Re: Marshall JCM900 MkIII Info
I've been doing some more research on the MkIII amps the last couple days and even though I haven't come across anything new, I have come across a few places that have described these amps very wrongly or inconsistantly, both the MkIII and SL-X.
Here's what I found with my response below:
1. The MkIII Master Volumes and SL-X share the same pre-amp as the Dual Reverbs.
- FALSE. This is so false it's not funny. The schematics are nowhere near being close. Very different preamps.
2. There are 3 tubes in the pre-amp (4 in the SL-X)
- Much to everyone's dis-belief, this is false. There are really only 2 tubes in the pre-amp of the MkIII, 3 in the SL-X. The 3rd tube in the MkIII and 4th in the SL-X are the phase inverter, which is actually after the pre-amp and right at the beginning of the power amp section.
3. The MkIII sounds thin.
- Now this one is just silly. Many times people forget that thinness doesn't necessary come 100% from the amp. The speakers, the type of enclosure (open or closed back), the guitar, pickups, all of these things come in to play so to whether the amp sounds thin or not. Tell ya what, mine sounds anything but thin.
4. This one is clarification on my part in case I've told anyone else wrongly. I apologize now. The SL-X does have an all-tube pre-amp. There are no diodes that I can see on the schematic. However, acquiring one with EL34's is best if you want one.