86 Marshall 2210 which preamp

[Guitar-Sam]

I have heard that there were many changes between the 1983 and 1987 schematics. And that pre 87 heads may have the 87 circuit or a predecessor version.Now I've heard that if you pull v2 out on a 87 circuit the boost channel will still work?Has anyone tried it on both circuits? My 86 the boost still works with no v2 but has a faint drop in gain.Also the amp works with no v4 in place. I dunno?? Any help/info would be appreciated. Sam S

 

[mickeydg5]

Pulling V2 in the original version will affect the BOOST while pulling V2 in the two later versions will affect the NORMAL channel. You may hear a faint signal through the other channel after pulling the tube.

Pulling V4 indicates which version you have of the two later versions. Yours is the first of those two, the second or middle version since pulling V4 only affects the REVERB circuit like the original version.

 

[RickyLee]

I would like to know why they split the reverb up between two valves V3 & V4. I always thought it would be better to have V3 as two gain stages for Boost only.

But then you can argue that having that last design will allow you to have two different brands of 12AX7 for those two gain stages split between V3 V4. So as to be able to tone shape and tweak on it.

 

[Guitar-Sam]

Is there a schematic to the middle version preamp available? Weird cause mine seems to have v2 as the clean stages like the 87 circuit but not the shared v3v4 reverb.makes me wonder if it has the tone stack after the first gain stage or later like 87. Not that it really matters tonewise as I love this head either way. These mid year changes etc... Are prolly why I hear such mixed opinion on the 2210s,no??

 

[mickeydg5]

The only one I have seen.
http://el34world.com/charts/Schematics/files/marshall/Marshall_REVERB_2205-2810-4210.pdf

 

[RickyLee]

Is there a schematic to the middle version preamp available? Weird cause mine seems to have v2 as the clean stages like the 87 circuit but not the shared v3v4 reverb.makes me wonder if it has the tone stack after the first gain stage or later like 87. Not that it really matters tonewise as I love this head either way. These mid year changes etc... Are prolly why I hear such mixed opinion on the 2210s,no??

I am sure you would have the later preamp design with the tone stack after the first three stages (Boost).

Bummer as the schem Mickey posted could have some component values varied but can't make out most of them. The layout is the same except for the V3 V4 assignments.

What model was 2810? Never seen one.

 

[mickeydg5]

I believe the 2810 was a typing error for 2210.

 

[Guitar-Sam]

Thanks for the help guys. Yea it's hard to read component values but it looks like same circuit but reverb on different triodes.

 

[Guitar-Sam]

Weird if they are pretty much the same circuit,basically wouldn't swapping the wires around on v3b and v4 achieve the same thing.....not that I'm gonna do that I already got my 12ax7 cocktail figured out for this amp

 

[Procter2812]

Iv got an August 86 Model, i don't have any channel spill which I'm guessing is the revised circuit, however the reverb is pretty noisy, ended up changing either V3/4 for an ECC81 to tame it..

 

[Guitar-Sam]

Mine had a hum problem and the reverb wasn't working. Turned out to be a dirty v3 socket. Mine bleeds a little if you make drastic changes to the normal it will slightly effect the boost channels tone,but it is very slight. When I dial up the amp I adjust mainly for the boost but at the same time try to keep the normal still "usable".personally I'm not impressed with the normal side