Hi,
I have built a few Rubys, Noisy Crickets etc. Next I want to make something a bit more powerful - perhaps around 10 ~20 watts. But I would use it strictly for amplifying an archtop guitar for solo jazz so I am looking for sparkling clean sounds without distortion. (I figure this is opposite to most people.) Can anyone recommend either an amp schematics or a good IC chip for this kind of purpose?

Craig

Hi,

I built a couple Noisy Crickets earlier this year and really love the sound of these little amps. I ended up giving them away to people and recently built another one for myself. I have done all of them on perfboard with small changes. I am not 100% happy with the latest one. It has some hum that I don't remember the others having. Also the LEDs don't work. I have checked the original schematic and thought that I did everything correctly. Could some of your more experienced people have a look at my layout and see if there is something obvious wrong with it? I made a diagram of the layout in Illustrator - sorry for it being a bit messy.

Thanks,

Craig

Hi,
I want to make a few low wattage guitar amps. Projects like the Little Gem Mk II and Ruby (http://www.runoffgroove.com/littlegem.html) use an FET in an input buffer. I built one Ruby with a J201 I ordered online which doesn't work - I think it is because I soldered the FET directly and didn't use a socket. (Live and learn.)
They suggest one of:
    MPF102
    J201
    2N5457

The thing is, I have found that I live really close to a large number of electronics parts stores (in Osaka, Japan) so it is easier and cheaper to buy parts locally rather than order from SmallBear et. al. I just asked about buying such an FET at 3 different stores. At one they had tons of FETS, but said they didn't sell any of those three. At another store a helpful guy told me they don't sell those, but suggested one of three others that are the same. They are:
    K170
    K246
    K30

I bought one of each to try out. I am wondering (1) if these ARE substitutes and (2) how one knows what can be substituted. Doing a web search has so far not given me much information. It seems like there are other choices for FETs around here, but I have no idea how they are different.

Also, can anyone explain simply what an "input buffer" is/ does? and what purpose an FET serves here? I have read the wikipedia entry on FETs but don't really get it.

Thanks.

Hi,
I am interested in building the Little Gem (http://www.runoffgroove.com/littlegem.html) amp. It has been about 2 decades since I have picked up a soldering iron and I am afraid that things that may be obvious to others are not to me. I am wondering what value of capacitors are supposed to be used with the little gem. On the schematic it specify the value. It has just "100", "220", "0.047", "0.01". I am sure this is obvious to everyone else, but is this supposed to be uF, pF, nF or what?

Thanks in advance