So, how have you liked the Amp since? Have you done any other things to it since also? Also, just a couple more suggestions, I've been sort of collecting data on JCM900 mods for awhile, and seems like changing the 250V Bias Cap to a higher value is pretty important. I mean, mines been fine for a long time without it, but I'm planning to do it. Theres like 300 and something odd volts on it, so it's fairly underrated, and a lot of people get bias drift, or it straight up fails. Next, I don't know about the 50W, but on the 4100's, two resistors that are on the board should actually be on the tube sockets themselves. I think R25/R26 on the 4100's. I know that on the 50w because of this, one tube gets slapped a lot harder than the other, and with the 100's, I think it's 2 with the 4100, because I could always tell two tubes were always working harder by the way they looked, so I always rotate the tubes, but this mod will fix all that. Lastly, with the 4100's anyway, I noticed a couple years ago my Power Caps were wired wrong from the factory, and then noticed it in a bunch of them since. The 50w's likely don't have this issue, but just pays to check, but if you ever get a 100w, definitely check. If it's wrong, one half of one of the Caps will not be used. So one will be using the full 100uf of the 50uf/50uf, and the other will just be using one side(50uf).
People who are unhappy with their 900, 2000, TSL, etc... Before modding or getting rid of your amp, it's always a good idea to experiment with the one thing that influences your tone more than anything.... try different speakers! Speakers and even the cabinet can make a huge difference, especially if you have a matching Marshall cabinet with T75's which many consider flat and/or uninspiring. That or an EQ pedal can bring otherwise "meh" amps to life.
@@madjack4691 So? Then mod it. Plenty of people like the 900. All I'm saying is try changing your speakers first. I feel the same way about certain speakers. The T75, Seventy 80's, even v30's can make harsh amps worse.
Yeah i will mod one soon ! I agree with you my friend ! A bad v30 can sound harsh. But the 900 is not as good as a 1959. Op amp in the 900 with silicon diodes kill the pleasur to play.
@darthshredder3778 you spot on and people have their say with full negatively because they think they are right, they know better. What I can say is that there are marshall and marshalls and every amp is diferente also people mod their amps because its normal this is what people like to be inspired to that tone and requirements. But instead of commenting negative they should have done what you did . Give knowledge ❤ speakers can just be enough to change an amp. My best advice to mods and changing sound is an paraeq on the fxloop. I have one always with 4mc it just do so much ,love it. I am here because I bought a marshall jcm900 2100 and I am going to mod it , that's why I am watching a few videos.
@@redsilverjack Thx... I appreciate that. I'm not against mods at all... like you said... just sharing some knowledge. Not everyone has the means or access to amp mods and I thought I'd share my experience with how speakers and/or an EQ can make a world of difference. Thx again!
I've had the same amp...since 1990. And I'm very happy with the high gain lead channel! If I want more sound, I'll use my JVM 205. But I don't think it's necessary to modify the JCM 900. Then the beautiful character is gone.
I don't really understand the hate for the JCM900. I liked it, but I had a few other amps (Mesas, an Ibanez TN120 Thermion - really cool amp I wish I never sold!) and I found myself going back to it less and less. I think these mods give it a voicing I like without taking away the character of the amp. I just really need to clean the pots now!
Agree, 900 is perfect just how it is. I have two, 50 watt MKIII Master volume and a 100 watt dual reverb perfect, run. A clean boost and let it rip. Use EQ and damn.
@@epasternak4206 The Marshall JCM 900 III is the predecessor of the JCM S-LX! I had it in my closet for 10 years...10 years! This is a roaster! Unfortunately you can only play one sound with it :-( And the 2 master volumes are not really usable! The amp is too boring for me...and I sold it!
Get yourself a GT-7025 preamp tube and replace the V1 on that 4500. I promise you will love it! It made a massive difference with my 4500. So much so it raised the hair on my arm as I tried it. I had to put the old one back in to make sure i was hearing what I heard. It went back to sounding like a wet blanket was over my speaker cab. Then it really opened up when putting that 7025 back in. Also do you run the effects loop jumpered when playing? That makes a massive difference with these too!
Mod sounds better, more open gain structure, more natural sound, not "choked" sounding like stock. Also less of the crashing chainsaw highs, the highs sound great now.
