernuggs:
Image
Gibson, Fender, Ibanez, Jackson
Ceriatone, Marshall, EVH
TC Electronic, MXR, Yamaha

My music @ Reverbnation :minernuggs:
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Minerman wrote: Sat May 13, 2017 7:05 am
I'd suggest you build some version of a Fender, but I'm sure if you do build an amp, it'd be great... :minernuggs:
That's what I'm thinking. A Fender Super Reverb or Deluxe Reverb. I've been looking at the schematics and they're both probably way over my head but fuck it. No guts no glory.
Rebel Yell
User avatar
Minerman
Posts: 2022
Joined: Wed Jan 04, 2017 3:51 pm
Location: U.S.A.
Contact:

Re: 50w Plexi mods

Post by Minerman »

Greg_L wrote: Sat May 13, 2017 10:29 am That's what I'm thinking. A Fender Super Reverb or Deluxe Reverb. I've been looking at the schematics and they're both probably way over my head but fuck it. No guts no glory.
I'm sure you'll do fine dude...
Image
Gibson, Fender, Ibanez, Jackson
Ceriatone, Marshall, EVH
TC Electronic, MXR, Yamaha

My music @ Reverbnation :minernuggs:
User avatar
Lt. Bob
Posts: 6558
Joined: Wed Jan 04, 2017 3:02 pm

Re: 50w Plexi mods

Post by Lt. Bob »

Greg_L wrote: Sat May 13, 2017 10:29 am
Minerman wrote: Sat May 13, 2017 7:05 am
I'd suggest you build some version of a Fender, but I'm sure if you do build an amp, it'd be great... :minernuggs:
That's what I'm thinking. A Fender Super Reverb or Deluxe Reverb. I've been looking at the schematics and they're both probably way over my head but fuck it. No guts no glory.
I love Supers .... be aware they're set up to run into 2 ohms.
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Minerman wrote: Sat May 13, 2017 10:57 am

I'm sure you'll do fine dude...
Shit, looking at Blackface reverb/tremolo kits....I might as well just buy a real one.
Rebel Yell
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Lt. Bob wrote: Sat May 13, 2017 12:13 pm
I love Supers .... be aware they're set up to run into 2 ohms.
In kit form I might be able to use an output tranny that can do whatever I want.

Whatever I build will be a head. No combos for me.
Rebel Yell
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

I think instead of a total amp build I'm gonna make and swap a PTP board into this amp. I already hav the chassis, head cab, and all the shit that goes along with it. Maybe I can populate a turret board with all the right caps and resistors and wire it in place of the PCB!
Rebel Yell
User avatar
Tadpui
Posts: 3358
Joined: Thu Jan 05, 2017 3:50 pm

Re: 50w Plexi mods

Post by Tadpui »

Very ambitious! What a great opportunity, to have a great yet inexpensive amp to play with. This has given me the hankering to do some soldering, but I think that for now I'll stick to Velleman and Elenco DIY kits. I'll have to work my way up to potentially ruining a good amp :D
User avatar
WhiskeyJack
Site Admin
Posts: 11366
Joined: Sun Jan 12, 2014 11:48 pm
Location: Canada
Contact:

Re: 50w Plexi mods

Post by WhiskeyJack »

becasue i am lazy and don't have time to dig, have we had tone samples of this yet?
:happytrees:
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

Tadpui wrote: Tue May 16, 2017 2:03 pm Very ambitious! What a great opportunity, to have a great yet inexpensive amp to play with. This has given me the hankering to do some soldering, but I think that for now I'll stick to Velleman and Elenco DIY kits. I'll have to work my way up to potentially ruining a good amp :D
Unless I'm totally misunderstanding things...it looks like I can convert this Plexi reissue into a Metro PTP for about 100 bucks. That's pretty interesting. If I want to upgrade the transformers that'll be a few hundred more.

Metros are probably the best clones out there. And a PTP is way easier to work with. I can make this thing whatever I want. I *think* my stock transformers, choke, and filter caps can all stay as-is. All the switches and tube sockets and pots and shit can stay the same. Chassis and head box the same. I'll need to figure out how my rectifier circuit correlates with the PTP version, and if my filter caps can stay the same, but other than that I think it's just a matter of making the PTP board and wiring it into the chassis.
WhiskeyJack wrote: Tue May 16, 2017 2:08 pm becasue i am lazy and don't have time to dig, have we had tone samples of this yet?
Not yet. I still need to do a couple things, but they're coming soon. I'd say it's about 90% good right now.
Rebel Yell
User avatar
rayc
Posts: 8452
Joined: Wed Jan 04, 2017 6:31 pm
Location: South of Bundaberg North of Brisbane

Re: 50w Plexi mods

Post by rayc »

Sounds like you contracted tinkeritis Greg.
I can't get my head around 90% of what you're doing so I'll sit back and follow as usual.
Cheers
rayc
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

rayc wrote: Tue May 16, 2017 7:09 pm Sounds like you contracted tinkeritis Greg.
I can't get my head around 90% of what you're doing so I'll sit back and follow as usual.
Ha I don't know what I'm doing either.

