Fourth preamp tube

[rockstah]

Pretty freakin' sweet!

[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

btw this is only using 3 tubes.
Mark

[joshwilson3]

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

Yeah, if I added a 4th preamp tube for an extra gain stage to a 2203. I'd still want to be able to switch between a stock 2203 and the extra gain stage. I think some guys use the inputs. One input has the extra gain stage, the other input is the high input/stock 2203. That probably would be a cleaner looking install. But I might would want an on/off extra gain stage switch so you can retain the low input of a stock 2203.

[LP Freak]

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

btw this is only using 3 tubes.
Mark

That sounds great Mark.

[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

btw this is only using 3 tubes.
Mark

That sounds great Mark.

thanks!
Mark

[MVDW]

This is pretty much what I did in my build.
http://forum.metroamp.com/viewtopic.php?f=7&t=34552" onclick="window.open(this.href);return false;

A four tube preamp that is switchable between all stock 2204 and hotrod mode. I just have 1 input jack. And the added gainstage is switchable with a toggle on the front or a footswitch jack on the back. Only thing is that switching gives quite a noticable pop with high gain levels.

I definately like all the extra gain, and it sounds Marshall all the way.

[joshwilson3]

Has anyone tried the Soldano Hot Mod? It's an adaptor for the 2nd tube slot that adds an extra gain stage. So, I'd assume it would be similar to adding an extra tube.

[Kapo_Polenton]

Guys, bringing this thread back from the dead.

It is a great and very helpful thread but falls short because it has a suggested "outline" layout that SDM put together but no idea on which values to tweak to tame the bass/mush. How about re-opening this discussion and hearing some suggestions on how to tame the wildness in that layout? (and of course a big thanks to SDM for the resource and throwing it together even if it just was meant as a baseline idea/guide)

As for the soldano hotmod.. I had one and wasn't that sold on it. I still boosted to tighten the gain. I ended up just slightly tweaking my 800 to get the gain i wanted out of 3 stages and it sounded better than the hot mod. As I am now doing another build, I want to try a 4th preamp tube for $hits and giggles so i am looking at this again.The bainzy mod uses two .68y /2.7k off the new half V1 and V2 and the sound clip from that is pretty solid. This combo has also been recommended to me elsewhere by a builder so that might be something people want to try. Discuss!

[ezs]

Looking at this again a couple years later, now I see .47 /10k is boosting 34hz, try .1there. Read Rk Ck thread. The voltage divider 68k/220k may be it too. Try flipping 220/68k to gnd. Just from a glance. This layout will fit the Langner schematic floating around perfectly.

[erigm]

Looking at this again a couple years later, now I see .47 /10k is boosting 34hz, try .1there. Read Rk Ck thread. The voltage divider 68k/220k may be it too. Try flipping 220/68k to gnd. Just from a glance. This layout will fit the Langner schematic floating around perfectly.

By changing the .47uf to .1uf you're getting pretty close to the roccoforte spec that Rockstah posted a clip to earlier in the thread. This may have been pointed out earlier, but just thought I'd mention it. I've tried .22uf there with good results as well.

Is the Langner schematic the one with three 4.7uf cathode bypass caps on the first three stages? If so, I've read that these should actually be .47uf (470nf), which would make sense, otherwise it could get flubby as well.

[ezs]

Yes thats the one I was talking about. Was going to try with .68. I have 2 amps with this board layout which get messed with all the time, Egnater used this topology as well w/Modzilla I think.

[erigm]

Yeah, modzilla would be easy to stuff in there. Another good circuit was Crate's lead channel for their VC3112 vintage club 30 amp. Also if we move the preamp pot to between the first and second stage of course we open up an even huger can of worms. Bogner, CAE, Caswell, 5150III blue channel, etc. Fun stuff, and it's hard to know when to stop modding!