Amp Reassignment Surgery - 60s Lafayette PA Thinks it's a Marshall 2204
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- Опубликовано: 9 сен 2024
- ...and who are we to judge? In this video we will perform an elective guitar amp conversion surgery on a 1968 Lafayette PA645A. It thinks it's a JMP or JCM-800 2204.
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Forgot to mention... Marshall and Fender schematics used in this video came from the Tube Amp Book. I have an early edition, but the later editions are nicer. Good book to own for most common schematics: amzn.to/2DYyFv0
The original 50W fender amp schematic can be found in a 195x RCA tube reference guide . Ping me - I'll share a copy
Lafayette Electronics - a blast from the past!
Yes, Mr. Guitalogist you have created Marshall/Fender Monster Amp and your wife signed and confirmed it at 1am. in the morning. Great job love your video.
Nice Roadstar II and great video, as always.
Those era Ibanez guitars will always be worth every cent anybody paid for them.
It's about time Brad!!!! Re-purposing old PA and Hi-Fi amps for guitar is what originally brought me to your channel. I hope to see more in the future. Great work.
Thanks for sticking around!
Omg! I'm addicted to your videos bro! I'm truly grateful for your channel during this Covid-19 lockdown. I'm also seriously considering taking some electronic repair courses online at 52 years of age. You're never too old to learn something new....
To my ears, this amp sounds as good as any i've ever heard (for the type of tone amp i like to play through). Killer tone. Nice noodling to.. good pickin' and good finger tone.
Hey man! Just wanted to congratulate you on your channel! It is truly a very informative and super interesting channel to watch! I'm a guitar player myself and an electronic engineering minor, so I find your videos super cool, and can't stop watching them. I also love the way you go about "troubleshooting" these pieces of equipment, very logical, no non-sense and to the point, with some great electronic tips and tricks to go along with it! Thank you so much and keep doing what you do!
Wow Brad that PA turned out great! I usually just gut the entire pre-amp, and then copy an existing design of an amp I know I like. You took what was there and made changes until it sounded like you wanted, a much more daunting challenge. Bravo, well done Take care, Tom
The trial and error is the fun part.
You're fearless. I'm not talking about the amp, I'm talking about laughing at the awakened woman. 😎
Highway to the Danger Zone, my friend. It's the only place a Maverick like me lives.
that was comedy..thx
I love it when ppl scratch the arrows around the knobs so everyone will know where to set the knobs.
They'll all be wrong now. And I think it's just pencil.
Wow your final result is amazing! It sounded choked at the first stage but you really opened it up to breath. Nice!
Nothing says "skill" like this video.
Truly impressive when you can design a circuit that predicts tones when "improvising" like you were.
I only wish I could do some like that.
The interaction with the family solidifies my opinion of you as an individual.
Keep on doing what so few can do!
That thing sounds amazing! you did as such a fantastic job it's inspirational thanks for helping us all learn how to do these things
Awesome video Brad, I always love the long videos. I can sink my teeth into it, and enjoy the process. Cheers.
nice 1 a.m. repair! superb work!
It's the only time I can get away from the fam and have quiet time to think.
very nice ! A very succesful reassignment surgery Doc. you made the amp sound really good, and possibly solved the problem I have with my amp.
Man you pulled all the eggs out on this one my friend. Nice job Brad.
Thank you Carl. Good to see you.
Just about everything you touch comes up ROCKING!
I hear a lot of Leslie West in your playing this amp sounds amazing !!!!
Yes you nailed it again Brad, just awesome 👍
Ok... This video was awesome! Thanks for the detailed look at what you were doing and WHY. I'm not an amp repair dude, but I've got a list of stuff I want to try. This type of thing is def on my list.
Wow, what a beautiful, spotlessly clean chassis underneath; looks fresh from the factory floor! I love beautiful, clean design, especially on tube equipment!
Yeah, this thing obviously sat in one spot for a long time.
The best part for me was seeing your smile when you saw your daughter.
Super Vid..!! Great modifications to the Lafayette...kind of Sounds like my 1963 Bassman
Dig the 'Initech' mug...nice work on the amp too!!
That turned out great. What a versatile amp.
1 AM? You, Brad, are one hard working dude.
Big fan of your videos man. You always do great work.
I have redone 4 of these and they do rock the house, they make awesome rocking amps with minimal work , keep building, love been hooked for years
Awesome job Brad !!! Sounds Great !!
thanks,that is one heck of a do all amp mod,sound great here.!
