YJM100 - 'The Ultimate Plexi' thread!

[Holme]

I do have a couple of questions for the other owners.

1. When I power down, even with the standby switch engaged for a few minutes, when I turn off the power the sound comes back on really loud before it shuts off. Is this normal? Shouldn't it be quiet and just turn off? Maybe it has something to do with the EPA and the volumes on front being up?

2. I turn the amp off with the boost and reverb engaged. When I turn it back on they are no longer active and I have to turn them on. Shouldn't it remember to leave them on? Is this normal, does everyone's do this?

Hi indeedido

1.When I power down its usually boost off,standby,volumes 0 & finally power & it's silent.Saying that though I don't usually have the EPA above a 1/3rd at home so may be different at that volume?

2.When you turn the amp off it won't turn back on with boost,reverb OR 50 watt mode still engaged.
This is normal!

 

[indeedido]

Thanks Holme! I was beginning to wonder. So glad to hear all is well with it. I went with the factory refurb for $1650 including shipping and got all the goodies with it including the build sheet or whatever you call it with all the peoples signatures along the way for quality inspections and such. It's essentially brand new with no signs of use whatsoever for a fraction of the price.

 

[John 14:6]

My YJM100 came stock with a Marshall red labeled JJ 12AX7 in the V1 first gain stage and Marshall white labeled Shuguangs in V2, V3, and V4. The stock power tubes are SED Winged C EL34's. Well, today I replaced the V2 second gain stage with another JJ 12AX7 and the amp sounds even better and warmer. Some of the over the top high end was warmed up and the boosted and non boosted signals are now more balanced. Stepping on the boost does not add as much high end to the signal as with the Shuguang in the V2 slot. Installing the Chinese Shuguangs are an easy way to add gain to an amp, but the JJ's have plenty of gain and a lot more warmth too. My great amp just got even better.

 

[66 galaxie]

Suggestion noted....

 

[John 14:6]

Suggestion noted....

Sorry, but I meant to say that stepping on the boost does NOT add as much high end to the signal now with the JJ's in V1 and V2. I edited my previous post to make the correction. I was typing too quick last time and left out the word "not" which made my statement say the complete opposite of what I had intended to convey in my post.

 

[66 galaxie]

I guess thats the way I read it anyway
That's cool though, I got all kinds of preamp tube options courtesy of RiverRat

 

[Holme]

Thanks Holme! I was beginning to wonder. So glad to hear all is well with it. I went with the factory refurb for $1650 including shipping and got all the goodies with it including the build sheet or whatever you call it with all the peoples signatures along the way for quality inspections and such. It's essentially brand new with no signs of use whatsoever for a fraction of the price.

Sounds like you got a fantastic deal to me & looking at your pics I thought it was brand new!
Cool amp at a cool price!
What more could you ask for!
....& with all that money you saved you can stock up on doughnuts!

 

[Holme]

My YJM100 came stock with a Marshall red labeled JJ 12AX7 in the V1 first gain stage and Marshall white labeled Shuguangs in V2, V3, and V4. The stock power tubes are SED Winged C EL34's. Well, today I replaced the V2 second gain stage with another JJ 12AX7 and the amp sounds even better and warmer. Some of the over the top high end was warmed up and the boosted and non boosted signals are now more balanced. Stepping on the boost does not add as much high end to the signal as with the Shuguang in the V2 slot. Installing the Chinese Shuguangs are an easy way to add gain to an amp, but the JJ's have plenty of gain and a lot more warmth too. My great amp just got even better.

Interesting!
One thing I haven't done is change any valves so I'm all ears at people's findings!
Glad you're enjoying your new sound & your experimentation has been duly noted!

 

[pleximaster]

Changing the tubes is like fine tuning an amp to fit you and your guitar and speakers, getting a bit more bit, changing gain rolling off the top end sand stuff, not huge variations but more subtle but important tone changes. Going from good to great.

I played arround with the powertubes the other day putting in old sets of Mullards and Maztas they sounded great at high volume, but using the EPA a lot a set of electro hormonix sounded the best.

The preamp
I put in a old mullard i the first slot and and some RCA in the rest of the slots. The Mullard stays but the stock tubes returned in the other.

Have fun and play around with the tubes you have. The self biasing is great for testing out power tubes.

I don´t know if this is ture but I feel that using the self biasing feature you should set the epa at the volume you plan to use. If you going for bedroom volume run the bias thing with the EPA at all the way down and if you want more volume like the EPA arround noon set that valvue befor running the self biasing.

plexi

 

[Holme]

Thanks for tips plexi master!
I'm using mine with quite a lot of EPA so electro harmonix might be the best for me?

