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I'm in search of a good preamp circuit for my power amp (maybe amps, depends how this first one goes!). I've built a small 25W stereo power amp that runs on a single +12V DC supply. So, that pretty much eliminates any bipolar designs for the preamp (this time). I built a Professor Tweed pedal (from runoffgroove.com) for a friend and tried it in front of my power amp but found it MUCH too quiet. At anything less than say 70% the volume was way too low. Even at 100% the power amp was not pushing any decent output. I have verified the power amp is good with a mp3 player and hi-fi speakers so I know that's not the issue.
so, I'm at a loss now...
1) is it reasonable to contstuct a preamp running off +12V DC with sufficient gain to "properly" drive my power amp? I would like the most clean headroom possible as clipping tripath chips is generally not advised. Of course, all volume and tone controls will be passive.
2) How about using a LM386 chip as the preamp stage? I've read some posts on other boards indicating success with a ruby circuit as a preamp. I'm concerned that the low output impedance of the 386 won't be a good match for the power amp though.
here is the datasheet for the power amp chip I'm using. http://www.datasheetcatalog.org/data...h/mXyzxwww.pdf my input and feedback resistors are 22K (shown as 20K in the datasheet)
I would really appreciate any suggestions or advice you guys could give as I'm a bit in the dark here and don't want to waste a lot of time and money building circuits that won't work for my purposes.
FYI, I do have almost all the parts to build this (waiting on some caps): http://www.beavisaudio.com/Projects/...alveCaster.gif which I will try at 12V, but I don't have high hopes, so I'm looking for back-up plans.
-Matt
so, I'm at a loss now...
1) is it reasonable to contstuct a preamp running off +12V DC with sufficient gain to "properly" drive my power amp? I would like the most clean headroom possible as clipping tripath chips is generally not advised. Of course, all volume and tone controls will be passive.
2) How about using a LM386 chip as the preamp stage? I've read some posts on other boards indicating success with a ruby circuit as a preamp. I'm concerned that the low output impedance of the 386 won't be a good match for the power amp though.
here is the datasheet for the power amp chip I'm using. http://www.datasheetcatalog.org/data...h/mXyzxwww.pdf my input and feedback resistors are 22K (shown as 20K in the datasheet)
I would really appreciate any suggestions or advice you guys could give as I'm a bit in the dark here and don't want to waste a lot of time and money building circuits that won't work for my purposes.
FYI, I do have almost all the parts to build this (waiting on some caps): http://www.beavisaudio.com/Projects/...alveCaster.gif which I will try at 12V, but I don't have high hopes, so I'm looking for back-up plans.
-Matt