The Amp Garage

That's pretty wood. What is it?

I've had a Mk III since the last 80's. I don't play it much though. If I sell it, I won't get enough for it. So I guess I'll keep it until I die. Therefore, I have been heavily tweaking it. I have considered building a point to point version. Maybe I should build a Dumble in the chassis? Dumble/Boog...

The phenolic needed to accurately manufacture the perfboard needs to be 3/32" thick xxx grade phenolic. The companys that use to manufacture it actually "Punch" the holes instead of drilling them and anything over 3/32 won't work for their process. Trust me when I say I contacted every manufacturer...

Both kinds of perfboard used in Ken's amps is extinct. There has been people that have found some in old electronic shops that has had it sitting around on shelves for the past 15 years. I have checked into getting it made but the phenolic isn't available any more either. The push-in terminals Ken ...

strat57 wrote:Pic's and sounds of "Kathie"! Hmmm.... will these be "x" rated?

Not if I want to stay married

Hi all. After much investigation, my fisrt express (Kathie) is up and running. As it turns out, I had 2 matched pairs of EL34s - each one with a bad tube. I took the good tube from each pair and plugged them in. Voila! So, it turns out that I had it right the first time. Thank you rhinson for helpin...

that being the case it sounds like a defective tube----i've had this happen numerous times with new tubes out of the box and had to send back to the distributor for replacements. unfortunately these days, even with the culling and testing most places say they do, it seems to happen all too often. i...

i'm not saying you can't/shouldn't do it----but depending on a bunch of things you may not be able to get away with it simply by using the same values over a second time for your second pot/resistor combo. just look at your schematic-----you have 2 20k pots and 2 47k resistors in parallel to ground...

If it works for you then cool but...... Thanks. I will get TUT3 soon. Until then, I'll reserve comment. I do know that my 1987 was the most hum and buzz free with separate preamp and power busses (grounded at opposite ends of the chassis). My newly completed Express has 3 busses grounded at 3 point...

you can't have 2 bias tail resistors-(you only need one)---they're in parallel to ground and in effect lower your overall resistance to where you don't have enough neg. voltage to have an appropriate bias range---with the 2 56k's you really only have a single 28k resistance---not high enough. just ...

The sound is nice. It is clean to about 9:00 and starts breaking up after that. 12:00 to 1:00 provides plenty of headroom. My 1987 (DIY Marshall 50W) cleans up better with the guitar volume control, but the express has more gain. The harmonic feedback it awesome. The express is brighter than the 198...

and one more

and some more...

Here are more pictures. Note, I am having a cabinet made for me, so she will be naked for a while.

I got my first express running over the weekend. Her name is Kathie (my wife's name). She sounded pretty nice - clear and no hum or buzz. However, I may have a problem. I played her late Friday a bit and a bit the next morning. I turned her off , moved her across the room and hooked up my DMM to rec...