Now you’ve done it!!

Looks alright

Well, I’ve been threatening to do this for a long while and I never had the right equipment.  But since my Franken-Baby is done and ready to be delivered, I had to make an attempt no matter how sucky it might turn out.  Actually, it doesn’t suck (too bad) at least.  I used our trusty little Nikon CoolPix camera and recorded a video clip using the on board mic.  that was the reason I thought it was gonna be terrible, but it came out pretty good other than the hiss/background noise is a bit exagerated, at least the mic wasn’t overloaded and distorted.  So without further ado, may I present the “ShowMaster”. . . . . . . . .

Well, without paying for the video upgrade, you’ll have to go to You tube to see it, here’s the link:  (actually it did show up here – cool!)

I’m pretty happy overall with how the amp turned out.  I like the solid sound of the Thick channel, it doesn’t get real gainy or saturated like cascading stages does, but has a lot of authority and is quieter.  I paralleled the first preamp tube, then used a 1uf cathode bypass to tilt the response up.  I originally had a 25uf cap in there, but I felt the bottom was too big.   I mean some people like big bottoms, and while I’m a fan, this needed to be a little sportier. Now as the clip shows, when you dime it, it has that Marshall grind, but never falls apart.  For the tone stack bypass, the switch adds a 750pf cap across the treble cap, which allows more upper mids and a little gain boost.  Nothing too dramatic.  As I say in the video, it adds a little chunk- that’s a technical term meaning an upper mid boost with a little bite.   Also the venerable LaMar Post PI master volume,(as detailed in the forum over at Metropolis amps), was added afterwards at the request of it’s chomping at the bit new owner.  I had to move a few things from where I originally had them to get it in there.  If your frustrated with traditional master circuits, you owe it to your self to try this one.  It’s a refinement of a Ken Fisher design, that keeps the sound of the pre-power relationship intact.  Most masters shut down the per amp signal and the PI/power section doesn’t get hit the same way and you lose all that juicy power amp distortion.

A few other technical details, since I was going to use 6V6’s, I bumped up the screen resistors to 5k@5watts, to protect them from meltdown.  Especially since I’m running a Twin power transformer and it’s putting out 445-450 volts on the plates.  There are a few modern tubes that will handle that much voltage, namely the JJ’s and the new Electro Harmonix 6V6.  While they probably deviate a bit from a traditional 6V6 ala RCA or Sylvania, they have their own unique sound and won’t fold up and die – and you can still get them!

Four Little Piggies All in A Row

The thing I haven’t really talked about is the Vibrato channel, which has that nice sweet Fender Bandmaster sound.  The only issue I’ve run into is that the tremolo isn’t throbby enough for my liking.  All the parts are new, all the voltages are in the ball park and it has a new LDR opto-bug, but it doesn’t start to show up till the Intensity knob is at “10” and then it still is too polite.  I’m not sure if a different roach would make a difference or not.  I’ve heard talk that the modern reproduction LDR’s are spotty as to performance.  Had I a bit more time I would redo that circuit without the roach.  Because it seems to me that the amps I’ve worked on recently that had vibrato/tremolo (ie. VoxAC100, Multivox 45) all had stronger. nicer sounding circuits.  Oh Well!

So, after this weekend, one of the things I’m going to have to get dialed in is doing videos.  Oh Great, you mean I have to figure out a new time-wasting activity?  Anyway, I’ve put it off for long enough and can’t ignore it anymore.  Lights, Camera, Action!!  . . . . . cut, cut, you’re doing it all wrong.

Try it again and this time with feeeeeeling.

I probably should have made two vents on the back panel, but considering the old one had none, it's all right.

With a sound so tough, you need a crome knob to handle it!

Full Frontal

~ by mmandjk on July 3, 2011.