Hi! I have started working on my tube amp (Bugera V5), and am having a lot of fun doing it, and in the process, am even learning about transistor amp circuits.
You see: my amp comes with a digital plate reverb (Belton Delay Module), which generally sounds pretty good. But it has a tail of high-end sizzle that becomes very noticeble if, like me, you replace the stock speaker of your amp with a new speaker that’s more responsive to high frequencies.
So, I decided to look a the amp schematic further (I have included the schem for you to peruse), and combined with that and doing research on the web for general transistor amp circuits, I figured out how to take the offending high frequencies out of the reverb: I installed a 10000pf cap in parallel to the 120k Collector resistor coming from B+. This has definitely brought the highs down, to a very warm and realistic sounding reverb level. But, as all you-who are much more experienced with common emitter circuits than I am-could have predicted, it also seems to have brought down the overall gain going through the transistor, and therefore the reverb has taken a hit in volume.
No problem, right? Just figure out now how to bring the overall volume of the transistor back up, right? That’s what my basic Audio Engineering experience tells me. I’ve done some research on Common Emitters, and based on what I have gleaned, I see that one of the most basic ways to increase the gain level of the circuit is to include a capacitor in parallel to the Emitter resistor. If you look at my schematic, you’ll see that there is already a cap there (electrolytic, 100uf, 25V).
I was wondering this:
Am I on the right track as far as a strategy goes (is modifying the Emitter Cap the best way to bring up the gain level of this circuit?
If so, what overall value of new cap do I need in order to bring the gain level back up to where it was before?
What is the overall method/formula one needs to employ in order to figure out such things?
Thanks for your time.