I loved Lafayette stores and the equipment was really good. I grew up in Canada and they did not sell it there.
That aux fade is pretty cool, never seen that before
DAMN, that sounds good!!! I remember ordering Lafayette catalogs when i was a kid, pretty much when this amp was made.
Never seen anything in person since then. Freakin' lucky so and so who got this and found you to Fire It Up!!
I'll sell it to you.
The Bogen chb35a I've had about 15 years converted to guitar 🎸 amp, really sounds great with the 7868 tubes, really clean tone until about 6 or 7, I've been subscribed for years to your channel 👌👏👍, keep on rocking 🔊😀🎸
Thanks for keeping me entertained while I deal with the flu!
Nice work! It has a nice break-up. I like it a lot. I added a 12AX7 to a valve jr. Head and cloned a 2203 gain stages, cathode follower tone circuit, global NFB & presence. Wish I had room left on the panel for more options to incorporate the bassman sound. Thanks for the video man, I enjoyed it and as always I learned new information as well.
Where did you find that banner Brad ? That’s so cool, RCA all the way. If that doesn’t get a thumbs up nothing will. Great video Brad keep them coming.
Got that on eBay. I like it too. And it wasn't very much money.
Cool amp NOW. GREAT JOB like always, Alfred NYC/PR
Nice video. This gives a new meaning to the "la - Mar" conversion, and it's even a little bit Fendericky.
My father just built 3 of these and I'm currently testing an older model 645A and it's the dog's balls. Just a fantastic, organic, warm and round tone. Loves pedals. Running through an older 80's slant front 2x12 Marshall cab (from the Mosfet days) with 35 watt Celestions and I'm LOVING it!! Lightweight and loud. Great gigging amp.
Did he follow my mods?
@@TheGuitologist Actually no. I just shared this with him today (he doesn't get on RUclips much). The amps were already "gone through". He has been building amps for awhile. He really enjoyed your video though and he may be doing your mods to the other 645A he has. This is the first set of old PA heads he's modded to be used for guitar though which is why I searched Lafyette amps and came across your video! He has two 645's and a larger 70 watt (I think) that he's working on now.
Ahhh I can relate.
Your wife and mine are definitely related... at least in attitude towards late night / early mornin rockin.
Great conversion. Killer tones. Love it.
I still love you! And learn a lot. Thanks
Your a real badass on that guitar bud! Great video and even better picking!
LOVE the RCA banner. !
Superb job on that one....and superb playing too. Jeez!
Thanks, Sacco. I appreciate you watching. Subscribe if you haven't already, and join the crazy train!
I'm subbed since quite some time now. I barely understand what you do with your amps but I love it.
Can't wait to see you making more experiments with the Nutube.
Freaking awesome. Great vid and sounds great
Awoke this morning to ANOTHER demonetized video. They are doing it to every single one now. And they're throttling them as well. I can see the stats where they only do x suggested videos per hour, and it's capped like a plateau. I hate RUclips more and more each day. They are about to break me, I hate to say.
The Guitologist again?? They are obviusly trying to silence people like you, maybe because its in modern day interest to buy things and when it stop working then it is thrown to garbage instead of fixed, maybe because they want mean to you after you made a video about shitty mercury & cadmium bulbs (that have poison inside and slowly brainwash people and weak their health so that WHO could do shit to us and sell us "medicine" that makes you stupid. It all looks nice when they write things about helping world in media, but when you scratch the surface, you start seeing bad things, and when you get whats going on, there it goes: demonetization, lawsuits, and after that "scilencing" (wiping you from the surface of earth just like they did with Frank Zappa, poisoned him until he died from cancer...) But we must not fail, we must be responsible for a lot of global things... If you are interested go check out RichieFromBoston, he has some theories...
The Guitologist all tin foil hats aside, I think youtube throttles anyone their algorithms deem as not forwarding a liberal mindset. They’re also afraid someone may pick up a useful skill. We can’t have people actually using their brain for something other than watching fucking Kim Kardashian.
Hey Brad, you might want to have a look at this as a possible alternative ruclips.net/video/7qmcwJ7hotI/видео.html
YT are cheap and greedy bunts as far as I can tell. Fake agendas, no vision.
I am not going to pretend to understand how all this works with you tube but wanted to ask if they ever let you know why they demonetize? I have considered doing videos similar to yours but not sure if it is worth it at this point with you tube jacking with everyone.
