2204 or Hot Switch

[macula56]

which type of overdrive sound do you prefer? the stock Marshall 2204 type or Doug's Plexi with the Hot switch? thanks, Jmac

[rzenc]

Hot Switch.

[topbrent]

What is the difference in sound overall?

[rzenc]

The difference between them goes a bit far from different cathode resistors. JCM800 2203 also uses many high pass filters which can make it very earpiercing – at least to me. Hotswitch does not use them at all, so the resulting sound is “rounder”, less trebly or full bodied if you wish… it sounds bluesier – if I can say so – and depending on guitar connected, it can become a real war machine.
Even though Hotswitch does not fit high pass filters on the preamp, all notes are very well defined and clear, it is perfectly possible to hear every single note. Sustain is very very nice…

check out the schems:
http://www.el34world.com/charts/Schematics/Marshall_JCM_800_LEAD.pdf
http://www.el34world.com/projects/hotswitch.htm

There are at least 4 treble peaking circuits on 2203 while HS uses none. V1b cathode resistor on 2203 is 10K, HS uses 2K2.
V2a cathode is unbypassed on 2203 while HS partialy bypasses it with .68uF - lots of difference on this one!!!!

Both circuits uses ECC83 as V1, but I do like 12AY7 with hotswitch better then ECC83.

Just my 0.02

Hope this helps
Best Regards
Rzenc