'76 Marshall JMP rescue and S.I.R. #36 style mods!!

[@rowenthomson2351]

"shield everything" is even more important in the small chassis models, where an extra stage is a tight squeeze. Even a 1 inch unshielded grid wire will oscillate! Great idea adding the cap on the gain pot, I was using a bypass cap on the cathode follower to achieve similar results!

[@ScottyBrockway]

The debauchery I see from so called amp techs never ceases to blow my mind. Good work bringing it back to usable state.

[@GTguitarworks]

Beautiful work Jason, you never stop amazing me with how good your MODs are plus Your soldering, wiring and how you make the inside of these amps look like a work of art! On top of all that you're willing to share it with us... Can't thank you enough because there are thousands of Marshalls out there, needing this kind of Proper love.. and guys like us that grew up when the amps were new.. It brings back all the memories... I Love your Channel man... can't say enough...

[@HeadfirstAmps]

Hey Guy, thanks man I appreciate your kind works. I really do. Plenty more Marshall’s need to be rescued!

[@johnmarshall3903]

These vintage Marshall restorations and well done amp mods are fantastic. Thanks to you again for sharing your knowledge with us. Damn good playing too!

[@HeadfirstAmps]

Thank you John!

[@jayguitar]

Awesome! I love my SIR#39/36/34 conversion Jet City. It’s a beast and there’s something very special about that tone and mid range 😊 fantastic tones Jason 🤟🤟🤟

[@phillamoore157]

You got a demo up of that amp, Jay?

[@jayguitar]

@@phillamoore157 hi Phil, yes I do. I have the full build videos on there too. Here’s the playlist on my channel - kzbin.info/aero/PL_rPJ1xAg8UJwkw0TePkaFN6ov1NDv726 😊 it’s such a cool amp! Has this biting, mid-range tone which is lovely to play. I did a comparison between that and my custom SLO build to get the George Lynch Wicked Sensation tone a couple of weeks back which you can check out also, really shows the differences between the amps - kzbin.info/www/bejne/aJ2bnWOppL2fiMU - enjoy!

[@jayguitar]

@@phillamoore157 btw, it’s listed as building the ultimate Lynch amp in the playlist.

[@phillamoore157]

@@jayguitar Very cool...I'll check that out. Thank you.

[@justinchanjinle]

Thanks heaps Jason for restoring my JMP and modding a killer #36! I was totally unaware how much a mess it was! “If someone tells you the amp is stock, don’t believe them!” are definitely words to live by when buying vintage amps! Highly recommend Jason’s #36 mod for those of you who are after that tone. I’ve had the AFD100 and it didn’t come close to this at all. The AFD100 had a real bitey tone that sounded too much for me and just didn’t sound right to my ears. I’m so glad I brought this amp to Jason. It is now my #1 amp!

[@anthonydevito1298]

Watching this is like watching those feel-good videos where they find a sickly stray kitten covered in mud, and then clean it up and give it a good home with a loving family hahaha

[@primaballerina84]

You're a amp tech gem Sir! I hope you understand how good your content is! I'm a beginner tube amp tech/modder & builder and many of your videos have cleared things up for me like nothing else has! Thank you Sir for your work! Keep em coming! Peace from 🇸🇪

[@HeadfirstAmps]

I appreciate that!

[@mariannwatt2678]

I was told when my manager gave my 68 50w smallbox plxi marshall amp 40 years ago that it had been a sir amp at one time its bone stock and still like new BUT it still has a fan inside on the left side of the cabnet and a series of small holes thru the cabnet . the holes are hard to see . i was told that studio amps at that time often got fans for cooling due to long hours of use in sessions love my marshalls good show thanks for posting

[@alexcatlow]

Beautiful finish of the wiring job 👌 looks much better! great job!

[@SteveR5954]

Awesome. Some of the tones are very Live at the Ritz GNR.