Excellent Conversion good sir!
Nice work, and awesome RCA banner.
Another great sounding amp Brad!
I am winding up on rehabilitating a Stroboconn... the most accurate tuning system in history. Old stuff is fun to tinker with.
Cool man. Mine works great already. Got it cheap from a local picker friend.
It turned out sounding great. awesome job. Really nice little amp.
I thought so too. Turned out pretty ok.
I’d forgotten how far out of the fingerboard the trussrod extended on those Roadstar II’s. Looks like about an ‘85 to me. My first electric was a RS-II ‘84 strat copy bought and paid for with my first cheque from my first job ($280 CAN)... :) 46 Guitars later and I’m still a huge Ibanez guy... :) Great Vid!!
Your hammering technique is to die for!!! Vids please!!
The amp sounds terrific, some people just have it don't they
I think your wife has a negative feedback issue.
I've been puzzling over it for a long time. Rational troubleshooting steps get thwarted every time.
Fantastic video mate. A great conversion. Love the playing too!
Thanks man.
There were several parts of this one I didn't quite understand Brad but this was really outstanding and I'd love to have one. I just can't believe the sounds you are able to get out of this but like I said, you got into some repair areas I don't remember you talking about before but I've picked up some books and picking up a lot. Really enjoyed this video and the final sounds of the amplifier. Amazing what you can do with a 60's PA head! (That was cute with your daughter at the end of the video)
Thanks buddy
No thank you! Meant to tell you, I got the "Designing Tube Preamps for Guitar and Bass book by Blencowe" and I have the "Tube Amp Book by Pittman" the most recent coming, should be here Monday. I've picked up a lot already, the books are great and you are a pretty good teacher too. Thanks. You Rock!
Well done.
This amp + rv3 + tube screamer + 4x12 with v30s = yaaaaay!!
You always pull off crazy shit... like not using that Bertha iron for the chassis soldering. Just knowing that the shop speaker is laying down on a stool. Terrific playing as always inspired by Hoegaarden
40:53 Greeting from Hoegaarden in Belgium!
Sounds better than a lot of Marshalls I've heard!
i donno if i'm drunk or the marshal sound had more depth... but i know what i see. top job fella.
The Treble Bass Middle layout isn't unheard of, it's that way on the best guitar amp ever made! The 1986 actually has half the bias resistor and twice the bias resistor of a 5F6 input stage. Either way it's more gain for certain frequencies. The mishmash Fender/Marshall amps I've built have been the favorite amps of their owners. The 6V6 15 to 20 watt type have been very popular in SoCal. I can't take credit for the 6V6 2204, Doug Hoffman has a great design on his website that kills! There's a few of mine down here you might hear in Hollywood venues ; )
Nice work turned out great !!
OMG you got a KORG NUTUBE DIDN'T YOU? excited for the video!
Nice mod. Like them old amps back in the day they sold as kits you could build and learn electronics
DUDE! A Roadstar II. Love it.
Haha, love the title. great video as always brad.
Thanks, man.
Killer conversion !
That packing job was overkill....but much better than receiving broken up stuff.
Yeah, the double boxing was overkill probably. Added about $25 to the shipping cost, I'd imagine.
Hard to beat. Thanks Sir.
Brad you are Da Man! Great video.
Thanks, Rick.
I had a Bogen for an amp as a teenager. The look and name of this amp makes it very cool cosmetically.
All the old Bogen Challenger (well, the really old ones, BEFORE they started making solid state models and calling them "Challenger") amps are almost plug & play for guitar. Well, not almost, you CAN use them exactly as they are and get great dirty guitar tones, but it helps to at least change the grid resistors and maybe swap coupling caps if you're gonna use it for guitar. But yeah, Bogen made better Marshalls than Marshall.
Well done, nice conversion. Sounds good.
Thanks, Dave.
Brad, Uncle Doug is back!
Another awesome video Brad! Can I ask what sort of power the amp is putting out an could you state this for future vids as been trying to figure out what some of these vintage pa or radio amps put out compared to say a 30 watt dedicated guitar amp...... you seem to be able to run the master high in this video so guessing it will be less than 20 watts? Many thanks for the vids, keep up the good work.
Another great video
Hello from Hazard Ky, Brad! Really enjoy your content.
