Top Hat Club -is it any more than a lightning with 6V6's ?

[Gee]

I then had to double my PI resistor to 44k and all is well.

My understanding of modifying an EL84 LTP amp to run 6V6's, is that the PI tail resistor should be changed from the 47k EL84 value to about 22k to increase the voltage swing from the PI to compensate for the higher level of drive needed by the 6V6.

It's interesting that the TopHat and Trainwreck schematics I have seen all keep the 47k value for EL84's and 6V6's.

[M Fowler]

You could use a trimmer to set that tail resistor.

[chopstuck]

I'm not adverse to trying the tail resistor change. The amp is plenty gainey though but not excessively so. I'm still going to try a parallel / single triode switch. It worked so well on a Spit I could have sold that amp a dozen times.

[steeve_a]

I didn't care for the cut control as drawn with the .0047 cap and the 250k pot. I tried the .0022 cap as well but didn't like it either. Just got too dull past the halfway point. I then put a 47k resistor in series with the cut pot so the range is now 50k-300k and it makes the whole sweep more useful and keeps some high end when on full cut.

Great thread! As for Cut controls I believe that part of their function is to compensate for differences in speakers, cabinets, tubes and iron from one build to the next without having to drastically revise the preamp or PI circuitry. So for any particular build I would not expect the Cut control to be useful throughout the full sweep of the pot- I often put it on the back or bottom of the chassis of a combo amp and just adjust it once (unless I replace the speaker or some of the tubes).

But sometime I do fine-tune the Cut control similar to what you did so that it is more functional as a front panel control. I did want to point out that what specifically worked for your build might not work as well in another build in case someone decides to copy exactly what you did. I believe it would be better for them to copy the procedure you followed: determine what range of the control gives you the most useful settings and revise the circuit appropriately. (If the amp is a head and not a combo you might want to keep the range a bit wider to compensate for different cabs.)

Sorry for pontificating*** on the first Monday of the New Year...

I really appreciate this thread- I think that I need a Club Royale in my life! And the discussion here is much more enlightening than just looking at a schematic.

Steve Ahola

*** Pontificating [present participle of pon·tif·i·cate]

1. (in the Roman Catholic Church) Officiate as bishop, esp. at Mass.

2. Express one's opinions in a way considered annoyingly pompous and dogmatic.

[chopstuck]

Just to be clear I did build that chassis so it could be head mounted and it was a Club Deluxe type so it has 6V6 outputs.

The Cut control is nice to adjust the high end when tubes age, voltage fluctuates or mostly invisible gremlins change amp settings between takes.

And yes I pontificate and proselytize.

but more likely I obfuscate and generalize.

Others merely deprecate and roll eyes.

Ok I stop now.

[Hepcat]

The wiring is a work of art! I hope to be able to do that some day. I've made three amps and I would only show you the inside of the third one!

[zelenko]

Hello! Is there any final schematic to this amp? I would like to take it for my next project!
)