drz400, the one I "borrowed" to do this build had that sound you memntioned. I liked the Gradual side better. My Clone doesn't seem to have that as bad. I just got a chance to crank it and man!!! I forgot how loud they are!!! Great feedback and harmonic content!
I used a high end impedance selector and custom tranny set and that might have something to do with it.
I will say "hat's off to Hogy and Mike" everytime I see one of their beautiful builds, I want to make one for myself and see if I can duplicate it.
you did a wonderfull Job!!! very professional.
Just a question (I have an express clone)... what differences can you feel between an express and a komet clone? (except power)
- playability and feel
- sound
what do you think I'll obtain if I change the pre section of my express according to komet values? (but keep the voltages of the express)
stefano
Well, it looks like I can figure it out from the thread at ampage. If there is some glaring omission, please let us know. I love my express-- it has a real sweetness to it's scream. But, I wouldn't mind seeing if there were a way to get a little more bottom end without the mud.
So is the following correct regarding the differences in the preamp:
Basically an Express preamp except the extra, unused triode is wired as a 'standard' cathode-follower and the third stage is now direct-coupled to the cathode follower. Output of the CF goes through a .022uF coupling cap and a 220K series resistor to the PI input cap. The third triode's cathode resistor is now 3.3K/unbypassed and there is a 220K/330K divider (220K series and 330K to ground) on the input of the third triode (selectable as 'gradual' or 'fast').
Fischerman wrote:there is a 220K/330K divider (220K series and 330K to ground) on the input of the third triode (selectable as 'gradual' or 'fast').
No. The K60 has the 220K/330K divider; the Concorde has no 'upper' resistor, only the 330K grid reference.
In both cases, the 'fast/gradual' is a split on the plate of the second triode, instead of a 100K plate load resistor there is a series string (82K and 22K), and the switch selects between the two.
Oddly, the switch is handling DC...I don't know why they didn't isolate the DC with two caps to the switch (it ain't like cost was an object).
In my build I replaced the 220K/330K divider with a 500K pot and did away with the fast/gradual switch.
Allynmey wrote:drz400, the one I "borrowed" to do this build had that sound you memntioned.
I've noticed this as well. Removing the 220K between the third triode and PI reduces it; also small (I used 47pF) snubbers across the second and/or third plate load resistors help too.
I tried adding cathode followers, a la Super Twin Reverb to mine. It did eliminate the noise but also changed the feel of the amp, and reduced overall volume.
Great feedback and harmonic content! 
