How much of this fixed tone stack can i remove?(killer ant circuit)

[jibberish]

i want to test the thing with no master gain and no tone stack.

here is the schematic to the ant:http://www.sewatt.com/files/sewatt/BLACKHEART%20BH1%20SCHEMATIC.pdf

they have the 4 triodes in a row(2 per 12ax7).  Between the 3rd and 4th(output stage) are a fixed tone stack, a fixed master gain voltage divider and a filter resistor going into the final stage.

ok, first the 2 fixed gain resistors go, then i put a pot in heh, but i want to feel this amp in an uncluttered state.
there are many implications that the uniform component values selected by blackheart were more economic compromises and there is much room for tweaking. i would like to play with that before i put the tone and gain pots in.

here is my question. the guy in the article says just lift the ground leg from that 4-resistor/3-cap network and you kill the tone stack.  i still see the signal going through an RC network.  rc=hi pass to me.  
****edit: DUH, the article, might help lolhttp://music-electronics-forum.com/t20518/
could i just remove all 7 components and go straight from triode3 to the input filter resistor of triode 4?(or to the gain pot, THEN the filter )??

also, does that filter resistor REALLy have to be that big?  noise on your preamp signal =huge noise on output since it gets amplified along with the signal
It seems the signal is voltage divided ok, so could i even eliminate that filter resistor for testing? looks safe (famous last words)

[jibberish]

this is an edit to the above post but the fcking text thing gets real stupid after so many lines

that input filter resistor on the input of triode 4 actually seems like it would attenuate the input divided with the input impedance of the triode itself ( i need to look that up, if the input impedance is megohms like an op amp input, nm..loss is negligible...)

[dunwichamps]

removing the ground is good enough for getting a bypass. IF you want to bypass it in a more indepth way you would need to have a coupling cap off the cathode follower cathode resistor (R8) to couple it to the divider b4 the last triode. Lot of work for not much gain.


filter resistor? b more specific. thats confusing to me

[dunwichamps]

The divider b4 the Class A power stage is there to prevent too much signal from hitting the tube, The 100k going into that tube is there to prevent blocking distortion and it will also filter off highs due to Miller Capacitance. Do not remove the 100k resistor, esp if you going to increase the signal hitting that tube

[jibberish]

ok, you nailed my niggling concern: some type of cap needs to stay in there to correctly couple the stages.

i will get down and dirty with that tube's specs here presently since i need to anyway.,it's been all about the output impedance so far, but i do need the whole picture.
and the last resistor on the input to triode 4 will stay.  maybe once i get a feel for the actual levels, i might have a chance to safely reduce its value a bit, but not a big priority
for sure at the end, i will also put the tone stack back in and add 3 pots.

and many thanks yet once again for your time.

[jibberish]

that is a bit confusung. stage2->stage3 goes from some divided but still large voltage straight into triode 3

yet that cathode tap on op #3 with no divider resistor above, needs to be coupled to IP #4.
stage 3 is weird..like a buffer or something. you can tell i still have some holes to fill in the big picture

Are these "coupling" caps there primarily to block the big dc?

[Hemisaurus]

Are these "coupling" caps there primarily to block the big dc?

yes.

[jibberish]

i KNOW i have some big holes to fill. sheezuss










( ha ha, j/k
i'm actually assuming that was the coupling cap question's answer. srsly thx   )

DOH! it wasnt?!?!?!?!?

[Hemisaurus]

[dunwichamps]

that is a bit confusung. stage2->stage3 goes from some divided but still large voltage straight into triode 3

yet that cathode tap on op #3 with no divider resistor above, needs to be coupled to IP #4.
stage 3 is weird..like a buffer or something. you can tell i still have some holes to fill in the big picture

Are these "coupling" caps there primarily to block the big dc?

stage 3 is a cathode follower, and this amp has used the traditional scheme of using a DC coupled cathode follower. You can couple stages with DC so long as you are not going to use a pot to control something between them, as this leads to scratching sounds in the pot when you flow some DC through it or you are not going to load down the DC power supply with a small resistor.

The cathode follower (stage 3) has ideally unity gain so there is not increase in game from Stage 2 to Stage 3, merely a change in impedance from the large plate impedance of Stage 3 (>40K) to the low impedance of Stage 3 (at the cathode something like <2k). This is a much better arrangement for driving the tone stack because it present a large load to the plate of a preamp tube and there is less insertion loss from the tone stack as compared to a plate driven stack.

[dunwichamps]

you need a grid leak on V2 and V4, cant run it without one. 1meg will suffice if u want max gain

[Hemisaurus]

I love it when you take things seriously

[dunwichamps]

I love it when you take things seriously

mad serious business up in here. Electrical Fuckin Engineering, Boom!

And fuck thats a lot of signal hitting the Class A power amp, it might sound like a dogshit with that much signal even with a large grid stop

[Hemisaurus]

What do you use for drawing schematics?

[dunwichamps]

What do you use for drawing schematics?

Express Schematic, free and simple I also use ExpressPCB