The amp is built, and it works!  Powered by a 17vac salvaged transformer, through a diy full-bridge rectifier, into a cheapo buck convertor set at 16vdc, and housed in a salvaged VCR.  Played it through a 1×12 Celestion Gold.  It's gritty, but sounds pretty great for blues and rock.  It's also very quiet at idle.  It was a fun build!  Took some extra time due to moving components off-board.

I haven't finished my amp yet, but the option of having a gain boost sounds fun.  I discovered that the gain can be adjusted by adding a resistor in series with the 10uF capacitor.  In this case, a 1.2K resistor in series, will result is approximately 50x gain (as opposed to the 200x with no resistor).  I am confused however about what to do with pin 7?  In this schematic, it shows that pin 7 has a capacitor labelled as "bypass", and the lines are broken.  Can anyone please shed light on this?  I think I will do this mod, and make it switchable to have the option of a gain-boost.You cannot view this attachment.

I have a question regarding grounding of my setup.  As some of you know, I scavenged a stepdown transformer from an old Dell powered computer speaker (120 to 17), and added a full-bridge rectifier to change that to DC.  Finally, that will be regulated down to 16vdc using a buck converter.  This will then feed the amp (once I assemble it), and feed an external speaker.  The current transformer does not have a grounding plug, a fuse, or a power switch. The enclosure that I am using is plastic.  I am planning to add a power switch and an inline fuse, but am unsure about a ground.  I know from working with tube amps, that the voltages in there are lethal, and therefore grounding protects people from high voltages.  In the case of this amp, after the first stage of the transformer, the voltages are around 17VAC.  Is grounding necessary here?  Is the lack of a metal enclosure going to introduce a bunch of noise?  Will the lack of an earth-ground make this amp noisy?

Hi all, I got my kit last week, and was looking at options for powering the amp, and discovered I have a power transformer from an old Dell powered-speaker set.  It outputs 17v AC and 2.5A.  I have a full-bridge DIY rectifier kit on its way to convert it to DC.  I am not sure what the final DC voltage will be, but I am hoping for 16 VDC.  I cut open some shrink wrap on the power supply, and found a 0.1uf 275VAC capacitor in there.  Any ideas what this is for?  It appears to be wired in parallel?  Any thoughts on my proposed power supply?  I figure it's free, and it's great for learning more.

Hey all, I am looking to add a speaker jack to a fraken-amp that I assembled, but not in the traditional configuration.  I am looking to use the combo-amp as an external speaker cabinet, as opposed to having the amp switching to an external speaker cabinet.  I am looking at a Switchcraft 13A (transfer circuit) jack to achieve this.  Is this the right part for the job?  Will sharing the ground from the external amp, the internal amp, and the speakers work?  Do I need something to completely switch circuits (hot and ground)?  I have seen other setups that use two standard jacks, and then use a jumper cable to mitigate, but I prefer to have one input jack to keep things clean and simple.

Thanks