1983 JCM 800 GT-65 EL34

  • Been using Kemper for 2 years. Never really dug into profiling though I had good results the first time I tried. Decided to drag out my JCM800 4104 that had been graciously and thankfully inspected by one of the worlds top amp techs of the stars. I installed an FX loop and switched tubes to EL34 properly following all the original schematic and values. Bashed off a profile using inexpensive preamps and condenser mic and I thought that it sounded pretty good and thought I'd share. Let me know what you think please. Profile name: JF 83 4104 3

  • Yes ! Thx it's approved here and I already record a track out of it :)


    I like JCM800 very much and this one has a dark voicing, just like I dig.

    I could have easily made it very bright but I like the darker as well. I think the Presence and treble were 9-10 o clock. Most people (and even amp techs)I've spoken to don't realize the strange EQ centers of those amps. Bass 50hz! Mid 500hz Treble 10K and Presence 3K. Most assume presence is going to be the highest control but actually it's like upper mids. I was pretty surprised as I was using an inexpensive console preamp. Not bragging but I thought it held it's own against many professional profiles of similar amps, plexis and super leads. In comparison I think it could be louder overall, but that's fixable. I was thinking about making it brighter but I profiled it comparing with some "made for live" P.A. darker professional profiles. It's easy to add some sizzle to it. Gain control works pretty good. I was looking to capture that old boxy fat Marshall tone I love. Eventually I'll try my NEVE preamp (I don't know how much that matters to profiling) and go for a more open tone. The volume was not very high and amp sounds good that way, I think it was on 1. (still loud) Once you get that amp at about 11:00, it sounds amazing but is difficult to tame. Thanks for checking it out I was hoping it wasn't too dark and was curious how others would perceive this. The FX there are what I use as a default. don't have a big delay but a short one that can be used with the reverb to make everything bigger without really noticing the repeats. I'd augment it if I needed say a big tape delay or something.

  • Very useable in a mix. I am able to get Cry Baby leads and nice harmonics with just a treble booster in the effects to cut some original darkness.


    For my flavor, I dropped the gain to 3.0, added a 0.0 Green Scream at 100%, Pure Booster at 2.1, and my fav delay and verb settings. Gets me 95% where I want to be for hard rock - heavy metal.

    The more you find what Kemper can do then the harder you try to find what it cannot do -- like make a good cup of Frappuccino.

  • Very useable in a mix. I am able to get Cry Baby leads and nice harmonics with just a treble booster in the effects to cut some original darkness.


    For my flavor, I dropped the gain to 3.0, added a 0.0 Green Scream at 100%, Pure Booster at 2.1, and my fav delay and verb settings. Gets me 95% where I want to be for hard rock - heavy metal.

    Wow, that's awesome! I love to hear opinions and ideas on how someone else "sees" and manipulates tones to their ear. Having a clean ear slate, I A/Bd it against some universally favored paid profiles and believe that I need to open up the top mids a bit more. Maybe the whole top end. (easy with this amp) Although I have only done about 6 profiles ever I am starting to understand what makes them "tick". Most likely if I just crank the 800 some more it will do what I'm looking for automatically. When I get time I'm going to dig in and get a more snappy harder profile of this amp. I'll share it when I do.

  • I A/Bd it against some universally favored paid profiles and believe that I need to open up the top mids a bit more.

    This is where the Profile selected when you switch to PROFILER mode kinda matters.

    It doesn't matter tonally at all, let me stress that, but it gives you an easy way to A/B your amp/mic settings to let's say the 'Mars Golub Crnch' or any other proven Profile and gives you the opportunity to make adjustments on the amp or the mic position etc. before Profiling.

  • This is where the Profile selected when you switch to PROFILER mode kinda matters.

    It doesn't matter tonally at all, let me stress that, but it gives you an easy way to A/B your amp/mic settings to let's say the 'Mars Golub Crnch' or any other proven Profile and gives you the opportunity to make adjustments on the amp or the mic position etc. before Profiling.

    Agreed. It gets your ears better aligned. You wouldn't want to start with a flender and profile a rectofrier. It helps to start with something you are familiar with for a sonic base point. It was fun and easy to make a profile. I can see how it cold get addicting. After profiled, I compared it to 'Mars Golub Crnch'. Could you tell me your opinion comparing them?

  • What was your opinion on my reverb/delay? Too much rev?

    Honestly, I didn't even try it. I always load my presets first.


