Posted by Manny Lopez on January 5, 2014 at 3:13am
I recently completed a Ruby amplifier using the schematic at this site:
http://www.runoffgroove.com/ruby.html
For the amount invested, this is a fun little amp! Since I have it built on breadboard, I was able to evaluate the Bassman mod to the circuit. I really enjoy this mod, but unfortunately when I strum really hard, there is a nasty break up that quickly goes way. It does not fade, but just intermittently distorts and then cuts out a half second or later while the note continues to ring. Is there something that is up or is that the nature of the circuit? Is it because it's bread boarded? Other speakers produce the same effect. This issue does not seem to be present in the stock configuration. My guitar has a humbucker, and my bass has two single or dual coils (I'm not sure) but the speaker is a small 2w 4" speaker from the surplus and I am running 12v instead of 9v and for the chip am using LM386-N4.
Any help is appreciated, as the bassman I heard on youtube did not seem to suffer from this problem of a nasty distortion, it was smooth drive.
https://www.youtube.com/watch?v=PYzV84OiA54&sns=em
I am really getting hooked on making these instruments and have a 3 string in the works, just waiting to trim the fretboard and mount it :D
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I have built several similar amps - the "Noisy Cricket". Mine do not like 12v either - do very well at 9v. Also use a tone pot w/.1uf cap. Since I usually have the tone down max, you could sub the cap the Bassman has on the volume pot for a .1uf and see it it tames the distortion. I also notice a better sound ( to my tin ears) by palm muting the bass string and trailing a finger behind the slide.
Thanks for all the help thus far. I have soldered it and it is running now. Sounds good, and nice to know connections are good. I am curious about the 220pf cap on the Bassman circuit. Do you add the cap and leave all other connections to the pot in place?
"Bassman -
Replace the .047uF cap from the FET source pin to the volume pot with a 0.1uF. Place a 220pF cap from lug 3 to lug 2 on the volume pot. Remove the Gain pot and place 2k2 fixed resistor between pins 1 and 8. In this configuration, Ruby sounds very much like an old Fender Bassman to our ears. With the Volume control at half rotation and below, you'll notice smooth and sparkly cleans with good depth. With the Volume pot set high, you'll hear nice overdrive that is great for blues playing. The transition from dirty to clean can be controlled with your picking or strumming. This aspect can add an extra dimension to your playing."
Yes, I believe that is what is intended for that capacitor...connecting between lug 2 & 3 of vol pot. Must alter the signal before continuing toward the LM386. I have a Ruby I made recently, without the Bassman change. Gives a nice clean when needed, and plenty of crunch too. The variable gain creates many different reactions in the amp.
Manny Lopez > Scott aka Farmer TedJanuary 6, 2014 at 9:50pm
My next step is to figure out if I can wire an extra 1/4" jack as a speaker out that will bypass the inner speaker when I plug a speaker cable in. Playing through a 15" cabinet is too loud in the apartment.
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
Thanks Tim. I found the reason for this in another electronics forum. Turns out it was the LM386N4, it doesn't like the higher voltage so much. I got an LM386N3 and the problem was solved. In the stock circuit, the N4 was fine, but the Bassman mod did not like it no matter what guitar I used. The Bassman mod sounds great though and naturally, works well for bass too ;)
Replies
I have built several similar amps - the "Noisy Cricket". Mine do not like 12v either - do very well at 9v. Also use a tone pot w/.1uf cap. Since I usually have the tone down max, you could sub the cap the Bassman has on the volume pot for a .1uf and see it it tames the distortion. I also notice a better sound ( to my tin ears) by palm muting the bass string and trailing a finger behind the slide.
Have fun and leterrip!
"Bassman -
Replace the .047uF cap from the FET source pin to the volume pot with a 0.1uF. Place a 220pF cap from lug 3 to lug 2 on the volume pot. Remove the Gain pot and place 2k2 fixed resistor between pins 1 and 8. In this configuration, Ruby sounds very much like an old Fender Bassman to our ears. With the Volume control at half rotation and below, you'll notice smooth and sparkly cleans with good depth. With the Volume pot set high, you'll hear nice overdrive that is great for blues playing. The transition from dirty to clean can be controlled with your picking or strumming. This aspect can add an extra dimension to your playing."
Yes, I believe that is what is intended for that capacitor...connecting between lug 2 & 3 of vol pot. Must alter the signal before continuing toward the LM386. I have a Ruby I made recently, without the Bassman change. Gives a nice clean when needed, and plenty of crunch too. The variable gain creates many different reactions in the amp.
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
Easy to do, just intercept signal after C5, the 220uF cap, with a three prong, on/on switch. C5 to middle prong, amp speaker to one of other prongs, and remaining prong to jack out...
The guitar pots and tone caps may have something to do with how it sounds ... I would try different guitars to see if anything changes.
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