6AU6 vs. EF86?

[DowdyLama]

I'll have to try an SRPP setup sometime.
FWIW: I had great results with the 6SL7 in (SRPP) audio application.

[markh]

According to Mr. Valve Wizard, the SRPP is good for guitar amps because the top and bottom are direct coupled, and therefore no ugly blocking distortion can occur. The cascode is also direct coupled, but is supposed to sound more "pentodey" (a new word I just invented ).

I plan to try both (Real Soon Now) to see how they sound in a guit-amp.

--m

[rjgtr]

Well I just couldn't stop my curiosity so I turned the normal channel of my 1974 clone into a Cascode from the SRPP. The Cascode is a lot richer sounding. There's a lot of Harmonics going on. It is also darker and actually not quite as loud as the stock Trem channel. From the coupling cap I am going into a stock Trem channel vol/tone.

The voltage on the 'top' plate ends up being something like 306V with a 100k resistor. I wonder if a 220k would be better? I'm also using a 1.5K on the 'bottom' cathode with a 25uf cathode cap. I'm seriously thinking I should change this to a .68uf or 1uf to reduce a little bass.

So far it is a real interesting sound. It might just be a good way to add richness to a drive channel. I tried a Tube screemer set for clean to goose it and that's nice, too.

So far I think the SRPP is a good choice if you want a solid clean tone and a bunch of volume. If you want growl, the cascode seems to do it well.

[DowdyLama]

I really like the cascode [6DJ8] sound, 'tho I have zero experience with a cascoded 12AX7.
Internal resistance of a cascoded 'AX7 is in excess of 7 Meg; so increasing the plate resistor might be a good thing to try.

[rjgtr]

Ok I made the plate resistor change and the cap change and I like the results. The channel growls a little more and is more mid focussed (in a good way).

[ny_racer_xxx]

You guys are giving me a..... Never mind...
I have a stereo amp my dad built back in 60's when i was born. I took it apart a 100 years ago and was going to rebuild it.. Never got around to it... I'm building a TMB because I want to gain some knowledge so I can rebuild that amp...
The amp uses 1x 12au7 on the input, 2x 6au6's to feed the output stage, and 2x 6v6gt's for the power section. I have all the iron, and all the original tubes, Western Union tubes... My dad worked for Western Union, wonder how he got them???
I have a ADA MP1 preamp, but always played it through a solid state power amp, never quite loved the tone, it really needs some tubes on the output...

CR