 

[Australian]

I don´t know if this is ture but I feel that using the self biasing feature you should set the epa at the volume you plan to use. If you going for bedroom volume run the bias thing with the EPA at all the way down and if you want more volume like the EPA arround noon set that valvue befor running the self biasing.

plexi

Thats interesting and new. What led you to this idea?

 

[pleximaster]

Things like this is always hard to put finger on. But as I said I don´t know if its true or not or if its only in my head. Comparing sound before and after you do the biasing thing is tuff since it take a minute or two. Hard to A/B…

I guess it can be true since the EPA trimpot it self must involve self biasing circuitry and the self biasing procedure sets a reference point for the EPA to work from. Hopefully Santiago, Steve D or James M can chime in and set me straight! J

Best regards plexi

 

[Söulcaster]

Things like this is always hard to put finger on. But as I said I don´t know if its true or not or if its only in my head. Comparing sound before and after you do the biasing thing is tuff since it take a minute or two. Hard to A/B…

I guess it can be true since the EPA trimpot it self must involve self biasing circuitry and the self biasing procedure sets a reference point for the EPA to work from. Hopefully Santiago, Steve D or James M can chime in and set me straight! J

Best regards plexi

hmmmmm, I don't know about that Plexi..., it's just something I've never considered doing. I thought the EPA and self bias are seperate entities, so it should make no difference what level the EPA is on when you self bias....?

I'll keep watching this space to see what develops from this....

Peace

 

[John 14:6]

Changing the tubes is like fine tuning an amp to fit you and your guitar and speakers, getting a bit more bit, changing gain rolling off the top end sand stuff, not huge variations but more subtle but important tone changes. Going from good to great.

I played arround with the powertubes the other day putting in old sets of Mullards and Maztas they sounded great at high volume, but using the EPA a lot a set of electro hormonix sounded the best.

The preamp
I put in a old mullard i the first slot and and some RCA in the rest of the slots. The Mullard stays but the stock tubes returned in the other.

Have fun and play around with the tubes you have. The self biasing is great for testing out power tubes.

I don´t know if this is ture but I feel that using the self biasing feature you should set the epa at the volume you plan to use. If you going for bedroom volume run the bias thing with the EPA at all the way down and if you want more volume like the EPA arround noon set that valvue befor running the self biasing.

plexi

I was told to set every knob on zero
back when I first learned to bias my Splawn Quickrod. The amp was supposed to be kind of set on "idle" during the bias adjustment. I do know that some people play while biasing and set it by ear.

 

[olirc7usa]

Hello, i just received my YJM100 .... i love it, it sounds awesome !

the only negative point is that there's no midi possibilities for channel switching (like the 30th anniv., or jvm) ... i have a ground control pro, and a midi multi fx... but you always need the traditionnal marshall footswich for swapping the channels clean/boost...

* anybody as tested a midi channel switcher on a YJM 100 ? (voodoo lab switcher or gcx, gizmo, etc... ?)

* i wonder how a relay switcher will work with the yjm : the original footswitch is a simple mono jack to activate 4 differents fonctions (boost, gate, rvb, fx) ??

 

[indeedido]

When doing the autobias, is the amp still in standby mode or when you hold the two buttons down and power up should the standby already be on?

 

[mAx___]

I'd like to introduce a sub-topic of conversation. Have any of you thought of upgrading the amp to better components yet? Anybody did it already? Results? Can't help thinking what a set of Sozos and/or new transformers could do for this amp...

 

[Will55555]

When doing the autobias, is the amp still in standby mode or when you hold the two buttons down and power up should the standby already be on?

If I understand what you are saying then

I leave both the master and standby switches off then whilst holding in the 2 buttons at the back just turn on the master and it starts biasing.
Once the lights start flashing it's doing what it should be doing.

Why would you leave the standby switch on before you turn on the master?
You need to warm up the valves before you turn on the standby!

The only time I would bias it is when I plug into a different wall socket. I don't think you need to do it too often.

Hope that helps man!

 

[slagg]

Can somebody do some clips of this thing cranked??Un-attenuated.

 

[Will55555]

Can somebody do some clips of this thing cranked??Un-attenuated.

I wish I could man. It's fucking loud as hell though. I ain't got the best place to try that around here. Maybe one of the owners here lives in a nice rural area where they can crank it, wish I did.

There is however a clip on utube of some guys trying it against an AFD to see which is loudest so there is no attenuation on it in that video.

[ame]http://www.youtube.com/watch?v=PMh0tUDGbck[/ame]