Fourth preamp tube

[SDM]

That layout came about when years ago some simply asked how an extra stage could be added to the front end of a 2203 amp in general. So it started as just a rather "generic" extra stage up front on a stock 2203 which he was then going to tweak to his liking.

As I recall he did just that, tweaked things to his liking and the layout reflects his changes, at least at some point. So just decided to throw the layout up on the site years ago, unclassified and with no descriptions, for the heck of it. Still only really meant as a general base for how a stage could be physically added to the front end for those that happened to stumble across it. Tweak as desired, take and leave bits as desired.

So anyway, it's not something I have ever built, just a layout I helped someone with years ago. Thought the base layout and some things in there could be of use to others for ideas, so decided to throw it on the site somewhere.

[LP Freak]

As far as dialing in my own values, I'm new to this so I was looking for some help. I was wanting to experiment a little with the tone of the amp but I don't know my way around the board too well yet. Can you give me some advice on what to change and what to change them to?

[RagnarMarGunn]

LP freak,

I used SMD´s layout to add an extra tube to my Metro 50W kit which I had converted from 1987 to 2204 (also SDM´s layout) and it´s simply great, at least to my ears. Did some clips:
http://soundclick.com/share?songid=8318163

[LP Freak]

Wow, impressive!

[Kramer]

That's a great cover right there

[joepete]

I had a 77 2203 modded with the extra tube and 2nd master volume and it was one of the best sounding Marshalls I have ever owned! IT was a bit noisy when the gain was cranked high but other then that it sounded awesome. I will try to find the layout 4 u

[trubasser6778]

Hey guys, I'm a complete newbie to all of this. I'm going to be building my first kit this spring and was looking to maybe add a 4th pre-amp tube myself. What I really wanted to be able to do is put in a second pre-amp gain control and a switch to be able to have essentially two channels one being the stock 2203 and one with the added gain stage each with their own gain control. Would this be possible or am I all wet?
Thanks,
Kyle

[niksa]

Hello guys I've just found this great forum.
I have question about this mod. When using 6550s after changing 3 resistors to another value, do I also need to connect negative feedback wire (with 1.5nF capacitor) to 4 ohm tap? It seems logical for me to do this. Thanks

[Roe]

changing nfb with 6550s isn't necessary but it gives a tad more breakup and warmth

[jerrydyer]

that Landry sounds great.

[erigm]

LP freak,

I used SMD´s layout to add an extra tube to my Metro 50W kit which I had converted from 1987 to 2204 (also SDM´s layout) and it´s simply great, at least to my ears. Did some clips:
http://soundclick.com/share?songid=8318163

Just to clarify the layout that Ragnar used is different than the one posted earlier in this thread. The one posted earlier adds the gain stage in front of the standard 2204 circuit.

[fusionbear]

Any reason you can't parallel the added gain stage tube? Hate to leave that other triode unused...

[joshwilson3]

What about adding an extra gain stage like whats on the Soldano Slo?

[rockstah]

here is the clip i did with the rocco mod.
http://www.soundclick.com/bands/page_so ... ID=3877112" onclick="window.open(this.href);return false;
Mark

[MaximumGtr]

Pretty freakin' sweet!