Bruh...sick video! I'm picking up a 4500 this week for a trade I'm doing. I am going to do these mods and your video rocks! I have the JVM410H, I wish there were videos of dudes doing some mods on that like yours. Thanks!
Hi, great Video, I use my 4500 HGDR always on 50 watts, no matter what. It's way more punchy at that setting, but it really awakes, dialing the MV-pot past 6 (2 o'clock). Cheers from Münster, Germany Frankie
♠🍀♥ Thanks for doing this video, the JCM 900 is actually a good amp. I started using these mods three or four years ago but never finished the video. The JCM 900 was a new approach mainly because of the preamplifier with the transistors and some extras that became increasingly popular as mods since the seventies. Not a bad first attempt but there is still a lot that can be improved. Normally I mainly recreate Lemmy's amps, but I did the same thing with my son's JCM 900 and my guitarist's JCM 900. From the factory there are two problems with many of the 100W models that should be eliminated. There is a great video about this, I hope it's okay to post the link here, it might save the lives of some JCM 900s: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xGJ1kMWYAxg.html I changed a few other things on my son's JCM 900, but with the preamp it took a lot of time to tune everything so that the different mods fit together, but now it has a lot more low end and power, a real beast, which is also great for Drop D or Drop C tunings. However, playing clean is still possible and the bass can be reduced using the bass control. I converted the power amp section to JCM 800 specs and it was also a good thing to install a choke. Apart from the preamplifier, the 900s are actually classic Marshalls as they have been built since the 60s. Replacing the large filter caps can also make the sound fuller again in older amps, they go bad after 20 or 30 years, especially if the amplifier hasn't been played for a few years and is then immediately put under full load again.. If the amp has been played a lot and loudly, it is a good thing to replace and bias the tubes, then your amp will work like new again. Greetings and best wishes :) 🎸🎛😲
I didn't like the diode bridge jumper. It muddied it up so I left it in the circuit. C27 jumper added too much muddy low end. I removed the jumper. R7 did nothing to my ears so I left it in. The R43 jumper was the best of his mods. Fattens up midrange nicely. If you want to really thicken up the channel B you need to raise the C9 coupling cap value. Stock is .22uf. I jumpered a .68uf over it. Now the gain channel has nice thump without being muddy. Give it a try u will like it. I alligator clipped different values and settled with the .68. it lets more midrange thru and removes the sizzly upper frequencies. Everybody perceives tone differently but I found the c9 mod a night and day improvement.
bought yesterday a marshall jcm900 2100 cant wait to have it also that ibanez but 7 strings and fixed bridge killlller guitars 11 piece neck etc etc etc just amazing .
I had to wade and search trough forums all day long to find out which mods I'd want and hiw to do them. So great video! I also want to point out that the G12T75 speakers aren't the best sounding to go with this amp. Changing to another speaker will be a huge benefit for the sound.
Improvements?? Sell it, buy a Plexi replica of one kind or another, buy a reactive load box to tame the volume, crank the volume, throw a boost in front if needed and you will be in amp heaven.
Should try a quality eq pedal,.... a different cab,... different speakers,...etc. Only thing I run with my JCM 900 50 watt combo is a wah. If I am running pedals,..my Hiwatt.
The modded sounded I'm hearing is a little more harsh to me than stock. So hard not being there in person to hear and feel it. But I wonder if harsher sound is fixed with an EQ adjustment. Muffled or blanket-covered sounds can't be made brighter, but brighter amps can always be dialed back even with a tone knob on the guitar (unpopular opinion). I'm just unsure if this video motivated me to try this with my JCM900.
I hear the same ... it is worse. i have this amp i removed the channel 2 fixed tone stack and i love it, before i only used clean with OD pedals and that worked great
Improvements?? Sell it, buy a Plexi replica of one kind or another, buy a reactive load box to tame the volume, crank the volume, through a boost in front if needed and you will be in amp heaven.
@@AltaroftheBeast If you crave VH roar then you may reconsider. I finally bought a Germino late 2019. My Soldanos, Hughes & Kettner, and EVH gather dust now. Never say never. You may be in for a shock.