I'm still not sold on this cascade mod. The PPIMV is great. The gain mod....it sounds good but I still think it just sounds better as stock and slamming it with a tube screamer. The gain mod seems like it's just too much....gain. Lol. I can dime everything on this amp in stock form and all hell breaks loose. But with the gain engaged it's just too compressed and it gets harsh. I don't think I wanna start tone-shaping this thing with cathode resistors and bypass caps when it really does just sound better stock with a Tube Screamer. :crazy: :cuckoo:

Soooooo....I'll still do clips, but I think I'm gonna stop and shift my focus to making a PTP board for this thing.
Rebel Yell
User avatar
rayc
Posts: 8452
Joined: Wed Jan 04, 2017 6:31 pm
Location: South of Bundaberg North of Brisbane

Re: 50w Plexi mods

Post by rayc »

Yeah, the amp is a classic for a reason ans the simplicity of an OD hitting hard from the front is hard to beat.
I couldn't see you using the modded high gain tone for anything - it is, essentially, anathema to your sonic principles.
I'm going to experiment with tube preamps in front of my Marshall this week. I have a couple of pres that have a tube in the path for "colour", (a Behri Mic100 & a Presonus BlueTube), as well as in front of my little 5 watt Kustom.
I'll probably post a few samples as I REALLY can't tell what's good & what's not.
Today I have to take my motorcycle to the workshop for new fork sleeves, (fork seals have been ruptured by rust in the chrome AGAIN), and new handle bars. The workplace parking, uncovered & outside all day for 9 years and a just 1Km from the Tasman Sea certainly does damage to cheap Thai chrome work.
Cheers
rayc
User avatar
Greg_L
Posts: 20629
Joined: Wed Jan 04, 2017 1:07 pm
Location: Where the knuckle meets the poophole

Re: 50w Plexi mods

Post by Greg_L »

rayc wrote: Tue May 16, 2017 9:46 pm Yeah, the amp is a classic for a reason ans the simplicity of an OD hitting hard from the front is hard to beat.
I couldn't see you using the modded high gain tone for anything - it is, essentially, anathema to your sonic principles.
I'm going to experiment with tube preamps in front of my Marshall this week. I have a couple of pres that have a tube in the path for "colour", (a Behri Mic100 & a Presonus BlueTube), as well as in front of my little 5 watt Kustom.
I'll probably post a few samples as I REALLY can't tell what's good & what's not.
Today I have to take my motorcycle to the workshop for new fork sleeves, (fork seals have been ruptured by rust in the chrome AGAIN), and new handle bars. The workplace parking, uncovered & outside all day for 9 years and a just 1Km from the Tasman Sea certainly does damage to cheap Thai chrome work.
Again, you REALLY should mod that Superbass to Super Lead spec. That thing will be holy fucking awesome! :coolstorybro: :coolstorybro:

I'm starting to second guess the cascade mod. I just like it so much better in it's stock regular Plexi form. When I build the PTP board I'll probably just put it back to stock. On the plus side, the push/pull cascade mod has no effect on the normal functionality if I wanna use it in stock form.

I did another slight mod today. This amp has a 70s "metalface" era negative feedback loop. Which means it's pretty "loose". Real 60s Plexis had way tighter power sections and more negative feedback. Negative feedback is a feature in many tube amps where a piece of the output signal gets siphoned off, reduced, and rerouted back through the power section to cancel out any oscillation or weirdness. This results in slightly lower distortion in the power section, but a more balanced and tighter sound. Mostly low end is tightened up a lot. The presence control on many amps is tied in with the negative feedback loop. Presence is kind of weird in that it filters out high end to let more low end through the negative feedback loop. This additional low end in the negative feedback actually cancels itself out therefore leaving more high end. Weirdo! Anyway, my amp has a 100k resistor in the neg feedback circuit going to the 8 ohm speaker tap. I simply moved the negative feedback wire to the 16 ohm tap, effectively reducing that resistor by about a third. Bam, more negative feedback, tighter low end. Low end has never been a problem with this particular amp, so I think it really helped a lot. It's much tighter in the low end and punchier. That's a good thing. So that happened.
Rebel Yell
Post Reply