How I build a JTM45 Amplifier.
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- Опубликовано: 7 окт 2024
- This is how I build a original JTM45 Plexiglass Marshall amplifier to sound exactly like the original amplifier of the past.
There are many special circuit design changes needed to be made in order for the amplifier to sound like the earlier original JTM45. This is due to transformer manufacturing changes from Marshall manufacturing and other component changes as well.
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I have always loved the High and Dry tone. Perfect choice.
The og def leppard was much appreciated, this is the whole reason why I just want to build one
I always pre-wire the input sockets outside the chassis by simply mouting the from the front. Then you perform all the soldering for wires and resistors. After completion you mount these on the inside of the chassis. Also for the turret board I prefer to solder first the reversed side with all bridge wiring, after that placing the components and solder these. At last you solder all the external wiring for the pot's and tubes etc
Excellent procedure.
OMG, this is how I build my two amps, but didn't want to share it ! There's way too many folks in negative inputs ! However, I found wiring is more enjoyable!
What do you use or like to use for the pt and ot? I want to start my build soon and I have Classic Tone 50 watt for output transformer, I hear they sound nice but I've never got to experience that myself yet. Thanks for the upload.
I think it's very important what you do, theres not a whole lot of people my age that take time to appreciate the ingenuity and time that comes with engineering/ reverse engineering something so precise as an amplifier that most people beat the heck out of and take for granted on a daily basis. Big thumbs up, b👍cause You R🤘ck!
Thanks for uploading this! It was fun to watch your process!
It is my pleasure!
I had One, with 2 Mullard tubes (I forgot the model : 6l6 or El 34 ?) Please Marshall help me) the sound was Creamy at full volume, nothing like today. It did not hiss or buzz. Unforgettable. The Who had those. Ken Bran you did magic; Say something if You are alive,please. i never Blow a fuse and never change tubes. Point to point it's the only way to make good and sturdy Amps . Anyway thank you.
very nice build !! I built a jtm 45 with kt66 tubes to be different than every other one I was seeing
I ended up making the preamp cascade and added a ppimv master volume
the original version just did not give me what I wanted Its now a keeper not a super lead or an 800 but its nice all on its own
Thank you!!! I don't like the orange drops at all. But I really like the mallory 150's for fender amps. I also like the F+T electrolytics everywhere they are appropriate. Vishay make good stuff too.
So this is a mojo tone kit amp with a few upgraded caps. From my experience, it's much less expensive to compile the parts yourself , you can end up with higher quality components and spend less overall. It's certainly easier to just order a kit, though. I'd recommend a kit if you are new to building amps.
If you want to find out what's under the mysterious painters tape, you can google a jtm45 layout diagram or schematic. There's no magic sauce.
If there are differences under there , it's not a jtm45. Maybe it's a jmp of some sort.
Excellent advice as far as compiling individual components go. That’s exactly what I will do. However, there are multiple revision performed to the original circuit design. These are predominantly in the preamp stage and voltage divider sections. I will create more content surrounding these revision.
It's a common cascade
Yes. So,this amplifier was designed to sound like the original JTM45 of the early 1960s. However. To achieve this one must jumper the 2 channels together and crank the amp to around 6 on volumes 1 and 2. I eliminated the need to do this by creating a circuit that could be played at low volumes and not need to connect the 2 channels together externally. All engineer technicians know how to do this as I mentioned in the video and each technician is very protective of there own circuit designs. Also, we never share each other’s designs due to...
Sort of 2204 preamp with sort of bass specs values mixed and a rc circuit on the NFB . Not a jtm45 at all
Great vid! You make it look so easy. Is teh blend between the two volumes fixed then? i think one of the volumes is like a MV and the other is the traditiona volume at fixe blend ratio?
0:05 the logo not being perfectly straight always fucks with my OCD big time
4 eyes 👀 and I still can’t see straight. At least you know that this is truly a hand built JTM45!
@@FeeserAmplification haha no worries, that's what makes it special right?
yes the blue tape mod could you tell me how to get the pio caps
Sounds great 👍🏻 how does it compare with Marshall JTM reissue sound wise....
Yes. So this design sounds like the mid 1960”s JTM 45. There seems to be a lot of complaints from the owners of the Marshall reissues. Unfortunately the reissues have nothing to do with the originals. For example. The reissues use a duel 50 uF in the power supply filter stage. This not only changes the JTM 45 character but also puts a lot of stress on the tube rectifier.
Yes I agree yours sounds better I don’t think the re-issue sounds that good, It be good if you have them side-by-side demo to compare sounds, there is a company that makes a Rola clone here down under in Adelaide
Great work. Why do you put Marshall logos on your amp? After all it’s all clone and no original. That makes it look like a fake to me…😏
The Marshall logo is a customer request. Normally all amplifiers that I build carry the Feeser Amplification badge.