I forgot how nice those Ibanez Roadstars were minus the headstock LOL
We had a Lafayette store in North Olmsted, Ohio, in the '70s-spent a lot of time and money there-lol!
That turned out quite musical.
That Ibanez is a sleeper!
That turned out well, it sounds pretty good.
The old Weller/Ungar screw-in heater irons work very well for chassis soldering.
My 1kW Variac came in a plane white factory box which was padded with styrofoam but was apparently dropped on one corner, and the extra fuse rattling around in the bottom. With the weight of the thing I was lucky that it survived.
After seeing what you done to this PA, makes me want to experiment with my Montgomery ward airline tube amp
Sounds awesome Brad!! I like the re-purposing amp videos you do.. I like the idea period of odd ball looking pedals and amps.. Looks like a P.A. roars like a Marshall !! Going to a gig and plugging into something that looks like VCR but sounds beastly the looks you get is PRICELESS!! Lol .. I've used some odd ball looking pedals before at a gig and as soon as i kicked the pedal in afterwards i get asked what was that..??
Anyone can walk into Guitar Center and buy a Chinese, mass-produced amp these days, but something like this will last a lifetime and turn heads.
Brad - this was reckon brilliant... I'm pretty sure you didn't want to send this back to the customer ;-) Sounded fantastic ... I need to go bargain hunting for some old PA amps for conversion... Keep up the great work and I hope RUclips stops demonizing, er. I mean demonetizing your videos :-( :-( !!!
I'm pretty sure that chassis and output tube slanted socket area are aluminum. The leads that were soldered (for the first time) are touching the chassis but solder will not stick to aluminum so may need to tie those to the chassis with a bolt or run a wire...
Good thinking, but no, it's steel. It took the solder fine. The solder will just bead off aluminum.
I would clean out the solder splodge / drip you made + clean off the solder flash that is sitting on the wire below your soldering. before switching anything on.
I Have a '60s Lafayette Stereo Speaker w/ a 10 " Norelco Oval-Shaped Speaker that Really ROCKS !!.......Lots of BOTTOM !! Also Have a Lafayette "MONSTER" Stereo ( Quad ?) Amplifier w/ 5 Fuse Holders / 2 Aux /2Phono / 2 Tape / 8 Speaker Outputs..........I Can't Get to the Front to See Model #...........HOARD Prevents That @ This Time.........Front & Rear/ Ceramic & Magnetic Phono Hookups........Dammit !! I'll Be Digging This Out Tomorrow..........Got My Curiosity Aroused !!!!!!! Hopefully It Functions Completely ?? Love the Channel Brad ......... GREAT JOB !!!!
Dig for your life!
Love your vids Brad.
Oh CRAP that thing sounds good.
Good job sounds great .
You took it for zero to hero. That's one I'd own.
That's A Killer Amp Great Mods!!!!
The '70' and '25' lugs on the terminal strip are for 70 and 25 volt, respectively, distributed audio, commonly used in institutional and industrial applications...along with some churches on a budget. The output of the power amp is tied to an autotransformer, then each speaker has a corresponding transformer, with taps labeled 1/2-watt, 1-watt, etc. In theory, therefore, such an amp, if rated, for instance, at 100 watts, could handle 200 transformer-isolated speakers, tapped at 1/2-watt (although, in practice, you never loaded an amp to more than 80% capacity). The jumper tied to the 4-ohm lug was often set up that way to enable the 25-volt output of the autotransformer. Disconnecting it would allow you to connect a 4-ohm load, or use the 70-volt output. The fact that it was connected probably means that the amp was being used either as part of a school intercom system or the page circuit of a fire alarm system, bot of which typically used the 25-volt circuit...that allowed connection of 8 times as many speakers. The entire science is WAY too long to post here!! This is the stuff i worked with (along with 'Pro' audio, and a number of other low-voltage systems, for over 40 years...including stints with NSCA and Lincoln Tech, as an instructor.
BTW, the autotransformer output's downside is that it is very strong in midrange (primarily designed for spoken word, and maybe a little low-fi background music), but weak in highs and lows, making it a very 'so-so' guitar amp, at best.
Sounds pretty good, i would also add a tremolo, perhaps you could even do a harmonic one.
Outstanding
I bet ya Korg sent you a bunch of those nuTubes to play with, can’t wait to see what you build with them.
I can't wait either...but I have to push out customer stuff first.
Negative feedback - from the wife! Oh Lord.. I remember those days..