    BTW, I raised the gain to 4.1 so I could roll off the volume knob down to the 3.0 where I adjusted to on the first test drive. I'm using SD Distortion and SD JB so they're pushing the amp pretty good - that's why I backed off the default gain initially. The only tweaking I feel is left to do is to tighten up on the low E string. I always seem to get too much flub for my ears on that string no matter what gainy amp I use with those SD pups.

    The more you find what Kemper can do then the harder you try to find what it cannot do -- like make a good cup of Frappuccino.

  • Had some time so I added one using a lynchback speaker and my Neve preamp (don't think that matters). Went for a louder,brighter tone but the lynchback is a dark Greenback type speaker. When I get time I'll do my favorite cabinet/speaker combo. The first one was the stock speakers,this one a closed back Lynchback. JF4104LB Make sure to mess with the gain knob and add the delay for leads. It's small, and the way it works with the reverb it doesn't walk on notes and makes it sing. Thanks for all the kind comments, profiling is fun and It's fun to share and get opinions.

  • Very cool that you are getting into this. I have not tried the profiles yet because my Kemper is away from my good speakers. But the first real amp I owned and loved was a JCM800 50w 4210 combo. It needed some love and I had a Pod XT Live so I gave it to a friend dirt cheap. Eventually I bought a DSL40 because I missed the JCM800. The DSL is no where near as good. Totally different animal. So I will definitely check these out in the coming weeks for sure. Cant wait.


    I bought the Kemper to play and record but spent 99% of my time making profiles. It is so much fun and addicting. Dont be afraid to EQ stuff after the mic etc. Go nuts. I am sure they dont just shove a 57 at the cab and go at a studio.

  • After profiled, I compared it to 'Mars Golub Crnch'. Could you tell me your opinion comparing them?

    I compared the Golub and the JF4104LB and to me it sounds very, very good.
    here are the adjustments I made:

    • switched Reverb off
    • increased Definition to the Golub setting (6.1)
    • added 4.5 dB of Low Gain @ 102.5 Hz with a post AMP EQ (I have the Low Cut in the OUTPUT set to 49.9 Hz), so now it has a very similar contour as the Golub
    • Pure Cabinet is at 3.5 - I regularly switch this on and off and I just like and prefer what it does :)
  • Very cool. I have since "revised" it myself. I turned the gain up to 6, added a bit of clarity bit of compression and bit more definition, also turned the pres & treble up like 1db or so. I wasn't crazy about this profile at first but now I like it as much as anything I've ever bought or more. Some people have a distaste for Reverb and some have their tones bathed in it. If you listen to the delay alone it's like about 2-1/2 repeats depending on how hard you hit it. I usually like to cut it so it's like a worn tape echo which I love. When you mix that with the reverb I don't feel it steps on what you are doing and the delay isn't obvious. I'll have to try the pure cab on it, I tried it a couple times and just ended up forgetting about it because with the profiles I use there hasn't been an issue to fix.

    I tried some different preamps and cabs last night (focusrite and my favorite CL-80 cab) and made a couple horrid sounding profiles lol. The Neve worked out good with the LB cab but I'm not sure if it made things any better than using my Xenyx preamps. That Lynchback gets a little stuffy in the small closed back ported it's in, and it's dark so that when you get it cranking it isn't strident and stays smooth. I want to give my CL80 cab another chance, my setup was obviously wrong. Since the Xenyx pre just has a clip light , it takes me an aborted profile to set the gain correctly. Profiling gets loudest at that one warbling stage and I turn up the gain at that time so the clip light barely flashes, then cancel and repeat for the first setup.

  • Thanks for posting this! Which one did you use?

    I did a cleaner one that I liked with the gain on 4 but I didn't post it because although I thought it sounded pretty good, I didn't think it was worth showing off. Now that I have made couple profiles that are OK and a few that were not that great, I don't understand why the Kemper doesn't have phantom power. I have not been able to get a great profile with a dynamic mic. On the "cleaner" 800 profile I mentioned, I used a I5 right into the Kemper and it sounded pretty good, but for my limited profiling experience a powered condenser mic creates a much better sounding and predictable profile. I've tried using really good preamps and had the best luck using a cheap mixer & pretty good condenser mic! Although I find the GT65s a bit too crisp for that already crisp Marshall, they profile better than my other two 1x12 cabs which sound awesome in the room but didn't profile as well in my first attempt to use them.

    If you want, I'll upload the cleaner one to check out, Since I had the dynamic mic and darker cab set up, I worked to get a brighter more open sound on that profiler. When I get in the mood to tinker, I'll set up my original rig and try to capture that amp better, it really sounds good and "changy-er" than I've captured so far.