NAD: Modded 1987x

Discussion in 'Marshall Amps' started by lonewolfsx, Nov 19, 2020.

  1. lonewolfsx

    lonewolfsx Well-Known Member

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    Just got this 1987x earlier this week. I usually have a bad track record with buying other people's old modded amps, but this was another guitar center find so I figured if I had to I'd just take it back.

    Luckily, I won't have to, because it sounds great. Very dynamic, really sweet sounding, count me a big fan of this tone. I did a little comparing to the crunch channel of my 6100 (supposedly has a JTM45 and 1959 modes) and the JTM45 was a little closer, but neither has quite the fullness and roundness of the actual 1987. I actually think the JCM900 SL-X was probably the closest sounding as long as the gain was turned lower, but that's just a first impression.

    The amp is almost completely hum free and I also have to give Marshall credit as well, chassis mounted tubes and pots, very neat PCB with quality soldering etc, it's a very nice amp. This one dates from 2003 and looks to have all of the original stuff inside other than the mod, dagnall transformers etc. I'm also pretty thrilled by the small box format. It's a bit smaller than the average Marshall head shell like most of my amps and the small chassis is nice and light too.

    The master volume added is mounted where the low input for Ch2 was, so the jack is gone now. I'm still having trouble deciphering exact which master volume mod this is, but the work inside the amp is super clean, nicely done job. It's a 1meg single gang pot, with two wires from lug 1 & 2 running over and soldered directly to R23 and R24. I assume underneath the board it's been wired over to the power tube pins as well but I haven't taken the board out - at the moment I'm not going to mess with it because it's fine.

    Even with the master volume though, it's extremely loud, and of course bright. It doesn't have a great taper but I threw a volume pot in the FX loop and just use that instead and it's a bit more manageable. I'm actually quite surprised just how good it sounds, considering I'm essentially using two master volumes in sequence to tame it down to around 100db. I'm sure it'd be a little better with an attenuator but I'm still impressed.

    The only other mod I can find is the bright cap has been cut out entirely. It's plenty bright and I find the presence control to be reasonably usable on this amp compared to some other stock ones I've played in the past. The bass that comes through isn't flubby and I'm very happy with how thick and full it sounds without it, though I may clip one across just for the sake of trying out what it would've been like stock, after hearing Johan Segeborn's clip I'm really torn on whether I like the cap on or off, so I'll have to hear it in person.

    Before I put it back together I may try the one-wire cascading gain mod. If I really like it I'll look into making it switchable. The other alternative is I may remove the MV, or at the very least rework it a bit. Only the high treble channel inputs work, and they work like a normal plexi, but the normal channel input is just grounded out, so you get nothing from that jack. Of course, raising up the normal channel volume does have a slight effect on the tone, adds a tiny bit more fullness, so I'm just running both volumes maxed. Great tone to my ear. I think ideally though it'd be cool to still have access to the normal channel though. I don't want to mess with it too much because it sounds really great as is. I definitely won't be drilling any new holes but reversible mods are fair game here.

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  2. tce63

    tce63 Well-Known Member Gold Supporting Member

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    HNAD, Congrats.

    Looks fantastic.
     
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  3. neikeel

    neikeel Well-Known Member

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    Looks like a simple Crossline MV, as you say the grid wires will under the board. How does it sound fully cranked?
    There is no reason why the normal channel should be inactivated. If you are considering a cascade mod that is switchable take a peek at the 2 in 1 mod as it is easy to implement and to reverse if you want.
     
  4. Drinkingdeath01

    Drinkingdeath01 Well-Known Member Gold Supporting Member

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    Congratulations on the new amp !!!

    I have a couple of David Hopkins Pandora modded Plexi's and something about that circuit modded just sounds incredible.

    Have fun and crank her up !!!
     
  5. CROWEMAG

    CROWEMAG Well-Known Member

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    Let's hear it!
     
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  6. lespaul339

    lespaul339 Well-Known Member

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    Congrats! Looks like a nice score!
     
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  7. JacksonCharvelAddict

    JacksonCharvelAddict Well-Known Member

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    Is the mod just for the Master volume and the bright cap? Interesting find. Looks like a really clean amp. I bet that baby gets loud.
     
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  8. lonewolfsx

    lonewolfsx Well-Known Member

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    Thanks everyone, super pumped about it.

    I don't think I'll ever find out what it sounds like fully cranked. With the MV up at half it's already unmanageably loud at home. Maybe I'll take it downstairs to the living room and put a baffle in front of the cab and try it there. My studio room probably isn't big enough to really blast it. (I do have earplugs though so maybe I could try it on a weekend when my neighbors aren't around)
    I've seen and saved a schematic of that 2-in-1 mod, involving a push/pull pot, looks really cool and since I don't own a 2204 it'd be pretty awesome to switch between the two circuit types (individual component values not exactly the same but still). That's probably the way I will go with it but I'm enjoying it so much at the moment it'll have to wait until after the honeymoon period.

    You can bet I'll make a video! I have some ideas to improve the sound quality as well, I'll share it here whenever I have the time to record it.

    I think so - I poked around inside and referenced the schematics and really couldn't find anything else out of the ordinary. Considering those are two mods I would've done myself if I'd gotten it stock, I'm pretty pleased overall. It does get incredibly loud even with the MV, which basically does nothing the first 1/4 of the travel, then it sounds weird and thin, then suddenly it sounds great but it's already super loud. Definitely not a "bedroom" friendly amp but I knew that going into it anyway.
     
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  9. Mitchell Pearrow

    Mitchell Pearrow Well-Known Member VIP Member

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    Congratulations on your new amp score brother.
    By far my favorite amp !!
    Cheers
    Mitch
     
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  10. lonewolfsx

    lonewolfsx Well-Known Member

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    Oops - just realized that on this model the bright cap is on the board, C5. So it's still there, looks like the stock value 4n7 too. Sounds good to me!
     
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  11. Kelia

    Kelia Well-Known Member

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    Beautiful ,........Congrats ! :applause:
     
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  12. C-Grin

    C-Grin Active Member

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    Congrats!
     
  13. junk notes

    junk notes Well-Known Member

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    Congrats on a great amp!
     
  14. Biff Maloy

    Biff Maloy Well-Known Member

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    I bet it does sound great. I've lusted for one a while. Definitely keep us updated. Congrats!
     
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  15. crossroadsnyc

    crossroadsnyc Senior Moderator Staff Member

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    Good Lord, man, you have a lot of amps listed!

    HNAD!
     
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  16. matttornado

    matttornado Well-Known Member

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    congrats! that is one sweet amp you have there!

    I agree that you have a "cross line" master volume. The nice thing about that mod is that it's only two wires from the pot soldered to your PI Coupling caps/ bias reisistors. very easy to remove if you ever wanted to get that input jack back for linking channels or other tone options.
     
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