@@FeeserAmplification That’s funny, your customer is faking himself! 😂🤣
@@MW47742 Agree....sort of. Lots of people just like to feel the mojo of the original rather than wanting to fake things. I don't do it - it's like Elvis and Beatle impersonators donning bad costumes that insult the originals. Even when I recreate a capacitor, I do not "stuff" - I fabricate a period "style" jacket with differences and label it with the actual capacitor inside. Even that is vanity but a compromise in respecting the vintage while not trying to fake anything or anyone. I'm kind of ok with the Marshall badge here because it emotionally feels good yet is an obvious clone inside. Hopefully the owner doesn't try to re-sell it as an original to the unwary.
Ahh I see what your hiding,,,, more rusky paper and oil caps, very interesting Watson!
What mods did you do? Sounds with more gain
It's really a 2204
Hot preamp bias or cascaded input
Sorry but that amp is not a JTM45.
you got that right, I was thinking the same thing the moment I heard the first note played - the rest of the video verified what my ears heard (split cathode, V2A bypass cap) - more like a tube rectified 1987/2204 hybrid. Nothing wrong with that but a completely different beast if you know how a real JTM45 sounds like (even the late '66 transitional ones with the Drake -128 OT running EL34s).
Snubber cap on the cathode follower plate resistor, 33K slope resistor (presumably accompanied by 500pf in treble), different feedback with added "resonance" cap, another snubber in front of the tone stack in parallel to the cathode resistor, no cap on mixing resistor, a voltage divider on it, etc. I can be wrong about something but only one of those things already makes the amplifier different from a JTM45.
is that okay to use 200V rated caps in PI?
Excellent catch! I was waiting for someone to notice the voltage value. This particular capacitor is for research use only. I highly recommend that you exceed this value by using only capacitors rated for 630 volts in the phase inverter stage. Very good observation on you’re part.😀
@@FeeserAmplification i see these quite often living in Russia)
Very nice build. Where can I get some Russian paper & oil caps?
You can get these from me. Just send me the address. If you need a batch then go to eBay😀
Hi Eric, I have a Ceriatone JTM 45 60's schematic amp and it definitely doesn't have this kind of gain. I was wondering where I could buy some of those Russian paper in oil caps or the Solen caps you suggested. Thanks Michael Newell from Niagara Falls, Ontario, Canada
Hello from Eric’s Guitar Amplifier Repair,
Believe it or not I get all of my Solen caps from Canada! As far as the paper and oil caps. I Aquire these from Russia through eBay.
I can send you the above caps if you just need to mod your personal amp.
Just use the link above. My business email is under the contact page and just let me know where to send😄
Cool?
Eric-
eBay of course😀
Why does it say Marshall on it? That's not honest.
Would you feel better if I changed the name?
Im looking to get my first Marshall head, coming from Fender amps,and Mesaboogie amps, witch i still own.I found a Marshall JTM-45 Clone with KY-66 Power tubes ,built by Trevor Labovitz.Will this head give me the classic Marshall Crunch im wanting? “British sound”? Or should i go for an old JCM-800 like my Uncle recommends? I hear that i can convert the JTM-45 clone to EL-34’s with a bias adjustment? Maby that will give that crunch?
Jtm45 will be very clean very loud until it’s absolutely cranked and possibly boosted. You probably want a 6knob JCM800
@@TheFunnyzach Thank you , i ended up with a Splawn Quickrod 100, basically a hand wired JCM800 Type amp, with 3 different hot rodded jcm800 voicings, and 2 channels, dual power levels.I love it.
I might build a Mojotone or an Ceriatone Marshall head kit as well
Sounds great but doesn’t sound like a JTM45
The orange makes it look like an Orange amp.
Totally 😀
what's the red substance? nail polish?
The red substance is locktight.
@@FeeserAmplification well that was a waste of time. I used the red loctite on my bolts for PT , OT etc. and the stuff doesnt harden, stays liquid for 2 days now. I'm gonna wipe it all off
@@johnmiller9219 Oh my God! So lock tight is a thread locker used specifically for high vibration environments. This is the first time I have heard about lock tight not curing. I have seen some of my colleagues apply there girlfriends nail polish on the fasteners. However. I’m not sure if nail polish will perform a long term hold on the fasteners.
That amp smokes. orange is sick. Leave the logo.
Def Leppard Let It Go and Another Hit And Run right out of the gate... fix my JCM 2000/DSL100 (needs new motherboard).
Send me the amp and I will take care of everything for you😀
@@FeeserAmplification What's your charge for this? I have the Revision 20 motherboard already.
@@scottdunn2178 www.feeseramplification.com
Than
what power tubes? kt66?
I chose the Black flag Marshall as the original inspiration for the build. Thus I chose the EL34 electron tube.
interesting @@FeeserAmplification