fizzy mcfizzterton

[72fetter]

alright got the express to band practice and at full volume it is fizzy and midrange heavy when turned up to the appropriate volume.

the only change i have made to the schematic is the addition og the larmar master volume i bought from metro amp.

any ideas? my runs are all clean and i have already checked my layout to be correct.

[72fetter]

also...when i tuen down the guitar volume it is fizzy...it never cleans up...kinda like a fuzz pedal on low battery

[Ron Worley]

The express does NOT take to MVs or effects loops well at all. I suggest Dana Hall's VVR (www.hall amplification.com) as a better choice...

[72fetter]

also...when i tuen down the guitar volume it is fizzy...it never cleans up...kinda like a fuzz pedal on low battery

[72fetter]

ima shoot someone if thats the case...everybody said go get the larmar

[72fetter]

ok so if that is the case...what makes the express so finicky when it comes to master volumes? and how do we fix that.......not tryin to make the same amp ken did ya know.....its 2009 lol

[M Fowler]

The master volume does not work well in the Express.

You need to either start with preamp tube changes or adjust the circuit itself for less gain with different cathode resistor/bypass capacitor for frequency and gain.

Instead of 100k plate and 2.7k cathode gain of 47, try 100k plate and 1.8k for gain of 40.

Just a few ideas.

[geetarpicker]

Get an attenuator. Using a master volume takes the output stage distortion and the power supply sag out of the equation. At that point it's just a 3 stage preamp distortion type amp that won't clean up well, good for wankin' metal licks down at Banjo Center on 10 but not much else IMHO. A master in these is like driving a Ferrari but never going past 2000 rpm. You aren't even getting near the sweet spot. That aside, the midrange heavy nature may be your choice of speakers and/or OT transformer. Still these amps are strong in the mids however should not be nasal sounding. Yep these are finicky amps to get right, but worth the effort. I hope that helps. GK