Guys with knowledge of circuit design, give me a hand.

[ej]

Originally Posted by spentron

First of all this thread is cool, because of subject. But this has got problems. Also you're overdriving it hugely with that input level.

The lack of a coupling cap distorts out D1 and D2 from Q4's bias.
The bias on both stages is probably almost cutoff. Look at the collector voltages.
If R25 is 100K etc. then in needs to be after the network. This would also eliminate C14, except reuse it on the first item.

So I actually think I fixed some of the issues you pointed out when I was playing with it more on saturday.



What do you think? I'm really eager to learn more about this stuff, all I have is basic working knowledge of electronics so if you wouldn't mind explaining in more detail I would appreciate it.

[spentron]

That helps some but you still have a loading issue with the low-fi filter. Without running any sims or anything it is clear the impedance/resistance scale (3K load) of the filter is too low for your amplifiers (47K or 15K source). It might be better to add a buffer for the second stage that can drive that thing, another possibility is rescaling the filter and then using a buffer or higher-impedance amp to avoid loss at its output. Or drop the filter awhile.

You're doing pretty good and there are limits to how much I can(will) help ... you need to look at the signals at many points in the circuit if you're not doing so already, not just the output. And eventually build one and see how it sounds.