YJM100 - 'The Ultimate Plexi' thread!

[Redstone]

Have you tried turning up the Vol 2 a bit? I usually keep both volumes at about 7. If I turn Vol 2 up to about 8-9 it sounds super bassy. Mine sounds pretty much the same no matter where the EPA is, although it sounds a bit more ballsy with the EPA turned up higher. It doesn't sound bassier, but ti does cause a lot more vibrations rattling the room.

If the autobias doesn't work I'd take it straight to a good tech and get it sorted out.

Before you use the auto bias, check where the little bias trim pot is set. It should be set roughly in the middle. The bias trim pot is the little white thing under the EPA dial. You can use a thin guitar pick to adjust it. Make sure you run the autobias after you adjust it.

To run the autobias, just hold down the FX loop button and the 100/50w button on the back of the amp and flick the power switch. Keep holding the buttons for a few seconds, 4-5, and it should be doing its thing. You should see the 4 little red lights flickering on the back. Give it 5 mins or so and it should be biased.

If that doesn't work, it looks like its tech time unfortunately. If you are in the UK, I'd suggest taking it back to the store you got it from. It is probably still under warranty and they can send it off to Marshall to get fixed. If you are in another country and don't have a good tech that you trust, bring it back to the store and they will either send it to a Marshall verified tech or direct you to the tech.

I hope you get things sorted

 

[Odin69]

OK, I bought a YJM100 two weeks ago based on all the praise on this thread and many video's posted...but... I have to say full volume yeah, it's unbelievable for sure. Full on plexi tone without a doubt. What I'm terribly, terribly disappointed in is the minute I engage the EPA, even just a "bit" all my bass and fullness disappears and it sounds like a crappy POS. I mean really bad, thin and useless. I play out every week and was really looking forward to bringing this to my gig, but at full volume I'd be 86'd in a second and my bar let's us play LOUD, but this thing is ridiculous.

So, what am I doing wrong that I can't get decent full sounding tone at a lower volume with the EPA???!!!? I mean it's seriously useless. I'm better off lowering the volume and using a pedal in front to get the distortion I want, but that completely defeats the purpose of this amp. What am I doing wrong?

I have a THD hot plate that I use on one of my other amps. For sh#ts and giggles, I hooked it up a few weeks ago to my YJM, when a couple of guys on this thread where talking about using attenuators. I turned the EPA all the way to the right and set the hot plate to -16db with volume of the hot plate over half way on. I didn't think there would be much of a difference but, there was. It sounded a lot better IMO. The only down side was, one of my power tubes went bad and I had to swap them out. They were the orginal tubes and I've had the amp for about a year and a half now so, it was about time for a tube swap anyway. I haven't had much time to play lately but, I might experiment with using the EPA and hot plate together at different settings to hear how it sounds?

 

[JimiRules]

OK, I bought a YJM100 two weeks ago based on all the praise on this thread and many video's posted...but... I have to say full volume yeah, it's unbelievable for sure. Full on plexi tone without a doubt. What I'm terribly, terribly disappointed in is the minute I engage the EPA, even just a "bit" all my bass and fullness disappears and it sounds like a crappy POS. I mean really bad, thin and useless. I play out every week and was really looking forward to bringing this to my gig, but at full volume I'd be 86'd in a second and my bar let's us play LOUD, but this thing is ridiculous.

So, what am I doing wrong that I can't get decent full sounding tone at a lower volume with the EPA???!!!? I mean it's seriously useless. I'm better off lowering the volume and using a pedal in front to get the distortion I want, but that completely defeats the purpose of this amp. What am I doing wrong?

Try running the auto bias. I'm pretty sure the manual says to run it everytime you plug into a different outlet. It may be over kill, but I run my auto bias everytime I power up. As Redstone said, bump up your channel 2 volume if its a bit thin. I run mine with channel 1 volume at halfway and channel 2 at around 8. I keep the presence at zero and I max the mids. I adjust the treble and bass to taste depending on where I set my EPA. when I'm at home by myself I run the EPA at around 10-10:30. When I'm with the band I run it around 11-11:30. I also run it at 100w mode. I don't use the built in boost at all. I have a clean boost pedal that I use instead.

