Marshall 4104 Jcm 800

lespaulcustom68

Any difference in vertical and horizontal input models. I know about the 2203 100w circuit differences, but are the combos a different story?

rico

I'm lead to believe the difference is in the clipping stage - vertical is valve clipping and horizontal is diode clipping. 

ICBM

rico said:

I'm lead to believe the difference is in the clipping stage - vertical is valve clipping and horizontal is diode clipping. 

Not at all. There is no diode clipping in any JCM800 single-channel amp.

The 50W models are the same circuit whether they're vertical or horizontal input - it's only the 100s which changed.

rico

That's me schooled!

ICBM

Sorry, that reads back a little blunt now .

It's interesting how myths like this take hold though!

There certainly is diode clipping in the JCM800 Split-Channel amps - although interestingly there are three different circuit revisions of these, the first one of which is very different to the second two (and corresponds to the vertical-input MV models in date), but because there's no obvious visible difference from the outside like the vertical/horizontal inputs, fewer people seem aware of it… but the difference is much more important, if you like those amps. The difference is both in the preamp circuit (which really is almost totally different, apart from the control layout) and the power supply filtering, which is the same as the difference between the vertical and horizontal-input 100W MV models.

The other ironic thing is that despite the bad reputation diode clipping has, one of Marshall's most rated amps, the Jubilee, uses it...

Modulus_Amps

Vertical inputs are more sought after, the circuits are the same, but the main difference being that the pots and input jacks are mounted directly to the circuit board on the horizontal inputs and the vertical one uses flying leads.

The flying leads make it easier to change out single components without lifting the board. Also if you wanted to try any mods the vertical input version may be easier to work on

This is the vertical input version


This is an example of the horizontal inputs versions


Schematics are all online if you want to check them out

lespaulcustom68

How does £450 sound for one in good nick?

ICBM

Sounds about right - I think we sold the last one I saw in the shop for £499, although it might have been £449… can't remember, but it was over a year ago.