Revised schematic and possible mods now online: http://runoffgroove.com/ruby.html
I'll get less output from a J201 even if I lower the source resistor to 3.9? How about 1k with a bypass cap?
RDV
Looks great! Would you recommend the Ruby over the Little Gem? I'll probably make one of these in the near future - maybe both in the same cab with independant 3" speakers.
Quote from: RDVI'll get less output from a J201 even if I lower the source resistor to 3.9? How about 1k with a bypass cap?RDV
Even when using a 3k9 source resistor, the J201 has lower output than the MPF102. A J201 can still used with pleasing results - the volume difference is noticeable, but not enough for us to advise against using one.
Since the FET is being used as a buffer, using a 1k resistor and bypass cap at the source will not work. If that was done, you'd also need to move the output cap to the drain and add a bias trimmer to the drain as well. Then you have a FET gain stage, like the first stage of the Double D (http://runoffgroove.com/doubled.html).
Quote from: Craig VLooks great! Would you recommend the Ruby over the Little Gem? I'll probably make one of these in the near future - maybe both in the same cab with independant 3" speakers.
The Little Gem is still a worthwhile circuit, that's why we're not removing the schematic from the site. However, Ruby is the "new and improved" version and we feel that it will be more satisfying for the builder.
B, that Bassman mod sounds like it kicks mucho ass. I'm going to try it first thing tonight after work!
I think you've taken the Little Gem in the next step to becoming a full-featured and polished practice amp. A big round of applause is warranted for this latest effort. Good job!
Build report on the Bassman mods:
Excellent. It is even better.
I also wanted to mention that the lm386 is a piece of garbage compared to the JRC386. I was using the lm386 and could not get the amp to sound decent at all. With the gain all the way up, there was a secondary note, highly distored under the fundamental, and the sound was thin. With the JRC chip, the sound is smoother, thick, and ampy. Don't waster your time with the LM386!
Just finished the build. The Ruby is a nice - very pleasing sounding amp. Using the lm386 and J201 (since that is what I had in the parts bin) and find it to be loud enough (using headphones) Will have to see about some of the other mods suggested. Did use the 12 volt source -
This is a grat project - easy build.
Great work - and Thank you
BILLYL
I switched mine from the J201/10k buffer to the MPF102/3.9k buffer last night and I must say that if you like a cleaner sounding amp the lower gain J201/10k buffer will be more to your liking cause the MPF102/3.9k makes the amp start to break up much sooner IMNSHO.
Regards
RDV
i have a fewquestions about the little amp,
firstly is there an alternative to an LM386, because having heard that it sounds like rubbish, i would like a good sound, so i suppose i would need another I.C (EDIT i cannot get a JRC386, as they do not sell them in my local shop :( ). Secondly, as for the speakers, do they have to be a certain wattage, and can i wire two up, instead of one ( thats because im a power hungry freak and the more noise the better :twisted: )
thanks to any one that can help!
callum
ps. just found out that my local shop doesnt sell perfboard, only stripboard :(
Quote from: blabji have a fewquestions about the little amp,
firstly is there an alternative to an LM386, because having heard that it sounds like rubbish, i would like a good sound, so i suppose i would need another I.C (EDIT i cannot get a JRC386, as they do not sell them in my local shop :( ). Secondly, as for the speakers, do they have to be a certain wattage, and can i wire two up, instead of one ( thats because im a power hungry freak and the more noise the better :twisted: )
thanks to any one that can help!
callum
ps. just found out that my local shop doesnt sell perfboard, only stripboard :(
The LM386-1 will work fine if that's what you've got. It will run any guitar speaker you plug into it. I run my 412 with one often. It in fact sounds better to me through a big cab.
Regards
RDV
Thanks,
I am probably gonna have it set like a mini 2-12 head and cab
exact dimensions are:
HEAD- 15x5x10 CM
CAB- 20x15x10 CM
Also, I would be able to put a power switch in the amp wont I? I could just put it at the 9+ side of the the battery, and I would be able to use a L.E.D indicator if i used a DPDT toggle switch wouldn't I?
Last question ( I promise :oops: ) for a headphone socket, can I put it so that when i plug in, it will bypass the speakers, (not like there too loud, i just like headphones :wink: )
thanks for all the help guys
callum
please help soon, as i will have to go and get the parts in 30 mins, and i wont know exactly what to get
cheers
callum
ps. sorry if im being slightly demanding :)
You can use a power switch in the amp, and you can put a LED. About the jack, you need to take a look for jacks with switches. I don't know if you will find this kind of jack for heardphones, I think you will find only for cables (the common jacks in pedals). They have 3 lugs if the jack is mono or 5 lugs if the jack is stereo.
Use a socket for the chip and simply use an lm386 for now. But I promise, a JRC 386 sounds a huge amount better. I had an lm386-1, if you can get your hands on a higher rated version, it may sound better, I don't know.
You guys that have lm386's, it would be worth your while to get a JRC386.