#1
I want to put a new speaker in my Marshall 6101 combo. It currently has the original Celestion Gold speaker in it, but I'm beginning to hate the sound of it. The amp sounds great through my 4x12 cab, but I don't have room to set it up to practice through.
The original sounds thin & a bit nasty, probably because it's open back & my 4x12 is closed back, but I've spent several hours in the last week trying to EQ it better, but no luck so far.
I'm in the UK, so I've been looking at the Celestion G12K 100 & the G12H 150 Redback, which I think is a new speaker. As the amp is a 100 watter, I don't want to risk putting a smaller speaker in it, even though I don't usually go past about 3/10 on the master, although it's fun to sometimes annoy the neighbours!!   
There is not enough difference in price to make one more attractive over the other, so any input on these please  

Thanks in advance
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#2
Since the amp is 100w and only has room for one speaker, your options are limited. The best I can see from Celestion are the ones you have listed. The G12k and Redback. Marshall typically likes Greenbacks, not sure why they put an Alnico Gold in there (that can handle 200w from what I see).

I think a part of your sound problem is related to the Gold's difference between the Ceramics, but another part- and why you like the 4x12 better- is the 1x12 nature of the amp housing. Really, I'd prefer a 2x12 at least but that is just me. Another option is to see if you can drop the output wattage by pulling two of the power tubes and adjusting the output impedance. That would get you a maximum output of 50w which can open your doors to some other speakers as well, and it would drop your overall volume. However I am not sure you can do that safely with your amp, someone else would need to chime in.
#3
Quote by Will Lane

 Another option is to see if you can drop the output wattage by pulling two of the power tubes and adjusting the output impedance. That would get you a maximum output of 50w which can open your doors to some other speakers as well, and it would drop your overall volume. However I am not sure you can do that safely with your amp, someone else would need to chime in.

There are 2 switches on the back to drop the power down to (allegedly) 25 watts. One takes 2 power valves out of the equation (half power), the other changes from pentode to triode operation. The first does make a noticable difference, the second....... not sure it does anything, oh well!

The half power only diverts the signal from 2 valves, but they are still powered up, so if I'm wearing them out anyway, I might as well still use them.

As far as gigs go, I use my 4x12 cab with my Randall RM100, but for practice at home or else where I usually use the Marshall, less to lug about. 

I was wondering if the 2 speakers I listed would be better with an open back cabinet than the one in the amp already.
My Gear:- A guitar, a guitar lead, a guitar amplifier. Or sometimes just an acoustic guitar!
#4
the redback's very new, but what little i've heard about it (online, i mean, i haven't tried it) has been pretty good- people seem to be rating it highly. there was a thread on the fretboard forum recently about it i think if you want to do a google search.
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