[@HeadfirstAmps]

You made me go and watch that again 🤘

[@p_1210]

Awesome resto Jas sounds great! Man that amp was a mess.

[@HeadfirstAmps]

I got a hell of a surprise when I first flipped it over that’s for sure!

[@Valerio_VDF]

Nice! my jmp2204 is a stock/34/36 modded amp too... I really love it :) on the 36 gain stage I used a pushpull pot and I can activate/deactivate it and control the gain of this stage for more flavours :)

[@Guitarjosii]

Your work is so good, it makes me wish that I would live in Australia 😂

[@_patrikjay_]

"I don't even know where to start"... Hilarious! Love the playing parts but At The Bench is my jam.

[@HeadfirstAmps]

Haha, yep. Honest reaction! More bench stuff to come, I got a bunch of Marshalls here waiting for me to rip into them. Stay tuned!

[@richard66754]

Love the upper mid clank!

[@marvelharris9540]

another great job jason!

[@krlosgat]

Genial Maestro!

[@crflores76]

Very clean job… It was a disaster…👏👏👏

[@crflores76]

I love the rocker switch era (jmp 1976-1980)

[@scottpeters4401]

Hey Jason,I have never actually heard a 34 or 36 Modded amp in person,but I have an AxeFXIII,which has a 34 and AFD model …I was wondering if the ones in the Fractal were a close representation of what the mod really sounds like?….because if it is,I don’t like it,HaHa!!……it’s very thin and bright….but this one you have done,sounds way better to me…..I like this one a lot..

[@HeadfirstAmps]

Yeah the 34’s are really brittle. The 36 has the added 10k cold clipper stage which fattens it up. Also the depth circuit helps a lot.

[@stephenfrancis303]

Whats the diffrence between what you did sir style and jose 3 mod. Im looking to send you my 1987 . i had a splawn quick rod i liked the tone but it was too hard and cold not spongy and saggy enough i had a ceriatone sir amp from nik and it was too bright and biting. I had a hotrod 50 from soldano i love your work. I love youe channel

[@Mark70609]

One thing to remember is that humbuckers that aren’t potted will squeal, potted humbuckers are required for a high gain Marshall. Is there a switch to go between 34 and 36 modes? What did you do with the additional inputs, just disconnected them? Isn’t there a gain switch on these amps that puts a 0.1uF across the first 10K clipper and puts a 220K across the gain pot? Did you hardwire the extra gain in or omit it. I’m surprised there isn’t a version of this amp using two 6V6’s. It would still be loud but not deafening.

[@HeadfirstAmps]

Re the pickups, amp oscillation is not the same thing as pickup squeal.

[@mariannwatt2678]

I saw a video you did on the 100 marshall dsl . im in california (LA) i have a made in GB 2006 dsl do you know of someone in this area that i could talk to about mods . like the show fun stuff cheers j watt .

[@johnsimms3957]

I only 'mods' I like to do with my amps is to change the tubes and or put a pedal into the front of it.

[@armandodiaz67]

Question.... Do all shielded wires need to be grounded?

[@TheAxe4Ever]

DANG!! 😮

[@weschilton]

Man that amp was hacked! So you didn't mention... why were there four inputs on the front of the amp?

[@HeadfirstAmps]

It was a 1959SLP. Traditional 4 holer.

[@mikejozz6997]

I have a similar situation with a Marshall 2204 fx loop I'm going to replace with the Headfirst board. I don't want to drill more holes for the jacks so I need to mount it to the chassis. How is that attached? Just a single standoff right in the J1 Send box on the board?

[@HeadfirstAmps]

Same as how I mount the fx loop on the Origin20 video. If you use star washers it’s secure.

[@RozsaAmplificationLLC]

I always like to use bubble gum to fasten my HV boards to the chassis!! {rolls eyes} lol

[@HeadfirstAmps]

hahaha, yep!

[@OperationEndGame]

😂 that is totally frankenstein’ed mod