 

[dash8311]

Try running the auto bias. I'm pretty sure the manual says to run it everytime you plug into a different outlet. It may be over kill, but I run my auto bias everytime I power up. As Redstone said, bump up your channel 2 volume if its a bit thin. I run mine with channel 1 volume at halfway and channel 2 at around 8. I keep the presence at zero and I max the mids. I adjust the treble and bass to taste depending on where I set my EPA. when I'm at home by myself I run the EPA at around 10-10:30. When I'm with the band I run it around 11-11:30. I also run it at 100w mode. I don't use the built in boost at all. I have a clean boost pedal that I use instead.

That's overkill.

 

[JimiRules]

That's overkill.

Even if you unplug the amp everytime you power it down?

 

[srvyjm]

Problems all sorted out after running the auto-bias. I noticed the trim pot was at about 10:00-11:00 on the dial so I turned that up a smidge to 1:00 or so, ran the auto-bias and viola~! The bass is there and the EPA is doing what it was intended to do. I'm now very happy with the first few minutes of play! With the EPA at max-reduction I do indeed still get pretty much the same "tone" as it is at high settings and it's now keeping the bass thump (reduced, but still pleasant) and doesn't sound thin at all any more, and that's without engaging the booster.

Thanks guys, I would have never tried that- thinking that the bias was there just to re-bias the amp when I replaced a bad tube, not to actually modify the tone so much in general, but I guess if it was biased cold it would by default be magnified quite a bit as the EPA was dialed back, making it thin and fizzy sounding instead of the classic Marshall roar.

Now I get to try this beast out on gigs because it's got a real nice sweet-spot around noon-2:00 that won't piss my whole band or the venue off, as well as play it with the kids and wife asleep upstairs! Yeah baby!

I have to point out that now that it has been re-biased and the overall Ma turned up hotter it really changes the entire character of the tone. Holy $h1t this thing ROARS! And the tone is what everyone has been praising from a plexi all these years. WOW!

On a side note, on another Marshall forum (*****************) Santiago himself posted some EPA tips that they put up as a sticky. Worth checking out. Way to go Santiago for actually being on these forums and helping answer questions on your amp! THAT ROCKS!

 

[dash8311]

Even if you unplug the amp everytime you power it down?

Yes... and why would you do that?

 

[AllenCollinsExplorer]

Problems all sorted out after running the auto-bias. I noticed the trim pot was at about 10:00-11:00 on the dial so I turned that up a smidge to 1:00 or so, ran the auto-bias and viola~! The bass is there and the EPA is doing what it was intended to do. I'm now very happy with the first few minutes of play! With the EPA at max-reduction I do indeed still get pretty much the same "tone" as it is at high settings and it's now keeping the bass thump (reduced, but still pleasant) and doesn't sound thin at all any more, and that's without engaging the booster.

Thanks guys, I would have never tried that- thinking that the bias was there just to re-bias the amp when I replaced a bad tube, not to actually modify the tone so much in general, but I guess if it was biased cold it would by default be magnified quite a bit as the EPA was dialed back, making it thin and fizzy sounding instead of the classic Marshall roar.

Now I get to try this beast out on gigs because it's got a real nice sweet-spot around noon-2:00 that won't piss my whole band or the venue off, as well as play it with the kids and wife asleep upstairs! Yeah baby!

I have to point out that now that it has been re-biased and the overall Ma turned up hotter it really changes the entire character of the tone. Holy $h1t this thing ROARS! And the tone is what everyone has been praising from a plexi all these years. WOW!

On a side note, on another Marshall forum (*****************) Santiago himself posted some EPA tips that they put up as a sticky. Worth checking out. Way to go Santiago for actually being on these forums and helping answer questions on your amp! THAT ROCKS!

Glad, you got it all sorted out by now. The autobias solves 99% of the problems you can actually have with this amp. I never actually had a single one, but If I should get one sometime (which is hopefully not gonna happen), the autobias will be my first bet. Enjoy the tone, but I warn you: It's extremely addicting and you won't even think about using any of your other amps anytime soon!

 

[Redstone]

Problems all sorted out after running the auto-bias. I noticed the trim pot was at about 10:00-11:00 on the dial so I turned that up a smidge to 1:00 or so, ran the auto-bias and viola~! The bass is there and the EPA is doing what it was intended to do. I'm now very happy with the first few minutes of play! With the EPA at max-reduction I do indeed still get pretty much the same "tone" as it is at high settings and it's now keeping the bass thump (reduced, but still pleasant) and doesn't sound thin at all any more, and that's without engaging the booster.

