Musical Fidelity Tube Amplifier & Preamp Board - 6J1 Vacuum Tube, Headphone Amp Kit

Excelente

The only instructions you have on this is following the silkscreen on the board. No instructions or schematics. I can't really tell that the volume going in is much different than out even with the volume wide open and a headphone signal with the volume maxed. This might work well to insert line level to add the tube effect but a headphone amp it ain't. The channels are a little off balance but without a schematic or anything I am not sure how to troubleshoot.

First off the plastic case is sold separately which was a slight bummer. I did end up buying one. I tried running it initially off DC 12v which is what most power adapters are. Was quiet and distorted. Figured out I needed 12v AC and got the correct adapter and it worked. The 2 best cheap mods I have found: Either replacing R14 and R19 with 100ohm resistors or just soldering a 220 ohm resistor on the underside of those supplied two resistors. This slightly opens up the sound stage and raises the volume some. Replacing C10 and C12 with 10uf caps or just bridging the originals with 10uf caps does really help the bass response like another review said. Also getting a matched pair of GE tubes helps improve the sound over the cheap ones supplied. This will cost you about as much as the kit though. With a nice set of headphones this little preamp does sound quite good. That resistor mod to R14/R19 really helped give the volume I wanted on my headphones. They are 40ohm speakers and I doubt you would get near the needed volume on any headphones of much higher resistance.

Outstanding! My love for kit building started in 1963, when I was young and out to prove that a woman could do anything. Not being overly domestic, I quickly developed a love for soldering. I've soldered on stained glass...built an Heathkit stereo FM receiver, a small FM radio, and now this pre-amp. It took a day to build this pre-amp, and the end result is awesome. Coupled with an inexpensive amp I bought from Amazon and a couple of small speakers, the sound is amazing!!! Although there were no instructions, the pcb was well marked so no written instructions were needed. If you're looking for a fun project, I highly recommend buying this kit. You won't be disappointed.

Did great job will jam for years thanks guys

Fun little kit to build, really crappy as an amplifier. Lacks all bass frequencies. Was louder and better quality to just plug the headphones in directly. Also comes with no instructions. Board is well labeled though

Not the easiest build due to no instructions or schematic but sounds great for the price.

Built it with included parts and wasn't impressed at all, then went back and did like what others said, it did improve it slightly. There's a slight hum just might be from old cheap RCA cables, i also replaced the annoying blue LED's with a yellowish orange i had on hand.

Came with all components, glass tubes intact, works great. Was hard to find a cheap 12VAC power supply but I found a 750mA one for five bucks and it works fine. The flashing RGB LEDs make cool interference sounds. I am using this for guitar, intentionally trying to get distortion, so I don't care about audio quality. It sounds and works great for that though! Doesn't fit the other clear plastic case I found, some minor drilling fixed that though.

This kit comes without any instructions, the parts are not labeled and there is no power supply provided and may neede to be AC instead of DC.

Lot of fun i will buy more !

kit was missing a part but I had a lot of projects on the shelf. By the time I checked it, it was too late to ask about it. Scavenged a pot from something else and it works as expected. Parts are reasonably in-spec and it's a fun kit to assemble. 4-stars cause I could have been in touch sooner and probably gotten the part but eh. As I recall it shipped sooner than expected as well.

So this is a fun little project to do some soldering and mess around with analog electronics but assembly is required and not all parts are included. There are no instructions but the silk screen is very detailed and it's pretty easy to put together. You'll want to buy a 12 volt alternating current (12 V AC / 1Amp ) power supply to feed this puppy. You'll also need some RCA cables for input signal and output signal depending on what you're using it for. You'll want to swap R14 / R19 out to match the impedance of your headphones if you find the volume too weak. If you google "Fever 6j1 circuit" you should be able to find the diagram easily. My biggest compliant is that the kit does not come with the pictured case which would be nice since there is about 56 volts of potential between the two rails.