Marshall 30th Anniversary Series thread (6100 / 6101)

[Mentalo]

With standby on ( no sound) measure the voltage swing on pin 5 ( green wire) while rotating the bias pot fuly ccw/cw. Now clip one end of the zener and lift it up a bit so it's positively disconnected and measure again, what is the difference?

It’s -33 to -48V in both cases. The clipped Zener also doesn’t seems to have an effect on the idle current it’s still @ around 52mA even with the clipped diode and the trim Poti fully closed.

Now I‘m really confused cause I read trough all the topics regarding the 6100LM and the zener diode and in all cases it seemed to help…

 

[Thoma]

Have you checked the current instead?
Even though Marshall refers to bias voltage, I always prefer to check for HT voltage and current to set the power.

 

[Mentalo]

Don’t now if I misunderstood you, but thats what I did. Plate Voltage x idle Current was my initial measurement

 

[Thoma]

I was referring to the current range (corresponding to the bias voltage).
You can't get lower than 52 mA, right?

 

[Mentalo]

I was referring to the current range (corresponding to the bias voltage).
You can't get lower than 52 mA, right?

Correct

 

[Thoma]

Have you tried another quad (or pair) of 5881 In the LM?
I remember that I had one set of these Russian 6П3С-Е tubes that was particularly hot.

 

[Mentalo]

No unfortunately not, the ones that came with it had one broken. I think I will get a quad of JJs 5881 but for now I will run the amp this way and keep an eye on it in case of redplating. In the webs the opinions about the 6P3S-E seem to be very different, some seem to operate them around they values that I am at right now.

P.S.
Re-Sticking them into the sockets seemed to scrape of some oxidation which dropped the current for another 5mA to a total of 48mA

 

[Mentalo]

Short update regarding my trouble shooting:
Of course Murphys Law hit again and one of the 4 tubes showed signs of red plating. Fortunately the red plating kept staying with the tube when chaining sockets. So I guess this NOS set is a bit fishy. I then salvaged two of the 4 tubes that came with the amp. Left the outer sockets unloaded. Switched to half power. Bias with those tubes is down to 42mA at lowest. JJs are on their way. Amp runs fine so far:

Marshall6100_Still_Waiting.mp3

Listen to Marshall6100_Still_Waiting.mp3 by Mentalo87 #np on #SoundCloud

on.soundcloud.com

 

[Thoma]

this NOS set is a bit fishy.
I then salvaged two of the 4 tubes
outer sockets unloaded.

Have switched back to 5881s as well.

I am running my Amps w/ 2 inner tubes without any issues for years, even though I prefer the 100W cranked sound of the 6100 through a Power Brake.
But tone is plenty great even with 2 EL34s (or 5881 when I use my LM).

42mA should be OK provided HT is not too high.

 

[Mentalo]

So it really had something to do with the tubes after all. Got the new quad of JJs all set up. Lo and behold now got a bias range from around 30mA up to 55mA. So I could set them up to a comfortable W_diss of around 70% (Plate Voltage at 460V now). Nice side effect: When I got the amp it had a real flubby and fuzzy low end on channel 2 and 3 with gain over noon, almost sounding like a big muff. Now it really shines by it self without the boost of an SD-1 or TS9. I really bonded with the amp, sounds fantastic.... Thanks for your help!

 

[Thoma]

Looks we had similar experience w/ 6П3С-Е tubes.
Yes the 6100LM is a hell of a great sounding amp.
Provided one does some knob twiddling, other then "all to 11".

Enjoy your beast!

 

[Mentalo]

@Thoma seeing that you have a couple of variants of the 6100, does the combo version sound exactly the same as the head (given that its the same iteration), and which one is easier to transport?

I'm already planing ahead to integrate the amp into my live rig, but I'm not in the mood to get it from my apartment to the rehearsal room to the stage and vice versa. So a second one might come in handy at some time...

 

[Thoma]

The 6101 Combo is quite heavy (Guessing about 35-40Kg).
It has the same handles as a 1960 4x12 for good reason.
However the advantage is that there's less room needed for transport.
The 6101 Combo's sound is great, but I would recommend a 6912 Extension Cab for stack like tone.
The circuit of the combo equals its 6100 counterpart.

 

[Seventh Son]

In his review of the 6100, Leon Todd described the Crunch channel as the "Plexi channel," and the Lead channel as the "JCM800 and beyond" channel. What do you guys think? Is that a good way to describe what the two channels do?

 

[Mike_LA]

In his review of the 6100, Leon Todd described the Crunch channel as the "Plexi channel," and the Lead channel as the "JCM800 and beyond" channel. What do you guys think? Is that a good way to describe what the two channels do?

To him it did, to you . . . those and more options.
Sometime I used the red channel more for clean with a little breakup, other times it's the uber OD channel...
the yellow side has 3 different modes, one could be plexi to your ears

 

[Thoma]

Todd's video scratches only some possibilities of the amp.

He calls CONTOUR the suck control. He obviously didn't utilize it properly.
I love it because it gets me in foreign area like MESA and others.
But one has to understand that it changes the tone stack, so you will need to balance it with Presence, Treble and Bass dials.

The beauty of the 6100 is that it has plenty of great sounds at low volume.

I prefer to run channel Volumes quite high and use Master Volume to dial in the desired Volume or - with Powert Brake - desired amount of Power Amp distortion.

And as it's a Marshall 100W head...
Crank it on top of two 4x12"s and enjoy the earthquake!

For some more tone snippets, you want to search YouTube for "segeborn marshall 6100".

 

[Riverside Bluesman]

Newbie here ! Just wanted to say that I've just picked up a nice 6101LM combo and what a great amp it is.

I remember seeing the blue one when they first appeared in the early 90's and just stood staring at this thing in the shop overwhelmed by all the switching. Always wanted one and finally got one at the right price at the right time, albeit thirty years later. £350 here in the UK so I jumped on it.

Doing lots of recording right now, so the DI facility is really useful. Had Boogies for years, but this amp has really impressed me.

 

[rtcook]

Great price. Enjoy!

 

[Thoma]

wanted to say that I've just picked up a nice 6101LM combo

Never underestimate the addiction potential of 6100 series Amps.

 

[Kuga]

Newbie here ! Just wanted to say that I've just picked up a nice 6101LM combo and what a great amp it is.

I remember seeing the blue one when they first appeared in the early 90's and just stood staring at this thing in the shop overwhelmed by all the switching. Always wanted one and finally got one at the right price at the right time, albeit thirty years later. £350 here in the UK so I jumped on it.

Doing lots of recording right now, so the DI facility is really useful. Had Boogies for years, but this amp has really impressed me.

Welcome to the Forum. Really good price congrats on a great Marshall.