Hello, I'm from Norway!
So after a lot of experimentation and googling, I finally got this stuff working. I've basically just tried a lot of different circuits after one another and come to a pretty strange, but surprisingly decent sounding assembly. I'm using an MPF102 single transistor preamp into a basic baxandall tone control using BC109.
Because the power amp has very low input impedance and i don't know how to deal with that, I'm using the following circuit as a kind of secondary preamp with a small 9V 150ma power transformer reversed at the output, so the voltage doesn't affect the power amp. This also cancels all hum from the guitar pickups as well as unwanted radio frequencies.
However, I'm getting a tiny bit of background noise due to bad impedance matching, my guess.
Instead of the AC128/176 transistors, I'm using the complementary BC303 and BC301-5, because with the germaniums it sounds like a fuzz.
My question is: Could anyone suggest resistor values for proper biasing of this circuit using the BC transistors?
And also, is there some way, considering my current assembly, that I can get rid of some of the background noise?
Heres a datasheet: BC103
Thank you for your time reading and replying!
Very best
Tommi
So after a lot of experimentation and googling, I finally got this stuff working. I've basically just tried a lot of different circuits after one another and come to a pretty strange, but surprisingly decent sounding assembly. I'm using an MPF102 single transistor preamp into a basic baxandall tone control using BC109.
Because the power amp has very low input impedance and i don't know how to deal with that, I'm using the following circuit as a kind of secondary preamp with a small 9V 150ma power transformer reversed at the output, so the voltage doesn't affect the power amp. This also cancels all hum from the guitar pickups as well as unwanted radio frequencies.
However, I'm getting a tiny bit of background noise due to bad impedance matching, my guess.
Instead of the AC128/176 transistors, I'm using the complementary BC303 and BC301-5, because with the germaniums it sounds like a fuzz.
My question is: Could anyone suggest resistor values for proper biasing of this circuit using the BC transistors?
And also, is there some way, considering my current assembly, that I can get rid of some of the background noise?
Heres a datasheet: BC103
Thank you for your time reading and replying!
Very best
Tommi
Last edited:
it looks like this is no answer for you:
you will never get 100W from this with 9V power supply.
please look at attached graph, probably it is your fuzzlike distortion.
my circuit contain modern models for Si transistors, you can play with asc file in ltspice,
cheers
you will never get 100W from this with 9V power supply.
please look at attached graph, probably it is your fuzzlike distortion.
my circuit contain modern models for Si transistors, you can play with asc file in ltspice,
cheers
Attachments
I mean, the circuit posted is not the main power amp. I use it as a preamp as written in the thread. The 9V power transformer I mentioned is used as some kind of OT, only in reverse at the output signal to block DC. It works very well.
Then for the main power amp I use the Velleman K8060 which is a 100W module thing regularly used for active speakers.
I aslo made a diagonally ported cab for this with two 10" 100W celestion bass speakers, and it's pretty loud.
Then for the main power amp I use the Velleman K8060 which is a 100W module thing regularly used for active speakers.
I aslo made a diagonally ported cab for this with two 10" 100W celestion bass speakers, and it's pretty loud.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.