Circuit analysis

[Rod]

Hi everyone!

Well i'm trying to understand, what will be the results for each part of the attached sample circuit's.
The part 3 will remove some trebles, right?
The part 2 will lower the bass, when signal pass trough C3 and C4, right?
Part 1 , i dont have any idea of this will make to the signal, can anyone help here?





What will be the results of the signaled part of the sample circuit?
What frequencies will be affected? the bass and the treble?



How can i preview the signal frequencies?

[Enzo]

Part 1. Your first tube is a basic gain stage, the signal leaves it through C3. AFter C3, the signal path branches apperantly to go to two separate channels. Part 1 sends the signal off to some circuits off the right edge of the picture. R20 and R21 form a voltage divider - basically a volume control premanently set - and it substantially reduces the signal level for the following circuits. A 1000/22 divider. C21 is in parallel with the upper element of the divider, and it acts as a brightness cap. 100pf is fairly small, so it passes pretty high frequencies around R20. So the signal going off to the right will be much lower level and somewhat brighter than what came through C3.

Part 2. I suppose it will lop off some bottom end, but I don;t feel like calculating the freqs, someone else can do that. Basically we have C3 outputting from the first tube C4 couples it into part 3 and the second tube.

Part 3. You should include R7. R7 and R25 also form a voltage divider, but their vgalues are a lot closer together than the other channel feed. 100k/220k, so basically the signal from C3 is reduced by about a third in level. Yes, C8 will roll off some highs in that channel.


SOmeone else can calculate the Mesa tone shaping stack.

G over to Duncanamps and download the Tone Stack Calculator. It is a bit of free software that lets you play with a variety of tone control circuits and see the response curves change in real time. Very cool.