Thanks guys, I would have never tried that- thinking that the bias was there just to re-bias the amp when I replaced a bad tube, not to actually modify the tone so much in general, but I guess if it was biased cold it would by default be magnified quite a bit as the EPA was dialed back, making it thin and fizzy sounding instead of the classic Marshall roar.

Now I get to try this beast out on gigs because it's got a real nice sweet-spot around noon-2:00 that won't piss my whole band or the venue off, as well as play it with the kids and wife asleep upstairs! Yeah baby!

I have to point out that now that it has been re-biased and the overall Ma turned up hotter it really changes the entire character of the tone. Holy $h1t this thing ROARS! And the tone is what everyone has been praising from a plexi all these years. WOW!

On a side note, on another Marshall forum (*****************) Santiago himself posted some EPA tips that they put up as a sticky. Worth checking out. Way to go Santiago for actually being on these forums and helping answer questions on your amp! THAT ROCKS!

Glad it worked! The autobias seems to fix most of the problems that people have had with their YJMs. Any time I think something might be up with my YJM, I run the autobias before anything else. It is a feature that Marshall should implement in all amps.

Santiago is great for going on forums and answering people questions. He was around here for a while some time ago. His user name is Santiall, just in case you come across posts from him. I don't think he has been around for a while.

Enjoy your YJM!

 

[AllenCollinsExplorer]

I felt like recording today, so that's exactly what I did. I covered one of my favorite tunes: Ain't No Love In The Heart Of The City by Whitesnake! I used my stock Gibson Les Paul Junior through my YJM and I was (as always with the YJM) very impressed how close it sounded. Back then, Whitesnake used Plexis too and you can totally hear that! I use the amp without the boost, but added some of the built-in reverb. You can check it out right here, if you want to!

[ame=http://www.youtube.com/watch?v=N0eD3V95OSQ&feature=c4-overview&list=UUdizxKB7y5WuvggVcSaT6uQ]Whitesnake - Ain't No Love In The Heart Of The City - Cover - YouTube[/ame]

Cheers!

 

[Redstone]

Nice ACE! Sounded great! You've given me GAS for a Les Paul Jr now

 

[AllenCollinsExplorer]

Thank you, man! I think this video also answers the question, which has been asked too often "how do I get cleans out of this amp?" nicely. You should totally get a Les Paul Junior, they sound incredible and are yet so simple. They kinda look like a one trick pony, but I can almost get any sound out of there like you wouldn't believe. It's just a straight up Rock N' Roll machine!

 

[Redstone]

I've got my eye out for one. I've got my eye out for an SG version too. The SG shape feels more comfortable to me. I wouldn't mind a double cut away version of a les paul in red. I really like those.

 

[JimiRules]

Yes... and why would you do that?

Just a habit I guess. I plug the power chord into a power strip and plug that into the wall. When I'm finished playing I unplug the power strip from the wall.

 

[dash8311]

Ah okay. I have a power bar as well, one side is switched, one side always powered. My amp is plugged into an always-powered socket, while my tuner and wireless on the switched.

 

[Redstone]

I'm thinking that I might have to get into the habit of plugging my YJM out from the wall after use. Lightning struck a few feel away from my house today. The thunder was one of the loudest bangs I've ever heard. I'm just glad it didn't hit. It scared the crap out of my dog. Poor guy came running up to me and was shaking. I don't think he has ever heard thunder before, especially not that loud.

 

[dash8311]

The major power bars/conditioners have surge protection.

Has anybody ever had an issue with surging?

 

[JimiRules]

My band got together today and we recorded a few quick covers to send out to various venues in our area. Here's our take on Rock and Roll by the mighty Zeppelin! I used my SG Standard through my YJM which is boosted by my Bad Bob Boost.

[SC]https://soundcloud.com/alternateendingbandtiffin/rock-and-roll[/SC]

 

[AllenCollinsExplorer]

Sounds great, Jimi! You totally nailed Page's tone!

 

[Redstone]

That sounds awesome! What were your settings?