6v6 Plexi Build Complete - What am I missing?

[martinman]

I don't like the tone. 

I have it built correctly, bias is dialed in, it's quiet, controls do what they're suppose to.  It's running into a 1x12 pine cabinet w/ Celestion Greenback.  I've tried guitars:  P90 equipped, Fender Esquire, and a Strat.  By far, the strat sounds the best -- it's my #1 -- so I expected a reprieve of my original thoughts.  Though, it's not enough to keep it around. 

...I mean, it could be that I just don't like Plexi's?  The fast attack, loud, in your face presence.  Perhaps I'm observing the difference between diode rectified and tube rectified?  There isn't any sag.  Although 6v6 platforms as well, the tweed 5f1 or Princeton DIY projects that I completed play nice with everything else and the tone is softer. 

I'm a bit perplexed -- I had a DIY GDS 18watt come through that I bought to essentially fix a DIY build gone wrong.  I ended up rehabbing it and kept it around for a while.  It too was way to loud and I eventually installed a power scaling mod MV.  In the end, I ended up selling it because it wasn't too versatile (IMO) - plus, I was going through a reverb phase..   

I'd say I'm in intermediate builder, but the differences between the 6v6 platforms that I own are stunning to say the least.  I'm sure the 6v6 plexi is a fine amp when you turn it up and get it cooking - something that just can't do too much of these days. 

Any thoughts or guidance?

[sluckey]

I don't like the tone. 

...I mean, it could be that I just don't like Plexi's?

Probably so. Are you sure the NFB phase is correct?

[martinman]

Hmm.  actually not sure about NFB phase - how do I check this w/o a scope? 

BTW, forgot to mention that all voltages at each point throughout the the amp are spot on.   

[acheld]

I mean, it could be that I just don't like Plexi's?  The fast attack, loud, in your face presence.  Perhaps I'm observing the difference between diode rectified and tube rectified?

That's the great thing about this hobby -- you get to try things out that you might not like in the end.

I am not a fan of Plexi's for the reasons you state.   It does exactly what it is supposed to do.

You can try switching the Blue and Brown wires from the OT to pin 3 of the 6V6's.   It's not a scope thing --  it's a hearing aid procedure. 

[labb]

You have to get the normal/bright volume mix right to your liking.

[bmccowan]

I agree with Labb on the mix thing. Other things that would change things in the direction you seek. Tube rectifier - cathode bias - 5751 in V1 position. You may or may not like any of those changes.

[dude]

Plus one on what labb and bmccowan mentioned. First off, try a tube rectifier 5AR4 or better yet a 5U4 if your PT can handle it. I find SS rectifier in a 6V6 Plexi is a little too sterile sounding unless wide open. The key is the mixing of the volumes, keep the normal channel at least halfway up if not more, then up the bright vol slowly, keep it less than the normal. Also, keep the presence down, around noon. You can play a bit with the NFB resistor too. Try a 12AY7 1st pre-amp tube if a 5751 doesn't help. Last, there is the pedal option up front, A Klon like pedal is great. 


BTW, l put a switch in my 6v6 Plexi for fixed or cathode bias, the cathode bias definitely changes the tone, more toward your liking. Not much involved, l think Sluckey has a layout with the changes on his site.

[martinman]

Just wanted to update the thread incase it's useful for the future.  I ended up installing the LarMar MV discussed in this thread:  https://el34world.com/Forum/index.php?topic=27348.0

I used the 2nd speaker output for the pot and ran the wires underneath the board.  I didn't have any shielded 2wire on hand, so I used what I had and twisted the wires together.  What a difference - great tone at a useable volume!  The ability to dial in tonality via the front panel and then have the extra 'attenuation' at the back is perfect. 

It's a keeper for now! 

Just curious though -- if I move the LarMar MV to the front and eliminate the current MV in the schematic, i'd assume it's just the same as running stock MV wide open?