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-   -   Questions about Champ mods, NF loop and more (http://www.diyaudio.com/forums/tubes-valves/227292-questions-about-champ-mods-nf-loop-more.html)

eugene martone 8th January 2013 08:11 AM

Questions about Champ mods, NF loop and more
 
Hi everybody (it's Dr Nick :p)
Going to build a champ, and as I've already played a few of those, I want to make a few changes (even before the build, cos when I've got it working I'm not going to change anything for a while)

Using the 5f1 schematic I'll try to make the overdrive a bit smoother/ more marshally (read jtm45). I'll add a cathode bypass cap on the first gain stage, either a 47 or a 25 mF cap, keeping the 1,5k resistor. Next i thought about changing the cathode resistor of the second stage to 820 ohm to run it a bit harder. Then I thought of using sozo mustard coupling caps making the first .022 and the second .01???

Any other tips would be appreciated. Or if you think any of mine are counterproductive.

Now to the most important question: Negative Feedback?
I've seen a lot of people remove the NF loop, but it sort of takes the amp the opposit way of where I want it (Yes it breaks up earlier, but sounds even less smooth).
I'll be using a bigger OT with 4 8 and 16 ohm taps and was contemplating taking the NF from the 16 ohm one (like Marshall did on the JTM). Any one try this, or anyone smart enough to predict how this might work? Should I just lower the value of the NF resistor? Just leave it alone?:confused:

PS I'll put a g12m in an oversized cab for this so that should take me closer to the marshall sound.

PPS I know it'll still be a champ and I wouldn't want it to be anything else, but just want the od to resemble early marshall a little more...

DF96 8th January 2013 09:15 AM

Should be in Instruments & Amps forum?

eugene martone 8th January 2013 09:31 AM

Ah sorry, how can I change this? Moderator help!

eugene martone 8th January 2013 10:10 AM

I'll repost in Inst. amps, so please someone delete this thread.

DF96 8th January 2013 10:27 AM

Don't repost. Click the 'report this post' button (lower left in red triangle) and ask for a move.

wintermute 8th January 2013 10:32 AM

too late he has started another one ;) http://www.diyaudio.com/forums/instr...loop-more.html I'll close this one.

Tony.


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