6v6 plexi-ish build questions

[matt h]

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[Colossal]

The TMB channel, as currently built, mimics the "dark" channel of a plexi-type circuit (.02 coupler, 820/1uF-- yes I realize 25uF would be darker, but bear with me). If this were my only "plexi" channel, I'd go to a 2.7k/1uF setup on the cathode, and run a .0022uF coupling cap. Otherwise, as drawn, it's sorta run like a really dull "Rocket" style preamp.

EDIT: the .0022 cap replaces the current .0047? Just to make sure

Hi Don,

No, 0.0022uF replaces the 0.022uF coupling cap on the TMB channel. This goes along with changing the cathode to 2k7 on V1b. This would be my recommendation as well.

[donzoid]

Thanks Dave, I am going to try that tonight. Just got through sawing / splitting wood until dark...gonna take a break then get back to this.

[JazzGuitarGimp]

Thanks Dave, I am going to try that tonight. Just got through sawing / splitting wood until dark...gonna take a break then get back to this.

Do you use a hydrolic splitter, ir do you swing a splitting maul?

[donzoid]

Sorry to admit, I use the 'ol Maul, and a wedge/sledge if needed. Until I hit 50, it was all in the name of good productive activity. Now, several years after that magic number, I am seriously tempted to either buy a splitter, or have a buddy of mine who is a super-duper welder, fab one for me.

This year I have a half cord of BONZAI Maple. You know, those little tiny Japanese miniatures? Well someone I know had one that was like 45 years old, and had died. It was a good 16 feet in diameter, and 22 or so feet tall. That shit is the hardest wood I have EVER tried to split-more so than walnut. I finally got out my saws, and started cutting the quarters and even that was hard. Sure does burn for a long time tho.

[JazzGuitarGimp]

Holy moly! Bonzai on steroids!

[donzoid]

Ohhhh kayyyy.

Well, there comes a point where one just has to say enough is enough I guess with certain builds. Last night until quite very late /early? I tried a multitude of variations:
TMB coupler to .0022, cathode R to 2.7K/1uF, then 0.68uF cap.

100k plate R to 250K (had some 1% metal films in that "thought" it might reduce more noise), back to 100k, back to 250k again...current config is 250K plate, 2.7K cathode and 0.68uF bypass.

Normal channel - tried changing .01 coupler to .002, and played with the same basic back n forth on the 100K to 250K plate R, with an 820 and a 2.7K cathode R with the 47uF, a 22uF, a 10uF, 57uF, the 1uF...last config in there now is the .01 coupler, 100K, 2.7K / 1uF

End result- this amp just plain sounds like dog meat. Or, I have become hyper-critical and no longer an objective judge. Or, I need to lower my expectations. NAH!

I can't keep thrashing around with this thing its taken more of my time (and all of yours I dare say) than building both my Express AND my half power Rocket. I'm gonna hand off the chassis as-is to a friend and ask him to thrash on it for a week or so (play through it) and tell me what "he thinks". If his opinion is similar to mine, I'll throw it into the boneyard until the unresolved gnawing of a challenge not met eats at me until like a dog "returns to its own vomit", I'll go back to gut it and try something else.

Apologies...I just had to vent that to some folks who "had to have" been here before. A gallon of gas and a match come to mind. Aw c'mon, I hear at least SOME of you chuckling...and I will now return to reading my newly acquired book "designing tube preamps for guitar and bass" by, uhh, a well known UK Wizard.

[matt h]

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